feat: add null hostkey for server

fix: skip gssapi tests in fips mode fix: skip gssapi_key_exchange_null test on ubuntu and tumbleweed fix: return early when rc != 0 to show error tests: replace int asserts by ssh return code asserts fix: add fatal error when hostkeys are not found and gssapi kex is not enabled ci: add comment linking gssapi null kex bug in ubuntu and tumbleweed fix: don't specify hostkeys in config instead of deleting files tests: assert kex method was null refactor: remove redundant include refactor: better error message fix: check null before accessing in gssapi.c fix: allow setting no hostkeys Signed-off-by: Gauravsingh Sisodia <xaerru@gmail.com> Reviewed-by: Jakub Jelen <jjelen@redhat.com> Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
2026-02-04 12:20:42 +09:00 · 2024-08-29 14:03:12 +00:00
parent fd1c3e8878
commit c1aab9903f
21 changed files with 579 additions and 117 deletions
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -83,6 +83,11 @@ workflow:
 .tumbleweed:
  extends: .tests
  image: $CI_REGISTRY/$BUILD_IMAGES_PROJECT:$TUMBLEWEED_BUILD
+  script:
+    # torture_gssapi_key_exchange_null is excluded because of a bug (https://issues.redhat.com/browse/RHEL-55740)
+    - cmake $CMAKE_OPTIONS $CMAKE_ADDITIONAL_OPTIONS .. &&
+      make -j$(nproc) &&
+      ctest --output-on-failure -E "^torture_gssapi_key_exchange_null$"

 .centos:
  extends: .tests
@@ -504,6 +509,11 @@ fedora/abidiff:
 ubuntu/openssl_3.0.x/x86_64:
  image: $CI_REGISTRY/$BUILD_IMAGES_PROJECT:$UBUNTU_BUILD
  extends: .tests
+  script:
+    # torture_gssapi_key_exchange_null is excluded because of a bug (https://issues.redhat.com/browse/RHEL-55740)
+    - cmake $CMAKE_OPTIONS $CMAKE_ADDITIONAL_OPTIONS .. &&
+      make -j$(nproc) &&
+      ctest --output-on-failure -E "^torture_gssapi_key_exchange_null$"


 ###############################################################################
--- a/src/auth.c
+++ b/src/auth.c
@@ -2456,7 +2456,7 @@ pending:
 }

 /**
- * @brief Try to authenticate through the "gssapi-with-keyex" method.
+ * @brief Try to authenticate through the "gssapi-keyex" method.
 *
 * @param[in] session The ssh session to use.
 *
@@ -2503,7 +2503,7 @@ int ssh_userauth_gssapi_keyex(ssh_session session)
    } else if (rc == SSH_ERROR) {
        return SSH_AUTH_ERROR;
    }
-    SSH_LOG(SSH_LOG_DEBUG, "Authenticating with gssapi-with-keyex");
+    SSH_LOG(SSH_LOG_DEBUG, "Authenticating with gssapi-keyex");

    session->auth.current_method = SSH_AUTH_METHOD_GSSAPI_KEYEX;
    session->auth.state = SSH_AUTH_STATE_NONE;
--- a/src/bind.c
+++ b/src/bind.c
@@ -245,9 +245,14 @@ int ssh_bind_listen(ssh_bind sshbind)
        sshbind->ecdsa == NULL &&
        sshbind->ed25519 == NULL) {
        rc = ssh_bind_import_keys(sshbind);
-        if (rc != SSH_OK) {
+        if (rc == SSH_ERROR) {
+            if (!sshbind->gssapi_key_exchange) {
+                ssh_set_error(sshbind, SSH_FATAL,
+                            "No hostkeys found");
                return SSH_ERROR;
            }
+            SSH_LOG(SSH_LOG_DEBUG, "No hostkeys found: Using \"null\" hostkey algorithm");
+        }
    }

    if (sshbind->bindfd == SSH_INVALID_SOCKET) {
@@ -467,6 +472,7 @@ int ssh_bind_accept_fd(ssh_bind sshbind, ssh_session session, socket_t fd)
    session->opts.gssapi_key_exchange = sshbind->gssapi_key_exchange;

    if (sshbind->gssapi_key_exchange_algs != NULL) {
+        SAFE_FREE(session->opts.gssapi_key_exchange_algs);
        session->opts.gssapi_key_exchange_algs = strdup(sshbind->gssapi_key_exchange_algs);
        if (session->opts.gssapi_key_exchange_algs == NULL) {
            ssh_set_error_oom(sshbind);
@@ -519,9 +525,14 @@ int ssh_bind_accept_fd(ssh_bind sshbind, ssh_session session, socket_t fd)
        sshbind->ecdsa == NULL &&
        sshbind->ed25519 == NULL) {
        rc = ssh_bind_import_keys(sshbind);
-        if (rc != SSH_OK) {
+        if (rc == SSH_ERROR) {
+            if (!sshbind->gssapi_key_exchange) {
+                ssh_set_error(sshbind, SSH_FATAL,
+                            "No hostkeys found");
                return SSH_ERROR;
            }
+            SSH_LOG(SSH_LOG_DEBUG, "No hostkeys found: Using \"null\" hostkey algorithm");
+        }
    }

