kernel/linux.git/fs/notify, branch v5.10.258

fanotify: fix false positive on permission events

2026-06-01T15:29:23+00:00

commit 7746e3bd4cc19b5092e00d32d676e329bfcb6900 upstream. fsnotify_get_mark_safe() may return false for a mark on an unrelated group, which results in bypassing the permission check. Fix by skipping over detached marks that are not in the current group. CC: stable@vger.kernel.org Fixes: abc77577a669 ("fsnotify: Provide framework for dropping SRCU lock in ->handle_event") Signed-off-by: Miklos Szeredi Link: https://patch.msgid.link/20260410144950.156160-1-mszeredi@redhat.com Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails

2026-06-01T15:29:20+00:00

commit 6a320935fa4293e9e599ec9f85dc9eb3be7029f8 upstream. When fsnotify_add_inode_mark_locked() fails in inotify_new_watch(), the error path calls inotify_remove_from_idr() but does not call dec_inotify_watches() to undo the preceding inc_inotify_watches(). This leaks a watch count, and repeated failures can exhaust the max_user_watches limit with -ENOSPC even when no watches are active. Prior to commit 1cce1eea0aff ("inotify: Convert to using per-namespace limits"), the watch count was incremented after fsnotify_add_mark_locked() succeeded, so this path was not affected. The conversion moved inc_inotify_watches() before the mark insertion without adding the corresponding rollback. Add the missing dec_inotify_watches() call in the error path. Fixes: 1cce1eea0aff ("inotify: Convert to using per-namespace limits") Cc: stable@vger.kernel.org Signed-off-by: Chia-Ming Chang Signed-off-by: robbieko Reviewed-by: Nikolay Borisov Link: https://patch.msgid.link/20260224093442.3076294-1-chiamingc@synology.com Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

fsnotify: do not generate ACCESS/MODIFY events on child for special files

2026-01-19T12:11:51+00:00

commit 635bc4def026a24e071436f4f356ea08c0eed6ff upstream. inotify/fanotify do not allow users with no read access to a file to subscribe to events (e.g. IN_ACCESS/IN_MODIFY), but they do allow the same user to subscribe for watching events on children when the user has access to the parent directory (e.g. /dev). Users with no read access to a file but with read access to its parent directory can still stat the file and see if it was accessed/modified via atime/mtime change. The same is not true for special files (e.g. /dev/null). Users will not generally observe atime/mtime changes when other users read/write to special files, only when someone sets atime/mtime via utimensat(). Align fsnotify events with this stat behavior and do not generate ACCESS/MODIFY events to parent watchers on read/write of special files. The events are still generated to parent watchers on utimensat(). This closes some side-channels that could be possibly used for information exfiltration [1]. [1] https://snee.la/pdf/pubs/file-notification-attacks.pdf Reported-by: Sudheendra Raghav Neela CC: stable@vger.kernel.org Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

fsnotify: fix sending inotify event with unexpected filename

2024-12-14T18:48:08+00:00

commit aa52c54da40d9eee3ba87c05cdcb0cd07c04fa13 upstream. We got a report that adding a fanotify filsystem watch prevents tail -f from receiving events. Reproducer: 1. Create 3 windows / login sessions. Become root in each session. 2. Choose a mounted filesystem that is pretty quiet; I picked /boot. 3. In the first window, run: fsnotifywait -S -m /boot 4. In the second window, run: echo data >> /boot/foo 5. In the third window, run: tail -f /boot/foo 6. Go back to the second window and run: echo more data >> /boot/foo 7. Observe that the tail command doesn't show the new data. 8. In the first window, hit control-C to interrupt fsnotifywait. 9. In the second window, run: echo still more data >> /boot/foo 10. Observe that the tail command in the third window has now printed the missing data. When stracing tail, we observed that when fanotify filesystem mark is set, tail does get the inotify event, but the event is receieved with the filename: read(4, "\1\0\0\0\2\0\0\0\0\0\0\0\20\0\0\0foo\0\0\0\0\0\0\0\0\0\0\0\0\0", 50) = 32 This is unexpected, because tail is watching the file itself and not its parent and is inconsistent with the inotify event received by tail when fanotify filesystem mark is not set: read(4, "\1\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0", 50) = 16 The inteference between different fsnotify groups was caused by the fact that the mark on the sb requires the filename, so the filename is passed to fsnotify(). Later on, fsnotify_handle_event() tries to take care of not passing the filename to groups (such as inotify) that are interested in the filename only when the parent is watching. But the logic was incorrect for the case that no group is watching the parent, some groups are watching the sb and some watching the inode. Reported-by: Miklos Szeredi Fixes: 7372e79c9eb9 ("fanotify: fix logic of reporting name info with watched parent") Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

