knownhosts: Check if the hosts file exists

Fixes T135

Reported-by: Jan Pazdziora <jpazdziora@redhat.com>
Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>

src/knownhosts.c

@@ -557,6 +557,7 @@ enum ssh_known_hosts_e ssh_session_has_known_hosts_entry(ssh_session session)
     struct ssh_list *entry_list = NULL;
     struct ssh_iterator *it = NULL;
     char *host_port = NULL;
+    bool ok;
     int rc;
 
     if (session->opts.knownhosts == NULL) {
@@ -569,6 +570,25 @@ enum ssh_known_hosts_e ssh_session_has_known_hosts_entry(ssh_session session)
         }
     }
 
+    if (session->opts.knownhosts == NULL &&
+        session->opts.global_knownhosts == NULL) {
+            return SSH_KNOWN_HOSTS_NOT_FOUND;
+    }
+
+    if (session->opts.knownhosts != NULL) {
+        ok = ssh_file_readaccess_ok(session->opts.knownhosts);
+        if (!ok) {
+            return SSH_KNOWN_HOSTS_NOT_FOUND;
+        }
+    }
+
+    if (session->opts.global_knownhosts != NULL) {
+        ok = ssh_file_readaccess_ok(session->opts.global_knownhosts);
+        if (!ok) {
+            return SSH_KNOWN_HOSTS_NOT_FOUND;
+        }
+    }
+
     host_port = ssh_session_get_host_port(session);
     if (host_port == NULL) {
         return SSH_KNOWN_HOSTS_ERROR;

tests/unittests/torture_knownhosts_parsing.c

@@ -256,6 +256,7 @@ static void torture_knownhosts_read_file(void **state)
     ssh_list_free(entry_list);
 }
 
+#ifndef _WIN32 /* There is no /dev/null on Windows */
 static void torture_knownhosts_host_exists(void **state)
 {
     const char *knownhosts_file = *state;
@@ -365,6 +366,7 @@ torture_knownhosts_algorithms_global(void **state)
 
     ssh_free(session);
 }
+#endif
 
 int torture_run_tests(void) {
     int rc;
@@ -378,6 +380,7 @@ int torture_run_tests(void) {
         cmocka_unit_test_setup_teardown(torture_knownhosts_read_file,
                                         setup_knownhosts_file,
                                         teardown_knownhosts_file),
+#ifndef _WIN32
         cmocka_unit_test_setup_teardown(torture_knownhosts_host_exists,
                                         setup_knownhosts_file,
                                         teardown_knownhosts_file),
@@ -390,6 +393,7 @@ int torture_run_tests(void) {
         cmocka_unit_test_setup_teardown(torture_knownhosts_algorithms_global,
                                         setup_knownhosts_file,
                                         teardown_knownhosts_file),
+#endif
     };
 
     ssh_init();