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Code

libcli/auth: rewrite schannel sign/seal code to be more generic

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This prepares support for HMAC-SHA256/AES.

metze
This commit is contained in:
Stefan Metzmacher 2009-09-16 02:03:46 +02:00
parent 8f482ae663
commit 033ced60ac
5 changed files with 268 additions and 234 deletions
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21
libcli/auth/schannel_proto.h
View File

@ -23,20 +23,15 @@
#ifndef _LIBCLI_AUTH_SCHANNEL_PROTO_H__
#define _LIBCLI_AUTH_SCHANNEL_PROTO_H__
NTSTATUS schannel_unseal_packet(struct schannel_state *state,
NTSTATUS netsec_incoming_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
bool do_unseal,
uint8_t *data, size_t length,
const DATA_BLOB *sig);
NTSTATUS schannel_check_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
const uint8_t *data, size_t length,
const DATA_BLOB *sig);
NTSTATUS schannel_seal_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
uint8_t *data, size_t length,
DATA_BLOB *sig);
NTSTATUS schannel_sign_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
const uint8_t *data, size_t length,
DATA_BLOB *sig);
NTSTATUS netsec_outgoing_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
bool do_seal,
uint8_t *data, size_t length,
DATA_BLOB *sig);
#endif

301
libcli/auth/schannel_sign.c
View File

@ -24,58 +24,89 @@
#include "../libcli/auth/schannel.h"
#include "../lib/crypto/crypto.h"
#define NETSEC_SIGN_SIGNATURE { 0x77, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00 }
#define NETSEC_SEAL_SIGNATURE { 0x77, 0x00, 0x7a, 0x00, 0xff, 0xff, 0x00, 0x00 }
static void netsec_offset_and_sizes(struct schannel_state *state,
bool do_seal,
uint32_t *_min_sig_size,
uint32_t *_used_sig_size,
uint32_t *_checksum_length,
uint32_t *_confounder_ofs)
{
uint32_t min_sig_size = 24;
uint32_t used_sig_size = 32;
uint32_t checksum_length = 8;
uint32_t confounder_ofs = 24;
if (do_seal) {
min_sig_size += 8;
}
if (_min_sig_size) {
*_min_sig_size = min_sig_size;
}
if (_used_sig_size) {
*_used_sig_size = used_sig_size;
}
if (_checksum_length) {
*_checksum_length = checksum_length;
}
if (_confounder_ofs) {
*_confounder_ofs = confounder_ofs;
}
}
/*******************************************************************
Encode or Decode the sequence number (which is symmetric)
********************************************************************/
static void netsec_deal_with_seq_num(struct schannel_state *state,
const uint8_t packet_digest[8],
uint8_t seq_num[8])
static void netsec_do_seq_num(struct schannel_state *state,
const uint8_t *checksum,
uint32_t checksum_length,
uint8_t seq_num[8])
{
static const uint8_t zeros[4];
uint8_t sequence_key[16];
uint8_t digest1[16];
hmac_md5(state->creds->session_key, zeros, sizeof(zeros), digest1);
hmac_md5(digest1, packet_digest, 8, sequence_key);
hmac_md5(digest1, checksum, checksum_length, sequence_key);
arcfour_crypt(seq_num, sequence_key, 8);
state->seq_num++;
}
/*******************************************************************
Calculate the key with which to encode the data payload
********************************************************************/
static void netsec_get_sealing_key(const uint8_t session_key[16],
const uint8_t seq_num[8],
uint8_t sealing_key[16])
static void netsec_do_seal(struct schannel_state *state,
const uint8_t seq_num[8],
uint8_t confounder[8],
uint8_t *data, uint32_t length)
{
uint8_t sealing_key[16];
static const uint8_t zeros[4];
uint8_t digest2[16];
uint8_t sess_kf0[16];
int i;
for (i = 0; i < 16; i++) {
sess_kf0[i] = session_key[i] ^ 0xf0;
sess_kf0[i] = state->creds->session_key[i] ^ 0xf0;
}
hmac_md5(sess_kf0, zeros, 4, digest2);
hmac_md5(digest2, seq_num, 8, sealing_key);
}
arcfour_crypt(confounder, sealing_key, 8);
arcfour_crypt(data, sealing_key, length);
}
/*******************************************************************
