prctl: generalize PR_SET_MDWE support check to be per-arch

Patch series "ARM: prctl: Reject PR_SET_MDWE where not supported".

I noticed after a recent kernel update that my ARM926 system started
segfaulting on any execve() after calling prctl(PR_SET_MDWE). After some
investigation it appears that ARMv5 is incapable of providing the
appropriate protections for MDWE, since any readable memory is also
implicitly executable.

The prctl_set_mdwe() function already had some special-case logic added
disabling it on PARISC (commit 793838138c15, "prctl: Disable
prctl(PR_SET_MDWE) on parisc"); this patch series (1) generalizes that
check to use an arch_*() function, and (2) adds a corresponding override
for ARM to disable MDWE on pre-ARMv6 CPUs.

With the series applied, prctl(PR_SET_MDWE) is rejected on ARMv5 and
subsequent execve() calls (as well as mmap(PROT_READ|PROT_WRITE)) can
succeed instead of unconditionally failing; on ARMv6 the prctl works as it
did previously.

[0] https://lore.kernel.org/all/2023112456-linked-nape-bf19@gregkh/


This patch (of 2):

There exist systems other than PARISC where MDWE may not be feasible to
support; rather than cluttering up the generic code with additional
arch-specific logic let's add a generic function for checking MDWE support
and allow each arch to override it as needed.

Link: https://lkml.kernel.org/r/20240227013546.15769-4-zev@bewilderbeest.net
Link: https://lkml.kernel.org/r/20240227013546.15769-5-zev@bewilderbeest.net
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Acked-by: Helge Deller <deller@gmx.de> [parisc]
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Florent Revest <revest@chromium.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Russell King (Oracle) <linux@armlinux.org.uk>
Cc: Sam James <sam@gentoo.org>
Cc: Stefan Roesch <shr@devkernel.io>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Cc: <stable@vger.kernel.org> [6.3+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

getrusage: use sig->stats_lock rather than lock_task_sighand()

lock_task_sighand() can trigger a hard lockup. If NR_CPUS threads call
getrusage() at the same time and the process has NR_THREADS, spin_lock_irq
will spin with irqs disabled O(NR_CPUS * NR_THREADS) time.

Change getrusage() to use sig->stats_lock, it was specifically designed
for this type of use. This way it runs lockless in the likely case.

TODO:
- Change do_task_stat() to use sig->stats_lock too, then we can
remove spin_lock_irq(siglock) in wait_task_zombie().

- Turn sig->stats_lock into seqcount_rwlock_t, this way the
readers in the slow mode won't exclude each other. See
https://lore.kernel.org/all/20230913154907.GA26210@redhat.com/

- stats_lock has to disable irqs because ->siglock can be taken
in irq context, it would be very nice to change __exit_signal()
to avoid the siglock->stats_lock dependency.

Link: https://lkml.kernel.org/r/20240122155053.GA26214@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Dylan Hatch <dylanbhatch@google.com>
Tested-by: Dylan Hatch <dylanbhatch@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand()

Patch series "getrusage: use sig->stats_lock", v2.


This patch (of 2):

thread_group_cputime() does its own locking, we can safely shift
thread_group_cputime_adjusted() which does another for_each_thread loop
outside of ->siglock protected section.

This is also preparation for the next patch which changes getrusage() to
use stats_lock instead of siglock, thread_group_cputime() takes the same
lock. With the current implementation recursive read_seqbegin_or_lock()
is fine, thread_group_cputime() can't enter the slow mode if the caller
holds stats_lock, yet this looks more safe and better performance-wise.

Link: https://lkml.kernel.org/r/20240122155023.GA26169@redhat.com
Link: https://lkml.kernel.org/r/20240122155050.GA26205@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Dylan Hatch <dylanbhatch@google.com>
Tested-by: Dylan Hatch <dylanbhatch@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

prctl: Disable prctl(PR_SET_MDWE) on parisc

systemd-254 tries to use prctl(PR_SET_MDWE) for it's MemoryDenyWriteExecute
functionality, but fails on parisc which still needs executable stacks in
certain combinations of gcc/glibc/kernel.

Disable prctl(PR_SET_MDWE) by returning -EINVAL for now on parisc, until
userspace has catched up.

Signed-off-by: Helge Deller <deller@gmx.de>
Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Sam James <sam@gentoo.org>
Closes: https://github.com/systemd/systemd/issues/29775
Tested-by: Sam James <sam@gentoo.org>
Link: https://lore.kernel.org/all/875y2jro9a.fsf@gentoo.org/
Cc: <stable@vger.kernel.org> # v6.3+

mm: add a NO_INHERIT flag to the PR_SET_MDWE prctl

This extends the current PR_SET_MDWE prctl arg with a bit to indicate that
the process doesn't want MDWE protection to propagate to children.

To implement this no-inherit mode, the tag in current->mm->flags must be
absent from MMF_INIT_MASK. This means that the encoding for "MDWE but
without inherit" is different in the prctl than in the mm flags. This
leads to a bit of bit-mangling in the prctl implementation.

Link: https://lkml.kernel.org/r/20230828150858.393570-6-revest@chromium.org
Signed-off-by: Florent Revest <revest@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alexey Izbyshev <izbyshev@ispras.ru>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ayush Jain <ayush.jain3@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Cc: Topi Miettinen <toiwoton@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

getrusage: use __for_each_thread()

do/while_each_thread should be avoided when possible.

Plus this change allows to avoid lock_task_sighand(), we can use rcu
and/or sig->stats_lock instead.

Link: https://lkml.kernel.org/r/20230909172629.GA20454@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

getrusage: add the "signal_struct *sig" local variable

No functional changes, cleanup/preparation.

Link: https://lkml.kernel.org/r/20230909172554.GA20441@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

prctl: move PR_GET_AUXV out of PR_MCE_KILL

Somehow PR_GET_AUXV got added into PR_MCE_KILL's switch when the patch was
applied [1].

Thus move it out of the switch, to the place the patch added it.

In the recently released v6.4 kernel some user could, in principle, be
already using this feature by mapping the right page and passing the
PR_GET_AUXV constant as a pointer:

prctl(PR_MCE_KILL, PR_GET_AUXV, ...)

So this does change the behavior for users. We could keep the bug since
the other subcases in PR_MCE_KILL (PR_MCE_KILL_CLEAR and PR_MCE_KILL_SET)
do not overlap.

However, v6.4 may be recent enough (2 weeks old) that moving the lines
(rather than just adding a new case) does not break anybody? Moreover,
the documentation in man-pages was just committed today [2].

Link: https://lkml.kernel.org/r/20230708233344.361854-1-ojeda@kernel.org
Fixes: ddc65971bb67 ("prctl: add PR_GET_AUXV to copy auxv to userspace")
Link: https://lore.kernel.org/all/d81864a7f7f43bca6afa2a09fc2e850e4050ab42.1680611394.git.josh@joshtriplett.org/ [1]
Link: https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=8cf0c06bfd3c2b219b044d4151c96f0da50af9ad [2]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

riscv: Add prctl controls for userspace vector management

This patch add two riscv-specific prctls, to allow usespace control the
use of vector unit:

* PR_RISCV_V_SET_CONTROL: control the permission to use Vector at next,
or all following execve for a thread. Turning off a thread's Vector
live is not possible since libraries may have registered ifunc that
may execute Vector instructions.
* PR_RISCV_V_GET_CONTROL: get the same permission setting for the
current thread, and the setting for following execve(s).

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Vincent Chen <vincent.chen@sifive.com>
Link: https://lore.kernel.org/r/20230605110724.21391-22-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

mm/ksm: unmerge and clear VM_MERGEABLE when setting PR_SET_MEMORY_MERGE=0

Patch series "mm/ksm: improve PR_SET_MEMORY_MERGE=0 handling and cleanup
disabling KSM", v2.

(1) Make PR_SET_MEMORY_MERGE=0 unmerge pages like setting MADV_UNMERGEABLE
does, (2) add a selftest for it and (3) factor out disabling of KSM from
s390/gmap code.


This patch (of 3):

Let's unmerge any KSM pages when setting PR_SET_MEMORY_MERGE=0, and clear
the VM_MERGEABLE flag from all VMAs -- just like KSM would. Of course,
only do that if we previously set PR_SET_MEMORY_MERGE=1.

Link: https://lkml.kernel.org/r/20230422205420.30372-1-david@redhat.com
Link: https://lkml.kernel.org/r/20230422205420.30372-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Stefan Roesch <shr@devkernel.io>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add new api to enable ksm per process

Patch series "mm: process/cgroup ksm support", v9.

So far KSM can only be enabled by calling madvise for memory regions. To
be able to use KSM for more workloads, KSM needs to have the ability to be
enabled / disabled at the process / cgroup level.

Use case 1:
The madvise call is not available in the programming language. An
example for this are programs with forked workloads using a garbage
collected language without pointers. In such a language madvise cannot
be made available.

In addition the addresses of objects get moved around as they are
garbage collected. KSM sharing needs to be enabled "from the outside"
for these type of workloads.

Use case 2:
The same interpreter can also be used for workloads where KSM brings
no benefit or even has overhead. We'd like to be able to enable KSM on
a workload by workload basis.

Use case 3:
With the madvise call sharing opportunities are only enabled for the
current process: it is a workload-local decision. A considerable number
of sharing opportunities may exist across multiple workloads or jobs (if
they are part of the same security domain). Only a higler level entity
like a job scheduler or container can know for certain if its running
one or more instances of a job. That job scheduler however doesn't have
the necessary internal workload knowledge to make targeted madvise
calls.

Security concerns:

In previous discussions security concerns have been brought up. The
problem is that an individual workload does not have the knowledge about
what else is running on a machine. Therefore it has to be very
conservative in what memory areas can be shared or not. However, if the
system is dedicated to running multiple jobs within the same security
domain, its the job scheduler that has the knowledge that sharing can be
safely enabled and is even desirable.

Performance:

Experiments with using UKSM have shown a capacity increase of around 20%.

Here are the metrics from an instagram workload (taken from a machine
with 64GB main memory):

full_scans: 445
general_profit: 20158298048
max_page_sharing: 256
merge_across_nodes: 1
pages_shared: 129547
pages_sharing: 5119146
pages_to_scan: 4000
pages_unshared: 1760924
pages_volatile: 10761341
run: 1
sleep_millisecs: 20
stable_node_chains: 167
stable_node_chains_prune_millisecs: 2000
stable_node_dups: 2751
use_zero_pages: 0
zero_pages_sharing: 0

After the service is running for 30 minutes to an hour, 4 to 5 million
shared pages are common for this workload when using KSM.


Detailed changes:

1. New options for prctl system command
This patch series adds two new options to the prctl system call.
The first one allows to enable KSM at the process level and the second
one to query the setting.

The setting will be inherited by child processes.

With the above setting, KSM can be enabled for the seed process of a cgroup
and all processes in the cgroup will inherit the setting.

2. Changes to KSM processing
When KSM is enabled at the process level, the KSM code will iterate
over all the VMA's and enable KSM for the eligible VMA's.

When forking a process that has KSM enabled, the setting will be
inherited by the new child process.

3. Add general_profit metric
The general_profit metric of KSM is specified in the documentation,
but not calculated. This adds the general profit metric to
/sys/kernel/debug/mm/ksm.

4. Add more metrics to ksm_stat
This adds the process profit metric to /proc/<pid>/ksm_stat.

5. Add more tests to ksm_tests and ksm_functional_tests
This adds an option to specify the merge type to the ksm_tests.
This allows to test madvise and prctl KSM.

It also adds a two new tests to ksm_functional_tests: one to test
the new prctl options and the other one is a fork test to verify that
the KSM process setting is inherited by client processes.


This patch (of 3):

So far KSM can only be enabled by calling madvise for memory regions. To
be able to use KSM for more workloads, KSM needs to have the ability to be
enabled / disabled at the process / cgroup level.

1. New options for prctl system command

This patch series adds two new options to the prctl system call.
The first one allows to enable KSM at the process level and the second
one to query the setting.

The setting will be inherited by child processes.

With the above setting, KSM can be enabled for the seed process of a
cgroup and all processes in the cgroup will inherit the setting.

2. Changes to KSM processing

When KSM is enabled at the process level, the KSM code will iterate
over all the VMA's and enable KSM for the eligible VMA's.

When forking a process that has KSM enabled, the setting will be
inherited by the new child process.

1) Introduce new MMF_VM_MERGE_ANY flag

This introduces the new flag MMF_VM_MERGE_ANY flag. When this flag
is set, kernel samepage merging (ksm) gets enabled for all vma's of a
process.

2) Setting VM_MERGEABLE on VMA creation

When a VMA is created, if the MMF_VM_MERGE_ANY flag is set, the
VM_MERGEABLE flag will be set for this VMA.

3) support disabling of ksm for a process

This adds the ability to disable ksm for a process if ksm has been
enabled for the process with prctl.

4) add new prctl option to get and set ksm for a process

This adds two new options to the prctl system call
- enable ksm for all vmas of a process (if the vmas support it).
- query if ksm has been enabled for a process.

3. Disabling MMF_VM_MERGE_ANY for storage keys in s390

In the s390 architecture when storage keys are used, the
MMF_VM_MERGE_ANY will be disabled.

Link: https://lkml.kernel.org/r/20230418051342.1919757-1-shr@devkernel.io
Link: https://lkml.kernel.org/r/20230418051342.1919757-2-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

prctl: add PR_GET_AUXV to copy auxv to userspace

If a library wants to get information from auxv (for instance,
AT_HWCAP/AT_HWCAP2), it has a few options, none of them perfectly reliable
or ideal:

- Be main or the pre-main startup code, and grub through the stack above
main. Doesn't work for a library.
- Call libc getauxval. Not ideal for libraries that are trying to be
libc-independent and/or don't otherwise require anything from other
libraries.
- Open and read /proc/self/auxv. Doesn't work for libraries that may run
in arbitrarily constrained environments that may not have /proc
mounted (e.g. libraries that might be used by an init program or a
container setup tool).
- Assume you're on the main thread and still on the original stack, and
try to walk the stack upwards, hoping to find auxv. Extremely bad
idea.
- Ask the caller to pass auxv in for you. Not ideal for a user-friendly
library, and then your caller may have the same problem.

Add a prctl that copies current->mm->saved_auxv to a userspace buffer.

Link: https://lkml.kernel.org/r/d81864a7f7f43bca6afa2a09fc2e850e4050ab42.1680611394.git.josh@joshtriplett.org
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kernel/sys.c: fix and improve control flow in __sys_setres[ug]id()

Linux Security Modules (LSMs) that implement the "capable" hook will
usually emit an access denial message to the audit log whenever they
"block" the current task from using the given capability based on their
security policy.

The occurrence of a denial is used as an indication that the given task
has attempted an operation that requires the given access permission, so
the callers of functions that perform LSM permission checks must take care
to avoid calling them too early (before it is decided if the permission is
actually needed to perform the requested operation).

The __sys_setres[ug]id() functions violate this convention by first
calling ns_capable_setid() and only then checking if the operation
requires the capability or not. It means that any caller that has the
capability granted by DAC (task's capability set) but not by MAC (LSMs)
will generate a "denied" audit record, even if is doing an operation for
which the capability is not required.

Fix this by reordering the checks such that ns_capable_setid() is checked
last and -EPERM is returned immediately if it returns false.

While there, also do two small optimizations:
* move the capability check before prepare_creds() and
* bail out early in case of a no-op.

Link: https://lkml.kernel.org/r/20230217162154.837549-1-omosnace@redhat.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: implement memory-deny-write-execute as a prctl

Patch series "mm: In-kernel support for memory-deny-write-execute (MDWE)",
v2.

The background to this is that systemd has a configuration option called
MemoryDenyWriteExecute [2], implemented as a SECCOMP BPF filter. Its aim
is to prevent a user task from inadvertently creating an executable
mapping that is (or was) writeable. Since such BPF filter is stateless,
it cannot detect mappings that were previously writeable but subsequently
changed to read-only. Therefore the filter simply rejects any
mprotect(PROT_EXEC). The side-effect is that on arm64 with BTI support
(Branch Target Identification), the dynamic loader cannot change an ELF
section from PROT_EXEC to PROT_EXEC|PROT_BTI using mprotect(). For
libraries, it can resort to unmapping and re-mapping but for the main
executable it does not have a file descriptor. The original bug report in
the Red Hat bugzilla - [3] - and subsequent glibc workaround for libraries
- [4].

This series adds in-kernel support for this feature as a prctl
PR_SET_MDWE, that is inherited on fork(). The prctl denies PROT_WRITE |
PROT_EXEC mappings. Like the systemd BPF filter it also denies adding
PROT_EXEC to mappings. However unlike the BPF filter it only denies it if
the mapping didn't previous have PROT_EXEC. This allows to PROT_EXEC ->
PROT_EXEC | PROT_BTI with mprotect(), which is a problem with the BPF
filter.


This patch (of 2):

The aim of such policy is to prevent a user task from creating an
executable mapping that is also writeable.

An example of mmap() returning -EACCESS if the policy is enabled:

mmap(0, size, PROT_READ | PROT_WRITE | PROT_EXEC, flags, 0, 0);

Similarly, mprotect() would return -EACCESS below:

addr = mmap(0, size, PROT_READ | PROT_EXEC, flags, 0, 0);
mprotect(addr, size, PROT_READ | PROT_WRITE | PROT_EXEC);

The BPF filter that systemd MDWE uses is stateless, and disallows
mprotect() with PROT_EXEC completely. This new prctl allows PROT_EXEC to
be enabled if it was already PROT_EXEC, which allows the following case:

addr = mmap(0, size, PROT_READ | PROT_EXEC, flags, 0, 0);
mprotect(addr, size, PROT_READ | PROT_EXEC | PROT_BTI);

where PROT_BTI enables branch tracking identification on arm64.

Link: https://lkml.kernel.org/r/20230119160344.54358-1-joey.gouly@arm.com
Link: https://lkml.kernel.org/r/20230119160344.54358-2-joey.gouly@arm.com
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: nd <nd@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Topi Miettinen <toiwoton@gmail.com>
Cc: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

prlimit: do_prlimit needs to have a speculation check

do_prlimit() adds the user-controlled resource value to a pointer that
will subsequently be dereferenced. In order to help prevent this
codepath from being used as a spectre "gadget" a barrier needs to be
added after checking the range.

Reported-by: Jordy Zomer <jordyzomer@google.com>
Tested-by: Jordy Zomer <jordyzomer@google.com>
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

utsname: contribute changes to RNG

On some small machines with little entropy, a quasi-unique hostname is
sometimes a relevant factor. I've seen, for example, 8 character
alpha-numeric serial numbers. In addition, the time at which the hostname
is set is usually a decent measurement of how long early boot took. So,
call add_device_randomness() on new hostnames, which feeds its arguments
to the RNG in addition to a fresh cycle counter.

Low cost hooks like this never hurt and can only ever help, and since
this costs basically nothing for an operation that is never a fast path,
this is an overall easy win.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ucounts: Split rlimit and ucount values and max values

Since the semantics of maximum rlimit values are different, it would be
better not to mix ucount and rlimit values. This will prevent the error
of using inc_count/dec_ucount for rlimit parameters.

This patch also renames the functions to emphasize the lack of
connection between rlimit and ucount.

v3:
- Fix BUG:KASAN:use-after-free_in_dec_ucount.

v2:
- Fix the array-index-out-of-bounds that was found by the lkp project.

Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Link: https://lkml.kernel.org/r/20220518171730.l65lmnnjtnxnftpq@example.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

arm64/sme: Implement vector length configuration prctl()s

As for SVE provide a prctl() interface which allows processes to
configure their SME vector length.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-12-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

prlimit: do not grab the tasklist_lock

Unnecessarily grabbing the tasklist_lock can be a scalability bottleneck
for workloads that also must grab the tasklist_lock for waiting,
killing, and cloning.

