On Mon 27-06-22 20:47:19, Amir Goldstein wrote:
> 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@xxxxxxxxxx/
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Thanks! I've taken the patch to my tree.
Honza
> [1] https://github.com/amir73il/ltp/commits/fan_enotdir
> [2] https://github.com/amir73il/man-pages/commits/fanotify_target_fid
>
>
> fs/notify/fanotify/fanotify_user.c | 34 +++++++++++++++++-------------
> include/linux/fanotify.h | 4 ++++
> 2 files changed, 23 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;
> diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
> index edc28555814c..e517dbcf74ed 100644
> --- a/include/linux/fanotify.h
> +++ b/include/linux/fanotify.h
> @@ -111,6 +111,10 @@
> FANOTIFY_PERM_EVENTS | \
> FAN_Q_OVERFLOW | FAN_ONDIR)
>
> +/* Events and flags relevant only for directories */
> +#define FANOTIFY_DIRONLY_EVENT_BITS (FANOTIFY_DIRENT_EVENTS | \
> + FAN_EVENT_ON_CHILD | FAN_ONDIR)
> +
> #define ALL_FANOTIFY_EVENT_BITS (FANOTIFY_OUTGOING_EVENTS | \
> FANOTIFY_EVENT_FLAGS)
>
> --
> 2.25.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
