device_cgroup: Fix kernel-doc warnings in device_cgroup

Fix kernel-doc warnings in device_cgroup:

security/device_cgroup.c:835: warning: Excess function parameter
'dev_cgroup' description in 'devcgroup_legacy_check_permission'.

Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

lsm: fix a number of misspellings

A random collection of spelling fixes for source files in the LSM
layer.

Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

device_cgroup: Fix typo in devcgroup_css_alloc description

Fix the stale cgroup.c path in the devcgroup_css_alloc() description.

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

device_cgroup: Roll back to original exceptions after copy failure

When add the 'a *:* rwm' entry to devcgroup A's whitelist, at first A's
exceptions will be cleaned and A's behavior is changed to
DEVCG_DEFAULT_ALLOW. Then parent's exceptions will be copyed to A's
whitelist. If copy failure occurs, just return leaving A to grant
permissions to all devices. And A may grant more permissions than
parent.

Backup A's whitelist and recover original exceptions after copy
failure.

Cc: stable@vger.kernel.org
Fixes: 4cef7299b478 ("device_cgroup: add proper checking when changing default behavior")
Signed-off-by: Wang Weiyang <wangweiyang2@huawei.com>
Reviewed-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

bpf: Make BPF_PROG_RUN_ARRAY return -err instead of allow boolean

Right now BPF_PROG_RUN_ARRAY and related macros return 1 or 0
for whether the prog array allows or rejects whatever is being
hooked. The caller of these macros then return -EPERM or continue
processing based on thw macro's return value. Unforunately this is
inflexible, since -EPERM is the only err that can be returned.

This patch should be a no-op; it prepares for the next patch. The
returning of the -EPERM is moved to inside the macros, so the outer
functions are directly returning what the macros returned if they
are non-zero.

Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/788abcdca55886d1f43274c918eaa9f792a9f33b.1639619851.git.zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

add missing bpf-cgroup.h includes

We're about to break the cgroup-defs.h -> bpf-cgroup.h dependency,
make sure those who actually need more than the definition of
struct cgroup_bpf include bpf-cgroup.h explicitly.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/bpf/20211216025538.1649516-3-kuba@kernel.org

device_cgroup: Fix RCU list debugging warning

exceptions may be traversed using list_for_each_entry_rcu()
outside of an RCU read side critical section BUT under the
protection of decgroup_mutex. Hence add the corresponding
lockdep expression to fix the following false-positive
warning:

[ 2.304417] =============================
[ 2.304418] WARNING: suspicious RCU usage
[ 2.304420] 5.5.4-stable #17 Tainted: G E
[ 2.304422] -----------------------------
[ 2.304424] security/device_cgroup.c:355 RCU-list traversed in non-reader section!!

Signed-off-by: Amol Grover <frextrite@gmail.com>
Signed-off-by: James Morris <jmorris@namei.org>

device_cgroup: Cleanup cgroup eBPF device filter code

Original cgroup v2 eBPF code for filtering device access made it
possible to compile with CONFIG_CGROUP_DEVICE=n and still use the eBPF
filtering. Change
commit 4b7d4d453fc4 ("device_cgroup: Export devcgroup_check_permission")
reverted this, making it required to set it to y.

Since the device filtering (and all the docs) for cgroup v2 is no longer
a "device controller" like it was in v1, someone might compile their
kernel with CONFIG_CGROUP_DEVICE=n. Then (for linux 5.5+) the eBPF
filter will not be invoked, and all processes will be allowed access
to all devices, no matter what the eBPF filter says.

Signed-off-by: Odin Ugedal <odin@ugedal.com>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

device_cgroup: Export devcgroup_check_permission

For AMD compute (amdkfd) driver.

All AMD compute devices are exported via single device node /dev/kfd. As
a result devices cannot be controlled individually using device cgroup.

AMD compute devices will rely on its graphics counterpart that exposes
/dev/dri/renderN node for each device. For each task (based on its
cgroup), KFD driver will check if /dev/dri/renderN node is accessible
before exposing it.

Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan@amd.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

docs: cgroup-v1: add it to the admin-guide book

Those files belong to the admin guide, so add them.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

docs: cgroup-v1: convert docs to ReST and rename to *.rst

Convert the cgroup-v1 files to ReST format, in order to
allow a later addition to the admin-guide.

The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

device_cgroup: fix RCU imbalance in error case

When dev_exception_add() returns an error (due to a failed memory
allocation), make sure that we move the RCU preemption count back to where
it was before we were called. We dropped the RCU read lock inside the loop
body, so we can't just "break".

sparse complains about this, too:

$ make -s C=2 security/device_cgroup.o
./include/linux/rcupdate.h:647:9: warning: context imbalance in
'propagate_exception' - unexpected unlock

Fixes: d591fb56618f ("device_cgroup: simplify cgroup tree walk in propagate_exception()")
Cc: stable@vger.kernel.org
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

docs: fix broken references with multiple hints

The script:
./scripts/documentation-file-ref-check --fix

Gives multiple hints for broken references on some files.
Manually use the one that applies for some files.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>

device_cgroup: prepare code for bpf-based device controller

This is non-functional change to prepare the device cgroup code
for adding eBPF-based controller for cgroups v2.

The patch performs the following changes:
1) __devcgroup_inode_permission() and devcgroup_inode_mknod()
are moving to the device-cgroup.h and converting into static inline.
2) __devcgroup_check_permission() is exported.
3) devcgroup_check_permission() wrapper is introduced to be used
by both existing and new bpf-based implementations.

Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

device_cgroup: add DEVCG_ prefix to ACC_* and DEV_* constants

Rename device type and access type constants defined in
security/device_cgroup.c by adding the DEVCG_ prefix.

The reason behind this renaming is to make them global namespace
friendly, as they will be moved to the corresponding header file
by following patches.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

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>

security/device_cgroup: Fix RCU_LOCKDEP_WARN() condition

f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()")
introduced a bug by incorrectly inverting the condition when moving from
rcu_lockdep_assert() to RCU_LOCKDEP_WARN(). This commit therefore fixes
the inversion.

