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xemu/crypto/block-luks.c
Daniel P. Berrangé 6c1989321e crypto: quote algorithm names in error messages 
If given a malformed LUKS header, it is possible that the algorithm
names end up being an empty string. This leads to confusing error
messages unless quoting is used to highlight where the empty string
is subsituted in the error message.

Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2022-10-27 12:55:27 +01:00

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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 "block-luks-priv.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 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 },
};
QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSKeySlot) != 48);
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);
}
void
qcrypto_block_luks_to_disk_endian(QCryptoBlockLUKSHeader *hdr)
{
size_t i;
/*
* Everything on disk uses Big Endian (tm), so flip header fields
* before writing them
*/
cpu_to_be16s(&hdr->version);
cpu_to_be32s(&hdr->payload_offset_sector);
cpu_to_be32s(&hdr->master_key_len);
cpu_to_be32s(&hdr->master_key_iterations);
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
cpu_to_be32s(&hdr->key_slots[i].active);
cpu_to_be32s(&hdr->key_slots[i].iterations);
cpu_to_be32s(&hdr->key_slots[i].key_offset_sector);
cpu_to_be32s(&hdr->key_slots[i].stripes);
}
}
void
qcrypto_block_luks_from_disk_endian(QCryptoBlockLUKSHeader *hdr)
{
size_t i;
/*
* The header is always stored in big-endian format, so
* convert everything to native
*/
be16_to_cpus(&hdr->version);
be32_to_cpus(&hdr->payload_offset_sector);
be32_to_cpus(&hdr->master_key_len);
be32_to_cpus(&hdr->master_key_iterations);
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
be32_to_cpus(&hdr->key_slots[i].active);
be32_to_cpus(&hdr->key_slots[i].iterations);
be32_to_cpus(&hdr->key_slots[i].key_offset_sector);
be32_to_cpus(&hdr->key_slots[i].stripes);
}
}
/*
* 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;
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));
qcrypto_block_luks_to_disk_endian(hdr_copy);
/* 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)
{
int rv;
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;
}
qcrypto_block_luks_from_disk_endian(&luks->header);
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;
}
if (!memchr(luks->header.cipher_name, '\0',
sizeof(luks->header.cipher_name))) {
error_setg(errp, "LUKS header cipher name is not NUL terminated");
return -1;
}
if (!memchr(luks->header.cipher_mode, '\0',
sizeof(luks->header.cipher_mode))) {
error_setg(errp, "LUKS header cipher mode is not NUL terminated");
return -1;
}
if (!memchr(luks->header.hash_spec, '\0',
sizeof(luks->header.hash_spec))) {
error_setg(errp, "LUKS header hash spec is not NUL terminated");
return -1;
}
if (luks->header.payload_offset_sector <
DIV_ROUND_UP(QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) {
error_setg(errp, "LUKS payload is overlapping with the header");
return -1;
}
if (luks->header.master_key_iterations == 0) {
error_setg(errp, "LUKS key iteration count is zero");
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 != QCRYPTO_BLOCK_LUKS_STRIPES) {
error_setg(errp, "Keyslot %zu is corrupted (stripes %d != %d)",
i, slot1->stripes, QCRYPTO_BLOCK_LUKS_STRIPES);
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 (slot1->active == QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED &&
slot1->iterations == 0) {
error_setg(errp, "Keyslot %zu iteration count is zero", i);
return -1;
}
if (start1 < DIV_ROUND_UP(QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) {
error_setg(errp,
"Keyslot %zu is overlapping with the LUKS header",
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) < 0) {
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;
int 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) < 0) {
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 **tail = &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++) {
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;
}
QAPI_LIST_APPEND(tail, slot);
}
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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