fsnotify: clear PARENT_WATCHED flags lazily

2024-09-12T09:06:41+00:00

[ Upstream commit 172e422ffea20a89bfdc672741c1aad6fbb5044e ] In some setups directories can have many (usually negative) dentries. Hence __fsnotify_update_child_dentry_flags() function can take a significant amount of time. Since the bulk of this function happens under inode->i_lock this causes a significant contention on the lock when we remove the watch from the directory as the __fsnotify_update_child_dentry_flags() call from fsnotify_recalc_mask() races with __fsnotify_update_child_dentry_flags() calls from __fsnotify_parent() happening on children. This can lead upto softlockup reports reported by users. Fix the problem by calling fsnotify_update_children_dentry_flags() to set PARENT_WATCHED flags only when parent starts watching children. When parent stops watching children, clear false positive PARENT_WATCHED flags lazily in __fsnotify_parent() for each accessed child. Suggested-by: Jan Kara Signed-off-by: Amir Goldstein Signed-off-by: Stephen Brennan Signed-off-by: Jan Kara Signed-off-by: Sasha Levin

fanotify: Remove obsoleted fanotify_event_has_path()

2024-06-21T12:54:03+00:00

[ Upstream commit 7a80bf902d2bc722b4477442ee772e8574603185 ] All uses of fanotify_event_has_path() have been removed since commit 9c61f3b560f5 ("fanotify: break up fanotify_alloc_event()"), now it is useless, so remove it. Link: https://lore.kernel.org/r/20220926023018.1505270-1-cuigaosheng1@huawei.com Signed-off-by: Gaosheng Cui Signed-off-by: Jan Kara [ cel: resolved merge conflict ] Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin

fsnotify: remove unused declaration

2024-06-21T12:54:03+00:00

[ Upstream commit f847c74d6e89f10926db58649a05b99237258691 ] fsnotify_alloc_event_holder() and fsnotify_destroy_event_holder() has been removed since commit 7053aee26a35 ("fsnotify: do not share events between notification groups"), so remove it. Reviewed-by: Ritesh Harjani (IBM) Signed-off-by: Gaosheng Cui Signed-off-by: Jan Kara Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin

fs/notify: constify path

2024-06-21T12:54:02+00:00

[ Upstream commit d5bf88895f24686641c39420ee6df716dc1d95d8 ] Reviewed-by: Matthew Bobrowski Reviewed-by: Christian Brauner (Microsoft) Signed-off-by: Al Viro Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin

fsnotify: Fix comment typo

2024-06-21T12:53:46+00:00

[ Upstream commit feee1ce45a5666bbdb08c5bb2f5f394047b1915b ] The double `if' is duplicated in line 104, remove one. Signed-off-by: Xin Gao Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20220722194639.18545-1-gaoxin@cdjrlc.com Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin

fanotify: introduce FAN_MARK_IGNORE

2024-06-21T12:53:46+00:00

[ Upstream commit e252f2ed1c8c6c3884ab5dd34e003ed21f1fe6e0 ] 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 Signed-off-by: Jan Kara Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin