userns: Teach security_path_chown to take kuids and kgids

Don't make the security modules deal with raw user space uid and
gids instead pass in a kuid_t and a kgid_t so that security modules
only have to deal with internal kernel uids and gids.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: James Morris <james.l.morris@oracle.com>
Cc: John Johansen <john.johansen@canonical.com>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

security/tomoyo/tomoyo.c

@@ -373,13 +373,15 @@ static int tomoyo_path_chmod(struct path *path, umode_t mode)
  *
  * Returns 0 on success, negative value otherwise.
  */
-static int tomoyo_path_chown(struct path *path, uid_t uid, gid_t gid)
+static int tomoyo_path_chown(struct path *path, kuid_t uid, kgid_t gid)
 {
 	int error = 0;
-	if (uid != (uid_t) -1)
-		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path, uid);
-	if (!error && gid != (gid_t) -1)
-		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path, gid);
+	if (uid_valid(uid))
+		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
+						from_kuid(&init_user_ns, uid));
+	if (!error && gid_valid(gid))
+		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
+						from_kgid(&init_user_ns, gid));
 	return error;
 }