/*

 * LUKS - Linux Unified Key Setup v2, LUKS2 header format code

 *

 * Copyright (C) 2015-2020 Red Hat, Inc. All rights reserved.

 * Copyright (C) 2015-2020 Milan Broz

 *

 * 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 "luks2_internal.h"

#include <uuid/uuid.h>

#include <assert.h>

struct area {

	uint64_t offset;

	uint64_t length;

};

static size_t get_area_size(size_t keylength)

{

	//FIXME: calculate this properly, for now it is AF_split_sectors

	return size_round_up(keylength * 4000, 4096);

}

static size_t get_min_offset(struct luks2_hdr *hdr)

{

	return 2 * hdr->hdr_size;

}

static size_t get_max_offset(struct luks2_hdr *hdr)

{

	return LUKS2_hdr_and_areas_size(hdr->jobj);

}

int LUKS2_find_area_max_gap(struct crypt_device *cd, struct luks2_hdr *hdr,

			uint64_t *area_offset, uint64_t *area_length)

{

	struct area areas[LUKS2_KEYSLOTS_MAX], sorted_areas[LUKS2_KEYSLOTS_MAX+1] = {};

	int i, j, k, area_i;

	size_t valid_offset, offset, length;

	/* fill area offset + length table */

	for (i = 0; i < LUKS2_KEYSLOTS_MAX; i++) {

		if (!LUKS2_keyslot_area(hdr, i, &areas[i].offset, &areas[i].length))

			continue;

		areas[i].length = 0;

		areas[i].offset = 0;

	}

	/* sort table */

	k = 0; /* index in sorted table */

	for (i = 0; i < LUKS2_KEYSLOTS_MAX; i++) {

		offset = get_max_offset(hdr) ?: UINT64_MAX;

		area_i = -1;

		/* search for the smallest offset in table */

		for (j = 0; j < LUKS2_KEYSLOTS_MAX; j++)

			if (areas[j].offset && areas[j].offset <= offset) {

				area_i = j;

				offset = areas[j].offset;

			}

		if (area_i >= 0) {

			sorted_areas[k].length = areas[area_i].length;

			sorted_areas[k].offset = areas[area_i].offset;

			areas[area_i].length = 0;

			areas[area_i].offset = 0;

			k++;

		}

	}

	sorted_areas[LUKS2_KEYSLOTS_MAX].offset = get_max_offset(hdr);

	sorted_areas[LUKS2_KEYSLOTS_MAX].length = 1;

	/* search for the gap we can use */

	length = valid_offset = 0;

	offset = get_min_offset(hdr);

	for (i = 0; i < LUKS2_KEYSLOTS_MAX+1; i++) {

		/* skip empty */

		if (sorted_areas[i].offset == 0 || sorted_areas[i].length == 0)

			continue;

		/* found bigger gap than the last one */

		if ((offset < sorted_areas[i].offset) && (sorted_areas[i].offset - offset) > length) {

			length = sorted_areas[i].offset - offset;

			valid_offset = offset;

		}

		/* move beyond allocated area */

		offset = sorted_areas[i].offset + sorted_areas[i].length;

	}

	/* this search 'algorithm' does not work with unaligned areas */

	assert(length == size_round_up(length, 4096));

	assert(valid_offset == size_round_up(valid_offset, 4096));

	if (!length) {

		log_dbg(cd, "Not enough space in header keyslot area.");

		return -EINVAL;

	}

	log_dbg(cd, "Found largest free area %zu -> %zu", valid_offset, length + valid_offset);

	*area_offset = valid_offset;

	*area_length = length;

	return 0;

}

int LUKS2_find_area_gap(struct crypt_device *cd, struct luks2_hdr *hdr,

			size_t keylength, uint64_t *area_offset, uint64_t *area_length)

{

	struct area areas[LUKS2_KEYSLOTS_MAX], sorted_areas[LUKS2_KEYSLOTS_MAX] = {};

	int i, j, k, area_i;

	size_t offset, length;

	/* fill area offset + length table */

	for (i = 0; i < LUKS2_KEYSLOTS_MAX; i++) {

		if (!LUKS2_keyslot_area(hdr, i, &areas[i].offset, &areas[i].length))

			continue;

		areas[i].length = 0;

		areas[i].offset = 0;

	}

	/* sort table */

	k = 0; /* index in sorted table */

	for (i = 0; i < LUKS2_KEYSLOTS_MAX; i++) {

		offset = get_max_offset(hdr) ?: UINT64_MAX;

		area_i = -1;

		/* search for the smallest offset in table */

		for (j = 0; j < LUKS2_KEYSLOTS_MAX; j++)

			if (areas[j].offset && areas[j].offset <= offset) {

				area_i = j;

				offset = areas[j].offset;

			}

		if (area_i >= 0) {

			sorted_areas[k].length = areas[area_i].length;

			sorted_areas[k].offset = areas[area_i].offset;

			areas[area_i].length = 0;

			areas[area_i].offset = 0;

			k++;

