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+/*
+ * An example of using LUKS device through libcryptsetup API
+ *
+ * Copyright (C) 2011-2019 Red Hat, Inc. All rights reserved.
+ *
+ * This file is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This file 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this file; 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 <unistd.h>
+#include <inttypes.h>
+#include <sys/types.h>
+#include <libcryptsetup.h>
+
+static int format_and_add_keyslots(const char *path)
+{
+ struct crypt_device *cd;
+ struct crypt_params_luks1 params;
+ int r;
+
+ /*
+ * crypt_init() call precedes most of operations of cryptsetup API. The call is used
+ * to initialize crypt device context stored in structure referenced by _cd_ in
+ * the example. Second parameter is used to pass underlaying device path.
+ *
+ * Note:
+ * If path refers to a regular file it'll be attached to a first free loop device.
+ * crypt_init() operation fails in case there's no more loop device available.
+ * Also, loop device will have the AUTOCLEAR flag set, so the file loopback will
+ * be detached automatically.
+ */
+
+ r = crypt_init(&cd, path);
+ if (r < 0 ) {
+ printf("crypt_init() failed for %s.\n", path);
+ return r;
+ }
+
+ printf("Context is attached to block device %s.\n", crypt_get_device_name(cd));
+
+ /*
+ * So far no data were written on your device. This will change with call of
+ * crypt_format() only if you specify CRYPT_LUKS1 as device type.
+ */
+ printf("Device %s will be formatted to LUKS device after 5 seconds.\n"
+ "Press CTRL+C now if you want to cancel this operation.\n", path);
+ sleep(5);
+
+
+ /*
+ * Prepare LUKS format parameters
+ *
+ * hash parameter defines PBKDF2 hash algorithm used in LUKS header.
+ * For compatibility reason we use SHA1 here.
+ */
+ params.hash = "sha1";
+
+ /*
+ * data_alignment parameter is relevant only in case of the luks header
+ * and the payload are both stored on same device.
+ *
+ * if you set data_alignment = 0, cryptsetup will autodetect
+ * data_alignment according to underlaying device topology.
+ */
+ params.data_alignment = 0;
+
+ /*
+ * data_device parameter defines that no external device
+ * for luks header will be used
+ */
+ params.data_device = NULL;
+
+ /*
+ * NULLs for uuid and volume_key means that these attributes will be
+ * generated during crypt_format(). Volume key is generated with respect
+ * to key size parameter passed to function.
+ *
+ * crypt_format() checks device size (LUKS header must fit there).
+ */
+ r = crypt_format(cd, /* crypt context */
+ CRYPT_LUKS1, /* LUKS1 is standard LUKS header */
+ "aes", /* used cipher */
+ "xts-plain64", /* used block mode and IV generator*/
+ NULL, /* generate UUID */
+ NULL, /* generate volume key from RNG */
+ 256 / 8, /* 256bit key - here AES-128 in XTS mode, size is in bytes */
+ &params); /* parameters above */
+
+ if(r < 0) {
+ printf("crypt_format() failed on device %s\n", crypt_get_device_name(cd));
+ crypt_free(cd);
+ return r;
+ }
+
+ /*
+ * The device now contains LUKS1 header, but there is
+ * no active keyslot with encrypted volume key yet.
+ */
+
+ /*
+ * cryptt_kesylot_add_* call stores volume_key in encrypted form into keyslot.
+ * Without keyslot you can't manipulate with LUKS device after the context will be freed.
+ *
+ * To create a new keyslot you need to supply the existing one (to get the volume key from) or
+ * you need to supply the volume key.
+ *
+ * After format, we have volume key stored internally in context so add new keyslot
+ * using this internal volume key.
+ */
+ r = crypt_keyslot_add_by_volume_key(cd, /* crypt context */
+ CRYPT_ANY_SLOT, /* just use first free slot */
+ NULL, /* use internal volume key */
+ 0, /* unused (size of volume key) */
+ "foo", /* passphrase - NULL means query*/
+ 3); /* size of passphrase */
+
+ if (r < 0) {
+ printf("Adding keyslot failed.\n");
+ crypt_free(cd);
+ return r;
+ }
+
+ printf("The first keyslot is initialized.\n");
+
+ /*
+ * Add another keyslot, now using the first keyslot.
+ * It will decrypt volume key from the first keyslot and creates new one with another passphrase.
