diff options
Diffstat (limited to 'crypto/block-luks.c')
| -rw-r--r-- | crypto/block-luks.c | 1328 |
1 files changed, 1328 insertions, 0 deletions
diff --git a/crypto/block-luks.c b/crypto/block-luks.c new file mode 100644 index 0000000000..58c1b940e1 --- /dev/null +++ b/crypto/block-luks.c @@ -0,0 +1,1328 @@ +/* + * 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 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 "crypto/block-luks.h" + +#include "crypto/hash.h" +#include "crypto/afsplit.h" +#include "crypto/pbkdf.h" +#include "crypto/secret.h" +#include "crypto/random.h" + +#ifdef CONFIG_UUID +#include <uuid/uuid.h> +#endif + +#include "qemu/coroutine.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 + +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; + /* number of anti-forensic stripes */ + uint32_t stripes; +} QEMU_PACKED; + +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; + + /* Number of key bytes */ + uint32_t key_bytes; + + /* 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_PACKED; + +QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592); + + +struct QCryptoBlockLUKS { + QCryptoBlockLUKSHeader header; +}; + + +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_lookup[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 char *const *map, + size_t maplen, + const char *type, + Error **errp) +{ + size_t i; + for (i = 0; i < maplen; i++) { + if (g_str_equal(map[i], name)) { + return i; + } + } + + error_setg(errp, "%s %s not supported", type, name); + return 0; +} + +#define qcrypto_block_luks_cipher_mode_lookup(name, errp) \ + qcrypto_block_luks_name_lookup(name, \ + QCryptoCipherMode_lookup, \ + QCRYPTO_CIPHER_MODE__MAX, \ + "Cipher mode", \ + errp) + +#define qcrypto_block_luks_hash_name_lookup(name, errp) \ + qcrypto_block_luks_name_lookup(name, \ + QCryptoHashAlgorithm_lookup, \ + QCRYPTO_HASH_ALG__MAX, \ + "Hash algorithm", \ + errp) + +#define qcrypto_block_luks_ivgen_name_lookup(name, errp) \ + qcrypto_block_luks_name_lookup(name, \ + QCryptoIVGenAlgorithm_lookup, \ + QCRYPTO_IVGEN_ALG__MAX, \ + "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_lookup[cipher]); + return 0; + } +} + +/* + * 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, + QCryptoBlockLUKSKeySlot *slot, + const char *password, + QCryptoCipherAlgorithm cipheralg, + QCryptoCipherMode ciphermode, + QCryptoHashAlgorithm hash, + QCryptoIVGenAlgorithm ivalg, + QCryptoCipherAlgorithm ivcipheralg, + QCryptoHashAlgorithm ivhash, + uint8_t *masterkey, + size_t masterkeylen, + QCryptoBlockReadFunc readfunc, + void *opaque, + Error **errp) +{ + QCryptoBlockLUKS *luks = block->opaque; + uint8_t *splitkey; + size_t splitkeylen; + uint8_t *possiblekey; + int ret = -1; + ssize_t rv; + QCryptoCipher *cipher = NULL; + uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN]; + QCryptoIVGen *ivgen = NULL; + size_t niv; + + if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) { + return 0; + } + + splitkeylen = masterkeylen * slot->stripes; + splitkey = g_new0(uint8_t, splitkeylen); + possiblekey = g_new0(uint8_t, masterkeylen); + + /* + * 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(hash, + (const uint8_t *)password, strlen(password), + slot->salt, QCRYPTO_BLOCK_LUKS_SALT_LEN, + slot->iterations, + possiblekey, masterkeylen, + errp) < 0) { + goto cleanup; + } + + /* + * 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 * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE, + splitkey, splitkeylen, + errp, + opaque); + if (rv < 0) { + goto cleanup; + } + + + /* Setup the cipher/ivgen that we'll use to try to decrypt + * the split master key material */ + cipher = qcrypto_cipher_new(cipheralg, ciphermode, + possiblekey, masterkeylen, + errp); + if (!cipher) { + goto cleanup; + } + + niv = qcrypto_cipher_get_iv_len(cipheralg, + ciphermode); + ivgen = qcrypto_ivgen_new(ivalg, + ivcipheralg, + ivhash, + possiblekey, masterkeylen, + errp); + if (!ivgen) { + goto cleanup; + } + + + /* + * 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_decrypt_helper(cipher, + niv, + ivgen, + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE, + 0, + splitkey, + splitkeylen, + errp) < 0) { + goto cleanup; + } + + /* + * Now