 #ifdef HAVE_ECC
--- a/src/dh-gss.c
+++ b/src/dh-gss.c
@@ -338,11 +338,6 @@ int ssh_server_gss_dh_process_init(ssh_session session, ssh_buffer packet)
        goto error;
    }

-    rc = ssh_get_key_params(session, &privkey, &digest);
-    if (rc != SSH_OK) {
-        goto error;
-    }
-
    rc = ssh_dh_compute_shared_secret(crypto->dh_ctx,
                                      DH_SERVER_KEYPAIR, DH_CLIENT_KEYPAIR,
                                      &crypto->shared_secret);
@@ -351,12 +346,18 @@ int ssh_server_gss_dh_process_init(ssh_session session, ssh_buffer packet)
        ssh_set_error(session, SSH_FATAL, "Could not generate shared secret");
        goto error;
    }
+
+    /* Also imports next_crypto->server_pubkey
+     * Can give error when using null hostkey */
+    ssh_get_key_params(session, &privkey, &digest);
+
    rc = ssh_make_sessionid(session);
    if (rc != SSH_OK) {
        ssh_set_error(session, SSH_FATAL, "Could not create a session id");
        goto error;
    }

+    if (strncmp(crypto->kex_methods[SSH_HOSTKEYS], "null", 4) != 0) {
        rc = ssh_dh_get_next_server_publickey_blob(session, &server_pubkey_blob);
        if (rc != SSH_OK) {
            goto error;
@@ -377,6 +378,7 @@ int ssh_server_gss_dh_process_init(ssh_session session, ssh_buffer packet)
        }
        SSH_LOG(SSH_LOG_DEBUG, "Sent SSH2_MSG_KEXGSS_HOSTKEY");
        SSH_STRING_FREE(server_pubkey_blob);
+    }

    rc = ssh_dh_keypair_get_keys(crypto->dh_ctx, DH_SERVER_KEYPAIR,
                                 NULL, &server_pubkey);
--- a/src/gssapi.c
+++ b/src/gssapi.c
@@ -727,6 +727,10 @@ ssh_gssapi_check_client_config(ssh_session session)

    for (i = 0; i < supported->count; ++i){
        gssapi = calloc(1, sizeof(struct ssh_gssapi_struct));
+        if (gssapi == NULL) {
+            ssh_set_error_oom(session);
+            return SSH_ERROR;
+        }
        gssapi->server_creds = GSS_C_NO_CREDENTIAL;
        gssapi->client_creds = GSS_C_NO_CREDENTIAL;
        gssapi->ctx = GSS_C_NO_CONTEXT;
@@ -786,7 +790,7 @@ ssh_gssapi_check_client_config(ssh_session session)
        SSH_LOG(SSH_LOG_DEBUG, "Supported mech %zu: %s", i, ptr);
        free(ptr);

-        /* If any one is configured then return successfully */
+        /* If atleast one mechanism is configured then return successfully */
        ret = SSH_OK;

 end:
--- a/src/kex.c
+++ b/src/kex.c
@@ -811,7 +811,7 @@ int ssh_set_client_kex(ssh_session session)
        return SSH_ERROR;
    }
 #ifdef WITH_GSSAPI
-    if (session->opts.gssapi_key_exchange) {
+    if (session->opts.gssapi_key_exchange && !ssh_fips_mode()) {
        char *gssapi_algs = NULL;

        ok = ssh_gssapi_init(session);
@@ -825,7 +825,7 @@ int ssh_set_client_kex(ssh_session session)
            return SSH_ERROR;
        }

-        gssapi_algs = ssh_gssapi_kex_mechs(session, session->opts.gssapi_key_exchange_algs ? session->opts.gssapi_key_exchange_algs : GSSAPI_KEY_EXCHANGE_SUPPORTED);
+        gssapi_algs = ssh_gssapi_kex_mechs(session, session->opts.gssapi_key_exchange_algs);
        if (gssapi_algs == NULL) {
            return SSH_ERROR;
        }
@@ -1488,15 +1488,15 @@ int ssh_make_sessionid(ssh_session session)
        goto error;
    }

-    if (server_pubkey_blob == NULL && session->opts.gssapi_key_exchange) {
-        ssh_string_free(server_pubkey_blob);
+    if (server_pubkey_blob == NULL) {
+        if ((session->server && ssh_kex_is_gss(session->next_crypto)) ||
+             session->opts.gssapi_key_exchange) {
            server_pubkey_blob = ssh_string_new(0);
+            if (server_pubkey_blob == NULL) {
+                ssh_set_error_oom(session);
+                rc = SSH_ERROR;
+                goto error;
            }
-
-    if (session->server) {
-        if (server_pubkey_blob == NULL && ssh_kex_is_gss(session->next_crypto)) {
-            ssh_string_free(server_pubkey_blob);
-            server_pubkey_blob = ssh_string_new(0);
        }
    }

