fs: Remove the now superfluous sentinel elements from ctl_table array

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel elements ctl_table struct. Special attention was placed in
making sure that an empty directory for fs/verity was created when
CONFIG_FS_VERITY_BUILTIN_SIGNATURES is not defined. In this case we use the
register sysctl call that expects a size.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

fanotify: allow "weak" fsid when watching a single filesystem

So far, fanotify returns -ENODEV or -EXDEV when trying to set a mark
on a filesystem with a "weak" fsid, namely, zero fsid (e.g. fuse), or
non-uniform fsid (e.g. btrfs non-root subvol).

When group is watching inodes all from the same filesystem (or subvol),
allow adding inode marks with "weak" fsid, because there is no ambiguity
regarding which filesystem reports the event.

The first mark added to a group determines if this group is single or
multi filesystem, depending on the fsid at the path of the added mark.

If the first mark added has a "strong" fsid, marks with "weak" fsid
cannot be added and vice versa.

If the first mark added has a "weak" fsid, following marks must have
the same "weak" fsid and the same sb as the first mark.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20231130165619.3386452-3-amir73il@gmail.com>

fanotify: store fsid in mark instead of in connector

Some filesystems like fuse and nfs have zero or non-unique fsid.
We would like to avoid reporting ambiguous fsid in events, so we need
to avoid marking objects with same fsid and different sb.

To make this easier to enforce, store the fsid in the marks of the group
instead of in the shared conenctor.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20231130165619.3386452-2-amir73il@gmail.com>

exportfs: add helpers to check if filesystem can encode/decode file handles

The logic of whether filesystem can encode/decode file handles is open
coded in many places.

In preparation to changing the logic, move the open coded logic into
inline helpers.

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231023180801.2953446-2-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

treewide: mark stuff as __ro_after_init

__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "const" and "__init" while I'm at it.

[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fanotify: limit reporting of event with non-decodeable file handles

Commit a95aef69a740 ("fanotify: support reporting non-decodeable file
handles") merged in v6.5-rc1, added the ability to use an fanotify group
with FAN_REPORT_FID mode to watch filesystems that do not support nfs
export, but do know how to encode non-decodeable file handles, with the
newly introduced AT_HANDLE_FID flag.

At the time that this commit was merged, there were no filesystems
in-tree with those traits.

Commit 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles"),
merged in v6.6-rc1, added this trait to overlayfs, thus allowing fanotify
watching of overlayfs with FAN_REPORT_FID mode.

In retrospect, allowing an fanotify filesystem/mount mark on such
filesystem in FAN_REPORT_FID mode will result in getting events with
file handles, without the ability to resolve the filesystem objects from
those file handles (i.e. no open_by_handle_at() support).

For v6.6, the safer option would be to allow this mode for inode marks
only, where the caller has the opportunity to use name_to_handle_at() at
the time of setting the mark. In the future we can revise this decision.

Fixes: a95aef69a740 ("fanotify: support reporting non-decodeable file handles")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20231018100000.2453965-2-amir73il@gmail.com>

fanotify: disallow mount/sb marks on kernel internal pseudo fs

Hopefully, nobody is trying to abuse mount/sb marks for watching all
anonymous pipes/inodes.

I cannot think of a good reason to allow this - it looks like an
oversight that dated back to the original fanotify API.

Link: https://lore.kernel.org/linux-fsdevel/20230628101132.kvchg544mczxv2pm@quack3/
Fixes: 0ff21db9fcc3 ("fanotify: hooks the fanotify_mark syscall to the vfsmount code")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230629042044.25723-1-amir73il@gmail.com>

fanotify: support reporting non-decodeable file handles

fanotify users do not always need to decode the file handles reported
with FAN_REPORT_FID.

Relax the restriction that filesystem needs to support NFS export and
allow reporting file handles from filesystems that only support ecoding
unique file handles.

Even filesystems that do not have export_operations at all can fallback
to use the default FILEID_INO32_GEN encoding, but we use the existence
of export_operations as an indication that the encoded file handles will
be sufficiently unique and that user will be able to compare them to
filesystem objects using AT_HANDLE_FID flag to name_to_handle_at(2).

For filesystems that do not support NFS export, users will have to use
the AT_HANDLE_FID of name_to_handle_at(2) if they want to compare the
object in path to the object fid reported in an event.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230502124817.3070545-5-amir73il@gmail.com>

fanotify: use pidfd_prepare()

We generally try to avoid installing a file descriptor into the caller's
file descriptor table just to close it again via close_fd() in case an
error occurs. Instead we reserve a file descriptor but don't install it
into the caller's file descriptor table yet. If we fail for other,
unrelated reasons we can just close the reserved file descriptor and if
we make it past all meaningful error paths we just install it. Fanotify
gets this right already for one fd type but not for pidfds.

Use the new pidfd_prepare() helper to reserve a pidfd and a pidfd file
and switch to the more common fd allocation and installation pattern.

Acked-by: Jan Kara <jack@suse.cz>
Message-Id: <20230327-pidfd-file-api-v1-3-5c0e9a3158e4@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fanotify: define struct members to hold response decision context

This patch adds a flag, FAN_INFO and an extensible buffer to provide
additional information about response decisions. The buffer contains
one or more headers defining the information type and the length of the
following information. The patch defines one additional information
type, FAN_RESPONSE_INFO_AUDIT_RULE, to audit a rule number. This will
allow for the creation of other information types in the future if other
users of the API identify different needs.

The kernel can be tested if it supports a given info type by supplying
the complete info extension but setting fd to FAN_NOFD. It will return
the expected size but not issue an audit record.

Suggested-by: Steve Grubb <sgrubb@redhat.com>
Link: https://lore.kernel.org/r/2745105.e9J7NaK4W3@x2
Suggested-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20201001101219.GE17860@quack2.suse.cz
Tested-by: Steve Grubb <sgrubb@redhat.com>
Acked-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <10177cfcae5480926b7176321a28d9da6835b667.1675373475.git.rgb@redhat.com>

fanotify: Ensure consistent variable type for response

The user space API for the response variable is __u32. This patch makes
sure that the whole path through the kernel uses u32 so that there is
no sign extension or truncation of the user space response.

Suggested-by: Steve Grubb <sgrubb@redhat.com>
Link: https://lore.kernel.org/r/12617626.uLZWGnKmhe@x2
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Tested-by: Steve Grubb <sgrubb@redhat.com>
Acked-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <3778cb0b3501bc4e686ba7770b20eb9ab0506cf4.1675373475.git.rgb@redhat.com>

fs/notify: constify path

Reviewed-by: Matthew Bobrowski <repnop@google.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fanotify: introduce FAN_MARK_IGNORE

This flag is a new way to configure ignore mask which allows adding and
removing the event flags FAN_ONDIR and FAN_EVENT_ON_CHILD in ignore mask.

The legacy FAN_MARK_IGNORED_MASK flag would always ignore events on
directories and would ignore events on children depending on whether
the FAN_EVENT_ON_CHILD flag was set in the (non ignored) mask.

FAN_MARK_IGNORE can be used to ignore events on children without setting
FAN_EVENT_ON_CHILD in the mark's mask and will not ignore events on
directories unconditionally, only when FAN_ONDIR is set in ignore mask.

The new behavior is non-downgradable. After calling fanotify_mark() with
FAN_MARK_IGNORE once, calling fanotify_mark() with FAN_MARK_IGNORED_MASK
on the same object will return EEXIST error.

Setting the event flags with FAN_MARK_IGNORE on a non-dir inode mark
has no meaning and will return ENOTDIR error.

The meaning of FAN_MARK_IGNORED_SURV_MODIFY is preserved with the new
FAN_MARK_IGNORE flag, but with a few semantic differences:

1. FAN_MARK_IGNORED_SURV_MODIFY is required for filesystem and mount
marks and on an inode mark on a directory. Omitting this flag
will return EINVAL or EISDIR error.

2. An ignore mask on a non-directory inode that survives modify could
never be downgraded to an ignore mask that does not survive modify.
With new FAN_MARK_IGNORE semantics we make that rule explicit -
trying to update a surviving ignore mask without the flag
FAN_MARK_IGNORED_SURV_MODIFY will return EEXIST error.

The conveniene macro FAN_MARK_IGNORE_SURV is added for
(FAN_MARK_IGNORE | FAN_MARK_IGNORED_SURV_MODIFY), because the
common case should use short constant names.

Link: https://lore.kernel.org/r/20220629144210.2983229-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: cleanups for fanotify_mark() input validations

Create helper fanotify_may_update_existing_mark() for checking for
conflicts between existing mark flags and fanotify_mark() flags.

Use variable mark_cmd to make the checks for mark command bits
cleaner.

Link: https://lore.kernel.org/r/20220629144210.2983229-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: prepare for setting event flags in ignore mask

Setting flags FAN_ONDIR FAN_EVENT_ON_CHILD in ignore mask has no effect.
The FAN_EVENT_ON_CHILD flag in mask implicitly applies to ignore mask and
ignore mask is always implicitly applied to events on directories.

Define a mark flag that replaces this legacy behavior with logic of
applying the ignore mask according to event flags in ignore mask.

Implement the new logic to prepare for supporting an ignore mask that
ignores events on children and ignore mask that does not ignore events
on directories.

To emphasize the change in terminology, also rename ignored_mask mark
member to ignore_mask and use accessors to get only the effective
ignored events or the ignored events and flags.

This change in terminology finally aligns with the "ignore mask"
language in man pages and in most of the comments.

Link: https://lore.kernel.org/r/20220629144210.2983229-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: refine the validation checks on non-dir inode mask

Commit ceaf69f8eadc ("fanotify: do not allow setting dirent events in
mask of non-dir") added restrictions about setting dirent events in the
mask of a non-dir inode mark, which does not make any sense.

For backward compatibility, these restictions were added only to new
(v5.17+) APIs.

It also does not make any sense to set the flags FAN_EVENT_ON_CHILD or
FAN_ONDIR in the mask of a non-dir inode. Add these flags to the
dir-only restriction of the new APIs as well.

Move the check of the dir-only flags for new APIs into the helper
fanotify_events_supported(), which is only called for FAN_MARK_ADD,
because there is no need to error on an attempt to remove the dir-only
flags from non-dir inode.

Fixes: ceaf69f8eadc ("fanotify: do not allow setting dirent events in mask of non-dir")
Link: https://lore.kernel.org/linux-fsdevel/20220627113224.kr2725conevh53u4@quack3.lan/
Link: https://lore.kernel.org/r/20220627174719.2838175-1-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: fix incorrect fmode_t casts

Fixes sparce warnings:
fs/notify/fanotify/fanotify_user.c:267:63: sparse:
warning: restricted fmode_t degrades to integer
fs/notify/fanotify/fanotify_user.c:1351:28: sparse:
warning: restricted fmode_t degrades to integer

FMODE_NONTIFY have bitwise fmode_t type and requires __force attribute
for any casts.

Signed-off-by: Vasily Averin <vvs@openvz.org>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/9adfd6ac-1b89-791e-796b-49ada3293985@openvz.org

fanotify: enable "evictable" inode marks

Now that the direct reclaim path is handled we can enable evictable
inode marks.

Link: https://lore.kernel.org/r/20220422120327.3459282-17-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: use fsnotify group lock helpers

Direct reclaim from fanotify mark allocation context may try to evict
inodes with evictable marks of the same group and hit this deadlock:

[<0>] fsnotify_destroy_mark+0x1f/0x3a
[<0>] fsnotify_destroy_marks+0x71/0xd9
[<0>] __destroy_inode+0x24/0x7e
[<0>] destroy_inode+0x2c/0x67
[<0>] dispose_list+0x49/0x68
[<0>] prune_icache_sb+0x5b/0x79
[<0>] super_cache_scan+0x11c/0x16f
[<0>] shrink_slab.constprop.0+0x23e/0x40f
[<0>] shrink_node+0x218/0x3e7
[<0>] do_try_to_free_pages+0x12a/0x2d2
[<0>] try_to_free_pages+0x166/0x242
[<0>] __alloc_pages_slowpath.constprop.0+0x30c/0x903
[<0>] __alloc_pages+0xeb/0x1c7
[<0>] cache_grow_begin+0x6f/0x31e
[<0>] fallback_alloc+0xe0/0x12d
[<0>] ____cache_alloc_node+0x15a/0x17e
[<0>] kmem_cache_alloc_trace+0xa1/0x143
[<0>] fanotify_add_mark+0xd5/0x2b2
[<0>] do_fanotify_mark+0x566/0x5eb
[<0>] __x64_sys_fanotify_mark+0x21/0x24
[<0>] do_syscall_64+0x6d/0x80
[<0>] entry_SYSCALL_64_after_hwframe+0x44/0xae

Set the FSNOTIFY_GROUP_NOFS flag to prevent going into direct reclaim
from allocations under fanotify group lock and use the safe group lock
helpers.

Link: https://lore.kernel.org/r/20220422120327.3459282-16-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: implement "evictable" inode marks

When an inode mark is created with flag FAN_MARK_EVICTABLE, it will not
pin the marked inode to inode cache, so when inode is evicted from cache
due to memory pressure, the mark will be lost.

When an inode mark with flag FAN_MARK_EVICATBLE is updated without using
this flag, the marked inode is pinned to inode cache.

When an inode mark is updated with flag FAN_MARK_EVICTABLE but an
existing mark already has the inode pinned, the mark update fails with
error EEXIST.

Evictable inode marks can be used to setup inode marks with ignored mask
to suppress events from uninteresting files or directories in a lazy
manner, upon receiving the first event, without having to iterate all
the uninteresting files or directories before hand.

The evictbale inode mark feature allows performing this lazy marks setup
without exhausting the system memory with pinned inodes.

This change does not enable the feature yet.

Link: https://lore.kernel.org/linux-fsdevel/CAOQ4uxiRDpuS=2uA6+ZUM7yG9vVU-u212tkunBmSnP_u=mkv=Q@mail.gmail.com/
Link: https://lore.kernel.org/r/20220422120327.3459282-15-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: factor out helper fanotify_mark_update_flags()

Handle FAN_MARK_IGNORED_SURV_MODIFY flag change in a helper that
is called after updating the mark mask.

Replace the added and removed return values and help variables with
bool recalc return values and help variable, which makes the code a
bit easier to follow.

Rename flags argument to fan_flags to emphasize the difference from
mark->flags.

