1 files changed, 250 insertions, 0 deletions
diff --git a/docs/examples/crypt_luks_usage.c b/docs/examples/crypt_luks_usage.c
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+++ b/docs/examples/crypt_luks_usage.c
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+/*
+ *  libcryptsetup API - using LUKS device example
+ *
+ * Copyright (C) 2011-2021 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;
+	int r;
+
+	/*
+	 * The crypt_init() call is used  to initialize crypt_device context,
+	 * The path parameter specifies a device path.
+	 *
+	 * For path, you can use either link to a file or block device.
+	 * The loopback device 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 to the device.
+	 */
+	printf("Device %s will be formatted as a LUKS device after 5 seconds.\n"
+	       "Press CTRL+C now if you want to cancel this operation.\n", path);
+	sleep(5);
+
+	/*
+	 * NULLs for uuid and volume_key means that these attributes will be
+	 * generated during crypt_format().
+	 */
+	r = crypt_format(cd,		/* crypt context */
+			 CRYPT_LUKS2,	/* LUKS2 is a new LUKS format; use CRYPT_LUKS1 for LUKS1 */
+			 "aes",		/* used cipher */
+			 "xts-plain64",	/* used block mode and IV */
+			 NULL,		/* generate UUID */
+			 NULL,		/* generate volume key from RNG */
+			 512 / 8,	/* 512bit key - here AES-256 in XTS mode, size is in bytes */
+			 NULL);		/* default parameters */
+
+	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 a LUKS header, but there is no active keyslot.
+	 *
+	 * crypt_keyslot_add_* call stores the volume_key in the encrypted form into the keyslot.
+	 *
+	 * After format, the volume key is stored internally.
+	 */
+	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 authenticating with the first keyslot.
+	 * It decrypts the volume key from the first keyslot and creates a new one with the specified 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.
+	 */
+	r = crypt_init(&cd, path);
+	if (r < 0) {
+		printf("crypt_init() failed for %s.\n", path);
+		return r;
+	}
+
+	/*
+	 * crypt_load() is used to load existing LUKS header from a block device
+	 */
+	r = crypt_load(cd,		/* crypt context */
+		       CRYPT_LUKS,	/* requested type - here LUKS of any 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 a device-mapper device with the specified name.
+	 */
+	r = crypt_activate_by_passphrase(cd,		/* crypt context */
+					 device_name,	/* device name to activate */
+					 CRYPT_ANY_SLOT,/* the keyslot use (try all here) */
+					 "foo", 3,	/* passphrase */
+					 CRYPT_ACTIVATE_READONLY); /* flags */
+	if (r < 0) {
+		printf("Device %s activation failed.\n", device_name);
+		crypt_free(cd);
+		return r;
+	}
+
+	printf("%s device %s/%s is active.\n", crypt_get_type(cd), 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 the active device.
+	 */
+	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 context by an active device-mapper name
+	 */
+	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 a 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;
+}