Create a digest over the entire packet (including the data), and
MD5 it with the session key.
********************************************************************/
static void schannel_digest(const uint8_t sess_key[16],
const uint8_t netsec_sig[8],
const uint8_t *confounder,
const uint8_t *data, size_t data_len,
uint8_t digest_final[16])
static void netsec_do_sign(struct schannel_state *state,
const uint8_t *confounder,
const uint8_t *data, size_t data_len,
uint8_t header[8],
uint8_t *checksum)
{
uint8_t packet_digest[16];
static const uint8_t zeros[4];
@ -83,57 +114,88 @@ static void schannel_digest(const uint8_t sess_key[16],
MD5Init(&ctx);
MD5Update(&ctx, zeros, 4);
MD5Update(&ctx, netsec_sig, 8);
if (confounder) {
SSVAL(header, 0, NL_SIGN_HMAC_MD5);
SSVAL(header, 2, NL_SEAL_RC4);
SSVAL(header, 4, 0xFFFF);
SSVAL(header, 6, 0x0000);
MD5Update(&ctx, header, 8);
MD5Update(&ctx, confounder, 8);
} else {
SSVAL(header, 0, NL_SIGN_HMAC_MD5);
SSVAL(header, 2, NL_SEAL_NONE);
SSVAL(header, 4, 0xFFFF);
SSVAL(header, 6, 0x0000);
MD5Update(&ctx, header, 8);
}
MD5Update(&ctx, data, data_len);
MD5Final(packet_digest, &ctx);
hmac_md5(sess_key, packet_digest, sizeof(packet_digest), digest_final);
hmac_md5(state->creds->session_key,
packet_digest, sizeof(packet_digest),
checksum);
}
/*
unseal a packet
*/
NTSTATUS schannel_unseal_packet(struct schannel_state *state,
NTSTATUS netsec_incoming_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
bool do_unseal,
uint8_t *data, size_t length,
const DATA_BLOB *sig)
{
uint8_t digest_final[16];
uint8_t confounder[8];
uint32_t min_sig_size = 0;
uint8_t header[8];
uint8_t checksum[32];
uint32_t checksum_length = sizeof(checksum_length);
uint8_t _confounder[8];
uint8_t *confounder = NULL;
uint32_t confounder_ofs = 0;
uint8_t seq_num[8];
uint8_t sealing_key[16];
static const uint8_t netsec_sig[8] = NETSEC_SEAL_SIGNATURE;
int ret;
if (sig->length != 32) {
netsec_offset_and_sizes(state,
do_unseal,
&min_sig_size,
NULL,
&checksum_length,
&confounder_ofs);
if (sig->length < min_sig_size) {
return NT_STATUS_ACCESS_DENIED;
}
memcpy(confounder, sig->data+24, 8);
if (do_unseal) {
confounder = _confounder;
memcpy(confounder, sig->data+confounder_ofs, 8);
} else {
confounder = NULL;
}
RSIVAL(seq_num, 0, state->seq_num);
SIVAL(seq_num, 4, state->initiator?0:0x80);
netsec_get_sealing_key(state->creds->session_key, seq_num, sealing_key);
arcfour_crypt(confounder, sealing_key, 8);
arcfour_crypt(data, sealing_key, length);
if (do_unseal) {
netsec_do_seal(state, seq_num,
confounder,
data, length);
}
schannel_digest(state->creds->session_key,
netsec_sig, confounder,
data, length, digest_final);
netsec_do_sign(state, confounder,
data, length,
header, checksum);
if (memcmp(digest_final, sig->data+16, 8) != 0) {
dump_data_pw("calc digest:", digest_final, 8);
dump_data_pw("wire digest:", sig->data+16, 8);
ret = memcmp(checksum, sig->data+16, checksum_length);
if (ret != 0) {
dump_data_pw("calc digest:", checksum, checksum_length);
dump_data_pw("wire digest:", sig->data+16, checksum_length);
return NT_STATUS_ACCESS_DENIED;
}
netsec_deal_with_seq_num(state, digest_final, seq_num);
netsec_do_seq_num(state, checksum, checksum_length, seq_num);
if (memcmp(seq_num, sig->data+8, 8) != 0) {
ret = memcmp(seq_num, sig->data+8, 8);
if (ret != 0) {
dump_data_pw("calc seq num:", seq_num, 8);
dump_data_pw("wire seq num:", sig->data+8, 8);
return NT_STATUS_ACCESS_DENIED;
@ -142,128 +204,65 @@ NTSTATUS schannel_unseal_packet(struct schannel_state *state,
return NT_STATUS_OK;
}
/*
check the signature on a packet
*/
NTSTATUS schannel_check_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
const uint8_t *data, size_t length,
const DATA_BLOB *sig)
NTSTATUS netsec_outgoing_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
bool do_seal,
uint8_t *data, size_t length,
DATA_BLOB *sig)
{