Link: https://lore.kernel.org/r/20220422120327.3459282-14-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: pass flags argument to fsnotify_alloc_group()

Add flags argument to fsnotify_alloc_group(), define and use the flag
FSNOTIFY_GROUP_USER in inotify and fanotify instead of the helper
fsnotify_alloc_user_group() to indicate user allocation.

Although the flag FSNOTIFY_GROUP_USER is currently not used after group
allocation, we store the flags argument in the group struct for future
use of other group flags.

Link: https://lore.kernel.org/r/20220422120327.3459282-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: do not allow setting dirent events in mask of non-dir

Dirent events (create/delete/move) are only reported on watched
directory inodes, but in fanotify as well as in legacy inotify, it was
always allowed to set them on non-dir inode, which does not result in
any meaningful outcome.

Until kernel v5.17, dirent events in fanotify also differed from events
"on child" (e.g. FAN_OPEN) in the information provided in the event.
For example, FAN_OPEN could be set in the mask of a non-dir or the mask
of its parent and event would report the fid of the child regardless of
the marked object.
By contrast, FAN_DELETE is not reported if the child is marked and the
child fid was not reported in the events.

Since kernel v5.17, with fanotify group flag FAN_REPORT_TARGET_FID, the
fid of the child is reported with dirent events, like events "on child",
which may create confusion for users expecting the same behavior as
events "on child" when setting events in the mask on a child.

The desired semantics of setting dirent events in the mask of a child
are not clear, so for now, deny this action for a group initialized
with flag FAN_REPORT_TARGET_FID and for the new event FAN_RENAME.
We may relax this restriction in the future if we decide on the
semantics and implement them.

Fixes: d61fd650e9d2 ("fanotify: introduce group flag FAN_REPORT_TARGET_FID")
Fixes: 8cc3b1ccd930 ("fanotify: wire up FAN_RENAME event")
Link: https://lore.kernel.org/linux-fsdevel/20220505133057.zm5t6vumc4xdcnsg@quack3.lan/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220507080028.219826-1-amir73il@gmail.com

fsnotify: optimize FS_MODIFY events with no ignored masks

fsnotify() treats FS_MODIFY events specially - it does not skip them
even if the FS_MODIFY event does not apear in the object's fsnotify
mask. This is because send_to_group() checks if FS_MODIFY needs to
clear ignored mask of marks.

The common case is that an object does not have any mark with ignored
mask and in particular, that it does not have a mark with ignored mask
and without the FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag.

Set FS_MODIFY in object's fsnotify mask during fsnotify_recalc_mask()
if object has a mark with an ignored mask and without the
FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag and remove the special
treatment of FS_MODIFY in fsnotify(), so that FS_MODIFY events could
be optimized in the common case.

Call fsnotify_recalc_mask() from fanotify after adding or removing an
ignored mask from a mark without FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY
or when adding the FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag to a mark
with ignored mask (the flag cannot be removed by fanotify uapi).

Performance results for doing 10000000 write(2)s to tmpfs:

vanilla patched
without notification mark 25.486+-1.054 24.965+-0.244
with notification mark 30.111+-0.139 26.891+-1.355

So we can see the overhead of notification subsystem has been
drastically reduced.

Link: https://lore.kernel.org/r/20220223151438.790268-3-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: fix merge with parent's ignored mask

fsnotify_parent() does not consider the parent's mark at all unless
the parent inode shows interest in events on children and in the
specific event.

So unless parent added an event to both its mark mask and ignored mask,
the event will not be ignored.

Fix this by declaring the interest of an object in an event when the
event is in either a mark mask or ignored mask.

Link: https://lore.kernel.org/r/20220223151438.790268-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Fix stale file descriptor in copy_event_to_user()

This code calls fd_install() which gives the userspace access to the fd.
Then if copy_info_records_to_user() fails it calls put_unused_fd(fd) but
that will not release it and leads to a stale entry in the file
descriptor table.

Generally you can't trust the fd after a call to fd_install(). The fix
is to delay the fd_install() until everything else has succeeded.

Fortunately it requires CAP_SYS_ADMIN to reach this code so the security
impact is less.

Fixes: f644bc449b37 ("fanotify: fix copy_event_to_user() fid error clean up")
Link: https://lore.kernel.org/r/20220128195656.GA26981@kili
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: remove variable set but not used

The code that uses the pointer info has been removed in 7326e382c21e
("fanotify: report old and/or new parent+name in FAN_RENAME event").
and fanotify_event_info() doesn't change 'event', so the declaration and
assignment of info can be removed.

Eliminate the following clang warning:
fs/notify/fanotify/fanotify_user.c:161:24: warning: variable ‘info’ set
but not used

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Jan Kara <jack@suse.cz>

inotify: simplify subdirectory registration with register_sysctl()

There is no need to user boiler plate code to specify a set of base
directories we're going to stuff sysctls under. Simplify this by using
register_sysctl() and specifying the directory path directly.

Move inotify_user sysctl to inotify_user.c while at it to remove clutter
from kernel/sysctl.c.

[mcgrof@kernel.org: remember to register fanotify_table]
Link: https://lkml.kernel.org/r/YZ5A6iWLb0h3N3RC@bombadil.infradead.org
[mcgrof@kernel.org: update commit log to reflect new path we decided to take]

Link: https://lkml.kernel.org/r/20211123202422.819032-7-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Airlie <airlied@linux.ie>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Qing Wang <wangqing@vivo.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: wire up FAN_RENAME event

FAN_RENAME is the successor of FAN_MOVED_FROM and FAN_MOVED_TO
and can be used to get the old and new parent+name information in
a single event.

FAN_MOVED_FROM and FAN_MOVED_TO are still supported for backward
compatibility, but it makes little sense to use them together with
FAN_RENAME in the same group.

FAN_RENAME uses special info type records to report the old and
new parent+name, so reporting only old and new parent id is less
useful and was not implemented.
Therefore, FAN_REANAME requires a group with flag FAN_REPORT_NAME.

Link: https://lore.kernel.org/r/20211129201537.1932819-12-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: report old and/or new parent+name in FAN_RENAME event

In the special case of FAN_RENAME event, we report old or new or both
old and new parent+name.

A single info record will be reported if either the old or new dir
is watched and two records will be reported if both old and new dir
(or their filesystem) are watched.

The old and new parent+name are reported using new info record types
FAN_EVENT_INFO_TYPE_{OLD,NEW}_DFID_NAME, so if a single info record
is reported, it is clear to the application, to which dir entry the
fid+name info is referring to.

Link: https://lore.kernel.org/r/20211129201537.1932819-11-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: support secondary dir fh and name in fanotify_info

Allow storing a secondary dir fh and name tupple in fanotify_info.
This will be used to store the new parent and name information in
FAN_RENAME event.

Link: https://lore.kernel.org/r/20211129201537.1932819-8-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: introduce group flag FAN_REPORT_TARGET_FID

FAN_REPORT_FID is ambiguous in that it reports the fid of the child for
some events and the fid of the parent for create/delete/move events.

The new FAN_REPORT_TARGET_FID flag is an implicit request to report
the fid of the target object of the operation (a.k.a the child inode)
also in create/delete/move events in addition to the fid of the parent
and the name of the child.

To reduce the test matrix for uninteresting use cases, the new
FAN_REPORT_TARGET_FID flag requires both FAN_REPORT_NAME and
FAN_REPORT_FID. The convenience macro FAN_REPORT_DFID_NAME_TARGET
combines FAN_REPORT_TARGET_FID with all the required flags.

Link: https://lore.kernel.org/r/20211129201537.1932819-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: clarify object type argument

In preparation for separating object type from iterator type, rename
some 'type' arguments in functions to 'obj_type' and remove the unused
interface to clear marks by object type mask.

Link: https://lore.kernel.org/r/20211129201537.1932819-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Allow users to request FAN_FS_ERROR events

Wire up the FAN_FS_ERROR event in the fanotify_mark syscall, allowing
user space to request the monitoring of FAN_FS_ERROR events.

These events are limited to filesystem marks, so check it is the
case in the syscall handler.

Link: https://lore.kernel.org/r/20211025192746.66445-29-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Emit generic error info for error event

The error info is a record sent to users on FAN_FS_ERROR events
documenting the type of error. It also carries an error count,
documenting how many errors were observed since the last reporting.

Link: https://lore.kernel.org/r/20211025192746.66445-28-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Report fid info for file related file system errors

Plumb the pieces to add a FID report to error records. Since all error
event memory must be pre-allocated, we pre-allocate the maximum file
handle size possible, such that it should always fit.

For errors that don't expose a file handle, report it with an invalid
FID. Internally we use zero-length FILEID_ROOT file handle for passing
the information (which we report as zero-length FILEID_INVALID file
handle to userspace) so we update the handle reporting code to deal with
this case correctly.

Link: https://lore.kernel.org/r/20211025192746.66445-27-krisman@collabora.com
Link: https://lore.kernel.org/r/20211025192746.66445-25-krisman@collabora.com
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
[Folded two patches into 2 to make series bisectable]
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Add helpers to decide whether to report FID/DFID

Now that there is an event that reports FID records even for a zeroed
file handle, wrap the logic that deides whether to issue the records
into helper functions. This shouldn't have any impact on the code, but
simplifies further patches.

Link: https://lore.kernel.org/r/20211025192746.66445-24-krisman@collabora.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Pre-allocate pool of error events

Pre-allocate slots for file system errors to have greater chances of
succeeding, since error events can happen in GFP_NOFS context. This
patch introduces a group-wide mempool of error events, shared by all
FAN_FS_ERROR marks in this group.

Link: https://lore.kernel.org/r/20211025192746.66445-20-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Require fid_mode for any non-fd event

Like inode events, FAN_FS_ERROR will require fid mode. Therefore,
convert the verification during fanotify_mark(2) to require fid for any
non-fd event. This means fid_mode will not only be required for inode
events, but for any event that doesn't provide a descriptor.

Link: https://lore.kernel.org/r/20211025192746.66445-17-krisman@collabora.com
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Split fsid check from other fid mode checks

FAN_FS_ERROR will require fsid, but not necessarily require the
filesystem to expose a file handle. Split those checks into different
functions, so they can be used separately when setting up an event.

While there, update a comment about tmpfs having 0 fsid, which is no
longer true.

Link: https://lore.kernel.org/r/20211025192746.66445-7-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Fold event size calculation to its own function

Every time this function is invoked, it is immediately added to
FAN_EVENT_METADATA_LEN, since there is no need to just calculate the
length of info records. This minor clean up folds the rest of the
calculation into the function, which now operates in terms of events,
returning the size of the entire event, including metadata.

Link: https://lore.kernel.org/r/20211025192746.66445-6-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: add pidfd support to the fanotify API

Introduce a new flag FAN_REPORT_PIDFD for fanotify_init(2) which
allows userspace applications to control whether a pidfd information
record containing a pidfd is to be returned alongside the generic
event metadata for each event.

If FAN_REPORT_PIDFD is enabled for a notification group, an additional
struct fanotify_event_info_pidfd object type will be supplied
alongside the generic struct fanotify_event_metadata for a single
event. This functionality is analogous to that of FAN_REPORT_FID in
terms of how the event structure is supplied to a userspace
application. Usage of FAN_REPORT_PIDFD with
FAN_REPORT_FID/FAN_REPORT_DFID_NAME is permitted, and in this case a
struct fanotify_event_info_pidfd object will likely follow any struct
fanotify_event_info_fid object.

Currently, the usage of the FAN_REPORT_TID flag is not permitted along
with FAN_REPORT_PIDFD as the pidfd API currently only supports the
creation of pidfds for thread-group leaders. Additionally, usage of
the FAN_REPORT_PIDFD flag is limited to privileged processes only
i.e. event listeners that are running with the CAP_SYS_ADMIN
capability. Attempting to supply the FAN_REPORT_TID initialization
flags with FAN_REPORT_PIDFD or creating a notification group without
CAP_SYS_ADMIN will result with -EINVAL being returned to the caller.

In the event of a pidfd creation error, there are two types of error
values that can be reported back to the listener. There is
FAN_NOPIDFD, which will be reported in cases where the process
responsible for generating the event has terminated prior to the event
listener being able to read the event. Then there is FAN_EPIDFD, which
will be reported when a more generic pidfd creation error has occurred
when fanotify calls pidfd_create().

Link: https://lore.kernel.org/r/5f9e09cff7ed62bfaa51c1369e0f7ea5f16a91aa.1628398044.git.repnop@google.com
Signed-off-by: Matthew Bobrowski <repnop@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: introduce a generic info record copying helper

The copy_info_records_to_user() helper allows for the separation of
info record copying routines/conditionals from copy_event_to_user(),
which reduces the overall clutter within this function. This becomes
especially true as we start introducing additional info records in the
future i.e. struct fanotify_event_info_pidfd. On success, this helper
returns the total amount of bytes that have been copied into the user
supplied buffer and on error, a negative value is returned to the
caller.

The newly defined macro FANOTIFY_INFO_MODES can be used to obtain info
record types that have been enabled for a specific notification
group. This macro becomes useful in the subsequent patch when the
FAN_REPORT_PIDFD initialization flag is introduced.

Link: https://lore.kernel.org/r/8872947dfe12ce8ae6e9a7f2d49ea29bc8006af0.1628398044.git.repnop@google.com
Signed-off-by: Matthew Bobrowski <repnop@google.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: minor cosmetic adjustments to fid labels

With the idea to support additional info record types in the future
i.e. fanotify_event_info_pidfd, it's a good idea to rename some of the
labels assigned to some of the existing fid related functions,
parameters, etc which more accurately represent the intent behind
their usage.

For example, copy_info_to_user() was defined with a generic function
label, which arguably reads as being supportive of different info
record types, however the parameter list for this function is
explicitly tailored towards the creation and copying of the
fanotify_event_info_fid records. This same point applies to the macro
defined as FANOTIFY_INFO_HDR_LEN.

With fanotify_event_info_len(), we change the parameter label so that
the function implies that it can be extended to calculate the length
for additional info record types.

