1 files changed, 131 insertions, 2 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
index 10e4f0a08..c6a1b1271 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -162,6 +162,11 @@ ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
         struct kex *kex;
         int r;
 
+#ifdef GSSAPI
+        char *orig = NULL, *gss = NULL;
+        char *gss_host = NULL;
+#endif
+
         xxx_host = host;
         xxx_hostaddr = hostaddr;
 
@@ -194,6 +199,35 @@ ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
                     order_hostkeyalgs(host, hostaddr, port));
         }
 
+#ifdef GSSAPI
+        if (options.gss_keyex) {
+                /* Add the GSSAPI mechanisms currently supported on this
+                 * client to the key exchange algorithm proposal */
+                orig = myproposal[PROPOSAL_KEX_ALGS];
+
+                if (options.gss_server_identity)
+                        gss_host = xstrdup(options.gss_server_identity);
+                else if (options.gss_trust_dns)
+                        gss_host = remote_hostname(active_state);
+                else
+                        gss_host = xstrdup(host);
+
+                gss = ssh_gssapi_client_mechanisms(gss_host,
+                    options.gss_client_identity);
+                if (gss) {
+                        debug("Offering GSSAPI proposal: %s", gss);
+                        xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
+                            "%s,%s", gss, orig);
+
+                        /* If we've got GSSAPI algorithms, then we also
+                         * support the 'null' hostkey, as a last resort */
+                        orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
+                        xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
+                            "%s,null", orig);
+                }
+        }
+#endif
+
         if (options.rekey_limit || options.rekey_interval)
                 packet_set_rekey_limits(options.rekey_limit,
                     options.rekey_interval);
@@ -215,15 +249,41 @@ ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 # endif
 #endif
         kex->kex[KEX_C25519_SHA256] = kexc25519_client;
+#ifdef GSSAPI
+        if (options.gss_keyex) {
+                kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
+                kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
+                kex->kex[KEX_GSS_GEX_SHA1] = kexgss_client;
+        }
+#endif
         kex->client_version_string=client_version_string;
         kex->server_version_string=server_version_string;
         kex->verify_host_key=&verify_host_key_callback;
 
+#ifdef GSSAPI
+        if (options.gss_keyex) {
+                kex->gss_deleg_creds = options.gss_deleg_creds;
+                kex->gss_trust_dns = options.gss_trust_dns;
+                kex->gss_client = options.gss_client_identity;
+                kex->gss_host = gss_host;
+        }
+#endif
+
         ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
 
         /* remove ext-info from the KEX proposals for rekeying */
         myproposal[PROPOSAL_KEX_ALGS] =
             compat_kex_proposal(options.kex_algorithms);
+#ifdef GSSAPI
+        /* repair myproposal after it was crumpled by the */
+        /* ext-info removal above */
+        if (gss) {
+                orig = myproposal[PROPOSAL_KEX_ALGS];
+                xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
+                    "%s,%s", gss, orig);
+                free(gss);
+        }
+#endif
         if ((r = kex_prop2buf(kex->my, myproposal)) != 0)
                 fatal("kex_prop2buf: %s", ssh_err(r));
 
@@ -314,6 +374,7 @@ int	input_gssapi_token(int type, u_int32_t, struct ssh *);
 int     input_gssapi_hash(int type, u_int32_t, struct ssh *);
 int     input_gssapi_error(int, u_int32_t, struct ssh *);
 int     input_gssapi_errtok(int, u_int32_t, struct ssh *);
+int     userauth_gsskeyex(Authctxt *authctxt);
 #endif
 
 void    userauth(Authctxt *, char *);
@@ -330,6 +391,11 @@ static char *authmethods_get(void);
 
 Authmethod authmethods[] = {
 #ifdef GSSAPI
+        {"gssapi-keyex",
+                userauth_gsskeyex,
+                NULL,
+                &options.gss_authentication,
+                NULL},
         {"gssapi-with-mic",
                 userauth_gssapi,
                 NULL,
@@ -657,25 +723,40 @@ userauth_gssapi(Authctxt *authctxt)
         static u_int mech = 0;
         OM_uint32 min;
         int r, ok = 0;
+        char *gss_host;
+
+        if (options.gss_server_identity)
+                gss_host = xstrdup(options.gss_server_identity);
+        else if (options.gss_trust_dns)
+                gss_host = remote_hostname(active_state);
+        else
+                gss_host = xstrdup(authctxt->host);
 
         /* Try one GSSAPI method at a time, rather than sending them all at
          * once. */
 
         if (gss_supported == NULL)
-                gss_indicate_mechs(&min, &gss_supported);
+                if (GSS_ERROR(gss_indicate_mechs(&min, &gss_supported))) {
+                        gss_supported = NULL;
+                        free(gss_host);
+                        return 0;
+                }
 
         /* Check to see if the mechanism is usable before we offer it */
         while (mech < gss_supported->count && !ok) {
                 /* My DER encoding requires length<128 */
                 if (gss_supported->elements[mech].length < 128 &&
                     ssh_gssapi_check_mechanism(&gssctxt,
-                    &gss_supported->elements[mech], authctxt->host)) {
+                    &gss_supported->elements[mech], gss_host,
+                    options.gss_client_identity)) {
                         ok = 1; /* Mechanism works */
                 } else {
                         mech++;
                 }
         }
 
+        free(gss_host);
+
         if (!ok)
                 return 0;
 
@@ -906,6 +987,54 @@ input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
         free(lang);
         return r;
 }
+
+int
+userauth_gsskeyex(Authctxt *authctxt)
+{
+        struct ssh *ssh = active_state; /* XXX */
+        struct sshbuf *b;
+        gss_buffer_desc gssbuf;
+        gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
+        OM_uint32 ms;
+        int r;
+
+        static int attempt = 0;
+        if (attempt++ >= 1)
+                return (0);
+
+        if (gss_kex_context == NULL) {
+                debug("No valid Key exchange context"); 
+                return (0);
+        }
+
+        if ((b = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        ssh_gssapi_buildmic(b, authctxt->server_user, authctxt->service,
+            "gssapi-keyex");
+
+        if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
+                fatal("%s: sshbuf_mutable_ptr failed", __func__);
+        gssbuf.length = sshbuf_len(b);
+
+        if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
+                sshbuf_free(b);
+                return (0);
+        }
+
+        if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+            (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+            (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+            (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+            (r = sshpkt_put_string(ssh, mic.value, mic.length)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0)
+                fatal("%s: %s", __func__, ssh_err(r));
+
+        sshbuf_free(b);
+        gss_release_buffer(&ms, &mic);
+
+        return (1);
+}
+
 #endif /* GSSAPI */
 
 int