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kex.c
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/* Copyright (C) Sara Golemon <[email protected]>
* Copyright (C) Daniel Stenberg <[email protected]>
* All rights reserved.
*
* Redistribution and use in source and binary forms,
* with or without modification, are permitted provided
* that the following conditions are met:
*
* Redistributions of source code must retain the above
* copyright notice, this list of conditions and the
* following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* Neither the name of the copyright holder nor the names
* of any other contributors may be used to endorse or
* promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "libssh2_priv.h"
#include "transport.h"
#include "comp.h"
#include "mac.h"
#include <assert.h>
/* define SHA1_DIGEST_LENGTH for the macro below */
#ifndef SHA1_DIGEST_LENGTH
#define SHA1_DIGEST_LENGTH SHA_DIGEST_LENGTH
#endif
/* TODO: Switch this to an inline and handle alloc() failures */
/* Helper macro called from
kex_method_diffie_hellman_group1_sha1_key_exchange */
#if LIBSSH2_ECDSA
#define LIBSSH2_KEX_METHOD_EC_SHA_VALUE_HASH(value, reqlen, version) \
do { \
if(type == LIBSSH2_EC_CURVE_NISTP256) { \
LIBSSH2_KEX_METHOD_SHA_VALUE_HASH(256, value, reqlen, version); \
} \
else if(type == LIBSSH2_EC_CURVE_NISTP384) { \
LIBSSH2_KEX_METHOD_SHA_VALUE_HASH(384, value, reqlen, version); \
} \
else if(type == LIBSSH2_EC_CURVE_NISTP521) { \
LIBSSH2_KEX_METHOD_SHA_VALUE_HASH(512, value, reqlen, version); \
} \
} while(0)
#endif
#define LIBSSH2_KEX_METHOD_SHA_VALUE_HASH(digest_type, value, \
reqlen, version) \
do { \
libssh2_sha##digest_type##_ctx hash; \
size_t len = 0; \
if(!(value)) { \
value = LIBSSH2_ALLOC(session, \
reqlen + SHA##digest_type##_DIGEST_LENGTH); \
} \
if(value) \
while(len < (size_t)reqlen) { \
if(!libssh2_sha##digest_type##_init(&hash) || \
!libssh2_sha##digest_type##_update(hash, \
exchange_state->k_value, \
exchange_state->k_value_len) || \
!libssh2_sha##digest_type##_update(hash, \
exchange_state->h_sig_comp, \
SHA##digest_type##_DIGEST_LENGTH)) { \
LIBSSH2_FREE(session, value); \
value = NULL; \
break; \
} \
if(len > 0) { \
if(!libssh2_sha##digest_type##_update(hash, value, len)) { \
LIBSSH2_FREE(session, value); \
value = NULL; \
break; \
} \
} \
else { \
if(!libssh2_sha##digest_type##_update(hash, \
(version), 1) || \
!libssh2_sha##digest_type##_update(hash, \
session->session_id, \
session->session_id_len)) { \
LIBSSH2_FREE(session, value); \
value = NULL; \
break; \
} \
} \
if(!libssh2_sha##digest_type##_final(hash, (value) + len)) { \
LIBSSH2_FREE(session, value); \
value = NULL; \
break; \
} \
len += SHA##digest_type##_DIGEST_LENGTH; \
} \
} while(0)
/*!
* @note The following are wrapper functions used by diffie_hellman_sha_algo().