uint8_t digest_final[16];
uint32_t min_sig_size = 0;
uint32_t used_sig_size = 0;
uint8_t header[8];
uint8_t checksum[32];
uint32_t checksum_length = sizeof(checksum_length);
uint8_t _confounder[8];
uint8_t *confounder = NULL;
uint32_t confounder_ofs = 0;
uint8_t seq_num[8];
static const uint8_t netsec_sig[8] = NETSEC_SIGN_SIGNATURE;
/* w2k sends just 24 bytes and skip the confounder */
if (sig->length != 32 && sig->length != 24) {
return NT_STATUS_ACCESS_DENIED;
}
RSIVAL(seq_num, 0, state->seq_num);
SIVAL(seq_num, 4, state->initiator?0:0x80);
dump_data_pw("seq_num:\n", seq_num, 8);
dump_data_pw("sess_key:\n", state->creds->session_key, 16);
schannel_digest(state->creds->session_key,
netsec_sig, NULL,
data, length, digest_final);
netsec_deal_with_seq_num(state, digest_final, seq_num);
if (memcmp(seq_num, sig->data+8, 8) != 0) {
dump_data_pw("calc seq num:", seq_num, 8);
dump_data_pw("wire seq num:", sig->data+8, 8);
return NT_STATUS_ACCESS_DENIED;
}
if (memcmp(digest_final, sig->data+16, 8) != 0) {
dump_data_pw("calc digest:", digest_final, 8);
dump_data_pw("wire digest:", sig->data+16, 8);
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}
/*
seal a packet
*/
NTSTATUS schannel_seal_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
uint8_t *data, size_t length,
DATA_BLOB *sig)
{
uint8_t digest_final[16];
uint8_t confounder[8];
uint8_t seq_num[8];
uint8_t sealing_key[16];
static const uint8_t netsec_sig[8] = NETSEC_SEAL_SIGNATURE;
generate_random_buffer(confounder, 8);
netsec_offset_and_sizes(state,
do_seal,
&min_sig_size,
&used_sig_size,
&checksum_length,
&confounder_ofs);
RSIVAL(seq_num, 0, state->seq_num);
SIVAL(seq_num, 4, state->initiator?0x80:0);
schannel_digest(state->creds->session_key,
netsec_sig, confounder,
data, length, digest_final);
if (do_seal) {
confounder = _confounder;
generate_random_buffer(confounder, 8);
} else {
confounder = NULL;
}
netsec_get_sealing_key(state->creds->session_key, seq_num, sealing_key);
arcfour_crypt(confounder, sealing_key, 8);
arcfour_crypt(data, sealing_key, length);
netsec_do_sign(state, confounder,
data, length,
header, checksum);
netsec_deal_with_seq_num(state, digest_final, seq_num);
if (do_seal) {
netsec_do_seal(state, seq_num,
confounder,
data, length);
}
(*sig) = data_blob_talloc(mem_ctx, NULL, 32);
netsec_do_seq_num(state, checksum, checksum_length, seq_num);
memcpy(sig->data, netsec_sig, 8);
(*sig) = data_blob_talloc_zero(mem_ctx, used_sig_size);
memcpy(sig->data, header, 8);
memcpy(sig->data+8, seq_num, 8);
memcpy(sig->data+16, digest_final, 8);
memcpy(sig->data+24, confounder, 8);
memcpy(sig->data+16, checksum, checksum_length);
if (confounder) {
memcpy(sig->data+confounder_ofs, confounder, 8);
}
dump_data_pw("signature:", sig->data+ 0, 8);
dump_data_pw("seq_num :", sig->data+ 8, 8);
dump_data_pw("digest :", sig->data+16, 8);
dump_data_pw("confound :", sig->data+24, 8);
return NT_STATUS_OK;
}
/*
sign a packet
*/
NTSTATUS schannel_sign_packet(struct schannel_state *state,
TALLOC_CTX *mem_ctx,
const uint8_t *data, size_t length,
DATA_BLOB *sig)
{
uint8_t digest_final[16];
uint8_t seq_num[8];
static const uint8_t netsec_sig[8] = NETSEC_SIGN_SIGNATURE;
RSIVAL(seq_num, 0, state->seq_num);
SIVAL(seq_num, 4, state->initiator?0x80:0);
schannel_digest(state->creds->session_key,
netsec_sig, NULL,
data, length, digest_final);
netsec_deal_with_seq_num(state, digest_final, seq_num);
(*sig) = data_blob_talloc(mem_ctx, NULL, 32);
memcpy(sig->data, netsec_sig, 8);
memcpy(sig->data+8, seq_num, 8);
memcpy(sig->data+16, digest_final, 8);
memset(sig->data+24, 0, 8);
dump_data_pw("signature:", sig->data+ 0, 8);
dump_data_pw("seq_num :", sig->data+ 8, 8);
dump_data_pw("digest :", sig->data+16, 8);
dump_data_pw("confound :", sig->data+24, 8);
dump_data_pw("digest :", sig->data+16, checksum_length);
dump_data_pw("confound :", sig->data+confounder_ofs, 8);
return NT_STATUS_OK;
}

