diff mbox series

[v9,24/31] fanotify: Report fid entry even for zero-length file_handle

Message ID 20211025192746.66445-25-krisman@collabora.com (mailing list archive)
State New, archived
Headers show
Series file system-wide error monitoring | expand

Commit Message

Gabriel Krisman Bertazi Oct. 25, 2021, 7:27 p.m. UTC 
Non-inode errors will reported with an empty file_handle.  In
preparation for that, allow some events to print the FID record even if
there isn't any file_handle encoded

Even though FILEID_ROOT is used internally, make zero-length file
handles be reported as FILEID_INVALID.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v8:
  - Move fanotify_event_has_object_fh check here (jan)
---
 fs/notify/fanotify/fanotify.h      | 3 +++
 fs/notify/fanotify/fanotify_user.c | 8 +++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

Comments

Amir Goldstein Oct. 26, 2021, 9:09 a.m. UTC | #1 
On Mon, Oct 25, 2021 at 10:30 PM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> Non-inode errors will reported with an empty file_handle.  In
> preparation for that, allow some events to print the FID record even if
> there isn't any file_handle encoded
>
> Even though FILEID_ROOT is used internally, make zero-length file
> handles be reported as FILEID_INVALID.
>
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
>
> ---
> Changes since v8:
>   - Move fanotify_event_has_object_fh check here (jan)

Logically, this move is wrong, because after this patch,
copy_fid_info_to_user() can theoretically be called with NULL fh in the
existing construct of:
  if (fanotify_event_has_object_fh(event)) {
  ...
    ret = copy_fid_info_to_user(fanotify_event_fsid(event),

fanotify_event_object_fh(event),

The thing that prevents this case in effect is that FAN_FS_ERROR
is not yet wired, but I am not sure if leaving this theoretic bisect
issue is a good idea.

Anyway, that's a very minor theoretic issue and I am sure Jan can
decide whether to deal with it and how (no need to post v10 IMO).

Thanks,
Amir.
Jan Kara Oct. 26, 2021, 12:06 p.m. UTC | #2 
On Tue 26-10-21 12:09:19, Amir Goldstein wrote:
> On Mon, Oct 25, 2021 at 10:30 PM Gabriel Krisman Bertazi
> <krisman@collabora.com> wrote:
> >
> > Non-inode errors will reported with an empty file_handle.  In
> > preparation for that, allow some events to print the FID record even if
> > there isn't any file_handle encoded
> >
> > Even though FILEID_ROOT is used internally, make zero-length file
> > handles be reported as FILEID_INVALID.
> >
> > Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> > Reviewed-by: Jan Kara <jack@suse.cz>
> > Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> >
> > ---
> > Changes since v8:
> >   - Move fanotify_event_has_object_fh check here (jan)
> 
> Logically, this move is wrong, because after this patch,
> copy_fid_info_to_user() can theoretically be called with NULL fh in the
> existing construct of:
>   if (fanotify_event_has_object_fh(event)) {
>   ...
>     ret = copy_fid_info_to_user(fanotify_event_fsid(event),
> 
> fanotify_event_object_fh(event),
> 
> The thing that prevents this case in effect is that FAN_FS_ERROR
> is not yet wired, but I am not sure if leaving this theoretic bisect
> issue is a good idea.
> 
> Anyway, that's a very minor theoretic issue and I am sure Jan can
> decide whether to deal with it and how (no need to post v10 IMO).

Hum, correct. I guess I'll just fold this patch into patch 26. Logically
they are very close anyway.

								Honza
diff mbox series

Patch

diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 80af269eebb8..f51ab6e556e8 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -266,6 +266,9 @@  static inline int fanotify_event_dir_fh_len(struct fanotify_event *event)
 
 static inline bool fanotify_event_has_object_fh(struct fanotify_event *event)
 {
+	/* For error events, even zeroed fh are reported. */
+	if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
+		return true;
 	return fanotify_event_object_fh_len(event) > 0;
 }
 
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index a9b5c36ee49e..ff4a7373f7a5 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -339,9 +339,6 @@  static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
 	pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n",
 		 __func__, fh_len, name_len, info_len, count);
 
-	if (!fh_len)
-		return 0;
-
 	if (WARN_ON_ONCE(len < sizeof(info) || len > count))
 		return -EFAULT;
 
@@ -376,6 +373,11 @@  static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
 
 	handle.handle_type = fh->type;
 	handle.handle_bytes = fh_len;
+
+	/* Mangle handle_type for bad file_handle */
+	if (!fh_len)
+		handle.handle_type = FILEID_INVALID;
+
 	if (copy_to_user(buf, &handle, sizeof(handle)))
 		return -EFAULT;