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qemu-e2k/crypto/block-luks.c
Maxim Levitsky 557d2bdcca qcrypto/luks: implement encryption key management 
Next few patches will expose that functionality to the user.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200608094030.670121-3-mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-07-06 08:49:28 +02:00

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/*
* QEMU Crypto block device encryption LUKS format
*
* Copyright (c) 2015-2016 Red Hat, Inc.
*
* This library 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 library 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 library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/bswap.h"
#include "block-luks.h"
#include "crypto/hash.h"
#include "crypto/afsplit.h"
#include "crypto/pbkdf.h"
#include "crypto/secret.h"
#include "crypto/random.h"
#include "qemu/uuid.h"
#include "qemu/coroutine.h"
#include "qemu/bitmap.h"
/*
* Reference for the LUKS format implemented here is
*
* docs/on-disk-format.pdf
*
* in 'cryptsetup' package source code
*
* This file implements the 1.2.1 specification, dated
* Oct 16, 2011.
*/
typedef struct QCryptoBlockLUKS QCryptoBlockLUKS;
typedef struct QCryptoBlockLUKSHeader QCryptoBlockLUKSHeader;
typedef struct QCryptoBlockLUKSKeySlot QCryptoBlockLUKSKeySlot;
/* The following constants are all defined by the LUKS spec */
#define QCRYPTO_BLOCK_LUKS_VERSION 1
#define QCRYPTO_BLOCK_LUKS_MAGIC_LEN 6
#define QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN 32
#define QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN 32
#define QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN 32
#define QCRYPTO_BLOCK_LUKS_DIGEST_LEN 20
#define QCRYPTO_BLOCK_LUKS_SALT_LEN 32
#define QCRYPTO_BLOCK_LUKS_UUID_LEN 40
#define QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS 8
#define QCRYPTO_BLOCK_LUKS_STRIPES 4000
#define QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS 1000
#define QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS 1000
#define QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET 4096
#define QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED 0x0000DEAD
#define QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED 0x00AC71F3
#define QCRYPTO_BLOCK_LUKS_SECTOR_SIZE 512LL
#define QCRYPTO_BLOCK_LUKS_DEFAULT_ITER_TIME_MS 2000
#define QCRYPTO_BLOCK_LUKS_ERASE_ITERATIONS 40
static const char qcrypto_block_luks_magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN] = {
'L', 'U', 'K', 'S', 0xBA, 0xBE
};
typedef struct QCryptoBlockLUKSNameMap QCryptoBlockLUKSNameMap;
struct QCryptoBlockLUKSNameMap {
const char *name;
int id;
};
typedef struct QCryptoBlockLUKSCipherSizeMap QCryptoBlockLUKSCipherSizeMap;
struct QCryptoBlockLUKSCipherSizeMap {
uint32_t key_bytes;
int id;
};
typedef struct QCryptoBlockLUKSCipherNameMap QCryptoBlockLUKSCipherNameMap;
struct QCryptoBlockLUKSCipherNameMap {
const char *name;
const QCryptoBlockLUKSCipherSizeMap *sizes;
};
static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_aes[] = {
{ 16, QCRYPTO_CIPHER_ALG_AES_128 },
{ 24, QCRYPTO_CIPHER_ALG_AES_192 },
{ 32, QCRYPTO_CIPHER_ALG_AES_256 },
{ 0, 0 },
};
static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_cast5[] = {
{ 16, QCRYPTO_CIPHER_ALG_CAST5_128 },
{ 0, 0 },
};
static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_serpent[] = {
{ 16, QCRYPTO_CIPHER_ALG_SERPENT_128 },
{ 24, QCRYPTO_CIPHER_ALG_SERPENT_192 },
{ 32, QCRYPTO_CIPHER_ALG_SERPENT_256 },
{ 0, 0 },
};
static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_twofish[] = {
{ 16, QCRYPTO_CIPHER_ALG_TWOFISH_128 },
{ 24, QCRYPTO_CIPHER_ALG_TWOFISH_192 },
{ 32, QCRYPTO_CIPHER_ALG_TWOFISH_256 },
{ 0, 0 },
};
static const QCryptoBlockLUKSCipherNameMap
qcrypto_block_luks_cipher_name_map[] = {
{ "aes", qcrypto_block_luks_cipher_size_map_aes },
{ "cast5", qcrypto_block_luks_cipher_size_map_cast5 },
{ "serpent", qcrypto_block_luks_cipher_size_map_serpent },
{ "twofish", qcrypto_block_luks_cipher_size_map_twofish },
};
/*
* This struct is written to disk in big-endian format,
* but operated upon in native-endian format.
*/
struct QCryptoBlockLUKSKeySlot {
/* state of keyslot, enabled/disable */
uint32_t active;
/* iterations for PBKDF2 */
uint32_t iterations;
/* salt for PBKDF2 */
uint8_t salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
/* start sector of key material */
uint32_t key_offset_sector;
/* number of anti-forensic stripes */
uint32_t stripes;
};
QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSKeySlot) != 48);
/*
* This struct is written to disk in big-endian format,
* but operated upon in native-endian format.
*/
struct QCryptoBlockLUKSHeader {
/* 'L', 'U', 'K', 'S', '0xBA', '0xBE' */
char magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN];
/* LUKS version, currently 1 */
uint16_t version;
/* cipher name specification (aes, etc) */
char cipher_name[QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN];
/* cipher mode specification (cbc-plain, xts-essiv:sha256, etc) */
char cipher_mode[QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN];
/* hash specification (sha256, etc) */
char hash_spec[QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN];
/* start offset of the volume data (in 512 byte sectors) */
uint32_t payload_offset_sector;
/* Number of key bytes */
uint32_t master_key_len;
/* master key checksum after PBKDF2 */
uint8_t master_key_digest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
/* salt for master key PBKDF2 */
uint8_t master_key_salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
/* iterations for master key PBKDF2 */
uint32_t master_key_iterations;
/* UUID of the partition in standard ASCII representation */
uint8_t uuid[QCRYPTO_BLOCK_LUKS_UUID_LEN];
/* key slots */
QCryptoBlockLUKSKeySlot key_slots[QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS];
};
QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592);
struct QCryptoBlockLUKS {
QCryptoBlockLUKSHeader header;
/* Main encryption algorithm used for encryption*/
QCryptoCipherAlgorithm cipher_alg;
/* Mode of encryption for the selected encryption algorithm */
QCryptoCipherMode cipher_mode;
/* Initialization vector generation algorithm */
QCryptoIVGenAlgorithm ivgen_alg;
/* Hash algorithm used for IV generation*/
QCryptoHashAlgorithm ivgen_hash_alg;
/*
* Encryption algorithm used for IV generation.
