Add example SSH token handler.

Provides example of loadable token handler for activation
json validation and metadata dump.

For creating new ssh example token use special cryptsetup-ssh
binary.

tokens/ssh/cryptsetup-ssh.c

@@ -0,0 +1,122 @@
+/*
+ * Example of LUKS2 token storing third party metadata (EXAMPLE)
+ *
+ * Copyright (C) 2016-2020 Milan Broz <gmazyland@gmail.com>
+ *
+ * Use:
+ *  - generate ssh example token
+ *
+ * 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 "libcryptsetup.h"
+
+#define TOKEN_NAME "ssh"
+
+#define PASSWORD_LENGTH 8192
+
+#define l_err(cd, x...) crypt_logf(cd, CRYPT_LOG_ERROR, x)
+#define l_dbg(cd, x...) crypt_logf(cd, CRYPT_LOG_DEBUG, x)
+
+static int token_add(
+		const char *device,
+		const char *server,
+		const char *user,
+		const char *path,
+		const char *keypath)
+
+{
+	struct crypt_device *cd;
+	json_object *jobj = NULL;
+	json_object *jobj_keyslots = NULL;
+	const char *string_token;
+	int r, token;
+
+	r = crypt_init(&cd, device);
+	if (r)
+		return r;
+
+	r = crypt_load(cd, CRYPT_LUKS2, NULL);
+	if (r)
+		goto out;
+
+	r = -EINVAL;
+	jobj = json_object_new_object();
+	if (!jobj)
+		goto out;
+
+	/* type is mandatory field in all tokens and must match handler name member */
+	json_object_object_add(jobj, "type", json_object_new_string(TOKEN_NAME));
+
+	jobj_keyslots = json_object_new_array();
+
+	/* mandatory array field (may be empty and assigned later */
+	json_object_object_add(jobj, "keyslots", jobj_keyslots);
+
+	/* custom metadata */
+	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));
+	json_object_object_add(jobj, "ssh_keypath", json_object_new_string(keypath));
+
+	string_token = json_object_to_json_string_ext(jobj, JSON_C_TO_STRING_PLAIN);
+	if (!string_token) {
+		r = -EINVAL;
+		goto out;
+	}
+
+	l_dbg(cd, "Token JSON: %s", string_token);
+
+	r = crypt_token_json_set(cd, CRYPT_ANY_TOKEN, string_token);
+	if (r < 0) {
+		l_err(cd, "Failed to write ssh token json.");
+		goto out;
+	}
+
+	token = r;
+	r = crypt_token_assign_keyslot(cd, token, CRYPT_ANY_SLOT);
+	if (r != token) {
+		crypt_token_json_set(cd, token, NULL);
+		r = -EINVAL;
+	}
+out:
+	json_object_put(jobj);
+	crypt_free(cd);
+	return r;
+}
+
+static void token_help(void)
+{
+	printf("Use parameters:\n add device server user path keypath\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], argv[6]);
+
+	token_help();
+	return EXIT_FAILURE;
+}