--- a/src/options.c
+++ b/src/options.c
@@ -566,7 +566,7 @@ int ssh_options_set_algo(ssh_session session,
 *                to the server (int, 0 = false).
 *
 *              - SSH_OPTIONS_GSSAPI_KEY_EXCHANGE
- *                Set to true to do GSSAPI key exchange (bool).
+ *                Set to true to allow GSSAPI key exchange (bool).
 *
 *              - SSH_OPTIONS_GSSAPI_KEY_EXCHANGE_ALGS
 *                Set the GSSAPI key exchange method to be used (const char *,
@@ -1285,6 +1285,7 @@ int ssh_options_set(ssh_session session, enum ssh_options_e type,
                                  "GSSAPI key exchange algorithms not supported or invalid");
                    return -1;
                }
+                SAFE_FREE(session->opts.gssapi_key_exchange_algs);
                session->opts.gssapi_key_exchange_algs = ret;
            }
            break;
--- a/src/server.c
+++ b/src/server.c
@@ -141,10 +141,6 @@ int server_set_kex(ssh_session session)
                 ",%s", ssh_key_type_to_char(keytype));
    }

-    if (strlen(hostkeys) == 0) {
-        return -1;
-    }
-
    if (session->opts.wanted_methods[SSH_HOSTKEYS]) {
        allowed = session->opts.wanted_methods[SSH_HOSTKEYS];
    } else {
@@ -155,6 +151,7 @@ int server_set_kex(ssh_session session)
        }
    }

+    if (strlen(hostkeys) != 0) {
        /* It is expected for the list of allowed hostkeys to be ordered by
         * preference */
        kept = ssh_find_all_matching(hostkeys[0] == ',' ? hostkeys + 1 : hostkeys,
@@ -172,16 +169,16 @@ int server_set_kex(ssh_session session)
        if (rc < 0) {
            return -1;
        }
-
+    }
 #ifdef WITH_GSSAPI
-    if (session->opts.gssapi_key_exchange) {
+    if (session->opts.gssapi_key_exchange && !ssh_fips_mode()) {
        ok = ssh_gssapi_init(session);
        if (ok != SSH_OK) {
            ssh_set_error_oom(session);
            return SSH_ERROR;
        }

-        gssapi_algs = ssh_gssapi_kex_mechs(session, session->opts.gssapi_key_exchange_algs ? session->opts.gssapi_key_exchange_algs : GSSAPI_KEY_EXCHANGE_SUPPORTED);
+        gssapi_algs = ssh_gssapi_kex_mechs(session, session->opts.gssapi_key_exchange_algs);
        if (gssapi_algs == NULL) {
            return SSH_ERROR;
        }
@@ -191,6 +188,10 @@ int server_set_kex(ssh_session session)
        session->opts.wanted_methods[SSH_KEX] =
            ssh_prefix_without_duplicates(ssh_kex_get_default_methods(SSH_KEX), gssapi_algs);

+        if (strlen(hostkeys) == 0) {
+            session->opts.wanted_methods[SSH_HOSTKEYS] = strdup("null");
+        }
+
        SAFE_FREE(gssapi_algs);
    }
 #endif /* WITH_GSSAPI */
--- a/src/session.c
+++ b/src/session.c
@@ -160,6 +160,13 @@ ssh_session ssh_new(void)
        goto err;
    }

+#ifdef WITH_GSSAPI
+    session->opts.gssapi_key_exchange_algs = strdup(GSSAPI_KEY_EXCHANGE_SUPPORTED);
+    if (session->opts.gssapi_key_exchange_algs == NULL) {
+        goto err;
+    }
+#endif /* WITH_GSSAPI */
+
    id = strdup("%d/id_ed25519");
    if (id == NULL) {
        goto err;
--- a/tests/client/torture_gssapi_auth.c
+++ b/tests/client/torture_gssapi_auth.c
@@ -272,5 +272,11 @@ torture_run_tests(void)
    rc = cmocka_run_group_tests(tests, sshd_setup, sshd_teardown);
    ssh_finalize();

+    /* pthread_exit() won't return anything so error should be returned prior */
+    if (rc != 0) {
        return rc;
+    }
+
+    /* Required for freeing memory allocated by GSSAPI */
+    pthread_exit(NULL);
 }
--- a/tests/client/torture_gssapi_key_exchange.c
+++ b/tests/client/torture_gssapi_key_exchange.c
@@ -83,6 +83,11 @@ torture_gssapi_key_exchange(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    /* Valid */
    torture_setup_kdc_server(
        state,
@@ -97,7 +102,7 @@ torture_gssapi_key_exchange(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);
    torture_teardown_kdc_server(state);
 }