* Usually the same as main encryption algorithm
*/
QCryptoCipherAlgorithm ivgen_cipher_alg;
/* Hash algorithm used in pbkdf2 function */
QCryptoHashAlgorithm hash_alg;
/* Name of the secret that was used to open the image */
char *secret;
};
static int qcrypto_block_luks_cipher_name_lookup(const char *name,
QCryptoCipherMode mode,
uint32_t key_bytes,
Error **errp)
{
const QCryptoBlockLUKSCipherNameMap *map =
qcrypto_block_luks_cipher_name_map;
size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
size_t i, j;
if (mode == QCRYPTO_CIPHER_MODE_XTS) {
key_bytes /= 2;
}
for (i = 0; i < maplen; i++) {
if (!g_str_equal(map[i].name, name)) {
continue;
}
for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
if (map[i].sizes[j].key_bytes == key_bytes) {
return map[i].sizes[j].id;
}
}
}
error_setg(errp, "Algorithm %s with key size %d bytes not supported",
name, key_bytes);
return 0;
}
static const char *
qcrypto_block_luks_cipher_alg_lookup(QCryptoCipherAlgorithm alg,
Error **errp)
{
const QCryptoBlockLUKSCipherNameMap *map =
qcrypto_block_luks_cipher_name_map;
size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
size_t i, j;
for (i = 0; i < maplen; i++) {
for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
if (map[i].sizes[j].id == alg) {
return map[i].name;
}
}
}
error_setg(errp, "Algorithm '%s' not supported",
QCryptoCipherAlgorithm_str(alg));
return NULL;
}
/* XXX replace with qapi_enum_parse() in future, when we can
* make that function emit a more friendly error message */
static int qcrypto_block_luks_name_lookup(const char *name,
const QEnumLookup *map,
const char *type,
Error **errp)
{
int ret = qapi_enum_parse(map, name, -1, NULL);
if (ret < 0) {
error_setg(errp, "%s %s not supported", type, name);
return 0;
}
return ret;
}
#define qcrypto_block_luks_cipher_mode_lookup(name, errp) \
qcrypto_block_luks_name_lookup(name, \
&QCryptoCipherMode_lookup, \
"Cipher mode", \
errp)
#define qcrypto_block_luks_hash_name_lookup(name, errp) \
qcrypto_block_luks_name_lookup(name, \
&QCryptoHashAlgorithm_lookup, \
"Hash algorithm", \
errp)
#define qcrypto_block_luks_ivgen_name_lookup(name, errp) \
qcrypto_block_luks_name_lookup(name, \
&QCryptoIVGenAlgorithm_lookup, \
"IV generator", \
errp)
static bool
qcrypto_block_luks_has_format(const uint8_t *buf,
size_t buf_size)
{
const QCryptoBlockLUKSHeader *luks_header = (const void *)buf;
if (buf_size >= offsetof(QCryptoBlockLUKSHeader, cipher_name) &&
memcmp(luks_header->magic, qcrypto_block_luks_magic,
QCRYPTO_BLOCK_LUKS_MAGIC_LEN) == 0 &&
be16_to_cpu(luks_header->version) == QCRYPTO_BLOCK_LUKS_VERSION) {
return true;
} else {
return false;
}
}
/**
* Deal with a quirk of dm-crypt usage of ESSIV.
*
* When calculating ESSIV IVs, the cipher length used by ESSIV
* may be different from the cipher length used for the block
* encryption, becauses dm-crypt uses the hash digest length
* as the key size. ie, if you have AES 128 as the block cipher
* and SHA 256 as ESSIV hash, then ESSIV will use AES 256 as
* the cipher since that gets a key length matching the digest
* size, not AES 128 with truncated digest as might be imagined
*/
static QCryptoCipherAlgorithm
qcrypto_block_luks_essiv_cipher(QCryptoCipherAlgorithm cipher,
QCryptoHashAlgorithm hash,
Error **errp)
{
size_t digestlen = qcrypto_hash_digest_len(hash);
size_t keylen = qcrypto_cipher_get_key_len(cipher);
if (digestlen == keylen) {
return cipher;
}
switch (cipher) {
case QCRYPTO_CIPHER_ALG_AES_128:
case QCRYPTO_CIPHER_ALG_AES_192:
case QCRYPTO_CIPHER_ALG_AES_256:
if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_AES_128)) {
return QCRYPTO_CIPHER_ALG_AES_128;
} else if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_AES_192)) {
return QCRYPTO_CIPHER_ALG_AES_192;
} else if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_AES_256)) {
return QCRYPTO_CIPHER_ALG_AES_256;
} else {
error_setg(errp, "No AES cipher with key size %zu available",
digestlen);
return 0;
}
break;
case QCRYPTO_CIPHER_ALG_SERPENT_128:
case QCRYPTO_CIPHER_ALG_SERPENT_192:
case QCRYPTO_CIPHER_ALG_SERPENT_256:
if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_SERPENT_128)) {
return QCRYPTO_CIPHER_ALG_SERPENT_128;
} else if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_SERPENT_192)) {
return QCRYPTO_CIPHER_ALG_SERPENT_192;
} else if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_SERPENT_256)) {
return QCRYPTO_CIPHER_ALG_SERPENT_256;
} else {
error_setg(errp, "No Serpent cipher with key size %zu available",
digestlen);
return 0;
}
break;
case QCRYPTO_CIPHER_ALG_TWOFISH_128:
case QCRYPTO_CIPHER_ALG_TWOFISH_192:
case QCRYPTO_CIPHER_ALG_TWOFISH_256:
if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_TWOFISH_128)) {
return QCRYPTO_CIPHER_ALG_TWOFISH_128;
} else if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_TWOFISH_192)) {
return QCRYPTO_CIPHER_ALG_TWOFISH_192;
} else if (digestlen == qcrypto_cipher_get_key_len(
QCRYPTO_CIPHER_ALG_TWOFISH_256)) {
return QCRYPTO_CIPHER_ALG_TWOFISH_256;
} else {
error_setg(errp, "No Twofish cipher with key size %zu available",
digestlen);
return 0;
}
break;
default:
error_setg(errp, "Cipher %s not supported with essiv",
QCryptoCipherAlgorithm_str(cipher));
return 0;
}
}
/*
* Returns number of sectors needed to store the key material
* given number of anti forensic stripes
*/
static int
qcrypto_block_luks_splitkeylen_sectors(const QCryptoBlockLUKS *luks,
unsigned int header_sectors,
unsigned int stripes)
{
/*
* This calculation doesn't match that shown in the spec,
* but instead follows the cryptsetup implementation.
