+static int check_gss_callback_principal(struct nfs_client *clp,
+ struct svc_rqst *rqstp)
+{
+ struct rpc_clnt *r = clp->cl_rpcclient;
+ char *p = svc_gss_principal(rqstp);
+
+ /*
+ * It might just be a normal user principal, in which case
+ * userspace won't bother to tell us the name at all.
+ */
+ if (p == NULL)
+ return SVC_DENIED;
+
+ /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
+
+ if (memcmp(p, "nfs@", 4) != 0)
+ return SVC_DENIED;
+ p += 4;
+ if (strcmp(p, r->cl_server) != 0)
+ return SVC_DENIED;
+ return SVC_OK;
+}
+