/* Try to open a particular key slot */
static int LUKS_open_key(unsigned int keyIndex,
const char *password,
size_t passwordLen,
struct luks_phdr *hdr,
struct volume_key *vk,
struct crypt_device *ctx)
{
crypt_keyslot_info ki = LUKS_keyslot_info(hdr, keyIndex);
struct volume_key *derived_key;
char *AfKey;
size_t AFEKSize;
int r;
log_dbg("Trying to open key slot %d [%s].", keyIndex,
dbg_slot_state(ki));
if (ki < CRYPT_SLOT_ACTIVE)
return -ENOENT;
derived_key = crypt_alloc_volume_key(hdr->keyBytes, NULL);
if (!derived_key)
return -ENOMEM;
assert(vk->keylength == hdr->keyBytes);
AFEKSize = AF_split_sectors(vk->keylength, hdr->keyblock[keyIndex].stripes) * SECTOR_SIZE;
AfKey = crypt_safe_alloc(AFEKSize);
if (!AfKey) {
r = -ENOMEM;
goto out;
}
r = crypt_pbkdf("pbkdf2", hdr->hashSpec, password, passwordLen,
hdr->keyblock[keyIndex].passwordSalt, LUKS_SALTSIZE,
derived_key->key, hdr->keyBytes,
hdr->keyblock[keyIndex].passwordIterations);
if (r < 0)
goto out;
log_dbg("Reading key slot %d area.", keyIndex);
r = LUKS_decrypt_from_storage(AfKey,
AFEKSize,
hdr->cipherName, hdr->cipherMode,
derived_key,
hdr->keyblock[keyIndex].keyMaterialOffset,
ctx);
if (r < 0)
goto out;
r = AF_merge(AfKey,vk->key,vk->keylength,hdr->keyblock[keyIndex].stripes,hdr->hashSpec);
if (r < 0)
goto out;
r = LUKS_verify_volume_key(hdr, vk);
if (!r)
log_verbose(ctx, _("Key slot %d unlocked.\n"), keyIndex);
out:
crypt_safe_free(AfKey);
crypt_free_volume_key(derived_key);
return r;
}
/* Check that kernel supports requested cipher by decryption of one sector */
static int LUKS_check_cipher(struct luks_phdr *hdr, struct crypt_device *ctx)
{
int r;
struct volume_key *empty_key;
char buf[SECTOR_SIZE];
log_dbg("Checking if cipher %s-%s is usable.", hdr->cipherName, hdr->cipherMode);
empty_key = crypt_alloc_volume_key(hdr->keyBytes, NULL);
if (!empty_key)
return -ENOMEM;
r = LUKS_decrypt_from_storage(buf, sizeof(buf),
hdr->cipherName, hdr->cipherMode,
empty_key, 0, ctx);
crypt_free_volume_key(empty_key);
crypt_memzero(buf, sizeof(buf));
return r;
}
/* Check that kernel supports requested cipher by decryption of one sector */
int LUKS_check_cipher(struct crypt_device *ctx, size_t keylength, const char *cipher, const char *cipher_mode)
{
int r;
struct volume_key *empty_key;
char buf[SECTOR_SIZE];
log_dbg("Checking if cipher %s-%s is usable.", cipher, cipher_mode);
empty_key = crypt_alloc_volume_key(keylength, NULL);
if (!empty_key)
return -ENOMEM;
/* No need to get KEY quality random but it must avoid known weak keys. */
r = crypt_random_get(ctx, empty_key->key, empty_key->keylength, CRYPT_RND_NORMAL);
if (!r)
r = LUKS_decrypt_from_storage(buf, sizeof(buf), cipher, cipher_mode, empty_key, 0, ctx);
crypt_free_volume_key(empty_key);
crypt_memzero(buf, sizeof(buf));
return r;
}
int decryptFromStorage(
char *dst, size_t dstLength,
const char *cipher,
const char *cipher_mode,
const char *vkey, size_t vkLength,
unsigned int sector,
struct crypt_device *ctx)
{
struct volume_key* vk = malloc(sizeof(struct volume_key) + vkLength);
vk->keylength = vkLength;
memcpy(&vk->key, vkey, vkLength);
const int r = LUKS_decrypt_from_storage
(
dst, dstLength,
cipher, cipher_mode,
vk,
sector,
ctx
);
free(vk);
return r;
}