Reported-by: Felipe Balbi <balbi@ti.com>
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Tested-by: Josh Boyer <jwboyer@fedoraproject.org>

rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()

This commit renames rcu_lockdep_assert() to RCU_LOCKDEP_WARN() for
consistency with the WARN() series of macros. This also requires
inverting the sense of the conditional, which this commit also does.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>

cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes

Currently, cgroup_subsys->base_cftypes is used for both the unified
default hierarchy and legacy ones and subsystems can mark each file
with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE if it has to appear
only on one of them. This is quite hairy and error-prone. Also, we
may end up exposing interface files to the default hierarchy without
thinking it through.

cgroup_subsys will grow two separate cftype arrays and apply each only
on the hierarchies of the matching type. This will allow organizing
cftypes in a lot clearer way and encourage subsystems to scrutinize
the interface which is being exposed in the new default hierarchy.

In preparation, this patch renames cgroup_subsys->base_cftypes to
cgroup_subsys->legacy_cftypes. This patch is pure rename.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

device_cgroup: use css_has_online_children() instead of has_children()

devcgroup_update_access() wants to know whether there are child
cgroups which are online and visible to userland and has_children()
may return false positive. Replace it with css_has_online_children().

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Li Zefan <lizefan@huawei.com>

device_cgroup: remove direct access to cgroup->children

Currently, devcg::has_children() directly tests cgroup->children for
list emptiness. The field is not a published field and scheduled to
go away. In addition, the test isn't strictly correct as devcg should
only care about children which are visible to userland.

This patch converts has_children() to use css_next_child() instead.
The subtle incorrectness is noted and will be dealt with later.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Li Zefan <lizefan@huawei.com>

cgroup: remove css_parent()

cgroup in general is moving towards using cgroup_subsys_state as the
fundamental structural component and css_parent() was introduced to
convert from using cgroup->parent to css->parent. It was quite some
time ago and we're moving forward with making css more prominent.

This patch drops the trivial wrapper css_parent() and let the users
dereference css->parent. While at it, explicitly mark fields of css
which are public and immutable.

v2: New usage from device_cgroup.c converted.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: "David S. Miller" <davem@davemloft.net>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Johannes Weiner <hannes@cmpxchg.org>

cgroup: replace cftype->write_string() with cftype->write()

Convert all cftype->write_string() users to the new cftype->write()
which maps directly to kernfs write operation and has full access to
kernfs and cgroup contexts. The conversions are mostly mechanical.

* @css and @cft are accessed using of_css() and of_cft() accessors
respectively instead of being specified as arguments.

* Should return @nbytes on success instead of 0.

* @buf is not trimmed automatically. Trim if necessary. Note that
blkcg and netprio don't need this as the parsers already handle
whitespaces.

cftype->write_string() has no user left after the conversions and
removed.

While at it, remove unnecessary local variable @p in
cgroup_subtree_control_write() and stale comment about
CGROUP_LOCAL_BUFFER_SIZE in cgroup_freezer.c.

This patch doesn't introduce any visible behavior changes.

v2: netprio was missing from conversion. Converted.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: "David S. Miller" <davem@davemloft.net>

device_cgroup: check if exception removal is allowed

[PATCH v3 1/2] device_cgroup: check if exception removal is allowed

When the device cgroup hierarchy was introduced in
bd2953ebbb53 - devcg: propagate local changes down the hierarchy

a specific case was overlooked. Consider the hierarchy bellow:

A default policy: ALLOW, exceptions will deny access
\
B default policy: ALLOW, exceptions will deny access

There's no need to verify when an new exception is added to B because
in this case exceptions will deny access to further devices, which is
always fine. Hierarchy in device cgroup only makes sure B won't have
more access than A.

But when an exception is removed (by writing devices.allow), it isn't
checked if the user is in fact removing an inherited exception from A,
thus giving more access to B.

Example:

# echo 'a' >A/devices.allow
# echo 'c 1:3 rw' >A/devices.deny
# echo $$ >A/B/tasks
# echo >/dev/null
-bash: /dev/null: Operation not permitted
# echo 'c 1:3 w' >A/B/devices.allow
# echo >/dev/null
#

This shouldn't be allowed and this patch fixes it by making sure to never allow
exceptions in this case to be removed if the exception is partially or fully
present on the parent.

v3: missing '*' in function description
v2: improved log message and formatting fixes

Cc: cgroups@vger.kernel.org
Cc: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

device_cgroup: fix the comment format for recently added functions

Moving more extensive explanations to the end of the comment.

Cc: Li Zefan <lizefan@huawei.com>
Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

device_cgroup: rework device access check and exception checking

Whenever a device file is opened and checked against current device
cgroup rules, it uses the same function (may_access()) as when a new
exception rule is added by writing devices.{allow,deny}. And in both
cases, the algorithm is the same, doesn't matter the behavior.

First problem is having device access to be considered the same as rule
checking. Consider the following structure:

A (default behavior: allow, exceptions disallow access)
\
B (default behavior: allow, exceptions disallow access)

A new exception is added to B by writing devices.deny:

c 12:34 rw

When checking if that exception is allowed in may_access():

if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) {
if (behavior == DEVCG_DEFAULT_ALLOW) {
/* the exception will deny access to certain devices */
return true;

Which is ok, since B is not getting more privileges than A, it doesn't
matter and the rule is accepted

Now, consider it's a device file open check and the process belongs to
cgroup B. The access will be generated as:

behavior: allow
exception: c 12:34 rw

The very same chunk of code will allow it, even if there's an explicit
exception telling to do otherwise.

A simple test case:

# mkdir new_group
# cd new_group
# echo $$ >tasks
# echo "c 1:3 w" >devices.deny
# echo >/dev/null
# echo $?
0

This is a serious bug and was introduced on

c39a2a3018f8 devcg: prepare may_access() for hierarchy support

To solve this problem, the device file open function was split from the
new exception check.