		}

	}

	/* search for the gap we can use */

	offset = get_min_offset(hdr);

	length = get_area_size(keylength);

	for (i = 0; i < LUKS2_KEYSLOTS_MAX; i++) {

		/* skip empty */

		if (sorted_areas[i].offset == 0 || sorted_areas[i].length == 0)

			continue;

		/* enough space before the used area */

		if ((offset < sorted_areas[i].offset) && ((offset + length) <= sorted_areas[i].offset))

			break;

		/* both offset and length are already aligned to 4096 bytes */

		offset = sorted_areas[i].offset + sorted_areas[i].length;

	}

	if ((offset + length) > get_max_offset(hdr)) {

		log_dbg(cd, "Not enough space in header keyslot area.");

		return -EINVAL;

	}

	log_dbg(cd, "Found area %zu -> %zu", offset, length + offset);

	*area_offset = offset;

	*area_length = length;

	return 0;

}

int LUKS2_check_metadata_area_size(uint64_t metadata_size)

{

	/* see LUKS2_HDR2_OFFSETS */

	return (metadata_size != 0x004000 &&

		metadata_size != 0x008000 && metadata_size != 0x010000 &&

		metadata_size != 0x020000 && metadata_size != 0x040000 &&

		metadata_size != 0x080000 && metadata_size != 0x100000 &&

		metadata_size != 0x200000 && metadata_size != 0x400000);

}

int LUKS2_check_keyslots_area_size(uint64_t keyslots_size)

{

	return (MISALIGNED_4K(keyslots_size) ||

		keyslots_size > LUKS2_MAX_KEYSLOTS_SIZE);

}

int LUKS2_generate_hdr(

	struct crypt_device *cd,

	struct luks2_hdr *hdr,

	const struct volume_key *vk,

	const char *cipherName,

	const char *cipherMode,

	const char *integrity,

	const char *uuid,

	unsigned int sector_size,  /* in bytes */

	uint64_t data_offset,      /* in bytes */

	uint64_t align_offset,     /* in bytes */

	uint64_t required_alignment,

	uint64_t metadata_size,

	uint64_t keyslots_size)

{

	struct json_object *jobj_segment, *jobj_integrity, *jobj_keyslots, *jobj_segments, *jobj_config;

	char cipher[128];

	uuid_t partitionUuid;

	int digest;

	uint64_t mdev_size;

	if (!metadata_size)

		metadata_size = LUKS2_HDR_16K_LEN;

	hdr->hdr_size = metadata_size;

	if (data_offset && data_offset < get_min_offset(hdr)) {

		log_err(cd, _("Requested data offset is too small."));

		return -EINVAL;

	}

	/* Increase keyslot size according to data offset */

	if (!keyslots_size && data_offset)

		keyslots_size = data_offset - get_min_offset(hdr);

	/* keyslots size has to be 4 KiB aligned */

	keyslots_size -= (keyslots_size % 4096);

	if (keyslots_size > LUKS2_MAX_KEYSLOTS_SIZE)

		keyslots_size = LUKS2_MAX_KEYSLOTS_SIZE;

	if (!keyslots_size) {

		assert(LUKS2_DEFAULT_HDR_SIZE > 2 * LUKS2_HDR_OFFSET_MAX);

		keyslots_size = LUKS2_DEFAULT_HDR_SIZE - get_min_offset(hdr);

		/* Decrease keyslots_size due to metadata device being too small */

		if (!device_size(crypt_metadata_device(cd), &mdev_size) &&

		    ((keyslots_size + get_min_offset(hdr)) > mdev_size) &&

		    device_fallocate(crypt_metadata_device(cd), keyslots_size + get_min_offset(hdr)))

			keyslots_size = mdev_size - get_min_offset(hdr);

	}

	/* Decrease keyslots_size if we have smaller data_offset */

	if (data_offset && (keyslots_size + get_min_offset(hdr)) > data_offset) {

		keyslots_size = data_offset - get_min_offset(hdr);

		log_dbg(cd, "Decreasing keyslot area size to %" PRIu64

			" bytes due to the requested data offset %"

			PRIu64 " bytes.", keyslots_size, data_offset);

	}

	/* Data offset has priority */

	if (!data_offset && required_alignment) {

		data_offset = size_round_up(get_min_offset(hdr) + keyslots_size,

					    (size_t)required_alignment);

		data_offset += align_offset;

	}

	log_dbg(cd, "Formatting LUKS2 with JSON metadata area %" PRIu64

		" bytes and keyslots area %" PRIu64 " bytes.",

		metadata_size - LUKS2_HDR_BIN_LEN, keyslots_size);

	if (keyslots_size < (LUKS2_HDR_OFFSET_MAX - 2*LUKS2_HDR_16K_LEN))

		log_std(cd, _("WARNING: keyslots area (%" PRIu64 " bytes) is very small,"

			" available LUKS2 keyslot count is very limited.\n"),

			keyslots_size);

	hdr->seqid = 1;

	hdr->version = 2;

	memset(hdr->label, 0, LUKS2_LABEL_L);

	strcpy(hdr->checksum_alg, "sha256");

	crypt_random_get(cd, (char*)hdr->salt1, LUKS2_SALT_L, CRYPT_RND_SALT);

	crypt_random_get(cd, (char*)hdr->salt2, LUKS2_SALT_L, CRYPT_RND_SALT);

	if (uuid && uuid_parse(uuid, partitionUuid) == -1) {

		log_err(cd, _("Wrong LUKS UUID format provided."));

		return -EINVAL;