Link: https://lore.kernel.org/r/7c3ec33f3c718dac40764305d4d494d858f59c51.1628398044.git.repnop@google.com
Signed-off-by: Matthew Bobrowski <repnop@google.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

ucounts: add missing data type changes

commit f9c82a4ea89c3 ("Increase size of ucounts to atomic_long_t")
changed the data type of ucounts/ucounts_max to long, but missed to
adjust a few other places. This is noticeable on big endian platforms
from user space because the /proc/sys/user/max_*_names files all
contain 0.

v4 - Made the min and max constants long so the sysctl values
are actually settable on little endian machines.
-- EWB

Fixes: f9c82a4ea89c ("Increase size of ucounts to atomic_long_t")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Acked-by: Alexey Gladkov <legion@kernel.org>
v1: https://lkml.kernel.org/r/20210721115800.910778-1-svens@linux.ibm.com
v2: https://lkml.kernel.org/r/20210721125233.1041429-1-svens@linux.ibm.com
v3: https://lkml.kernel.org/r/20210730062854.3601635-1-svens@linux.ibm.com
Link: https://lkml.kernel.org/r/8735rijqlv.fsf_-_@disp2133
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fanotify: fix copy_event_to_user() fid error clean up

Ensure that clean up is performed on the allocated file descriptor and
struct file object in the event that an error is encountered while copying
fid info objects. Currently, we return directly to the caller when an error
is experienced in the fid info copying helper, which isn't ideal given that
the listener process could be left with a dangling file descriptor in their
fdtable.

Fixes: 5e469c830fdb ("fanotify: copy event fid info to user")
Fixes: 44d705b0370b ("fanotify: report name info for FAN_DIR_MODIFY event")
Link: https://lore.kernel.org/linux-fsdevel/YMKv1U7tNPK955ho@google.com/T/#m15361cd6399dad4396aad650de25dbf6b312288e
Link: https://lore.kernel.org/r/1ef8ae9100101eb1a91763c516c2e9a3a3b112bd.1623376346.git.repnop@google.com
Signed-off-by: Matthew Bobrowski <repnop@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: fix permission model of unprivileged group

Reporting event->pid should depend on the privileges of the user that
initialized the group, not the privileges of the user reading the
events.

Use an internal group flag FANOTIFY_UNPRIV to record the fact that the
group was initialized by an unprivileged user.

To be on the safe side, the premissions to setup filesystem and mount
marks now require that both the user that initialized the group and
the user setting up the mark have CAP_SYS_ADMIN.

Link: https://lore.kernel.org/linux-fsdevel/CAOQ4uxiA77_P5vtv7e83g0+9d7B5W9ZTE4GfQEYbWmfT1rA=VA@mail.gmail.com/
Fixes: 7cea2a3c505e ("fanotify: support limited functionality for unprivileged users")
Cc: <Stable@vger.kernel.org> # v5.12+
Link: https://lore.kernel.org/r/20210524135321.2190062-1-amir73il@gmail.com
Reviewed-by: Matthew Bobrowski <repnop@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify_user: use upper_32_bits() to verify mask

I don't see an obvious reason why the upper 32 bit check needs to be
open-coded this way. Switch to upper_32_bits() which is more idiomatic and
should conceptually be the same check.

Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210325083742.2334933-1-brauner@kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: support limited functionality for unprivileged users

Add limited support for unprivileged fanotify groups.
An unprivileged users is not allowed to get an open file descriptor in
the event nor the process pid of another process. An unprivileged user
cannot request permission events, cannot set mount/filesystem marks and
cannot request unlimited queue/marks.

This enables the limited functionality similar to inotify when watching a
set of files and directories for OPEN/ACCESS/MODIFY/CLOSE events, without
requiring SYS_CAP_ADMIN privileges.

The FAN_REPORT_DFID_NAME init flag, provide a method for an unprivileged
listener watching a set of directories (with FAN_EVENT_ON_CHILD) to monitor
all changes inside those directories.

This typically requires that the listener keeps a map of watched directory
fid to dirfd (O_PATH), where fid is obtained with name_to_handle_at()
before starting to watch for changes.

When getting an event, the reported fid of the parent should be resolved
to dirfd and fstatsat(2) with dirfd and name should be used to query the
state of the filesystem entry.

Link: https://lore.kernel.org/r/20210304112921.3996419-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: configurable limits via sysfs

fanotify has some hardcoded limits. The only APIs to escape those limits
are FAN_UNLIMITED_QUEUE and FAN_UNLIMITED_MARKS.

Allow finer grained tuning of the system limits via sysfs tunables under
/proc/sys/fs/fanotify, similar to tunables under /proc/sys/fs/inotify,
with some minor differences.

- max_queued_events - global system tunable for group queue size limit.
Like the inotify tunable with the same name, it defaults to 16384 and
applies on initialization of a new group.

- max_user_marks - user ns tunable for marks limit per user.
Like the inotify tunable named max_user_watches, on a machine with
sufficient RAM and it defaults to 1048576 in init userns and can be
further limited per containing user ns.

- max_user_groups - user ns tunable for number of groups per user.
Like the inotify tunable named max_user_instances, it defaults to 128
in init userns and can be further limited per containing user ns.

The slightly different tunable names used for fanotify are derived from
the "group" and "mark" terminology used in the fanotify man pages and
throughout the code.

Considering the fact that the default value for max_user_instances was
increased in kernel v5.10 from 8192 to 1048576, leaving the legacy
fanotify limit of 8192 marks per group in addition to the max_user_marks
limit makes little sense, so the per group marks limit has been removed.

Note that when a group is initialized with FAN_UNLIMITED_MARKS, its own
marks are not accounted in the per user marks account, so in effect the
limit of max_user_marks is only for the collection of groups that are
not initialized with FAN_UNLIMITED_MARKS.

Link: https://lore.kernel.org/r/20210304112921.3996419-2-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: use hash table for faster events merge

In order to improve event merge performance, hash events in a 128 size
hash table by the event merge key.

The fanotify_event size grows by two pointers, but we just reduced its
size by removing the objectid member, so overall its size is increased
by one pointer.

Permission events and overflow event are not merged so they are also
not hashed.

Link: https://lore.kernel.org/r/20210304104826.3993892-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: allow fsnotify_{peek,remove}_first_event with empty queue

Current code has an assumtion that fsnotify_notify_queue_is_empty() is
called to verify that queue is not empty before trying to peek or remove
an event from queue.

Remove this assumption by moving the fsnotify_notify_queue_is_empty()
into the functions, allow them to return NULL value and check return
value by all callers.

This is a prep patch for multi event queues.

Link: https://lore.kernel.org/r/20210304104826.3993892-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

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>

inotify, memcg: account inotify instances to kmemcg

Currently the fs sysctl inotify/max_user_instances is used to limit the
number of inotify instances on the system. For systems running multiple
workloads, the per-user namespace sysctl max_inotify_instances can be
used to further partition inotify instances. However there is no easy
way to set a sensible system level max limit on inotify instances and
further partition it between the workloads. It is much easier to charge
the underlying resource (i.e. memory) behind the inotify instances to
the memcg of the workload and let their memory limits limit the number
of inotify instances they can create.

With inotify instances charged to memcg, the admin can simply set
max_user_instances to INT_MAX and let the memcg limits of the jobs limit
their inotify instances.

Link: https://lore.kernel.org/r/20201220044608.1258123-1-shakeelb@google.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Fix sys_fanotify_mark() on native x86-32

Commit

121b32a58a3a ("x86/entry/32: Use IA32-specific wrappers for syscalls taking 64-bit arguments")

converted native x86-32 which take 64-bit arguments to use the
compat handlers to allow conversion to passing args via pt_regs.
sys_fanotify_mark() was however missed, as it has a general compat
handler. Add a config option that will use the syscall wrapper that
takes the split args for native 32-bit.

[ bp: Fix typo in Kconfig help text. ]

Fixes: 121b32a58a3a ("x86/entry/32: Use IA32-specific wrappers for syscalls taking 64-bit arguments")
Reported-by: Paweł Jasiak <pawel@jasiak.xyz>
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20201130223059.101286-1-brgerst@gmail.com

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>

fanotify: report parent fid + child fid

Add support for FAN_REPORT_FID | FAN_REPORT_DIR_FID.
Internally, it is implemented as a private case of reporting both
parent and child fids and name, the parent and child fids are recorded
in a variable length fanotify_name_event, but there is no name.

It should be noted that directory modification events are recorded
in fixed size fanotify_fid_event when not reporting name, just like
with group flags FAN_REPORT_FID.

Link: https://lore.kernel.org/r/20200716084230.30611-23-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: report parent fid + name + child fid

For a group with fanotify_init() flag FAN_REPORT_DFID_NAME, the parent
fid and name are reported for events on non-directory objects with an
info record of type FAN_EVENT_INFO_TYPE_DFID_NAME.

If the group also has the init flag FAN_REPORT_FID, the child fid
is also reported with another info record that follows the first info
record. The second info record is the same info record that would have
been reported to a group with only FAN_REPORT_FID flag.

When the child fid needs to be recorded, the variable size struct
fanotify_name_event is preallocated with enough space to store the
child fh between the dir fh and the name.

Link: https://lore.kernel.org/r/20200716084230.30611-22-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: add support for FAN_REPORT_NAME

Introduce a new fanotify_init() flag FAN_REPORT_NAME. It requires the
flag FAN_REPORT_DIR_FID and there is a constant for setting both flags
named FAN_REPORT_DFID_NAME.

For a group with flag FAN_REPORT_NAME, the parent fid and name are
reported for directory entry modification events (create/detete/move)
and for events on non-directory objects.

Events on directories themselves are reported with their own fid and
"." as the name.

The parent fid and name are reported with an info record of type
FAN_EVENT_INFO_TYPE_DFID_NAME, similar to the way that parent fid is
reported with into type FAN_EVENT_INFO_TYPE_DFID, but with an appended
null terminated name string.

Link: https://lore.kernel.org/r/20200716084230.30611-21-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: report events with parent dir fid to sb/mount/non-dir marks

In a group with flag FAN_REPORT_DIR_FID, when adding an inode mark with
FAN_EVENT_ON_CHILD, events on non-directory children are reported with
the fid of the parent.

When adding a filesystem or mount mark or mark on a non-dir inode, we
want to report events that are "possible on child" (e.g. open/close)
also with fid of the parent, as if the victim inode's parent is
interested in events "on child".

Some events, currently only FAN_MOVE_SELF, should be reported to a
sb/mount/non-dir mark with parent fid even though they are not
reported to a watching parent.

To get the desired behavior we set the flag FAN_EVENT_ON_CHILD on
all the sb/mount/non-dir mark masks in a group with FAN_REPORT_DIR_FID.

Link: https://lore.kernel.org/r/20200716084230.30611-20-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: add basic support for FAN_REPORT_DIR_FID

For now, the flag is mutually exclusive with FAN_REPORT_FID.
Events include a single info record of type FAN_EVENT_INFO_TYPE_DFID
with a directory file handle.

For now, events are only reported for:
- Directory modification events
- Events on children of a watching directory
- Events on directory objects

Soon, we will add support for reporting the parent directory fid
for events on non-directories with filesystem/mount mark and
support for reporting both parent directory fid and child fid.

Link: https://lore.kernel.org/r/20200716084230.30611-19-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: use struct fanotify_info to parcel the variable size buffer

An fanotify event name is always recorded relative to a dir fh.
Encapsulate the name_len member of fanotify_name_event in a new struct
fanotify_info, which describes the parceling of the variable size
buffer of an fanotify_name_event.

The dir_fh member of fanotify_name_event is renamed to _dir_fh and is not
accessed directly, but via the fanotify_info_dir_fh() accessor.
Although the dir_fh len information is already available in struct
fanotify_fh, we store it also in dif_fh_totlen member of fanotify_info,
including the size of fanotify_fh header, so we know the offset of the
name in the buffer without looking inside the dir_fh.

We also add a file_fh_totlen member to allow packing another file handle
in the variable size buffer after the dir_fh and before the name.
We are going to use that space to store the child fid.

Link: https://lore.kernel.org/r/20200716084230.30611-10-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: use FAN_EVENT_ON_CHILD as implicit flag on sb/mount/non-dir marks

Up to now, fanotify allowed to set the FAN_EVENT_ON_CHILD flag on
sb/mount marks and non-directory inode mask, but the flag was ignored.

Mask out the flag if it is provided by user on sb/mount/non-dir marks
and define it as an implicit flag that cannot be removed by user.

This flag is going to be used internally to request for events with
parent and name info.

Link: https://lore.kernel.org/r/20200716084230.30611-8-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: prepare for implicit event flags in mark mask

So far, all flags that can be set in an fanotify mark mask can be set
explicitly by a call to fanotify_mark(2).

Prepare for defining implicit event flags that cannot be set by user with
fanotify_mark(2), similar to how inotify/dnotify implicitly set the
FS_EVENT_ON_CHILD flag.

Implicit event flags cannot be removed by user and mark gets destroyed
when only implicit event flags remain in the mask.

Link: https://lore.kernel.org/r/20200716084230.30611-7-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: mask out special event flags from ignored mask

The special event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) never had
any meaning in ignored mask. Mask them out explicitly.

Link: https://lore.kernel.org/r/20200716084230.30611-6-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: generalize test for FAN_REPORT_FID

As preparation for new flags that report fids, define a bit set
of flags for a group reporting fids, currently containing the
only bit FAN_REPORT_FID.

Link: https://lore.kernel.org/r/20200716084230.30611-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: create overflow event type

The special overflow event is allocated as struct fanotify_path_event,
but with a null path.

Use a special event type to identify the overflow event, so the helper
fanotify_has_event_path() will always indicate a non null path.

Allocating the overflow event doesn't need any of the fancy stuff in
fanotify_alloc_event(), so create a simplified helper for allocating the
overflow event.

There is also no need to store and report the pid with an overflow event.

Link: https://lore.kernel.org/r/20200708111156.24659-7-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Avoid softlockups when reading many events

When user provides large buffer for events and there are lots of events
available, we can try to copy them all to userspace without scheduling
which can softlockup the kernel (furthermore exacerbated by the
contention on notification_lock). Add a scheduling point after copying
each event.

Note that usually the real underlying problem is the cost of fanotify
event merging and the resulting contention on notification_lock but this
is a cheap way to somewhat reduce the problem until we can properly
address that.

Reported-by: Francesco Ruggeri <fruggeri@arista.com>
Link: https://lore.kernel.org/lkml/20200714025417.A25EB95C0339@us180.sjc.aristanetworks.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: don't write with size under sizeof(response)

fanotify_write() only aligned copy_from_user size to sizeof(response)
for higher values. This patch avoids all values below as suggested
by Amir Goldstein and set to response size unconditionally.