The tasklist_lock was grabbed to protect tsk->sighand from disappearing
(becoming NULL). tsk->signal was already protected by holding a
reference to tsk.

update_rlimit_cpu() assumed tsk->sighand != NULL. With this commit, it
attempts to lock_task_sighand(). However, this means that
update_rlimit_cpu() can fail. This only happens when a task is exiting.
Note that during exec, sighand may *change*, but it will not be NULL.

Prior to this commit, the do_prlimit() ensured that update_rlimit_cpu()
would not fail by read locking the tasklist_lock and checking tsk->sighand
!= NULL.

If update_rlimit_cpu() fails, there may be other tasks that are not
exiting that share tsk->signal. However, the group_leader is the last
task to be released, so if we cannot update_rlimit_cpu(group_leader),
then the entire process is exiting.

The only other caller of update_rlimit_cpu() is
selinux_bprm_committing_creds(). It has tsk == current, so
update_rlimit_cpu() cannot fail (current->sighand cannot disappear
until current exits).

This change resulted in a 14% speedup on a microbenchmark where parents
kill and wait on their children, and children getpriority, setpriority,
and getrlimit.

Signed-off-by: Barret Rhoden <brho@google.com>
Link: https://lkml.kernel.org/r/20220106172041.522167-4-brho@google.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

prlimit: make do_prlimit() static

There are no other callers in the kernel.

Fixed up a comment format and whitespace issue when moving do_prlimit()
higher in sys.c.

Signed-off-by: Barret Rhoden <brho@google.com>
Link: https://lkml.kernel.org/r/20220106172041.522167-3-brho@google.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

mm: refactor vm_area_struct::anon_vma_name usage code

Avoid mixing strings and their anon_vma_name referenced pointers by
using struct anon_vma_name whenever possible. This simplifies the code
and allows easier sharing of anon_vma_name structures when they
represent the same name.

[surenb@google.com: fix comment]

Link: https://lkml.kernel.org/r/20220223153613.835563-1-surenb@google.com
Link: https://lkml.kernel.org/r/20220224231834.1481408-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Colin Cross <ccross@google.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Alexey Gladkov <legion@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Chris Hyser <chris.hyser@oracle.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Xiaofeng Cao <caoxiaofeng@yulong.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ucounts: Move RLIMIT_NPROC handling after set_user

During set*id() which cred->ucounts to charge the the current process
to is not known until after set_cred_ucounts. So move the
RLIMIT_NPROC checking into a new helper flag_nproc_exceeded and call
flag_nproc_exceeded after set_cred_ucounts.

This is very much an arbitrary subset of the places where we currently
change the RLIMIT_NPROC accounting, designed to preserve the existing
logic.

Fixing the existing logic will be the subject of another series of
changes.

Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220216155832.680775-4-ebiederm@xmission.com
Fixes: 21d1c5e386bc ("Reimplement RLIMIT_NPROC on top of ucounts")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

rlimit: Fix RLIMIT_NPROC enforcement failure caused by capability calls in set_user

Solar Designer <solar@openwall.com> wrote:
> I'm not aware of anyone actually running into this issue and reporting
> it. The systems that I personally know use suexec along with rlimits
> still run older/distro kernels, so would not yet be affected.
>
> So my mention was based on my understanding of how suexec works, and
> code review. Specifically, Apache httpd has the setting RLimitNPROC,
> which makes it set RLIMIT_NPROC:
>
> https://httpd.apache.org/docs/2.4/mod/core.html#rlimitnproc
>
> The above documentation for it includes:
>
> "This applies to processes forked from Apache httpd children servicing
> requests, not the Apache httpd children themselves. This includes CGI
> scripts and SSI exec commands, but not any processes forked from the
> Apache httpd parent, such as piped logs."
>
> In code, there are:
>
> ./modules/generators/mod_cgid.c: ( (cgid_req.limits.limit_nproc_set) && ((rc = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC,
> ./modules/generators/mod_cgi.c: ((rc = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC,
> ./modules/filters/mod_ext_filter.c: rv = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC, conf->limit_nproc);
>
> For example, in mod_cgi.c this is in run_cgi_child().
>
> I think this means an httpd child sets RLIMIT_NPROC shortly before it
> execs suexec, which is a SUID root program. suexec then switches to the
> target user and execs the CGI script.
>
> Before 2863643fb8b9, the setuid() in suexec would set the flag, and the
> target user's process count would be checked against RLIMIT_NPROC on
> execve(). After 2863643fb8b9, the setuid() in suexec wouldn't set the
> flag because setuid() is (naturally) called when the process is still
> running as root (thus, has those limits bypass capabilities), and
> accordingly execve() would not check the target user's process count
> against RLIMIT_NPROC.

In commit 2863643fb8b9 ("set_user: add capability check when
rlimit(RLIMIT_NPROC) exceeds") capable calls were added to set_user to
make it more consistent with fork. Unfortunately because of call site
differences those capable calls were checking the credentials of the
user before set*id() instead of after set*id().

This breaks enforcement of RLIMIT_NPROC for applications that set the
rlimit and then call set*id() while holding a full set of
capabilities. The capabilities are only changed in the new credential
in security_task_fix_setuid().

The code in apache suexec appears to follow this pattern.

Commit 909cc4ae86f3 ("[PATCH] Fix two bugs with process limits
(RLIMIT_NPROC)") where this check was added describes the targes of this
capability check as:

2/ When a root-owned process (e.g. cgiwrap) sets up process limits and then
calls setuid, the setuid should fail if the user would then be running
more than rlim_cur[RLIMIT_NPROC] processes, but it doesn't. This patch
adds an appropriate test. With this patch, and per-user process limit
imposed in cgiwrap really works.

So the original use case of this check also appears to match the broken
pattern.

Restore the enforcement of RLIMIT_NPROC by removing the bad capable
checks added in set_user. This unfortunately restores the
inconsistent state the code has been in for the last 11 years, but
dealing with the inconsistencies looks like a larger problem.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20210907213042.GA22626@openwall.com/
Link: https://lkml.kernel.org/r/20220212221412.GA29214@openwall.com
Link: https://lkml.kernel.org/r/20220216155832.680775-1-ebiederm@xmission.com
Fixes: 2863643fb8b9 ("set_user: add capability check when rlimit(RLIMIT_NPROC) exceeds")
History-Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Reviewed-by: Solar Designer <solar@openwall.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

kernel/sys.c: only take tasklist_lock for get/setpriority(PRIO_PGRP)

PRIO_PGRP needs the tasklist_lock mainly to serialize vs setpgid(2), to
protect against any concurrent change_pid(PIDTYPE_PGID) that can move
the task from one hlist to another while iterating.

However, the remaining can only rely only on RCU:

PRIO_PROCESS only does the task lookup and never iterates over tasklist
and we already have an rcu-aware stable pointer.

PRIO_USER is already racy vs setuid(2) so with creds being rcu
protected, we can end up seeing stale data. When removing the
tasklist_lock there can be a race with (i) fork but this is benign as
the child's nice is inherited and the new task is not observable by the
user yet either, hence the return semantics do not differ. And (ii) a
race with exit, which is a small window and can cause us to miss a task
which was removed from the list and it had the highest nice.

Similarly change the buggy do_each_thread/while_each_thread combo in
PRIO_USER for the rcu-safe for_each_process_thread flavor, which doesn't
make use of next_thread/p->thread_group.

[akpm@linux-foundation.org: coding style fixes]

Link: https://lkml.kernel.org/r/20211210182250.43734-1-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: add a field to store names for private anonymous memory

In many userspace applications, and especially in VM based applications
like Android uses heavily, there are multiple different allocators in
use. At a minimum there is libc malloc and the stack, and in many cases
there are libc malloc, the stack, direct syscalls to mmap anonymous
memory, and multiple VM heaps (one for small objects, one for big
objects, etc.). Each of these layers usually has its own tools to
inspect its usage; malloc by compiling a debug version, the VM through
heap inspection tools, and for direct syscalls there is usually no way
to track them.

On Android we heavily use a set of tools that use an extended version of
the logic covered in Documentation/vm/pagemap.txt to walk all pages
mapped in userspace and slice their usage by process, shared (COW) vs.
unique mappings, backing, etc. This can account for real physical
memory usage even in cases like fork without exec (which Android uses
heavily to share as many private COW pages as possible between
processes), Kernel SamePage Merging, and clean zero pages. It produces
a measurement of the pages that only exist in that process (USS, for
unique), and a measurement of the physical memory usage of that process
with the cost of shared pages being evenly split between processes that
share them (PSS).

If all anonymous memory is indistinguishable then figuring out the real
physical memory usage (PSS) of each heap requires either a pagemap
walking tool that can understand the heap debugging of every layer, or
for every layer's heap debugging tools to implement the pagemap walking
logic, in which case it is hard to get a consistent view of memory
across the whole system.

Tracking the information in userspace leads to all sorts of problems.
It either needs to be stored inside the process, which means every
process has to have an API to export its current heap information upon
request, or it has to be stored externally in a filesystem that somebody
needs to clean up on crashes. It needs to be readable while the process
is still running, so it has to have some sort of synchronization with
every layer of userspace. Efficiently tracking the ranges requires
reimplementing something like the kernel vma trees, and linking to it
from every layer of userspace. It requires more memory, more syscalls,
more runtime cost, and more complexity to separately track regions that
the kernel is already tracking.

This patch adds a field to /proc/pid/maps and /proc/pid/smaps to show a
userspace-provided name for anonymous vmas. The names of named
anonymous vmas are shown in /proc/pid/maps and /proc/pid/smaps as
[anon:<name>].

Userspace can set the name for a region of memory by calling

prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name)

Setting the name to NULL clears it. The name length limit is 80 bytes
including NUL-terminator and is checked to contain only printable ascii
characters (including space), except '[',']','\','$' and '`'.

Ascii strings are being used to have a descriptive identifiers for vmas,
which can be understood by the users reading /proc/pid/maps or
/proc/pid/smaps. Names can be standardized for a given system and they
can include some variable parts such as the name of the allocator or a
library, tid of the thread using it, etc.

The name is stored in a pointer in the shared union in vm_area_struct
that points to a null terminated string. Anonymous vmas with the same
name (equivalent strings) and are otherwise mergeable will be merged.
The name pointers are not shared between vmas even if they contain the
same name. The name pointer is stored in a union with fields that are
only used on file-backed mappings, so it does not increase memory usage.

CONFIG_ANON_VMA_NAME kernel configuration is introduced to enable this
feature. It keeps the feature disabled by default to prevent any
additional memory overhead and to avoid confusing procfs parsers on
systems which are not ready to support named anonymous vmas.

The patch is based on the original patch developed by Colin Cross, more
specifically on its latest version [1] posted upstream by Sumit Semwal.
It used a userspace pointer to store vma names. In that design, name
pointers could be shared between vmas. However during the last
upstreaming attempt, Kees Cook raised concerns [2] about this approach
and suggested to copy the name into kernel memory space, perform
validity checks [3] and store as a string referenced from
vm_area_struct.

One big concern is about fork() performance which would need to strdup
anonymous vma names. Dave Hansen suggested experimenting with
worst-case scenario of forking a process with 64k vmas having longest
possible names [4]. I ran this experiment on an ARM64 Android device
and recorded a worst-case regression of almost 40% when forking such a
process.

This regression is addressed in the followup patch which replaces the
pointer to a name with a refcounted structure that allows sharing the
name pointer between vmas of the same name. Instead of duplicating the
string during fork() or when splitting a vma it increments the refcount.

[1] https://lore.kernel.org/linux-mm/20200901161459.11772-4-sumit.semwal@linaro.org/
[2] https://lore.kernel.org/linux-mm/202009031031.D32EF57ED@keescook/
[3] https://lore.kernel.org/linux-mm/202009031022.3834F692@keescook/
[4] https://lore.kernel.org/linux-mm/5d0358ab-8c47-2f5f-8e43-23b89d6a8e95@intel.com/

Changes for prctl(2) manual page (in the options section):

PR_SET_VMA
Sets an attribute specified in arg2 for virtual memory areas
starting from the address specified in arg3 and spanning the
size specified in arg4. arg5 specifies the value of the attribute
to be set. Note that assigning an attribute to a virtual memory
area might prevent it from being merged with adjacent virtual
memory areas due to the difference in that attribute's value.

Currently, arg2 must be one of:

PR_SET_VMA_ANON_NAME
Set a name for anonymous virtual memory areas. arg5 should
be a pointer to a null-terminated string containing the
name. The name length including null byte cannot exceed
80 bytes. If arg5 is NULL, the name of the appropriate
anonymous virtual memory areas will be reset. The name
can contain only printable ascii characters (including
space), except '[',']','\','$' and '`'.

This feature is available only if the kernel is built with
the CONFIG_ANON_VMA_NAME option enabled.

[surenb@google.com: docs: proc.rst: /proc/PID/maps: fix malformed table]
Link: https://lkml.kernel.org/r/20211123185928.2513763-1-surenb@google.com
[surenb: rebased over v5.15-rc6, replaced userpointer with a kernel copy,
added input sanitization and CONFIG_ANON_VMA_NAME config. The bulk of the
work here was done by Colin Cross, therefore, with his permission, keeping
him as the author]

Link: https://lkml.kernel.org/r/20211019215511.3771969-2-surenb@google.com
Signed-off-by: Colin Cross <ccross@google.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Glauber <jan.glauber@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rob Landley <rob@landley.net>
Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: Shaohua Li <shli@fusionio.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl: allow to setup brk for et_dyn executables

Keno Fischer reported that when a binray loaded via ld-linux-x the
prctl(PR_SET_MM_MAP) doesn't allow to setup brk value because it lays
before mm:end_data.

For example a test program shows

| # ~/t
|
| start_code 401000
| end_code 401a15
| start_stack 7ffce4577dd0
| start_data 403e10
| end_data 40408c
| start_brk b5b000
| sbrk(0) b5b000

and when executed via ld-linux

| # /lib64/ld-linux-x86-64.so.2 ~/t
|
| start_code 7fc25b0a4000
| end_code 7fc25b0c4524
| start_stack 7fffcc6b2400
| start_data 7fc25b0ce4c0
| end_data 7fc25b0cff98
| start_brk 55555710c000
| sbrk(0) 55555710c000

This of course prevent criu from restoring such programs. Looking into
how kernel operates with brk/start_brk inside brk() syscall I don't see
any problem if we allow to setup brk/start_brk without checking for
end_data. Even if someone pass some weird address here on a purpose then
the worst possible result will be an unexpected unmapping of existing vma
(own vma, since prctl works with the callers memory) but test for
RLIMIT_DATA is still valid and a user won't be able to gain more memory in
case of expanding VMAs via new values shipped with prctl call.

Link: https://lkml.kernel.org/r/20210121221207.GB2174@grain
Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing direct loader exec")
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reported-by: Keno Fischer <keno@juliacomputing.com>
Acked-by: Andrey Vagin <avagin@gmail.com>
Tested-by: Andrey Vagin <avagin@gmail.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/fork: factor out replacing the current MM exe_file

Let's factor the main logic out into replace_mm_exe_file(), such that
all mm->exe_file logic is contained in kernel/fork.c.

While at it, perform some simple cleanups that are possible now that
we're simplifying the individual functions.

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

set_user: add capability check when rlimit(RLIMIT_NPROC) exceeds

in copy_process(): non root users but with capability CAP_SYS_RESOURCE
or CAP_SYS_ADMIN will clean PF_NPROC_EXCEEDED flag even
rlimit(RLIMIT_NPROC) exceeds. Add the same capability check logic here.

Align the permission checks in copy_process() and set_user(). In
copy_process() CAP_SYS_RESOURCE or CAP_SYS_ADMIN capable users will be
able to circumvent and clear the PF_NPROC_EXCEEDED flag whereas they
aren't able to the same in set_user(). There's no obvious logic to this
and trying to unearth the reason in the thread didn't go anywhere.

The gist seems to be that this code wants to make sure that a program
can't successfully exec if it has gone through a set*id() transition
while exceeding its RLIMIT_NPROC.
A capable but non-INIT_USER caller getting PF_NPROC_EXCEEDED set during
a set*id() transition wouldn't be able to exec right away if they still
exceed their RLIMIT_NPROC at the time of exec. So their exec would fail
in fs/exec.c:

if ((current->flags & PF_NPROC_EXCEEDED) &&
is_ucounts_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
retval = -EAGAIN;
goto out_ret;
}

However, if the caller were to fork() right after the set*id()
transition but before the exec while still exceeding their RLIMIT_NPROC
then they would get PF_NPROC_EXCEEDED cleared (while the child would
inherit it):

retval = -EAGAIN;
if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
if (p->real_cred->user != INIT_USER &&
!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
goto bad_fork_free;
}
current->flags &= ~PF_NPROC_EXCEEDED;

which means a subsequent exec by the capable caller would now succeed
even though they could still exceed their RLIMIT_NPROC limit. This seems
inconsistent. Allow a CAP_SYS_ADMIN or CAP_SYS_RESOURCE capable user to
avoid PF_NPROC_EXCEEDED as they already can in copy_process().

Cc: peterz@infradead.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, Ran Xiaokai <ran.xiaokai@zte.com.cn>, , ,

Link: https://lore.kernel.org/r/20210728072629.530435-1-ran.xiaokai@zte.com.cn
Cc: Neil Brown <neilb@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: James Morris <jamorris@linux.microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

sched: prctl() core-scheduling interface

This patch provides support for setting and copying core scheduling
'task cookies' between threads (PID), processes (TGID), and process
groups (PGID).

The value of core scheduling isn't that tasks don't share a core,
'nosmt' can do that. The value lies in exploiting all the sharing
opportunities that exist to recover possible lost performance and that
requires a degree of flexibility in the API.

From a security perspective (and there are others), the thread,
process and process group distinction is an existent hierarchal
categorization of tasks that reflects many of the security concerns
about 'data sharing'. For example, protecting against cache-snooping
by a thread that can just read the memory directly isn't all that
useful.

With this in mind, subcommands to CREATE/SHARE (TO/FROM) provide a
mechanism to create and share cookies. CREATE/SHARE_TO specify a
target pid with enum pidtype used to specify the scope of the targeted
tasks. For example, PIDTYPE_TGID will share the cookie with the
process and all of it's threads as typically desired in a security
scenario.

API:

prctl(PR_SCHED_CORE, PR_SCHED_CORE_GET, tgtpid, pidtype, &cookie)
prctl(PR_SCHED_CORE, PR_SCHED_CORE_CREATE, tgtpid, pidtype, NULL)
prctl(PR_SCHED_CORE, PR_SCHED_CORE_SHARE_TO, tgtpid, pidtype, NULL)
prctl(PR_SCHED_CORE, PR_SCHED_CORE_SHARE_FROM, srcpid, pidtype, NULL)

where 'tgtpid/srcpid == 0' implies the current process and pidtype is
kernel enum pid_type {PIDTYPE_PID, PIDTYPE_TGID, PIDTYPE_PGID, ...}.

For return values, EINVAL, ENOMEM are what they say. ESRCH means the
tgtpid/srcpid was not found. EPERM indicates lack of PTRACE permission
access to tgtpid/srcpid. ENODEV indicates your machines lacks SMT.

[peterz: complete rewrite]
Signed-off-by: Chris Hyser <chris.hyser@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Don Hiatt <dhiatt@digitalocean.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210422123309.039845339@infradead.org

Reimplement RLIMIT_NPROC on top of ucounts

The rlimit counter is tied to uid in the user_namespace. This allows
rlimit values to be specified in userns even if they are already
globally exceeded by the user. However, the value of the previous
user_namespaces cannot be exceeded.

To illustrate the impact of rlimits, let's say there is a program that
does not fork. Some service-A wants to run this program as user X in
multiple containers. Since the program never fork the service wants to
set RLIMIT_NPROC=1.

service-A
\- program (uid=1000, container1, rlimit_nproc=1)
\- program (uid=1000, container2, rlimit_nproc=1)

The service-A sets RLIMIT_NPROC=1 and runs the program in container1.
When the service-A tries to run a program with RLIMIT_NPROC=1 in
container2 it fails since user X already has one running process.

