/*
* zcrypt_key_lookup
*
* This function looks up the key we need based on the bookmark.
* It returns a reference to the key that the caller should NOT free.
* The caller should use zcrypt_key_hold/release()
* On failure it returns NULL;
*/
zcrypt_key_t *
zcrypt_key_lookup(spa_t *spa, uint64_t objset, uint64_t txg)
{
zcrypt_keystore_node_t *skn;
zcrypt_keychain_node_t *dkn;
crypto_mechanism_t mech = { 0 };
zcrypt_key_t *key;
#if _KERNEL
printk("zcrypt_key_lookup enter\n");
#endif
skn = zcrypt_keystore_find_node(spa, objset, B_FALSE);
if (skn == NULL)
return (NULL);
/* ZIL writes use txg 0 but we want the latest key */
if (txg == 0)
txg = -1UL;
mutex_enter(&skn->skn_lock);
dkn = zcrypt_keychain_find(skn->skn_keychain, txg);
if (dkn == NULL) {
mutex_exit(&skn->skn_lock);
return (NULL);
}
key = dkn->dkn_key;
if (key != NULL && !key->zk_ctx_tmpl_valid) {
mech.cm_type = crypto_mech2id(
zio_crypt_table[key->zk_crypt].ci_mechname);
if (crypto_create_ctx_template(&mech, &key->zk_key,
&key->zk_ctx_tmpl, KM_SLEEP) == CRYPTO_SUCCESS)
key->zk_ctx_tmpl_valid = B_TRUE;
}
if (key != NULL && !key->zk_mac_ctx_tmpl_valid) {
mech.cm_type = crypto_mech2id(SUN_CKM_SHA256_HMAC_GENERAL);
if (crypto_create_ctx_template(&mech, &key->zk_mackey,
&key->zk_mac_ctx_tmpl, KM_SLEEP) == CRYPTO_SUCCESS)
key->zk_mac_ctx_tmpl_valid = B_TRUE;
}
mutex_exit(&skn->skn_lock);
#if _KERNEL
printk("zcrypt_key_lookup exit: key %p\n", key);
#endif
return (key);
}
static int
pbkdf2(uint8_t *passphrase, size_t passphraselen, uint8_t *salt,
size_t saltlen, uint64_t iterations, uint8_t *output,
size_t outputlen)
{
int ret;
uint64_t iter;
uint32_t blockptr, i;
uint16_t hmac_key_len;
uint8_t *hmac_key;
uint8_t block[SHA1_DIGEST_LEN * 2];
uint8_t *hmacresult = block + SHA1_DIGEST_LEN;
crypto_mechanism_t mech;
crypto_key_t key;
crypto_data_t in_data, out_data;
crypto_ctx_template_t tmpl = NULL;
/* initialize output */
memset(output, 0, outputlen);
/* initialize icp for use */
thread_init();
icp_init();
/* HMAC key size is max(sizeof(uint32_t) + salt len, sha 256 len) */
if (saltlen > SHA1_DIGEST_LEN) {
hmac_key_len = saltlen + sizeof (uint32_t);
} else {
hmac_key_len = SHA1_DIGEST_LEN;
}
hmac_key = calloc(hmac_key_len, 1);
if (!hmac_key) {
ret = ENOMEM;
goto error;
}
/* initialize sha 256 hmac mechanism */
mech.cm_type = crypto_mech2id(SUN_CKM_SHA1_HMAC);
mech.cm_param = NULL;
mech.cm_param_len = 0;
/* initialize passphrase as a crypto key */
key.ck_format = CRYPTO_KEY_RAW;
key.ck_length = CRYPTO_BYTES2BITS(passphraselen);
key.ck_data = passphrase;
/*
* initialize crypto data for the input data. length will change
* after the first iteration, so we will initialize it in the loop.
*/
in_data.cd_format = CRYPTO_DATA_RAW;
in_data.cd_offset = 0;
in_data.cd_raw.iov_base = (char *)hmac_key;
/* initialize crypto data for the output data */
out_data.cd_format = CRYPTO_DATA_RAW;
out_data.cd_offset = 0;
out_data.cd_length = SHA1_DIGEST_LEN;
out_data.cd_raw.iov_base = (char *)hmacresult;
out_data.cd_raw.iov_len = out_data.cd_length;
/* initialize the context template */
ret = crypto_create_ctx_template(&mech, &key, &tmpl, KM_SLEEP);
if (ret != CRYPTO_SUCCESS) {
ret = EIO;
goto error;
}
/* main loop */
for (blockptr = 0; blockptr < outputlen; blockptr += SHA1_DIGEST_LEN) {
/*
* for the first iteration, the HMAC key is the user-provided
* salt concatenated with the block index (1-indexed)
*/
i = htobe32(1 + (blockptr / SHA1_DIGEST_LEN));
memmove(hmac_key, salt, saltlen);
memmove(hmac_key + saltlen, (uint8_t *)(&i), sizeof (uint32_t));
/* block initializes to zeroes (no XOR) */
memset(block, 0, SHA1_DIGEST_LEN);
for (iter = 0; iter < iterations; iter++) {
if (iter > 0) {
in_data.cd_length = SHA1_DIGEST_LEN;
in_data.cd_raw.iov_len = in_data.cd_length;
} else {
in_data.cd_length = saltlen + sizeof (uint32_t);
in_data.cd_raw.iov_len = in_data.cd_length;
}
ret = crypto_mac(&mech, &in_data, &key, tmpl,
&out_data, NULL);
if (ret != CRYPTO_SUCCESS) {
ret = EIO;
goto error;
}
/* HMAC key now becomes the output of this iteration */
memmove(hmac_key, hmacresult, SHA1_DIGEST_LEN);
/* XOR this iteration's result with the current block */
for (i = 0; i < SHA1_DIGEST_LEN; i++) {
block[i] ^= hmacresult[i];
}
}
/*
* compute length of this block, make sure we don't write
* beyond the end of the output, truncating if necessary
*/
if (blockptr + SHA1_DIGEST_LEN > outputlen) {
memmove(output + blockptr, block, outputlen - blockptr);
} else {
memmove(output + blockptr, block, SHA1_DIGEST_LEN);
}
}
crypto_destroy_ctx_template(tmpl);
free(hmac_key);
icp_fini();
thread_fini();
return (0);
error:
crypto_destroy_ctx_template(tmpl);
if (hmac_key != NULL)
free(hmac_key);
icp_fini();
thread_fini();
return (ret);
}