Link: https://lore.kernel.org/r/20200512181921.405973-1-fabf@skynet.be
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: remove reference to fill_event_metadata()

fill_event_metadata() was removed in commit bb2f7b4542c7
("fanotify: open code fill_event_metadata()")

Link: https://lore.kernel.org/r/20200512181836.405879-1-fabf@skynet.be
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: report name info for FAN_DIR_MODIFY event

Report event FAN_DIR_MODIFY with name in a variable length record similar
to how fid's are reported. With name info reporting implemented, setting
FAN_DIR_MODIFY in mark mask is now allowed.

When events are reported with name, the reported fid identifies the
directory and the name follows the fid. The info record type for this
event info is FAN_EVENT_INFO_TYPE_DFID_NAME.

For now, all reported events have at most one info record which is
either FAN_EVENT_INFO_TYPE_FID or FAN_EVENT_INFO_TYPE_DFID_NAME (for
FAN_DIR_MODIFY). Later on, events "on child" will report both records.

There are several ways that an application can use this information:

1. When watching a single directory, the name is always relative to
the watched directory, so application need to fstatat(2) the name
relative to the watched directory.

2. When watching a set of directories, the application could keep a map
of dirfd for all watched directories and hash the map by fid obtained
with name_to_handle_at(2). When getting a name event, the fid in the
event info could be used to lookup the base dirfd in the map and then
call fstatat(2) with that dirfd.

3. When watching a filesystem (FAN_MARK_FILESYSTEM) or a large set of
directories, the application could use open_by_handle_at(2) with the fid
in event info to obtain dirfd for the directory where event happened and
call fstatat(2) with this dirfd.

The last option scales better for a large number of watched directories.
The first two options may be available in the future also for non
privileged fanotify watchers, because open_by_handle_at(2) requires
the CAP_DAC_READ_SEARCH capability.

Link: https://lore.kernel.org/r/20200319151022.31456-15-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: record name info for FAN_DIR_MODIFY event

For FAN_DIR_MODIFY event, allocate a variable size event struct to store
the dir entry name along side the directory file handle.

At this point, name info reporting is not yet implemented, so trying to
set FAN_DIR_MODIFY in mark mask will return -EINVAL.

Link: https://lore.kernel.org/r/20200319151022.31456-14-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Drop fanotify_event_has_fid()

When some events have directory id and some object id,
fanotify_event_has_fid() becomes mostly useless and confusing because we
usually need to know which type of file handle the event has. So just
drop the function and use fanotify_event_object_fh() instead.

Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: prepare to report both parent and child fid's

For some events, we are going to report both child and parent fid's,
so pass fsid and file handle as arguments to copy_fid_to_user(),
which is going to be called with parent and child file handles.

Link: https://lore.kernel.org/r/20200319151022.31456-13-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: divorce fanotify_path_event and fanotify_fid_event

Breakup the union and make them both inherit from abstract fanotify_event.

fanotify_path_event, fanotify_fid_event and fanotify_perm_event inherit
from fanotify_event.

type field in abstract fanotify_event determines the concrete event type.

fanotify_path_event, fanotify_fid_event and fanotify_perm_event are
allocated from separate memcache pools.

Rename fanotify_perm_event casting macro to FANOTIFY_PERM(), so that
FANOTIFY_PE() and FANOTIFY_FE() can be used as casting macros to
fanotify_path_event and fanotify_fid_event.

[JK: Cleanup FANOTIFY_PE() and FANOTIFY_FE() to be proper inline
functions and remove requirement that fanotify_event is the first in
event structures]

Link: https://lore.kernel.org/r/20200319151022.31456-11-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Store fanotify handles differently

Currently, struct fanotify_fid groups fsid and file handle and is
unioned together with struct path to save space. Also there is fh_type
and fh_len directly in struct fanotify_event to avoid padding overhead.
In the follwing patches, we will be adding more event types and this
packing makes code difficult to follow. So unpack everything and create
struct fanotify_fh which groups members logically related to file handle
to make code easier to follow. In the following patch we will pack
things again differently to make events smaller.

Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Simplify create_fd()

create_fd() is never used with invalid path. Also the only thing it
needs to know from fanotify_event is the path. Simplify the function to
take path directly and assume it is correct.

Signed-off-by: Jan Kara <jack@suse.cz>

compat_ioctl: move more drivers to compat_ptr_ioctl

The .ioctl and .compat_ioctl file operations have the same prototype so
they can both point to the same function, which works great almost all
the time when all the commands are compatible.

One exception is the s390 architecture, where a compat pointer is only
31 bit wide, and converting it into a 64-bit pointer requires calling
compat_ptr(). Most drivers here will never run in s390, but since we now
have a generic helper for it, it's easy enough to use it consistently.

I double-checked all these drivers to ensure that all ioctl arguments
are used as pointers or are ignored, but are not interpreted as integer
values.

Acked-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Darren Hart (VMware) <dvhart@infradead.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

fanotify, inotify, dnotify, security: add security hook for fs notifications

As of now, setting watches on filesystem objects has, at most, applied a
check for read access to the inode, and in the case of fanotify, requires
CAP_SYS_ADMIN. No specific security hook or permission check has been
provided to control the setting of watches. Using any of inotify, dnotify,
or fanotify, it is possible to observe, not only write-like operations, but
even read access to a file. Modeling the watch as being merely a read from
the file is insufficient for the needs of SELinux. This is due to the fact
that read access should not necessarily imply access to information about
when another process reads from a file. Furthermore, fanotify watches grant
more power to an application in the form of permission events. While
notification events are solely, unidirectional (i.e. they only pass
information to the receiving application), permission events are blocking.
Permission events make a request to the receiving application which will
then reply with a decision as to whether or not that action may be
completed. This causes the issue of the watching application having the
ability to exercise control over the triggering process. Without drawing a
distinction within the permission check, the ability to read would imply
the greater ability to control an application. Additionally, mount and
superblock watches apply to all files within the same mount or superblock.
Read access to one file should not necessarily imply the ability to watch
all files accessed within a given mount or superblock.

In order to solve these issues, a new LSM hook is implemented and has been
placed within the system calls for marking filesystem objects with inotify,
fanotify, and dnotify watches. These calls to the hook are placed at the
point at which the target path has been resolved and are provided with the
path struct, the mask of requested notification events, and the type of
object on which the mark is being set (inode, superblock, or mount). The
mask and obj_type have already been translated into common FS_* values
shared by the entirety of the fs notification infrastructure. The path
struct is passed rather than just the inode so that the mount is available,
particularly for mount watches. This also allows for use of the hook by
pathname-based security modules. However, since the hook is intended for
use even by inode based security modules, it is not placed under the
CONFIG_SECURITY_PATH conditional. Otherwise, the inode-based security
modules would need to enable all of the path hooks, even though they do not
use any of them.

This only provides a hook at the point of setting a watch, and presumes
that permission to set a particular watch implies the ability to receive
all notification about that object which match the mask. This is all that
is required for SELinux. If other security modules require additional hooks
or infrastructure to control delivery of notification, these can be added
by them. It does not make sense for us to propose hooks for which we have
no implementation. The understanding that all notifications received by the
requesting application are all strictly of a type for which the application
has been granted permission shows that this implementation is sufficient in
its coverage.

Security modules wishing to provide complete control over fanotify must
also implement a security_file_open hook that validates that the access
requested by the watching application is authorized. Fanotify has the issue
that it returns a file descriptor with the file mode specified during
fanotify_init() to the watching process on event. This is already covered
by the LSM security_file_open hook if the security module implements
checking of the requested file mode there. Otherwise, a watching process
can obtain escalated access to a file for which it has not been authorized.

The selinux_path_notify hook implementation works by adding five new file
permissions: watch, watch_mount, watch_sb, watch_reads, and watch_with_perm
(descriptions about which will follow), and one new filesystem permission:
watch (which is applied to superblock checks). The hook then decides which
subset of these permissions must be held by the requesting application
based on the contents of the provided mask and the obj_type. The
selinux_file_open hook already checks the requested file mode and therefore
ensures that a watching process cannot escalate its access through
fanotify.

The watch, watch_mount, and watch_sb permissions are the baseline
permissions for setting a watch on an object and each are a requirement for
any watch to be set on a file, mount, or superblock respectively. It should
be noted that having either of the other two permissions (watch_reads and
watch_with_perm) does not imply the watch, watch_mount, or watch_sb
permission. Superblock watches further require the filesystem watch
permission to the superblock. As there is no labeled object in view for
mounts, there is no specific check for mount watches beyond watch_mount to
the inode. Such a check could be added in the future, if a suitable labeled
object existed representing the mount.

The watch_reads permission is required to receive notifications from
read-exclusive events on filesystem objects. These events include accessing
a file for the purpose of reading and closing a file which has been opened
read-only. This distinction has been drawn in order to provide a direct
indication in the policy for this otherwise not obvious capability. Read
access to a file should not necessarily imply the ability to observe read
events on a file.

Finally, watch_with_perm only applies to fanotify masks since it is the
only way to set a mask which allows for the blocking, permission event.
This permission is needed for any watch which is of this type. Though
fanotify requires CAP_SYS_ADMIN, this is insufficient as it gives implicit
trust to root, which we do not do, and does not support least privilege.

Signed-off-by: Aaron Goidel <acgoide@tycho.nsa.gov>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>

fanotify: Disallow permission events for proc filesystem

Proc filesystem has special locking rules for various files. Thus
fanotify which opens files on event delivery can easily deadlock
against another process that waits for fanotify permission event to be
handled. Since permission events on /proc have doubtful value anyway,
just disallow them.

Link: https://lore.kernel.org/linux-fsdevel/20190320131642.GE9485@quack2.suse.cz/
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Allow copying of file handle to userspace

When file handle is embedded inside fanotify_event and usercopy checks
are enabled, we get a warning like:

Bad or missing usercopy whitelist? Kernel memory exposure attempt detected
from SLAB object 'fanotify_event' (offset 40, size 8)!
WARNING: CPU: 1 PID: 7649 at mm/usercopy.c:78 usercopy_warn+0xeb/0x110
mm/usercopy.c:78

Annotate handling in fanotify_event properly to mark copying it to
userspace is fine.

Reported-by: syzbot+2c49971e251e36216d1f@syzkaller.appspotmail.com
Fixes: a8b13aa20afb ("fanotify: enable FAN_REPORT_FID init flag")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Use interruptible wait when waiting for permission events

When waiting for response to fanotify permission events, we currently
use uninterruptible waits. That makes code simple however it can cause
lots of processes to end up in uninterruptible sleep with hard reboot
being the only alternative in case fanotify listener process stops
responding (e.g. due to a bug in its implementation). Uninterruptible
sleep also makes system hibernation fail if the listener gets frozen
before the process generating fanotify permission event.

Fix these problems by using interruptible sleep for waiting for response
to fanotify event. This is slightly tricky though - we have to
detect when the event got already reported to userspace as in that
case we must not free the event. Instead we push the responsibility for
freeing the event to the process that will write response to the
event.

Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Track permission event state

Track whether permission event got already reported to userspace and
whether userspace already answered to the permission event. Protect
stores to this field together with updates to ->response field by
group->notification_lock. This will allow aborting wait for reply to
permission event from userspace.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Simplify cleaning of access_list

Simplify iteration cleaning access_list in fanotify_release(). That will
make following changes more obvious.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Move locking inside get_one_event()

get_one_event() has a single caller and that just locks
notification_lock around the call. Move locking inside get_one_event()
as that will make using ->response field for permission event state
easier.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Fold dequeue_event() into process_access_response()

Fold dequeue_event() into process_access_response(). This will make
changes to use of ->response field easier.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: add support for create/attrib/move/delete events

Add support for events with data type FSNOTIFY_EVENT_INODE
(e.g. create/attrib/move/delete) for inode and filesystem mark types.

The "inode" events do not carry enough information (i.e. path) to
report event->fd, so we do not allow setting a mask for those events
unless group supports reporting fid.

The "inode" events are not supported on a mount mark, because they do
not carry enough information (i.e. path) to be filtered by mount point.

The "dirent" events (create/move/delete) report the fid of the parent
directory where events took place without specifying the filename of the
child. In the future, fanotify may get support for reporting filename
information for those events.

Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: support events with data type FSNOTIFY_EVENT_INODE

When event data type is FSNOTIFY_EVENT_INODE, we don't have a refernece
to the mount, so we will not be able to open a file descriptor when user
reads the event. However, if the listener has enabled reporting file
identifier with the FAN_REPORT_FID init flag, we allow reporting those
events and we use an identifier inode to encode fid.

The inode to use as identifier when reporting fid depends on the event.
For dirent modification events, we report the modified directory inode
and we report the "victim" inode otherwise.
For example:
FS_ATTRIB reports the child inode even if reported on a watched parent.
FS_CREATE reports the modified dir inode and not the created inode.

[JK: Fixup condition in fanotify_group_event_mask()]

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: use vfs_get_fsid() helper instead of vfs_statfs()

This is a cleanup that doesn't change any logic.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: cache fsid in fsnotify_mark_connector

For FAN_REPORT_FID, we need to encode fid with fsid of the filesystem on
every event. To avoid having to call vfs_statfs() on every event to get
fsid, we store the fsid in fsnotify_mark_connector on the first time we
add a mark and on handle event we use the cached fsid.

Subsequent calls to add mark on the same object are expected to pass the
same fsid, so the call will fail on cached fsid mismatch.

If an event is reported on several mark types (inode, mount, filesystem),
all connectors should already have the same fsid, so we use the cached
fsid from the first connector.

[JK: Simplify code flow around fanotify_get_fid()
make fsid argument of fsnotify_add_mark_locked() unconditional]

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: enable FAN_REPORT_FID init flag

When setting up an fanotify listener, user may request to get fid
information in event instead of an open file descriptor.

The fid obtained with event on a watched object contains the file
handle returned by name_to_handle_at(2) and fsid returned by statfs(2).

Restrict FAN_REPORT_FID to class FAN_CLASS_NOTIF, because we have have
no good reason to support reporting fid on permission events.

When setting a mark, we need to make sure that the filesystem
supports encoding file handles with name_to_handle_at(2) and that
statfs(2) encodes a non-zero fsid.

Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: copy event fid info to user

If group requested FAN_REPORT_FID and event has file identifier,
copy that information to user reading the event after event metadata.

fid information is formatted as struct fanotify_event_info_fid
that includes a generic header struct fanotify_event_info_header,
so that other info types could be defined in the future using the
same header.

metadata->event_len includes the length of the fid information.