We cannot use existing inc_ucounts / dec_ucounts because they do not
allow us to exceed the maximum for the counter. Some rlimits can be
overlimited by root or if the user has the appropriate capability.

Changelog

v11:
* Change inc_rlimit_ucounts() which now returns top value of ucounts.
* Drop inc_rlimit_ucounts_and_test() because the return code of
inc_rlimit_ucounts() can be checked.

Signed-off-by: Alexey Gladkov <legion@kernel.org>
Link: https://lkml.kernel.org/r/c5286a8aa16d2d698c222f7532f3d735c82bc6bc.1619094428.git.legion@kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Add a reference to ucounts for each cred

For RLIMIT_NPROC and some other rlimits the user_struct that holds the
global limit is kept alive for the lifetime of a process by keeping it
in struct cred. Adding a pointer to ucounts in the struct cred will
allow to track RLIMIT_NPROC not only for user in the system, but for
user in the user_namespace.

Updating ucounts may require memory allocation which may fail. So, we
cannot change cred.ucounts in the commit_creds() because this function
cannot fail and it should always return 0. For this reason, we modify
cred.ucounts before calling the commit_creds().

Changelog

v6:
* Fix null-ptr-deref in is_ucounts_overlimit() detected by trinity. This
error was caused by the fact that cred_alloc_blank() left the ucounts
pointer empty.

Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Link: https://lkml.kernel.org/r/b37aaef28d8b9b0d757e07ba6dd27281bbe39259.1619094428.git.legion@kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

kernel/sys.c: fix typo

change 'infite' to 'infinite'
change 'concurent' to 'concurrent'
change 'memvers' to 'members'
change 'decendants' to 'descendants'
change 'argumets' to 'arguments'

Link: https://lkml.kernel.org/r/20210316112904.10661-1-cxfcosmos@gmail.com
Signed-off-by: Xiaofeng Cao <caoxiaofeng@yulong.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS)

This change introduces a prctl that allows the user program to control
which PAC keys are enabled in a particular task. The main reason
why this is useful is to enable a userspace ABI that uses PAC to
sign and authenticate function pointers and other pointers exposed
outside of the function, while still allowing binaries conforming
to the ABI to interoperate with legacy binaries that do not sign or
authenticate pointers.

The idea is that a dynamic loader or early startup code would issue
this prctl very early after establishing that a process may load legacy
binaries, but before executing any PAC instructions.

This change adds a small amount of overhead to kernel entry and exit
due to additional required instruction sequences.

On a DragonBoard 845c (Cortex-A75) with the powersave governor, the
overhead of similar instruction sequences was measured as 4.9ns when
simulating the common case where IA is left enabled, or 43.7ns when
simulating the uncommon case where IA is disabled. These numbers can
be seen as the worst case scenario, since in more realistic scenarios
a better performing governor would be used and a newer chip would be
used that would support PAC unlike Cortex-A75 and would be expected
to be faster than Cortex-A75.

On an Apple M1 under a hypervisor, the overhead of the entry/exit
instruction sequences introduced by this patch was measured as 0.3ns
in the case where IA is left enabled, and 33.0ns in the case where
IA is disabled.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://linux-review.googlesource.com/id/Ibc41a5e6a76b275efbaa126b31119dc197b927a5
Link: https://lore.kernel.org/r/d6609065f8f40397a4124654eb68c9f490b4d477.1616123271.git.pcc@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

prctl: fix PR_SET_MM_AUXV kernel stack leak

Doing a

prctl(PR_SET_MM, PR_SET_MM_AUXV, addr, 1);

will copy 1 byte from userspace to (quite big) on-stack array
and then stash everything to mm->saved_auxv.
AT_NULL terminator will be inserted at the very end.

/proc/*/auxv handler will find that AT_NULL terminator
and copy original stack contents to userspace.

This devious scheme requires CAP_SYS_RESOURCE.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kbuild: simplify access to the kernel's version

Instead of storing the version in a single integer and having various
kernel (and userspace) code how it's constructed, export individual
(major, patchlevel, sublevel) components and simplify kernel code that
uses it.

This should also make it easier on userspace.

Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

fs: add file and path permissions helpers

Add two simple helpers to check permissions on a file and path
respectively and convert over some callers. It simplifies quite a few
codepaths and also reduces the churn in later patches quite a bit.
Christoph also correctly points out that this makes codepaths (e.g.
ioctls) way easier to follow that would otherwise have to do more
complex argument passing than necessary.

Link: https://lore.kernel.org/r/20210121131959.646623-4-christian.brauner@ubuntu.com
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

fs: Remove dcookies support

The dcookies stuff was only used by the kernel's old oprofile code. Now
that oprofile's support is removed from the kernel, there is no need for
dcookies as well. Remove it.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Robert Richter <rric@kernel.org>
Acked-by: William Cohen <wcohen@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Thomas Gleixner <tglx@linutronix.de>

kernel: Implement selective syscall userspace redirection

Introduce a mechanism to quickly disable/enable syscall handling for a
specific process and redirect to userspace via SIGSYS. This is useful
for processes with parts that require syscall redirection and parts that
don't, but who need to perform this boundary crossing really fast,
without paying the cost of a system call to reconfigure syscall handling
on each boundary transition. This is particularly important for Windows
games running over Wine.

The proposed interface looks like this:

prctl(PR_SET_SYSCALL_USER_DISPATCH, <op>, <off>, <length>, [selector])

The range [<offset>,<offset>+<length>) is a part of the process memory
map that is allowed to by-pass the redirection code and dispatch
syscalls directly, such that in fast paths a process doesn't need to
disable the trap nor the kernel has to check the selector. This is
essential to return from SIGSYS to a blocked area without triggering
another SIGSYS from rt_sigreturn.

selector is an optional pointer to a char-sized userspace memory region
that has a key switch for the mechanism. This key switch is set to
either PR_SYS_DISPATCH_ON, PR_SYS_DISPATCH_OFF to enable and disable the
redirection without calling the kernel.

The feature is meant to be set per-thread and it is disabled on
fork/clone/execv.

Internally, this doesn't add overhead to the syscall hot path, and it
requires very little per-architecture support. I avoided using seccomp,
even though it duplicates some functionality, due to previous feedback
that maybe it shouldn't mix with seccomp since it is not a security
mechanism. And obviously, this should never be considered a security
mechanism, since any part of the program can by-pass it by using the
syscall dispatcher.

For the sysinfo benchmark, which measures the overhead added to
executing a native syscall that doesn't require interception, the
overhead using only the direct dispatcher region to issue syscalls is
pretty much irrelevant. The overhead of using the selector goes around
40ns for a native (unredirected) syscall in my system, and it is (as
expected) dominated by the supervisor-mode user-address access. In
fact, with SMAP off, the overhead is consistently less than 5ns on my
test box.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201127193238.821364-4-krisman@collabora.com

kernel/sys.c: fix prototype of prctl_get_tid_address()

tid_addr is not a "pointer to (pointer to int in userspace)"; it is in
fact a "pointer to (pointer to int in userspace) in userspace". So
sparse rightfully complains about passing a kernel pointer to
put_user().

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: replace do_brk with do_brk_flags in comment of prctl_set_mm_map()

Replace do_brk with do_brk_flags in comment of prctl_set_mm_map(), since
do_brk was removed in following commit.

Fixes: bb177a732c4369 ("mm: do not bug_on on incorrect length in __mm_populate()")
Signed-off-by: Liao Pingfang <liao.pingfang@zte.com.cn>
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/1600650751-43127-1-git-send-email-wang.yi59@zte.com.cn
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

LSM: Signal to SafeSetID when setting group IDs

For SafeSetID to properly gate set*gid() calls, it needs to know whether
ns_capable() is being called from within a sys_set*gid() function or is
being called from elsewhere in the kernel. This allows SafeSetID to deny
CAP_SETGID to restricted groups when they are attempting to use the
capability for code paths other than updating GIDs (e.g. setting up
userns GID mappings). This is the identical approach to what is
currently done for CAP_SETUID.

NOTE: We also add signaling to SafeSetID from the setgroups() syscall,
as we have future plans to restrict a process' ability to set
supplementary groups in addition to what is added in this series for
restricting setting of the primary group.

Signed-off-by: Thomas Cedeno <thomascedeno@google.com>
Signed-off-by: Micah Morton <mortonm@chromium.org>

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

sys: Convert to the new fallthrough notation

Switch from using the /* fall through */ comment style notation to the new,
preferred notation as outlined in our docs.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
[christian.brauner@ubuntu.com: rewrite commit message]
Link: https://lore.kernel.org/r/20200814085718.40326-1-linmiaohe@huawei.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

prctl: exe link permission error changed from -EINVAL to -EPERM

This brings consistency with the rest of the prctl() syscall where
-EPERM is returned when failing a capability check.

Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com>
Signed-off-by: Adrian Reber <areber@redhat.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Link: https://lore.kernel.org/r/20200719100418.2112740-7-areber@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

prctl: Allow local CAP_CHECKPOINT_RESTORE to change /proc/self/exe

Originally, only a local CAP_SYS_ADMIN could change the exe link,
making it difficult for doing checkpoint/restore without CAP_SYS_ADMIN.
This commit adds CAP_CHECKPOINT_RESTORE in addition to CAP_SYS_ADMIN
for permitting changing the exe link.

The following describes the history of the /proc/self/exe permission
checks as it may be difficult to understand what decisions lead to this
point.

* [1] May 2012: This commit introduces the ability of changing
/proc/self/exe if the user is CAP_SYS_RESOURCE capable.
In the related discussion [2], no clear thread model is presented for
what could happen if the /proc/self/exe changes multiple times, or why
would the admin be at the mercy of userspace.

* [3] Oct 2014: This commit introduces a new API to change
/proc/self/exe. The permission no longer checks for CAP_SYS_RESOURCE,
but instead checks if the current user is root (uid=0) in its local
namespace. In the related discussion [4] it is said that "Controlling
exe_fd without privileges may turn out to be dangerous. At least
things like tomoyo examine it for making policy decisions (see
tomoyo_manager())."

* [5] Dec 2016: This commit removes the restriction to change
/proc/self/exe at most once. The related discussion [6] informs that
the audit subsystem relies on the exe symlink, presumably
audit_log_d_path_exe() in kernel/audit.c.

* [7] May 2017: This commit changed the check from uid==0 to local
CAP_SYS_ADMIN. No discussion.

* [8] July 2020: A PoC to spoof any program's /proc/self/exe via ptrace
is demonstrated

Overall, the concrete points that were made to retain capability checks
around changing the exe symlink is that tomoyo_manager() and
audit_log_d_path_exe() uses the exe_file path.

Christian Brauner said that relying on /proc/<pid>/exe being immutable (or
guarded by caps) in a sake of security is a bit misleading. It can only
be used as a hint without any guarantees of what code is being executed
once execve() returns to userspace. Christian suggested that in the
future, we could call audit_log() or similar to inform the admin of all
exe link changes, instead of attempting to provide security guarantees
via permission checks. However, this proposed change requires the
understanding of the security implications in the tomoyo/audit subsystems.

[1] b32dfe377102 ("c/r: prctl: add ability to set new mm_struct::exe_file")
[2] https://lore.kernel.org/patchwork/patch/292515/
[3] f606b77f1a9e ("prctl: PR_SET_MM -- introduce PR_SET_MM_MAP operation")
[4] https://lore.kernel.org/patchwork/patch/479359/
[5] 3fb4afd9a504 ("prctl: remove one-shot limitation for changing exe link")
[6] https://lore.kernel.org/patchwork/patch/697304/
[7] 4d28df6152aa ("prctl: Allow local CAP_SYS_ADMIN changing exe_file")
[8] https://github.com/nviennot/run_as_exe

Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com>
Signed-off-by: Adrian Reber <areber@redhat.com>
Link: https://lore.kernel.org/r/20200719100418.2112740-6-areber@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

security: Add LSM hooks to set*gid syscalls

The SafeSetID LSM uses the security_task_fix_setuid hook to filter
set*uid() syscalls according to its configured security policy. In
preparation for adding analagous support in the LSM for set*gid()
syscalls, we add the requisite hook here. Tested by putting print
statements in the security_task_fix_setgid hook and seeing them get hit
during kernel boot.

Signed-off-by: Thomas Cedeno <thomascedeno@google.com>
Signed-off-by: Micah Morton <mortonm@chromium.org>

mmap locking API: convert mmap_sem comments

Convert comments that reference mmap_sem to reference mmap_lock instead.

[akpm@linux-foundation.org: fix up linux-next leftovers]
[akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil]
[akpm@linux-foundation.org: more linux-next fixups, per Michel]

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mmap locking API: use coccinelle to convert mmap_sem rwsem call sites

This change converts the existing mmap_sem rwsem calls to use the new mmap
locking API instead.

The change is generated using coccinelle with the following rule:

// spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir .

@@
expression mm;
@@
(
-init_rwsem
+mmap_init_lock
|
-down_write
+mmap_write_lock
|
-down_write_killable
+mmap_write_lock_killable
|
-down_write_trylock
+mmap_write_trylock
|
-up_write
+mmap_write_unlock
|
-downgrade_write
+mmap_write_downgrade
|
-down_read
+mmap_read_lock
|
-down_read_killable
+mmap_read_lock_killable
|
-down_read_trylock
+mmap_read_trylock
|
-up_read
+mmap_read_unlock
)
-(&mm->mmap_sem)
+(mm)

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/writeback: replace PF_LESS_THROTTLE with PF_LOCAL_THROTTLE

PF_LESS_THROTTLE exists for loop-back nfsd (and a similar need in the
loop block driver and callers of prctl(PR_SET_IO_FLUSHER)), where a
daemon needs to write to one bdi (the final bdi) in order to free up
writes queued to another bdi (the client bdi).

The daemon sets PF_LESS_THROTTLE and gets a larger allowance of dirty
pages, so that it can still dirty pages after other processses have been
throttled. The purpose of this is to avoid deadlock that happen when
the PF_LESS_THROTTLE process must write for any dirty pages to be freed,
but it is being thottled and cannot write.

This approach was designed when all threads were blocked equally,
independently on which device they were writing to, or how fast it was.
Since that time the writeback algorithm has changed substantially with
different threads getting different allowances based on non-trivial
heuristics. This means the simple "add 25%" heuristic is no longer
reliable.

The important issue is not that the daemon needs a *larger* dirty page
allowance, but that it needs a *private* dirty page allowance, so that
dirty pages for the "client" bdi that it is helping to clear (the bdi
for an NFS filesystem or loop block device etc) do not affect the
throttling of the daemon writing to the "final" bdi.

This patch changes the heuristic so that the task is not throttled when
the bdi it is writing to has a dirty page count below below (or equal
to) the free-run threshold for that bdi. This ensures it will always be
able to have some pages in flight, and so will not deadlock.

In a steady-state, it is expected that PF_LOCAL_THROTTLE tasks might
still be throttled by global threshold, but that is acceptable as it is
only the deadlock state that is interesting for this flag.

This approach of "only throttle when target bdi is busy" is consistent
with the other use of PF_LESS_THROTTLE in current_may_throttle(), were
it causes attention to be focussed only on the target bdi.

So this patch
- renames PF_LESS_THROTTLE to PF_LOCAL_THROTTLE,
- removes the 25% bonus that that flag gives, and
- If PF_LOCAL_THROTTLE is set, don't delay at all unless the
global and the local free-run thresholds are exceeded.

Note that previously realtime threads were treated the same as
PF_LESS_THROTTLE threads. This patch does *not* change the behvaiour
for real-time threads, so it is now different from the behaviour of nfsd
and loop tasks. I don't know what is wanted for realtime.

[akpm@linux-foundation.org: coding style fixes]
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Chuck Lever <chuck.lever@oracle.com> [nfsd]
Cc: Christoph Hellwig <hch@lst.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Link: http://lkml.kernel.org/r/87ftbf7gs3.fsf@notabene.neil.brown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

compat sysinfo(2): don't bother with field-by-field copyout

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

sys/sysinfo: Respect boottime inside time namespace

The sysinfo() syscall includes uptime in seconds but has no correction for
time namespaces which makes it inconsistent with the /proc/uptime inside of
a time namespace.

Add the missing time namespace adjustment call.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Link: https://lkml.kernel.org/r/20200303150638.7329-1-chrubis@suse.cz

prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim

There are several storage drivers like dm-multipath, iscsi, tcmu-runner,
amd nbd that have userspace components that can run in the IO path. For
example, iscsi and nbd's userspace deamons may need to recreate a socket
and/or send IO on it, and dm-multipath's daemon multipathd may need to
send SG IO or read/write IO to figure out the state of paths and re-set
them up.

In the kernel these drivers have access to GFP_NOIO/GFP_NOFS and the
memalloc_*_save/restore functions to control the allocation behavior,
but for userspace we would end up hitting an allocation that ended up
writing data back to the same device we are trying to allocate for.
The device is then in a state of deadlock, because to execute IO the
device needs to allocate memory, but to allocate memory the memory
layers want execute IO to the device.

Here is an example with nbd using a local userspace daemon that performs
network IO to a remote server. We are using XFS on top of the nbd device,
but it can happen with any FS or other modules layered on top of the nbd
device that can write out data to free memory. Here a nbd daemon helper
thread, msgr-worker-1, is performing a write/sendmsg on a socket to execute
a request. This kicks off a reclaim operation which results in a WRITE to
the nbd device and the nbd thread calling back into the mm layer.

[ 1626.609191] msgr-worker-1 D 0 1026 1 0x00004000
[ 1626.609193] Call Trace:
[ 1626.609195] ? __schedule+0x29b/0x630
[ 1626.609197] ? wait_for_completion+0xe0/0x170
[ 1626.609198] schedule+0x30/0xb0
[ 1626.609200] schedule_timeout+0x1f6/0x2f0
[ 1626.609202] ? blk_finish_plug+0x21/0x2e
[ 1626.609204] ? _xfs_buf_ioapply+0x2e6/0x410
[ 1626.609206] ? wait_for_completion+0xe0/0x170
[ 1626.609208] wait_for_completion+0x108/0x170
[ 1626.609210] ? wake_up_q+0x70/0x70
[ 1626.609212] ? __xfs_buf_submit+0x12e/0x250
[ 1626.609214] ? xfs_bwrite+0x25/0x60
[ 1626.609215] xfs_buf_iowait+0x22/0xf0
[ 1626.609218] __xfs_buf_submit+0x12e/0x250
[ 1626.609220] xfs_bwrite+0x25/0x60
[ 1626.609222] xfs_reclaim_inode+0x2e8/0x310
[ 1626.609224] xfs_reclaim_inodes_ag+0x1b6/0x300
[ 1626.609227] xfs_reclaim_inodes_nr+0x31/0x40
[ 1626.609228] super_cache_scan+0x152/0x1a0
[ 1626.609231] do_shrink_slab+0x12c/0x2d0
[ 1626.609233] shrink_slab+0x9c/0x2a0
[ 1626.609235] shrink_node+0xd7/0x470
[ 1626.609237] do_try_to_free_pages+0xbf/0x380
[ 1626.609240] try_to_free_pages+0xd9/0x1f0
[ 1626.609245] __alloc_pages_slowpath+0x3a4/0xd30
[ 1626.609251] ? ___slab_alloc+0x238/0x560
[ 1626.609254] __alloc_pages_nodemask+0x30c/0x350
[ 1626.609259] skb_page_frag_refill+0x97/0xd0
[ 1626.609274] sk_page_frag_refill+0x1d/0x80
[ 1626.609279] tcp_sendmsg_locked+0x2bb/0xdd0
[ 1626.609304] tcp_sendmsg+0x27/0x40
[ 1626.609307] sock_sendmsg+0x54/0x60
[ 1626.609308] ___sys_sendmsg+0x29f/0x320
[ 1626.609313] ? sock_poll+0x66/0xb0
[ 1626.609318] ? ep_item_poll.isra.15+0x40/0xc0
[ 1626.609320] ? ep_send_events_proc+0xe6/0x230
[ 1626.609322] ? hrtimer_try_to_cancel+0x54/0xf0
[ 1626.609324] ? ep_read_events_proc+0xc0/0xc0
[ 1626.609326] ? _raw_write_unlock_irq+0xa/0x20
[ 1626.609327] ? ep_scan_ready_list.constprop.19+0x218/0x230
[ 1626.609329] ? __hrtimer_init+0xb0/0xb0
[ 1626.609331] ? _raw_spin_unlock_irq+0xa/0x20
[ 1626.609334] ? ep_poll+0x26c/0x4a0
[ 1626.609337] ? tcp_tsq_write.part.54+0xa0/0xa0
[ 1626.609339] ? release_sock+0x43/0x90
[ 1626.609341] ? _raw_spin_unlock_bh+0xa/0x20
[ 1626.609342] __sys_sendmsg+0x47/0x80
[ 1626.609347] do_syscall_64+0x5f/0x1c0
[ 1626.609349] ? prepare_exit_to_usermode+0x75/0xa0
[ 1626.609351] entry_SYSCALL_64_after_hwframe+0x44/0xa9

This patch adds a new prctl command that daemons can use after they have
done their initial setup, and before they start to do allocations that
are in the IO path. It sets the PF_MEMALLOC_NOIO and PF_LESS_THROTTLE
flags so both userspace block and FS threads can use it to avoid the
allocation recursion and try to prevent from being throttled while
writing out data to free up memory.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Masato Suzuki <masato.suzuki@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Link: https://lore.kernel.org/r/20191112001900.9206-1-mchristi@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

kernel/sys.c: avoid copying possible padding bytes in copy_to_user

Initialization is not guaranteed to zero padding bytes so use an
explicit memset instead to avoid leaking any kernel content in any
possible padding bytes.

