qcrypto-luks: extract store key function
This function will be used later to store new keys to the luks metadata Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Maxim Levitsky
Daniel P. Berrangé
parent
9fa9c1c28f
commit
3994a7c909
@ -623,6 +623,176 @@ qcrypto_block_luks_parse_header(QCryptoBlockLUKS *luks, Error **errp)
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return 0;
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}
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/*
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* Given a key slot, user password, and the master key,
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* will store the encrypted master key there, and update the
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* in-memory header. User must then write the in-memory header
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*
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* Returns:
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* 0 if the keyslot was written successfully
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* with the provided password
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* -1 if a fatal error occurred while storing the key
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*/
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static int
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qcrypto_block_luks_store_key(QCryptoBlock *block,
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unsigned int slot_idx,
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const char *password,
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uint8_t *masterkey,
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uint64_t iter_time,
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QCryptoBlockWriteFunc writefunc,
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void *opaque,
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Error **errp)
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{
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QCryptoBlockLUKS *luks = block->opaque;
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QCryptoBlockLUKSKeySlot *slot = &luks->header.key_slots[slot_idx];
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g_autofree uint8_t *splitkey = NULL;
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size_t splitkeylen;
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g_autofree uint8_t *slotkey = NULL;
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g_autoptr(QCryptoCipher) cipher = NULL;
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g_autoptr(QCryptoIVGen) ivgen = NULL;
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Error *local_err = NULL;
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uint64_t iters;
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int ret = -1;
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if (qcrypto_random_bytes(slot->salt,
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QCRYPTO_BLOCK_LUKS_SALT_LEN,
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errp) < 0) {
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goto cleanup;
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}
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splitkeylen = luks->header.master_key_len * slot->stripes;
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/*
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* Determine how many iterations are required to
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* hash the user password while consuming 1 second of compute
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* time
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*/
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iters = qcrypto_pbkdf2_count_iters(luks->hash_alg,
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(uint8_t *)password, strlen(password),
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slot->salt,
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QCRYPTO_BLOCK_LUKS_SALT_LEN,
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luks->header.master_key_len,
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&local_err);
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if (local_err) {
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error_propagate(errp, local_err);
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goto cleanup;
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}
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if (iters > (ULLONG_MAX / iter_time)) {
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error_setg_errno(errp, ERANGE,
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"PBKDF iterations %llu too large to scale",
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(unsigned long long)iters);
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goto cleanup;
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}
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/* iter_time was in millis, but count_iters reported for secs */
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iters = iters * iter_time / 1000;
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if (iters > UINT32_MAX) {
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error_setg_errno(errp, ERANGE,
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"PBKDF iterations %llu larger than %u",
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(unsigned long long)iters, UINT32_MAX);
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goto cleanup;
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}
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slot->iterations =
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MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
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/*
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* Generate a key that we'll use to encrypt the master
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* key, from the user's password
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*/
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slotkey = g_new0(uint8_t, luks->header.master_key_len);
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if (qcrypto_pbkdf2(luks->hash_alg,
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(uint8_t *)password, strlen(password),
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slot->salt,
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QCRYPTO_BLOCK_LUKS_SALT_LEN,
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slot->iterations,
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slotkey, luks->header.master_key_len,
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errp) < 0) {
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goto cleanup;
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}
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/*
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* Setup the encryption objects needed to encrypt the
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* master key material
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*/
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cipher = qcrypto_cipher_new(luks->cipher_alg,
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luks->cipher_mode,
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slotkey, luks->header.master_key_len,
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errp);
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if (!cipher) {
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goto cleanup;
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}
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ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
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luks->ivgen_cipher_alg,
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luks->ivgen_hash_alg,
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slotkey, luks->header.master_key_len,
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errp);
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if (!ivgen) {
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goto cleanup;
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}
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/*
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* Before storing the master key, we need to vastly
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* increase its size, as protection against forensic
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* disk data recovery
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*/
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splitkey = g_new0(uint8_t, splitkeylen);
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if (qcrypto_afsplit_encode(luks->hash_alg,
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luks->header.master_key_len,
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slot->stripes,
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masterkey,
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splitkey,
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errp) < 0) {
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goto cleanup;
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}
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/*
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* Now we encrypt the split master key with the key generated
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* from the user's password, before storing it
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*/
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if (qcrypto_block_cipher_encrypt_helper(cipher, block->niv, ivgen,
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QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
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0,
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splitkey,
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splitkeylen,
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errp) < 0) {
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goto cleanup;
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}
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/* Write out the slot's master key material. */
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if (writefunc(block,
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slot->key_offset_sector *
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QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
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splitkey, splitkeylen,
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opaque,
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errp) != splitkeylen) {
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goto cleanup;
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}
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slot->active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
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if (qcrypto_block_luks_store_header(block, writefunc, opaque, errp) < 0) {
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goto cleanup;
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}
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ret = 0;
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cleanup:
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if (slotkey) {
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memset(slotkey, 0, luks->header.master_key_len);
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}
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if (splitkey) {
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memset(splitkey, 0, splitkeylen);
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}
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return ret;
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}
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/*
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* Given a key slot, and user password, this will attempt to unlock
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* the master encryption key from the key slot.