* TODO: Switch backend SHA macros to functions to allow function pointers
* @discussion Ideally these would be function pointers but the backend macros
* don't allow it so we have to wrap them up in helper functions
*/
static int _libssh2_sha_algo_ctx_init(int sha_algo, void *ctx)
{
if(sha_algo == 512) {
return libssh2_sha512_init((libssh2_sha512_ctx*)ctx);
}
else if(sha_algo == 384) {
return libssh2_sha384_init((libssh2_sha384_ctx*)ctx);
}
else if(sha_algo == 256) {
return libssh2_sha256_init((libssh2_sha256_ctx*)ctx);
}
else if(sha_algo == 1) {
return libssh2_sha1_init((libssh2_sha1_ctx*)ctx);
}
else {
#ifdef LIBSSH2DEBUG
assert(0);
#endif
}
return 0;
}
static int _libssh2_sha_algo_ctx_update(int sha_algo, void *ctx,
const void *data, size_t len)
{
if(sha_algo == 512) {
libssh2_sha512_ctx *_ctx = (libssh2_sha512_ctx*)ctx;
return libssh2_sha512_update(*_ctx, data, len);
}
else if(sha_algo == 384) {
libssh2_sha384_ctx *_ctx = (libssh2_sha384_ctx*)ctx;
return libssh2_sha384_update(*_ctx, data, len);
}
else if(sha_algo == 256) {
libssh2_sha256_ctx *_ctx = (libssh2_sha256_ctx*)ctx;
return libssh2_sha256_update(*_ctx, data, len);
}
else if(sha_algo == 1) {
libssh2_sha1_ctx *_ctx = (libssh2_sha1_ctx*)ctx;
return libssh2_sha1_update(*_ctx, data, len);
}
else {
#ifdef LIBSSH2DEBUG
assert(0);
#endif
}
return 0;
}
static int _libssh2_sha_algo_ctx_final(int sha_algo, void *ctx,
void *hash)
{
if(sha_algo == 512) {
libssh2_sha512_ctx *_ctx = (libssh2_sha512_ctx*)ctx;
return libssh2_sha512_final(*_ctx, hash);
}
else if(sha_algo == 384) {
libssh2_sha384_ctx *_ctx = (libssh2_sha384_ctx*)ctx;
return libssh2_sha384_final(*_ctx, hash);
}
else if(sha_algo == 256) {
libssh2_sha256_ctx *_ctx = (libssh2_sha256_ctx*)ctx;
return libssh2_sha256_final(*_ctx, hash);
}
else if(sha_algo == 1) {
libssh2_sha1_ctx *_ctx = (libssh2_sha1_ctx*)ctx;
return libssh2_sha1_final(*_ctx, hash);
}
else {
#ifdef LIBSSH2DEBUG
assert(0);
#endif
}
return 0;
}
static void _libssh2_sha_algo_value_hash(int sha_algo,
LIBSSH2_SESSION *session,
kmdhgGPshakex_state_t *exchange_state,
unsigned char **data, size_t data_len,
const unsigned char *version)
{
if(sha_algo == 512) {
LIBSSH2_KEX_METHOD_SHA_VALUE_HASH(512, *data, data_len, version);
}
else if(sha_algo == 384) {
LIBSSH2_KEX_METHOD_SHA_VALUE_HASH(384, *data, data_len, version);
}
else if(sha_algo == 256) {
LIBSSH2_KEX_METHOD_SHA_VALUE_HASH(256, *data, data_len, version);
}
else if(sha_algo == 1) {
LIBSSH2_KEX_METHOD_SHA_VALUE_HASH(1, *data, data_len, version);
}
else {
#ifdef LIBSSH2DEBUG
assert(0);
#endif
}
}
static void
diffie_hellman_state_cleanup(LIBSSH2_SESSION * session,
kmdhgGPshakex_state_t *exchange_state)
{
libssh2_dh_dtor(&exchange_state->x);
_libssh2_bn_free(exchange_state->e);
exchange_state->e = NULL;
_libssh2_bn_free(exchange_state->f);
exchange_state->f = NULL;
_libssh2_bn_free(exchange_state->k);
exchange_state->k = NULL;
_libssh2_bn_ctx_free(exchange_state->ctx);
exchange_state->ctx = NULL;
if(exchange_state->e_packet) {
LIBSSH2_FREE(session, exchange_state->e_packet);
exchange_state->e_packet = NULL;
}
if(exchange_state->s_packet) {
LIBSSH2_FREE(session, exchange_state->s_packet);
exchange_state->s_packet = NULL;
}
if(exchange_state->k_value) {
LIBSSH2_FREE(session, exchange_state->k_value);
exchange_state->k_value = NULL;
}
exchange_state->state = libssh2_NB_state_idle;
}
static void
kex_diffie_hellman_cleanup(LIBSSH2_SESSION * session,
key_exchange_state_low_t * key_state) {
if(key_state->state != libssh2_NB_state_idle) {
_libssh2_bn_free(key_state->p);
key_state->p = NULL;
_libssh2_bn_free(key_state->g);
key_state->g = NULL;
if(key_state->data) {
LIBSSH2_FREE(session, key_state->data);
key_state->data = NULL;
}
key_state->state = libssh2_NB_state_idle;
}
if(key_state->exchange_state.state != libssh2_NB_state_idle) {
diffie_hellman_state_cleanup(session, &key_state->exchange_state);
}
}
/*!
