1 files changed, 58 insertions, 4 deletions

diff --git a/sshd.c b/sshd.c
index 60b2aaf73..d92f03aaf 100644
--- a/sshd.c
+++ b/sshd.c
@@ -817,8 +817,8 @@ notify_hostkeys(struct ssh *ssh)
         }
         debug3("%s: sent %u hostkeys", __func__, nkeys);
         if (nkeys == 0)
-                fatal("%s: no hostkeys", __func__);
-        if ((r = sshpkt_send(ssh)) != 0)
+                debug3("%s: no hostkeys", __func__);
+        else if ((r = sshpkt_send(ssh)) != 0)
                 sshpkt_fatal(ssh, r, "%s: send", __func__);
         sshbuf_free(buf);
 }
@@ -1852,7 +1852,8 @@ main(int ac, char **av)
                 free(fp);
         }
         accumulate_host_timing_secret(cfg, NULL);
-        if (!sensitive_data.have_ssh2_key) {
+        /* The GSSAPI key exchange can run without a host key */
+        if (!sensitive_data.have_ssh2_key && !options.gss_keyex) {
                 logit("sshd: no hostkeys available -- exiting.");
                 exit(1);
         }
@@ -2347,6 +2348,48 @@ do_ssh2_kex(struct ssh *ssh)
         myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
             list_hostkey_types());
 
+#if defined(GSSAPI) && defined(WITH_OPENSSL)
+        {
+        char *orig;
+        char *gss = NULL;
+        char *newstr = NULL;
+        orig = myproposal[PROPOSAL_KEX_ALGS];
+
+        /*
+         * If we don't have a host key, then there's no point advertising
+         * the other key exchange algorithms
+         */
+
+        if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
+                orig = NULL;
+
+        if (options.gss_keyex)
+                gss = ssh_gssapi_server_mechanisms();
+        else
+                gss = NULL;
+
+        if (gss && orig)
+                xasprintf(&newstr, "%s,%s", gss, orig);
+        else if (gss)
+                newstr = gss;
+        else if (orig)
+                newstr = orig;
+
+        /*
+         * If we've got GSSAPI mechanisms, then we've got the 'null' host
+         * key alg, but we can't tell people about it unless its the only
+         * host key algorithm we support
+         */
+        if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
+                myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
+
+        if (newstr)
+                myproposal[PROPOSAL_KEX_ALGS] = newstr;
+        else
+                fatal("No supported key exchange algorithms");
+        }
+#endif
+
         /* start key exchange */
         if ((r = kex_setup(ssh, myproposal)) != 0)
                 fatal("kex_setup: %s", ssh_err(r));
@@ -2362,7 +2405,18 @@ do_ssh2_kex(struct ssh *ssh)
 # ifdef OPENSSL_HAS_ECC
         kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
 # endif
-#endif
+# ifdef GSSAPI
+        if (options.gss_keyex) {
+                kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
+                kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
+                kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server;
+                kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server;
+                kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server;
+                kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server;
+                kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server;
+        }
+# endif
+#endif /* WITH_OPENSSL */
         kex->kex[KEX_C25519_SHA256] = kex_gen_server;
         kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server;
         kex->load_host_public_key=&get_hostkey_public_by_type;