Link: http://lkml.kernel.org/r/dfa331c00881d61c8ee51577a082d8bebd61805c.camel@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Dan Carpenter <error27@gmail.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

y2038: rusage: use __kernel_old_timeval

There are two 'struct timeval' fields in 'struct rusage'.

Unfortunately the definition of timeval is now ambiguous when used in
user space with a libc that has a 64-bit time_t, and this also changes
the 'rusage' definition in user space in a way that is incompatible with
the system call interface.

While there is no good solution to avoid all ambiguity here, change
the definition in the kernel headers to be compatible with the kernel
ABI, using __kernel_old_timeval as an unambiguous base type.

In previous discussions, there was also a plan to add a replacement
for rusage based on 64-bit timestamps and nanosecond resolution,
i.e. 'struct __kernel_timespec'. I have patches for that as well,
if anyone thinks we should do that.

Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

posix-cpu-timers: Get rid of zero checks

Deactivation of the expiry cache is done by setting all clock caches to
0. That requires to have a check for zero in all places which update the
expiry cache:

if (cache == 0 || new < cache)
cache = new;

Use U64_MAX as the deactivated value, which allows to remove the zero
checks when updating the cache and reduces it to the obvious check:

if (new < cache)
cache = new;

This also removes the weird workaround in do_prlimit() which was required
to convert a RLIMIT_CPU value of 0 (immediate expiry) to 1 because handing
in 0 to the posix CPU timer code would have effectively disarmed it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192922.275086128@linutronix.de

rlimit: Rewrite non-sensical RLIMIT_CPU comment

The comment above the function which arms RLIMIT_CPU in the posix CPU timer
code makes no sense at all. It claims that the kernel does not return an
error code when it rejected the attempt to set RLIMIT_CPU. That's clearly
bogus as the code does an error check and the rlimit is only set and
activated when the permission checks are ok. In case of a rejection an
appropriate error code is returned.

This is a historical and outdated comment which got dragged along even when
the rlimit handling code was rewritten.

Replace it with an explanation why the setup function is not called when
the rlimit value is RLIM_INFINITY and how the 'disarming' is handled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192922.185511287@linutronix.de

arm64: Tighten the PR_{SET, GET}_TAGGED_ADDR_CTRL prctl() unused arguments

Require that arg{3,4,5} of the PR_{SET,GET}_TAGGED_ADDR_CTRL prctl and
arg2 of the PR_GET_TAGGED_ADDR_CTRL prctl() are zero rather than ignored
for future extensions.

Acked-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

arm64: Introduce prctl() options to control the tagged user addresses ABI

It is not desirable to relax the ABI to allow tagged user addresses into
the kernel indiscriminately. This patch introduces a prctl() interface
for enabling or disabling the tagged ABI with a global sysctl control
for preventing applications from enabling the relaxed ABI (meant for
testing user-space prctl() return error checking without reconfiguring
the kernel). The ABI properties are inherited by threads of the same
application and fork()'ed children but cleared on execve(). A Kconfig
option allows the overall disabling of the relaxed ABI.

The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle
MTE-specific settings like imprecise vs precise exceptions.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Will Deacon <will@kernel.org>

x86/mpx: Remove MPX APIs

MPX is being removed from the kernel due to a lack of support in the
toolchain going forward (gcc).

The first step is to remove the userspace-visible ABIs so that applications
will stop using it. The most visible one are the enable/disable prctl()s.
Remove them first.

This is the most minimal and least invasive change needed to ensure that
apps stop using MPX with new kernels.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190705175321.DB42F0AD@viggo.jf.intel.com

prctl_set_mm: downgrade mmap_sem to read lock

The commit a3b609ef9f8b ("proc read mm's {arg,env}_{start,end} with mmap
semaphore taken.") added synchronization of reading argument/environment
boundaries under mmap_sem. Later commit 88aa7cc688d4 ("mm: introduce
arg_lock to protect arg_start|end and env_start|end in mm_struct") avoided
the coarse use of mmap_sem in similar situations. But there still
remained two places that (mis)use mmap_sem.

get_cmdline should also use arg_lock instead of mmap_sem when it reads the
boundaries.

The second place that should use arg_lock is in prctl_set_mm. By
protecting the boundaries fields with the arg_lock, we can downgrade
mmap_sem to reader lock (analogous to what we already do in
prctl_set_mm_map).

[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/20190502125203.24014-3-mkoutny@suse.com
Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct")
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Co-developed-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl_set_mm: refactor checks from validate_prctl_map

Despite comment of validate_prctl_map claims there are no capability
checks, it is not completely true since commit 4d28df6152aa ("prctl: Allow
local CAP_SYS_ADMIN changing exe_file"). Extract the check out of the
function and make the function perform purely arithmetic checks.

This patch should not change any behavior, it is mere refactoring for
following patch.

[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/20190502125203.24014-2-mkoutny@suse.com
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: prctl: fix false positive in validate_prctl_map()

While validating new map we require the @start_data to be strictly less
than @end_data, which is fine for regular applications (this is why this
nit didn't trigger for that long). These members are set from executable
loaders such as elf handers, still it is pretty valid to have a loadable
data section with zero size in file, in such case the start_data is equal
to end_data once kernel loader finishes.

As a result when we're trying to restore such programs the procedure fails
and the kernel returns -EINVAL. From the image dump of a program:

| "mm_start_code": "0x400000",
| "mm_end_code": "0x8f5fb4",
| "mm_start_data": "0xf1bfb0",
| "mm_end_data": "0xf1bfb0",

Thus we need to change validate_prctl_map from strictly less to less or
equal operator use.

Link: http://lkml.kernel.org/r/20190408143554.GY1421@uranus.lan
Fixes: f606b77f1a9e3 ("prctl: PR_SET_MM -- introduce PR_SET_MM_MAP operation")
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Andrey Vagin <avagin@gmail.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys: annotate implicit fall through

There is a plan to build the kernel with -Wimplicit-fallthrough and this
place in the code produced a warning (W=1).

This commit remove the following warning:

kernel/sys.c:1748:6: warning: this statement may fall through [-Wimplicit-fallthrough=]

Link: http://lkml.kernel.org/r/20190114203347.17530-1-malat@debian.org
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

LSM: add SafeSetID module that gates setid calls

This change ensures that the set*uid family of syscalls in kernel/sys.c
(setreuid, setuid, setresuid, setfsuid) all call ns_capable_common with
the CAP_OPT_INSETID flag, so capability checks in the security_capable
hook can know whether they are being called from within a set*uid
syscall. This change is a no-op by itself, but is needed for the
proposed SafeSetID LSM.

Signed-off-by: Micah Morton <mortonm@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.morris@microsoft.com>

kernel/sys.c: Clarify that UNAME26 does not generate unique versions anymore

UNAME26 is a mechanism to report Linux's version as 2.6.x, for
compatibility with old/broken software. Due to the way it is
implemented, it would have to be updated after 5.0, to keep the
resulting versions unique. Linus Torvalds argued:

"Do we actually need this?

I'd rather let it bitrot, and just let it return random versions. It
will just start again at 2.4.60, won't it?

Anybody who uses UNAME26 for a 5.x kernel might as well think it's
still 4.x. The user space is so old that it can't possibly care about
differences between 4.x and 5.x, can it?

The only thing that matters is that it shows "2.4.<largeenough>",
which it will do regardless"

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Remove 'type' argument from access_ok() function

Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

- csky still had the old "verify_area()" name as an alias.

- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)

- microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arm64: add prctl control for resetting ptrauth keys

Add an arm64-specific prctl to allow a thread to reinitialize its
pointer authentication keys to random values. This can be useful when
exec() is not used for starting new processes, to ensure that different
processes still have different keys.

Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

kernel/sys.c: remove duplicated include

Link: http://lkml.kernel.org/r/20180821133424.18716-1-yuehaibing@huawei.com
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sys: don't hold uts_sem while accessing userspace memory

Holding uts_sem as a writer while accessing userspace memory allows a
namespace admin to stall all processes that attempt to take uts_sem.
Instead, move data through stack buffers and don't access userspace memory
while uts_sem is held.

Cc: stable@vger.kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

sysinfo: Remove get_monotonic_boottime()

get_monotonic_boottime() is deprecated because it uses the old 'timespec'
structure. This replaces one of the last callers with a call to
ktime_get_boottime.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: y2038@lists.linaro.org
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Link: https://lkml.kernel.org/r/20180618150114.849216-1-arnd@arndb.de

mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct

mmap_sem is on the hot path of kernel, and it very contended, but it is
abused too. It is used to protect arg_start|end and evn_start|end when
reading /proc/$PID/cmdline and /proc/$PID/environ, but it doesn't make
sense since those proc files just expect to read 4 values atomically and
not related to VM, they could be set to arbitrary values by C/R.

And, the mmap_sem contention may cause unexpected issue like below:

INFO: task ps:14018 blocked for more than 120 seconds.
Tainted: G E 4.9.79-009.ali3000.alios7.x86_64 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
message.
ps D 0 14018 1 0x00000004
Call Trace:
schedule+0x36/0x80
rwsem_down_read_failed+0xf0/0x150
call_rwsem_down_read_failed+0x18/0x30
down_read+0x20/0x40
proc_pid_cmdline_read+0xd9/0x4e0
__vfs_read+0x37/0x150
vfs_read+0x96/0x130
SyS_read+0x55/0xc0
entry_SYSCALL_64_fastpath+0x1a/0xc5

Both Alexey Dobriyan and Michal Hocko suggested to use dedicated lock
for them to mitigate the abuse of mmap_sem.

So, introduce a new spinlock in mm_struct to protect the concurrent
access to arg_start|end, env_start|end and others, as well as replace
write map_sem to read to protect the race condition between prctl and
sys_brk which might break check_data_rlimit(), and makes prctl more
friendly to other VM operations.

This patch just eliminates the abuse of mmap_sem, but it can't resolve
the above hung task warning completely since the later
access_remote_vm() call needs acquire mmap_sem. The mmap_sem
scalability issue will be solved in the future.

[yang.shi@linux.alibaba.com: add comment about mmap_sem and arg_lock]
Link: http://lkml.kernel.org/r/1524077799-80690-1-git-send-email-yang.shi@linux.alibaba.com
Link: http://lkml.kernel.org/r/1523730291-109696-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: fix potential Spectre v1 issue

`resource' can be controlled by user-space, hence leading to a potential
exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

kernel/sys.c:1474 __do_compat_sys_old_getrlimit() warn: potential spectre issue 'get_current()->signal->rlim' (local cap)
kernel/sys.c:1455 __do_sys_old_getrlimit() warn: potential spectre issue 'get_current()->signal->rlim' (local cap)

Fix this by sanitizing *resource* before using it to index
current->signal->rlim

Notice that given that speculation windows are large, the policy is to
kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Link: http://lkml.kernel.org/r/20180515030038.GA11822@embeddedor.com
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nospec: Allow getting/setting on non-current task

Adjust arch_prctl_get/set_spec_ctrl() to operate on tasks other than
current.

This is needed both for /proc/$pid/status queries and for seccomp (since
thread-syncing can trigger seccomp in non-current threads).

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

prctl: Add speculation control prctls

Add two new prctls to control aspects of speculation related vulnerabilites
and their mitigations to provide finer grained control over performance
impacting mitigations.

PR_GET_SPECULATION_CTRL returns the state of the speculation misfeature
which is selected with arg2 of prctl(2). The return value uses bit 0-2 with
the following meaning:

Bit Define Description
0 PR_SPEC_PRCTL Mitigation can be controlled per task by
PR_SET_SPECULATION_CTRL
1 PR_SPEC_ENABLE The speculation feature is enabled, mitigation is
disabled
2 PR_SPEC_DISABLE The speculation feature is disabled, mitigation is
enabled

If all bits are 0 the CPU is not affected by the speculation misfeature.

If PR_SPEC_PRCTL is set, then the per task control of the mitigation is
available. If not set, prctl(PR_SET_SPECULATION_CTRL) for the speculation
misfeature will fail.

PR_SET_SPECULATION_CTRL allows to control the speculation misfeature, which
is selected by arg2 of prctl(2) per task. arg3 is used to hand in the
control value, i.e. either PR_SPEC_ENABLE or PR_SPEC_DISABLE.

The common return values are:

EINVAL prctl is not implemented by the architecture or the unused prctl()
arguments are not 0
ENODEV arg2 is selecting a not supported speculation misfeature

PR_SET_SPECULATION_CTRL has these additional return values:

ERANGE arg3 is incorrect, i.e. it's not either PR_SPEC_ENABLE or PR_SPEC_DISABLE
ENXIO prctl control of the selected speculation misfeature is disabled

The first supported controlable speculation misfeature is
PR_SPEC_STORE_BYPASS. Add the define so this can be shared between
architectures.

Based on an initial patch from Tim Chen and mostly rewritten.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

kernel: add ksys_setsid() helper; remove in-kernel call to sys_setsid()

Using this helper allows us to avoid the in-kernel call to the
sys_setsid() syscall. The ksys_ prefix denotes that this function
is meant as a drop-in replacement for the syscall. In particular, it
uses the same calling convention as sys_setsid().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

kernel: provide ksys_*() wrappers for syscalls called by kernel/uid16.c

Using these helpers allows us to avoid the in-kernel calls to these
syscalls: sys_setregid(), sys_setgid(), sys_setreuid(), sys_setuid(),
sys_setresuid(), sys_setresgid(), sys_setfsuid(), and sys_setfsgid().

The ksys_ prefix denotes that these function are meant as a drop-in
replacement for the syscall. In particular, they use the same calling
convention.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

kernel: add do_getpgid() helper; remove internal call to sys_getpgid()

Using the do_getpgid() helper removes an in-kernel call to the
sys_getpgid() syscall.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

fix typo in assignment of fs default overflow gid

The patch remains without practical effect since both macros carry
identical values. Still, it might become a problem in the future if
(for whatever reason) the default overflow uid and gid differ. The
DEFAULT_FS_OVERFLOWGID macro was previously unused.

Signed-off-by: Wolffhardt Schwabe <wolffhardt.schwabe@fau.de>
Signed-off-by: Anatoliy Cherepantsev <anatoliy.cherepantsev@fau.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

arm64/sve: Add prctl controls for userspace vector length management

This patch adds two arm64-specific prctls, to permit userspace to
control its vector length:

* PR_SVE_SET_VL: set the thread's SVE vector length and vector
length inheritance mode.

* PR_SVE_GET_VL: get the same information.

Although these prctls resemble instruction set features in the SVE
architecture, they provide additional control: the vector length
inheritance mode is Linux-specific and nothing to do with the
architecture, and the architecture does not permit EL0 to set its
own vector length directly. Both can be used in portable tools
without requiring the use of SVE instructions.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alex Bennée <alex.bennee@linaro.org>
[will: Fixed up prctl constants to avoid clash with PDEATHSIG]
Signed-off-by: Will Deacon <will.deacon@arm.com>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

prctl: Allow local CAP_SYS_ADMIN changing exe_file

During checkpointing and restore of userspace tasks
we bumped into the situation, that it's not possible
to restore the tasks, which user namespace does not
have uid 0 or gid 0 mapped.

People create user namespace mappings like they want,
and there is no a limitation on obligatory uid and gid
"must be mapped". So, if there is no uid 0 or gid 0
in the mapping, it's impossible to restore mm->exe_file
of the processes belonging to this user namespace.

Also, there is no a workaround. It's impossible
to create a temporary uid/gid mapping, because
only one write to /proc/[pid]/uid_map and gid_map
is allowed during a namespace lifetime.
If there is an entry, then no more mapings can't be
written. If there isn't an entry, we can't write
there too, otherwise user task won't be able
to do that in the future.

The patch changes the check, and looks for CAP_SYS_ADMIN
instead of zero uid and gid. This allows to restore
a task independently of its user namespace mappings.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Serge Hallyn <serge@hallyn.com>
CC: "Eric W. Biederman" <ebiederm@xmission.com>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Michal Hocko <mhocko@suse.com>
CC: Andrei Vagin <avagin@openvz.org>
CC: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>
CC: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fix a braino in compat_sys_getrlimit()

Reported-and-tested-by: Meelis Roos <mroos@linux.ee>
Fixes: commit d9e968cb9f84 "getrlimit()/setrlimit(): move compat to native"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: make PR_SET_THP_DISABLE immediately active

PR_SET_THP_DISABLE has a rather subtle semantic. It doesn't affect any
existing mapping because it only updated mm->def_flags which is a
template for new mappings.

The mappings created after prctl(PR_SET_THP_DISABLE) have VM_NOHUGEPAGE
flag set. This can be quite surprising for all those applications which
do not do prctl(); fork() & exec() and want to control their own THP
behavior.

Another usecase when the immediate semantic of the prctl might be useful
is a combination of pre- and post-copy migration of containers with
CRIU. In this case CRIU populates a part of a memory region with data
that was saved during the pre-copy stage. Afterwards, the region is
registered with userfaultfd and CRIU expects to get page faults for the
parts of the region that were not yet populated. However, khugepaged
collapses the pages and the expected page faults do not occur.

In more general case, the prctl(PR_SET_THP_DISABLE) could be used as a
temporary mechanism for enabling/disabling THP process wide.

Implementation wise, a new MMF_DISABLE_THP flag is added. This flag is
tested when decision whether to use huge pages is taken either during
page fault of at the time of THP collapse.

It should be noted, that the new implementation makes PR_SET_THP_DISABLE
master override to any per-VMA setting, which was not the case
previously.

Fixes: a0715cc22601 ("mm, thp: add VM_INIT_DEF_MASK and PRCTL_THP_DISABLE")
Link: http://lkml.kernel.org/r/1496415802-30944-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

getrlimit()/setrlimit(): move compat to native

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

times(2): move compat to native

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

take compat_sys_old_getrlimit() to native syscall

... and sanitize the ifdefs in there

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

wait4(2)/waitid(2): separate copying rusage to userland

New helpers: kernel_waitid() and kernel_wait4(). sys_waitid(),
sys_wait4() and their compat variants switched to those. Copying
struct rusage to userland is left to syscall itself. For
compat_sys_wait4() that eliminates the use of set_fs() completely.
For compat_sys_waitid() it's still needed (for siginfo handling);
that will change shortly.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

rlimit: Properly call security_task_setrlimit

Modify do_prlimit to call security_task_setrlimit passing the task
whose rlimit we are changing not the tsk->group_leader.