* @function diffie_hellman_sha_algo
* @abstract Diffie Hellman Key Exchange, Group Agnostic,
* SHA Algorithm Agnostic
* @result 0 on success, error code on failure
*/
static int diffie_hellman_sha_algo(LIBSSH2_SESSION *session,
_libssh2_bn *g,
_libssh2_bn *p,
int group_order,
int sha_algo_value,
void *exchange_hash_ctx,
unsigned char packet_type_init,
unsigned char packet_type_reply,
unsigned char *midhash,
size_t midhash_len,
kmdhgGPshakex_state_t *exchange_state)
{
int ret = 0;
int rc;
int digest_len = 0;
if(sha_algo_value == 512)
digest_len = SHA512_DIGEST_LENGTH;
else if(sha_algo_value == 384)
digest_len = SHA384_DIGEST_LENGTH;
else if(sha_algo_value == 256)
digest_len = SHA256_DIGEST_LENGTH;
else if(sha_algo_value == 1)
digest_len = SHA1_DIGEST_LENGTH;
else {
ret = _libssh2_error(session, LIBSSH2_ERROR_PROTO,
"sha algo value is unimplemented");
goto clean_exit;
}
if(exchange_state->state == libssh2_NB_state_idle) {
/* Setup initial values */
exchange_state->e_packet = NULL;
exchange_state->s_packet = NULL;
exchange_state->k_value = NULL;
exchange_state->ctx = _libssh2_bn_ctx_new();
libssh2_dh_init(&exchange_state->x);
exchange_state->e = _libssh2_bn_init(); /* g^x mod p */
exchange_state->f = _libssh2_bn_init_from_bin(); /* g^(Random from
server) mod p */
exchange_state->k = _libssh2_bn_init(); /* The shared secret: f^x mod
p */
/* Zero the whole thing out */
memset(&exchange_state->req_state, 0, sizeof(packet_require_state_t));
/* Generate x and e */
if(_libssh2_bn_bits(p) > LIBSSH2_DH_MAX_MODULUS_BITS) {
ret = _libssh2_error(session, LIBSSH2_ERROR_INVAL,
"dh modulus value is too large");
goto clean_exit;
}
rc = libssh2_dh_key_pair(&exchange_state->x, exchange_state->e, g, p,
group_order, exchange_state->ctx);
if(rc) {
ret = _libssh2_error(session, LIBSSH2_ERROR_KEX_FAILURE,
"dh key pair generation failed");
goto clean_exit;
}
/* Send KEX init */
/* packet_type(1) + String Length(4) + leading 0(1) */
exchange_state->e_packet_len =
_libssh2_bn_bytes(exchange_state->e) + 6;
if(_libssh2_bn_bits(exchange_state->e) % 8) {
/* Leading 00 not needed */
exchange_state->e_packet_len--;
}
exchange_state->e_packet =
LIBSSH2_ALLOC(session, exchange_state->e_packet_len);
if(!exchange_state->e_packet) {
ret = _libssh2_error(session, LIBSSH2_ERROR_ALLOC,
"Out of memory error");
goto clean_exit;
}
exchange_state->e_packet[0] = packet_type_init;
_libssh2_htonu32(exchange_state->e_packet + 1,
(uint32_t)(exchange_state->e_packet_len - 5));
if(_libssh2_bn_bits(exchange_state->e) % 8) {
if(_libssh2_bn_to_bin(exchange_state->e,
exchange_state->e_packet + 5)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_OUT_OF_BOUNDARY,
"Can't write exchange_state->e");
goto clean_exit;
}
}
else {
exchange_state->e_packet[5] = 0;
if(_libssh2_bn_to_bin(exchange_state->e,
exchange_state->e_packet + 6)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_OUT_OF_BOUNDARY,
"Can't write exchange_state->e");
goto clean_exit;
}
}
_libssh2_debug((session, LIBSSH2_TRACE_KEX, "Sending KEX packet %u",
(unsigned int) packet_type_init));
exchange_state->state = libssh2_NB_state_created;
}
if(exchange_state->state == libssh2_NB_state_created) {
rc = _libssh2_transport_send(session, exchange_state->e_packet,
exchange_state->e_packet_len,
NULL, 0);
if(rc == LIBSSH2_ERROR_EAGAIN) {
return rc;
}
else if(rc) {
ret = _libssh2_error(session, rc,
"Unable to send KEX init message");
goto clean_exit;
}
exchange_state->state = libssh2_NB_state_sent;
}
if(exchange_state->state == libssh2_NB_state_sent) {
if(session->burn_optimistic_kexinit) {
/* The first KEX packet to come along will be the guess initially