@@ -109,6 +114,11 @@ torture_gssapi_key_exchange_no_tgt(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    /* Don't run kinit */
    torture_setup_kdc_server(
        state,
@@ -124,7 +134,7 @@ torture_gssapi_key_exchange_no_tgt(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);

    assert_int_not_equal(session->current_crypto->kex_type, SSH_GSS_KEX_DH_GROUP14_SHA256);
    assert_int_not_equal(session->current_crypto->kex_type, SSH_GSS_KEX_DH_GROUP16_SHA512);
@@ -140,6 +150,11 @@ torture_gssapi_key_exchange_gss_group14_sha256(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    /* Valid */
    torture_setup_kdc_server(
        state,
@@ -157,7 +172,7 @@ torture_gssapi_key_exchange_gss_group14_sha256(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);

    assert_int_equal(session->current_crypto->kex_type, SSH_GSS_KEX_DH_GROUP14_SHA256);

@@ -172,6 +187,11 @@ torture_gssapi_key_exchange_gss_group16_sha512(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    /* Valid */
    torture_setup_kdc_server(
        state,
@@ -189,7 +209,7 @@ torture_gssapi_key_exchange_gss_group16_sha512(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);

    assert_true(session->current_crypto->kex_type == SSH_GSS_KEX_DH_GROUP16_SHA512);

@@ -204,6 +224,11 @@ torture_gssapi_key_exchange_auth(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    /* Valid */
    torture_setup_kdc_server(
        state,
@@ -218,7 +243,7 @@ torture_gssapi_key_exchange_auth(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);

    rc = ssh_userauth_gssapi_keyex(session);
    assert_int_equal(rc, SSH_AUTH_SUCCESS);
@@ -234,6 +259,11 @@ torture_gssapi_key_exchange_no_auth(void **state)
    int rc;
    bool f = false;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    /* Valid */
    torture_setup_kdc_server(
        state,
@@ -249,7 +279,7 @@ torture_gssapi_key_exchange_no_auth(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);

    /* Still try to do "gssapi-keyex" auth */
    rc = ssh_userauth_gssapi_keyex(session);
@@ -289,5 +319,11 @@ torture_run_tests(void)
    rc = cmocka_run_group_tests(tests, sshd_setup, sshd_teardown);
    ssh_finalize();

-    pthread_exit((void *)&rc);
+    /* pthread_exit() won't return anything so error should be returned prior */
+    if (rc != 0) {
+        return rc;
+    }
+
+    /* Required for freeing memory allocated by GSSAPI */
+    pthread_exit(NULL);
 }
--- a/tests/client/torture_gssapi_key_exchange_null.c
+++ b/tests/client/torture_gssapi_key_exchange_null.c
@@ -19,6 +19,7 @@ sshd_setup(void **state)
    s = *state;
    s->disable_hostkeys = true;

+    if (!ssh_fips_mode()) {
        /* Temporary kerberos server */
        torture_setup_kdc_server(
            state,
@@ -34,6 +35,7 @@ sshd_setup(void **state)
                                "GSSAPIKeyExchange yes\n");

        torture_teardown_kdc_server(state);
+    }
    return 0;
 }

@@ -98,6 +100,11 @@ torture_gssapi_key_exchange_null(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    /* Valid */
    torture_setup_kdc_server(
        state,
@@ -112,7 +119,10 @@ torture_gssapi_key_exchange_null(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(s->ssh.session, rc);
+
+    assert_string_equal(session->current_crypto->kex_methods[SSH_HOSTKEYS], "null");
+
    torture_teardown_kdc_server(state);
 }

@@ -132,5 +142,11 @@ torture_run_tests(void)
    rc = cmocka_run_group_tests(tests, sshd_setup, sshd_teardown);
    ssh_finalize();

-    pthread_exit((void *)&rc);
+    /* pthread_exit() won't return anything so error should be returned prior */
+    if (rc != 0) {
+        return rc;
+    }
+
+    /* Required for freeing memory allocated by GSSAPI */
+    pthread_exit(NULL);
 }
--- a/tests/server/CMakeLists.txt
+++ b/tests/server/CMakeLists.txt
@@ -20,7 +20,8 @@ if (WITH_GSSAPI AND GSSAPI_FOUND AND GSSAPI_TESTING)
        torture_gssapi_server_auth
        torture_gssapi_server_auth_cb
        torture_gssapi_server_delegation
-        torture_gssapi_server_key_exchange)
+        torture_gssapi_server_key_exchange
+        torture_gssapi_server_key_exchange_null)
 endif()

 include_directories(${libssh_SOURCE_DIR}/include
--- a/tests/server/test_server/test_server.c
+++ b/tests/server/test_server/test_server.c
@@ -145,9 +145,8 @@ int run_server(struct server_state_st *state)
    }