Second problem is how exceptions are processed by may_access(). The
first part of the said function tries to match fully with an existing
exception:

list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) {
if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK))
continue;
if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR))
continue;
if (ex->major != ~0 && ex->major != refex->major)
continue;
if (ex->minor != ~0 && ex->minor != refex->minor)
continue;
if (refex->access & (~ex->access))
continue;
match = true;
break;
}

That means the new exception should be contained into an existing one to
be considered a match:

New exception Existing match? notes
b 12:34 rwm b 12:34 rwm yes
b 12:34 r b *:34 rw yes
b 12:34 rw b 12:34 w no extra "r"
b *:34 rw b 12:34 rw no too broad "*"
b *:34 rw b *:34 rwm yes

Which is fine in some cases. Consider:

A (default behavior: deny, exceptions allow access)
\
B (default behavior: deny, exceptions allow access)

In this case the full match makes sense, the new exception cannot add
more access than the parent allows

But this doesn't always work, consider:

A (default behavior: allow, exceptions disallow access)
\
B (default behavior: deny, exceptions allow access)

In this case, a new exception in B shouldn't match any of the exceptions
in A, after all you can't allow something that was forbidden by A. But
consider this scenario:

New exception Existing in A match? outcome
b 12:34 rw b 12:34 r no exception is accepted

Because the new exception has "w" as extra, it doesn't match, so it'll
be added to B's exception list.

The same problem can happen during a file access check. Consider a
cgroup with allow as default behavior:

Access Exception match?
b 12:34 rw b 12:34 r no

In this case, the access didn't match any of the exceptions in the
cgroup, which is required since exceptions will disallow access.

To solve this problem, two new functions were created to match an
exception either fully or partially. In the example above, a partial
check will be performed and it'll produce a match since at least
"b 12:34 r" from "b 12:34 rw" access matches.

Cc: cgroups@vger.kernel.org
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

cgroup: drop const from @buffer of cftype->write_string()

cftype->write_string() just passes on the writeable buffer from kernfs
and there's no reason to add const restriction on the buffer. The
only thing const achieves is unnecessarily complicating parsing of the
buffer. Drop const from @buffer.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

cgroup: clean up cgroup_subsys names and initialization

cgroup_subsys is a bit messier than it needs to be.

* The name of a subsys can be different from its internal identifier
defined in cgroup_subsys.h. Most subsystems use the matching name
but three - cpu, memory and perf_event - use different ones.

* cgroup_subsys_id enums are postfixed with _subsys_id and each
cgroup_subsys is postfixed with _subsys. cgroup.h is widely
included throughout various subsystems, it doesn't and shouldn't
have claim on such generic names which don't have any qualifier
indicating that they belong to cgroup.

* cgroup_subsys->subsys_id should always equal the matching
cgroup_subsys_id enum; however, we require each controller to
initialize it and then BUG if they don't match, which is a bit
silly.

This patch cleans up cgroup_subsys names and initialization by doing
the followings.

* cgroup_subsys_id enums are now postfixed with _cgrp_id, and each
cgroup_subsys with _cgrp_subsys.

* With the above, renaming subsys identifiers to match the userland
visible names doesn't cause any naming conflicts. All non-matching
identifiers are renamed to match the official names.

cpu_cgroup -> cpu
mem_cgroup -> memory
perf -> perf_event

* controllers no longer need to initialize ->subsys_id and ->name.
They're generated in cgroup core and set automatically during boot.

* Redundant cgroup_subsys declarations removed.

* While updating BUG_ON()s in cgroup_init_early(), convert them to
WARN()s. BUGging that early during boot is stupid - the kernel
can't print anything, even through serial console and the trap
handler doesn't even link stack frame properly for back-tracing.

This patch doesn't introduce any behavior changes.

v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs
classid handling into core").

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: "David S. Miller" <davem@davemloft.net>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Ingo Molnar <mingo@redhat.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Thomas Graf <tgraf@suug.ch>

cgroup: replace cftype->read_seq_string() with cftype->seq_show()

In preparation of conversion to kernfs, cgroup file handling is
updated so that it can be easily mapped to kernfs. This patch
replaces cftype->read_seq_string() with cftype->seq_show() which is
not limited to single_open() operation and will map directcly to
kernfs seq_file interface.

The conversions are mechanical. As ->seq_show() doesn't have @css and
@cft, the functions which make use of them are converted to use
seq_css() and seq_cft() respectively. In several occassions, e.f. if
it has seq_string in its name, the function name is updated to fit the
new method better.

This patch does not introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Neil Horman <nhorman@tuxdriver.com>

device_cgroup: remove can_attach

It is really only wanting to duplicate a check which is already done by the
cgroup subsystem.

With this patch, user jdoe still cannot move pid 1 into a devices cgroup
he owns, but now he can move his own other tasks into devices cgroups.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Aristeu Rozanski <aris@redhat.com>

cgroup: make css_for_each_descendant() and friends include the origin css in the iteration

Previously, all css descendant iterators didn't include the origin
(root of subtree) css in the iteration. The reasons were maintaining
consistency with css_for_each_child() and that at the time of
introduction more use cases needed skipping the origin anyway;
however, given that css_is_descendant() considers self to be a
descendant, omitting the origin css has become more confusing and
looking at the accumulated use cases rather clearly indicates that
including origin would result in simpler code overall.

While this is a change which can easily lead to subtle bugs, cgroup
API including the iterators has recently gone through major
restructuring and no out-of-tree changes will be applicable without
adjustments making this a relatively acceptable opportunity for this
type of change.

The conversions are mostly straight-forward. If the iteration block
had explicit origin handling before or after, it's moved inside the
iteration. If not, if (pos == origin) continue; is added. Some
conversions add extra reference get/put around origin handling by
consolidating origin handling and the rest. While the extra ref
operations aren't strictly necessary, this shouldn't cause any
noticeable difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>

cgroup: make hierarchy iterators deal with cgroup_subsys_state instead of cgroup

cgroup is currently in the process of transitioning to using css
(cgroup_subsys_state) as the primary handle instead of cgroup in
subsystem API. For hierarchy iterators, this is beneficial because

* In most cases, css is the only thing subsystems care about anyway.

* On the planned unified hierarchy, iterations for different
subsystems will need to skip over different subtrees of the
hierarchy depending on which subsystems are enabled on each cgroup.
Passing around css makes it unnecessary to explicitly specify the
subsystem in question as css is intersection between cgroup and
subsystem

* For the planned unified hierarchy, css's would need to be created
and destroyed dynamically independent from cgroup hierarchy. Having
cgroup core manage css iteration makes enforcing deref rules a lot
easier.

