1 files changed, 264 insertions, 0 deletions
diff --git a/misc/luks2_keyslot_example/keyslot_test_remote_pass.c b/misc/luks2_keyslot_example/keyslot_test_remote_pass.c
new file mode 100644
index 0000000..5aa9500
--- /dev/null
+++ b/misc/luks2_keyslot_example/keyslot_test_remote_pass.c
@@ -0,0 +1,264 @@
+/*
+ * Example of LUKS2 token storing third party metadata (EXAMPLE)
+ *
+ * Copyright (C) 2016-2021 Milan Broz <gmazyland@gmail.com>
+ *
+ * Use:
+ *  - generate LUKS device
+ *  - store passphrase used in previous step remotely (single line w/o \n\r)
+ *  - add new token using this example
+ *  - activate device with passphrase recovered remotely using the example
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <json-c/json.h>
+#include <libssh/libssh.h>
+#include <libssh/sftp.h>
+#include "libcryptsetup.h"
+
+#define TOKEN_NUM 0
+#define TOKEN_TYPE "sshkeytest"
+
+#define PASSWORD_LENGTH 8192
+
+static json_object *get_token_jobj(struct crypt_device *cd, int token)
+{
+	const char *json_slot;
+
+	if (crypt_token_json_get(cd, token, &json_slot))
+		return NULL;
+
+	return json_tokener_parse(json_slot);
+}
+
+static int read_remote_passphrase(struct crypt_device *cd, const char *host,
+			   const char *user, const char *path,
+			   char *password, size_t password_size)
+{
+	ssh_session ssh = NULL;
+	sftp_session sftp = NULL;
+	sftp_file file = NULL;
+	ssh_key pkey = NULL;
+
+	int r, port = 22;
+
+	ssh = ssh_new();
+	if (!ssh)
+		return -EINVAL;
+
+	ssh_options_set(ssh, SSH_OPTIONS_HOST, host);
+	ssh_options_set(ssh, SSH_OPTIONS_USER, user);
+	ssh_options_set(ssh, SSH_OPTIONS_PORT, &port);
+
+	r = ssh_connect(ssh);
+	if (r != SSH_OK) {
+		crypt_log(cd, CRYPT_LOG_ERROR, "Connection failed: ");
+		goto out;
+	}
+
+	r = ssh_is_server_known(ssh);
+	if (r != SSH_SERVER_KNOWN_OK) {
+		crypt_log(cd, CRYPT_LOG_ERROR, "Server not known: ");
+		r = SSH_AUTH_ERROR;
+		goto out;
+	}
+
+	r = ssh_pki_import_privkey_file("/home/user/.ssh/id_rsa", NULL, NULL, NULL, &pkey);
+	if (r != SSH_OK) {
+		crypt_log(cd, CRYPT_LOG_ERROR, "error\n");
+		r = SSH_AUTH_ERROR;
+		goto out;
+	}
+
+	r = ssh_userauth_publickey(ssh, user, pkey);
+	/* or r = ssh_userauth_publickey_auto(ssh, user, NULL); */
+	if (r != SSH_AUTH_SUCCESS) {
+		crypt_log(cd, CRYPT_LOG_ERROR, "Public key authentication error: ");
+		goto out;
+	}
+
+	sftp = sftp_new(ssh);
+	if (!sftp) {
+		crypt_log(cd, CRYPT_LOG_ERROR, "Cannot create sftp session: ");
+		r = SSH_FX_FAILURE;
+		goto out;
+	}
+
+	r = sftp_init(sftp);
+	if (r != SSH_OK) {
+		crypt_log(cd, CRYPT_LOG_ERROR, "Cannot init sftp session: ");
+		goto out;
+	}
+
+	file = sftp_open(sftp, path, O_RDONLY, 0);
+	if (!file) {
+		crypt_log(cd, CRYPT_LOG_ERROR, "Cannot create sftp session: ");
+		r = SSH_FX_FAILURE;
+		goto out;
+	}
+
+	r = sftp_read(file, password, password_size);
+	if (r < 1 || (size_t)r >= password_size) {
+		crypt_log(cd, CRYPT_LOG_ERROR, "Cannot read remote password: ");
+		r = SSH_FX_FAILURE;
+		goto out;
+	}
+
+	r = SSH_OK;
+out:
+	if (r != SSH_OK) {
+		crypt_log(cd, CRYPT_LOG_ERROR, ssh_get_error(ssh));
+		crypt_log(cd, CRYPT_LOG_ERROR, "\n");
+	}
+
+	if (pkey)
+		ssh_key_free(pkey);
+
+	if (file)
+		sftp_close(file);
+	if (sftp)
+		sftp_free(sftp);
+	ssh_disconnect(ssh);
+	ssh_free(ssh);
+	return r == SSH_OK ? 0 : -EINVAL;
+}
+
+static int token_add(const char *device, const char *server,
+		   const char *user, const char *path)
+{
+	struct crypt_device *cd = NULL;