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@ -944,12 +1114,8 @@ qcrypto_block_luks_create(QCryptoBlock *block,
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QCryptoBlockCreateOptionsLUKS luks_opts;
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Error *local_err = NULL;
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g_autofree uint8_t *masterkey = NULL;
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g_autofree uint8_t *slotkey = NULL;
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g_autofree uint8_t *splitkey = NULL;
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size_t splitkeylen = 0;
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size_t i;
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g_autoptr(QCryptoCipher) cipher = NULL;
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g_autoptr(QCryptoIVGen) ivgen = NULL;
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g_autofree char *password = NULL;
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const char *cipher_alg;
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const char *cipher_mode;
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@ -1172,9 +1338,7 @@ qcrypto_block_luks_create(QCryptoBlock *block,
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* to use the first key slot */
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splitkeylen = luks->header.master_key_len * QCRYPTO_BLOCK_LUKS_STRIPES;
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for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
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luks->header.key_slots[i].active = i == 0 ?
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QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED :
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QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
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luks->header.key_slots[i].active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
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luks->header.key_slots[i].stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
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/* This calculation doesn't match that shown in the spec,
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@ -1188,107 +1352,6 @@ qcrypto_block_luks_create(QCryptoBlock *block,
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QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * i);
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}
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if (qcrypto_random_bytes(luks->header.key_slots[0].salt,
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QCRYPTO_BLOCK_LUKS_SALT_LEN,
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errp) < 0) {
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goto error;
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}
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/* Again we determine how many iterations are required to
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* hash the user password while consuming 1 second of compute
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* time */
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iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
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(uint8_t *)password, strlen(password),
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luks->header.key_slots[0].salt,
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QCRYPTO_BLOCK_LUKS_SALT_LEN,
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luks->header.master_key_len,
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&local_err);
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if (local_err) {
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error_propagate(errp, local_err);
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goto error;
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}
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if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
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error_setg_errno(errp, ERANGE,
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"PBKDF iterations %llu too large to scale",
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(unsigned long long)iters);
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goto error;
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}
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/* iter_time was in millis, but count_iters reported for secs */
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iters = iters * luks_opts.iter_time / 1000;
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if (iters > UINT32_MAX) {
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error_setg_errno(errp, ERANGE,
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"PBKDF iterations %llu larger than %u",
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(unsigned long long)iters, UINT32_MAX);
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goto error;
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}
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luks->header.key_slots[0].iterations =
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MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
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/* Generate a key that we'll use to encrypt the master
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* key, from the user's password
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*/
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slotkey = g_new0(uint8_t, luks->header.master_key_len);
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if (qcrypto_pbkdf2(luks_opts.hash_alg,
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(uint8_t *)password, strlen(password),
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luks->header.key_slots[0].salt,
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QCRYPTO_BLOCK_LUKS_SALT_LEN,
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luks->header.key_slots[0].iterations,
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slotkey, luks->header.master_key_len,
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errp) < 0) {
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goto error;
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}
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/* Setup the encryption objects needed to encrypt the
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* master key material
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*/
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cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
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luks_opts.cipher_mode,
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slotkey, luks->header.master_key_len,
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errp);
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if (!cipher) {
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goto error;
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}
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ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
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luks->ivgen_cipher_alg,
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luks_opts.ivgen_hash_alg,
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slotkey, luks->header.master_key_len,
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errp);
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if (!ivgen) {
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goto error;
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}
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/* Before storing the master key, we need to vastly
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* increase its size, as protection against forensic
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* disk data recovery */
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splitkey = g_new0(uint8_t, splitkeylen);
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if (qcrypto_afsplit_encode(luks_opts.hash_alg,
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luks->header.master_key_len,
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luks->header.key_slots[0].stripes,
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masterkey,
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splitkey,
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errp) < 0) {
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goto error;
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}
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/* Now we encrypt the split master key with the key generated
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* from the user's password, before storing it */
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if (qcrypto_block_cipher_encrypt_helper(cipher, block->niv, ivgen,
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QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
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0,
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splitkey,
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splitkeylen,
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errp) < 0) {
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goto error;
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}
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/* The total size of the LUKS headers is the partition header + key
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* slot headers, rounded up to the nearest sector, combined with
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@ -1313,23 +1376,21 @@ qcrypto_block_luks_create(QCryptoBlock *block,
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goto error;
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}
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if (qcrypto_block_luks_store_header(block, writefunc, opaque, errp) < 0) {
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goto error;
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}
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/* Write out the master key material, starting at the
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* sector immediately following the partition header. */
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if (writefunc(block,
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luks->header.key_slots[0].key_offset_sector *
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QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
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splitkey, splitkeylen,
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opaque,
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errp) != splitkeylen) {
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/* populate the slot 0 with the password encrypted master key*/
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/* This will also store the header */
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if (qcrypto_block_luks_store_key(block,
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0,
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password,
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masterkey,
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luks_opts.iter_time,
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writefunc,
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opaque,
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errp) < 0) {
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goto error;
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}
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memset(masterkey, 0, luks->header.master_key_len);
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memset(slotkey, 0, luks->header.master_key_len);
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return 0;
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@ -1337,9 +1398,6 @@ qcrypto_block_luks_create(QCryptoBlock *block,
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if (masterkey) {
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memset(masterkey, 0, luks->header.master_key_len);
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}
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if (slotkey) {
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memset(slotkey, 0, luks->header.master_key_len);
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}
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qcrypto_block_free_cipher(block);
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qcrypto_ivgen_free(block->ivgen);
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