* sent by the server. That guess turned out to be wrong so we
* need to silently ignore it */
int burn_type;
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Waiting for badly guessed KEX packet "
"(to be ignored)"));
burn_type =
_libssh2_packet_burn(session, &exchange_state->burn_state);
if(burn_type == LIBSSH2_ERROR_EAGAIN) {
return burn_type;
}
else if(burn_type <= 0) {
/* Failed to receive a packet */
ret = burn_type;
goto clean_exit;
}
session->burn_optimistic_kexinit = 0;
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Burnt packet of type: %02x",
(unsigned int) burn_type));
}
exchange_state->state = libssh2_NB_state_sent1;
}
if(exchange_state->state == libssh2_NB_state_sent1) {
/* Wait for KEX reply */
struct string_buf buf;
size_t host_key_len;
int err;
int hok;
rc = _libssh2_packet_require(session, packet_type_reply,
&exchange_state->s_packet,
&exchange_state->s_packet_len, 0, NULL,
0, &exchange_state->req_state);
if(rc == LIBSSH2_ERROR_EAGAIN) {
return rc;
}
if(rc) {
ret = _libssh2_error(session, LIBSSH2_ERROR_TIMEOUT,
"Timed out waiting for KEX reply");
goto clean_exit;
}
/* Parse KEXDH_REPLY */
if(exchange_state->s_packet_len < 5) {
ret = _libssh2_error(session, LIBSSH2_ERROR_PROTO,
"Unexpected packet length DH-SHA");
goto clean_exit;
}
buf.data = exchange_state->s_packet;
buf.len = exchange_state->s_packet_len;
buf.dataptr = buf.data;
buf.dataptr++; /* advance past type */
if(session->server_hostkey) {
LIBSSH2_FREE(session, session->server_hostkey);
session->server_hostkey = NULL;
session->server_hostkey_len = 0;
}
if(_libssh2_copy_string(session, &buf, &(session->server_hostkey),
&host_key_len)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_ALLOC,
"Could not copy host key");
goto clean_exit;
}
session->server_hostkey_len = (uint32_t)host_key_len;
#if LIBSSH2_MD5
{
libssh2_md5_ctx fingerprint_ctx;
if(libssh2_md5_init(&fingerprint_ctx) &&
libssh2_md5_update(fingerprint_ctx, session->server_hostkey,
session->server_hostkey_len) &&
libssh2_md5_final(fingerprint_ctx,
session->server_hostkey_md5)) {
session->server_hostkey_md5_valid = TRUE;
}
else {
session->server_hostkey_md5_valid = FALSE;
}
}
#ifdef LIBSSH2DEBUG
{
char fingerprint[50], *fprint = fingerprint;
int i;
for(i = 0; i < 16; i++, fprint += 3) {
snprintf(fprint, 4, "%02x:", session->server_hostkey_md5[i]);
}
*(--fprint) = '\0';
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Server's MD5 Fingerprint: %s", fingerprint));
}
#endif /* LIBSSH2DEBUG */
#endif /* ! LIBSSH2_MD5 */
{
libssh2_sha1_ctx fingerprint_ctx;
if(libssh2_sha1_init(&fingerprint_ctx) &&
libssh2_sha1_update(fingerprint_ctx, session->server_hostkey,
session->server_hostkey_len) &&
libssh2_sha1_final(fingerprint_ctx,
session->server_hostkey_sha1)) {
session->server_hostkey_sha1_valid = TRUE;
}
else {
session->server_hostkey_sha1_valid = FALSE;
}
}
#ifdef LIBSSH2DEBUG
{
char fingerprint[64], *fprint = fingerprint;
int i;
for(i = 0; i < 20; i++, fprint += 3) {
snprintf(fprint, 4, "%02x:", session->server_hostkey_sha1[i]);
}
*(--fprint) = '\0';
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Server's SHA1 Fingerprint: %s", fingerprint));
}
#endif /* LIBSSH2DEBUG */
{
libssh2_sha256_ctx fingerprint_ctx;
if(libssh2_sha256_init(&fingerprint_ctx) &&
libssh2_sha256_update(fingerprint_ctx, session->server_hostkey,
session->server_hostkey_len) &&
libssh2_sha256_final(fingerprint_ctx,
session->server_hostkey_sha256)) {
session->server_hostkey_sha256_valid = TRUE;
}
else {
session->server_hostkey_sha256_valid = FALSE;
}
}
#ifdef LIBSSH2DEBUG
{
char *base64Fingerprint = NULL;
_libssh2_base64_encode(session,
