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/*
Copyright (c) 2008-2013 Red Hat, Inc. <http://www.redhat.com>
This file is part of GlusterFS.
This file is licensed to you under your choice of the GNU Lesser
General Public License, version 3 or any later version (LGPLv3 or
later), or the GNU General Public License, version 2 (GPLv2), in all
cases as published by the Free Software Foundation.
*/
#include "defaults.h"
#include "crypt-common.h"
#include "crypt.h"
/* Key hierarchy
+----------------+
| MASTER_VOL_KEY |
+-------+--------+
|
|
+----------------+----------------+
| | |
| | |
+-------+------+ +-------+-------+ +------+--------+
| NMTD_VOL_KEY | | EMTD_FILE_KEY | | DATA_FILE_KEY |
+-------+------+ +---------------+ +---------------+
|
|
+-------+-------+
| NMTD_LINK_KEY |
+---------------+
*/
#if DEBUG_CRYPT
static void check_prf_iters(uint32_t num_iters)
{
if (num_iters == 0)
gf_log ("crypt", GF_LOG_DEBUG,
"bad number of prf iterations : %d", num_iters);
}
#else
#define check_prf_iters(num_iters) noop
#endif /* DEBUG_CRYPT */
unsigned char crypt_fake_oid[16] =
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
/*
* derive key in the counter mode using
* sha256-based HMAC as PRF, see
* NIST Special Publication 800-108, 5.1)
*/
#define PRF_OUTPUT_SIZE SHA256_DIGEST_LENGTH
static int32_t kderive_init(struct kderive_context *ctx,
const unsigned char *pkey, /* parent key */
uint32_t pkey_size, /* parent key size */
const unsigned char *idctx, /* id-context */
uint32_t idctx_size,
crypt_key_type type /* type of child key */)
{
unsigned char *pos;
uint32_t llen = strlen(crypt_keys[type].label);
/*
* Compoud the fixed input data for KDF:
* [i]_2 || Label || 0x00 || Id-Context || [L]_2),
* NIST SP 800-108, 5.1
*/
ctx->fid_len =
sizeof(uint32_t) +
llen +
1 +
idctx_size +
sizeof(uint32_t);
ctx->fid = GF_CALLOC(ctx->fid_len, 1, gf_crypt_mt_key);
if (!ctx->fid)
return ENOMEM;
ctx->out_len = round_up(crypt_keys[type].len >> 3,
PRF_OUTPUT_SIZE);
ctx->out = GF_CALLOC(ctx->out_len, 1, gf_crypt_mt_key);
if (!ctx->out) {
GF_FREE(ctx->fid);
return ENOMEM;
}
ctx->pkey = pkey;
ctx->pkey_len = pkey_size;
ctx->ckey_len = crypt_keys[type].len;
pos = ctx->fid;
/* counter will be set up in kderive_rfn() */
pos += sizeof(uint32_t);
memcpy(pos, crypt_keys[type].label, llen);
pos += llen;
/* set up zero octet */
*pos = 0;
pos += 1;
memcpy(pos, idctx, idctx_size);
pos += idctx_size;
*((uint32_t *)pos) = htobe32(ctx->ckey_len);
return 0;
}
static void kderive_update(struct kderive_context *ctx)
{
uint32_t i;
HMAC_CTX hctx;
unsigned char *pos = ctx->out;
uint32_t *p_iter = (uint32_t *)ctx->fid;
uint32_t num_iters = ctx->out_len / PRF_OUTPUT_SIZE;
check_prf_iters(num_iters);
HMAC_CTX_init(&hctx);
for (i = 0; i < num_iters; i++) {
/*
* update the iteration number in the fid
*/
*p_iter = htobe32(i);
HMAC_Init_ex(&hctx,
ctx->pkey, ctx->pkey_len >> 3,
EVP_sha256(),
NULL);
HMAC_Update(&hctx, ctx->fid, ctx->fid_len);
HMAC_Final(&hctx, pos, NULL);
pos += PRF_OUTPUT_SIZE;
}
HMAC_CTX_cleanup(&hctx);