Most subsystem conversions are straight-forward. Noteworthy changes
are

* blkio: cgroup_to_blkcg() is no longer used. Removed.

* freezer: cgroup_freezer() is no longer used. Removed.

* devices: cgroup_to_devcgroup() is no longer used. Removed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>

cgroup: pass around cgroup_subsys_state instead of cgroup in file methods

cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup.
Please see the previous commit which converts the subsystem methods
for rationale.

This patch converts all cftype file operations to take @css instead of
@cgroup. cftypes for the cgroup core files don't have their subsytem
pointer set. These will automatically use the dummy_css added by the
previous patch and can be converted the same way.

Most subsystem conversions are straight forwards but there are some
interesting ones.

* freezer: update_if_frozen() is also converted to take @css instead
of @cgroup for consistency. This will make the code look simpler
too once iterators are converted to use css.

* memory/vmpressure: mem_cgroup_from_css() needs to be exported to
vmpressure while mem_cgroup_from_cont() can be made static.
Updated accordingly.

* cpu: cgroup_tg() doesn't have any user left. Removed.

* cpuacct: cgroup_ca() doesn't have any user left. Removed.

* hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left.
Removed.

* net_cls: cgrp_cls_state() doesn't have any user left. Removed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>

cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods

cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup *
in subsystem implementations for the following reasons.

* With unified hierarchy, subsystems will be dynamically bound and
unbound from cgroups and thus css's (cgroup_subsys_state) may be
created and destroyed dynamically over the lifetime of a cgroup,
which is different from the current state where all css's are
allocated and destroyed together with the associated cgroup. This
in turn means that cgroup_css() should be synchronized and may
return NULL, making it more cumbersome to use.

* Differing levels of per-subsystem granularity in the unified
hierarchy means that the task and descendant iterators should behave
differently depending on the specific subsystem the iteration is
being performed for.

* In majority of the cases, subsystems only care about its part in the
cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods
often obtain the matching css pointer from the cgroup and don't
bother with the cgroup pointer itself. Passing around css fits
much better.

This patch converts all cgroup_subsys methods to take @css instead of
@cgroup. The conversions are mostly straight-forward. A few
noteworthy changes are

* ->css_alloc() now takes css of the parent cgroup rather than the
pointer to the new cgroup as the css for the new cgroup doesn't
exist yet. Knowing the parent css is enough for all the existing
subsystems.

* In kernel/cgroup.c::offline_css(), unnecessary open coded css
dereference is replaced with local variable access.

This patch shouldn't cause any behavior differences.

v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced
with local variable @css as suggested by Li Zefan.

Rebased on top of new for-3.12 which includes for-3.11-fixes so
that ->css_free() invocation added by da0a12caff ("cgroup: fix a
leak when percpu_ref_init() fails") is converted too. Suggested
by Li Zefan.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>

cgroup: add css_parent()

Currently, controllers have to explicitly follow the cgroup hierarchy
to find the parent of a given css. cgroup is moving towards using
cgroup_subsys_state as the main controller interface construct, so
let's provide a way to climb the hierarchy using just csses.

This patch implements css_parent() which, given a css, returns its
parent. The function is guarnateed to valid non-NULL parent css as
long as the target css is not at the top of the hierarchy.

freezer, cpuset, cpu, cpuacct, hugetlb, memory, net_cls and devices
are converted to use css_parent() instead of accessing cgroup->parent
directly.

* __parent_ca() is dropped from cpuacct and its usage is replaced with
parent_ca(). The only difference between the two was NULL test on
cgroup->parent which is now embedded in css_parent() making the
distinction moot. Note that eventually a css->parent field will be
added to css and the NULL check in css_parent() will go away.

This patch shouldn't cause any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

cgroup: add/update accessors which obtain subsys specific data from css

css (cgroup_subsys_state) is usually embedded in a subsys specific
data structure. Subsystems either use container_of() directly to cast
from css to such data structure or has an accessor function wrapping
such cast. As cgroup as whole is moving towards using css as the main
interface handle, add and update such accessors to ease dealing with
css's.

All accessors explicitly handle NULL input and return NULL in those
cases. While this looks like an extra branch in the code, as all
controllers specific data structures have css as the first field, the
casting doesn't involve any offsetting and the compiler can trivially
optimize out the branch.

* blkio, freezer, cpuset, cpu, cpuacct and net_cls didn't have such
accessor. Added.

* memory, hugetlb and devices already had one but didn't explicitly
handle NULL input. Updated.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

cgroup: s/cgroup_subsys_state/cgroup_css/ s/task_subsys_state/task_css/

The names of the two struct cgroup_subsys_state accessors -
cgroup_subsys_state() and task_subsys_state() - are somewhat awkward.
The former clashes with the type name and the latter doesn't even
indicate it's somehow related to cgroup.

We're about to revamp large portion of cgroup API, so, let's rename
them so that they're less awkward. Most per-controller usages of the
accessors are localized in accessor wrappers and given the amount of
scheduled changes, this isn't gonna add any noticeable headache.

Rename cgroup_subsys_state() to cgroup_css() and task_subsys_state()
to task_css(). This patch is pure rename.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

device_cgroup: simplify cgroup tree walk in propagate_exception()

During a config change, propagate_exception() needs to traverse the
subtree to update config on the subtree. Because such config updates
need to allocate memory, it couldn't directly use
cgroup_for_each_descendant_pre() which required the whole iteration to
be contained in a single RCU read critical section. To work around
the limitation, propagate_exception() built a linked list of
descendant cgroups while read-locking RCU and then walked the list
afterwards, which is safe as the whole iteration is protected by
devcgroup_mutex. This works but is cumbersome.

With the recent updates, cgroup iterators now allow dropping RCU read
lock while iteration is in progress making this workaround no longer
necessary. This patch replaces dev_cgroup->propagate_pending list and
get_online_devcg() with direct cgroup_for_each_descendant_pre() walk.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Aristeu Rozanski <aris@redhat.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>

devcg: remove parent_cgroup.