The fid information includes the filesystem's fsid (see statfs(2))
followed by an NFS file handle of the file that could be passed as
an argument to open_by_handle_at(2).

Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: encode file identifier for FAN_REPORT_FID

When user requests the flag FAN_REPORT_FID in fanotify_init(),
a unique file identifier of the event target object will be reported
with the event.

The file identifier includes the filesystem's fsid (i.e. from statfs(2))
and an NFS file handle of the file (i.e. from name_to_handle_at(2)).

The file identifier makes holding the path reference and passing a file
descriptor to user redundant, so those are disabled in a group with
FAN_REPORT_FID.

Encode fid and store it in event for a group with FAN_REPORT_FID.
Up to 12 bytes of file handle on 32bit arch (16 bytes on 64bit arch)
are stored inline in fanotify_event struct. Larger file handles are
stored in an external allocated buffer.

On failure to encode fid, we print a warning and queue the event
without the fid information.

[JK: Fold part of later patched into this one to use
exportfs_encode_inode_fh() right away]

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: open code fill_event_metadata()

The helper is quite trivial and open coding it will make it easier
to implement copying event fid info to user.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: rename struct fanotify_{,perm_}event_info

struct fanotify_event_info "inherits" from struct fsnotify_event and
therefore a more appropriate (and short) name for it is fanotify_event.
Same for struct fanotify_perm_event_info, which now "inherits" from
struct fanotify_event.

We plan to reuse the name struct fanotify_event_info for user visible
event info record format.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: move mask out of struct fsnotify_event

Common fsnotify_event helpers have no need for the mask field.
It is only used by backend code, so move the field out of the
abstract fsnotify_event struct and into the concrete backend
event structs.

This change packs struct inotify_event_info better on 64bit
machine and will allow us to cram some more fields into
struct fanotify_event_info.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Use inode_is_open_for_write

Use the aptly named function rather than opencoding i_writecount check.
No functional changes.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Make sure to check event_len when copying

As a precaution, make sure we check event_len when copying to userspace.
Based on old feedback: https://lkml.kernel.org/r/542D9FE5.3010009@gmx.de

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: support reporting thread id instead of process id

In order to identify which thread triggered the event in a
multi-threaded program, add the FAN_REPORT_TID flag in fanotify_init to
opt-in for reporting the event creator's thread id information.

Signed-off-by: nixiaoming <nixiaoming@huawei.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: add BUILD_BUG_ON() to count the bits of fanotify constants

Also define the FANOTIFY_EVENT_FLAGS consisting of the extra flags
FAN_ONDIR and FAN_ON_CHILD.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: deprecate uapi FAN_ALL_* constants

We do not want to add new bits to the FAN_ALL_* uapi constants
because they have been exposed to userspace. If there are programs
out there using these constants, those programs could break if
re-compiled with modified FAN_ALL_* constants and run on an old kernel.

We deprecate the uapi constants FAN_ALL_* and define new FANOTIFY_*
constants for internal use to replace them. New feature bits will be
added only to the new constants.

Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: simplify handling of FAN_ONDIR

fanotify mark add/remove code jumps through hoops to avoid setting the
FS_ISDIR in the commulative object mask.

That was just papering over a bug in fsnotify() handling of the FS_ISDIR
extra flag. This bug is now fixed, so all the hoops can be removed along
with the unneeded internal flag FAN_MARK_ONDIR.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: store fanotify_init() flags in group's fanotify_data

This averts the need to re-generate flags in fanotify_show_fdinfo()
and sets the scene for addition of more upcoming flags without growing
new members to the fanotify_data struct.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: add API to attach/detach super block mark

Add another mark type flag FAN_MARK_FILESYSTEM for add/remove/flush
of super block mark type.

A super block watch gets all events on the filesystem, regardless of
the mount from which the mark was added, unless an ignore mask exists
on either the inode or the mount where the event was generated.

Only one of FAN_MARK_MOUNT and FAN_MARK_FILESYSTEM mark type flags
may be provided to fanotify_mark() or no mark type flag for inode mark.

Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs: fsnotify: account fsnotify metadata to kmemcg

Patch series "Directed kmem charging", v8.

The Linux kernel's memory cgroup allows limiting the memory usage of the
jobs running on the system to provide isolation between the jobs. All
the kernel memory allocated in the context of the job and marked with
__GFP_ACCOUNT will also be included in the memory usage and be limited
by the job's limit.

The kernel memory can only be charged to the memcg of the process in
whose context kernel memory was allocated. However there are cases
where the allocated kernel memory should be charged to the memcg
different from the current processes's memcg. This patch series
contains two such concrete use-cases i.e. fsnotify and buffer_head.

The fsnotify event objects can consume a lot of system memory for large
or unlimited queues if there is either no or slow listener. The events
are allocated in the context of the event producer. However they should
be charged to the event consumer. Similarly the buffer_head objects can
be allocated in a memcg different from the memcg of the page for which
buffer_head objects are being allocated.

To solve this issue, this patch series introduces mechanism to charge
kernel memory to a given memcg. In case of fsnotify events, the memcg
of the consumer can be used for charging and for buffer_head, the memcg
of the page can be charged. For directed charging, the caller can use
the scope API memalloc_[un]use_memcg() to specify the memcg to charge
for all the __GFP_ACCOUNT allocations within the scope.

This patch (of 2):

A lot of memory can be consumed by the events generated for the huge or
unlimited queues if there is either no or slow listener. This can cause
system level memory pressure or OOMs. So, it's better to account the
fsnotify kmem caches to the memcg of the listener.

However the listener can be in a different memcg than the memcg of the
producer and these allocations happen in the context of the event
producer. This patch introduces remote memcg charging API which the
producer can use to charge the allocations to the memcg of the listener.

There are seven fsnotify kmem caches and among them allocations from
dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and
inotify_inode_mark_cachep happens in the context of syscall from the
listener. So, SLAB_ACCOUNT is enough for these caches.

The objects from fsnotify_mark_connector_cachep are not accounted as
they are small compared to the notification mark or events and it is
unclear whom to account connector to since it is shared by all events
attached to the inode.

The allocations from the event caches happen in the context of the event
producer. For such caches we will need to remote charge the allocations
to the listener's memcg. Thus we save the memcg reference in the
fsnotify_group structure of the listener.

This patch has also moved the members of fsnotify_group to keep the size
same, at least for 64 bit build, even with additional member by filling
the holes.

[shakeelb@google.com: use GFP_KERNEL_ACCOUNT rather than open-coding it]
Link: http://lkml.kernel.org/r/20180702215439.211597-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: factor out helpers to add/remove mark

Factor out helpers fanotify_add_mark() and fanotify_remove_mark()
to reduce duplicated code.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: add helper to get mask from connector

Use a helper to get the mask from the object (i.e. i_fsnotify_mask)
to generalize code of add/remove inode/vfsmount mark.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: pass connp and object type to fsnotify_add_mark()

Instead of passing inode and vfsmount arguments to fsnotify_add_mark()
and its _locked variant, pass an abstract object pointer and the object
type.

The helpers fsnotify_obj_{inode,mount} are added to get the concrete
object pointer from abstract object pointer.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: add do_fanotify_mark() helper; remove in-kernel call to syscall

Using the fs-internal do_fanotify_mark() helper allows us to get rid of
the fs-internal call to the sys_fanotify_mark() 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

Acked-by: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

fanotify: Avoid lost events due to ENOMEM for unlimited queues

Fanotify queues of unlimited length do not expect events can be lost.
Since these queues are used for system auditing and other security
related tasks, loosing events can even have security implications.
Currently, since the allocation is small (32-bytes), it cannot fail
however when we start accounting events in memcgs, allocation can start
failing. So avoid loosing events due to failure to allocate memory by
making event allocation use __GFP_NOFAIL.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

vfs: do bulk POLL* -> EPOLL* replacement

This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do. But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.

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

fs: annotate ->poll() instances

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

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>

fanotify: clean up CONFIG_FANOTIFY_ACCESS_PERMISSIONS ifdefs

The only negative from this patch should be an addition of 32bytes to
'struct fsnotify_group' if CONFIG_FANOTIFY_ACCESS_PERMISSIONS is not
defined.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>

audit: Record fanotify access control decisions

The fanotify interface allows user space daemons to make access
control decisions. Under common criteria requirements, we need to
optionally record decisions based on policy. This patch adds a bit mask,
FAN_AUDIT, that a user space daemon can 'or' into the response decision
which will tell the kernel that it made a decision and record it.

It would be used something like this in user space code:

response.response = FAN_DENY | FAN_AUDIT;
write(fd, &response, sizeof(struct fanotify_response));

When the syscall ends, the audit system will record the decision as a
AUDIT_FANOTIFY auxiliary record to denote that the reason this event
occurred is the result of an access control decision from fanotify
rather than DAC or MAC policy.

A sample event looks like this:

type=PATH msg=audit(1504310584.332:290): item=0 name="./evil-ls"
inode=1319561 dev=fc:03 mode=0100755 ouid=1000 ogid=1000 rdev=00:00
obj=unconfined_u:object_r:user_home_t:s0 nametype=NORMAL
type=CWD msg=audit(1504310584.332:290): cwd="/home/sgrubb"
type=SYSCALL msg=audit(1504310584.332:290): arch=c000003e syscall=2
success=no exit=-1 a0=32cb3fca90 a1=0 a2=43 a3=8 items=1 ppid=901
pid=959 auid=1000 uid=1000 gid=1000 euid=1000 suid=1000
fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts1 ses=3 comm="bash"
exe="/usr/bin/bash" subj=unconfined_u:unconfined_r:unconfined_t:
s0-s0:c0.c1023 key=(null)
type=FANOTIFY msg=audit(1504310584.332:290): resp=2

Prior to using the audit flag, the developer needs to call
fanotify_init or'ing in FAN_ENABLE_AUDIT to ensure that the kernel
supports auditing. The calling process must also have the CAP_AUDIT_WRITE
capability.

Signed-off-by: sgrubb <sgrubb@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: don't expose EOPENSTALE to userspace

When delivering an event to userspace for a file on an NFS share,
if the file is deleted on server side before user reads the event,
user will not get the event.

If the event queue contained several events, the stale event is
quietly dropped and read() returns to user with events read so far
in the buffer.

If the event queue contains a single stale event or if the stale
event is a permission event, read() returns to user with the kernel
internal error code 518 (EOPENSTALE), which is not a POSIX error code.

Check the internal return value -EOPENSTALE in fanotify_read(), just
the same as it is checked in path_openat() and drop the event in the
cases that it is not already dropped.

This is a reproducer from Marko Rauhamaa:

Just take the example program listed under "man fanotify" ("fantest")
and follow these steps:

==============================================================
NFS Server NFS Client(1) NFS Client(2)
==============================================================
# echo foo >/nfsshare/bar.txt
# cat /nfsshare/bar.txt
foo
# ./fantest /nfsshare
Press enter key to terminate.
Listening for events.
# rm -f /nfsshare/bar.txt
# cat /nfsshare/bar.txt
read: Unknown error 518
cat: /nfsshare/bar.txt: Operation not permitted
==============================================================

where NFS Client (1) and (2) are two terminal sessions on a single NFS
Client machine.

Reported-by: Marko Rauhamaa <marko.rauhamaa@f-secure.com>
Tested-by: Marko Rauhamaa <marko.rauhamaa@f-secure.com>
Cc: <linux-api@vger.kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Move ->free_mark callback to fsnotify_ops

Pointer to ->free_mark callback unnecessarily occupies one long in each
fsnotify_mark although they are the same for all marks from one
notification group. Move the callback pointer to fsnotify_ops.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Add group pointer in fsnotify_init_mark()

Currently we initialize mark->group only in fsnotify_add_mark_lock().
However we will need to access fsnotify_ops of corresponding group from
fsnotify_put_mark() so we need mark->group initialized earlier. Do that
in fsnotify_init_mark() which has a consequence that once
fsnotify_init_mark() is called on a mark, the mark has to be destroyed
by fsnotify_put_mark().

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Remove fsnotify_find_{inode|vfsmount}_mark()

These are very thin wrappers, just remove them. Drop
fs/notify/vfsmount_mark.c as it is empty now.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Remove fsnotify_recalc_{inode|vfsmount}_mask()

These helpers are just very thin wrappers now. Remove them.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Remove fsnotify_set_mark_{,ignored_}mask_locked()

These helpers are now only a simple assignment and just obfuscate
what is going on. Remove them.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Move recalculation of inode / vfsmount mask under mark_mutex

Move recalculation of inode / vfsmount notification mask under
group->mark_mutex of the mark which was modified. These are the only
places where mask recalculation happens without mark being protected
from detaching from inode / vfsmount which will cause issues with the
following patches.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>

Fix up affected files that include this signal functionality via sched.h.

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>

fsnotify: clean up spinlock assertions

Use assert_spin_locked() macro instead of hand-made BUG_ON statements.

Link: http://lkml.kernel.org/r/1474537439-18919-1-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Suggested-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: use notification_lock instead of access_lock

Fanotify code has its own lock (access_lock) to protect a list of events
waiting for a response from userspace.

However this is somewhat awkward as the same list_head in the event is
protected by notification_lock if it is part of the notification queue
and by access_lock if it is part of the fanotify private queue which
makes it difficult for any reliable checks in the generic code. So make
fanotify use the same lock - notification_lock - for protecting its
private event list.

Link: http://lkml.kernel.org/r/1473797711-14111-6-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
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>

fsnotify: convert notification_mutex to a spinlock

notification_mutex is used to protect the list of pending events. As such
there's no reason to use a sleeping lock for it. Convert it to a
spinlock.

[jack@suse.cz: fixed version]
Link: http://lkml.kernel.org/r/1474031567-1831-1-git-send-email-jack@suse.cz
Link: http://lkml.kernel.org/r/1473797711-14111-5-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
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>

fsnotify: drop notification_mutex before destroying event

fsnotify_flush_notify() and fanotify_release() destroy notification
event while holding notification_mutex.

The destruction of fanotify event includes a path_put() call which may
end up calling into a filesystem to delete an inode if we happen to be
the last holders of dentry reference which happens to be the last holder
of inode reference.

That in turn may violate lock ordering for some filesystems since
notification_mutex is also acquired e. g. during write when generating
fanotify event.

Also this is the only thing that forces notification_mutex to be a
sleeping lock. So drop notification_mutex before destroying a
notification event.

