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authorAmir Goldstein <amir73il@gmail.com>2022-06-27 20:47:19 +0300
committerJan Kara <jack@suse.cz>2022-06-28 11:18:13 +0200
commit8698e3bab4dd7968666e84e111d0bfd17c040e77 (patch)
tree984d2443835b1349a34b90bed5a45c970b5775b1 /fs/notify
parentca1fdab7fd27eb069df1384b2850dcd0c2bebe8d (diff)
downloadlwn-8698e3bab4dd7968666e84e111d0bfd17c040e77.tar.gz
lwn-8698e3bab4dd7968666e84e111d0bfd17c040e77.zip
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>
Diffstat (limited to 'fs/notify')
-rw-r--r--fs/notify/fanotify/fanotify_user.c34
1 files changed, 19 insertions, 15 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index c2255b440df9..b08ce0d821a7 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1513,8 +1513,15 @@ static int fanotify_test_fid(struct dentry *dentry)
return 0;
}
-static int fanotify_events_supported(struct path *path, __u64 mask)
+static int fanotify_events_supported(struct fsnotify_group *group,
+ struct path *path, __u64 mask,
+ unsigned int flags)
{
+ unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
+ /* Strict validation of events in non-dir inode mask with v5.17+ APIs */
+ bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) ||
+ (mask & FAN_RENAME);
+
/*
* Some filesystems such as 'proc' acquire unusual locks when opening
* files. For them fanotify permission events have high chances of
@@ -1526,6 +1533,16 @@ static int fanotify_events_supported(struct path *path, __u64 mask)
if (mask & FANOTIFY_PERM_EVENTS &&
path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM)
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.
+ */
+ if (strict_dir_events && mark_type == FAN_MARK_INODE &&
+ !d_is_dir(path->dentry) && (mask & FANOTIFY_DIRONLY_EVENT_BITS))
+ return -ENOTDIR;
+
return 0;
}
@@ -1672,7 +1689,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
goto fput_and_out;
if (flags & FAN_MARK_ADD) {
- ret = fanotify_events_supported(&path, mask);
+ ret = fanotify_events_supported(group, &path, mask, flags);
if (ret)
goto path_put_and_out;
}
@@ -1695,19 +1712,6 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
else
mnt = path.mnt;
- /*
- * FAN_RENAME is not allowed on non-dir (for now).
- * We shouldn't have allowed setting any dirent events in mask of
- * non-dir, but because we always allowed it, error only if group
- * was initialized with the new flag FAN_REPORT_TARGET_FID.
- */
- ret = -ENOTDIR;
- if (inode && !S_ISDIR(inode->i_mode) &&
- ((mask & FAN_RENAME) ||
- ((mask & FANOTIFY_DIRENT_EVENTS) &&
- FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID))))
- goto path_put_and_out;
-
/* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */
if (mnt || !S_ISDIR(inode->i_mode)) {
mask &= ~FAN_EVENT_ON_CHILD;