    if (state->host_key == NULL && state->rsa_key == NULL &&
-        state->ecdsa_key == NULL && state->ed25519_key) {
+        state->ecdsa_key == NULL && state->ed25519_key == NULL) {
        fprintf(stderr, "Missing host key\n");
-        goto out;
    }

    sshbind = ssh_bind_new();
@@ -211,7 +210,7 @@ int run_server(struct server_state_st *state)
                                  state->gssapi_key_exchange_algs);
        if (rc != 0) {
            fprintf(stderr,
-                    "Error setting GSSAPI key exchange: %s\n",
+                    "Error setting GSSAPI key exchange algorithms: %s\n",
                    ssh_get_error(sshbind));
            goto out;
        }
--- a/tests/server/torture_gssapi_server_auth.c
+++ b/tests/server/torture_gssapi_server_auth.c
@@ -452,5 +452,11 @@ torture_run_tests(void)
                                teardown_default_server);
    ssh_finalize();

+    /* pthread_exit() won't return anything so error should be returned prior */
+    if (rc != 0) {
        return rc;
+    }
+
+    /* Required for freeing memory allocated by GSSAPI */
+    pthread_exit(NULL);
 }
--- a/tests/server/torture_gssapi_server_auth_cb.c
+++ b/tests/server/torture_gssapi_server_auth_cb.c
@@ -476,5 +476,11 @@ torture_run_tests(void)
                                teardown_default_server);
    ssh_finalize();

+    /* pthread_exit() won't return anything so error should be returned prior */
+    if (rc != 0) {
        return rc;
+    }
+
+    /* Required for freeing memory allocated by GSSAPI */
+    pthread_exit(NULL);
 }
--- a/tests/server/torture_gssapi_server_delegation.c
+++ b/tests/server/torture_gssapi_server_delegation.c
@@ -372,5 +372,11 @@ torture_run_tests(void)
                                teardown_default_server);
    ssh_finalize();

+    /* pthread_exit() won't return anything so error should be returned prior */
+    if (rc != 0) {
        return rc;
+    }
+
+    /* Required for freeing memory allocated by GSSAPI */
+    pthread_exit(NULL);
 }
--- a/tests/server/torture_gssapi_server_key_exchange.c
+++ b/tests/server/torture_gssapi_server_key_exchange.c
@@ -286,6 +286,11 @@ torture_gssapi_server_key_exchange(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    assert_non_null(tss);

    s = tss->state;
@@ -322,6 +327,11 @@ torture_gssapi_server_key_exchange_no_tgt(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    assert_non_null(tss);

    s = tss->state;
@@ -345,7 +355,7 @@ torture_gssapi_server_key_exchange_no_tgt(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);

    assert_int_not_equal(session->current_crypto->kex_type, SSH_GSS_KEX_DH_GROUP14_SHA256);
    assert_int_not_equal(session->current_crypto->kex_type, SSH_GSS_KEX_DH_GROUP16_SHA512);
@@ -362,6 +372,11 @@ torture_gssapi_server_key_exchange_gss_group14_sha256(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    assert_non_null(tss);

    s = tss->state;
@@ -387,7 +402,7 @@ torture_gssapi_server_key_exchange_gss_group14_sha256(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);

    assert_int_equal(session->current_crypto->kex_type, SSH_GSS_KEX_DH_GROUP14_SHA256);

@@ -403,6 +418,11 @@ torture_gssapi_server_key_exchange_gss_group16_sha512(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    assert_non_null(tss);

    s = tss->state;
@@ -428,7 +448,7 @@ torture_gssapi_server_key_exchange_gss_group16_sha512(void **state)
    assert_ssh_return_code(s->ssh.session, rc);

    rc = ssh_connect(session);
-    assert_int_equal(rc, 0);
+    assert_ssh_return_code(session, rc);

    assert_int_equal(session->current_crypto->kex_type, SSH_GSS_KEX_DH_GROUP16_SHA512);

@@ -444,6 +464,11 @@ torture_gssapi_server_key_exchange_auth(void **state)
    int rc;
    bool t = true;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    assert_non_null(tss);

    s = tss->state;
@@ -483,6 +508,11 @@ torture_gssapi_server_key_exchange_no_auth(void **state)
    int rc;
    bool f = false;

+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
    assert_non_null(tss);

    s = tss->state;
@@ -547,5 +577,11 @@ torture_run_tests(void)
                                teardown_default_server);
    ssh_finalize();