In devcgroup_css_alloc(), there is no longer need for parent_cgroup.
bd2953ebbb("devcg: propagate local changes down the hierarchy") made
the variable parent_cgroup redundant. This patch removes parent_cgroup
from devcgroup_css_alloc().

Signed-off-by: Rami Rosen <ramirose@gmail.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

devcg: remove broken_hierarchy tag

bd2953ebbb ("devcg: propagate local changes down the hierarchy")
implemented proper hierarchy support. Remove the broken tag.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <aris@redhat.com>

devcg: propagate local changes down the hierarchy

This patch makes exception changes to propagate down in hierarchy respecting
when possible local exceptions.

New exceptions allowing additional access to devices won't be propagated, but
it'll be possible to add an exception to access all of part of the newly
allowed device(s).

New exceptions disallowing access to devices will be propagated down and the
local group's exceptions will be revalidated for the new situation.
Example:
A
/ \
B

group behavior exceptions
A allow "b 8:* rwm", "c 116:1 rw"
B deny "c 1:3 rwm", "c 116:2 rwm", "b 3:* rwm"

If a new exception is added to group A:
# echo "c 116:* r" > A/devices.deny
it'll propagate down and after revalidating B's local exceptions, the exception
"c 116:2 rwm" will be removed.

In case parent's exceptions change and local exceptions are not allowed anymore,
they'll be deleted.

v7:
- do not allow behavior change when the cgroup has children
- update documentation

v6: fixed issues pointed by Serge Hallyn
- only copy parent's exceptions while propagating behavior if the local
behavior is different
- while propagating exceptions, do not clear and copy parent's: it'd be against
the premise we don't propagate access to more devices

v5: fixed issues pointed by Serge Hallyn
- updated documentation
- not propagating when an exception is written to devices.allow
- when propagating a new behavior, clean the local exceptions list if they're
for a different behavior

v4: fixed issues pointed by Tejun Heo
- separated function to walk the tree and collect valid propagation targets

v3: fixed issues pointed by Tejun Heo
- update documentation
- move css_online/css_offline changes to a new patch
- use cgroup_for_each_descendant_pre() instead of own descendant walk
- move exception_copy rework to a separared patch
- move exception_clean rework to a separated patch

v2: fixed issues pointed by Tejun Heo
- instead of keeping the local settings that won't apply anymore, remove them

Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

devcg: use css_online and css_offline

Allocate resources and change behavior only when online. This is needed in
order to determine if a node is suitable for hierarchy propagation or if it's
being removed.

Locking:
Both functions take devcgroup_mutex to make changes to device_cgroup structure.
Hierarchy propagation will also take devcgroup_mutex before walking the
tree while walking the tree itself is protected by rcu lock.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

devcg: prepare may_access() for hierarchy support

Currently may_access() is only able to verify if an exception is valid for the
current cgroup, which has the same behavior. With hierarchy, it'll be also used
to verify if a cgroup local exception is valid towards its cgroup parent, which
might have different behavior.

v2:
- updated patch description
- rebased on top of a new patch to expand the may_access() logic to make it
more clear
- fixed argument description order in may_access()

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

devcg: expand may_access() logic

In order to make the next patch more clear, expand may_access() logic.

v2: may_access() returns bool now

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

device_cgroup: don't grab mutex in rcu callback

Commit 103a197c0c4e ("security/device_cgroup: lock assert fails in
dev_exception_clean()") grabs devcgroup_mutex to fix assert failure, but
a mutex can't be grabbed in rcu callback. Since there shouldn't be any
other references when css_free is called, mutex isn't needed for list
cleanup in devcgroup_css_free().

Signed-off-by: Jerry Snitselaar <jerry.snitselaar@oracle.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

security/device_cgroup: lock assert fails in dev_exception_clean()

devcgroup_css_free() calls dev_exception_clean() without the devcgroup_mutex being locked.

Shutting down a kvm virt was giving me the following trace:

[36280.732764] ------------[ cut here ]------------
[36280.732778] WARNING: at /home/snits/dev/linux/security/device_cgroup.c:172 dev_exception_clean+0xa9/0xc0()
[36280.732782] Hardware name: Studio XPS 8100
[36280.732785] Modules linked in: xt_REDIRECT fuse ebtable_nat ebtables ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat xt_CHECKSUM iptable_mangle bridge stp llc nf_conntrack_ipv4 ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 nf_defrag_ipv4 ip6table_filter it87 hwmon_vid xt_state nf_conntrack ip6_tables snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq coretemp snd_seq_device crc32c_intel snd_pcm snd_page_alloc snd_timer snd broadcom tg3 serio_raw i7core_edac edac_core ptp pps_core lpc_ich pcspkr mfd_core soundcore microcode i2c_i801 nfsd auth_rpcgss nfs_acl lockd vhost_net sunrpc tun macvtap macvlan kvm_intel kvm uinput binfmt_misc autofs4 usb_storage firewire_ohci firewire_core crc_itu_t radeon drm_kms_helper ttm
[36280.732921] Pid: 933, comm: libvirtd Tainted: G W 3.8.0-rc3-00307-g4c217de #1
[36280.732922] Call Trace:
[36280.732927] [<ffffffff81044303>] warn_slowpath_common+0x93/0xc0
[36280.732930] [<ffffffff8104434a>] warn_slowpath_null+0x1a/0x20
[36280.732932] [<ffffffff812deaf9>] dev_exception_clean+0xa9/0xc0
[36280.732934] [<ffffffff812deb2a>] devcgroup_css_free+0x1a/0x30
[36280.732938] [<ffffffff810ccd76>] cgroup_diput+0x76/0x210
[36280.732941] [<ffffffff8119eac0>] d_delete+0x120/0x180
[36280.732943] [<ffffffff81195cff>] vfs_rmdir+0xef/0x130
[36280.732945] [<ffffffff81195e47>] do_rmdir+0x107/0x1c0
[36280.732949] [<ffffffff8132d17e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[36280.732951] [<ffffffff81198646>] sys_rmdir+0x16/0x20
[36280.732954] [<ffffffff8173bd82>] system_call_fastpath+0x16/0x1b
[36280.732956] ---[ end trace ca39dced899a7d9f ]---

Signed-off-by: Jerry Snitselaar <jerry.snitselaar@oracle.com>
Cc: stable@kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>

cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offline/free()

Rename cgroup_subsys css lifetime related callbacks to better describe
what their roles are. Also, update documentation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

device_cgroup: add lockdep asserts

device_cgroup uses RCU safe ->exceptions list which is write-protected
by devcgroup_mutex and has had some issues using locking correctly.
Add lockdep asserts to utility functions so that future errors can be
easily detected.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>

device_cgroup: fix RCU usage

dev_cgroup->exceptions is protected with devcgroup_mutex for writes
and RCU for reads; however, RCU usage isn't correct.