*/
size_t splitkeylen = luks->header.master_key_len * stripes;
/* First align the key material size to block size*/
size_t splitkeylen_sectors =
DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE);
/* Then also align the key material size to the size of the header */
return ROUND_UP(splitkeylen_sectors, header_sectors);
}
/*
* Stores the main LUKS header, taking care of endianess
*/
static int
qcrypto_block_luks_store_header(QCryptoBlock *block,
QCryptoBlockWriteFunc writefunc,
void *opaque,
Error **errp)
{
const QCryptoBlockLUKS *luks = block->opaque;
Error *local_err = NULL;
size_t i;
g_autofree QCryptoBlockLUKSHeader *hdr_copy = NULL;
/* Create a copy of the header */
hdr_copy = g_new0(QCryptoBlockLUKSHeader, 1);
memcpy(hdr_copy, &luks->header, sizeof(QCryptoBlockLUKSHeader));
/*
* Everything on disk uses Big Endian (tm), so flip header fields
* before writing them
*/
cpu_to_be16s(&hdr_copy->version);
cpu_to_be32s(&hdr_copy->payload_offset_sector);
cpu_to_be32s(&hdr_copy->master_key_len);
cpu_to_be32s(&hdr_copy->master_key_iterations);
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
cpu_to_be32s(&hdr_copy->key_slots[i].active);
cpu_to_be32s(&hdr_copy->key_slots[i].iterations);
cpu_to_be32s(&hdr_copy->key_slots[i].key_offset_sector);
cpu_to_be32s(&hdr_copy->key_slots[i].stripes);
}
/* Write out the partition header and key slot headers */
writefunc(block, 0, (const uint8_t *)hdr_copy, sizeof(*hdr_copy),
opaque, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
return 0;
}
/*
* Loads the main LUKS header,and byteswaps it to native endianess
* And run basic sanity checks on it
*/
static int
qcrypto_block_luks_load_header(QCryptoBlock *block,
QCryptoBlockReadFunc readfunc,
void *opaque,
Error **errp)
{
ssize_t rv;
size_t i;
QCryptoBlockLUKS *luks = block->opaque;
/*
* Read the entire LUKS header, minus the key material from
* the underlying device
*/
rv = readfunc(block, 0,
(uint8_t *)&luks->header,
sizeof(luks->header),
opaque,
errp);
if (rv < 0) {
return rv;
}
/*
* The header is always stored in big-endian format, so
* convert everything to native
*/
be16_to_cpus(&luks->header.version);
be32_to_cpus(&luks->header.payload_offset_sector);
be32_to_cpus(&luks->header.master_key_len);
be32_to_cpus(&luks->header.master_key_iterations);
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
be32_to_cpus(&luks->header.key_slots[i].active);
be32_to_cpus(&luks->header.key_slots[i].iterations);
be32_to_cpus(&luks->header.key_slots[i].key_offset_sector);
be32_to_cpus(&luks->header.key_slots[i].stripes);
}
return 0;
}
/*
* Does basic sanity checks on the LUKS header
*/
static int
qcrypto_block_luks_check_header(const QCryptoBlockLUKS *luks, Error **errp)
{
size_t i, j;
unsigned int header_sectors = QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
error_setg(errp, "Volume is not in LUKS format");
return -1;
}
if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
error_setg(errp, "LUKS version %" PRIu32 " is not supported",
luks->header.version);
return -1;
}
/* Check all keyslots for corruption */
for (i = 0 ; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS ; i++) {
const QCryptoBlockLUKSKeySlot *slot1 = &luks->header.key_slots[i];
unsigned int start1 = slot1->key_offset_sector;
unsigned int len1 =
qcrypto_block_luks_splitkeylen_sectors(luks,
header_sectors,
slot1->stripes);
if (slot1->stripes == 0) {
error_setg(errp, "Keyslot %zu is corrupted (stripes == 0)", i);
return -1;
}
if (slot1->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED &&
slot1->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
error_setg(errp,
"Keyslot %zu state (active/disable) is corrupted", i);
return -1;
}
if (start1 + len1 > luks->header.payload_offset_sector) {
error_setg(errp,
"Keyslot %zu is overlapping with the encrypted payload",
i);
return -1;
}
for (j = i + 1 ; j < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS ; j++) {
const QCryptoBlockLUKSKeySlot *slot2 = &luks->header.key_slots[j];
unsigned int start2 = slot2->key_offset_sector;
unsigned int len2 =
qcrypto_block_luks_splitkeylen_sectors(luks,
header_sectors,
slot2->stripes);
if (start1 + len1 > start2 && start2 + len2 > start1) {
error_setg(errp,
"Keyslots %zu and %zu are overlapping in the header",
i, j);
return -1;
}
}
}
return 0;
}
/*
* Parses the crypto parameters that are stored in the LUKS header
*/
static int
qcrypto_block_luks_parse_header(QCryptoBlockLUKS *luks, Error **errp)
{
g_autofree char *cipher_mode = g_strdup(luks->header.cipher_mode);
char *ivgen_name, *ivhash_name;
Error *local_err = NULL;
/*
* The cipher_mode header contains a string that we have
* to further parse, of the format
*
* <cipher-mode>-<iv-generator>[:<iv-hash>]
*
* eg cbc-essiv:sha256, cbc-plain64
*/
ivgen_name = strchr(cipher_mode, '-');
if (!ivgen_name) {
error_setg(errp, "Unexpected cipher mode string format %s",
luks->header.cipher_mode);
return -1;
}
*ivgen_name = '\0';
ivgen_name++;
ivhash_name = strchr(ivgen_name, ':');
if (!ivhash_name) {
luks->ivgen_hash_alg = 0;
} else {
*ivhash_name = '\0';
ivhash_name++;
luks->ivgen_hash_alg = qcrypto_block_luks_hash_name_lookup(ivhash_name,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
}
luks->cipher_mode = qcrypto_block_luks_cipher_mode_lookup(cipher_mode,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
luks->cipher_alg =
qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
luks->cipher_mode,
luks->header.master_key_len,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
luks->hash_alg =
qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
luks->ivgen_alg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
if (luks->ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
if (!ivhash_name) {
error_setg(errp, "Missing IV generator hash specification");
return -1;
}
luks->ivgen_cipher_alg =
qcrypto_block_luks_essiv_cipher(luks->cipher_alg,
luks->ivgen_hash_alg,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
} else {
/*
* Note we parsed the ivhash_name earlier in the cipher_mode
* spec string even with plain/plain64 ivgens, but we
* will ignore it, since it is irrelevant for these ivgens.