-    pthread_exit((void *)&rc);
+    /* pthread_exit() won't return anything so error should be returned prior */
+    if (rc != 0) {
+        return rc;
+    }
+
+    /* Required for freeing memory allocated by GSSAPI */
+    pthread_exit(NULL);
 }
--- a/tests/server/torture_gssapi_server_key_exchange_null.c
+++ b/tests/server/torture_gssapi_server_key_exchange_null.c
@@ -0,0 +1,305 @@
+#include "config.h"
+
+#define LIBSSH_STATIC
+
+#include <errno.h>
+#include <pwd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "libssh/libssh.h"
+#include "torture.h"
+
+#include "test_server.h"
+#include "default_cb.h"
+
+struct test_server_st {
+    struct torture_state *state;
+    struct server_state_st *ss;
+    char *cwd;
+};
+
+static void
+free_test_server_state(void **state)
+{
+    struct test_server_st *tss = *state;
+
+    torture_free_state(tss->state);
+    SAFE_FREE(tss);
+}
+
+static void
+setup_config(void **state)
+{
+    struct torture_state *s = NULL;
+    struct server_state_st *ss = NULL;
+    struct test_server_st *tss = NULL;
+
+    char sshd_path[1024];
+    char log_file[1024];
+    char kdc_env[255] = {0};
+    int rc;
+
+    assert_non_null(state);
+
+    tss = (struct test_server_st *)calloc(1, sizeof(struct test_server_st));
+    assert_non_null(tss);
+
+    torture_setup_socket_dir((void **)&s);
+    assert_non_null(s->socket_dir);
+    assert_non_null(s->gss_dir);
+
+    torture_set_kdc_env_str(s->gss_dir, kdc_env, sizeof(kdc_env));
+    torture_set_env_from_str(kdc_env);
+
+    /* Set the default interface for the server */
+    setenv("SOCKET_WRAPPER_DEFAULT_IFACE", "10", 1);
+    setenv("PAM_WRAPPER", "1", 1);
+
+    snprintf(sshd_path, sizeof(sshd_path), "%s/sshd", s->socket_dir);
+
+    rc = mkdir(sshd_path, 0755);
+    assert_return_code(rc, errno);
+
+    snprintf(log_file, sizeof(log_file), "%s/sshd/log", s->socket_dir);
+
+    /* Create default server state */
+    ss = (struct server_state_st *)calloc(1, sizeof(struct server_state_st));
+    assert_non_null(ss);
+
+    ss->address = strdup("127.0.0.10");
+    assert_non_null(ss->address);
+
+    ss->port = 22;
+
+    /* not to mix up the client and server messages */
+    ss->verbosity = torture_libssh_verbosity();
+    ss->log_file = strdup(log_file);
+
+    ss->auth_methods = SSH_AUTH_METHOD_GSSAPI_KEYEX;
+
+#ifdef WITH_PCAP
+    ss->with_pcap = 1;
+    ss->pcap_file = strdup(s->pcap_file);
+    assert_non_null(ss->pcap_file);
+#endif
+
+    /* TODO make configurable */
+    ss->max_tries = 3;
+    ss->error = 0;
+
+    /* Use the default session handling function */
+    ss->handle_session = default_handle_session_cb;
+    assert_non_null(ss->handle_session);
+
+    /* Do not use global configuration */
+    ss->parse_global_config = false;
+
+    /* Enable GSSAPI key exchange */
+    ss->gssapi_key_exchange = true;
+    ss->gssapi_key_exchange_algs = "gss-group14-sha256-,gss-group16-sha512-";
+
+    tss->state = s;
+    tss->ss = ss;
+
+    *state = tss;
+}
+
+static int
+setup_default_server(void **state)
+{
+    struct torture_state *s = NULL;
+    struct server_state_st *ss = NULL;
+    struct test_server_st *tss = NULL;
+    char pid_str[1024] = {0};
+    pid_t pid;
+    /*int rc;*/
+
+    setup_config(state);
+
+    tss = *state;
+    ss = tss->ss;
+    s = tss->state;
+
+    setenv("NSS_WRAPPER_HOSTNAME", "server.libssh.site", 1);
+    /* Start the server using the default values */
+    pid = fork_run_server(ss, free_test_server_state, &tss);
+    if (pid < 0) {
+        fail();
+    }
+
+    snprintf(pid_str, sizeof(pid_str), "%d", pid);
+
+    torture_write_file(s->srv_pidfile, (const char *)pid_str);
+
+    setenv("SOCKET_WRAPPER_DEFAULT_IFACE", "21", 1);
+    unsetenv("PAM_WRAPPER");
+
+    /* Wait until the sshd is ready to accept connections */
+    /*rc = torture_wait_for_daemon(5);*/
+    /*assert_int_equal(rc, 0);*/
+
+    *state = tss;
+
+    return 0;
+}
+
+static int
+teardown_default_server(void **state)
+{
+    struct torture_state *s = NULL;
+    struct server_state_st *ss = NULL;
+    struct test_server_st *tss = NULL;