we've decrypted the split master key, join + * it back together to get the actual master key. + */ + if (qcrypto_afsplit_decode(hash, + masterkeylen, + slot->stripes, + splitkey, + masterkey, + errp) < 0) { + goto cleanup; + } + + + /* + * 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(hash, + masterkey, masterkeylen, + luks->header.master_key_salt, + QCRYPTO_BLOCK_LUKS_SALT_LEN, + luks->header.master_key_iterations, + keydigest, G_N_ELEMENTS(keydigest), + errp) < 0) { + goto cleanup; + } + + if (memcmp(keydigest, luks->header.master_key_digest, + QCRYPTO_BLOCK_LUKS_DIGEST_LEN) == 0) { + /* Success, we got the right master key */ + ret = 1; + goto cleanup; + } + + /* Fail, user's password was not valid for this key slot, + * tell caller to try another slot */ + ret = 0; + + cleanup: + qcrypto_ivgen_free(ivgen); + qcrypto_cipher_free(cipher); + g_free(splitkey); + g_free(possiblekey); + return ret; +} + + +/* + * 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, + QCryptoCipherAlgorithm cipheralg, + QCryptoCipherMode ciphermode, + QCryptoHashAlgorithm hash, + QCryptoIVGenAlgorithm ivalg, + QCryptoCipherAlgorithm ivcipheralg, + QCryptoHashAlgorithm ivhash, + uint8_t **masterkey, + size_t *masterkeylen, + QCryptoBlockReadFunc readfunc, + void *opaque, + Error **errp) +{ + QCryptoBlockLUKS *luks = block->opaque; + size_t i; + int rv; + + *masterkey = g_new0(uint8_t, luks->header.key_bytes); + *masterkeylen = luks->header.key_bytes; + + for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) { + rv = qcrypto_block_luks_load_key(block, + &luks->header.key_slots[i], + password, + cipheralg, + ciphermode, + hash, + ivalg, + ivcipheralg, + ivhash, + *masterkey, + *masterkeylen, + readfunc, + opaque, + errp); + if (rv < 0) { + goto error; + } + if (rv == 1) { + return 0; + } + } + + error_setg(errp, "Invalid password, cannot unlock any keyslot"); + + error: + g_free(*masterkey); + *masterkey = NULL; + *masterkeylen = 0; + return -1; +} + + +static int +qcrypto_block_luks_open(QCryptoBlock *block, + QCryptoBlockOpenOptions *options, + QCryptoBlockReadFunc readfunc, + void *opaque, + unsigned int flags, + Error **errp) +{ + QCryptoBlockLUKS *luks; + Error *local_err = NULL; + int ret = 0; + size_t i; + ssize_t rv; + uint8_t *masterkey = NULL; + size_t masterkeylen; + char *ivgen_name, *ivhash_name; + QCryptoCipherMode ciphermode; + QCryptoCipherAlgorithm cipheralg; + QCryptoIVGenAlgorithm ivalg; + QCryptoCipherAlgorithm ivcipheralg; + QCryptoHashAlgorithm hash; + QCryptoHashAlgorithm ivhash; + char *password = NULL; + + if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) { + if (!options->u.luks.key_secret) { + error_setg(errp, "Parameter 'key-secret' is required for cipher"); + 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; + + /* Read the entire LUKS header, minus the key material from + * the underlying device */ + rv = readfunc(block, 0, + (uint8_t *)&luks->header, + sizeof(luks->header), + errp, + opaque); + if (rv < 0) { + ret = rv; + goto fail; + } + + /* 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); + be32_to_cpus(&luks->header.key_bytes); + 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); + be32_to_cpus(&luks->header.key_slots[i].stripes); + } + + if (memcmp(luks->header.magic, qcrypto_block_luks_magic, + QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) { + error_setg(errp, "Volume is not in LUKS format"); + ret = -EINVAL; + goto fail; + } + if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) { + error_setg(errp, "LUKS version %" PRIu32 " is not supported", + luks->header.version); + ret = -ENOTSUP; + goto fail; + } + + /* + * 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(luks->header.cipher_mode, '-'); + if (!ivgen_name) { + ret = -EINVAL; + error_setg(errp, "Unexpected cipher mode string format %s", + luks->header.cipher_mode); + goto fail; + } + *ivgen_name = '\0'; + ivgen_name++; + + ivhash_name = strchr(ivgen_name, ':'); + if (!ivhash_name) { + ivhash = 0; + } else { + *ivhash_name = '\0'; + ivhash_name++; + + ivhash = qcrypto_block_luks_hash_name_lookup(ivhash_name, + &local_err); + if (local_err) { + ret = -ENOTSUP; + error_propagate(errp, local_err); + goto