1 files changed, 149 insertions, 5 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
index f64aae66a..c47fc31a6 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -80,8 +80,6 @@
 #endif
 
 /* import */
-extern char *client_version_string;
-extern char *server_version_string;
 extern Options options;
 
 /*
@@ -210,6 +208,11 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
         char *s, *all_key;
         int r, use_known_hosts_order = 0;
 
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+        char *orig = NULL, *gss = NULL;
+        char *gss_host = NULL;
+#endif
+
         xxx_host = host;
         xxx_hostaddr = hostaddr;
 
@@ -253,6 +256,41 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
                     compat_pkalg_proposal(options.hostkeyalgorithms);
         }
 
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+        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(ssh);
+                        /* Fall back to specified host if we are using proxy command
+                         * and can not use DNS on that socket */
+                        if (strcmp(gss_host, "UNKNOWN") == 0) {
+                                gss_host = xstrdup(host);
+                        }
+                } else {
+                        gss_host = xstrdup(host);
+                }
+
+                gss = ssh_gssapi_client_mechanisms(gss_host,
+                    options.gss_client_identity, options.gss_kex_algorithms);
+                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)
                 ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
                     options.rekey_interval);
@@ -271,16 +309,46 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
 # ifdef OPENSSL_HAS_ECC
         ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
 # endif
-#endif
+# ifdef GSSAPI
+        if (options.gss_keyex) {
+                ssh->kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
+                ssh->kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
+                ssh->kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_client;
+                ssh->kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_client;
+                ssh->kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_client;
+                ssh->kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_client;
+                ssh->kex->kex[KEX_GSS_C25519_SHA256] = kexgss_client;
+        }
+# endif
+#endif /* WITH_OPENSSL */
         ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
         ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client;
         ssh->kex->verify_host_key=&verify_host_key_callback;
 
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+        if (options.gss_keyex) {
+                ssh->kex->gss_deleg_creds = options.gss_deleg_creds;
+                ssh->kex->gss_trust_dns = options.gss_trust_dns;
+                ssh->kex->gss_client = options.gss_client_identity;
+                ssh->kex->gss_host = gss_host;
+        }
+#endif
+
         ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done);
 
         /* remove ext-info from the KEX proposals for rekeying */
         myproposal[PROPOSAL_KEX_ALGS] =
             compat_kex_proposal(options.kex_algorithms);
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+        /* 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(ssh->kex->my, myproposal)) != 0)
                 fatal("kex_prop2buf: %s", ssh_err(r));
 
@@ -377,6 +445,7 @@ static int input_gssapi_response(int type, u_int32_t, struct ssh *);
 static int input_gssapi_token(int type, u_int32_t, struct ssh *);
 static int input_gssapi_error(int, u_int32_t, struct ssh *);
 static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
+static int userauth_gsskeyex(struct ssh *);
 #endif
 
 void    userauth(struct ssh *, char *);
@@ -393,6 +462,11 @@ static char *authmethods_get(void);
 
 Authmethod authmethods[] = {
 #ifdef GSSAPI
+        {"gssapi-keyex",
+                userauth_gsskeyex,
+                NULL,
+                &options.gss_keyex,
+                NULL},
         {"gssapi-with-mic",
                 userauth_gssapi,
                 userauth_gssapi_cleanup,
@@ -763,12 +837,31 @@ userauth_gssapi(struct ssh *ssh)
         OM_uint32 min;
         int r, ok = 0;
         gss_OID mech = NULL;
+        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(ssh);
+                /* Fall back to specified host if we are using proxy command
+                 * and can not use DNS on that socket */
+                if (strcmp(gss_host, "UNKNOWN") == 0) {
+                        gss_host = authctxt->host;
+                }
+        } else {
+                gss_host = xstrdup(authctxt->host);
+        }
 
         /* Try one GSSAPI method at a time, rather than sending them all at
          * once. */
 
         if (authctxt->gss_supported_mechs == NULL)
-                gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
+                if (GSS_ERROR(gss_indicate_mechs(&min,
+                    &authctxt->gss_supported_mechs))) {
+                        authctxt->gss_supported_mechs = NULL;
+                        free(gss_host);
+                        return 0;
+                }
 
         /* Check to see whether the mechanism is usable before we offer it */
         while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
@@ -777,13 +870,15 @@ userauth_gssapi(struct ssh *ssh)
                     elements[authctxt->mech_tried];
                 /* My DER encoding requires length<128 */
                 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
-                    mech, authctxt->host)) {
+                    mech, gss_host, options.gss_client_identity)) {
                         ok = 1; /* Mechanism works */
                 } else {
                         authctxt->mech_tried++;
                 }
         }
 
+        free(gss_host);
+
         if (!ok || mech == NULL)
                 return 0;
 
@@ -1023,6 +1118,55 @@ input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
         free(lang);
         return r;
 }
+
+int
+userauth_gsskeyex(struct ssh *ssh)
+{
+        struct sshbuf *b = NULL;
+        Authctxt *authctxt = ssh->authctxt;
+        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 */
 
 static int