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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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FAN_DIR_MODIFY has been enabled by commit 44d705b0370b ("fanotify:
report name info for FAN_DIR_MODIFY event") in 5.7-rc1. Now we are
planning further extensions to the fanotify API and during that we
realized that FAN_DIR_MODIFY may behave slightly differently to be more
consistent with extensions we plan. So until we finalize these
extensions, let's not bind our hands with exposing FAN_DIR_MODIFY to
userland.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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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>
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dirent modification events (create/delete/move) do not carry the
child entry name/inode information. Instead, we report FAN_ONDIR
for mkdir/rmdir so user can differentiate them from creat/unlink.
This is consistent with inotify reporting IN_ISDIR with dirent events
and is useful for implementing recursive directory tree watcher.
We avoid merging dirent events referring to subdirs with dirent events
referring to non subdirs, otherwise, user won't be able to tell from a
mask FAN_CREATE|FAN_DELETE|FAN_ONDIR if it describes mkdir+unlink pair
or rmdir+create pair of events.
For backward compatibility and consistency, do not report FAN_ONDIR
to user in legacy fanotify mode (reporting fd) and report FAN_ONDIR
to user in FAN_REPORT_FID mode for all event types.
Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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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>
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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>
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A new event mask FAN_OPEN_EXEC_PERM has been defined. This allows users
to receive events and grant access to files that are intending to be
opened for execution. Events of FAN_OPEN_EXEC_PERM type will be
generated when a file has been opened by using either execve(),
execveat() or uselib() system calls.
This acts in the same manner as previous permission event mask, meaning
that an access response is required from the user application in order
to permit any further operations on the file.
Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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A new event mask FAN_OPEN_EXEC has been defined so that users have the
ability to receive events specifically when a file has been opened with
the intent to be executed. Events of FAN_OPEN_EXEC type will be
generated when a file has been opened using either execve(), execveat()
or uselib() system calls.
The feature is implemented within fsnotify_open() by generating the
FAN_OPEN_EXEC event type if __FMODE_EXEC is set within file->f_flags.
Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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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>
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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>
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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>
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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>
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The new mark flag FAN_MARK_FILESYSTEMS collides with existing internal
flag FAN_MARK_ONDIR. Change internal flag value to avoid the collision.
Fixes: d54f4fba889b ("fanotify: add API to attach/detach super block mark")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
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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>
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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>
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Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
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To implement per event type optional headers we are interested in
knowing how long the metadata structure is. This patch slits the __u32
version field into a __u8 version and a __u16 metadata_len field (with
__u8 left over). This should allow for backwards compat ABI.
Signed-off-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
[rewrote descrtion and changed object sizes and ordering - eparis]
Signed-off-by: Eric Paris <eparis@redhat.com>
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FAN_NOFD is used in fanotify events that do not provide an open file
descriptor (like the overflow_event).
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
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Since fanotify has decided to be careful about alignment and packing
rather than rely on __attribute__((packed)) for multiarch support.
Since this attribute isn't doing anything on fanotify_response we just
drop it. This does not break API/ABI.
Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@sophos.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
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The comments for FAN_CLOSE_WRITE and FAN_CLOSE_NOWRITE do not match
FS_CLOSE_WRITE and FS_CLOSE_NOWRITE, respectively. WRITE is for
writable files while NOWRITE is for non-writable files.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
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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>
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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>
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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>
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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>
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fanotify is supposed to be able to flush all marks. This is mostly useful
for the AV community to flush all cached decisions on a security policy
change. This functionality has existed in the kernel but wasn't correctly
exposed to userspace.
Signed-off-by: Eric Paris <eparis@redhat.com>
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Currently the userspace struct exposed by fanotify uses
__attribute__((packed)) to make sure that alignment works on multiarch
platforms. Since this causes a severe performance penalty on some
platforms we are going to switch to using explicit alignment notation on
the 64bit values so we don't have to use 'packed'
Signed-off-by: Eric Paris <eparis@redhat.com>
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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>
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resize pid and reorder the fanotify_event_metadata so it is naturally
aligned and we can work towards dropping the packed attributed
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@sophos.com>
Cc: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Eric Paris <eparis@redhat.com>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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