}
static void kderive_final(struct kderive_context *ctx, unsigned char *child)
{
memcpy(child, ctx->out, ctx->ckey_len >> 3);
GF_FREE(ctx->fid);
GF_FREE(ctx->out);
memset(ctx, 0, sizeof(*ctx));
}
/*
* derive per-volume key for object ids aithentication
*/
int32_t get_nmtd_vol_key(struct master_cipher_info *master)
{
int32_t ret;
struct kderive_context ctx;
ret = kderive_init(&ctx,
master->m_key,
master_key_size(),
crypt_fake_oid, sizeof(uuid_t), NMTD_VOL_KEY);
if (ret)
return ret;
kderive_update(&ctx);
kderive_final(&ctx, master->m_nmtd_key);
return 0;
}
/*
* derive per-link key for aithentication of non-encrypted
* meta-data (nmtd)
*/
int32_t get_nmtd_link_key(loc_t *loc,
struct master_cipher_info *master,
unsigned char *result)
{
int32_t ret;
struct kderive_context ctx;
ret = kderive_init(&ctx,
master->m_nmtd_key,
nmtd_vol_key_size(),
(const unsigned char *)loc->path,
strlen(loc->path), NMTD_LINK_KEY);
if (ret)
return ret;
kderive_update(&ctx);
kderive_final(&ctx, result);
return 0;
}
/*
* derive per-file key for encryption and authentication
* of encrypted part of metadata (emtd)
*/
int32_t get_emtd_file_key(struct crypt_inode_info *info,
struct master_cipher_info *master,
unsigned char *result)
{
int32_t ret;
struct kderive_context ctx;
ret = kderive_init(&ctx,
master->m_key,
master_key_size(),
info->oid, sizeof(uuid_t), EMTD_FILE_KEY);
if (ret)
return ret;
kderive_update(&ctx);
kderive_final(&ctx, result);
return 0;
}
static int32_t data_key_type_by_size(uint32_t keysize, crypt_key_type *type)
{
int32_t ret = 0;
switch (keysize) {
case 256:
*type = DATA_FILE_KEY_256;
break;
case 512:
*type = DATA_FILE_KEY_512;
break;
default:
gf_log("crypt", GF_LOG_ERROR, "Unsupported data key size %d",
keysize);
ret = ENOTSUP;
break;
}
return ret;
}
/*
* derive per-file key for data encryption
*/
int32_t get_data_file_key(struct crypt_inode_info *info,
struct master_cipher_info *master,
uint32_t keysize,
unsigned char *key)
{
int32_t ret;
struct kderive_context ctx;
crypt_key_type type;
ret = data_key_type_by_size(keysize, &type);
if (ret)
return ret;
ret = kderive_init(&ctx,
master->m_key,
master_key_size(),
info->oid, sizeof(uuid_t), type);
if (ret)
return ret;
kderive_update(&ctx);
kderive_final(&ctx, key);
return 0;
}
/*
* NOTE: Don't change existing keys: it will break compatibility;
*/
struct crypt_key crypt_keys[LAST_KEY_TYPE] = {
[MASTER_VOL_KEY] =
{ .len = MASTER_VOL_KEY_SIZE << 3,
.label = "volume-master",
},
[NMTD_VOL_KEY] =
{ .len = NMTD_VOL_KEY_SIZE << 3,
.label = "volume-nmtd-key-generation"
},
[NMTD_LINK_KEY] =
{ .len = 128,
.label = "link-nmtd-authentication"
},
[EMTD_FILE_KEY] =
{ .len = 128,
.label = "file-emtd-encryption-and-auth"
},
[DATA_FILE_KEY_256] =
{ .len = 256,
.label = "file-data-encryption-256"
},
[DATA_FILE_KEY_512] =
{ .len = 512,
.label = "file-data-encryption-512"
}
};
/*
Local variables:
c-indentation-style: "K&R"
mode-name: "LC"
c-basic-offset: 8
tab-width: 8
fill-column: 80
scroll-step: 1
End:
*/
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