* This is for compat with dm-crypt which will silently
* ignore hash names with these ivgens rather than report
* an error about the invalid usage
*/
luks->ivgen_cipher_alg = luks->cipher_alg;
}
return 0;
}
/*
* Given a key slot, user password, and the master key,
* will store the encrypted master key there, and update the
* in-memory header. User must then write the in-memory header
*
* Returns:
* 0 if the keyslot was written successfully
* with the provided password
* -1 if a fatal error occurred while storing the key
*/
static int
qcrypto_block_luks_store_key(QCryptoBlock *block,
unsigned int slot_idx,
const char *password,
uint8_t *masterkey,
uint64_t iter_time,
QCryptoBlockWriteFunc writefunc,
void *opaque,
Error **errp)
{
QCryptoBlockLUKS *luks = block->opaque;
QCryptoBlockLUKSKeySlot *slot;
g_autofree uint8_t *splitkey = NULL;
size_t splitkeylen;
g_autofree uint8_t *slotkey = NULL;
g_autoptr(QCryptoCipher) cipher = NULL;
g_autoptr(QCryptoIVGen) ivgen = NULL;
Error *local_err = NULL;
uint64_t iters;
int ret = -1;
assert(slot_idx < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
slot = &luks->header.key_slots[slot_idx];
if (qcrypto_random_bytes(slot->salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
errp) < 0) {
goto cleanup;
}
splitkeylen = luks->header.master_key_len * slot->stripes;
/*
* Determine how many iterations are required to
* hash the user password while consuming 1 second of compute
* time
*/
iters = qcrypto_pbkdf2_count_iters(luks->hash_alg,
(uint8_t *)password, strlen(password),
slot->salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
luks->header.master_key_len,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
goto cleanup;
}
if (iters > (ULLONG_MAX / iter_time)) {
error_setg_errno(errp, ERANGE,
"PBKDF iterations %llu too large to scale",
(unsigned long long)iters);
goto cleanup;
}
/* iter_time was in millis, but count_iters reported for secs */
iters = iters * iter_time / 1000;
if (iters > UINT32_MAX) {
error_setg_errno(errp, ERANGE,
"PBKDF iterations %llu larger than %u",
(unsigned long long)iters, UINT32_MAX);
goto cleanup;
}
slot->iterations =
MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
/*
* Generate a key that we'll use to encrypt the master
* key, from the user's password
*/
slotkey = g_new0(uint8_t, luks->header.master_key_len);
if (qcrypto_pbkdf2(luks->hash_alg,
(uint8_t *)password, strlen(password),
slot->salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
slot->iterations,
slotkey, luks->header.master_key_len,
errp) < 0) {
goto cleanup;
}
/*
* Setup the encryption objects needed to encrypt the
* master key material
*/
cipher = qcrypto_cipher_new(luks->cipher_alg,
luks->cipher_mode,
slotkey, luks->header.master_key_len,
errp);
if (!cipher) {
goto cleanup;
}
ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
luks->ivgen_cipher_alg,
luks->ivgen_hash_alg,
slotkey, luks->header.master_key_len,
errp);
if (!ivgen) {
goto cleanup;
}
/*
* Before storing the master key, we need to vastly
* increase its size, as protection against forensic
* disk data recovery
*/
splitkey = g_new0(uint8_t, splitkeylen);
if (qcrypto_afsplit_encode(luks->hash_alg,
luks->header.master_key_len,
slot->stripes,
masterkey,
splitkey,
errp) < 0) {
goto cleanup;
}
/*
* Now we encrypt the split master key with the key generated
* from the user's password, before storing it
*/
if (qcrypto_block_cipher_encrypt_helper(cipher, block->niv, ivgen,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
0,
splitkey,
splitkeylen,
errp) < 0) {
goto cleanup;
}
/* Write out the slot's master key material. */
if (writefunc(block,
slot->key_offset_sector *
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
splitkey, splitkeylen,
opaque,
errp) != splitkeylen) {
goto cleanup;
}
slot->active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
if (qcrypto_block_luks_store_header(block, writefunc, opaque, errp) < 0) {
goto cleanup;
}
ret = 0;
cleanup:
if (slotkey) {
memset(slotkey, 0, luks->header.master_key_len);
}
if (splitkey) {
memset(splitkey, 0, splitkeylen);
}
return ret;
}
/*
* Given a key slot, and user password, this will attempt to unlock
* the master encryption key from the key slot.
*
* Returns:
* 0 if the key slot is disabled, or key could not be decrypted
* with the provided password
* 1 if the key slot is enabled, and key decrypted successfully
* with the provided password
* -1 if a fatal error occurred loading the key
*/
static int
qcrypto_block_luks_load_key(QCryptoBlock *block,
size_t slot_idx,
const char *password,
uint8_t *masterkey,
QCryptoBlockReadFunc readfunc,
void *opaque,
Error **errp)
{
QCryptoBlockLUKS *luks = block->opaque;
const QCryptoBlockLUKSKeySlot *slot;
g_autofree uint8_t *splitkey = NULL;
size_t splitkeylen;
g_autofree uint8_t *possiblekey = NULL;
ssize_t rv;
g_autoptr(QCryptoCipher) cipher = NULL;
uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
g_autoptr(QCryptoIVGen) ivgen = NULL;
size_t niv;
assert(slot_idx < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
slot = &luks->header.key_slots[slot_idx];
if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
return 0;
}
splitkeylen = luks->header.master_key_len * slot->stripes;
splitkey = g_new0(uint8_t, splitkeylen);
possiblekey = g_new0(uint8_t, luks->header.master_key_len);
/*
* The user password is used to generate a (possible)
* decryption key. This may or may not successfully
* decrypt the master key - we just blindly assume
* the key is correct and validate the results of
* decryption later.
*/
if (qcrypto_pbkdf2(luks->hash_alg,
(const uint8_t *)password, strlen(password),
slot->salt, QCRYPTO_BLOCK_LUKS_SALT_LEN,
slot->iterations,
possiblekey, luks->header.master_key_len,
errp) < 0) {
return -1;
}
/*
* We need to read the master key material from the
* LUKS key material header. What we're reading is
* not the raw master key, but rather the data after
* it has been passed through AFSplit and the result
* then encrypted.
