pki: Search OpenSSH header not only at the beginning

Try to find the OpenSSH private key header not only at the beginning of
the file.  This makes the parser to skip comments and white spaces.

Fixes: T76
Fixes: T123

Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/pki.c

@@ -724,7 +724,7 @@ int ssh_pki_import_privkey_base64(const char *b64_key,
                                   ssh_key *pkey)
 {
     ssh_key key;
-    int cmp;
+    char *openssh_header = NULL;
 
     if (b64_key == NULL || pkey == NULL) {
         return SSH_ERROR;
@@ -739,9 +739,9 @@ int ssh_pki_import_privkey_base64(const char *b64_key,
             passphrase ? "true" : "false");
 
     /* Test for OpenSSH key format first */
-    cmp = strncmp(b64_key, OPENSSH_HEADER_BEGIN, strlen(OPENSSH_HEADER_BEGIN));
-    if (cmp == 0) {
-        key = ssh_pki_openssh_privkey_import(b64_key,
+    openssh_header = strstr(b64_key, OPENSSH_HEADER_BEGIN);
+    if (openssh_header != NULL) {
+        key = ssh_pki_openssh_privkey_import(openssh_header,
                                              passphrase,
                                              auth_fn,
                                              auth_data);

tests/unittests/torture_pki_ed25519.c

@@ -149,6 +149,84 @@ static void torture_pki_ed25519_import_privkey_base64(void **state)
 
 }
 
+static void torture_pki_ed25519_import_privkey_base64_comment(void **state)
+{
+    int rc, file_str_len;
+    const char *comment_str = "#this is line-comment\n#this is another\n";
+    char *key_str = NULL, *file_str = NULL;
+    ssh_key key = NULL;
+    const char *passphrase = torture_get_testkey_passphrase();
+    enum ssh_keytypes_e type;
+
+    (void) state; /* unused */
+
+    key_str = torture_pki_read_file(LIBSSH_ED25519_TESTKEY);
+    assert_non_null(key_str);
+
+    file_str_len = strlen(comment_str) + strlen(key_str) + 1;
+    file_str = malloc(file_str_len);
+    assert_non_null(file_str);
+    rc = snprintf(file_str, file_str_len, "%s%s", comment_str, key_str);
+    assert_int_equal(rc, file_str_len - 1);
+
+    rc = ssh_pki_import_privkey_base64(file_str, passphrase, NULL, NULL, &key);
+    assert_true(rc == 0);
+    assert_non_null(key);
+
+    type = ssh_key_type(key);
+    assert_true(type == SSH_KEYTYPE_ED25519);
+
+    rc = ssh_key_is_private(key);
+    assert_true(rc == 1);
+
+    rc = ssh_key_is_public(key);
+    assert_true(rc == 1);
+
+    free(key_str);
+    free(file_str);
+    SSH_KEY_FREE(key);
+
+}
+
+static void torture_pki_ed25519_import_privkey_base64_whitespace(void **state)
+{
+    int rc, file_str_len;
+    const char *whitespace_str = "      \n\t\t\t\t\t\n\n\n\n\n";
+    char *key_str = NULL, *file_str = NULL;
+    ssh_key key = NULL;
+    const char *passphrase = torture_get_testkey_passphrase();
+    enum ssh_keytypes_e type;
+
+    (void) state; /* unused */
+
+    key_str = torture_pki_read_file(LIBSSH_ED25519_TESTKEY);
+    assert_non_null(key_str);
+
+    file_str_len = strlen(whitespace_str) + strlen(key_str) + 1;
+    file_str = malloc(file_str_len);
+    assert_non_null(file_str);
+    rc = snprintf(file_str, file_str_len, "%s%s", whitespace_str, key_str);
+    assert_int_equal(rc, file_str_len - 1);
+
+    rc = ssh_pki_import_privkey_base64(file_str, passphrase, NULL, NULL, &key);
+    assert_true(rc == 0);
+    assert_non_null(key);
+
+    type = ssh_key_type(key);
+    assert_true(type == SSH_KEYTYPE_ED25519);
+
+    rc = ssh_key_is_private(key);
+    assert_true(rc == 1);
+
+    rc = ssh_key_is_public(key);
+    assert_true(rc == 1);
+
+    free(key_str);
+    free(file_str);
+    SSH_KEY_FREE(key);
+
+}
+
 static void torture_pki_ed25519_import_export_privkey_base64(void **state)
 {
     char *b64_key = NULL;
@@ -730,6 +808,12 @@ int torture_run_tests(void) {
         cmocka_unit_test_setup_teardown(torture_pki_ed25519_import_privkey_base64,
                                         setup_ed25519_key,
                                         teardown),
+        cmocka_unit_test_setup_teardown(torture_pki_ed25519_import_privkey_base64_comment,
+                                        setup_ed25519_key,
+                                        teardown),
+        cmocka_unit_test_setup_teardown(torture_pki_ed25519_import_privkey_base64_whitespace,
+                                        setup_ed25519_key,
+                                        teardown),
         cmocka_unit_test_setup_teardown(torture_pki_ed25519_import_export_privkey_base64,
                                         setup_ed25519_key,
                                         teardown),