Link: http://lkml.kernel.org/r/1473797711-14111-4-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Eric Paris <eparis@redhat.com>
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>

fanotify: fix list corruption in fanotify_get_response()

fanotify_get_response() calls fsnotify_remove_event() when it finds that
group is being released from fanotify_release() (bypass_perm is set).

However the event it removes need not be only in the group's notification
queue but it can have already moved to access_list (userspace read the
event before closing the fanotify instance fd) which is protected by a
different lock. Thus when fsnotify_remove_event() races with
fanotify_release() operating on access_list, the list can get corrupted.

Fix the problem by moving all the logic removing permission events from
the lists to one place - fanotify_release().

Fixes: 5838d4442bd5 ("fanotify: fix double free of pending permission events")
Link: http://lkml.kernel.org/r/1473797711-14111-3-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: get rid of fsnotify_destroy_mark_locked()

fsnotify_destroy_mark_locked() is subtle to use because it temporarily
releases group->mark_mutex. To avoid future problems with this
function, split it into two.

fsnotify_detach_mark() is the part that needs group->mark_mutex and
fsnotify_free_mark() is the part that must be called outside of
group->mark_mutex. This way it's much clearer what's going on and we
also avoid some pointless acquisitions of group->mark_mutex.

Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: don't set FAN_ONDIR implicitly on a marks ignored mask

Currently FAN_ONDIR is always set on a mark's ignored mask when the
event mask is extended without FAN_MARK_ONDIR being set. This may
result in events for directories being ignored unexpectedly for call
sequences like

fanotify_mark(fd, FAN_MARK_ADD, FAN_OPEN | FAN_ONDIR , AT_FDCWD, "dir");
fanotify_mark(fd, FAN_MARK_ADD, FAN_CLOSE, AT_FDCWD, "dir");

Also FAN_MARK_ONDIR is only honored when adding events to a mark's mask,
but not for event removal. Fix both issues by not setting FAN_ONDIR
implicitly on the ignore mask any more. Instead treat FAN_ONDIR as any
other event flag and require FAN_MARK_ONDIR to be set by the user for
both event mask and ignore mask. Furthermore take FAN_MARK_ONDIR into
account when set for event removal.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: don't recalculate a marks mask if only the ignored mask changed

If removing bits from a mark's ignored mask, the concerning
inodes/vfsmounts mask is not affected. So don't recalculate it.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: only destroy mark when both mask and ignored_mask are cleared

In fanotify_mark_remove_from_mask() a mark is destroyed if only one of
both bitmasks (mask or ignored_mask) of a mark is cleared. However the
other mask may still be set and contain information that should not be
lost. So only destroy a mark if both masks are cleared.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched, fanotify: Deal with nested sleeps

As per e23738a7300a ("sched, inotify: Deal with nested sleeps").

fanotify_read is a wait loop with sleeps in. Wait loops rely on
task_struct::state and sleeps do too, since that's the only means of
actually sleeping. Therefore the nested sleeps destroy the wait loop
state and the wait loop breaks the sleep functions that assume
TASK_RUNNING (mutex_lock).

Fix this by using the new woken_wake_function and wait_woken() stuff,
which registers wakeups in wait and thereby allows shrinking the
task_state::state changes to the actual sleep part.

Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Paris <eparis@redhat.com>
Link: http://lkml.kernel.org/r/20141216152838.GZ3337@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

fanotify: enable close-on-exec on events' fd when requested in fanotify_init()

According to commit 80af258867648 ("fanotify: groups can specify their
f_flags for new fd"), file descriptors created as part of file access
notification events inherit flags from the event_f_flags argument passed
to syscall fanotify_init(2)[1].

Unfortunately O_CLOEXEC is currently silently ignored.

Indeed, event_f_flags are only given to dentry_open(), which only seems to
care about O_ACCMODE and O_PATH in do_dentry_open(), O_DIRECT in
open_check_o_direct() and O_LARGEFILE in generic_file_open().

It's a pity, since, according to some lookup on various search engines and
http://codesearch.debian.net/, there's already some userspace code which
use O_CLOEXEC:

- in systemd's readahead[2]:

fanotify_fd = fanotify_init(FAN_CLOEXEC|FAN_NONBLOCK, O_RDONLY|O_LARGEFILE|O_CLOEXEC|O_NOATIME);

- in clsync[3]:

#define FANOTIFY_EVFLAGS (O_LARGEFILE|O_RDONLY|O_CLOEXEC)

int fanotify_d = fanotify_init(FANOTIFY_FLAGS, FANOTIFY_EVFLAGS);

- in examples [4] from "Filesystem monitoring in the Linux
kernel" article[5] by Aleksander Morgado:

if ((fanotify_fd = fanotify_init (FAN_CLOEXEC,
O_RDONLY | O_CLOEXEC | O_LARGEFILE)) < 0)

Additionally, since commit 48149e9d3a7e ("fanotify: check file flags
passed in fanotify_init"). having O_CLOEXEC as part of fanotify_init()
second argument is expressly allowed.

So it seems expected to set close-on-exec flag on the file descriptors if
userspace is allowed to request it with O_CLOEXEC.

But Andrew Morton raised[6] the concern that enabling now close-on-exec
might break existing applications which ask for O_CLOEXEC but expect the
file descriptor to be inherited across exec().

In the other hand, as reported by Mihai Dontu[7] close-on-exec on the file
descriptor returned as part of file access notify can break applications
due to deadlock. So close-on-exec is needed for most applications.

More, applications asking for close-on-exec are likely expecting it to be
enabled, relying on O_CLOEXEC being effective. If not, it might weaken
their security, as noted by Jan Kara[8].

So this patch replaces call to macro get_unused_fd() by a call to function
get_unused_fd_flags() with event_f_flags value as argument. This way
O_CLOEXEC flag in the second argument of fanotify_init(2) syscall is
interpreted and close-on-exec get enabled when requested.

[1] http://man7.org/linux/man-pages/man2/fanotify_init.2.html
[2] http://cgit.freedesktop.org/systemd/systemd/tree/src/readahead/readahead-collect.c?id=v208#n294
[3] https://github.com/xaionaro/clsync/blob/v0.2.1/sync.c#L1631
https://github.com/xaionaro/clsync/blob/v0.2.1/configuration.h#L38
[4] http://www.lanedo.com/~aleksander/fanotify/fanotify-example.c
[5] http://www.lanedo.com/2013/filesystem-monitoring-linux-kernel/
[6] http://lkml.kernel.org/r/20141001153621.65e9258e65a6167bf2e4cb50@linux-foundation.org
[7] http://lkml.kernel.org/r/20141002095046.3715eb69@mdontu-l
[8] http://lkml.kernel.org/r/20141002104410.GB19748@quack.suse.cz

Link: http://lkml.kernel.org/r/cover.1411562410.git.ydroneaud@opteya.com
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Mihai Don\u021bu <mihai.dontu@gmail.com>
Cc: Pádraig Brady <P@draigBrady.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Michael Kerrisk-manpages <mtk.manpages@gmail.com>
Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Richard Guy Briggs <rgb@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Michael Kerrisk <mtk.manpages@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>

fanotify: fix double free of pending permission events

Commit 85816794240b ("fanotify: Fix use after free for permission
events") introduced a double free issue for permission events which are
pending in group's notification queue while group is being destroyed.
These events are freed from fanotify_handle_event() but they are not
removed from groups notification queue and thus they get freed again
from fsnotify_flush_notify().

Fix the problem by removing permission events from notification queue
before freeing them if we skip processing access response. Also expand
comments in fanotify_release() to explain group shutdown in detail.

Fixes: 85816794240b9659e66e4d9b0df7c6e814e5f603
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Douglas Leeder <douglas.leeder@sophos.com>
Tested-by: Douglas Leeder <douglas.leeder@sophos.com>
Reported-by: Heinrich Schuchard <xypron.glpk@gmx.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: rename event handling functions

Rename fsnotify_add_notify_event() to fsnotify_add_event() since the
"notify" part is duplicit. Rename fsnotify_remove_notify_event() and
fsnotify_peek_notify_event() to fsnotify_remove_first_event() and
fsnotify_peek_first_event() respectively since "notify" part is duplicit
and they really look at the first event in the queue.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: check file flags passed in fanotify_init

Without this patch fanotify_init does not validate the value passed in
event_f_flags.

When a fanotify event is read from the fanotify file descriptor a new
file descriptor is created where file.f_flags = event_f_flags.

Internal and external open flags are stored together in field f_flags of
struct file. Hence, an application might create file descriptors with
internal flags like FMODE_EXEC, FMODE_NOCMTIME set.

Jan Kara and Eric Paris both aggreed that this is a bug and the value of
event_f_flags should be checked:
https://lkml.org/lkml/2014/4/29/522
https://lkml.org/lkml/2014/4/29/539

This updated patch version considers the comments by Michael Kerrisk in
https://lkml.org/lkml/2014/5/4/10

With the patch the value of event_f_flags is checked.
When specifying an invalid value error EINVAL is returned.

Internal flags are disallowed.

File creation flags are disallowed:
O_CREAT, O_DIRECTORY, O_EXCL, O_NOCTTY, O_NOFOLLOW, O_TRUNC, and O_TTY_INIT.

Flags which do not make sense with fanotify are disallowed:
__O_TMPFILE, O_PATH, FASYNC, and O_DIRECT.

This leaves us with the following allowed values:

O_RDONLY, O_WRONLY, O_RDWR are basic functionality. The are stored in the
bits given by O_ACCMODE.

O_APPEND is working as expected. The value might be useful in a logging
application which appends the current status each time the log is opened.

O_LARGEFILE is needed for files exceeding 4GB on 32bit systems.

O_NONBLOCK may be useful when monitoring slow devices like tapes.

O_NDELAY is equal to O_NONBLOCK except for platform parisc.
To avoid code breaking on parisc either both flags should be
allowed or none. The patch allows both.

__O_SYNC and O_DSYNC may be used to avoid data loss on power disruption.

O_NOATIME may be useful to reduce disk activity.

O_CLOEXEC may be useful, if separate processes shall be used to scan files.

Once this patch is accepted, the fanotify_init.2 manpage has to be updated.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/notify/fanotify/fanotify_user.c: fix FAN_MARK_FLUSH flag checking

If fanotify_mark is called with illegal value of arguments flags and
marks it usually returns EINVAL.

When fanotify_mark is called with FAN_MARK_FLUSH the argument flags is
not checked for irrelevant flags like FAN_MARK_IGNORED_MASK.

The patch removes this inconsistency.

If an irrelevant flag is set error EINVAL is returned.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: FAN_MARK_FLUSH: avoid having to provide a fake/invalid fd and path

Originally from Tvrtko Ursulin (https://lkml.org/lkml/2011/1/12/112)

Avoid having to provide a fake/invalid fd and path when flushing marks

Currently for a group to flush marks it has set it needs to provide a
fake or invalid (but resolvable) file descriptor and path when calling
fanotify_mark. This patch pulls the flush handling a bit up so file
descriptor and path are completely ignored when flushing.

I reworked the patch to be applicable again (the signature of
fanotify_mark has changed since Tvrtko's work).

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Tvrtko Ursulin <tvrtko.ursulin@onelan.co.uk>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: fix -EOVERFLOW with large files on 64-bit

On 64-bit systems, O_LARGEFILE is automatically added to flags inside
the open() syscall (also openat(), blkdev_open(), etc). Userspace
therefore defines O_LARGEFILE to be 0 - you can use it, but it's a
no-op. Everything should be O_LARGEFILE by default.

But: when fanotify does create_fd() it uses dentry_open(), which skips
all that. And userspace can't set O_LARGEFILE in fanotify_init()
because it's defined to 0. So if fanotify gets an event regarding a
large file, the read() will just fail with -EOVERFLOW.

This patch adds O_LARGEFILE to fanotify_init()'s event_f_flags on 64-bit
systems, using the same test as open()/openat()/etc.

Addresses https://bugzilla.redhat.com/show_bug.cgi?id=696821

Signed-off-by: Will Woods <wwoods@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: move unrelated handling from copy_event_to_user()

Move code moving event structure to access_list from copy_event_to_user()
to fanotify_read() where it is more logical (so that we can immediately
see in the main loop that we either move the event to a different list
or free it). Also move special error handling for permission events
from copy_event_to_user() to the main loop to have it in one place with
error handling for normal events. This makes copy_event_to_user()
really only copy the event to user without any side effects.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
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>

fanotify: reorganize loop in fanotify_read()

Swap the error / "read ok" branches in the main loop of fanotify_read().
We will grow the "read ok" part in the next patch and this makes the
indentation easier. Also it is more common to have error conditions
inside an 'if' instead of the fast path.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
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>

fanotify: convert access_mutex to spinlock

access_mutex is used only to guard operations on access_list. There's
no need for sleeping within this lock so just make a spinlock out of it.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
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>

fanotify: use fanotify event structure for permission response processing

Currently, fanotify creates new structure to track the fact that
permission event has been reported to userspace and someone is waiting
for a response to it. As event structures are now completely in the
hands of each notification framework, we can use the event structure for
this tracking instead of allocating a new structure.

Since this makes the event structures for normal events and permission
events even more different and the structures have different lifetime
rules, we split them into two separate structures (where permission
event structure contains the structure for a normal event). This makes
normal events 8 bytes smaller and the code a tad bit cleaner.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: remove useless bypass_perm check

The prepare_for_access_response() function checks whether
group->fanotify_data.bypass_perm is set. However this test can never be
true because prepare_for_access_response() is called only from
fanotify_read() which means fanotify group is alive with an active fd
while bypass_perm is set from fanotify_release() when all file
descriptors pointing to the group are closed and the group is going
away.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
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>

fsnotify: Allocate overflow events with proper type

Commit 7053aee26a35 "fsnotify: do not share events between notification
groups" used overflow event statically allocated in a group with the
size of the generic notification event. This causes problems because
some code looks at type specific parts of event structure and gets
confused by a random data it sees there and causes crashes.

Fix the problem by allocating overflow event with type corresponding to
the group type so code cannot get confused.

Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Fix use after free for permission events

Currently struct fanotify_event_info has been destroyed immediately
after reporting its contents to userspace. However that is wrong for
permission events because those need to stay around until userspace
provides response which is filled back in fanotify_event_info. So change
to code to free permission events only after we have got the response
from userspace.