41
source3/rpc_client/cli_pipe.c
View File

@ -676,6 +676,7 @@ static NTSTATUS cli_pipe_verify_schannel(struct rpc_pipe_client *cli, RPC_HDR *p
uint32 save_offset = prs_offset(current_pdu);
struct schannel_state *schannel_auth =
cli->auth->a_u.schannel_auth;
uint8_t *data;
uint32 data_len;
DATA_BLOB blob;
NTSTATUS status;
@ -727,20 +728,24 @@ static NTSTATUS cli_pipe_verify_schannel(struct rpc_pipe_client *cli, RPC_HDR *p
dump_NL_AUTH_SIGNATURE(talloc_tos(), &blob);
}
data = (uint8_t *)prs_data_p(current_pdu)+RPC_HEADER_LEN+RPC_HDR_RESP_LEN;
switch (cli->auth->auth_level) {
case DCERPC_AUTH_LEVEL_PRIVACY:
status = schannel_unseal_packet(schannel_auth,
status = netsec_incoming_packet(schannel_auth,
talloc_tos(),
(uint8_t *)prs_data_p(current_pdu)+RPC_HEADER_LEN+RPC_HDR_RESP_LEN,
true,
data,
data_len,
&blob);
break;
case DCERPC_AUTH_LEVEL_INTEGRITY:
status = schannel_check_packet(schannel_auth,
talloc_tos(),
(uint8_t *)prs_data_p(current_pdu)+RPC_HEADER_LEN+RPC_HDR_RESP_LEN,
data_len,
&blob);
status = netsec_incoming_packet(schannel_auth,
talloc_tos(),
false,
data,
data_len,
&blob);
break;
default:
status = NT_STATUS_INTERNAL_ERROR;
@ -1948,18 +1953,20 @@ static NTSTATUS add_schannel_auth_footer(struct rpc_pipe_client *cli,
switch (cli->auth->auth_level) {
case DCERPC_AUTH_LEVEL_PRIVACY:
status = schannel_seal_packet(sas,
talloc_tos(),
(uint8_t *)data_p,
data_and_pad_len,
&blob);
status = netsec_outgoing_packet(sas,
talloc_tos(),
true,
(uint8_t *)data_p,
data_and_pad_len,
&blob);
break;
case DCERPC_AUTH_LEVEL_INTEGRITY:
status = schannel_sign_packet(sas,
talloc_tos(),
(uint8_t *)data_p,
data_and_pad_len,
&blob);
status = netsec_outgoing_packet(sas,
talloc_tos(),
false,
(uint8_t *)data_p,
data_and_pad_len,
&blob);
break;
default:
status = NT_STATUS_INTERNAL_ERROR;