*/
rv = readfunc(block,
slot->key_offset_sector * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
splitkey, splitkeylen,
opaque,
errp);
if (rv < 0) {
return -1;
}
/* Setup the cipher/ivgen that we'll use to try to decrypt
* the split master key material */
cipher = qcrypto_cipher_new(luks->cipher_alg,
luks->cipher_mode,
possiblekey,
luks->header.master_key_len,
errp);
if (!cipher) {
return -1;
}
niv = qcrypto_cipher_get_iv_len(luks->cipher_alg,
luks->cipher_mode);
ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
luks->ivgen_cipher_alg,
luks->ivgen_hash_alg,
possiblekey,
luks->header.master_key_len,
errp);
if (!ivgen) {
return -1;
}
/*
* The master key needs to be decrypted in the same
* way that the block device payload will be decrypted
* later. In particular we'll be using the IV generator
* to reset the encryption cipher every time the master
* key crosses a sector boundary.
*/
if (qcrypto_block_cipher_decrypt_helper(cipher,
niv,
ivgen,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
0,
splitkey,
splitkeylen,
errp) < 0) {
return -1;
}
/*
* Now we've decrypted the split master key, join
* it back together to get the actual master key.
*/
if (qcrypto_afsplit_decode(luks->hash_alg,
luks->header.master_key_len,
slot->stripes,
splitkey,
masterkey,
errp) < 0) {
return -1;
}
/*
* We still don't know that the masterkey we got is valid,
* because we just blindly assumed the user's password
* was correct. This is where we now verify it. We are
* creating a hash of the master key using PBKDF and
* then comparing that to the hash stored in the key slot
* header
*/
if (qcrypto_pbkdf2(luks->hash_alg,
masterkey,
luks->header.master_key_len,
luks->header.master_key_salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
luks->header.master_key_iterations,
keydigest,
G_N_ELEMENTS(keydigest),
errp) < 0) {
return -1;
}
if (memcmp(keydigest, luks->header.master_key_digest,
QCRYPTO_BLOCK_LUKS_DIGEST_LEN) == 0) {
/* Success, we got the right master key */
return 1;
}
/* Fail, user's password was not valid for this key slot,
* tell caller to try another slot */
return 0;
}
/*
* Given a user password, this will iterate over all key
* slots and try to unlock each active key slot using the
* password until it successfully obtains a master key.
*
* Returns 0 if a key was loaded, -1 if no keys could be loaded
*/
static int
qcrypto_block_luks_find_key(QCryptoBlock *block,
const char *password,
uint8_t *masterkey,
QCryptoBlockReadFunc readfunc,
void *opaque,
Error **errp)
{
size_t i;
int rv;
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
rv = qcrypto_block_luks_load_key(block,
i,
password,
masterkey,
readfunc,
opaque,
errp);
if (rv < 0) {
goto error;
}
if (rv == 1) {
return 0;
}
}
error_setg(errp, "Invalid password, cannot unlock any keyslot");
error:
return -1;
}
/*
* Returns true if a slot i is marked as active
* (contains encrypted copy of the master key)
*/
static bool
qcrypto_block_luks_slot_active(const QCryptoBlockLUKS *luks,
unsigned int slot_idx)
{
uint32_t val;
assert(slot_idx < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
val = luks->header.key_slots[slot_idx].active;
return val == QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
}
/*
* Returns the number of slots that are marked as active
* (slots that contain encrypted copy of the master key)
*/
static unsigned int
qcrypto_block_luks_count_active_slots(const QCryptoBlockLUKS *luks)
{
size_t i = 0;
unsigned int ret = 0;
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
if (qcrypto_block_luks_slot_active(luks, i)) {
ret++;
}
}
return ret;
}
/*
* Finds first key slot which is not active
* Returns the key slot index, or -1 if it doesn't exist
*/
static int
qcrypto_block_luks_find_free_keyslot(const QCryptoBlockLUKS *luks)
{
size_t i;
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
if (!qcrypto_block_luks_slot_active(luks, i)) {
return i;
}
}
return -1;
}
/*
* Erases an keyslot given its index
* Returns:
* 0 if the keyslot was erased successfully
* -1 if a error occurred while erasing the keyslot
*
*/
static int
qcrypto_block_luks_erase_key(QCryptoBlock *block,
unsigned int slot_idx,
QCryptoBlockWriteFunc writefunc,
void *opaque,
Error **errp)
{
QCryptoBlockLUKS *luks = block->opaque;
QCryptoBlockLUKSKeySlot *slot;
g_autofree uint8_t *garbagesplitkey = NULL;
size_t splitkeylen;
size_t i;
Error *local_err = NULL;
int ret;
assert(slot_idx < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
slot = &luks->header.key_slots[slot_idx];
splitkeylen = luks->header.master_key_len * slot->stripes;
assert(splitkeylen > 0);
garbagesplitkey = g_new0(uint8_t, splitkeylen);
/* Reset the key slot header */
memset(slot->salt, 0, QCRYPTO_BLOCK_LUKS_SALT_LEN);
slot->iterations = 0;
slot->active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
ret = qcrypto_block_luks_store_header(block, writefunc,
opaque, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
}
/*
* Now try to erase the key material, even if the header
* update failed
*/
for (i = 0; i < QCRYPTO_BLOCK_LUKS_ERASE_ITERATIONS; i++) {
if (qcrypto_random_bytes(garbagesplitkey,
splitkeylen, &local_err) < 0) {
/*
* If we failed to get the random data, still write
* at least zeros to the key slot at least once
*/
error_propagate(errp, local_err);
if (i > 0) {
return -1;
}
}
if (writefunc(block,
slot->key_offset_sector * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
garbagesplitkey,
splitkeylen,
opaque,
&local_err) != splitkeylen) {
error_propagate(errp, local_err);
return -1;
}
}
return ret;
}
static int
qcrypto_block_luks_open(QCryptoBlock *block,
QCryptoBlockOpenOptions *options,
const char *optprefix,
QCryptoBlockReadFunc readfunc,
void *opaque,
unsigned int flags,
size_t n_threads,
Error **errp)
{
QCryptoBlockLUKS *luks = NULL;
g_autofree uint8_t *masterkey = NULL;
g_autofree char *password = NULL;
if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
if (!options->u.luks.key_secret) {
error_setg(errp, "Parameter '%skey-secret' is required for cipher",
optprefix ? optprefix : "");
return -1;
}
password = qcrypto_secret_lookup_as_utf8(
options->u.luks.key_secret, errp);
if (!password) {
return -1;
}
}
luks = g_new0(QCryptoBlockLUKS, 1);
block->opaque = luks;
luks->secret = g_strdup(options->u.luks.key_secret);
if (qcrypto_block_luks_load_header(block, readfunc, opaque, errp) < 0) {
goto fail;
}
if (qcrypto_block_luks_check_header(luks, errp) < 0) {
goto fail;
}
if (qcrypto_block_luks_parse_header(luks, errp) < 0) {
goto fail;
}
if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
/* Try to find which key slot our password is valid for
* and unlock the master key from that slot.