Reported-and-tested-by: Jiri Kosina <jkosina@suse.cz>
Reported-and-tested-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: Jan Kara <jack@suse.cz>

compat: fix sys_fanotify_mark

Commit 91c2e0bcae72 ("unify compat fanotify_mark(2), switch to
COMPAT_SYSCALL_DEFINE") added a new unified compat fanotify_mark syscall
to be used by all architectures.

Unfortunately the unified version merges the split mask parameter in a
wrong way: the lower and higher word got swapped.

This was discovered with glibc's tst-fanotify test case.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reported-by: Andreas Krebbel <krebbel@linux.vnet.ibm.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Acked-by: "David S. Miller" <davem@davemloft.net>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: <stable@vger.kernel.org> [3.10+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: do not share events between notification groups

Currently fsnotify framework creates one event structure for each
notification event and links this event into all interested notification
groups. This is done so that we save memory when several notification
groups are interested in the event. However the need for event
structure shared between inotify & fanotify bloats the event structure
so the result is often higher memory consumption.

Another problem is that fsnotify framework keeps path references with
outstanding events so that fanotify can return open file descriptors
with its events. This has the undesirable effect that filesystem cannot
be unmounted while there are outstanding events - a regression for
inotify compared to a situation before it was converted to fsnotify
framework. For fanotify this problem is hard to avoid and users of
fanotify should kind of expect this behavior when they ask for file
descriptors from notified files.

This patch changes fsnotify and its users to create separate event
structure for each group. This allows for much simpler code (~400 lines
removed by this patch) and also smaller event structures. For example
on 64-bit system original struct fsnotify_event consumes 120 bytes, plus
additional space for file name, additional 24 bytes for second and each
subsequent group linking the event, and additional 32 bytes for each
inotify group for private data. After the conversion inotify event
consumes 48 bytes plus space for file name which is considerably less
memory unless file names are long and there are several groups
interested in the events (both of which are uncommon). Fanotify event
fits in 56 bytes after the conversion (fanotify doesn't care about file
names so its events don't have to have it allocated). A win unless
there are four or more fanotify groups interested in the event.

The conversion also solves the problem with unmount when only inotify is
used as we don't have to grab path references for inotify events.

[hughd@google.com: fanotify: fix corruption preventing startup]
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: put duplicate code for adding vfsmount/inode marks into an own function

The code under the groups mark_mutex in fanotify_add_inode_mark() and
fanotify_add_vfsmount_mark() is almost identical. So put it into a
seperate function.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Eric Paris <eparis@redhat.com>
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>

fanotify: fix races when adding/removing marks

For both adding an event to an existing mark and destroying a mark we
first have to find it via fsnotify_find_[inode|vfsmount]_mark(). But
getting the mark and adding an event (or destroying it) is not done
atomically. This opens a race where a thread is about to destroy a mark
while another thread still finds the same mark and adds an event to its
mask although it will be destroyed.

Another race exists concerning the excess of a groups number of marks
limit: When a mark is added the number of group marks is checked against
the max number of marks per group and increased afterwards. Since check
and increment is also not done atomically, this may result in 2 or more
processes passing the check at the same time and increasing the number
of group marks above the allowed limit.

With this patch both races are avoided by doing the concerning
operations with the groups mark mutex locked.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Eric Paris <eparis@redhat.com>
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>

fanotify: info leak in copy_event_to_user()

The ->reserved field isn't cleared so we leak one byte of stack
information to userspace.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Eric Paris <eparis@redhat.com>
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>

fanotify: quit wanking with FASYNC in ->release()

... especially since there's no way to get that sucker
on the list fsnotify_fasync() works with - the only thing
adding to it is fsnotify_fasync() itself and it's never
called for fanotify files while they are opened.

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

unify compat fanotify_mark(2), switch to COMPAT_SYSCALL_DEFINE

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

teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long

... and convert a bunch of SYSCALL_DEFINE ones to SYSCALL_DEFINE<n>,
killing the boilerplate crap around them.

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

new helper: file_inode(file)

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

fs, notify: add procfs fdinfo helper

This allow us to print out fsnotify details such as watchee inode, device,
mask and optionally a file handle.

For inotify objects if kernel compiled with exportfs support the output
will be

| pos: 0
| flags: 02000000
| inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
| inotify wd:2 ino:a111 sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:11a1000020542153
| inotify wd:1 ino:6b149 sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:49b1060023552153

If kernel compiled without exportfs support, the file handle
won't be provided but inode and device only.

| pos: 0
| flags: 02000000
| inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0
| inotify wd:2 ino:a111 sdev:800013 mask:800afce ignored_mask:0
| inotify wd:1 ino:6b149 sdev:800013 mask:800afce ignored_mask:0

For fanotify the output is like

| pos: 0
| flags: 04002
| fanotify flags:10 event-flags:0
| fanotify mnt_id:12 mask:3b ignored_mask:0
| fanotify ino:50205 sdev:800013 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:05020500fb1d47e7

To minimize impact on general fsnotify code the new functionality
is gathered in fs/notify/fdinfo.c file.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Helsley <matt.helsley@gmail.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@onelan.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: make fasync generic for both inotify and fanotify

inotify is supposed to support async signal notification when information
is available on the inotify fd. This patch moves that support to generic
fsnotify functions so it can be used by all notification mechanisms.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: pass group to fsnotify_destroy_mark()

In fsnotify_destroy_mark() dont get the group from the passed mark anymore,
but pass the group itself as an additional parameter to the function.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: add an extra flag to mark_remove_from_mask that indicates wheather a mark should be destroyed

This patch adds an extra flag to mark_remove_from_mask() to inform the caller if
the mark should be destroyed.
With this we dont destroy the mark implicitly in the function itself any more
but let the caller handle it.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

inotify, fanotify: replace fsnotify_put_group() with fsnotify_destroy_group()

Currently in fsnotify_put_group() the ref count of a group is decremented and if
it becomes 0 fsnotify_destroy_group() is called. Since a groups ref count is only
at group creation set to 1 and never increased after that a call to fsnotify_put_group()
always results in a call to fsnotify_destroy_group().
With this patch fsnotify_destroy_group() is called directly.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: fix FAN_Q_OVERFLOW case of fanotify_read()

If the FAN_Q_OVERFLOW bit set in event->mask, the fanotify event
metadata will not contain a valid file descriptor, but
copy_event_to_user() didn't check for that, and unconditionally does a
fd_install() on the file descriptor.

Which in turn will cause a BUG_ON() in __fd_install().

Introduced by commit 352e3b249284 ("fanotify: sanitize failure exits in
copy_event_to_user()")

Mea culpa - missed that path ;-/

Reported-by: Alex Shi <lkml.alex@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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>

fanotify: sanitize failure exits in copy_event_to_user()

* do copy_to_user() before prepare_for_access_response(); that kills
the need in remove_access_response().
* don't do fd_install() until we are past the last possible failure
exit. Don't use sys_close() on cleanup side - just put_unused_fd()
and fput(). Less racy that way...

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

switch dentry_open() to struct path, make it grab references itself

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

vfs: move fsnotify junk to struct mount

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

Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

Remove one to many n's in a word

Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

fanotify: fill in the metadata_len field on struct fanotify_event_metadata

The fanotify_event_metadata now has a field which is supposed to
indicate the length of the metadata portion of the event. Fill in that
field as well.

Based-in-part-on-patch-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: Dont try to open a file descriptor for the overflow event

We should not try to open a file descriptor for the overflow event since this
will always fail.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: do not leak user reference on allocation failure

If fanotify_init is unable to allocate a new fsnotify group it will
return but will not drop its reference on the associated user struct.
Drop that reference on error.

Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: on group destroy allow all waiters to bypass permission check

When fanotify_release() is called, there may still be processes waiting for
access permission. Currently only processes for which an event has already been
queued into the groups access list will be woken up. Processes for which no
event has been queued will continue to sleep and thus cause a deadlock when
fsnotify_put_group() is called.
Furthermore there is a race allowing further processes to be waiting on the
access wait queue after wake_up (if they arrive before clear_marks_by_group()
is called).
This patch corrects this by setting a flag to inform processes that the group
is about to be destroyed and thus not to wait for access permission.

[additional changelog from eparis]
Lets think about the 4 relevant code paths from the PoV of the
'operator' 'listener' 'responder' and 'closer'. Where operator is the
process doing an action (like open/read) which could require permission.
Listener is the task (or in this case thread) slated with reading from
the fanotify file descriptor. The 'responder' is the thread responsible
for responding to access requests. 'Closer' is the thread attempting to
close the fanotify file descriptor.

The 'operator' is going to end up in:
fanotify_handle_event()
get_response_from_access()
(THIS BLOCKS WAITING ON USERSPACE)

The 'listener' interesting code path
fanotify_read()
copy_event_to_user()
prepare_for_access_response()
(THIS CREATES AN fanotify_response_event)

The 'responder' code path:
fanotify_write()
process_access_response()
(REMOVE A fanotify_response_event, SET RESPONSE, WAKE UP 'operator')

The 'closer':
fanotify_release()
(SUPPOSED TO CLEAN UP THE REST OF THIS MESS)

What we have today is that in the closer we remove all of the
fanotify_response_events and set a bit so no more response events are
ever created in prepare_for_access_response().

The bug is that we never wake all of the operators up and tell them to
move along. You fix that in fanotify_get_response_from_access(). You
also fix other operators which haven't gotten there yet. So I agree
that's a good fix.
[/additional changelog from eparis]

[remove additional changes to minimize patch size]
[move initialization so it was inside CONFIG_FANOTIFY_PERMISSION]

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: Dont allow a mask of 0 if setting or removing a mark

In mark_remove_from_mask() we destroy marks that have their event mask cleared.
Thus we should not allow the creation of those marks in the first place.
With this patch we check if the mask given from user is 0 in case of FAN_MARK_ADD.
If so we return an error. Same for FAN_MARK_REMOVE since this does not have any
effect.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: correct broken ref counting in case adding a mark failed

If adding a mount or inode mark failed fanotify_free_mark() is called explicitly.
But at this time the mark has already been put into the destroy list of the
fsnotify_mark kernel thread. If the thread is too slow it will try to decrease
the reference of a mark, that has already been freed by fanotify_free_mark().
(If its fast enough it will only decrease the marks ref counter from 2 to 1 - note
that the counter has been increased to 2 in add_mark() - which has practically no
effect.)

This patch fixes the ref counting by not calling free_mark() explicitly, but
decreasing the ref counter and rely on the fsnotify_mark thread to cleanup in
case adding the mark has failed.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: deny permissions when no event was sent

If no event was sent to userspace we cannot expect userspace to respond to
permissions requests. Today such requests just hang forever. This patch will
deny any permissions event which was unable to be sent to userspace.

Reported-by: Tvrtko Ursulin <tvrtko.ursulin@sophos.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

make fanotify_read() restartable across signals

In fanotify_read() return -ERESTARTSYS instead of -EINTR to
make read() restartable across signals (BSD semantic).

Signed-off-by: Eric Paris <eparis@redhat.com>

fs/notify/fanotify/fanotify_user.c: fix warnings

fs/notify/fanotify/fanotify_user.c: In function 'fanotify_release':
fs/notify/fanotify/fanotify_user.c:375: warning: unused variable 'lre'
fs/notify/fanotify/fanotify_user.c:375: warning: unused variable 're'

this is really ugly.

Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: do not recalculate the mask if the ignored mask changed

If fanotify sets a new bit in the ignored mask it will cause the generic
fsnotify layer to recalculate the real mask. This is stupid since we
didn't change that part.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: ignore events on directories unless specifically requested

fanotify has a very limited number of events it sends on directories. The
usefulness of these events is yet to be seen and still we send them. This
is particularly painful for mount marks where one might receive many of
these useless events. As such this patch will drop events on IS_DIR()
inodes unless they were explictly requested with FAN_ON_DIR.

This means that a mark on a directory without FAN_EVENT_ON_CHILD or
FAN_ON_DIR is meaningless and will result in no events ever (although it
will still be allowed since detecting it is hard)

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: limit number of listeners per user

fanotify currently has no limit on the number of listeners a given user can
have open. This patch limits the total number of listeners per user to
128. This is the same as the inotify default limit.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: allow userspace to override max marks

Some fanotify groups, especially those like AV scanners, will need to place
lots of marks, particularly ignore marks. Since ignore marks do not pin
inodes in cache and are cleared if the inode is removed from core (usually
under memory pressure) we expose an interface for listeners, with
CAP_SYS_ADMIN, to override the maximum number of marks and be allowed to
set and 'unlimited' number of marks. Programs which make use of this
feature will be able to OOM a machine.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: limit the number of marks in a single fanotify group

There is currently no limit on the number of marks a given fanotify group
can have. Since fanotify is gated on CAP_SYS_ADMIN this was not seen as
a serious DoS threat. This patch implements a default of 8192, the same as
inotify to work towards removing the CAP_SYS_ADMIN gating and eliminating
the default DoS'able status.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: allow userspace to override max queue depth

fanotify has a defualt max queue depth. This patch allows processes which
explicitly request it to have an 'unlimited' queue depth. These processes
need to be very careful to make sure they cannot fall far enough behind
that they OOM the box. Thus this flag is gated on CAP_SYS_ADMIN.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: implement a default maximum queue depth

Currently fanotify has no maximum queue depth. Since fanotify is
CAP_SYS_ADMIN only this does not pose a normal user DoS issue, but it
certianly is possible that an fanotify listener which can't keep up could
OOM the box. This patch implements a default 16k depth. This is the same
default depth used by inotify, but given fanotify's better queue merging in
many situations this queue will contain many additional useful events by
comparison.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: ignore fanotify ignore marks if open writers

fanotify will clear ignore marks if a task changes the contents of an
inode. The problem is with the races around when userspace finishes
checking a file and when that result is actually attached to the inode.
This race was described as such:

Consider the following scenario with hostile processes A and B, and
victim process C:
1. Process A opens new file for writing. File check request is generated.
2. File check is performed in userspace. Check result is "file has no malware".
3. The "permit" response is delivered to kernel space.
4. File ignored mark set.
5. Process A writes dummy bytes to the file. File ignored flags are cleared.
6. Process B opens the same file for reading. File check request is generated.
7. File check is performed in userspace. Check result is "file has no malware".
8. Process A writes malware bytes to the file. There is no cached response yet.
9. The "permit" response is delivered to kernel space and is cached in fanotify.
10. File ignored mark set.
11. Now any process C will be permitted to open the malware file.
There is a race between steps 8 and 10

While fanotify makes no strong guarantees about systems with hostile
processes there is no reason we cannot harden against this race. We do
that by simply ignoring any ignore marks if the inode has open writers (aka
i_writecount > 0). (We actually do not ignore ignore marks if the
FAN_MARK_SURV_MODIFY flag is set)

Reported-by: Vasily Novikov <vasily.novikov@kaspersky.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: implement fanotify listener ordering

The fanotify listeners needs to be able to specify what types of operations
they are going to perform so they can be ordered appropriately between other
listeners doing other types of operations. They need this to be able to make
sure that things like hierarchichal storage managers will get access to inodes
before processes which need the data. This patch defines 3 possible uses
which groups must indicate in the fanotify_init() flags.

