userns: Convert stat to return values mapped from kuids and kgids

- Store uids and gids with kuid_t and kgid_t in struct kstat
- Convert uid and gids to userspace usable values with
  from_kuid and from_kgid

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

arch/parisc/hpux/fs.c

@@ -159,8 +159,8 @@ static int cp_hpux_stat(struct kstat *stat, struct hpux_stat64 __user *statbuf)
 	tmp.st_ino = stat->ino;
 	tmp.st_mode = stat->mode;
 	tmp.st_nlink = stat->nlink;
-	tmp.st_uid = stat->uid;
-	tmp.st_gid = stat->gid;
+	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
+	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
 	tmp.st_rdev = new_encode_dev(stat->rdev);
 	tmp.st_size = stat->size;
 	tmp.st_atime = stat->atime.tv_sec;