*/
masterkey = g_new0(uint8_t, luks->header.master_key_len);
if (qcrypto_block_luks_find_key(block,
password,
masterkey,
readfunc, opaque,
errp) < 0) {
goto fail;
}
/* We have a valid master key now, so can setup the
* block device payload decryption objects
*/
block->kdfhash = luks->hash_alg;
block->niv = qcrypto_cipher_get_iv_len(luks->cipher_alg,
luks->cipher_mode);
block->ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
luks->ivgen_cipher_alg,
luks->ivgen_hash_alg,
masterkey,
luks->header.master_key_len,
errp);
if (!block->ivgen) {
goto fail;
}
if (qcrypto_block_init_cipher(block,
luks->cipher_alg,
luks->cipher_mode,
masterkey,
luks->header.master_key_len,
n_threads,
errp) < 0) {
goto fail;
}
}
block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
block->payload_offset = luks->header.payload_offset_sector *
block->sector_size;
return 0;
fail:
qcrypto_block_free_cipher(block);
qcrypto_ivgen_free(block->ivgen);
g_free(luks->secret);
g_free(luks);
return -1;
}
static void
qcrypto_block_luks_uuid_gen(uint8_t *uuidstr)
{
QemuUUID uuid;
qemu_uuid_generate(&uuid);
qemu_uuid_unparse(&uuid, (char *)uuidstr);
}
static int
qcrypto_block_luks_create(QCryptoBlock *block,
QCryptoBlockCreateOptions *options,
const char *optprefix,
QCryptoBlockInitFunc initfunc,
QCryptoBlockWriteFunc writefunc,
void *opaque,
Error **errp)
{
QCryptoBlockLUKS *luks;
QCryptoBlockCreateOptionsLUKS luks_opts;
Error *local_err = NULL;
g_autofree uint8_t *masterkey = NULL;
size_t header_sectors;
size_t split_key_sectors;
size_t i;
g_autofree char *password = NULL;
const char *cipher_alg;
const char *cipher_mode;
const char *ivgen_alg;
const char *ivgen_hash_alg = NULL;
const char *hash_alg;
g_autofree char *cipher_mode_spec = NULL;
uint64_t iters;
memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
if (!luks_opts.has_iter_time) {
luks_opts.iter_time = QCRYPTO_BLOCK_LUKS_DEFAULT_ITER_TIME_MS;
}
if (!luks_opts.has_cipher_alg) {
luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
}
if (!luks_opts.has_cipher_mode) {
luks_opts.cipher_mode = QCRYPTO_CIPHER_MODE_XTS;
}
if (!luks_opts.has_ivgen_alg) {
luks_opts.ivgen_alg = QCRYPTO_IVGEN_ALG_PLAIN64;
}
if (!luks_opts.has_hash_alg) {
luks_opts.hash_alg = QCRYPTO_HASH_ALG_SHA256;
}
if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
if (!luks_opts.has_ivgen_hash_alg) {
luks_opts.ivgen_hash_alg = QCRYPTO_HASH_ALG_SHA256;
luks_opts.has_ivgen_hash_alg = true;
}
}
luks = g_new0(QCryptoBlockLUKS, 1);
block->opaque = luks;
luks->cipher_alg = luks_opts.cipher_alg;
luks->cipher_mode = luks_opts.cipher_mode;
luks->ivgen_alg = luks_opts.ivgen_alg;
luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
luks->hash_alg = luks_opts.hash_alg;
/* Note we're allowing ivgen_hash_alg to be set even for
* non-essiv iv generators that don't need a hash. It will
* be silently ignored, for compatibility with dm-crypt */
if (!options->u.luks.key_secret) {
error_setg(errp, "Parameter '%skey-secret' is required for cipher",
optprefix ? optprefix : "");
goto error;
}
luks->secret = g_strdup(options->u.luks.key_secret);
password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp);
if (!password) {
goto error;
}
memcpy(luks->header.magic, qcrypto_block_luks_magic,
QCRYPTO_BLOCK_LUKS_MAGIC_LEN);
/* We populate the header in native endianness initially and
* then convert everything to big endian just before writing
* it out to disk
*/
luks->header.version = QCRYPTO_BLOCK_LUKS_VERSION;
qcrypto_block_luks_uuid_gen(luks->header.uuid);
cipher_alg = qcrypto_block_luks_cipher_alg_lookup(luks_opts.cipher_alg,
errp);
if (!cipher_alg) {
goto error;
}
cipher_mode = QCryptoCipherMode_str(luks_opts.cipher_mode);
ivgen_alg = QCryptoIVGenAlgorithm_str(luks_opts.ivgen_alg);
if (luks_opts.has_ivgen_hash_alg) {
ivgen_hash_alg = QCryptoHashAlgorithm_str(luks_opts.ivgen_hash_alg);
cipher_mode_spec = g_strdup_printf("%s-%s:%s", cipher_mode, ivgen_alg,
ivgen_hash_alg);
} else {
cipher_mode_spec = g_strdup_printf("%s-%s", cipher_mode, ivgen_alg);
}
hash_alg = QCryptoHashAlgorithm_str(luks_opts.hash_alg);
if (strlen(cipher_alg) >= QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN) {
error_setg(errp, "Cipher name '%s' is too long for LUKS header",
cipher_alg);
goto error;
}
if (strlen(cipher_mode_spec) >= QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN) {
error_setg(errp, "Cipher mode '%s' is too long for LUKS header",
cipher_mode_spec);
goto error;
}
if (strlen(hash_alg) >= QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN) {
error_setg(errp, "Hash name '%s' is too long for LUKS header",
hash_alg);
goto error;
}
if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
luks->ivgen_cipher_alg =
qcrypto_block_luks_essiv_cipher(luks_opts.cipher_alg,
luks_opts.ivgen_hash_alg,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
goto error;
}
} else {
luks->ivgen_cipher_alg = luks_opts.cipher_alg;
}
strcpy(luks->header.cipher_name, cipher_alg);
strcpy(luks->header.cipher_mode, cipher_mode_spec);
strcpy(luks->header.hash_spec, hash_alg);
luks->header.master_key_len =
qcrypto_cipher_get_key_len(luks_opts.cipher_alg);
if (luks_opts.cipher_mode == QCRYPTO_CIPHER_MODE_XTS) {
luks->header.master_key_len *= 2;
}
/* Generate the salt used for hashing the master key
* with PBKDF later
*/
if (qcrypto_random_bytes(luks->header.master_key_salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
errp) < 0) {
goto error;
}
/* Generate random master key */
masterkey = g_new0(uint8_t, luks->header.master_key_len);
if (qcrypto_random_bytes(masterkey,
luks->header.master_key_len, errp) < 0) {
goto error;
}
/* Setup the block device payload encryption objects */
if (qcrypto_block_init_cipher(block, luks_opts.cipher_alg,
luks_opts.cipher_mode, masterkey,
luks->header.master_key_len, 1, errp) < 0) {
goto error;
}
block->kdfhash = luks_opts.hash_alg;
block->niv = qcrypto_cipher_get_iv_len(luks_opts.cipher_alg,
luks_opts.cipher_mode);
block->ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
luks->ivgen_cipher_alg,
luks_opts.ivgen_hash_alg,
masterkey, luks->header.master_key_len,
errp);
if (!block->ivgen) {
goto error;