	}

	if (!uuid)

		uuid_generate(partitionUuid);

	uuid_unparse(partitionUuid, hdr->uuid);

	if (*cipherMode != '\0')

		snprintf(cipher, sizeof(cipher), "%s-%s", cipherName, cipherMode);

	else

		snprintf(cipher, sizeof(cipher), "%s", cipherName);

	hdr->jobj = json_object_new_object();

	jobj_keyslots = json_object_new_object();

	json_object_object_add(hdr->jobj, "keyslots", jobj_keyslots);

	json_object_object_add(hdr->jobj, "tokens", json_object_new_object());

	jobj_segments = json_object_new_object();

	json_object_object_add(hdr->jobj, "segments", jobj_segments);

	json_object_object_add(hdr->jobj, "digests", json_object_new_object());

	jobj_config = json_object_new_object();

	json_object_object_add(hdr->jobj, "config", jobj_config);

	digest = LUKS2_digest_create(cd, "pbkdf2", hdr, vk);

	if (digest < 0)

		goto err;

	if (LUKS2_digest_segment_assign(cd, hdr, 0, digest, 1, 0) < 0)

		goto err;

	jobj_segment = json_segment_create_crypt(data_offset, 0, NULL, cipher, sector_size, 0);

	if (!jobj_segment)

		goto err;

	if (integrity) {

		jobj_integrity = json_object_new_object();

		json_object_object_add(jobj_integrity, "type", json_object_new_string(integrity));

		json_object_object_add(jobj_integrity, "journal_encryption", json_object_new_string("none"));

		json_object_object_add(jobj_integrity, "journal_integrity", json_object_new_string("none"));

		json_object_object_add(jobj_segment, "integrity", jobj_integrity);

	}

	json_object_object_add_by_uint(jobj_segments, 0, jobj_segment);

	json_object_object_add(jobj_config, "json_size", crypt_jobj_new_uint64(metadata_size - LUKS2_HDR_BIN_LEN));

	json_object_object_add(jobj_config, "keyslots_size", crypt_jobj_new_uint64(keyslots_size));

	JSON_DBG(cd, hdr->jobj, "Header JSON:");

	return 0;

err:

	json_object_put(hdr->jobj);

	hdr->jobj = NULL;

	return -EINVAL;

}

int LUKS2_wipe_header_areas(struct crypt_device *cd,

	struct luks2_hdr *hdr)

{

	int r;

	uint64_t offset, length;

	size_t wipe_block;

	/* Wipe complete header, keyslots and padding areas with zeroes. */

	offset = 0;

	length = LUKS2_get_data_offset(hdr) * SECTOR_SIZE;

	wipe_block = 1024 * 1024;

	if (LUKS2_hdr_validate(cd, hdr->jobj, hdr->hdr_size - LUKS2_HDR_BIN_LEN))

		return -EINVAL;

	/* On detached header wipe at least the first 4k */

	if (length == 0) {

		length = 4096;

		wipe_block = 4096;

	}

	log_dbg(cd, "Wiping LUKS areas (0x%06" PRIx64 " - 0x%06" PRIx64") with zeroes.",

		offset, length + offset);

	r = crypt_wipe_device(cd, crypt_metadata_device(cd), CRYPT_WIPE_ZERO,

			      offset, length, wipe_block, NULL, NULL);

	if (r < 0)

		return r;

	/* Wipe keyslot area */

	wipe_block = 1024 * 1024;

	offset = get_min_offset(hdr);

	length = LUKS2_keyslots_size(hdr->jobj);

	log_dbg(cd, "Wiping keyslots area (0x%06" PRIx64 " - 0x%06" PRIx64") with random data.",

		offset, length + offset);

	return crypt_wipe_device(cd, crypt_metadata_device(cd), CRYPT_WIPE_RANDOM,

				 offset, length, wipe_block, NULL, NULL);

}

/* FIXME: what if user wanted to keep original keyslots size? */

int LUKS2_set_keyslots_size(struct crypt_device *cd,

		struct luks2_hdr *hdr,

		uint64_t data_offset)

{

	json_object *jobj_config;

	uint64_t keyslots_size;

	if (data_offset < get_min_offset(hdr))

		return 1;

	keyslots_size = data_offset - get_min_offset(hdr);

	/* keep keyslots_size reasonable for custom data alignments */

	if (keyslots_size > LUKS2_MAX_KEYSLOTS_SIZE)

		keyslots_size = LUKS2_MAX_KEYSLOTS_SIZE;

	/* keyslots size has to be 4 KiB aligned */

	keyslots_size -= (keyslots_size % 4096);

	if (!json_object_object_get_ex(hdr->jobj, "config", &jobj_config))

		return 1;

	json_object_object_add(jobj_config, "keyslots_size", crypt_jobj_new_uint64(keyslots_size));

	return 0;

}