In general this should not matter as the lsms implementing
security_task_setrlimit apparmor and selinux both examine the
task->cred to see what should be allowed on the destination task.

That task->cred is shared between tasks created with CLONE_THREAD
unless thread keyrings are in play, in which case both apparmor and
selinux create duplicate security contexts.

So the only time when it will matter which thread is passed to
security_task_setrlimit is if one of the threads of a process performs
an operation that changes only it's credentials. At which point if a
thread has done that we don't want to hide that information from the
lsms.

So fix the call of security_task_setrlimit. With the removal
of tsk->group_leader this makes the code slightly faster,
more comprehensible and maintainable.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

prlimit,security,selinux: add a security hook for prlimit

When SELinux was first added to the kernel, a process could only get
and set its own resource limits via getrlimit(2) and setrlimit(2), so no
MAC checks were required for those operations, and thus no security hooks
were defined for them. Later, SELinux introduced a hook for setlimit(2)
with a check if the hard limit was being changed in order to be able to
rely on the hard limit value as a safe reset point upon context
transitions.

Later on, when prlimit(2) was added to the kernel with the ability to get
or set resource limits (hard or soft) of another process, LSM/SELinux was
not updated other than to pass the target process to the setrlimit hook.
This resulted in incomplete control over both getting and setting the
resource limits of another process.

Add a new security_task_prlimit() hook to the check_prlimit_permission()
function to provide complete mediation. The hook is only called when
acting on another task, and only if the existing DAC/capability checks
would allow access. Pass flags down to the hook to indicate whether the
prlimit(2) call will read, write, or both read and write the resource
limits of the target process.

The existing security_task_setrlimit() hook is left alone; it continues
to serve a purpose in supporting the ability to make decisions based on
the old and/or new resource limit values when setting limits. This
is consistent with the DAC/capability logic, where
check_prlimit_permission() performs generic DAC/capability checks for
acting on another task, while do_prlimit() performs a capability check
based on a comparison of the old and new resource limits. Fix the
inline documentation for the hook to match the code.

Implement the new hook for SELinux. For setting resource limits, we
reuse the existing setrlimit permission. Note that this does overload
the setrlimit permission to mean the ability to set the resource limit
(soft or hard) of another process or the ability to change one's own
hard limit. For getting resource limits, a new getrlimit permission
is defined. This was not originally defined since getrlimit(2) could
only be used to obtain a process' own limits.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <james.l.morris@oracle.com>

sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>

Introduce a trivial, mostly empty <linux/sched/cputime.h> header
to prepare for the moving of cputime functionality out of sched.h.

Update all code that relies on these facilities.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>

We are going to split <linux/sched/task.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/task.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/stat.h>

We are going to split <linux/sched/stat.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/stat.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/coredump.h>

We are going to split <linux/sched/coredump.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/coredump.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/mm.h>

We are going to split <linux/sched/mm.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/mm.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

The APIs that are going to be moved first are:

mm_alloc()
__mmdrop()
mmdrop()
mmdrop_async_fn()
mmdrop_async()
mmget_not_zero()
mmput()
mmput_async()
get_task_mm()
mm_access()
mm_release()

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/autogroup.h>

We are going to split <linux/sched/autogroup.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/autogroup.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/loadavg.h>

We are going to split <linux/sched/loadavg.h> out of <linux/sched.h>, which
will have to be picked up from a couple of .c files.

Create a trivial placeholder <linux/sched/topology.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

prctl: propagate has_child_subreaper flag to every descendant

If process forks some children when it has is_child_subreaper
flag enabled they will inherit has_child_subreaper flag - first
group, when is_child_subreaper is disabled forked children will
not inherit it - second group. So child-subreaper does not reparent
all his descendants when their parents die. Having these two
differently behaving groups can lead to confusion. Also it is
a problem for CRIU, as when we restore process tree we need to
somehow determine which descendants belong to which group and
much harder - to put them exactly to these group.

To simplify these we can add a propagation of has_child_subreaper
flag on PR_SET_CHILD_SUBREAPER, walking all descendants of child-
subreaper to setup has_child_subreaper flag.

In common cases when process like systemd first sets itself to
be a child-subreaper and only after that forks its services, we will
have zero-length list of descendants to walk. Testing with binary
subtree of 2^15 processes prctl took < 0.007 sec and has shown close
to linear dependency(~0.2 * n * usec) on lower numbers of processes.

Moreover, I doubt someone intentionaly pre-forks the children whitch
should reparent to init before becoming subreaper, because some our
ancestor migh have had is_child_subreaper flag while forking our
sub-tree and our childs will all inherit has_child_subreaper flag,
and we have no way to influence it. And only way to check if we have
no has_child_subreaper flag is to create some childs, kill them and
see where they will reparent to.

Using walk_process_tree helper to walk subtree, thanks to Oleg! Timing
seems to be the same.

Optimize:

a) When descendant already has has_child_subreaper flag all his subtree
has it too already.

* for a) to be true need to move has_child_subreaper inheritance under
the same tasklist_lock with adding task to its ->real_parent->children
as without it process can inherit zero has_child_subreaper, then we
set 1 to it's parent flag, check that parent has no more children, and
only after child with wrong flag is added to the tree.

* Also make these inheritance more clear by using real_parent instead of
current, as on clone(CLONE_PARENT) if current has is_child_subreaper
and real_parent has no is_child_subreaper or has_child_subreaper, child
will have has_child_subreaper flag set without actually having a
subreaper in it's ancestors.

b) When some descendant is child_reaper, it's subtree is in different
pidns from us(original child-subreaper) and processes from other pidns
will never reparent to us.

So we can skip their(a,b) subtree from walk.

v2: switch to walk_process_tree() general helper, move
has_child_subreaper inheritance
v3: remove csr_descendant leftover, change current to real_parent
in has_child_subreaper inheritance
v4: small commit message fix

Fixes: ebec18a6d3aa ("prctl: add PR_{SET,GET}_CHILD_SUBREAPER to allow simple process supervision")
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

sched/cputime: Convert task/group cputime to nsecs

Now that most cputime readers use the transition API which return the
task cputime in old style cputime_t, we can safely store the cputime in
nsecs. This will eventually make cputime statistics less opaque and more
granular. Back and forth convertions between cputime_t and nsecs in order
to deal with cputime_t random granularity won't be needed anymore.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-8-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Replace <asm/uaccess.h> with <linux/uaccess.h> globally

This was entirely automated, using the script by Al:

PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl: remove one-shot limitation for changing exe link

This limitation came with the reason to remove "another way for
malicious code to obscure a compromised program and masquerade as a
benign process" by allowing "security-concious program can use this
prctl once during its early initialization to ensure the prctl cannot
later be abused for this purpose":

http://marc.info/?l=linux-kernel&m=133160684517468&w=2

This explanation doesn't look sufficient. The only thing "exe" link is
indicating is the file, used to execve, which is basically nothing and
not reliable immediately after process has returned from execve system
call.

Moreover, to use this feture, all the mappings to previous exe file have
to be unmapped and all the new exe file permissions must be satisfied.

Which means, that changing exe link is very similar to calling execve on
the binary.

The need to remove this limitations comes from migration of NFS mount
point, which is not accessible during restore and replaced by other file
system. Because of this exe link has to be changed twice.

[akpm@linux-foundation.org: fix up comment]
Link: http://lkml.kernel.org/r/20160927153755.9337.69650.stgit@localhost.localdomain
Signed-off-by: Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

posix-timers: Make them configurable

Some embedded systems have no use for them. This removes about
25KB from the kernel binary size when configured out.

Corresponding syscalls are routed to a stub logging the attempt to
use those syscalls which should be enough of a clue if they were
disabled without proper consideration. They are: timer_create,
timer_gettime: timer_getoverrun, timer_settime, timer_delete,
clock_adjtime, setitimer, getitimer, alarm.

The clock_settime, clock_gettime, clock_getres and clock_nanosleep
syscalls are replaced by simple wrappers compatible with CLOCK_REALTIME,
CLOCK_MONOTONIC and CLOCK_BOOTTIME only which should cover the vast
majority of use cases with very little code.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: linux-kbuild@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Michal Marek <mmarek@suse.com>
Cc: Edward Cree <ecree@solarflare.com>
Link: http://lkml.kernel.org/r/1478841010-28605-7-git-send-email-nicolas.pitre@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

prctl: make PR_SET_THP_DISABLE wait for mmap_sem killable

PR_SET_THP_DISABLE requires mmap_sem for write. If the waiting task
gets killed by the oom killer it would block oom_reaper from
asynchronous address space reclaim and reduce the chances of timely OOM
resolving. Wait for the lock in the killable mode and return with EINTR
if the task got killed while waiting.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Alex Thorlton <athorlton@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

timer: convert timer_slack_ns from unsigned long to u64

This patchset introduces a /proc/<pid>/timerslack_ns interface which
would allow controlling processes to be able to set the timerslack value
on other processes in order to save power by avoiding wakeups (Something
Android currently does via out-of-tree patches).

The first patch tries to fix the internal timer_slack_ns usage which was
defined as a long, which limits the slack range to ~4 seconds on 32bit
systems. It converts it to a u64, which provides the same basically
unlimited slack (500 years) on both 32bit and 64bit machines.

The second patch introduces the /proc/<pid>/timerslack_ns interface
which allows the full 64bit slack range for a task to be read or set on
both 32bit and 64bit machines.

With these two patches, on a 32bit machine, after setting the slack on
bash to 10 seconds:

$ time sleep 1

real 0m10.747s
user 0m0.001s
sys 0m0.005s

The first patch is a little ugly, since I had to chase the slack delta
arguments through a number of functions converting them to u64s. Let me
know if it makes sense to break that up more or not.

Other than that things are fairly straightforward.

This patch (of 2):

The timer_slack_ns value in the task struct is currently a unsigned
long. This means that on 32bit applications, the maximum slack is just
over 4 seconds. However, on 64bit machines, its much much larger (~500
years).

This disparity could make application development a little (as well as
the default_slack) to a u64. This means both 32bit and 64bit systems
have the same effective internal slack range.

Now the existing ABI via PR_GET_TIMERSLACK and PR_SET_TIMERSLACK specify
the interface as a unsigned long, so we preserve that limitation on
32bit systems, where SET_TIMERSLACK can only set the slack to a unsigned
long value, and GET_TIMERSLACK will return ULONG_MAX if the slack is
actually larger then what can be stored by an unsigned long.

This patch also modifies hrtimer functions which specified the slack
delta as a unsigned long.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oren Laadan <orenl@cellrox.com>
Cc: Ruchi Kandoi <kandoiruchi@google.com>
Cc: Rom Lemarchand <romlem@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl: take mmap sem for writing to protect against others

An unprivileged user can trigger an oops on a kernel with
CONFIG_CHECKPOINT_RESTORE.

proc_pid_cmdline_read takes mmap_sem for reading and obtains args + env
start/end values. These get sanity checked as follows:
BUG_ON(arg_start > arg_end);
BUG_ON(env_start > env_end);

These can be changed by prctl_set_mm. Turns out also takes the semaphore for
reading, effectively rendering it useless. This results in:

kernel BUG at fs/proc/base.c:240!
invalid opcode: 0000 [#1] SMP
Modules linked in: virtio_net
CPU: 0 PID: 925 Comm: a.out Not tainted 4.4.0-rc8-next-20160105dupa+ #71
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
task: ffff880077a68000 ti: ffff8800784d0000 task.ti: ffff8800784d0000
RIP: proc_pid_cmdline_read+0x520/0x530
RSP: 0018:ffff8800784d3db8 EFLAGS: 00010206
RAX: ffff880077c5b6b0 RBX: ffff8800784d3f18 RCX: 0000000000000000
RDX: 0000000000000002 RSI: 00007f78e8857000 RDI: 0000000000000246
RBP: ffff8800784d3e40 R08: 0000000000000008 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000050
R13: 00007f78e8857800 R14: ffff88006fcef000 R15: ffff880077c5b600
FS: 00007f78e884a740(0000) GS:ffff88007b200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007f78e8361770 CR3: 00000000790a5000 CR4: 00000000000006f0
Call Trace:
__vfs_read+0x37/0x100
vfs_read+0x82/0x130
SyS_read+0x58/0xd0
entry_SYSCALL_64_fastpath+0x12/0x76
Code: 4c 8b 7d a8 eb e9 48 8b 9d 78 ff ff ff 4c 8b 7d 90 48 8b 03 48 39 45 a8 0f 87 f0 fe ff ff e9 d1 fe ff ff 4c 8b 7d 90 eb c6 0f 0b <0f> 0b 0f 0b 66 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00
RIP proc_pid_cmdline_read+0x520/0x530
---[ end trace 97882617ae9c6818 ]---

Turns out there are instances where the code just reads aformentioned
values without locking whatsoever - namely environ_read and get_cmdline.

Interestingly these functions look quite resilient against bogus values,
but I don't believe this should be relied upon.

The first patch gets rid of the oops bug by grabbing mmap_sem for
writing.

The second patch is optional and puts locking around aformentioned
consumers for safety. Consumers of other fields don't seem to benefit
from similar treatment and are left untouched.

This patch (of 2):

The code was taking the semaphore for reading, which does not protect
against readers nor concurrent modifications.

The problem could cause a sanity checks to fail in procfs's cmdline
reader, resulting in an OOPS.

Note that some functions perform an unlocked read of various mm fields,
but they seem to be fine despite possible modificaton.

Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jarod Wilson <jarod@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anshuman Khandual <anshuman.linux@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode

setpriority(PRIO_USER, 0, x) will change the priority of tasks outside of
the current pid namespace. This is in contrast to both the other modes of
setpriority and the example of kill(-1). Fix this. getpriority and
ioprio have the same failure mode, fix them too.

Eric said:

: After some more thinking about it this patch sounds justifiable.
:
: My goal with namespaces is not to build perfect isolation mechanisms
: as that can get into ill defined territory, but to build well defined
: mechanisms. And to handle the corner cases so you can use only
: a single namespace with well defined results.
:
: In this case you have found the two interfaces I am aware of that
: identify processes by uid instead of by pid. Which quite frankly is
: weird. Unfortunately the weird unexpected cases are hard to handle
: in the usual way.
:
: I was hoping for a little more information. Changes like this one we
: have to be careful of because someone might be depending on the current
: behavior. I don't think they are and I do think this make sense as part
: of the pid namespace.

Signed-off-by: Ben Segall <bsegall@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ambrose Feinstein <ambrose@google.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

vfs: Commit to never having exectuables on proc and sysfs.

Today proc and sysfs do not contain any executable files. Several
applications today mount proc or sysfs without noexec and nosuid and
then depend on there being no exectuables files on proc or sysfs.
Having any executable files show on proc or sysfs would cause
a user space visible regression, and most likely security problems.

Therefore commit to never allowing executables on proc and sysfs by
adding a new flag to mark them as filesystems without executables and
enforce that flag.

Test the flag where MNT_NOEXEC is tested today, so that the only user
visible effect will be that exectuables will be treated as if the
execute bit is cleared.

The filesystems proc and sysfs do not currently incoporate any
executable files so this does not result in any user visible effects.

This makes it unnecessary to vet changes to proc and sysfs tightly for
adding exectuable files or changes to chattr that would modify
existing files, as no matter what the individual file say they will
not be treated as exectuable files by the vfs.

Not having to vet changes to closely is important as without this we
are only one proc_create call (or another goof up in the
implementation of notify_change) from having problematic executables
on proc. Those mistakes are all too easy to make and would create
a situation where there are security issues or the assumptions of
some program having to be broken (and cause userspace regressions).

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

prctl: more prctl(PR_SET_MM_*) checks

Individual prctl(PR_SET_MM_*) calls do some checking to maintain a
consistent view of mm->arg_start et al fields, but not enough. In
particular PR_SET_MM_ARG_START/PR_SET_MM_ARG_END/ R_SET_MM_ENV_START/
PR_SET_MM_ENV_END only check that the address lies in an existing VMA,
but don't check that the start address is lower than the end address _at
all_.

Consolidate all consistency checks, so there will be no difference in
the future between PR_SET_MM_MAP and individual PR_SET_MM_* calls.

The program below makes both ARGV and ENVP areas be reversed. It makes
/proc/$PID/cmdline show garbage (it doesn't oops by luck).

#include <sys/mman.h>
#include <sys/prctl.h>
#include <unistd.h>

enum {PAGE_SIZE=4096};

int main(void)
{
void *p;

p = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);

#define PR_SET_MM 35
#define PR_SET_MM_ARG_START 8
#define PR_SET_MM_ARG_END 9
#define PR_SET_MM_ENV_START 10
#define PR_SET_MM_ENV_END 11
prctl(PR_SET_MM, PR_SET_MM_ARG_START, (unsigned long)p + PAGE_SIZE - 1, 0, 0);
prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long)p, 0, 0);
prctl(PR_SET_MM, PR_SET_MM_ENV_START, (unsigned long)p + PAGE_SIZE - 1, 0, 0);
prctl(PR_SET_MM, PR_SET_MM_ENV_END, (unsigned long)p, 0, 0);

pause();
return 0;
}

[akpm@linux-foundation.org: tidy code, tweak comment]
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jarod Wilson <jarod@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

x86/mpx: Clean up the code by not passing a task pointer around when unnecessary

The MPX code can only work on the current task. You can not,
for instance, enable MPX management in another process or
thread. You can also not handle a fault for another process or
thread.

Despite this, we pass a task_struct around prolifically. This
patch removes all of the task struct passing for code paths
where the code can not deal with another task (which turns out
to be all of them).

This has no functional changes. It's just a cleanup.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183702.6A81DA2C@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

prctl: avoid using mmap_sem for exe_file serialization

Oleg cleverly suggested using xchg() to set the new mm->exe_file instead
of calling set_mm_exe_file() which requires some form of serialization --
mmap_sem in this case. For archs that do not have atomic rmw instructions
we still fallback to a spinlock alternative, so this should always be
safe. As such, we only need the mmap_sem for looking up the backing
vm_file, which can be done sharing the lock. Naturally, this means we
need to manually deal with both the new and old file reference counting,
and we need not worry about the MMF_EXE_FILE_CHANGED bits, which can
probably be deleted in the future anyway.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel: conditionally support non-root users, groups and capabilities

There are a lot of embedded systems that run most or all of their
functionality in init, running as root:root. For these systems,
supporting multiple users is not necessary.

This patch adds a new symbol, CONFIG_MULTIUSER, that makes support for
non-root users, non-root groups, and capabilities optional. It is enabled
under CONFIG_EXPERT menu.

When this symbol is not defined, UID and GID are zero in any possible case
and processes always have all capabilities.

The following syscalls are compiled out: setuid, setregid, setgid,
setreuid, setresuid, getresuid, setresgid, getresgid, setgroups,
getgroups, setfsuid, setfsgid, capget, capset.

Also, groups.c is compiled out completely.

In kernel/capability.c, capable function was moved in order to avoid
adding two ifdef blocks.

This change saves about 25 KB on a defconfig build. The most minimal
kernels have total text sizes in the high hundreds of kB rather than
low MB. (The 25k goes down a bit with allnoconfig, but not that much.

The kernel was booted in Qemu. All the common functionalities work.
Adding users/groups is not possible, failing with -ENOSYS.

Bloat-o-meter output:
add/remove: 7/87 grow/shrink: 19/397 up/down: 1675/-26325 (-24650)

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Iulia Manda <iulia.manda21@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: fix UNAME26 for 4.0

There's a uname workaround for broken userspace which can't handle kernel
versions of 3.x. Update it for 4.x.

