* Add remaining pieces of Kerberos support (closes: #275472):

  - Add GSSAPI key exchange support from
    http://www.sxw.org.uk/computing/patches/openssh.html (thanks, Stephen
    Frost).

1 files changed, 39 insertions, 0 deletions

diff --git a/auth2-gss.c b/auth2-gss.c
index 4d468a0e8..9295d531b 100644
--- a/auth2-gss.c
+++ b/auth2-gss.c
@@ -47,6 +47,39 @@ 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
@@ -285,6 +318,12 @@ input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
         userauth_finish(authctxt, authenticated, "gssapi-with-mic");
 }
 
+Authmethod method_gsskeyex = {
+        "gssapi-keyx",
+        userauth_gsskeyex,
+        &options.gss_authentication
+};
+
 Authmethod method_gssapi = {
         "gssapi-with-mic",
         userauth_gssapi,