* dev_exception_clean() doesn't use RCU variant of list_del() and
kfree(). The function can race with may_access() and may_access()
may end up dereferencing already freed memory. Use list_del_rcu()
and kfree_rcu() instead.

* may_access() may be called only with RCU read locked but doesn't use
RCU safe traversal over ->exceptions. Use list_for_each_entry_rcu().

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Cc: stable@vger.kernel.org
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>

device_cgroup: fix unchecked cgroup parent usage

In 4cef7299b478687 ("device_cgroup: add proper checking when changing
default behavior") the cgroup parent usage is unchecked. root will not
have a parent and trying to use device.{allow,deny} will cause problems.
For some reason my stressing scripts didn't test the root directory so I
didn't catch it on my regular tests.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

device_cgroup: add proper checking when changing default behavior

Before changing a group's default behavior to ALLOW, we must check if
its parent's behavior is also ALLOW.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

device_cgroup: stop using simple_strtoul()

Convert the code to use kstrtou32() instead of simple_strtoul() which is
deprecated. The real size of the variables are u32, so use kstrtou32
instead of kstrtoul

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

device_cgroup: rename deny_all to behavior

This was done in a v2 patch but v1 ended up being committed. The
variable name is less confusing and stores the default behavior when no
matching exception exists.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

cgroup: fix invalid rcu dereference

Commit ad676077a2ae ("device_cgroup: convert device_cgroup internally to
policy + exceptions") removed rcu locks which are needed in
task_devcgroup called in this chain:

devcgroup_inode_mknod OR __devcgroup_inode_permission ->
__devcgroup_inode_permission ->
task_devcgroup ->
task_subsys_state ->
task_subsys_state_check.

Change the code so that task_devcgroup is safely called with rcu read
lock held.

===============================
[ INFO: suspicious RCU usage. ]
3.6.0-rc5-next-20120913+ #42 Not tainted
-------------------------------
include/linux/cgroup.h:553 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
2 locks held by kdevtmpfs/23:
#0: (sb_writers){.+.+.+}, at: [<ffffffff8116873f>]
mnt_want_write+0x1f/0x50
#1: (&sb->s_type->i_mutex_key#3/1){+.+.+.}, at: [<ffffffff811558af>]
kern_path_create+0x7f/0x170

stack backtrace:
Pid: 23, comm: kdevtmpfs Not tainted 3.6.0-rc5-next-20120913+ #42
Call Trace:
lockdep_rcu_suspicious+0xfd/0x130
devcgroup_inode_mknod+0x19d/0x240
vfs_mknod+0x71/0xf0
handle_create.isra.2+0x72/0x200
devtmpfsd+0x114/0x140
? handle_create.isra.2+0x200/0x200
kthread+0xd6/0xe0
kernel_thread_helper+0x4/0x10

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Dave Jones <davej@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

device_cgroup: rename whitelist to exception list

This patch replaces the "whitelist" usage in the code and comments and replace
them by exception list related information.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

device_cgroup: convert device_cgroup internally to policy + exceptions

The original model of device_cgroup is having a whitelist where all the
allowed devices are listed. The problem with this approach is that is
impossible to have the case of allowing everything but few devices.

The reason for that lies in the way the whitelist is handled internally:
since there's only a whitelist, the "all devices" entry would have to be
removed and replaced by the entire list of possible devices but the ones
that are being denied. Since dev_t is 32 bits long, representing the allowed
devices as a bitfield is not memory efficient.

This patch replaces the "whitelist" by a "exceptions" list and the default
policy is kept as "deny_all" variable in dev_cgroup structure.

The current interface determines that whenever "a" is written to devices.allow
or devices.deny, the entry masking all devices will be added or removed,
respectively. This behavior is kept and it's what will determine the default
policy:

# cat devices.list
a *:* rwm
# echo a >devices.deny
# cat devices.list
# echo a >devices.allow
# cat devices.list
a *:* rwm

The interface is also preserved. For example, if one wants to block only access
to /dev/null:
# ls -l /dev/null
crw-rw-rw- 1 root root 1, 3 Jul 24 16:17 /dev/null
# echo a >devices.allow
# echo "c 1:3 rwm" >devices.deny
# cat /dev/null
cat: /dev/null: Operation not permitted
# echo >/dev/null
bash: /dev/null: Operation not permitted
mknod /tmp/null c 1 3
mknod: `/tmp/null': Operation not permitted
# echo "c 1:3 r" >devices.allow
# cat /dev/null
# echo >/dev/null
bash: /dev/null: Operation not permitted
mknod /tmp/null c 1 3
mknod: `/tmp/null': Operation not permitted
# echo "c 1:3 rw" >devices.allow
# echo >/dev/null
# cat /dev/null
# mknod /tmp/null c 1 3
mknod: `/tmp/null': Operation not permitted
# echo "c 1:3 rwm" >devices.allow
# echo >/dev/null
# cat /dev/null
# mknod /tmp/null c 1 3
#

Note that I didn't rename the functions/variables in this patch, but in the
next one to make reviewing easier.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

device_cgroup: introduce dev_whitelist_clean()

This function cleans all the items in a whitelist and will be used by the next
patches.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

device_cgroup: add "deny_all" in dev_cgroup structure

deny_all will determine if the default policy is to deny all device access
unless for the ones in the exception list.

This variable will be used in the next patches to convert device_cgroup
internally into a default policy + rules.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them

Currently, cgroup hierarchy support is a mess. cpu related subsystems
behave correctly - configuration, accounting and control on a parent
properly cover its children. blkio and freezer completely ignore
hierarchy and treat all cgroups as if they're directly under the root
cgroup. Others show yet different behaviors.

