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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_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>
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: f644bc449b ("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>
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Merge tag 'fsnotify_for_v5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull fsnotify fixes from Jan Kara:
"Fixes for userspace breakage caused by fsnotify changes ~3 years ago
and one fanotify cleanup"
* tag 'fsnotify_for_v5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
fsnotify: fix fsnotify hooks in pseudo filesystems
fsnotify: invalidate dcache before IN_DELETE event
fanotify: remove variable set but not used
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>
The code that uses the pointer info has been removed in 7326e382c2
("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>
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>
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>
We do not want to report the dirfid+name of a directory whose
inode/sb are not watched, because watcher may not have permissions
to see the directory content.
Use an internal iter_info to indicate to fanotify_alloc_event()
which marks of this group are watching FAN_RENAME, so it can decide
if we need to record only the old parent+name, new parent+name or both.
Link: https://lore.kernel.org/r/20211129201537.1932819-10-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
[JK: Modified code to pass around only mask of mark types matching
generated event]
Signed-off-by: Jan Kara <jack@suse.cz>
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_info buffer is parceled into variable sized records, so the
records must be written in order: dir_fh, file_fh, name.
Use helpers to assert that order and make fanotify_alloc_name_event()
a bit more generic to allow empty dir_fh record and to allow expanding
to more records (i.e. name2) soon.
Link: https://lore.kernel.org/r/20211129201537.1932819-7-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The fanotify_info buffer contains up to two file handles and a name.
Use macros to simplify the code that access the different items within
the buffer.
Add assertions to verify that stored fh len and name len do not overflow
the u8 stored value in fanotify_info header.
Remove the unused fanotify_info_len() helper.
Link: https://lore.kernel.org/r/20211129201537.1932819-6-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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>
They are two different types that use the same enum, so this confusing.
Use the object type to indicate the type of object mark is attached to
and the iter type to indicate the type of watch.
A group can have two different watches of the same object type (parent
and child watches) that match the same event.
Link: https://lore.kernel.org/r/20211129201537.1932819-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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>
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>
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>
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>
struct fanotify_error_event, at least, is preallocated and isn't able to
to handle arbitrarily large file handles. Future-proof the code by
complaining loudly if a handle larger than MAX_HANDLE_SZ is ever found.
Link: https://lore.kernel.org/r/20211025192746.66445-26-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>
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_error_event would duplicate this sequence of declarations that
already exist elsewhere with a slight different size. Create a helper
macro to avoid code duplication.
Link: https://lore.kernel.org/r/20211025192746.66445-23-krisman@collabora.com
Suggested-by: Jan Kara <jack@suse.cz>
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>
Error events (FAN_FS_ERROR) against the same file system can be merged
by simply iterating the error count. The hash is taken from the fsid,
without considering the FH. This means that only the first error object
is reported.
Link: https://lore.kernel.org/r/20211025192746.66445-22-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>
Once an error event is triggered, enqueue it in the notification group,
similarly to what is done for other events. FAN_FS_ERROR is not
handled specially, since the memory is now handled by a preallocated
mempool.
For now, make the event unhashed. A future patch implements merging of
this kind of event.
Link: https://lore.kernel.org/r/20211025192746.66445-21-krisman@collabora.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>
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>
FAN_FS_ERROR allows reporting of event type FS_ERROR to userspace, which
is a mechanism to report file system wide problems via fanotify. This
commit preallocate userspace visible bits to match the FS_ERROR event.
Link: https://lore.kernel.org/r/20211025192746.66445-19-krisman@collabora.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>
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>
Instead of failing, encode an invalid file handle in fanotify_encode_fh
if no inode is provided. This bogus file handle will be reported by
FAN_FS_ERROR for non-inode errors.
Link: https://lore.kernel.org/r/20211025192746.66445-16-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>
Allow passing a NULL hash to fanotify_encode_fh and avoid calculating
the hash if not needed.
Link: https://lore.kernel.org/r/20211025192746.66445-15-krisman@collabora.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>
FAN_FS_ERROR doesn't support DFID, but this function is still called for
every event. The problem is that it is not capable of handling null
inodes, which now can happen in case of superblock error events. For
this case, just returning dir will be enough.
Link: https://lore.kernel.org/r/20211025192746.66445-14-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>
For group-wide mempool backed events, like FS_ERROR, the free_event
callback will need to reference the group's mempool to free the memory.
Wire that argument into the current callers.
Link: https://lore.kernel.org/r/20211025192746.66445-13-krisman@collabora.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>
fsnotify_add_event is growing in number of parameters, which in most
case are just passed a NULL pointer. So, split out a new
fsnotify_insert_event function to clean things up for users who don't
need an insert hook.
Link: https://lore.kernel.org/r/20211025192746.66445-10-krisman@collabora.com
Suggested-by: Amir Goldstein <amir73il@gmail.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>
Similarly to fanotify_is_perm_event and friends, provide a helper
predicate to say whether a mask is of an overflow event.
Link: https://lore.kernel.org/r/20211025192746.66445-9-krisman@collabora.com
Suggested-by: Amir Goldstein <amir73il@gmail.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>
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>
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>
Some events, like the overflow event, are not mergeable, so they are not
hashed. But, when failing inside fsnotify_add_event for lack of space,
fsnotify_add_event() still calls the insert hook, which adds the
overflow event to the merge list. Add a check to prevent any kind of
unmergeable event to be inserted in the hashtable.
Fixes: 94e00d28a6 ("fsnotify: use hash table for faster events merge")
Link: https://lore.kernel.org/r/20211025192746.66445-5-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>
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Merge tag 'fsnotify_for_v5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull fsnotify updates from Jan Kara:
"fsnotify speedups when notification actually isn't used and support
for identifying processes which caused fanotify events through pidfd
instead of normal pid"
* tag 'fsnotify_for_v5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
fsnotify: optimize the case of no marks of any type
fsnotify: count all objects with attached connectors
fsnotify: count s_fsnotify_inode_refs for attached connectors
fsnotify: replace igrab() with ihold() on attach connector
fanotify: add pidfd support to the fanotify API
fanotify: introduce a generic info record copying helper
fanotify: minor cosmetic adjustments to fid labels
kernel/pid.c: implement additional checks upon pidfd_create() parameters
kernel/pid.c: remove static qualifier from pidfd_create()
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>
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>
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>
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: 7cea2a3c50 ("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>
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>
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 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>
Event merges are expensive when event queue size is large, so limit the
linear search to 128 merge tests.
In combination with 128 size hash table, there is a potential to merge
with up to 16K events in the hashed queue.
Link: https://lore.kernel.org/r/20210304104826.3993892-6-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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>
Improve the merge key hash by mixing more values relevant for merge.
For example, all FAN_CREATE name events in the same dir used to have the
same merge key based on the dir inode. With this change the created
file name is mixed into the merge key.
The object id that was used as merge key is redundant to the event info
so it is no longer mixed into the hash.
Permission events are not hashed, so no need to hash their info.
Link: https://lore.kernel.org/r/20210304104826.3993892-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
objectid is only used by fanotify backend and it is just an optimization
for event merge before comparing all fields in event.
Move the objectid member from common struct fsnotify_event into struct
fanotify_event and reduce it to 29-bit hash to cram it together with the
3-bit event type.
Events of different types are never merged, so the combination of event
type and hash form a 32-bit key for fast compare of events.
This reduces the size of events by one pointer and paves the way for
adding hashed queue support for fanotify.
Link: https://lore.kernel.org/r/20210304104826.3993892-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
