feat: test null hostkey on ci

Signed-off-by: Gauravsingh Sisodia <xaerru@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/kex.c

@@ -796,6 +796,8 @@ int ssh_set_client_kex(ssh_session session)
     const char *wanted = NULL;
     int ok;
     int i;
+    bool gssapi_null_alg = false;
+    char *hostkeys = NULL;
 
     /* Skip if already set, for example for the rekey or when we do the guessing
      * it could have been already used to make some protocol decisions. */
@@ -831,6 +833,9 @@ int ssh_set_client_kex(ssh_session session)
         /* Prefix the default algorithms with gsskex algs */
         session->opts.wanted_methods[SSH_KEX] =
             ssh_prefix_without_duplicates(default_methods[SSH_KEX], gssapi_algs);
+
+        gssapi_null_alg = true;
+
         SAFE_FREE(gssapi_algs);
     }
 #endif
@@ -847,6 +852,15 @@ int ssh_set_client_kex(ssh_session session)
                 ssh_set_error_oom(session);
                 return SSH_ERROR;
             }
+            if (gssapi_null_alg) {
+                hostkeys = ssh_append_without_duplicates(client->methods[i], "null");
+                if (hostkeys == NULL) {
+                    ssh_set_error_oom(session);
+                    return SSH_ERROR;
+                }
+                SAFE_FREE(client->methods[i]);
+                client->methods[i] = hostkeys;
+            }
             continue;
         }
 

tests/client/CMakeLists.txt

@@ -46,7 +46,8 @@ if (WITH_GSSAPI AND GSSAPI_FOUND AND GSSAPI_TESTING)
     set(LIBSSH_CLIENT_TESTS
         ${LIBSSH_CLIENT_TESTS}
         torture_gssapi_auth
-        torture_gssapi_key_exchange)
+        torture_gssapi_key_exchange
+        torture_gssapi_key_exchange_null)
 endif()
 
 if (DEFAULT_C_NO_DEPRECATION_FLAGS)

tests/client/torture_gssapi_key_exchange_null.c

@@ -0,0 +1,136 @@
+#include "config.h"
+
+#define LIBSSH_STATIC
+
+#include "torture.h"
+#include <libssh/libssh.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <gssapi.h>
+#include <pwd.h>
+
+static int
+sshd_setup(void **state)
+{
+    struct torture_state *s = NULL;
+    torture_setup_sshd_server(state, false);
+
+    s = *state;
+    s->disable_hostkeys = true;
+
+    /* Temporary kerberos server */
+    torture_setup_kdc_server(
+        state,
+        "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");
+
+    torture_update_sshd_config(state,
+                               "GSSAPIAuthentication yes\n"
+                               "GSSAPIKeyExchange yes\n");
+
+    torture_teardown_kdc_server(state);
+    return 0;
+}
+
+static int
+sshd_teardown(void **state)
+{
+    assert_non_null(state);
+
+    torture_teardown_sshd_server(state);
+
+    return 0;
+}
+
+static int
+session_setup(void **state)
+{
+    struct torture_state *s = *state;
+    int verbosity = torture_libssh_verbosity();
+    struct passwd *pwd = NULL;
+    int rc;
+    bool b = false;
+
+    pwd = getpwnam("bob");
+    assert_non_null(pwd);
+
+    rc = setuid(pwd->pw_uid);
+    assert_return_code(rc, errno);
+
+    s->ssh.session = ssh_new();
+    assert_non_null(s->ssh.session);
+
+    ssh_options_set(s->ssh.session, SSH_OPTIONS_LOG_VERBOSITY, &verbosity);
+    ssh_options_set(s->ssh.session, SSH_OPTIONS_HOST, TORTURE_SSH_SERVER);
+
+    ssh_options_set(s->ssh.session, SSH_OPTIONS_USER, TORTURE_SSH_USER_ALICE);
+
+    /* 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 torture_state *s = *state;
+
+    assert_non_null(s);
+
+    ssh_disconnect(s->ssh.session);
+    ssh_free(s->ssh.session);
+
+    return 0;
+}
+
+static void
+torture_gssapi_key_exchange_null(void **state)
+{
+    struct torture_state *s = *state;
+    ssh_session session = s->ssh.session;
+    int rc;
+    bool t = true;
+
+    /* Valid */
+    torture_setup_kdc_server(
+        state,
+        "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_int_equal(rc, 0);
+    torture_teardown_kdc_server(state);
+}
+
+int
+torture_run_tests(void)
+{
+    int rc;
+    struct CMUnitTest tests[] = {
+        cmocka_unit_test_setup_teardown(torture_gssapi_key_exchange_null,
+                                        session_setup,
+                                        session_teardown),
+    };
+
+    ssh_init();
+
+    torture_filter_tests(tests);
+    rc = cmocka_run_group_tests(tests, sshd_setup, sshd_teardown);
+    ssh_finalize();
+
+    pthread_exit((void *)&rc);
+}

tests/ssh_ping.c

@@ -75,6 +75,11 @@ int main(int argc, char **argv)
         goto out;
     }
 
+    rc = ssh_options_set(session, SSH_OPTIONS_GSSAPI_KEY_EXCHANGE, "gss-group14-sha256-");
+    if (rc < 0) {
+        goto out;
+    }
+
     rc = ssh_connect(session);
     if (rc != SSH_OK) {
         fprintf(stderr, "Connection failed : %s\n", ssh_get_error(session));

tests/torture.c

@@ -657,6 +657,8 @@ void torture_setup_socket_dir(void **state)
 
     snprintf(s->srv_config, len, "%s/%s", p, TORTURE_SSHD_CONFIG);
 
+    s->disable_hostkeys = false;
+
     setenv("SOCKET_WRAPPER_DIR", p, 1);
     setenv("SOCKET_WRAPPER_DEFAULT_IFACE", "170", 1);
     env = getenv("TORTURE_GENERATE_PCAP");
@@ -975,6 +977,16 @@ 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) {

tests/torture.h

@@ -80,6 +80,7 @@ struct torture_state {
     char *srv1_pidfile;
     char *srv1_config;
     bool srv_pam;
+    bool disable_hostkeys;
     char *srv_additional_config;
     struct {
         ssh_session session;