nfsd: fix access checking for NLM under XPRTSEC policies

commit 0813c5f upstream.

When an export policy with xprtsec policy is set with "tls"
and/or "mtls", but an NFS client is doing a v3 xprtsec=tls
mount, then NLM locking calls fail with an error because
there is currently no support for NLM with TLS.

Until such support is added, allow NLM calls under TLS-secured
policy.

Fixes: 4cc9b9f ("nfsd: refine and rename NFSD_MAY_LOCK")
Cc: [email protected]
Signed-off-by: Olga Kornievskaia <[email protected]>
Reviewed-by: NeilBrown <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Olga Kornievskaia

fs/nfsd/export.c

@@ -1115,7 +1115,8 @@ __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp,
 		    test_bit(XPT_PEER_AUTH, &xprt->xpt_flags))
 			goto ok;
 	}
-	goto denied;
+	if (!may_bypass_gss)
+		goto denied;
 
 ok:
 	/* legacy gss-only clients are always OK: */