/*
* 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;
}