fail; + } + } + + ciphermode = qcrypto_block_luks_cipher_mode_lookup(luks->header.cipher_mode, + &local_err); + if (local_err) { + ret = -ENOTSUP; + error_propagate(errp, local_err); + goto fail; + } + + cipheralg = qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name, + ciphermode, + luks->header.key_bytes, + &local_err); + if (local_err) { + ret = -ENOTSUP; + error_propagate(errp, local_err); + goto fail; + } + + hash = qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec, + &local_err); + if (local_err) { + ret = -ENOTSUP; + error_propagate(errp, local_err); + goto fail; + } + + ivalg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name, + &local_err); + if (local_err) { + ret = -ENOTSUP; + error_propagate(errp, local_err); + goto fail; + } + + if (ivalg == QCRYPTO_IVGEN_ALG_ESSIV) { + ivcipheralg = qcrypto_block_luks_essiv_cipher(cipheralg, + ivhash, + &local_err); + if (local_err) { + ret = -ENOTSUP; + error_propagate(errp, local_err); + goto fail; + } + } else { + ivcipheralg = cipheralg; + } + + 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. + */ + if (qcrypto_block_luks_find_key(block, + password, + cipheralg, ciphermode, + hash, + ivalg, + ivcipheralg, + ivhash, + &masterkey, &masterkeylen, + readfunc, opaque, + errp) < 0) { + ret = -EACCES; + goto fail; + } + + /* We have a valid master key now, so can setup the + * block device payload decryption objects + */ + block->kdfhash = hash; + block->niv = qcrypto_cipher_get_iv_len(cipheralg, + ciphermode); + block->ivgen = qcrypto_ivgen_new(ivalg, + ivcipheralg, + ivhash, + masterkey, masterkeylen, + errp); + if (!block->ivgen) { + ret = -ENOTSUP; + goto fail; + } + + block->cipher = qcrypto_cipher_new(cipheralg, + ciphermode, + masterkey, masterkeylen, + errp); + if (!block->cipher) { + ret = -ENOTSUP; + goto fail; + } + } + + block->payload_offset = luks->header.payload_offset * + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE; + + g_free(masterkey); + g_free(password); + + return 0; + + fail: + g_free(masterkey); + qcrypto_cipher_free(block->cipher); + qcrypto_ivgen_free(block->ivgen); + g_free(luks); + g_free(password); + return ret; +} + + +static int +qcrypto_block_luks_uuid_gen(uint8_t *uuidstr, Error **errp) +{ +#ifdef CONFIG_UUID + uuid_t uuid; + uuid_generate(uuid); + uuid_unparse(uuid, (char *)uuidstr); + return 0; +#else + error_setg(errp, "Unable to generate uuids on this platform"); + return -1; +#endif +} + +static int +qcrypto_block_luks_create(QCryptoBlock *block, + QCryptoBlockCreateOptions *options, + QCryptoBlockInitFunc initfunc, + QCryptoBlockWriteFunc writefunc, + void *opaque, + Error **errp) +{ + QCryptoBlockLUKS *luks; + QCryptoBlockCreateOptionsLUKS luks_opts; + Error *local_err = NULL; + uint8_t *masterkey = NULL; + uint8_t *slotkey = NULL; + uint8_t *splitkey = NULL; + size_t splitkeylen = 0; + size_t i; + QCryptoCipher *cipher = NULL; + QCryptoIVGen *ivgen = NULL; + char *password; + const char *cipher_alg; + const char *cipher_mode; + const char *ivgen_alg; + const char *ivgen_hash_alg = NULL; + const char *hash_alg; + char *cipher_mode_spec = NULL; + QCryptoCipherAlgorithm ivcipheralg = 0; + + memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts)); + 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 (!options->u.luks.key_secret) { + error_setg(errp, "Parameter 'key-secret' is required for cipher"); + return -1; + } + password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp); + if (!password) { + return -1; + } + + luks = g_new0(QCryptoBlockLUKS, 1); + block->opaque = luks; + + 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; + if (qcrypto_block_luks_uuid_gen(luks->header.uuid, + errp) < 0) { + goto error; + } + + cipher_alg = qcrypto_block_luks_cipher_alg_lookup(luks_opts.cipher_alg, + errp); + if (!cipher_alg) { + goto error; + } + + cipher_mode = QCryptoCipherMode_lookup[luks_opts.cipher_mode]; + ivgen_alg = QCryptoIVGenAlgorithm_lookup[luks_opts.ivgen_alg]; + if (luks_opts.has_ivgen_hash_alg) { + ivgen_hash_alg = QCryptoHashAlgorithm_lookup[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_lookup[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) { + ivcipheralg = 