(const char *)
session->server_hostkey_sha256,
SHA256_DIGEST_LENGTH, &base64Fingerprint);
if(base64Fingerprint) {
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Server's SHA256 Fingerprint: %s",
base64Fingerprint));
LIBSSH2_FREE(session, base64Fingerprint);
}
}
#endif /* LIBSSH2DEBUG */
if(!session->hostkey) {
ret = _libssh2_error(session, LIBSSH2_ERROR_PROTO,
"hostkey is NULL");
goto clean_exit;
}
if(session->hostkey->init(session, session->server_hostkey,
session->server_hostkey_len,
&session->server_hostkey_abstract)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_HOSTKEY_INIT,
"Unable to initialize hostkey importer "
"DH-SHA");
goto clean_exit;
}
if(_libssh2_get_string(&buf, &(exchange_state->f_value),
&(exchange_state->f_value_len))) {
ret = _libssh2_error(session, LIBSSH2_ERROR_HOSTKEY_INIT,
"Unable to get DH-SHA f value");
goto clean_exit;
}
if(_libssh2_bn_from_bin(exchange_state->f,
exchange_state->f_value_len,
exchange_state->f_value)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_HOSTKEY_INIT,
"Invalid DH-SHA f value");
goto clean_exit;
}
if(_libssh2_get_string(&buf, &(exchange_state->h_sig),
&(exchange_state->h_sig_len))) {
ret = _libssh2_error(session, LIBSSH2_ERROR_HOSTKEY_INIT,
"Unable to get DH-SHA h sig");
goto clean_exit;
}
/* Compute the shared secret */
libssh2_dh_secret(&exchange_state->x, exchange_state->k,
exchange_state->f, p, exchange_state->ctx);
exchange_state->k_value_len = _libssh2_bn_bytes(exchange_state->k) + 5;
if(_libssh2_bn_bits(exchange_state->k) % 8) {
/* don't need leading 00 */
exchange_state->k_value_len--;
}
exchange_state->k_value =
LIBSSH2_ALLOC(session, exchange_state->k_value_len);
if(!exchange_state->k_value) {
ret = _libssh2_error(session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate buffer for DH-SHA K");
goto clean_exit;
}
_libssh2_htonu32(exchange_state->k_value,
(uint32_t)(exchange_state->k_value_len - 4));
if(_libssh2_bn_bits(exchange_state->k) % 8) {
if(_libssh2_bn_to_bin(exchange_state->k,
exchange_state->k_value + 4)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_OUT_OF_BOUNDARY,
"Can't write exchange_state->k");
goto clean_exit;
}
}
else {
exchange_state->k_value[4] = 0;
if(_libssh2_bn_to_bin(exchange_state->k,
exchange_state->k_value + 5)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_OUT_OF_BOUNDARY,
"Can't write exchange_state->k");
goto clean_exit;
}
}
exchange_state->exchange_hash = (void *)&exchange_hash_ctx;
if(!_libssh2_sha_algo_ctx_init(sha_algo_value, exchange_hash_ctx)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_HASH_INIT,
"Unable to initialize hash context");
goto clean_exit;
}
hok = 1;
if(session->local.banner) {
_libssh2_htonu32(exchange_state->h_sig_comp,
(uint32_t)(strlen((char *) session->local.banner) - 2));
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value,
exchange_hash_ctx,
exchange_state->h_sig_comp, 4);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value,
exchange_hash_ctx,
session->local.banner,
strlen((char *) session->local.banner) - 2);
}
else {
_libssh2_htonu32(exchange_state->h_sig_comp,
sizeof(LIBSSH2_SSH_DEFAULT_BANNER) - 1);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value,
exchange_hash_ctx,
exchange_state->h_sig_comp, 4);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value,
exchange_hash_ctx,
(const void *)LIBSSH2_SSH_DEFAULT_BANNER,
sizeof(LIBSSH2_SSH_DEFAULT_BANNER) - 1);
}
_libssh2_htonu32(exchange_state->h_sig_comp,
(uint32_t)strlen((char *) session->remote.banner));
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
exchange_state->h_sig_comp, 4);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