+
+    tss = *state;
+    assert_non_null(tss);
+
+    s = tss->state;
+    assert_non_null(s);
+
+    ss = tss->ss;
+    assert_non_null(ss);
+
+    /* This function can be reused */
+    torture_teardown_sshd_server((void **)&s);
+
+    free_server_state(tss->ss);
+    SAFE_FREE(tss->ss);
+    SAFE_FREE(tss);
+
+    return 0;
+}
+
+static int
+session_setup(void **state)
+{
+    struct test_server_st *tss = *state;
+    struct torture_state *s = NULL;
+    int verbosity = torture_libssh_verbosity();
+    char *cwd = NULL;
+    bool b = false;
+    int rc;
+
+    assert_non_null(tss);
+
+    /* Make sure we do not test the agent */
+    unsetenv("SSH_AUTH_SOCK");
+
+    cwd = torture_get_current_working_dir();
+    assert_non_null(cwd);
+
+    tss->cwd = cwd;
+
+    s = tss->state;
+    assert_non_null(s);
+
+    s->ssh.session = ssh_new();
+    assert_non_null(s->ssh.session);
+
+    rc = ssh_options_set(s->ssh.session, SSH_OPTIONS_LOG_VERBOSITY, &verbosity);
+    assert_ssh_return_code(s->ssh.session, rc);
+    rc = ssh_options_set(s->ssh.session, SSH_OPTIONS_HOST, TORTURE_SSH_SERVER);
+    assert_ssh_return_code(s->ssh.session, rc);
+    rc = ssh_options_set(s->ssh.session,
+                         SSH_OPTIONS_USER,
+                         TORTURE_SSH_USER_ALICE);
+    assert_int_equal(rc, SSH_OK);
+    /* Make sure no other configuration options from system will get used */
+    rc = ssh_options_set(s->ssh.session, SSH_OPTIONS_PROCESS_CONFIG, &b);
+    assert_ssh_return_code(s->ssh.session, rc);
+
+    return 0;
+}
+
+static int
+session_teardown(void **state)
+{
+    struct test_server_st *tss = *state;
+    struct torture_state *s = NULL;
+    int rc = 0;
+
+    assert_non_null(tss);
+
+    s = tss->state;
+    assert_non_null(s);
+
+    ssh_disconnect(s->ssh.session);
+    ssh_free(s->ssh.session);
+
+    rc = torture_change_dir(tss->cwd);
+    assert_int_equal(rc, 0);
+
+    SAFE_FREE(tss->cwd);
+
+    return 0;
+}
+
+
+static void
+torture_gssapi_server_key_exchange_null(void **state)
+{
+    struct test_server_st *tss = *state;
+    struct torture_state *s = NULL;
+    ssh_session session;
+    int rc;
+    bool t = true;
+
+    /* Skip test if in FIPS mode */
+    if (ssh_fips_mode()) {
+        skip();
+    }
+
+    assert_non_null(tss);
+
+    s = tss->state;
+    assert_non_null(s);
+
+    session = s->ssh.session;
+    assert_non_null(session);
+
+    /* Valid */
+    torture_setup_kdc_server(
+        (void **)&s,
+        "kadmin.local addprinc -randkey host/server.libssh.site\n"
+        "kadmin.local ktadd -k $(dirname $0)/d/ssh.keytab host/server.libssh.site\n"
+        "kadmin.local addprinc -pw bar alice\n"
+        "kadmin.local list_principals",
+
+        "echo bar | kinit alice");
+
+    rc = ssh_options_set(s->ssh.session, SSH_OPTIONS_GSSAPI_KEY_EXCHANGE, &t);
+    assert_ssh_return_code(s->ssh.session, rc);
+
+    rc = ssh_connect(session);
+    assert_ssh_return_code(s->ssh.session, rc);
+
+    assert_string_equal(session->current_crypto->kex_methods[SSH_HOSTKEYS], "null");
+
+    torture_teardown_kdc_server((void **)&s);
+}
+
+int
+torture_run_tests(void)
+{
+    int rc;
+    struct CMUnitTest tests[] = {
+        cmocka_unit_test_setup_teardown(torture_gssapi_server_key_exchange_null,
+                                        session_setup,
+                                        session_teardown),
+    };
+
+    ssh_init();
+    torture_filter_tests(tests);
+    rc = cmocka_run_group_tests(tests,
+                                setup_default_server,
+                                teardown_default_server);
+    ssh_finalize();
+
+    /* pthread_exit() won't return anything so error should be returned prior */
+    if (rc != 0) {
+        return rc;
+    }
+
+    /* Required for freeing memory allocated by GSSAPI */
+    pthread_exit(NULL);
+}
--- a/tests/ssh_ping.c
+++ b/tests/ssh_ping.c
@@ -29,6 +29,9 @@ int main(int argc, char **argv)
    const char *hostkeys = NULL;
    const char *kex = NULL;
    int rc = 1;
+#ifdef WITH_GSSAPI
+    bool t = true;
+#endif /* WITH_GSSAPI */

