fanotify: Report fid info for file related file system errors
Plumb the pieces to add a FID report to error records. Since all error
event memory must be pre-allocated, we pre-allocate the maximum file
handle size possible, such that it should always fit.
For errors that don't expose a file handle, report it with an invalid
FID. Internally we use zero-length FILEID_ROOT file handle for passing
the information (which we report as zero-length FILEID_INVALID file
handle to userspace) so we update the handle reporting code to deal with
this case correctly.
Link: https://lore.kernel.org/r/20211025192746.66445-27-krisman@collabora.com
Link: https://lore.kernel.org/r/20211025192746.66445-25-krisman@collabora.com
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
[Folded two patches into 2 to make series bisectable]
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index a9b5c36..ff4a737 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;