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/*
Unix SMB/CIFS implementation.
SMB2 signing
Copyright (C) Stefan Metzmacher 2009
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "system/filesys.h"
#include "../libcli/smb/smb_common.h"
#include "../lib/crypto/crypto.h"
NTSTATUS smb2_signing_sign_pdu(DATA_BLOB signing_key,
enum protocol_types protocol,
struct iovec *vector,
int count)
{
uint8_t *hdr;
uint64_t session_id;
uint8_t res[16];
int i;
if (count < 2) {
return NT_STATUS_INVALID_PARAMETER;
}
if (vector[0].iov_len != SMB2_HDR_BODY) {
return NT_STATUS_INVALID_PARAMETER;
}
hdr = (uint8_t *)vector[0].iov_base;
session_id = BVAL(hdr, SMB2_HDR_SESSION_ID);
if (session_id == 0) {
/*
* do not sign messages with a zero session_id.
* See MS-SMB2 3.2.4.1.1
*/
return NT_STATUS_OK;
}
if (signing_key.length == 0) {
DEBUG(2,("Wrong session key length %u for SMB2 signing\n",
(unsigned)signing_key.length));
return NT_STATUS_ACCESS_DENIED;
}
memset(hdr + SMB2_HDR_SIGNATURE, 0, 16);
SIVAL(hdr, SMB2_HDR_FLAGS, IVAL(hdr, SMB2_HDR_FLAGS) | SMB2_HDR_FLAG_SIGNED);
if (protocol >= PROTOCOL_SMB2_24) {
struct aes_cmac_128_context ctx;
uint8_t key[AES_BLOCK_SIZE];
ZERO_STRUCT(key);
memcpy(key, signing_key.data, MIN(signing_key.length, 16));
aes_cmac_128_init(&ctx, key);
for (i=0; i < count; i++) {
aes_cmac_128_update(&ctx,
(const uint8_t *)vector[i].iov_base,
vector[i].iov_len);
}
aes_cmac_128_final(&ctx, res);
} else {
struct HMACSHA256Context m;
uint8_t digest[SHA256_DIGEST_LENGTH];
ZERO_STRUCT(m);
hmac_sha256_init(signing_key.data, MIN(signing_key.length, 16), &m);
for (i=0; i < count; i++) {
hmac_sha256_update((const uint8_t *)vector[i].iov_base,
vector[i].iov_len, &m);
}
hmac_sha256_final(digest, &m);
memcpy(res, digest, 16);
}
DEBUG(5,("signed SMB2 message\n"));
memcpy(hdr + SMB2_HDR_SIGNATURE, res, 16);
return NT_STATUS_OK;
}
NTSTATUS smb2_signing_check_pdu(DATA_BLOB signing_key,
enum protocol_types protocol,
const struct iovec *vector,
int count)
{
const uint8_t *hdr;
const uint8_t *sig;
uint64_t session_id;
uint8_t res[16];
static const uint8_t zero_sig[16] = { 0, };
int i;
if (count < 2) {
return NT_STATUS_INVALID_PARAMETER;
}
if (vector[0].iov_len != SMB2_HDR_BODY) {
return NT_STATUS_INVALID_PARAMETER;
}
hdr = (const uint8_t *)vector[0].iov_base;
session_id = BVAL(hdr, SMB2_HDR_SESSION_ID);
if (session_id == 0) {
/*
* do not sign messages with a zero session_id.
* See MS-SMB2 3.2.4.1.1
*/
return NT_STATUS_OK;
}
if (signing_key.length == 0) {
/* we don't have the session key yet */
return NT_STATUS_OK;
}
sig = hdr+SMB2_HDR_SIGNATURE;
if (protocol >= PROTOCOL_SMB2_24) {
struct aes_cmac_128_context ctx;
uint8_t key[AES_BLOCK_SIZE];
ZERO_STRUCT(key);
memcpy(key, signing_key.data, MIN(signing_key.length, 16));
aes_cmac_128_init(&ctx, key);
aes_cmac_128_update(&ctx, hdr, SMB2_HDR_SIGNATURE);
aes_cmac_128_update(&ctx, zero_sig, 16);
for (i=1; i < count; i++) {
aes_cmac_128_update(&ctx,
(const uint8_t *)vector[i].iov_base,
vector[i].iov_len);
}
aes_cmac_128_final(&ctx, res);
} else {
struct HMACSHA256Context m;
uint8_t digest[SHA256_DIGEST_LENGTH];
ZERO_STRUCT(m);
hmac_sha256_init(signing_key.data, MIN(signing_key.length, 16), &m);
hmac_sha256_update(hdr, SMB2_HDR_SIGNATURE, &m);
hmac_sha256_update(zero_sig, 16, &m);
for (i=1; i < count; i++) {
hmac_sha256_update((const uint8_t *)vector[i].iov_base,
vector[i].iov_len, &m);
}
hmac_sha256_final(digest, &m);
memcpy(res, digest, 16);
}
if (memcmp(res, sig, 16) != 0) {
DEBUG(0,("Bad SMB2 signature for message\n"));
dump_data(0, sig, 16);
dump_data(0, res, 16);
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}
void smb2_key_derivation(const uint8_t *KI, size_t KI_len,
const uint8_t *Label, size_t Label_len,
const uint8_t *Context, size_t Context_len,
uint8_t KO[16])
{
struct HMACSHA256Context ctx;
uint8_t buf[4];
static const uint8_t zero = 0;
uint8_t digest[SHA256_DIGEST_LENGTH];
uint32_t i = 1;
uint32_t L = 128;
/*
* a simplified version of
* "NIST Special Publication 800-108" section 5.1
* using hmac-sha256.
*/
hmac_sha256_init(KI, KI_len, &ctx);
RSIVAL(buf, 0, i);
hmac_sha256_update(buf, sizeof(buf), &ctx);
hmac_sha256_update(Label, Label_len, &ctx);
hmac_sha256_update(&zero, 1, &ctx);
hmac_sha256_update(Context, Context_len, &ctx);
RSIVAL(buf, 0, L);
hmac_sha256_update(buf, sizeof(buf), &ctx);
hmac_sha256_final(digest, &ctx);
memcpy(KO, digest, 16);
}
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