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 { + ivcipheralg = 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.key_bytes = qcrypto_cipher_get_key_len(luks_opts.cipher_alg); + if (luks_opts.cipher_mode == QCRYPTO_CIPHER_MODE_XTS) { + luks->header.key_bytes *= 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.key_bytes); + if (qcrypto_random_bytes(masterkey, + luks->header.key_bytes, errp) < 0) { + goto error; + } + + + /* Setup the block device payload encryption objects */ + block->cipher = qcrypto_cipher_new(luks_opts.cipher_alg, + luks_opts.cipher_mode, + masterkey, luks->header.key_bytes, + errp); + if (!block->cipher) { + 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, + ivcipheralg, + luks_opts.ivgen_hash_alg, + masterkey, luks->header.key_bytes, + 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 + */ + luks->header.master_key_iterations = + qcrypto_pbkdf2_count_iters(luks_opts.hash_alg, + masterkey, luks->header.key_bytes, + luks->header.master_key_salt, + QCRYPTO_BLOCK_LUKS_SALT_LEN, + &local_err); + if (local_err) { + error_propagate(errp, local_err); + goto error; + } + + /* 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 */ + luks->header.master_key_iterations /= 8; + luks->header.master_key_iterations = MAX( + luks->header.master_key_iterations, + QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_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.key_bytes, + 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; + } + + + /* Although LUKS has multiple key slots, we're just going + * to use the first key slot */ + splitkeylen = luks->header.key_bytes * QCRYPTO_BLOCK_LUKS_STRIPES; + for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) { + luks->header.key_slots[i].active = i == 0 ? + QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED : + QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED; + luks->header.key_slots[i].stripes = QCRYPTO_BLOCK_LUKS_STRIPES; + + /* This calculation doesn't match that shown in the spec, + * but instead follows the cryptsetup implementation. + */ + luks->header.key_slots[i].key_offset = + (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET / + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) + + (ROUND_UP(((splitkeylen + (QCRYPTO_BLOCK_LUKS_SECTOR_SIZE - 1)) / + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE), + (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET / + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * i); + } + + if (qcrypto_random_bytes(luks->header.key_slots[0].salt, + QCRYPTO_BLOCK_LUKS_SALT_LEN, + errp) < 0) { + goto error; + } + + /* Again we determine how many iterations are required to + * hash the user password while consuming 1 second of compute + * time */ + luks->header.key_slots[0].iterations = + qcrypto_pbkdf2_count_iters(luks_opts.hash_alg, + (uint8_t *)password, strlen(password), + luks->header.key_slots[0].salt, + QCRYPTO_BLOCK_LUKS_SALT_LEN, + &local_err); + if (local_err) { + error_propagate(errp, local_err); + goto error; + } + /* Why /= 2 ? That matches cryptsetup, but there's no + * explanation why they chose /= 2... */ + luks->header.key_slots[0].iterations /= 2; + luks->header.key_slots[0].iterations = MAX( + luks->header.key_slots[0].iterations, + 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.key_bytes); + if (qcrypto_pbkdf2(luks_opts.hash_alg, + (uint8_t *)password, strlen(password), + luks->header.key_slots[0].salt, + QCRYPTO_BLOCK_LUKS_SALT_LEN, + luks->header.key_slots[0].iterations, + slotkey, luks->header.key_bytes, + errp) < 0) { + goto error; + } + + + /* Setup the encryption objects needed to encrypt the + * master key material + */ + cipher = qcrypto_cipher_new(luks_opts.cipher_alg, + luks_opts.cipher_mode, + slotkey, luks->header.key_bytes, + errp); + if (!cipher) { + goto error; + } + + ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg, + ivcipheralg, + luks_opts.ivgen_hash_alg, + slotkey, luks->header.key_bytes, + errp); + if (!ivgen) { + goto error; + } + + /* 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_opts.hash_alg, + luks->header.key_bytes, + luks->header.key_slots[0].stripes, + masterkey, + splitkey, + errp) < 0) { + goto error; + } + + /* Now we encrypt