These differing interpretations of cgroup hierarchy make using cgroup
confusing and it impossible to co-mount controllers into the same
hierarchy and obtain sane behavior.

Eventually, we want full hierarchy support from all subsystems and
probably a unified hierarchy. Users using separate hierarchies
expecting completely different behaviors depending on the mounted
subsystem is deterimental to making any progress on this front.

This patch adds cgroup_subsys.broken_hierarchy and sets it to %true
for controllers which are lacking in hierarchy support. The goal of
this patch is two-fold.

* Move users away from using hierarchy on currently non-hierarchical
subsystems, so that implementing proper hierarchy support on those
doesn't surprise them.

* Keep track of which controllers are broken how and nudge the
subsystems to implement proper hierarchy support.

For now, start with a single warning message. We can whine louder
later on.

v2: Fixed a typo spotted by Michal. Warning message updated.

v3: Updated memcg part so that it doesn't generate warning in the
cases where .use_hierarchy=false doesn't make the behavior
different from root.use_hierarchy=true. Fixed a typo spotted by
Glauber.

v4: Check ->broken_hierarchy after cgroup creation is complete so that
->create() can affect the result per Michal. Dropped unnecessary
memcg root handling per Michal.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

cgroup: convert all non-memcg controllers to the new cftype interface

Convert debug, freezer, cpuset, cpu_cgroup, cpuacct, net_prio, blkio,
net_cls and device controllers to use the new cftype based interface.
Termination entry is added to cftype arrays and populate callbacks are
replaced with cgroup_subsys->base_cftypes initializations.

This is functionally identical transformation. There shouldn't be any
visible behavior change.

memcg is rather special and will be converted separately.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Vivek Goyal <vgoyal@redhat.com>

cgroup: remove cgroup_subsys argument from callbacks

The argument is not used at all, and it's not necessary, because
a specific callback handler of course knows which subsys it
belongs to.

Now only ->pupulate() takes this argument, because the handlers of
this callback always call cgroup_add_file()/cgroup_add_files().

So we reduce a few lines of code, though the shrinking of object size
is minimal.

16 files changed, 113 insertions(+), 162 deletions(-)

text data bss dec hex filename
5486240 656987 7039960 13183187 c928d3 vmlinux.o.orig
5486170 656987 7039960 13183117 c9288d vmlinux.o

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach()

Currently, there's no way to pass multiple tasks to cgroup_subsys
methods necessitating the need for separate per-process and per-task
methods. This patch introduces cgroup_taskset which can be used to
pass multiple tasks and their associated cgroups to cgroup_subsys
methods.

Three methods - can_attach(), cancel_attach() and attach() - are
converted to use cgroup_taskset. This unifies passed parameters so
that all methods have access to all information. Conversions in this
patchset are identical and don't introduce any behavior change.

-v2: documentation updated as per Paul Menage's suggestion.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Paul Menage <paul@paulmenage.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: James Morris <jmorris@namei.org>

security,rcu: Convert call_rcu(whitelist_item_free) to kfree_rcu()

The rcu callback whitelist_item_free() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(whitelist_item_free).

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: James Morris <jmorris@namei.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

devcgroup_inode_permission: take "is it a device node" checks to inlined wrapper

inode_permission() calls devcgroup_inode_permission() and almost all such
calls are _not_ for device nodes; let's at least keep the common path
straight...

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

cgroups: add per-thread subsystem callbacks

Add cgroup subsystem callbacks for per-thread attachment in atomic contexts

Add can_attach_task(), pre_attach(), and attach_task() as new callbacks
for cgroups's subsystem interface. Unlike can_attach and attach, these
are for per-thread operations, to be called potentially many times when
attaching an entire threadgroup.

Also, the old "bool threadgroup" interface is removed, as replaced by
this. All subsystems are modified for the new interface - of note is
cpuset, which requires from/to nodemasks for attach to be globally scoped
(though per-cpuset would work too) to persist from its pre_attach to
attach_task and attach.

This is a pre-patch for cgroup-procs-writable.patch.

Signed-off-by: Ben Blum <bblum@andrew.cmu.edu>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Reviewed-by: Paul Menage <menage@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

security: whitespace coding style fixes

Whitespace coding style fixes.

Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: James Morris <jmorris@namei.org>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.

2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).

* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time

Alter the ss->can_attach and ss->attach functions to be able to deal with
a whole threadgroup at a time, for use in cgroup_attach_proc. (This is a
pre-patch to cgroup-procs-writable.patch.)

Currently, new mode of the attach function can only tell the subsystem
about the old cgroup of the threadgroup leader. No subsystem currently
needs that information for each thread that's being moved, but if one were
to be added (for example, one that counts tasks within a group) this bit
would need to be reworked a bit to tell the subsystem the right
information.

[hidave.darkstar@gmail.com: fix build]
Signed-off-by: Ben Blum <bblum@google.com>
Signed-off-by: Paul Menage <menage@google.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Reviewed-by: Matt Helsley <matthltc@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: skip superfluous checks when found the DEV_ALL elem

While walking through the whitelist, if the DEV_ALL item is found, no more
check is needed.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: avoid using cgroup_lock

There is nothing special that has to be protected by cgroup_lock,
so introduce devcgroup_mtuex for it's own use.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.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>

devices cgroup: allow mkfifo

The devcgroup_inode_permission() hook in the devices whitelist cgroup has
always bypassed access checks on fifos. But the mknod hook did not. The
devices whitelist is only about block and char devices, and fifos can't
even be added to the whitelist, so fifos can't be created at all except by
tasks which have 'a' in their whitelist (meaning they have access to all
devices).

Fix the behavior by bypassing access checks to mkfifo.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: James Morris <jmorris@namei.org>
Reported-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Cc: <stable@kernel.org> [2.6.27.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: use list_for_each_entry_rcu()

We should use list_for_each_entry_rcu in RCU read site.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: remove spin_lock()

Since we introduced rcu for read side, spin_lock is used only for update.
But we always hold cgroup_lock() when update, so spin_lock() is not need.

