6.1-stable review patch. If anyone has any objections, please let me know.
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From: Amir Goldstein amir73il@gmail.com
commit ab048302026d7701e7fbd718917e0dbcff0c4223 upstream.
Some local filesystems support setting persistent fileattr flags (e.g. FS_NOATIME_FL) on directories and regular files via ioctl. Some of those persistent fileattr flags are reflected to vfs as in-memory inode flags (e.g. S_NOATIME).
Overlayfs uses the in-memory inode flags (e.g. S_NOATIME) on a lower file as an indication that a the lower file may have persistent inode fileattr flags (e.g. FS_NOATIME_FL) that need to be copied to upper file.
However, in some cases, the S_NOATIME in-memory flag could be a false indication for persistent FS_NOATIME_FL fileattr. For example, with NFS and FUSE lower fs, as was the case in the two bug reports, the S_NOATIME flag is set unconditionally for all inodes.
Users cannot set persistent fileattr flags on symlinks and special files, but in some local fs, such as ext4/btrfs/tmpfs, the FS_NOATIME_FL fileattr flag are inheritted to symlinks and special files from parent directory.
In both cases described above, when lower symlink has the S_NOATIME flag, overlayfs will try to copy the symlink's fileattrs and fail with error ENOXIO, because it could not open the symlink for the ioctl security hook.
To solve this failure, do not attempt to copyup fileattrs for anything other than directories and regular files.
Reported-by: Ruiwen Zhao ruiwen@google.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217850 Fixes: 72db82115d2b ("ovl: copy up sync/noatime fileattr flags") Cc: stable@vger.kernel.org # v5.15 Reviewed-by: Miklos Szeredi miklos@szeredi.hu Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/overlayfs/copy_up.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -580,7 +580,8 @@ static int ovl_copy_up_metadata(struct o if (err) return err;
- if (inode->i_flags & OVL_COPY_I_FLAGS_MASK) { + if (inode->i_flags & OVL_COPY_I_FLAGS_MASK && + (S_ISREG(c->stat.mode) || S_ISDIR(c->stat.mode))) { /* * Copy the fileattr inode flags that are the source of already * copied i_flags