NFSD: Do not allow NFSv4 (N)VERIFY to check POSIX ACL attributes

Section 9.3 of draft-ietf-nfsv4-posix-acls-00 prohibits use of
the POSIX ACL attributes with VERIFY and NVERIFY operations: the
server MUST reply NFS4ERR_INVAL when a client attempts this.

Beyond the protocol requirement, comparison of POSIX draft ACLs
via (N)VERIFY presents an implementation challenge. Clients are
not required to order the ACEs within a POSIX ACL in any
particular way, making reliable attribute comparison impractical.

Return nfserr_inval when the client requests FATTR4_POSIX_ACCESS_ACL
or FATTR4_POSIX_DEFAULT_ACL in a VERIFY or NVERIFY operation.

Signed-off-by: Rick Macklem <rmacklem@uoguelph.ca>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: rmacklem

fs/nfsd/nfs4proc.c

@@ -2380,6 +2380,11 @@ _nfsd4_verify(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	if (verify->ve_attrlen & 3)
 		return nfserr_inval;
 
+	/* The POSIX draft ACLs cannot be tested via (N)VERIFY. */
+	if (verify->ve_bmval[2] & (FATTR4_WORD2_POSIX_DEFAULT_ACL |
+					FATTR4_WORD2_POSIX_ACCESS_ACL))
+		return nfserr_inval;
+
 	/* count in words:
 	 *   bitmap_len(1) + bitmap(2) + attr_len(1) = 4
 	 */