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authorAmir Goldstein <amir73il@gmail.com>2023-06-29 07:20:44 +0300
committerJan Kara <jack@suse.cz>2023-07-04 13:29:29 +0200
commit69562eb0bd3e6bb8e522a7b254334e0fb30dff0c (patch)
tree8b322cf155785737c7aa57f6337e6608760a2a62 /fs
parenta901a3568fd26ca9c4a82d8bc5ed5b3ed844d451 (diff)
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/notify/fanotify/fanotify_user.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 95d7d8790bc3..f69c451018e3 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1623,6 +1623,20 @@ static int fanotify_events_supported(struct fsnotify_group *group,
return -EINVAL;
/*
+ * mount and sb marks are not allowed on kernel internal pseudo fs,
+ * like pipe_mnt, because that would subscribe to events on all the
+ * anonynous pipes in the system.
+ *
+ * SB_NOUSER covers all of the internal pseudo fs whose objects are not
+ * exposed to user's mount namespace, but there are other SB_KERNMOUNT
+ * fs, like nsfs, debugfs, for which the value of allowing sb and mount
+ * mark is questionable. For now we leave them alone.
+ */
+ if (mark_type != FAN_MARK_INODE &&
+ path->mnt->mnt_sb->s_flags & SB_NOUSER)
+ return -EINVAL;
+
+ /*
* We shouldn't have allowed setting dirent events and the directory
* flags FAN_ONDIR and FAN_EVENT_ON_CHILD in mask of non-dir inode,
* but because we always allowed it, error only when using new APIs.