Signed-off-by: Jon DeVree <nuxi@vault24.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MIPS,prctl: add PR_[GS]ET_FP_MODE prctl options for MIPS

Userland code may be built using an ABI which permits linking to objects
that have more restrictive floating point requirements. For example,
userland code may be built to target the O32 FPXX ABI. Such code may be
linked with other FPXX code, or code built for either one of the more
restrictive FP32 or FP64. When linking with more restrictive code, the
overall requirement of the process becomes that of the more restrictive
code. The kernel has no way to know in advance which mode the process
will need to be executed in, and indeed it may need to change during
execution. The dynamic loader is the only code which will know the
overall required mode, and so it needs to have a means to instruct the
kernel to switch the FP mode of the process.

This patch introduces 2 new options to the prctl syscall which provide
such a capability. The FP mode of the process is represented as a
simple bitmask combining a number of mode bits mirroring those present
in the hardware. Userland can either retrieve the current FP mode of
the process:

mode = prctl(PR_GET_FP_MODE);

or modify the current FP mode of the process:

err = prctl(PR_SET_FP_MODE, new_mode);

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8899/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

x86, mpx: Strictly enforce empty prctl() args

Description from Michael Kerrisk. He suggested an identical patch
to one I had already coded up and tested.

commit fe3d197f8431 "x86, mpx: On-demand kernel allocation of bounds
tables" added two new prctl() operations, PR_MPX_ENABLE_MANAGEMENT and
PR_MPX_DISABLE_MANAGEMENT. However, no checks were included to ensure
that unused arguments are zero, as is done in many existing prctl()s
and as should be done for all new prctl()s. This patch adds the
required checks.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Suggested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20150108223022.7F56FD13@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

x86, mpx: On-demand kernel allocation of bounds tables

This is really the meat of the MPX patch set. If there is one patch to
review in the entire series, this is the one. There is a new ABI here
and this kernel code also interacts with userspace memory in a
relatively unusual manner. (small FAQ below).

Long Description:

This patch adds two prctl() commands to provide enable or disable the
management of bounds tables in kernel, including on-demand kernel
allocation (See the patch "on-demand kernel allocation of bounds tables")
and cleanup (See the patch "cleanup unused bound tables"). Applications
do not strictly need the kernel to manage bounds tables and we expect
some applications to use MPX without taking advantage of this kernel
support. This means the kernel can not simply infer whether an application
needs bounds table management from the MPX registers. The prctl() is an
explicit signal from userspace.

PR_MPX_ENABLE_MANAGEMENT is meant to be a signal from userspace to
require kernel's help in managing bounds tables.

PR_MPX_DISABLE_MANAGEMENT is the opposite, meaning that userspace don't
want kernel's help any more. With PR_MPX_DISABLE_MANAGEMENT, the kernel
won't allocate and free bounds tables even if the CPU supports MPX.

PR_MPX_ENABLE_MANAGEMENT will fetch the base address of the bounds
directory out of a userspace register (bndcfgu) and then cache it into
a new field (->bd_addr) in the 'mm_struct'. PR_MPX_DISABLE_MANAGEMENT
will set "bd_addr" to an invalid address. Using this scheme, we can
use "bd_addr" to determine whether the management of bounds tables in
kernel is enabled.

Also, the only way to access that bndcfgu register is via an xsaves,
which can be expensive. Caching "bd_addr" like this also helps reduce
the cost of those xsaves when doing table cleanup at munmap() time.
Unfortunately, we can not apply this optimization to #BR fault time
because we need an xsave to get the value of BNDSTATUS.

==== Why does the hardware even have these Bounds Tables? ====

MPX only has 4 hardware registers for storing bounds information.
If MPX-enabled code needs more than these 4 registers, it needs to
spill them somewhere. It has two special instructions for this
which allow the bounds to be moved between the bounds registers
and some new "bounds tables".

They are similar conceptually to a page fault and will be raised by
the MPX hardware during both bounds violations or when the tables
are not present. This patch handles those #BR exceptions for
not-present tables by carving the space out of the normal processes
address space (essentially calling the new mmap() interface indroduced
earlier in this patch set.) and then pointing the bounds-directory
over to it.

The tables *need* to be accessed and controlled by userspace because
the instructions for moving bounds in and out of them are extremely
frequent. They potentially happen every time a register pointing to
memory is dereferenced. Any direct kernel involvement (like a syscall)
to access the tables would obviously destroy performance.

==== Why not do this in userspace? ====

This patch is obviously doing this allocation in the kernel.
However, MPX does not strictly *require* anything in the kernel.
It can theoretically be done completely from userspace. Here are
a few ways this *could* be done. I don't think any of them are
practical in the real-world, but here they are.

Q: Can virtual space simply be reserved for the bounds tables so
that we never have to allocate them?
A: As noted earlier, these tables are *HUGE*. An X-GB virtual
area needs 4*X GB of virtual space, plus 2GB for the bounds
directory. If we were to preallocate them for the 128TB of
user virtual address space, we would need to reserve 512TB+2GB,
which is larger than the entire virtual address space today.
This means they can not be reserved ahead of time. Also, a
single process's pre-popualated bounds directory consumes 2GB
of virtual *AND* physical memory. IOW, it's completely
infeasible to prepopulate bounds directories.

Q: Can we preallocate bounds table space at the same time memory
is allocated which might contain pointers that might eventually
need bounds tables?
A: This would work if we could hook the site of each and every
memory allocation syscall. This can be done for small,
constrained applications. But, it isn't practical at a larger
scale since a given app has no way of controlling how all the
parts of the app might allocate memory (think libraries). The
kernel is really the only place to intercept these calls.

Q: Could a bounds fault be handed to userspace and the tables
allocated there in a signal handler instead of in the kernel?
A: (thanks to tglx) mmap() is not on the list of safe async
handler functions and even if mmap() would work it still
requires locking or nasty tricks to keep track of the
allocation state there.

Having ruled out all of the userspace-only approaches for managing
bounds tables that we could think of, we create them on demand in
the kernel.

Based-on-patch-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151829.AD4310DE@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/sys.c: compat sysinfo syscall: fix undefined behavior

Fix undefined behavior and compiler warning by replacing right shift 32
with upper_32_bits macro

Signed-off-by: Scotty Bauer <sbauer@eng.utah.edu>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: whitespace fixes

Fix minor errors and warning messages in kernel/sys.c. These errors were
reported by checkpatch while working with some modifications in sys.c
file. Fixing this first will help me to improve my further patches.

ERROR: trailing whitespace - 9
ERROR: do not use assignment in if condition - 4
ERROR: spaces required around that '?' (ctx:VxO) - 10
ERROR: switch and case should be at the same indent - 3

total 26 errors & 3 warnings fixed.

Signed-off-by: vishnu.ps <vishnu.ps@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: use VM_BUG_ON_MM where possible

Dump the contents of the relevant struct_mm when we hit the bug condition.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl: PR_SET_MM -- introduce PR_SET_MM_MAP operation

During development of c/r we've noticed that in case if we need to support
user namespaces we face a problem with capabilities in prctl(PR_SET_MM,
...) call, in particular once new user namespace is created
capable(CAP_SYS_RESOURCE) no longer passes.

A approach is to eliminate CAP_SYS_RESOURCE check but pass all new values
in one bundle, which would allow the kernel to make more intensive test
for sanity of values and same time allow us to support checkpoint/restore
of user namespaces.

Thus a new command PR_SET_MM_MAP introduced. It takes a pointer of
prctl_mm_map structure which carries all the members to be updated.

prctl(PR_SET_MM, PR_SET_MM_MAP, struct prctl_mm_map *, size)

struct prctl_mm_map {
__u64 start_code;
__u64 end_code;
__u64 start_data;
__u64 end_data;
__u64 start_brk;
__u64 brk;
__u64 start_stack;
__u64 arg_start;
__u64 arg_end;
__u64 env_start;
__u64 env_end;
__u64 *auxv;
__u32 auxv_size;
__u32 exe_fd;
};

All members except @exe_fd correspond ones of struct mm_struct. To figure
out which available values these members may take here are meanings of the
members.

- start_code, end_code: represent bounds of executable code area
- start_data, end_data: represent bounds of data area
- start_brk, brk: used to calculate bounds for brk() syscall
- start_stack: used when accounting space needed for command
line arguments, environment and shmat() syscall
- arg_start, arg_end, env_start, env_end: represent memory area
supplied for command line arguments and environment variables
- auxv, auxv_size: carries auxiliary vector, Elf format specifics
- exe_fd: file descriptor number for executable link (/proc/self/exe)

Thus we apply the following requirements to the values

1) Any member except @auxv, @auxv_size, @exe_fd is rather an address
in user space thus it must be laying inside [mmap_min_addr, mmap_max_addr)
interval.

2) While @[start|end]_code and @[start|end]_data may point to an nonexisting
VMAs (say a program maps own new .text and .data segments during execution)
the rest of members should belong to VMA which must exist.

3) Addresses must be ordered, ie @start_ member must not be greater or
equal to appropriate @end_ member.

4) As in regular Elf loading procedure we require that @start_brk and
@brk be greater than @end_data.

5) If RLIMIT_DATA rlimit is set to non-infinity new values should not
exceed existing limit. Same applies to RLIMIT_STACK.

6) Auxiliary vector size must not exceed existing one (which is
predefined as AT_VECTOR_SIZE and depends on architecture).

7) File descriptor passed in @exe_file should be pointing
to executable file (because we use existing prctl_set_mm_exe_file_locked
helper it ensures that the file we are going to use as exe link has all
required permission granted).

Now about where these members are involved inside kernel code:

- @start_code and @end_code are used in /proc/$pid/[stat|statm] output;

- @start_data and @end_data are used in /proc/$pid/[stat|statm] output,
also they are considered if there enough space for brk() syscall
result if RLIMIT_DATA is set;

- @start_brk shown in /proc/$pid/stat output and accounted in brk()
syscall if RLIMIT_DATA is set; also this member is tested to
find a symbolic name of mmap event for perf system (we choose
if event is generated for "heap" area); one more aplication is
selinux -- we test if a process has PROCESS__EXECHEAP permission
if trying to make heap area being executable with mprotect() syscall;

- @brk is a current value for brk() syscall which lays inside heap
area, it's shown in /proc/$pid/stat. When syscall brk() succesfully
provides new memory area to a user space upon brk() completion the
mm::brk is updated to carry new value;

Both @start_brk and @brk are actively used in /proc/$pid/maps
and /proc/$pid/smaps output to find a symbolic name "heap" for
VMA being scanned;

- @start_stack is printed out in /proc/$pid/stat and used to
find a symbolic name "stack" for task and threads in
/proc/$pid/maps and /proc/$pid/smaps output, and as the same
as with @start_brk -- perf system uses it for event naming.
Also kernel treat this member as a start address of where
to map vDSO pages and to check if there is enough space
for shmat() syscall;

- @arg_start, @arg_end, @env_start and @env_end are printed out
in /proc/$pid/stat. Another access to the data these members
represent is to read /proc/$pid/environ or /proc/$pid/cmdline.
Any attempt to read these areas kernel tests with access_process_vm
helper so a user must have enough rights for this action;

- @auxv and @auxv_size may be read from /proc/$pid/auxv. Strictly
speaking kernel doesn't care much about which exactly data is
sitting there because it is solely for userspace;

- @exe_fd is referred from /proc/$pid/exe and when generating
coredump. We uses prctl_set_mm_exe_file_locked helper to update
this member, so exe-file link modification remains one-shot
action.

Still note that updating exe-file link now doesn't require sys-resource
capability anymore, after all there is no much profit in preventing setup
own file link (there are a number of ways to execute own code -- ptrace,
ld-preload, so that the only reliable way to find which exactly code is
executed is to inspect running program memory). Still we require the
caller to be at least user-namespace root user.

I believe the old interface should be deprecated and ripped off in a
couple of kernel releases if no one against.

To test if new interface is implemented in the kernel one can pass
PR_SET_MM_MAP_SIZE opcode and the kernel returns the size of currently
supported struct prctl_mm_map.

[akpm@linux-foundation.org: fix 80-col wordwrap in macro definitions]
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Andrew Vagin <avagin@openvz.org>
Tested-by: Andrew Vagin <avagin@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Julien Tinnes <jln@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl: PR_SET_MM -- factor out mmap_sem when updating mm::exe_file

Instead of taking mm->mmap_sem inside prctl_set_mm_exe_file() move it out
and rename the helper to prctl_set_mm_exe_file_locked(). This will allow
to reuse this function in a next patch.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Julien Tinnes <jln@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: use may_adjust_brk helper

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Julien Tinnes <jln@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

time, signal: Protect resource use statistics with seqlock

Both times() and clock_gettime(CLOCK_PROCESS_CPUTIME_ID) have scalability
issues on large systems, due to both functions being serialized with a
lock.

The lock protects against reporting a wrong value, due to a thread in the
task group exiting, its statistics reporting up to the signal struct, and
that exited task's statistics being counted twice (or not at all).

Protecting that with a lock results in times() and clock_gettime() being
completely serialized on large systems.

This can be fixed by using a seqlock around the events that gather and
propagate statistics. As an additional benefit, the protection code can
be moved into thread_group_cputime(), slightly simplifying the calling
functions.

In the case of posix_cpu_clock_get_task() things can be simplified a
lot, because the calling function already ensures that the task sticks
around, and the rest is now taken care of in thread_group_cputime().

This way the statistics reporting code can run lockless.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Daeseok Youn <daeseok.youn@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guillaume Morin <guillaume@morinfr.org>
Cc: Ionut Alexa <ionut.m.alexa@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Michal Schmidt <mschmidt@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: umgwanakikbuti@gmail.com
Cc: fweisbec@gmail.com
Cc: srao@redhat.com
Cc: lwoodman@redhat.com
Cc: atheurer@redhat.com
Link: http://lkml.kernel.org/r/20140816134010.26a9b572@annuminas.surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched: move no_new_privs into new atomic flags

Since seccomp transitions between threads requires updates to the
no_new_privs flag to be atomic, the flag must be part of an atomic flag
set. This moves the nnp flag into a separate task field, and introduces
accessors.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

sched: Consolidate open coded implementations of nice level frobbing into nice_to_rlimit() and rlimit_to_nice()

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/a568a1e3cc8e78648f41b5035fa5e381d36274da.1399532322.git.yangds.fnst@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

mm, thp: add VM_INIT_DEF_MASK and PRCTL_THP_DISABLE

Add VM_INIT_DEF_MASK, to allow us to set the default flags for VMs. It
also adds a prctl control which allows us to set the THP disable bit in
mm->def_flags so that VMs will pick up the setting as they are created.

Signed-off-by: Alex Thorlton <athorlton@sgi.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sys: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/0261f094b836f1acbcdf52e7166487c0c77323c8.1392103744.git.yangds.fnst@cn.fujitsu.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sys.c: k_getrusage() can use while_each_thread()

Change k_getrusage() to use while_each_thread(), no changes in the
compiled code.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Sameer Nanda <snanda@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

exec: kill task_struct->did_exec

We can kill either task->did_exec or PF_FORKNOEXEC, they are mutually
exclusive. The patch kills ->did_exec because it has a single user.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: remove obsolete #include <linux/kexec.h>

Commit 15d94b82565e ("reboot: move shutdown/reboot related functions to
kernel/reboot.c") moved all kexec-related functionality to
kernel/reboot.c, so kernel/sys.c no longer needs to include
<linux/kexec.h>.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Robin Holt <holt@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

userns: Kill nsown_capable it makes the wrong thing easy

nsown_capable is a special case of ns_capable essentially for just CAP_SETUID and
CAP_SETGID. For the existing users it doesn't noticably simplify things and
from the suggested patches I have seen it encourages people to do the wrong
thing. So remove nsown_capable.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

reboot: move shutdown/reboot related functions to kernel/reboot.c

This patch is preparatory. It moves reboot related syscall, etc
functions from kernel/sys.c to kernel/reboot.c.

Signed-off-by: Robin Holt <holt@sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

reboot: remove -stable friendly PF_THREAD_BOUND define

Remove the prior patch's #define for easier backporting to the stable
releases.

Signed-off-by: Robin Holt <holt@sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

exit.c: unexport __set_special_pids()

Move __set_special_pids() from exit.c to sys.c close to its single caller
and make it static.

And rename it to set_special_pids(), another helper with this name has
gone away.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c:do_sysinfo(): use get_monotonic_boottime()

Change do_sysinfo() to use get_monotonic_boottime() instead of
do_posix_clock_monotonic_gettime() + monotonic_to_bootbased().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Tomas Janousek <tjanouse@redhat.com>
Cc: Tomas Smetana <tsmetana@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: sys_reboot(): fix malformed panic message

If LINUX_REBOOT_CMD_HALT for reboot failed, the message "cannot halt" will
stay on the same line with the next message, so append a '\n'.

Signed-off-by: liguang <lig.fnst@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

reboot: rigrate shutdown/reboot to boot cpu

We recently noticed that reboot of a 1024 cpu machine takes approx 16
minutes of just stopping the cpus. The slowdown was tracked to commit
f96972f2dc63 ("kernel/sys.c: call disable_nonboot_cpus() in
kernel_restart()").

The current implementation does all the work of hot removing the cpus
before halting the system. We are switching to just migrating to the
boot cpu and then continuing with shutdown/reboot.

This also has the effect of not breaking x86's command line parameter
for specifying the reboot cpu. Note, this code was shamelessly copied
from arch/x86/kernel/reboot.c with bits removed pertaining to the
reboot_cpu command line parameter.

Signed-off-by: Robin Holt <holt@sgi.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: make prctl(PR_SET_MM) generally available

The purpose of this patch is to allow privileged processes to set
their own per-memory memory-region fields:

start_code, end_code, start_data, end_data, start_brk, brk,
start_stack, arg_start, arg_end, env_start, env_end.

This functionality is needed by any application or package that needs to
reconstruct Linux processes, that is, to start them in any way other than
by means of an "execve()" from an executable file. This includes:

1. Restoring processes from a checkpoint-file (by all potential
user-level checkpointing packages, not only CRIU's).
2. Restarting processes on another node after process migration.
3. Starting duplicated copies of a running process (for reliability
and high-availablity).
4. Starting a process from an executable format that is not supported
by Linux, thus requiring a "manual execve" by a user-level utility.
5. Similarly, starting a process from a networked and/or crypted
executable that, for confidentiality, licensing or other reasons,
may not be written to the local file-systems.

The code that does that was already included in the Linux kernel by the
CRIU group, in the form of "prctl(PR_SET_MM)", but prior to this was
enclosed within their private "#ifdef CONFIG_CHECKPOINT_RESTORE", which is
normally disabled. The patch removes those ifdefs.

Signed-off-by: Amnon Shiloh <u3557@miso.sublimeip.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/timer.c: move some non timer related syscalls to kernel/sys.c

Andrew Morton noted:

akpm3:/usr/src/25> grep SYSCALL kernel/timer.c
SYSCALL_DEFINE1(alarm, unsigned int, seconds)
SYSCALL_DEFINE0(getpid)
SYSCALL_DEFINE0(getppid)
SYSCALL_DEFINE0(getuid)
SYSCALL_DEFINE0(geteuid)
SYSCALL_DEFINE0(getgid)
SYSCALL_DEFINE0(getegid)
SYSCALL_DEFINE0(gettid)
SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
COMPAT_SYSCALL_DEFINE1(sysinfo, struct compat_sysinfo __user *, info)

Only one of those should be in kernel/timer.c. Who wrote this thing?

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

PM / reboot: call syscore_shutdown() after disable_nonboot_cpus()

As commit 40dc166c (PM / Core: Introduce struct syscore_ops for core
subsystems PM) say, syscore_ops operations should be carried with one
CPU on-line and interrupts disabled. However, after commit f96972f2d
(kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()),
syscore_shutdown() is called before disable_nonboot_cpus(), so break
the rules. We have a MIPS machine with a 8259A PIC, and there is an
external timer (HPET) linked at 8259A. Since 8259A has been shutdown
too early (by syscore_shutdown()), disable_nonboot_cpus() runs without
timer interrupt, so it hangs and reboot fails. This patch call
syscore_shutdown() a little later (after disable_nonboot_cpus()) to
avoid reboot failure, this is the same way as poweroff does.

For consistency, add disable_nonboot_cpus() to kernel_halt().

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

poweroff: change orderly_poweroff() to use schedule_work()

David said:

Commit 6c0c0d4d1080 ("poweroff: fix bug in orderly_poweroff()")
apparently fixes one bug in orderly_poweroff(), but introduces
another. The comments on orderly_poweroff() claim it can be called
from any context - and indeed we call it from interrupt context in
arch/powerpc/platforms/pseries/ras.c for example. But since that
commit this is no longer safe, since call_usermodehelper_fns() is not
safe in interrupt context without the UMH_NO_WAIT option.

orderly_poweroff() can be used from any context but UMH_WAIT_EXEC is
sleepable. Move the "force" logic into __orderly_poweroff() and change
orderly_poweroff() to use the global poweroff_work which simply calls
__orderly_poweroff().

While at it, remove the unneeded "int argc" and change argv_split() to
use GFP_KERNEL.

We use the global "bool poweroff_force" to pass the argument, this can
obviously affect the previous request if it is pending/running. So we
only allow the "false => true" transition assuming that the pending
"true" should succeed anyway. If schedule_work() fails after that we
know that work->func() was not called yet, it must see the new value.

This means that orderly_poweroff() becomes async even if we do not run
the command and always succeeds, schedule_work() can only fail if the
work is already pending. We can export __orderly_poweroff() and change
the non-atomic callers which want the old semantics.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reported-by: David Gibson <david@gibson.dropbear.id.au>
Cc: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Feng Hong <hongfeng@marvell.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

switch getrusage() to COMPAT_SYSCALL_DEFINE

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

usermodehelper: cleanup/fix __orderly_poweroff() && argv_free()

__orderly_poweroff() does argv_free() if call_usermodehelper_fns()
returns -ENOMEM. As Lucas pointed out, this can be wrong if -ENOMEM was
not triggered by the failing call_usermodehelper_setup(), in this case
both __orderly_poweroff() and argv_cleanup() can do kfree().

Kill argv_cleanup() and change __orderly_poweroff() to call argv_free()
unconditionally like do_coredump() does. This info->cleanup() is not
needed (and wrong) since 6c0c0d4d "fix bug in orderly_poweroff() which
did the UMH_NO_WAIT => UMH_WAIT_EXEC change, we can rely on the fact
that CLONE_VFORK can't return until do_execve() succeeds/fails.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: hongfeng <hongfeng@marvell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

sys_prctl(): coding-style cleanup

Remove a tabstop from the switch statement, in the usual fashion. A few
instances of weirdwrapping were removed as a result.

Cc: Chen Gang <gang.chen@asianux.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sys_prctl(): arg2 is unsigned long which is never < 0

arg2 will never < 0, for its type is 'unsigned long'

Also, use the provided macros.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

userns: Allow unprivileged reboot

In a container with its own pid namespace and user namespace, rebooting
the system won't reboot the host, but terminate all the processes in
it and thus have the container shutdown, so it's safe.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

cputime: Rename thread_group_times to thread_group_cputime_adjusted

We have thread_group_cputime() and thread_group_times(). The naming
doesn't provide enough information about the difference between
these two APIs.

To lower the confusion, rename thread_group_times() to
thread_group_cputime_adjusted(). This name better suggests that
it's a version of thread_group_cputime() that does some stabilization
on the raw cputime values. ie here: scale on top of CFS runtime
stats and bound lower value for monotonicity.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>

use clamp_t in UNAME26 fix

The min/max call needed to have explicit types on some architectures
(e.g. mn10300). Use clamp_t instead to avoid the warning:

kernel/sys.c: In function 'override_release':
kernel/sys.c:1287:10: warning: comparison of distinct pointer types lacks a cast [enabled by default]

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: fix stack memory content leak via UNAME26

Calling uname() with the UNAME26 personality set allows a leak of kernel
stack contents. This fixes it by defensively calculating the length of
copy_to_user() call, making the len argument unsigned, and initializing
the stack buffer to zero (now technically unneeded, but hey, overkill).

CVE-2012-0957

Reported-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

poweroff: fix bug in orderly_poweroff()

orderly_poweroff is trying to poweroff platform in two steps:

step 1: Call user space application to poweroff
step 2: If user space poweroff fail, then do a force power off if force param
is set.

The bug here is, step 1 is always successful with param UMH_NO_WAIT, which obey
the design goal of orderly_poweroff.

We have two choices here:
UMH_WAIT_EXEC which means wait for the exec, but not the process;
UMH_WAIT_PROC which means wait for the process to complete.
we need to trade off the two choices:

If using UMH_WAIT_EXEC, there is potential issue comments by Serge E.
Hallyn: The exec will have started, but may for whatever (very unlikely)
reason fail.

If using UMH_WAIT_PROC, there is potential issue comments by Eric W.
Biederman: If the caller is not running in a kernel thread then we can
easily get into a case where the user space caller will block waiting for
us when we are waiting for the user space caller.

Thanks for their excellent ideas, based on the above discussion, we
finally choose UMH_WAIT_EXEC, which is much more safe, if the user
application really fails, we just complain the application itself, it
seems a better choice here.

Signed-off-by: Feng Hong <hongfeng@marvell.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()

As kernel_power_off() calls disable_nonboot_cpus(), we may also want to
have kernel_restart() call disable_nonboot_cpus(). Doing so can help
machines that require boot cpu be the last alive cpu during reboot to
survive with kernel restart.

This fixes one reboot issue seen on imx6q (Cortex-A9 Quad). The machine
requires that the restart routine be run on the primary cpu rather than
secondary ones. Otherwise, the secondary core running the restart
routine will fail to come to online after reboot.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

switch simple cases of fget_light to fdget

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

switch prctl_set_mm_exe_file() to fget_light()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

kernel/sys.c: avoid argv_free(NULL)

If argv_split() failed, the code will end up calling argv_free(NULL). Fix
it up and clean things up a bit.

Addresses Coverity report 703573.

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl: remove redunant assignment of "error" to zero

Just setting the "error" to error number is enough on failure and It
doesn't require to set "error" variable to zero in each switch case,
since it was already initialized with zero. And also removed return 0
in switch case with break statement

Signed-off-by: Sasikantha babu <sasikanth.v19@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: less paranoid prctl_set_mm_exe_file()

"no other files mapped" requirement from my previous patch (c/r: prctl:
update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal) is too
paranoid, it forbids operation even if there mapped one shared-anon vma.

Let's check that current mm->exe_file already unmapped, in this case
exe_file symlink already outdated and its changing is reasonable.

Plus, this patch fixes exit code in case operation success.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: Move PR_GET_TID_ADDRESS to a proper place

During merging of PR_GET_TID_ADDRESS patch the code has been misplaced (it
happened to appear under PR_MCE_KILL) in result noone can use this option.

Fix it by moving code snippet to a proper place.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: drop VMA flags test on PR_SET_MM_ stack data assignment

In commit b76437579d13 ("procfs: mark thread stack correctly in
proc/<pid>/maps") the stack allocated via clone() is marked in
/proc/<pid>/maps as [stack:%d] thus it might be out of the former
mm->start_stack/end_stack values (and even has some custom VMA flags
set).

So to be able to restore mm->start_stack/end_stack drop vma flags test,
but still require the underlying VMA to exist.

As always note this feature is under CONFIG_CHECKPOINT_RESTORE and
requires CAP_SYS_RESOURCE to be granted.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: add ability to get clear_tid_address

Zero is written at clear_tid_address when the process exits. This
functionality is used by pthread_join().

We already have sys_set_tid_address() to change this address for the
current task but there is no way to obtain it from user space.

Without the ability to find this address and dump it we can't restore
pthread'ed apps which call pthread_join() once they have been restored.

This patch introduces the PR_GET_TID_ADDRESS prctl option which allows
the current process to obtain own clear_tid_address.

This feature is available iif CONFIG_CHECKPOINT_RESTORE is set.

[akpm@linux-foundation.org: fix prctl numbering]
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pedro Alves <palves@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: add minimal address test to PR_SET_MM

Make sure the address being set is greater than mmap_min_addr (as
suggested by Kees Cook).

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal

A fix for commit b32dfe377102 ("c/r: prctl: add ability to set new
mm_struct::exe_file").

After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until
final mmput(), it never becomes NULL while task is alive.

We can check for other mapped files in mm instead of checking
mm->num_exe_file_vmas, and mark mm with flag MMF_EXE_FILE_CHANGED in
order to forbid second changing of mm->exe_file.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: add ability to set new mm_struct::exe_file

When we do restore we would like to have a way to setup a former
mm_struct::exe_file so that /proc/pid/exe would point to the original
executable file a process had at checkpoint time.

For this the PR_SET_MM_EXE_FILE code is introduced. This option takes a
file descriptor which will be set as a source for new /proc/$pid/exe
symlink.

Note it allows to change /proc/$pid/exe if there are no VM_EXECUTABLE
vmas present for current process, simply because this feature is a special
to C/R and mm::num_exe_file_vmas become meaningless after that.

To minimize the amount of transition the /proc/pid/exe symlink might have,
this feature is implemented in one-shot manner. Thus once changed the
symlink can't be changed again. This should help sysadmins to monitor the
symlinks over all process running in a system.

In particular one could make a snapshot of processes and ring alarm if
there unexpected changes of /proc/pid/exe's in a system.

Note -- this feature is available iif CONFIG_CHECKPOINT_RESTORE is set and
the caller must have CAP_SYS_RESOURCE capability granted, otherwise the
request to change symlink will be rejected.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: extend PR_SET_MM to set up more mm_struct entries

During checkpoint we dump whole process memory to a file and the dump
includes process stack memory. But among stack data itself, the stack
carries additional parameters such as command line arguments, environment
data and auxiliary vector.

So when we do restore procedure and once we've restored stack data itself
we need to setup mm_struct::arg_start/end, env_start/end, so restored
process would be able to find command line arguments and environment data
it had at checkpoint time. The same applies to auxiliary vector.

For this reason additional PR_SET_MM_(ARG_START | ARG_END | ENV_START |
ENV_END | AUXV) codes are introduced.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kmod: convert two call sites to call_usermodehelper_fns()

Both kernel/sys.c && security/keys/request_key.c where inlining the exact
same code as call_usermodehelper_fns(); So simply convert these sites to
directly use call_usermodehelper_fns().

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sethostname/setdomainname: notify userspace when there is a change in uts_kern_table

sethostname() and setdomainname() notify userspace on failure (without
modifying uts_kern_table). Change things so that we only notify userspace
on success, when uts_kern_table was actually modified.

Signed-off-by: Sasikantha babu <sasikanth.v19@gmail.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: WANG Cong <amwang@redhat.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

userns: Convert ptrace, kill, set_priority permission checks to work with kuids and kgids

Update the permission checks to use the new uid_eq and gid_eq helpers
and remove the now unnecessary user_ns equality comparison.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

userns: Convert setting and getting uid and gid system calls to use kuid and kgid

Convert setregid, setgid, setreuid, setuid,
setresuid, getresuid, setresgid, getresgid, setfsuid, setfsgid,
getuid, geteuid, getgid, getegid,
waitpid, waitid, wait4.

Convert userspace uids and gids into kuids and kgids before
being placed on struct cred. Convert struct cred kuids and
kgids into userspace uids and gids when returning them.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

userns: Store uid and gid values in struct cred with kuid_t and kgid_t types

cred.h and a few trivial users of struct cred are changed. The rest of the users
of struct cred are left for other patches as there are too many changes to make
in one go and leave the change reviewable. If the user namespace is disabled and
CONFIG_UIDGID_STRICT_TYPE_CHECKS are disabled the code will contiue to compile
and behave correctly.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

seccomp: add system call filtering using BPF

[This patch depends on luto@mit.edu's no_new_privs patch:
https://lkml.org/lkml/2012/1/30/264
The whole series including Andrew's patches can be found here:
https://github.com/redpig/linux/tree/seccomp
Complete diff here:
https://github.com/redpig/linux/compare/1dc65fed...seccomp
]

This patch adds support for seccomp mode 2. Mode 2 introduces the
ability for unprivileged processes to install system call filtering
policy expressed in terms of a Berkeley Packet Filter (BPF) program.
This program will be evaluated in the kernel for each system call
the task makes and computes a result based on data in the format
of struct seccomp_data.

A filter program may be installed by calling:
struct sock_fprog fprog = { ... };
...
prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &fprog);

The return value of the filter program determines if the system call is
allowed to proceed or denied. If the first filter program installed
allows prctl(2) calls, then the above call may be made repeatedly
by a task to further reduce its access to the kernel. All attached
programs must be evaluated before a system call will be allowed to
proceed.

Filter programs will be inherited across fork/clone and execve.
However, if the task attaching the filter is unprivileged
(!CAP_SYS_ADMIN) the no_new_privs bit will be set on the task. This
ensures that unprivileged tasks cannot attach filters that affect
privileged tasks (e.g., setuid binary).

There are a number of benefits to this approach. A few of which are
as follows:
- BPF has been exposed to userland for a long time
- BPF optimization (and JIT'ing) are well understood
- Userland already knows its ABI: system call numbers and desired
arguments
- No time-of-check-time-of-use vulnerable data accesses are possible.
- system call arguments are loaded on access only to minimize copying
required for system call policy decisions.

Mode 2 support is restricted to architectures that enable
HAVE_ARCH_SECCOMP_FILTER. In this patch, the primary dependency is on
syscall_get_arguments(). The full desired scope of this feature will
add a few minor additional requirements expressed later in this series.
Based on discussion, SECCOMP_RET_ERRNO and SECCOMP_RET_TRACE seem to be
the desired additional functionality.

No architectures are enabled in this patch.

Signed-off-by: Will Drewry <wad@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Reviewed-by: Indan Zupancic <indan@nul.nu>
Acked-by: Eric Paris <eparis@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>

v18: - rebase to v3.4-rc2
- s/chk/check/ (akpm@linux-foundation.org,jmorris@namei.org)
- allocate with GFP_KERNEL|__GFP_NOWARN (indan@nul.nu)
- add a comment for get_u32 regarding endianness (akpm@)
- fix other typos, style mistakes (akpm@)
- added acked-by
v17: - properly guard seccomp filter needed headers (leann@ubuntu.com)
- tighten return mask to 0x7fff0000
v16: - no change
v15: - add a 4 instr penalty when counting a path to account for seccomp_filter
size (indan@nul.nu)
- drop the max insns to 256KB (indan@nul.nu)
- return ENOMEM if the max insns limit has been hit (indan@nul.nu)
- move IP checks after args (indan@nul.nu)
- drop !user_filter check (indan@nul.nu)
- only allow explicit bpf codes (indan@nul.nu)
- exit_code -> exit_sig
v14: - put/get_seccomp_filter takes struct task_struct
(indan@nul.nu,keescook@chromium.org)
- adds seccomp_chk_filter and drops general bpf_run/chk_filter user
- add seccomp_bpf_load for use by net/core/filter.c
- lower max per-process/per-hierarchy: 1MB
- moved nnp/capability check prior to allocation
(all of the above: indan@nul.nu)
v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc
v12: - added a maximum instruction count per path (indan@nul.nu,oleg@redhat.com)
- removed copy_seccomp (keescook@chromium.org,indan@nul.nu)
- reworded the prctl_set_seccomp comment (indan@nul.nu)
v11: - reorder struct seccomp_data to allow future args expansion (hpa@zytor.com)
- style clean up, @compat dropped, compat_sock_fprog32 (indan@nul.nu)
- do_exit(SIGSYS) (keescook@chromium.org, luto@mit.edu)
- pare down Kconfig doc reference.
- extra comment clean up
v10: - seccomp_data has changed again to be more aesthetically pleasing
(hpa@zytor.com)
- calling convention is noted in a new u32 field using syscall_get_arch.
This allows for cross-calling convention tasks to use seccomp filters.
(hpa@zytor.com)
- lots of clean up (thanks, Indan!)
v9: - n/a
v8: - use bpf_chk_filter, bpf_run_filter. update load_fns
- Lots of fixes courtesy of indan@nul.nu:
-- fix up load behavior, compat fixups, and merge alloc code,
-- renamed pc and dropped __packed, use bool compat.
-- Added a hidden CONFIG_SECCOMP_FILTER to synthesize non-arch
dependencies
v7: (massive overhaul thanks to Indan, others)
- added CONFIG_HAVE_ARCH_SECCOMP_FILTER
- merged into seccomp.c
- minimal seccomp_filter.h
- no config option (part of seccomp)
- no new prctl
- doesn't break seccomp on systems without asm/syscall.h
(works but arg access always fails)
- dropped seccomp_init_task, extra free functions, ...
- dropped the no-asm/syscall.h code paths
- merges with network sk_run_filter and sk_chk_filter
v6: - fix memory leak on attach compat check failure
- require no_new_privs || CAP_SYS_ADMIN prior to filter
installation. (luto@mit.edu)
- s/seccomp_struct_/seccomp_/ for macros/functions (amwang@redhat.com)
- cleaned up Kconfig (amwang@redhat.com)
- on block, note if the call was compat (so the # means something)
v5: - uses syscall_get_arguments
(indan@nul.nu,oleg@redhat.com, mcgrathr@chromium.org)
- uses union-based arg storage with hi/lo struct to
handle endianness. Compromises between the two alternate
proposals to minimize extra arg shuffling and account for
endianness assuming userspace uses offsetof().
(mcgrathr@chromium.org, indan@nul.nu)
- update Kconfig description
- add include/seccomp_filter.h and add its installation
- (naive) on-demand syscall argument loading
- drop seccomp_t (eparis@redhat.com)
v4: - adjusted prctl to make room for PR_[SG]ET_NO_NEW_PRIVS
- now uses current->no_new_privs
(luto@mit.edu,torvalds@linux-foundation.com)
- assign names to seccomp modes (rdunlap@xenotime.net)
- fix style issues (rdunlap@xenotime.net)
- reworded Kconfig entry (rdunlap@xenotime.net)
v3: - macros to inline (oleg@redhat.com)
- init_task behavior fixed (oleg@redhat.com)
- drop creator entry and extra NULL check (oleg@redhat.com)
- alloc returns -EINVAL on bad sizing (serge.hallyn@canonical.com)
- adds tentative use of "always_unprivileged" as per
torvalds@linux-foundation.org and luto@mit.edu
v2: - (patch 2 only)
Signed-off-by: James Morris <james.l.morris@oracle.com>

Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs

With this change, calling
prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)
disables privilege granting operations at execve-time. For example, a
process will not be able to execute a setuid binary to change their uid
or gid if this bit is set. The same is true for file capabilities.

Additionally, LSM_UNSAFE_NO_NEW_PRIVS is defined to ensure that
LSMs respect the requested behavior.

To determine if the NO_NEW_PRIVS bit is set, a task may call
prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0);
It returns 1 if set and 0 if it is not set. If any of the arguments are
non-zero, it will return -1 and set errno to -EINVAL.
(PR_SET_NO_NEW_PRIVS behaves similarly.)

This functionality is desired for the proposed seccomp filter patch
series. By using PR_SET_NO_NEW_PRIVS, it allows a task to modify the
system call behavior for itself and its child tasks without being
able to impact the behavior of a more privileged task.

Another potential use is making certain privileged operations
unprivileged. For example, chroot may be considered "safe" if it cannot
affect privileged tasks.

Note, this patch causes execve to fail when PR_SET_NO_NEW_PRIVS is
set and AppArmor is in use. It is fixed in a subsequent patch.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Will Drewry <wad@chromium.org>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>

v18: updated change desc
v17: using new define values as per 3.4
Signed-off-by: James Morris <james.l.morris@oracle.com>

userns: Disassociate user_struct from the user_namespace.

Modify alloc_uid to take a kuid and make the user hash table global.
Stop holding a reference to the user namespace in struct user_struct.

This simplifies the code and makes the per user accounting not
care about which user namespace a uid happens to appear in.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

userns: Add kuid_t and kgid_t and associated infrastructure in uidgid.h

Start distinguishing between internal kernel uids and gids and
values that userspace can use. This is done by introducing two
new types: kuid_t and kgid_t. These types and their associated
functions are infrastructure are declared in the new header
uidgid.h.

Ultimately there will be a different implementation of the mapping
functions for use with user namespaces. But to keep it simple
we introduce the mapping functions first to separate the meat
from the mechanical code conversions.

Export overflowuid and overflowgid so we can use from_kuid_munged
and from_kgid_munged in modular code.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

userns: Use cred->user_ns instead of cred->user->user_ns

Optimize performance and prepare for the removal of the user_ns reference
from user_struct. Remove the slow long walk through cred->user->user_ns and
instead go straight to cred->user_ns.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

userns: Remove unnecessary cast to struct user_struct when copying cred->user.

In struct cred the user member is and has always been declared struct user_struct *user.
At most a constant struct cred will have a constant pointer to non-constant user_struct
so remove this unnecessary cast.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

pidns: add reboot_pid_ns() to handle the reboot syscall

In the case of a child pid namespace, rebooting the system does not really
makes sense. When the pid namespace is used in conjunction with the other
namespaces in order to create a linux container, the reboot syscall leads
to some problems.

A container can reboot the host. That can be fixed by dropping the
sys_reboot capability but we are unable to correctly to poweroff/
halt/reboot a container and the container stays stuck at the shutdown time
with the container's init process waiting indefinitively.

After several attempts, no solution from userspace was found to reliabily
handle the shutdown from a container.

This patch propose to make the init process of the child pid namespace to
exit with a signal status set to : SIGINT if the child pid namespace
called "halt/poweroff" and SIGHUP if the child pid namespace called
"reboot". When the reboot syscall is called and we are not in the initial
pid namespace, we kill the pid namespace for "HALT", "POWEROFF",
"RESTART", and "RESTART2". Otherwise we return EINVAL.

Returning EINVAL is also an easy way to check if this feature is supported
by the kernel when invoking another 'reboot' option like CAD.

By this way the parent process of the child pid namespace knows if it
rebooted or not and can take the right decision.

Test case:
==========

#include <alloca.h>
#include <stdio.h>
#include <sched.h>
#include <unistd.h>
#include <signal.h>
#include <sys/reboot.h>
#include <sys/types.h>
#include <sys/wait.h>

#include <linux/reboot.h>

static int do_reboot(void *arg)
{
int *cmd = arg;

if (reboot(*cmd))
printf("failed to reboot(%d): %m\n", *cmd);
}

int test_reboot(int cmd, int sig)
{
long stack_size = 4096;
void *stack = alloca(stack_size) + stack_size;
int status;
pid_t ret;

ret = clone(do_reboot, stack, CLONE_NEWPID | SIGCHLD, &cmd);
if (ret < 0) {
printf("failed to clone: %m\n");
return -1;
}

if (wait(&status) < 0) {
printf("unexpected wait error: %m\n");
return -1;
}

if (!WIFSIGNALED(status)) {
printf("child process exited but was not signaled\n");
return -1;
}

if (WTERMSIG(status) != sig) {
printf("signal termination is not the one expected\n");
return -1;
}

return 0;
}

int main(int argc, char *argv[])
{
int status;

status = test_reboot(LINUX_REBOOT_CMD_RESTART, SIGHUP);
if (status < 0)
return 1;
printf("reboot(LINUX_REBOOT_CMD_RESTART) succeed\n");

status = test_reboot(LINUX_REBOOT_CMD_RESTART2, SIGHUP);
if (status < 0)
return 1;
printf("reboot(LINUX_REBOOT_CMD_RESTART2) succeed\n");

status = test_reboot(LINUX_REBOOT_CMD_HALT, SIGINT);
if (status < 0)
return 1;
printf("reboot(LINUX_REBOOT_CMD_HALT) succeed\n");

status = test_reboot(LINUX_REBOOT_CMD_POWER_OFF, SIGINT);
if (status < 0)
return 1;
printf("reboot(LINUX_REBOOT_CMD_POWERR_OFF) succeed\n");

status = test_reboot(LINUX_REBOOT_CMD_CAD_ON, -1);
if (status >= 0) {
printf("reboot(LINUX_REBOOT_CMD_CAD_ON) should have failed\n");
return 1;
}
printf("reboot(LINUX_REBOOT_CMD_CAD_ON) has failed as expected\n");

return 0;
}

[akpm@linux-foundation.org: tweak and add comments]
[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Tested-by: Serge Hallyn <serge.hallyn@canonical.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl: add PR_{SET,GET}_CHILD_SUBREAPER to allow simple process supervision

Userspace service managers/supervisors need to track their started
services. Many services daemonize by double-forking and get implicitly
re-parented to PID 1. The service manager will no longer be able to
receive the SIGCHLD signals for them, and is no longer in charge of
reaping the children with wait(). All information about the children is
lost at the moment PID 1 cleans up the re-parented processes.

With this prctl, a service manager process can mark itself as a sort of
'sub-init', able to stay as the parent for all orphaned processes
created by the started services. All SIGCHLD signals will be delivered
to the service manager.

Receiving SIGCHLD and doing wait() is in cases of a service-manager much
preferred over any possible asynchronous notification about specific
PIDs, because the service manager has full access to the child process
data in /proc and the PID can not be re-used until the wait(), the
service-manager itself is in charge of, has happened.

As a side effect, the relevant parent PID information does not get lost
by a double-fork, which results in a more elaborate process tree and
'ps' output:

before:
# ps afx
253 ? Ss 0:00 /bin/dbus-daemon --system --nofork
294 ? Sl 0:00 /usr/libexec/polkit-1/polkitd
328 ? S 0:00 /usr/sbin/modem-manager
608 ? Sl 0:00 /usr/libexec/colord
658 ? Sl 0:00 /usr/libexec/upowerd
819 ? Sl 0:00 /usr/libexec/imsettings-daemon
916 ? Sl 0:00 /usr/libexec/udisks-daemon
917 ? S 0:00 \_ udisks-daemon: not polling any devices

after:
# ps afx
294 ? Ss 0:00 /bin/dbus-daemon --system --nofork
426 ? Sl 0:00 \_ /usr/libexec/polkit-1/polkitd
449 ? S 0:00 \_ /usr/sbin/modem-manager
635 ? Sl 0:00 \_ /usr/libexec/colord
705 ? Sl 0:00 \_ /usr/libexec/upowerd
959 ? Sl 0:00 \_ /usr/libexec/udisks-daemon
960 ? S 0:00 | \_ udisks-daemon: not polling any devices
977 ? Sl 0:00 \_ /usr/libexec/packagekitd

This prctl is orthogonal to PID namespaces. PID namespaces are isolated
from each other, while a service management process usually requires the
services to live in the same namespace, to be able to talk to each
other.

Users of this will be the systemd per-user instance, which provides
init-like functionality for the user's login session and D-Bus, which
activates bus services on-demand. Both need init-like capabilities to
be able to properly keep track of the services they start.

Many thanks to Oleg for several rounds of review and insights.

[akpm@linux-foundation.org: fix comment layout and spelling]
[akpm@linux-foundation.org: add lengthy code comment from Oleg]
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Acked-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

prctl: use CAP_SYS_RESOURCE for PR_SET_MM option

CAP_SYS_ADMIN is already overloaded left and right, so to have more
fine-grained access control use CAP_SYS_RESOURCE here.

The CAP_SYS_RESOUCE is chosen because this prctl option allows a current
process to adjust some fields of memory map descriptor which rather
represents what the process owns: pointers to code, data, stack
segments, command line, auxiliary vector data and etc.

Suggested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

c/r: prctl: add PR_SET_MM codes to set up mm_struct entries

When we restore a task we need to set up text, data and data heap sizes
from userspace to the values a task had at checkpoint time. This patch
adds auxilary prctl codes for that.

While most of them have a statistical nature (their values are involved
into calculation of /proc/<pid>/statm output) the start_brk and brk values
are used to compute an allowed size of program data segment expansion.
Which means an arbitrary changes of this values might be dangerous
operation. So to restrict access the following requirements applied to
prctl calls:

- The process has to have CAP_SYS_ADMIN capability granted.
- For all opcodes except start_brk/brk members an appropriate
VMA area must exist and should fit certain VMA flags,
such as:
- code segment must be executable but not writable;
- data segment must not be executable.

start_brk/brk values must not intersect with data segment and must not
exceed RLIMIT_DATA resource limit.

Still the main guard is CAP_SYS_ADMIN capability check.

Note the kernel should be compiled with CONFIG_CHECKPOINT_RESTORE support
otherwise these prctl calls will return -EINVAL.

[akpm@linux-foundation.org: cache current->mm in a local, saving 200 bytes text]
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[S390] cputime: add sparse checking and cleanup

Make cputime_t and cputime64_t nocast to enable sparse checking to
detect incorrect use of cputime. Drop the cputime macros for simple
scalar operations. The conversion macros are still needed.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

sysctl: add support for poll()

Adding support for poll() in sysctl fs allows userspace to receive
notifications of changes in sysctl entries. This adds a infrastructure to
allow files in sysctl fs to be pollable and implements it for hostname and
domainname.

[akpm@linux-foundation.org: s/declare/define/ for definitions]
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Greg KH <gregkh@suse.de>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel: fix several implicit usasges of kmod.h

These files were implicitly relying on <linux/kmod.h> coming in via
module.h, as without it we get things like:

kernel/power/suspend.c:100: error: implicit declaration of function ‘usermodehelper_disable’
kernel/power/suspend.c:109: error: implicit declaration of function ‘usermodehelper_enable’
kernel/power/user.c:254: error: implicit declaration of function ‘usermodehelper_disable’
kernel/power/user.c:261: error: implicit declaration of function ‘usermodehelper_enable’

kernel/sys.c:317: error: implicit declaration of function ‘usermodehelper_disable’
kernel/sys.c:1816: error: implicit declaration of function ‘call_usermodehelper_setup’
kernel/sys.c:1822: error: implicit declaration of function ‘call_usermodehelper_setfns’
kernel/sys.c:1824: error: implicit declaration of function ‘call_usermodehelper_exec’

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

kernel: Map most files to use export.h instead of module.h

The changed files were only including linux/module.h for the
EXPORT_SYMBOL infrastructure, and nothing else. Revector them
onto the isolated export header for faster compile times.

Nothing to see here but a whole lot of instances of:

-#include <linux/module.h>
+#include <linux/export.h>

This commit is only changing the kernel dir; next targets
will probably be mm, fs, the arch dirs, etc.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

Avoid using variable-length arrays in kernel/sys.c

The size is always valid, but variable-length arrays generate worse code
for no good reason (unless the function happens to be inlined and the
compiler sees the length for the simple constant it is).

Also, there seems to be some code generation problem on POWER, where
Henrik Bakken reports that register r28 can get corrupted under some
subtle circumstances (interrupt happening at the wrong time?). That all
indicates some seriously broken compiler issues, but since variable
length arrays are bad regardless, there's little point in trying to
chase it down.

"Just don't do that, then".

Reported-by: Henrik Grindal Bakken <henribak@cisco.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

connector: add comm change event report to proc connector

Add an event to monitor comm value changes of tasks. Such an event
becomes vital, if someone desires to control threads of a process in
different manner.

A natural characteristic of threads is its comm value, and helpfully
application developers have an opportunity to change it in runtime.
Reporting about such events via proc connector allows to fine-grain
monitoring and control potentials, for instance a process control daemon
listening to proc connector and following comm value policies can place
specific threads to assigned cgroup partitions.

It might be possible to achieve a pale partial one-shot likeness without
this update, if an application changes comm value of a thread generator
task beforehand, then a new thread is cloned, and after that proc
connector listener gets the fork event and reads new thread's comm value
from procfs stat file, but this change visibly simplifies and extends the
matter.

Signed-off-by: Vladimir Zapolskiy <vzapolskiy@gmail.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add a personality to report 2.6.x version numbers

I ran into a couple of programs which broke with the new Linux 3.0
version. Some of those were binary only. I tried to use LD_PRELOAD to
work around it, but it was quite difficult and in one case impossible
because of a mix of 32bit and 64bit executables.

For example, all kind of management software from HP doesnt work, unless
we pretend to run a 2.6 kernel.

$ uname -a
Linux svivoipvnx001 3.0.0-08107-g97cd98f #1062 SMP Fri Aug 12 18:11:45 CEST 2011 i686 i686 i386 GNU/Linux

$ hpacucli ctrl all show

Error: No controllers detected.

$ rpm -qf /usr/sbin/hpacucli
hpacucli-8.75-12.0

Another notable case is that Python now reports "linux3" from
sys.platform(); which in turn can break things that were checking
sys.platform() == "linux2":

https://bugzilla.mozilla.org/show_bug.cgi?id=664564

It seems pretty clear to me though it's a bug in the apps that are using
'==' instead of .startswith(), but this allows us to unbreak broken
programs.

This patch adds a UNAME26 personality that makes the kernel report a
2.6.40+x version number instead. The x is the x in 3.x.

I know this is somewhat ugly, but I didn't find a better workaround, and
compatibility to existing programs is important.

Some programs also read /proc/sys/kernel/osrelease. This can be worked
around in user space with mount --bind (and a mount namespace)

To use:

wget ftp://ftp.kernel.org/pub/linux/kernel/people/ak/uname26/uname26.c
gcc -o uname26 uname26.c
./uname26 program

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

move RLIMIT_NPROC check from set_user() to do_execve_common()

The patch http://lkml.org/lkml/2003/7/13/226 introduced an RLIMIT_NPROC
check in set_user() to check for NPROC exceeding via setuid() and
similar functions.

Before the check there was a possibility to greatly exceed the allowed
number of processes by an unprivileged user if the program relied on
rlimit only. But the check created new security threat: many poorly
written programs simply don't check setuid() return code and believe it
cannot fail if executed with root privileges. So, the check is removed
in this patch because of too often privilege escalations related to
buggy programs.

The NPROC can still be enforced in the common code flow of daemons
spawning user processes. Most of daemons do fork()+setuid()+execve().
The check introduced in execve() (1) enforces the same limit as in
setuid() and (2) doesn't create similar security issues.

Neil Brown suggested to track what specific process has exceeded the
limit by setting PF_NPROC_EXCEEDED process flag. With the change only
this process would fail on execve(), and other processes' execve()
behaviour is not changed.

Solar Designer suggested to re-check whether NPROC limit is still
exceeded at the moment of execve(). If the process was sleeping for
days between set*uid() and execve(), and the NPROC counter step down
under the limit, the defered execve() failure because NPROC limit was
exceeded days ago would be unexpected. If the limit is not exceeded
anymore, we clear the flag on successful calls to execve() and fork().

The flag is also cleared on successful calls to set_user() as the limit
was exceeded for the previous user, not the current one.

Similar check was introduced in -ow patches (without the process flag).

v3 - clear PF_NPROC_EXCEEDED on successful calls to set_user().

Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

notifiers: sys: move reboot notifiers into reboot.h

It is not necessary to share the same notifier.h.

This patch already moves register_reboot_notifier() and
unregister_reboot_notifier() from kernel/notifier.c to kernel/sys.c.

[amwang@redhat.com: make allyesconfig succeed on ppc64]
Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: David Miller <davem@davemloft.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: WANG Cong <amwang@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

PM: Remove sysdev suspend, resume and shutdown operations

Since suspend, resume and shutdown operations in struct sysdev_class
and struct sysdev_driver are not used any more, remove them. Also
drop sysdev_suspend(), sysdev_resume() and sysdev_shutdown() used
for executing those operations and modify all of their users
accordingly. This reduces kernel code size quite a bit and reduces
its complexity.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>

reboot: disable usermodehelper to prevent fs access

In case CONFIG_UEVENT_HELPER_PATH is not set to "", which it
should be on every system, the kernel forks processes during
shutdown, which try to access the rootfs, even when the
binary does not exist. It causes exceptions and long delays in
the disk driver, which gets read requests at the time it tries
to shut down the disk.

This patch disables all kernel-forked processes during reboot to
allow a clean poweroff.

Cc: Tejun Heo <htejun@gmail.com>
Tested-By: Anton Guda <atu@dmeti.dp.ua>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

userns: user namespaces: convert all capable checks in kernel/sys.c

This allows setuid/setgid in containers. It also fixes some corner cases
where kernel logic foregoes capability checks when uids are equivalent.
The latter will need to be done throughout the whole kernel.

Changelog:
Jan 11: Use nsown_capable() as suggested by Bastian Blank.
Jan 11: Fix logic errors in uid checks pointed out by Bastian.
Feb 15: allow prlimit to current (was regression in previous version)
Feb 23: remove debugging printks, uninline set_one_prio_perm and
make it bool, and document its return value.

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

userns: allow sethostname in a container

Changelog:
Feb 23: let clone_uts_ns() handle setting uts->user_ns
To do so we need to pass in the task_struct who'll
get the utsname, so we can get its user_ns.
Feb 23: As per Oleg's coment, just pass in tsk, instead of two
of its members.

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

PM / Core: Introduce struct syscore_ops for core subsystems PM

Some subsystems need to carry out suspend/resume and shutdown
operations with one CPU on-line and interrupts disabled. The only
way to register such operations is to define a sysdev class and
a sysdev specifically for this purpose which is cumbersome and
inefficient. Moreover, the arguments taken by sysdev suspend,
resume and shutdown callbacks are practically never necessary.

For this reason, introduce a simpler interface allowing subsystems
to register operations to be executed very late during system suspend
and shutdown and very early during resume in the form of
strcut syscore_ops objects.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>

Fix prlimit64 for suid/sgid processes

Since check_prlimit_permission always fails in the case of SUID/GUID
processes, such processes are not able to read or set their own limits.
This commit changes this by assuming that process can always read/change
its own limits.

Signed-off-by: Kacper Kornet <kornet@camk.edu.pl>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kmsg_dump: add kmsg_dump() calls to the reboot, halt, poweroff and emergency_restart paths

We need to know the reason why system rebooted in support service.
However, we can't inform our customers of the reason because final
messages are lost on current Linux kernel.

This patch improves the situation above because the final messages are
saved by adding kmsg_dump() to reboot, halt, poweroff and
emergency_restart path.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Marco Stornelli <marco.stornelli@gmail.com>
Reviewed-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched: Add 'autogroup' scheduling feature: automated per session task groups

A recurring complaint from CFS users is that parallel kbuild has
a negative impact on desktop interactivity. This patch
implements an idea from Linus, to automatically create task
groups. Currently, only per session autogroups are implemented,
but the patch leaves the way open for enhancement.

Implementation: each task's signal struct contains an inherited
pointer to a refcounted autogroup struct containing a task group
pointer, the default for all tasks pointing to the
init_task_group. When a task calls setsid(), a new task group
is created, the process is moved into the new task group, and a
reference to the preveious task group is dropped. Child
processes inherit this task group thereafter, and increase it's
refcount. When the last thread of a process exits, the
process's reference is dropped, such that when the last process
referencing an autogroup exits, the autogroup is destroyed.

At runqueue selection time, IFF a task has no cgroup assignment,
its current autogroup is used.

Autogroup bandwidth is controllable via setting it's nice level
through the proc filesystem:

cat /proc/<pid>/autogroup

Displays the task's group and the group's nice level.

echo <nice level> > /proc/<pid>/autogroup

Sets the task group's shares to the weight of nice <level> task.
Setting nice level is rate limited for !admin users due to the
abuse risk of task group locking.

The feature is enabled from boot by default if
CONFIG_SCHED_AUTOGROUP=y is selected, but can be disabled via
the boot option noautogroup, and can also be turned on/off on
the fly via:

echo [01] > /proc/sys/kernel/sched_autogroup_enabled

... which will automatically move tasks to/from the root task group.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Paul Turner <pjt@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
[ Removed the task_group_path() debug code, and fixed !EVENTFD build failure. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1290281700.28711.9.camel@maggy.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>