FAN_CLASS_PRE_CONTENT
FAN_CLASS_CONTENT
FAN_CLASS_NOTIF

Groups will receive notification in that order. The order between 2 groups in
the same class is undeterministic.

FAN_CLASS_PRE_CONTENT is intended to be used by listeners which need access to
the inode before they are certain that the inode contains it's final data. A
hierarchical storage manager should choose to use this class.

FAN_CLASS_CONTENT is intended to be used by listeners which need access to the
inode after it contains its intended contents. This would be the appropriate
level for an AV solution or document control system.

FAN_CLASS_NOTIF is intended for normal async notification about access, much the
same as inotify and dnotify. Syncronous permissions events are not permitted
at this class.

Signed-off-by: Eric Paris <eparis@redhat.com>

llseek: automatically add .llseek fop

All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.

The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.

New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time. Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.

The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.

Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.

Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.

===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
// but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}

@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
*off = E
|
*off += E
|
func(..., off, ...)
|
E = *off
)
...+>
}

@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}

@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
*off = E
|
*off += E
|
func(..., off, ...)
|
E = *off
)
...+>
}

@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}

@ fops0 @
identifier fops;
@@
struct file_operations fops = {
...
};

@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
.llseek = llseek_f,
...
};

@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
.read = read_f,
...
};

@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
.write = write_f,
...
};

@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
.open = open_f,
...
};

// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
... .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};

@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
... .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};

// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
... .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};

// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};

// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};

@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+ .llseek = default_llseek, /* write accesses f_pos */
};

// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////

@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
.write = write_f,
.read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};

@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};

@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};

@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>

fanotify: Return EPERM when a process is not privileged

The appropriate error code when privileged operations are denied is
EPERM, not EACCES.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <paris@paris.rdu.redhat.com>

fanotify: flush outstanding perm requests on group destroy

When an fanotify listener is closing it may cause a deadlock between the
listener and the original task doing an fs operation. If the original task
is waiting for a permissions response it will be holding the srcu lock. The
listener cannot clean up and exit until after that srcu lock is syncronized.
Thus deadlock. The fix introduced here is to stop accepting new permissions
events when a listener is shutting down and to grant permission for all
outstanding events. Thus the original task will eventually release the srcu
lock and the listener can complete shutdown.

Reported-by: Andreas Gruenbacher <agruen@suse.de>
Cc: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

Revert "fsnotify: store struct file not struct path"

This reverts commit 3bcf3860a4ff9bbc522820b4b765e65e4deceb3e (and the
accompanying commit c1e5c954020e "vfs/fsnotify: fsnotify_close can delay
the final work in fput" that was a horribly ugly hack to make it work at
all).

The 'struct file' approach not only causes that disgusting hack, it
somehow breaks pulseaudio, probably due to some other subtlety with
f_count handling.

Fix up various conflicts due to later fsnotify work.

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

fsnotify: remove group->mask

group->mask is now useless. It was originally a shortcut for fsnotify to
save on performance. These checks are now redundant, so we remove them.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: store struct file not struct path

Al explains that calling dentry_open() with a mnt/dentry pair is only
garunteed to be safe if they are already used in an open struct file. To
make sure this is the case don't store and use a struct path in fsnotify,
always use a struct file.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: groups can specify their f_flags for new fd

Currently fanotify fds opened for thier listeners are done with f_flags
equal to O_RDONLY | O_LARGEFILE. This patch instead takes f_flags from the
fanotify_init syscall and uses those when opening files in the context of
the listener.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: update gfp/slab.h includes

Implicit slab.h inclusion via percpu.h is about to go away. Make sure
gfp.h or slab.h is included as necessary.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: drop the useless priority argument

The priority argument in fanotify is useless. Kill it.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: do not return 0 in a void function

remove_access_response() is supposed to have a void return, but was
returning 0;

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: userspace interface for permission responses

fanotify groups need to respond to events which include permissions types.
To do so groups will send a response using write() on the fanotify_fd they
have open.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: permissions and blocking

This is the backend work needed for fanotify to support the new
FS_OPEN_PERM and FS_ACCESS_PERM fsnotify events. This is done using the
new fsnotify secondary queue. No userspace interface is provided actually
respond to or request these events.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: add group priorities

This introduces an ordering to fsnotify groups. With purely asynchronous
notification based "things" implementing fsnotify (inotify, dnotify) ordering
isn't particularly important. But if people want to use fsnotify for the
basis of sycronous notification or blocking notification ordering becomes
important.

eg. A Hierarchical Storage Management listener would need to get its event
before an AV scanner could get its event (since the HSM would need to
bring the data in for the AV scanner to scan.) Typically asynchronous notification
would want to run after the AV scanner made any relevant access decisions
so as to not send notification about an event that was denied.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: clear all fanotify marks

fanotify listeners may want to clear all marks. They may want to do this
to destroy all of their inode marks which have nothing but ignores.
Realistically this is useful for av vendors who update policy and want to
clear all of their cached allows.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: allow ignored_masks to survive modify

Some users may want to truely ignore an inode even if it has been modified.
Say you are wanting a mount which contains a log file and you really don't
want any notification about that file. This patch allows the listener to
do that.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: allow users to set an ignored_mask

Change the sys_fanotify_mark() system call so users can set ignored_masks
on inodes. Remember, if a user new sets a real mask, and only sets ignored
masks, the ignore will never be pinned in memory. Thus ignored_masks can
be lost under memory pressure and the user may again get events they
previously thought were ignored.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: allow marks to not pin inodes in core

inotify marks must pin inodes in core. dnotify doesn't technically need to
since they are closed when the directory is closed. fanotify also need to
pin inodes in core as it works today. But the next step is to introduce
the concept of 'ignored masks' which is actually a mask of events for an
inode of no interest. I claim that these should be liberally sent to the
kernel and should not pin the inode in core. If the inode is brought back
in the listener will get an event it may have thought excluded, but this is
not a serious situation and one any listener should deal with.

This patch lays the ground work for non-pinning inode marks by using lazy
inode pinning. We do not pin a mark until it has a non-zero mask entry. If a
listener new sets a mask we never pin the inode.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: remove outgoing function checks in fanotify.h

A number of validity checks on outgoing data are done in static inlines but
are only used in one place. Instead just do them where they are used for
readability.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: remove fanotify.h declarations

fanotify_mark_validate functions are all needlessly declared in headers as
static inlines. Instead just do the checks where they are needed for code
readability.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: split fanotify_remove_mark

split fanotify_remove_mark into fanotify_remove_inode_mark and
fanotify_remove_vfsmount_mark.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: rename FAN_MARK_ON_VFSMOUNT to FAN_MARK_MOUNT

the term 'vfsmount' isn't sensicle to userspace. instead call is 'mount.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: hooks the fanotify_mark syscall to the vfsmount code

Create a new fanotify_mark flag which indicates we should attach the mark
to the vfsmount holding the object referenced by dfd and pathname rather
than the inode itself.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: remove fanotify_add_mark

fanotify_add_mark now does nothing useful anymore, drop it.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: do not return pointer from fanotify_add_*_mark

No need to return the mark from fanotify_add_*_mark to fanotify_add_mark

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: do not call fanotify_update_object_mask in fanotify_add_mark

Recalculate masks in fanotify_add_mark, don't use
fanotify_update_object_mask. This gets us one step closers to readable
code.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: do not call fanotify_update_object_mask in fanotify_remove_mark

Recalculate masks in fanotify_remove_mark, don't use
fanotify_update_object_mask. This gets us one step closers to readable
code.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: remove fanotify_update_mark

fanotify_update_mark() doesn't do much useful; remove it.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: infrastructure to add an remove marks on vfsmounts

infrastructure work to add and remove marks on vfsmounts. This should get
every set up except wiring the functions to the syscalls.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: split generic and inode specific mark code

currently all marking is done by functions in inode-mark.c. Some of this
is pretty generic and should be instead done in a generic function and we
should only put the inode specific code in inode-mark.c

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: Add pids to events

Pass the process identifiers of the triggering processes to fanotify
listeners: this information is useful for event filtering and logging.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: create_fd cleanup

Code cleanup which does the fd creation work seperately from the userspace
metadata creation. It fits better with the other code.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: CONFIG_HAVE_SYSCALL_WRAPPERS for sys_fanotify_mark

Please note that you need the patch below in addition, otherwise the
syscall wrapper stuff won't work on those 32 bit architectures which enable
the wrappers.

When enabled the syscall wrapper defines always take long parameters and then
cast them to whatever is needed. This approach doesn't work for the 32 bit
case where the original syscall takes a long long parameter, since we would
lose the upper 32 bits.
So syscalls with 64 bit arguments are special cases wrt to syscall wrappers
and enp up in the ugliness below (see also sys_fallocate). In addition these
special cased syscall wrappers have the drawback that ftrace syscall tracing
doesn't work on them, since they don't get defined by using the usual macros.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: send events using read

Send events to userspace by reading the file descriptor from fanotify_init().
One will get blocks of data which look like:

struct fanotify_event_metadata {
__u32 event_len;
__u32 vers;
__s32 fd;
__u64 mask;
__s64 pid;
__u64 cookie;
} __attribute__ ((packed));

Simple code to retrieve and deal with events is below

while ((len = read(fan_fd, buf, sizeof(buf))) > 0) {
struct fanotify_event_metadata *metadata;

metadata = (void *)buf;
while(FAN_EVENT_OK(metadata, len)) {
[PROCESS HERE!!]
if (metadata->fd >= 0 && close(metadata->fd) != 0)
goto fail;
metadata = FAN_EVENT_NEXT(metadata, len);
}
}

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: fanotify_mark syscall implementation

NAME
fanotify_mark - add, remove, or modify an fanotify mark on a
filesystem object

SYNOPSIS
int fanotify_mark(int fanotify_fd, unsigned int flags, u64 mask,
int dfd, const char *pathname)

DESCRIPTION
fanotify_mark() is used to add remove or modify a mark on a filesystem
object. Marks are used to indicate that the fanotify group is
interested in events which occur on that object. At this point in
time marks may only be added to files and directories.

fanotify_fd must be a file descriptor returned by fanotify_init()

The flags field must contain exactly one of the following:

FAN_MARK_ADD - or the bits in mask and ignored mask into the mark
FAN_MARK_REMOVE - bitwise remove the bits in mask and ignored mark
from the mark

The following values can be OR'd into the flags field:

FAN_MARK_DONT_FOLLOW - same meaning as O_NOFOLLOW as described in open(2)
FAN_MARK_ONLYDIR - same meaning as O_DIRECTORY as described in open(2)

dfd may be any of the following:
AT_FDCWD: the object will be lookup up based on pathname similar
to open(2)

file descriptor of a directory: if pathname is not NULL the
object to modify will be lookup up similar to openat(2)

file descriptor of the final object: if pathname is NULL the
object to modify will be the object referenced by dfd

The mask is the bitwise OR of the set of events of interest such as:
FAN_ACCESS - object was accessed (read)
FAN_MODIFY - object was modified (write)
FAN_CLOSE_WRITE - object was writable and was closed
FAN_CLOSE_NOWRITE - object was read only and was closed
FAN_OPEN - object was opened
FAN_EVENT_ON_CHILD - interested in objected that happen to
children. Only relavent when the object
is a directory
FAN_Q_OVERFLOW - event queue overflowed (not implemented)

RETURN VALUE
On success, this system call returns 0. On error, -1 is
returned, and errno is set to indicate the error.

ERRORS
EINVAL An invalid value was specified in flags.

EINVAL An invalid value was specified in mask.

EINVAL An invalid value was specified in ignored_mask.

EINVAL fanotify_fd is not a file descriptor as returned by
fanotify_init()

EBADF fanotify_fd is not a valid file descriptor

EBADF dfd is not a valid file descriptor and path is NULL.

ENOTDIR dfd is not a directory and path is not NULL

EACCESS no search permissions on some part of the path

ENENT file not found

ENOMEM Insufficient kernel memory is available.

CONFORMING TO
These system calls are Linux-specific.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: sys_fanotify_mark declartion

This patch simply declares the new sys_fanotify_mark syscall

int fanotify_mark(int fanotify_fd, unsigned int flags, u64_mask,
int dfd const char *pathname)

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: fanotify_init syscall implementation

NAME
fanotify_init - initialize an fanotify group

SYNOPSIS
int fanotify_init(unsigned int flags, unsigned int event_f_flags, int priority);

DESCRIPTION
fanotify_init() initializes a new fanotify instance and returns a file
descriptor associated with the new fanotify event queue.

The following values can be OR'd into the flags field:

FAN_NONBLOCK Set the O_NONBLOCK file status flag on the new open file description.
Using this flag saves extra calls to fcntl(2) to achieve the same
result.

FAN_CLOEXEC Set the close-on-exec (FD_CLOEXEC) flag on the new file descriptor.
See the description of the O_CLOEXEC flag in open(2) for reasons why
this may be useful.

The event_f_flags argument is unused and must be set to 0

The priority argument is unused and must be set to 0

RETURN VALUE
On success, this system call return a new file descriptor. On error, -1 is
returned, and errno is set to indicate the error.

ERRORS
EINVAL An invalid value was specified in flags.

EINVAL A non-zero valid was passed in event_f_flags or in priority

ENFILE The system limit on the total number of file descriptors has been reached.

ENOMEM Insufficient kernel memory is available.

CONFORMING TO
These system calls are Linux-specific.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: fanotify_init syscall declaration

This patch defines a new syscall fanotify_init() of the form:

int sys_fanotify_init(unsigned int flags, unsigned int event_f_flags,
unsigned int priority)

This syscall is used to create and fanotify group. This is very similar to
the inotify_init() syscall.

Signed-off-by: Eric Paris <eparis@redhat.com>