queue-5.15/fanotify-split-fsid-check-from-other-fid-mode-checks.patch

   1 From 31d4d90185c99b8856cba30e84c926750b343221 Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Mon, 25 Oct 2021 16:27:21 -0300
   4 Subject: fanotify: Split fsid check from other fid mode checks
   5
   6 From: Gabriel Krisman Bertazi <krisman@collabora.com>
   7
   8 [ Upstream commit 8299212cbdb01a5867e230e961f82e5c02a6de34 ]
   9
  10 FAN_FS_ERROR will require fsid, but not necessarily require the
  11 filesystem to expose a file handle.  Split those checks into different
  12 functions, so they can be used separately when setting up an event.
  13
  14 While there, update a comment about tmpfs having 0 fsid, which is no
  15 longer true.
  16
  17 Link: https://lore.kernel.org/r/20211025192746.66445-7-krisman@collabora.com
  18 Reviewed-by: Amir Goldstein <amir73il@gmail.com>
  19 Reviewed-by: Jan Kara <jack@suse.cz>
  20 Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
  21 Signed-off-by: Jan Kara <jack@suse.cz>
  22 Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
  23 ---
  24  fs/notify/fanotify/fanotify_user.c | 27 ++++++++++++++++++---------
  25  1 file changed, 18 insertions(+), 9 deletions(-)
  26
  27 diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
  28 index 20b743b05b997..8cf8e63a2c3e8 100644
  29 --- a/fs/notify/fanotify/fanotify_user.c
  30 +++ b/fs/notify/fanotify/fanotify_user.c
  31 @@ -1300,16 +1300,15 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
  32         return fd;
  33  }
  34
  35 -/* Check if filesystem can encode a unique fid */
  36 -static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
  37 +static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
  38  {
  39         __kernel_fsid_t root_fsid;
  40         int err;
  41
  42         /*
  43 -        * Make sure path is not in filesystem with zero fsid (e.g. tmpfs).
  44 +        * Make sure dentry is not of a filesystem with zero fsid (e.g. fuse).
  45          */
  46 -       err = vfs_get_fsid(path->dentry, fsid);
  47 +       err = vfs_get_fsid(dentry, fsid);
  48         if (err)
  49                 return err;
  50
  51 @@ -1317,10 +1316,10 @@ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
  52                 return -ENODEV;
  53
  54         /*
  55 -        * Make sure path is not inside a filesystem subvolume (e.g. btrfs)
  56 +        * Make sure dentry is not of a filesystem subvolume (e.g. btrfs)
  57          * which uses a different fsid than sb root.
  58          */
  59 -       err = vfs_get_fsid(path->dentry->d_sb->s_root, &root_fsid);
  60 +       err = vfs_get_fsid(dentry->d_sb->s_root, &root_fsid);
  61         if (err)
  62                 return err;
  63
  64 @@ -1328,6 +1327,12 @@ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
  65             root_fsid.val[1] != fsid->val[1])
  66                 return -EXDEV;
  67
  68 +       return 0;
  69 +}
  70 +
  71 +/* Check if filesystem can encode a unique fid */
  72 +static int fanotify_test_fid(struct dentry *dentry)
  73 +{
  74         /*
  75          * We need to make sure that the file system supports at least
  76          * encoding a file handle so user can use name_to_handle_at() to
  77 @@ -1335,8 +1340,8 @@ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
  78          * objects. However, name_to_handle_at() requires that the
  79          * filesystem also supports decoding file handles.
  80          */
  81 -       if (!path->dentry->d_sb->s_export_op ||
  82 -           !path->dentry->d_sb->s_export_op->fh_to_dentry)
  83 +       if (!dentry->d_sb->s_export_op ||
  84 +           !dentry->d_sb->s_export_op->fh_to_dentry)
  85                 return -EOPNOTSUPP;
  86
  87         return 0;
  88 @@ -1505,7 +1510,11 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
  89         }
  90
  91         if (fid_mode) {
  92 -               ret = fanotify_test_fid(&path, &__fsid);
  93 +               ret = fanotify_test_fsid(path.dentry, &__fsid);
  94 +               if (ret)
  95 +                       goto path_put_and_out;
  96 +
  97 +               ret = fanotify_test_fid(path.dentry);
  98                 if (ret)
  99                         goto path_put_and_out;
 100
 101 --
 102 2.43.0
 103