}
/* Determine how many iterations we need to hash the master
* key, in order to have 1 second of compute time used
*/
iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
masterkey, luks->header.master_key_len,
luks->header.master_key_salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
goto error;
}
if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
error_setg_errno(errp, ERANGE,
"PBKDF iterations %llu too large to scale",
(unsigned long long)iters);
goto error;
}
/* iter_time was in millis, but count_iters reported for secs */
iters = iters * luks_opts.iter_time / 1000;
/* Why /= 8 ? That matches cryptsetup, but there's no
* explanation why they chose /= 8... Probably so that
* if all 8 keyslots are active we only spend 1 second
* in total time to check all keys */
iters /= 8;
if (iters > UINT32_MAX) {
error_setg_errno(errp, ERANGE,
"PBKDF iterations %llu larger than %u",
(unsigned long long)iters, UINT32_MAX);
goto error;
}
iters = MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS);
luks->header.master_key_iterations = iters;
/* Hash the master key, saving the result in the LUKS
* header. This hash is used when opening the encrypted
* device to verify that the user password unlocked a
* valid master key
*/
if (qcrypto_pbkdf2(luks_opts.hash_alg,
masterkey, luks->header.master_key_len,
luks->header.master_key_salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
luks->header.master_key_iterations,
luks->header.master_key_digest,
QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
errp) < 0) {
goto error;
}
/* start with the sector that follows the header*/
header_sectors = QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
split_key_sectors =
qcrypto_block_luks_splitkeylen_sectors(luks,
header_sectors,
QCRYPTO_BLOCK_LUKS_STRIPES);
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
QCryptoBlockLUKSKeySlot *slot = &luks->header.key_slots[i];
slot->active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
slot->key_offset_sector = header_sectors + i * split_key_sectors;
slot->stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
}
/* The total size of the LUKS headers is the partition header + key
* slot headers, rounded up to the nearest sector, combined with
* the size of each master key material region, also rounded up
* to the nearest sector */
luks->header.payload_offset_sector = header_sectors +
QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS * split_key_sectors;
block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
block->payload_offset = luks->header.payload_offset_sector *
block->sector_size;
/* Reserve header space to match payload offset */
initfunc(block, block->payload_offset, opaque, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto error;
}
/* populate the slot 0 with the password encrypted master key*/
/* This will also store the header */
if (qcrypto_block_luks_store_key(block,
0,
password,
masterkey,
luks_opts.iter_time,
writefunc,
opaque,
errp) < 0) {
goto error;
}
memset(masterkey, 0, luks->header.master_key_len);
return 0;
error:
if (masterkey) {
memset(masterkey, 0, luks->header.master_key_len);
}
qcrypto_block_free_cipher(block);
qcrypto_ivgen_free(block->ivgen);
g_free(luks->secret);
g_free(luks);
return -1;
}
static int
qcrypto_block_luks_amend_add_keyslot(QCryptoBlock *block,
QCryptoBlockReadFunc readfunc,
QCryptoBlockWriteFunc writefunc,
void *opaque,
QCryptoBlockAmendOptionsLUKS *opts_luks,
bool force,
Error **errp)
{
QCryptoBlockLUKS *luks = block->opaque;
uint64_t iter_time = opts_luks->has_iter_time ?
opts_luks->iter_time :
QCRYPTO_BLOCK_LUKS_DEFAULT_ITER_TIME_MS;
int keyslot;
g_autofree char *old_password = NULL;
g_autofree char *new_password = NULL;
g_autofree uint8_t *master_key = NULL;
char *secret = opts_luks->has_secret ? opts_luks->secret : luks->secret;
if (!opts_luks->has_new_secret) {
error_setg(errp, "'new-secret' is required to activate a keyslot");
return -1;
}
if (opts_luks->has_old_secret) {
error_setg(errp,
"'old-secret' must not be given when activating keyslots");
return -1;
}
if (opts_luks->has_keyslot) {
keyslot = opts_luks->keyslot;
if (keyslot < 0 || keyslot >= QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS) {
error_setg(errp,
"Invalid keyslot %u specified, must be between 0 and %u",
keyslot, QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS - 1);
return -1;
}
} else {
keyslot = qcrypto_block_luks_find_free_keyslot(luks);
if (keyslot == -1) {
error_setg(errp,
"Can't add a keyslot - all keyslots are in use");
return -1;
}
}
if (!force && qcrypto_block_luks_slot_active(luks, keyslot)) {
error_setg(errp,
"Refusing to overwrite active keyslot %i - "
"please erase it first",
keyslot);
return -1;
}
/* Locate the password that will be used to retrieve the master key */
old_password = qcrypto_secret_lookup_as_utf8(secret, errp);
if (!old_password) {
return -1;
}
/* Retrieve the master key */
master_key = g_new0(uint8_t, luks->header.master_key_len);
if (qcrypto_block_luks_find_key(block, old_password, master_key,
readfunc, opaque, errp) < 0) {
error_append_hint(errp, "Failed to retrieve the master key");
return -1;
}
/* Locate the new password*/
new_password = qcrypto_secret_lookup_as_utf8(opts_luks->new_secret, errp);
if (!new_password) {
return -1;
}
/* Now set the new keyslots */
if (qcrypto_block_luks_store_key(block, keyslot, new_password, master_key,
iter_time, writefunc, opaque, errp)) {
error_append_hint(errp, "Failed to write to keyslot %i", keyslot);
return -1;
}
return 0;
}
static int
qcrypto_block_luks_amend_erase_keyslots(QCryptoBlock *block,
QCryptoBlockReadFunc readfunc,
QCryptoBlockWriteFunc writefunc,
void *opaque,
QCryptoBlockAmendOptionsLUKS *opts_luks,
bool force,
Error **errp)
{
QCryptoBlockLUKS *luks = block->opaque;
g_autofree uint8_t *tmpkey = NULL;
g_autofree char *old_password = NULL;
if (opts_luks->has_new_secret) {
error_setg(errp,
"'new-secret' must not be given when erasing keyslots");
return -1;
}
if (opts_luks->has_iter_time) {
error_setg(errp,
"'iter-time' must not be given when erasing keyslots");
return -1;
}
if (opts_luks->has_secret) {
