diff options
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/block-luks.c | 416 |
1 files changed, 412 insertions, 4 deletions
diff --git a/crypto/block-luks.c b/crypto/block-luks.c index 4861db810c..564caa1094 100644 --- a/crypto/block-luks.c +++ b/crypto/block-luks.c @@ -32,6 +32,7 @@ #include "qemu/uuid.h" #include "qemu/coroutine.h" +#include "qemu/bitmap.h" /* * Reference for the LUKS format implemented here is @@ -70,6 +71,9 @@ typedef struct QCryptoBlockLUKSKeySlot QCryptoBlockLUKSKeySlot; #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 }; @@ -219,6 +223,9 @@ struct QCryptoBlockLUKS { /* Hash algorithm used in pbkdf2 function */ QCryptoHashAlgorithm hash_alg; + + /* Name of the secret that was used to open the image */ + char *secret; }; @@ -720,7 +727,7 @@ qcrypto_block_luks_store_key(QCryptoBlock *block, Error **errp) { QCryptoBlockLUKS *luks = block->opaque; - QCryptoBlockLUKSKeySlot *slot = &luks->header.key_slots[slot_idx]; + QCryptoBlockLUKSKeySlot *slot; g_autofree uint8_t *splitkey = NULL; size_t splitkeylen; g_autofree uint8_t *slotkey = NULL; @@ -730,6 +737,8 @@ qcrypto_block_luks_store_key(QCryptoBlock *block, 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) { @@ -890,7 +899,7 @@ qcrypto_block_luks_load_key(QCryptoBlock *block, Error **errp) { QCryptoBlockLUKS *luks = block->opaque; - const QCryptoBlockLUKSKeySlot *slot = &luks->header.key_slots[slot_idx]; + const QCryptoBlockLUKSKeySlot *slot; g_autofree uint8_t *splitkey = NULL; size_t splitkeylen; g_autofree uint8_t *possiblekey = NULL; @@ -900,6 +909,8 @@ qcrypto_block_luks_load_key(QCryptoBlock *block, 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; } @@ -1069,6 +1080,126 @@ qcrypto_block_luks_find_key(QCryptoBlock *block, 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, @@ -1099,6 +1230,7 @@ qcrypto_block_luks_open(QCryptoBlock *block, 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; @@ -1164,6 +1296,7 @@ qcrypto_block_luks_open(QCryptoBlock *block, fail: qcrypto_block_free_cipher(block); qcrypto_ivgen_free(block->ivgen); + g_free(luks->secret); g_free(luks); return -1; } @@ -1204,7 +1337,7 @@ qcrypto_block_luks_create(QCryptoBlock *block, memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts)); if (!luks_opts.has_iter_time) { - luks_opts.iter_time = 2000; + 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; @@ -1244,6 +1377,8 @@ qcrypto_block_luks_create(QCryptoBlock *block, 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; @@ -1471,10 +1606,278 @@ qcrypto_block_luks_create(QCryptoBlock *block, 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, @@ -1523,7 +1926,11 @@ static int qcrypto_block_luks_get_info(QCryptoBlock *block, static void qcrypto_block_luks_cleanup(QCryptoBlock *block) { - g_free(block->opaque); + QCryptoBlockLUKS *luks = block->opaque; + if (luks) { + g_free(luks->secret); + g_free(luks); + } } @@ -1560,6 +1967,7 @@ qcrypto_block_luks_encrypt(QCryptoBlock *block, 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, |