1 files changed, 41 insertions, 0 deletions

diff --git a/auth2-gss.c b/auth2-gss.c
index 95844a05e..539654ee0 100644
--- a/auth2-gss.c
+++ b/auth2-gss.c
@@ -46,6 +46,39 @@ static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
 static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
 static void input_gssapi_errtok(int, u_int32_t, void *);
 
+/* 
+ * The 'gssapi_keyex' userauth mechanism.
+ */
+static int
+userauth_gsskeyex(Authctxt *authctxt)
+{
+        int authenticated = 0;
+        Buffer b;
+        gss_buffer_desc mic, gssbuf;
+        u_int len;
+
+        mic.value = packet_get_string(&len);
+        mic.length = len;
+
+        packet_check_eom();
+
+        ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
+            "gssapi-keyex");
+
+        gssbuf.value = buffer_ptr(&b);
+        gssbuf.length = buffer_len(&b);
+
+        /* gss_kex_context is NULL with privsep, so we can't check it here */
+        if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context, 
+            &gssbuf, &mic))))
+                authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
+        
+        buffer_free(&b);
+        xfree(mic.value);
+
+        return (authenticated);
+}
+
 /*
  * We only support those mechanisms that we know about (ie ones that we know
  * how to check local user kuserok and the like)
@@ -96,11 +129,13 @@ userauth_gssapi(Authctxt *authctxt)
 
         if (!present) {
                 xfree(doid);
+                authctxt->server_caused_failure = 1;
                 return (0);
         }
 
         if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
                 xfree(doid);
+                authctxt->server_caused_failure = 1;
                 return (0);
         }
 
@@ -284,6 +319,12 @@ input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
         userauth_finish(authctxt, authenticated, "gssapi-with-mic");
 }
 
+Authmethod method_gsskeyex = {
+        "gssapi-keyex",
+        userauth_gsskeyex,
+        &options.gss_authentication
+};
+
 Authmethod method_gssapi = {
         "gssapi-with-mic",
         userauth_gssapi,