NFS: Check the TLS certificate fields in nfs_match_client()

If the TLS security policy is of type RPC_XPRTSEC_TLS_X509, then the
cert_serial and privkey_serial fields need to match as well since they
define the client's identity, as presented to the server.

Fixes: 90c9550 ("NFS: support the kernel keyring for TLS")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

Author: Trond Myklebust

fs/nfs/client.c

@@ -338,6 +338,14 @@ static struct nfs_client *nfs_match_client(const struct nfs_client_initdata *dat
 		/* Match the xprt security policy */
 		if (clp->cl_xprtsec.policy != data->xprtsec.policy)
 			continue;
+		if (clp->cl_xprtsec.policy == RPC_XPRTSEC_TLS_X509) {
+			if (clp->cl_xprtsec.cert_serial !=
+			    data->xprtsec.cert_serial)
+				continue;
+			if (clp->cl_xprtsec.privkey_serial !=
+			    data->xprtsec.privkey_serial)
+				continue;
+		}
 
 		refcount_inc(&clp->cl_count);
 		return clp;