Additional cleanup:
1) include linux/rcupdate.h explicitly
2) remove unused variable cur_devcgroup in devcgroup_update_access()

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: "Serge E. Hallyn" <serue@us.ibm.com>
Cc: Paul Menage <menage@google.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>

devcgroup: remove unused variable

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: use kmemdup()

This saves 40 bytes on my x86_32 box.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: fix race against rmdir()

During the use of a dev_cgroup, we should guarantee the corresponding
cgroup won't be deleted (i.e. via rmdir). This can be done through
css_get(&dev_cgroup->css), but here we can just get and use the dev_cgroup
under rcu_read_lock.

And also remove checking NULL dev_cgroup, it won't be NULL since a task
always belongs to a cgroup.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: code cleanup

- clean up set_majmin()
- use simple_strtoul() to parse major/minor

[akpm@linux-foundation.org: fix simple_strtoul() usage]
[kosaki.motohiro@jp.fujitsu.com: fix warnings]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-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>

devcgroup: relax white-list protection down to RCU

Currently this list is protected with a simple spinlock, even for reading
from one. This is OK, but can be better.

Actually I want it to be better very much, since after replacing the
OpenVZ device permissions engine with the cgroup-based one I noticed, that
we set 12 default device permissions for each newly created container (for
/dev/null, full, terminals, ect devices), and people sometimes have up to
20 perms more, so traversing the ~30-40 elements list under a spinlock
doesn't seem very good.

Here's the RCU protection for white-list - dev_whitelist_item-s are added
and removed under the devcg->lock, but are looked up in permissions
checking under the rcu_read_lock.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

cgroup files: convert devcgroup_access_write() into a cgroup write_string() handler

This patch converts devcgroup_access_write() from a raw file handler
into a handler for the cgroup write_string() method. This allows some
boilerplate copying/locking/checking to be removed and simplifies the
cleanup path, since these functions are performed by the cgroups
framework before calling the handler.

Signed-off-by: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.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>

devcgroup: fix permission check when adding entry to child cgroup

# cat devices.list
c 1:3 r
# echo 'c 1:3 w' > sub/devices.allow
# cat sub/devices.list
c 1:3 w

As illustrated, the parent group has no write permission to /dev/null, so
it's child should not be allowed to add this write permission.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: always show positive major/minor num

# echo "b $((0x7fffffff)):$((0x80000000)) rwm" > devices.allow
# cat devices.list
b 214748364:-21474836 rwm

though a major/minor number of 0x800000000 is meaningless, we
should not cast it to a negative value.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: fix odd behaviour when writing 'a' to devices.allow

# cat /devcg/devices.list
a *:* rwm
# echo a > devices.allow
# cat /devcg/devices.list
a *:* rwm
a 0:0 rwm

This is odd and maybe confusing. With this patch, writing 'a' to
devices.allow will add 'a *:* rwm' to the whitelist.

Also a few fixes and updates to the document.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
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>

devscgroup: make white list more compact in some cases

Consider you added a 'c foo:bar r' permission to some cgroup and then (a
bit later) 'c'foo:bar w' for it. After this you'll see the

c foo:bar r
c foo:bar w

lines in a devices.list file.

Another example - consider you added 10 'c foo:bar r' permissions to some
cgroup (e.g. by mistake). After this you'll see 10 c foo:bar r lines in
a list file.

This is weird. This situation also has one more annoying consequence.
Having many items in a white list makes permissions checking slower, sine
it has to walk a longer list.

The proposal is to merge permissions for items, that correspond to the
same device.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devscgroup: relax task to dev_cgroup conversion

Two functions, that need to get a device_cgroup from a task (they are
devcgroup_inode_permission and devcgroup_inode_mknod) make it in a strange
way:

They get a css_set from task, then a subsys_state from css_set, then a
cgroup from the state and then a subsys_state again from the cgroup.
Besides, the devices_subsys_id is read from memory, whilst there's a
enum-ed constant for it.

Optimize this part a bit:
1. Get the subsys_stats form the task and be done - no 2 extra
dereferences,
2. Use the device_subsys_id constant, not the value from memory
(i.e. one less dereference).

Found while preparing 2.6.26 OpenVZ port.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devcgroup: make a helper to convert cgroup_subsys_state to devs_cgroup

This is just picking the container_of out of cgroup_to_devcgroup into a
separate function.

This new css_to_devcgroup will be used in the 2nd patch.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

cgroups: introduce cft->read_seq()

Introduce a read_seq() helper in cftype, which uses seq_file to print out
lists. Use it in the devices cgroup. Also split devices.allow into two
files, so now devices.deny and devices.allow are the ones to use to manipulate
the whitelist, while devices.list outputs the cgroup's current whitelist.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Acked-by: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.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>

cgroups: implement device whitelist

Implement a cgroup to track and enforce open and mknod restrictions on device
files. A device cgroup associates a device access whitelist with each cgroup.
A whitelist entry has 4 fields. 'type' is a (all), c (char), or b (block).
'all' means it applies to all types and all major and minor numbers. Major
and minor are either an integer or * for all. Access is a composition of r
(read), w (write), and m (mknod).

The root device cgroup starts with rwm to 'all'. A child devcg gets a copy of
the parent. Admins can then remove devices from the whitelist or add new
entries. A child cgroup can never receive a device access which is denied its
parent. However when a device access is removed from a parent it will not
also be removed from the child(ren).

An entry is added using devices.allow, and removed using
devices.deny. For instance

echo 'c 1:3 mr' > /cgroups/1/devices.allow

allows cgroup 1 to read and mknod the device usually known as
/dev/null. Doing

echo a > /cgroups/1/devices.deny

will remove the default 'a *:* mrw' entry.

CAP_SYS_ADMIN is needed to change permissions or move another task to a new
cgroup. A cgroup may not be granted more permissions than the cgroup's parent
has. Any task can move itself between cgroups. This won't be sufficient, but
we can decide the best way to adequately restrict movement later.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix may-be-used-uninitialized warning]
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Acked-by: James Morris <jmorris@namei.org>
Looks-good-to: Pavel Emelyanov <xemul@openvz.org>
Cc: Daniel Hokka Zakrisson <daniel@hozac.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.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>