error_setg(errp,
"'secret' must not be given when erasing keyslots");
return -1;
}
/* Load the old password if given */
if (opts_luks->has_old_secret) {
old_password = qcrypto_secret_lookup_as_utf8(opts_luks->old_secret,
errp);
if (!old_password) {
return -1;
}
/*
* Allocate a temporary key buffer that we will need when
* checking if slot matches the given old password
*/
tmpkey = g_new0(uint8_t, luks->header.master_key_len);
}
/* Erase an explicitly given keyslot */
if (opts_luks->has_keyslot) {
int keyslot = opts_luks->keyslot;
if (keyslot < 0 || keyslot >= QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS) {
error_setg(errp,
"Invalid keyslot %i specified, must be between 0 and %i",
keyslot, QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS - 1);
return -1;
}
if (opts_luks->has_old_secret) {
int rv = qcrypto_block_luks_load_key(block,
keyslot,
old_password,
tmpkey,
readfunc,
opaque,
errp);
if (rv == -1) {
return -1;
} else if (rv == 0) {
error_setg(errp,
"Given keyslot %i doesn't contain the given "
"old password for erase operation",
keyslot);
return -1;
}
}
if (!force && !qcrypto_block_luks_slot_active(luks, keyslot)) {
error_setg(errp,
"Given keyslot %i is already erased (inactive) ",
keyslot);
return -1;
}
if (!force && qcrypto_block_luks_count_active_slots(luks) == 1) {
error_setg(errp,
"Attempt to erase the only active keyslot %i "
"which will erase all the data in the image "
"irreversibly - refusing operation",
keyslot);
return -1;
}
if (qcrypto_block_luks_erase_key(block, keyslot,
writefunc, opaque, errp)) {
error_append_hint(errp, "Failed to erase keyslot %i", keyslot);
return -1;
}
/* Erase all keyslots that match the given old password */
} else if (opts_luks->has_old_secret) {
unsigned long slots_to_erase_bitmap = 0;
size_t i;
int slot_count;
assert(QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS <=
sizeof(slots_to_erase_bitmap) * 8);
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
int rv = qcrypto_block_luks_load_key(block,
i,
old_password,
tmpkey,
readfunc,
opaque,
errp);
if (rv == -1) {
return -1;
} else if (rv == 1) {
bitmap_set(&slots_to_erase_bitmap, i, 1);
}
}
slot_count = bitmap_count_one(&slots_to_erase_bitmap,
QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
if (slot_count == 0) {
error_setg(errp,
"No keyslots match given (old) password for erase operation");
return -1;
}
if (!force &&
slot_count == qcrypto_block_luks_count_active_slots(luks)) {
error_setg(errp,
"All the active keyslots match the (old) password that "
"was given and erasing them will erase all the data in "
"the image irreversibly - refusing operation");
return -1;
}
/* Now apply the update */
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
if (!test_bit(i, &slots_to_erase_bitmap)) {
continue;
}
if (qcrypto_block_luks_erase_key(block, i, writefunc,
opaque, errp)) {
error_append_hint(errp, "Failed to erase keyslot %zu", i);
return -1;
}
}
} else {
error_setg(errp,
"To erase keyslot(s), either explicit keyslot index "
"or the password currently contained in them must be given");
return -1;
}
return 0;
}
static int
qcrypto_block_luks_amend_options(QCryptoBlock *block,
QCryptoBlockReadFunc readfunc,
QCryptoBlockWriteFunc writefunc,
void *opaque,
QCryptoBlockAmendOptions *options,
bool force,
Error **errp)
{
QCryptoBlockAmendOptionsLUKS *opts_luks = &options->u.luks;
switch (opts_luks->state) {
case Q_CRYPTO_BLOCKLUKS_KEYSLOT_STATE_ACTIVE:
return qcrypto_block_luks_amend_add_keyslot(block, readfunc,
writefunc, opaque,
opts_luks, force, errp);
case Q_CRYPTO_BLOCKLUKS_KEYSLOT_STATE_INACTIVE:
return qcrypto_block_luks_amend_erase_keyslots(block, readfunc,
writefunc, opaque,
opts_luks, force, errp);
default:
g_assert_not_reached();
}
}
static int qcrypto_block_luks_get_info(QCryptoBlock *block,
QCryptoBlockInfo *info,
Error **errp)
{
QCryptoBlockLUKS *luks = block->opaque;
QCryptoBlockInfoLUKSSlot *slot;
QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
size_t i;
info->u.luks.cipher_alg = luks->cipher_alg;
info->u.luks.cipher_mode = luks->cipher_mode;
info->u.luks.ivgen_alg = luks->ivgen_alg;
if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
info->u.luks.has_ivgen_hash_alg = true;
info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
}
info->u.luks.hash_alg = luks->hash_alg;
info->u.luks.payload_offset = block->payload_offset;
info->u.luks.master_key_iters = luks->header.master_key_iterations;
info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
sizeof(luks->header.uuid));
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
*prev = slots;
slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
slot->active = luks->header.key_slots[i].active ==
QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
slot->key_offset = luks->header.key_slots[i].key_offset_sector
* QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
if (slot->active) {
slot->has_iters = true;
slot->iters = luks->header.key_slots[i].iterations;
slot->has_stripes = true;
slot->stripes = luks->header.key_slots[i].stripes;
}
prev = &slots->next;
}
return 0;
}
static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
{
QCryptoBlockLUKS *luks = block->opaque;
if (luks) {
g_free(luks->secret);
g_free(luks);
}
}
static int
qcrypto_block_luks_decrypt(QCryptoBlock *block,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
return qcrypto_block_decrypt_helper(block,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
offset, buf, len, errp);
}
static int
qcrypto_block_luks_encrypt(QCryptoBlock *block,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
return qcrypto_block_encrypt_helper(block,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
offset, buf, len, errp);
}
const QCryptoBlockDriver qcrypto_block_driver_luks = {
.open = qcrypto_block_luks_open,
.create = qcrypto_block_luks_create,
.amend = qcrypto_block_luks_amend_options,
.get_info = qcrypto_block_luks_get_info,
.cleanup = qcrypto_block_luks_cleanup,
.decrypt = qcrypto_block_luks_decrypt,
.encrypt = qcrypto_block_luks_encrypt,
.has_format = qcrypto_block_luks_has_format,
};
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