+	json_object *jobj = NULL, *jobj_keyslots;
+	int r;
+
+	r = crypt_init(&cd, device);
+	if (r < 0)
+		return EXIT_FAILURE;
+
+	r = crypt_load(cd, CRYPT_LUKS2, NULL);
+	if (r < 0) {
+		crypt_free(cd);
+		return EXIT_FAILURE;
+	}
+
+	jobj = json_object_new_object();
+
+	/* 'type' is mandatory field */
+	json_object_object_add(jobj, "type", json_object_new_string(TOKEN_TYPE));
+
+	/* 'keyslots' is mandatory field (may be empty) */
+	jobj_keyslots = json_object_new_array();
+	json_object_array_add(jobj_keyslots, json_object_new_string("0"));
+	json_object_array_add(jobj_keyslots, json_object_new_string("1"));
+	json_object_object_add(jobj, "keyslots", jobj_keyslots);
+
+	/* third party values */
+	json_object_object_add(jobj, "ssh_server", json_object_new_string(server));
+	json_object_object_add(jobj, "ssh_user", json_object_new_string(user));
+	json_object_object_add(jobj, "ssh_path", json_object_new_string(path));
+
+	r = crypt_token_json_set(cd, TOKEN_NUM, json_object_to_json_string_ext(jobj, JSON_C_TO_STRING_PLAIN));
+
+	crypt_free(cd);
+	json_object_put(jobj);
+
+	return EXIT_SUCCESS;
+}
+
+static int download_remote_password(struct crypt_device *cd, char *password, size_t password_len)
+{
+	json_object *jobj_server, *jobj_user, *jobj_path, *jobj_keyslot;
+
+	/* get token json object representation as string */
+	jobj_keyslot = get_token_jobj(cd, TOKEN_NUM);
+	if (!jobj_keyslot)
+		return -EINVAL;
+
+
+	/* extract third party metadata necessary to extract passphrase remotely */
+	json_object_object_get_ex(jobj_keyslot, "ssh_server", &jobj_server);
+	json_object_object_get_ex(jobj_keyslot, "ssh_user",   &jobj_user);
+	json_object_object_get_ex(jobj_keyslot, "ssh_path",   &jobj_path);
+
+	return read_remote_passphrase(cd, json_object_get_string(jobj_server),
+				    json_object_get_string(jobj_user),
+				    json_object_get_string(jobj_path),
+				    password, password_len);
+}
+
+static int open_by_remote_password(const char *device, const char *name)
+{
+	char password[PASSWORD_LENGTH+1];
+	struct crypt_device *cd = NULL;
+	int r;
+
+	r = crypt_init(&cd, device);
+	if (r < 0)
+		return EXIT_FAILURE;
+
+	r = crypt_load(cd, CRYPT_LUKS2, NULL);
+	if (r < 0) {
+		crypt_free(cd);
+		return EXIT_FAILURE;
+	}
+
+	/* custom routines to acquire password */
+	r = download_remote_password(cd, password, sizeof(password));
+	if (r < 0) {
+		crypt_free(cd);
+		return EXIT_FAILURE;
+	}
+
+	password[PASSWORD_LENGTH] = '\0';
+
+	/* open first genuine LUKS2 keyslot available provided the password matches */
+	/* for the sake of simplicity password is a string */
+	r = crypt_activate_by_passphrase(cd, name, CRYPT_ANY_SLOT, password, strlen(password), 0);
+
+	crypt_free(cd);
+	return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+static void keyslot_help(void)
+{
+	printf("Use parameters:\n add device server user path\n"
+		" open device name\n");
+	exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+	crypt_set_debug_level(CRYPT_LOG_DEBUG);
+
+	/* Adding slot to device */
+	if (argc == 6 && !strcmp("add", argv[1]))
+		return token_add(argv[2], argv[3], argv[4], argv[5]);
+
+	/* Password check without activation */
+	if (argc == 3 && !strcmp("open", argv[1]))
+		return open_by_remote_password(argv[2], NULL);
+
+	/* Password check with activation (requires root) */
+	if (argc == 4 && !strcmp("open", argv[1]))
+		return open_by_remote_password(argv[2], argv[3]);
+
+	keyslot_help();
+	return 1;
+}