+ */
+ r = crypt_keyslot_add_by_passphrase(cd, /* crypt context */
+ CRYPT_ANY_SLOT, /* just use first free slot */
+ "foo", 3, /* passphrase for the old keyslot */
+ "bar", 3); /* passphrase for the new kesylot */
+ if (r < 0) {
+ printf("Adding keyslot failed.\n");
+ crypt_free(cd);
+ return r;
+ }
+
+ printf("The second keyslot is initialized.\n");
+
+ crypt_free(cd);
+ return 0;
+}
+
+static int activate_and_check_status(const char *path, const char *device_name)
+{
+ struct crypt_device *cd;
+ struct crypt_active_device cad;
+ int r;
+
+ /*
+ * LUKS device activation example.
+ * It's sequence of sub-steps: device initialization, LUKS header load
+ * and the device activation itself.
+ */
+ r = crypt_init(&cd, path);
+ if (r < 0 ) {
+ printf("crypt_init() failed for %s.\n", path);
+ return r;
+ }
+
+ /*
+ * crypt_load() is used to load the LUKS header from block device
+ * into crypt_device context.
+ */
+ r = crypt_load(cd, /* crypt context */
+ CRYPT_LUKS1, /* requested type */
+ NULL); /* additional parameters (not used) */
+
+ if (r < 0) {
+ printf("crypt_load() failed on device %s.\n", crypt_get_device_name(cd));
+ crypt_free(cd);
+ return r;
+ }
+
+ /*
+ * Device activation creates device-mapper devie mapping with name device_name.
+ */
+ r = crypt_activate_by_passphrase(cd, /* crypt context */
+ device_name, /* device name to activate */
+ CRYPT_ANY_SLOT,/* which slot use (ANY - try all) */
+ "foo", 3, /* passphrase */
+ CRYPT_ACTIVATE_READONLY); /* flags */
+ if (r < 0) {
+ printf("Device %s activation failed.\n", device_name);
+ crypt_free(cd);
+ return r;
+ }
+
+ printf("LUKS device %s/%s is active.\n", crypt_get_dir(), device_name);
+ printf("\tcipher used: %s\n", crypt_get_cipher(cd));
+ printf("\tcipher mode: %s\n", crypt_get_cipher_mode(cd));
+ printf("\tdevice UUID: %s\n", crypt_get_uuid(cd));
+
+ /*
+ * Get info about active device (query DM backend)
+ */
+ r = crypt_get_active_device(cd, device_name, &cad);
+ if (r < 0) {
+ printf("Get info about active device %s failed.\n", device_name);
+ crypt_deactivate(cd, device_name);
+ crypt_free(cd);
+ return r;
+ }
+
+ printf("Active device parameters for %s:\n"
+ "\tDevice offset (in sectors): %" PRIu64 "\n"
+ "\tIV offset (in sectors) : %" PRIu64 "\n"
+ "\tdevice size (in sectors) : %" PRIu64 "\n"
+ "\tread-only flag : %s\n",
+ device_name, cad.offset, cad.iv_offset, cad.size,
+ cad.flags & CRYPT_ACTIVATE_READONLY ? "1" : "0");
+
+ crypt_free(cd);
+ return 0;
+}
+
+static int handle_active_device(const char *device_name)
+{
+ struct crypt_device *cd;
+ int r;
+
+ /*
+ * crypt_init_by_name() initializes device context and loads LUKS header from backing device
+ */
+ r = crypt_init_by_name(&cd, device_name);
+ if (r < 0) {
+ printf("crypt_init_by_name() failed for %s.\n", device_name);
+ return r;
+ }
+
+ if (crypt_status(cd, device_name) == CRYPT_ACTIVE)
+ printf("Device %s is still active.\n", device_name);
+ else {
+ printf("Something failed perhaps, device %s is not active.\n", device_name);
+ crypt_free(cd);
+ return -1;
+ }
+
+ /*
+ * crypt_deactivate() is used to deactivate device
+ */
+ r = crypt_deactivate(cd, device_name);
+ if (r < 0) {
+ printf("crypt_deactivate() failed.\n");
+ crypt_free(cd);
+ return r;
+ }
+
+ printf("Device %s is now deactivated.\n", device_name);
+
+ crypt_free(cd);
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ if (geteuid()) {
+ printf("Using of libcryptsetup requires super user privileges.\n");
+ return 1;
+ }
+
+ if (argc != 2) {
+ printf("usage: ./crypt_luks_usage <path>\n"
+ "<path> refers to either a regular file or a block device.\n"
+ " WARNING: the file or device will be wiped.\n");
+ return 2;
+ }
+
+ if (format_and_add_keyslots(argv[1]))
+ return 3;
+
+ if (activate_and_check_status(argv[1], "example_device"))
+ return 4;
+
+ if (handle_active_device("example_device"))
+ return 5;
+
+ return 0;
+}