    bool process_config = false;

@@ -75,10 +78,12 @@ int main(int argc, char **argv)
        goto out;
    }

-    rc = ssh_options_set(session, SSH_OPTIONS_GSSAPI_KEY_EXCHANGE, "gss-group14-sha256-");
+#ifdef WITH_GSSAPI
+    rc = ssh_options_set(session, SSH_OPTIONS_GSSAPI_KEY_EXCHANGE, &t);
    if (rc < 0) {
        goto out;
    }
+#endif /* WITH_GSSAPI */

    rc = ssh_connect(session);
    if (rc != SSH_OK) {
--- a/tests/torture.c
+++ b/tests/torture.c
@@ -819,9 +819,9 @@ torture_setup_create_sshd_config(void **state, bool pam, bool second_sshd)
        "Port 22\n"
        "ListenAddress %s\n"
        "ListenAddress %s\n"
-        "HostKey %s\n" /* ed25519 HostKey */
-        "HostKey %s\n" /* RSA HostKey */
-        "HostKey %s\n" /* ECDSA HostKey */
+        "%s %s\n" /* ed25519 HostKey */
+        "%s %s\n" /* RSA HostKey */
+        "%s %s\n" /* ECDSA HostKey */
        "\n"
        "TrustedUserCAKeys %s\n"
        "\n"
@@ -860,8 +860,8 @@ torture_setup_create_sshd_config(void **state, bool pam, bool second_sshd)
        "Port 22\n"
        "ListenAddress %s\n"
        "ListenAddress %s\n"
-        "HostKey %s\n" /* RSA HostKey */
-        "HostKey %s\n" /* ECDSA HostKey */
+        "%s %s\n" /* RSA HostKey */
+        "%s %s\n" /* ECDSA HostKey */
        "\n"
        "TrustedUserCAKeys %s\n" /* Trusted CA */
        "\n"
@@ -977,16 +977,6 @@ torture_setup_create_sshd_config(void **state, bool pam, bool second_sshd)
                           torture_get_testkey(SSH_KEYTYPE_ECDSA_P521, 0));
        torture_write_file(trusted_ca_pubkey, torture_rsa_certauth_pub);
    }
-    if (s->disable_hostkeys) {
-        char ss[1000] = {0};
-        rc = snprintf(ss, sizeof(ss), "rm %s/sshd/ssh_host_ecdsa_key %s/sshd/ssh_host_ed25519_key %s/sshd/ssh_host_rsa_key", s->socket_dir, s->socket_dir, s->socket_dir);
-        if (rc < 0 || rc >= (int)sizeof(ss)) {
-            fail_msg("snprintf failed");
-        }
-
-        rc = system(ss);
-        assert_int_equal(rc, SSH_OK);
-    }

    sftp_server = getenv("TORTURE_SFTP_SERVER");
    if (sftp_server == NULL) {
@@ -1009,8 +999,22 @@ torture_setup_create_sshd_config(void **state, bool pam, bool second_sshd)
                 fips_config_string,
                 second_sshd ? TORTURE_SSHD_SRV1_IPV4 : TORTURE_SSHD_SRV_IPV4,
                 second_sshd ? TORTURE_SSHD_SRV1_IPV6 : TORTURE_SSHD_SRV_IPV6,
-                 rsa_hostkey,
-                 ecdsa_hostkey,
+                 "HostKey", rsa_hostkey,
+                 "HostKey", ecdsa_hostkey,
+                 trusted_ca_pubkey,
+                 sftp_server,
+                 usepam,
+                 additional_config,
+                 second_sshd ? s->srv1_pidfile : s->srv_pidfile);
+    } else if (s->disable_hostkeys) {
+        snprintf(sshd_config,
+                 sizeof(sshd_config),
+                 config_string,
+                 second_sshd ? TORTURE_SSHD_SRV1_IPV4 : TORTURE_SSHD_SRV_IPV4,
+                 second_sshd ? TORTURE_SSHD_SRV1_IPV6 : TORTURE_SSHD_SRV_IPV6,
+                 "", "",
+                 "", "",
+                 "", "",
                 trusted_ca_pubkey,
                 sftp_server,
                 usepam,
@@ -1022,9 +1026,9 @@ torture_setup_create_sshd_config(void **state, bool pam, bool second_sshd)
                 config_string,
                 second_sshd ? TORTURE_SSHD_SRV1_IPV4 : TORTURE_SSHD_SRV_IPV4,
                 second_sshd ? TORTURE_SSHD_SRV1_IPV6 : TORTURE_SSHD_SRV_IPV6,
-                 ed25519_hostkey,
-                 rsa_hostkey,
-                 ecdsa_hostkey,
+                 "HostKey", ed25519_hostkey,
+                 "HostKey", rsa_hostkey,
+                 "HostKey", ecdsa_hostkey,
                 trusted_ca_pubkey,
                 sftp_server,
                 usepam,