44
source3/rpc_server/srv_pipe.c
View File

@ -411,6 +411,7 @@ static bool create_next_pdu_schannel(pipes_struct *p)
*/
RPC_HDR_AUTH auth_info;
DATA_BLOB blob;
uint8_t *data;
/* Check it's the type of reply we were expecting to decode */
@ -427,20 +428,24 @@ static bool create_next_pdu_schannel(pipes_struct *p)
return False;
}
data = (uint8_t *)prs_data_p(&p->out_data.frag) + data_pos;
switch (p->auth.auth_level) {
case DCERPC_AUTH_LEVEL_PRIVACY:
status = schannel_seal_packet(p->auth.a_u.schannel_auth,
talloc_tos(),
(uint8_t *)prs_data_p(&p->out_data.frag) + data_pos,
data_len + ss_padding_len,
&blob);
status = netsec_outgoing_packet(p->auth.a_u.schannel_auth,
talloc_tos(),
true,
data,
data_len + ss_padding_len,
&blob);
break;
case DCERPC_AUTH_LEVEL_INTEGRITY:
status = schannel_sign_packet(p->auth.a_u.schannel_auth,
talloc_tos(),
(uint8_t *)prs_data_p(&p->out_data.frag) + data_pos,
data_len + ss_padding_len,
&blob);
status = netsec_outgoing_packet(p->auth.a_u.schannel_auth,
talloc_tos(),
false,
data,
data_len + ss_padding_len,
&blob);
break;
default:
status = NT_STATUS_INTERNAL_ERROR;
@ -2162,6 +2167,7 @@ bool api_pipe_schannel_process(pipes_struct *p, prs_struct *rpc_in, uint32 *p_ss
RPC_HDR_AUTH auth_info;
DATA_BLOB blob;
NTSTATUS status;
uint8_t *data;
auth_len = p->hdr.auth_len;
@ -2215,20 +2221,24 @@ bool api_pipe_schannel_process(pipes_struct *p, prs_struct *rpc_in, uint32 *p_ss
dump_NL_AUTH_SIGNATURE(talloc_tos(), &blob);
}
data = (uint8_t *)prs_data_p(rpc_in)+RPC_HDR_REQ_LEN;
switch (auth_info.auth_level) {
case DCERPC_AUTH_LEVEL_PRIVACY:
status = schannel_unseal_packet(p->auth.a_u.schannel_auth,
status = netsec_incoming_packet(p->auth.a_u.schannel_auth,
talloc_tos(),
(uint8_t *)prs_data_p(rpc_in)+RPC_HDR_REQ_LEN,
true,
data,
data_len,
&blob);
break;
case DCERPC_AUTH_LEVEL_INTEGRITY:
status = schannel_check_packet(p->auth.a_u.schannel_auth,
talloc_tos(),
(uint8_t *)prs_data_p(rpc_in)+RPC_HDR_REQ_LEN,
data_len,
&blob);
status = netsec_incoming_packet(p->auth.a_u.schannel_auth,
talloc_tos(),
false,
data,
data_len,
&blob);
break;
default:
status = NT_STATUS_INTERNAL_ERROR;