the split master key with the key generated + * from the user's password, before storing it */ + if (qcrypto_block_encrypt_helper(cipher, block->niv, ivgen, + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE, + 0, + splitkey, + splitkeylen, + errp) < 0) { + goto error; + } + + + /* 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 = + (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET / + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) + + (ROUND_UP(((splitkeylen + (QCRYPTO_BLOCK_LUKS_SECTOR_SIZE - 1)) / + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE), + (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET / + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * + QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS); + + block->payload_offset = luks->header.payload_offset * + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE; + + /* Reserve header space to match payload offset */ + initfunc(block, block->payload_offset, &local_err, opaque); + if (local_err) { + error_propagate(errp, local_err); + goto error; + } + + /* Everything on disk uses Big Endian, so flip header fields + * before writing them */ + cpu_to_be16s(&luks->header.version); + cpu_to_be32s(&luks->header.payload_offset); + cpu_to_be32s(&luks->header.key_bytes); + cpu_to_be32s(&luks->header.master_key_iterations); + + for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) { + cpu_to_be32s(&luks->header.key_slots[i].active); + cpu_to_be32s(&luks->header.key_slots[i].iterations); + cpu_to_be32s(&luks->header.key_slots[i].key_offset); + cpu_to_be32s(&luks->header.key_slots[i].stripes); + } + + + /* Write out the partition header and key slot headers */ + writefunc(block, 0, + (const uint8_t *)&luks->header, + sizeof(luks->header), + &local_err, + opaque); + + /* Delay checking local_err until we've byte-swapped */ + + /* Byte swap the header back to native, in case we need + * to read it again later */ + be16_to_cpus(&luks->header.version); + be32_to_cpus(&luks->header.payload_offset); + be32_to_cpus(&luks->header.key_bytes); + 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); + be32_to_cpus(&luks->header.key_slots[i].stripes); + } + + if (local_err) { + error_propagate(errp, local_err); + goto error; + } + + /* Write out the master key material, starting at the + * sector immediately following the partition header. */ + if (writefunc(block, + luks->header.key_slots[0].key_offset * + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE, + splitkey, splitkeylen, + errp, + opaque) != splitkeylen) { + goto error; + } + + memset(masterkey, 0, luks->header.key_bytes); + g_free(masterkey); + memset(slotkey, 0, luks->header.key_bytes); + g_free(slotkey); + g_free(splitkey); + g_free(password); + g_free(cipher_mode_spec); + + qcrypto_ivgen_free(ivgen); + qcrypto_cipher_free(cipher); + + return 0; + + error: + if (masterkey) { + memset(masterkey, 0, luks->header.key_bytes); + } + g_free(masterkey); + if (slotkey) { + memset(slotkey, 0, luks->header.key_bytes); + } + g_free(slotkey); + g_free(splitkey); + g_free(password); + g_free(cipher_mode_spec); + + qcrypto_ivgen_free(ivgen); + qcrypto_cipher_free(cipher); + + g_free(luks); + return -1; +} + + +static void qcrypto_block_luks_cleanup(QCryptoBlock *block) +{ + g_free(block->opaque); +} + + +static int +qcrypto_block_luks_decrypt(QCryptoBlock *block, + uint64_t startsector, + uint8_t *buf, + size_t len, + Error **errp) +{ + return qcrypto_block_decrypt_helper(block->cipher, + block->niv, block->ivgen, + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE, + startsector, buf, len, errp); +} + + +static int +qcrypto_block_luks_encrypt(QCryptoBlock *block, + uint64_t startsector, + uint8_t *buf, + size_t len, + Error **errp) +{ + return qcrypto_block_encrypt_helper(block->cipher, + block->niv, block->ivgen, + QCRYPTO_BLOCK_LUKS_SECTOR_SIZE, + startsector, buf, len, errp); +} + + +const QCryptoBlockDriver qcrypto_block_driver_luks = { + .open = qcrypto_block_luks_open, + .create = qcrypto_block_luks_create, + .cleanup = qcrypto_block_luks_cleanup, + .decrypt = qcrypto_block_luks_decrypt, + .encrypt = qcrypto_block_luks_encrypt, + .has_format = qcrypto_block_luks_has_format, +}; |