95
source4/auth/gensec/schannel.c
View File

@ -282,48 +282,71 @@ static bool schannel_have_feature(struct gensec_security *gensec_security,
return false;
}
static NTSTATUS schannel_seal_packet_wrap(struct gensec_security *gensec_security,
TALLOC_CTX *mem_ctx,
uint8_t *data, size_t length,
const uint8_t *whole_pdu, size_t pdu_length,
DATA_BLOB *sig)
/*
unseal a packet
*/
static NTSTATUS schannel_unseal_packet(struct gensec_security *gensec_security,
TALLOC_CTX *mem_ctx,
uint8_t *data, size_t length,
const uint8_t *whole_pdu, size_t pdu_length,
const DATA_BLOB *sig)
{
struct schannel_state *state = talloc_get_type(gensec_security->private_data, struct schannel_state);
struct schannel_state *state =
talloc_get_type(gensec_security->private_data,
struct schannel_state);
return schannel_seal_packet(state, mem_ctx, data, length, sig);
return netsec_incoming_packet(state, mem_ctx, true,
data, length, sig);
}
static NTSTATUS schannel_sign_packet_wrap(struct gensec_security *gensec_security,
TALLOC_CTX *mem_ctx,
const uint8_t *data, size_t length,
const uint8_t *whole_pdu, size_t pdu_length,
DATA_BLOB *sig)
/*
check the signature on a packet
*/
static NTSTATUS schannel_check_packet(struct gensec_security *gensec_security,
TALLOC_CTX *mem_ctx,
const uint8_t *data, size_t length,
const uint8_t *whole_pdu, size_t pdu_length,
const DATA_BLOB *sig)
{
struct schannel_state *state = talloc_get_type(gensec_security->private_data, struct schannel_state);
struct schannel_state *state =
talloc_get_type(gensec_security->private_data,
struct schannel_state);
return schannel_sign_packet(state, mem_ctx, data, length, sig);
return netsec_incoming_packet(state, mem_ctx, false,
data, length, sig);
}
/*
seal a packet
*/
static NTSTATUS schannel_seal_packet(struct gensec_security *gensec_security,
TALLOC_CTX *mem_ctx,
uint8_t *data, size_t length,
const uint8_t *whole_pdu, size_t pdu_length,
DATA_BLOB *sig)
{
struct schannel_state *state =
talloc_get_type(gensec_security->private_data,
struct schannel_state);
return netsec_outgoing_packet(state, mem_ctx, true,
data, length, sig);
}
static NTSTATUS schannel_check_packet_wrap(struct gensec_security *gensec_security,
TALLOC_CTX *mem_ctx,
const uint8_t *data, size_t length,
const uint8_t *whole_pdu, size_t pdu_length,
const DATA_BLOB *sig)
/*
sign a packet
*/
static NTSTATUS schannel_sign_packet(struct gensec_security *gensec_security,
TALLOC_CTX *mem_ctx,
const uint8_t *data, size_t length,
const uint8_t *whole_pdu, size_t pdu_length,
DATA_BLOB *sig)
{
struct schannel_state *state = talloc_get_type(gensec_security->private_data, struct schannel_state);
struct schannel_state *state =
talloc_get_type(gensec_security->private_data,
struct schannel_state);
return schannel_check_packet(state, mem_ctx, data, length, sig);
}
static NTSTATUS schannel_unseal_packet_wrap(struct gensec_security *gensec_security,
TALLOC_CTX *mem_ctx,
uint8_t *data, size_t length,
const uint8_t *whole_pdu, size_t pdu_length,
const DATA_BLOB *sig)
{
struct schannel_state *state = talloc_get_type(gensec_security->private_data, struct schannel_state);
return schannel_unseal_packet(state, mem_ctx, data, length, sig);
return netsec_outgoing_packet(state, mem_ctx, false,
data, length, sig);
}
static const struct gensec_security_ops gensec_schannel_security_ops = {
@ -332,10 +355,10 @@ static const struct gensec_security_ops gensec_schannel_security_ops = {
.client_start = schannel_client_start,
.server_start = schannel_server_start,
.update = schannel_update,
.seal_packet = schannel_seal_packet_wrap,
.sign_packet = schannel_sign_packet_wrap,
.check_packet = schannel_check_packet_wrap,
.unseal_packet = schannel_unseal_packet_wrap,
.seal_packet = schannel_seal_packet,
.sign_packet = schannel_sign_packet,
.check_packet = schannel_check_packet,
.unseal_packet = schannel_unseal_packet,
.session_key = schannel_session_key,
.session_info = schannel_session_info,
.sig_size = schannel_sig_size,