session->remote.banner,
strlen((char *)session->remote.banner));
_libssh2_htonu32(exchange_state->h_sig_comp,
(uint32_t)session->local.kexinit_len);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
exchange_state->h_sig_comp, 4);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
session->local.kexinit,
session->local.kexinit_len);
_libssh2_htonu32(exchange_state->h_sig_comp,
(uint32_t)session->remote.kexinit_len);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
exchange_state->h_sig_comp, 4);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
session->remote.kexinit,
session->remote.kexinit_len);
_libssh2_htonu32(exchange_state->h_sig_comp,
session->server_hostkey_len);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
exchange_state->h_sig_comp, 4);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
session->server_hostkey,
session->server_hostkey_len);
if(packet_type_init == SSH_MSG_KEX_DH_GEX_INIT) {
/* diffie-hellman-group-exchange hashes additional fields */
_libssh2_htonu32(exchange_state->h_sig_comp,
LIBSSH2_DH_GEX_MINGROUP);
_libssh2_htonu32(exchange_state->h_sig_comp + 4,
LIBSSH2_DH_GEX_OPTGROUP);
_libssh2_htonu32(exchange_state->h_sig_comp + 8,
LIBSSH2_DH_GEX_MAXGROUP);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value,
exchange_hash_ctx,
exchange_state->h_sig_comp,
12);
}
if(midhash) {
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value,
exchange_hash_ctx,
midhash, midhash_len);
}
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
exchange_state->e_packet + 1,
exchange_state->e_packet_len - 1);
_libssh2_htonu32(exchange_state->h_sig_comp,
(uint32_t)exchange_state->f_value_len);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
exchange_state->h_sig_comp, 4);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
exchange_state->f_value,
exchange_state->f_value_len);
hok &= _libssh2_sha_algo_ctx_update(sha_algo_value, exchange_hash_ctx,
exchange_state->k_value,
exchange_state->k_value_len);
if(!hok ||
!_libssh2_sha_algo_ctx_final(sha_algo_value, exchange_hash_ctx,
exchange_state->h_sig_comp)) {
ret = _libssh2_error(session, LIBSSH2_ERROR_HASH_CALC,
"kex: failed to calculate hash");
goto clean_exit;
}
err = session->hostkey->sig_verify(session,
exchange_state->h_sig,
exchange_state->h_sig_len,
exchange_state->h_sig_comp,
digest_len,
&session->server_hostkey_abstract);
if(err) {
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Failed hostkey sig_verify(): %s: %d",
session->hostkey->name, err));
ret = _libssh2_error(session, LIBSSH2_ERROR_HOSTKEY_SIGN,
"Unable to verify hostkey signature "
"DH-SHA");
goto clean_exit;
}
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Sending NEWKEYS message"));
exchange_state->c = SSH_MSG_NEWKEYS;
exchange_state->state = libssh2_NB_state_sent2;
}
if(exchange_state->state == libssh2_NB_state_sent2) {
rc = _libssh2_transport_send(session, &exchange_state->c, 1, NULL, 0);
if(rc == LIBSSH2_ERROR_EAGAIN) {
return rc;
}
else if(rc) {
ret = _libssh2_error(session, rc,
"Unable to send NEWKEYS message DH-SHA");
goto clean_exit;
}
exchange_state->state = libssh2_NB_state_sent3;
}
if(exchange_state->state == libssh2_NB_state_sent3) {
rc = _libssh2_packet_require(session, SSH_MSG_NEWKEYS,
&exchange_state->tmp,
&exchange_state->tmp_len, 0, NULL, 0,
&exchange_state->req_state);
if(rc == LIBSSH2_ERROR_EAGAIN) {
return rc;
}
else if(rc) {
ret = _libssh2_error(session, rc,
"Timed out waiting for NEWKEYS DH-SHA");
goto clean_exit;
}
/* The first key exchange has been performed,
switch to active crypt/comp/mac mode */
session->state |= LIBSSH2_STATE_NEWKEYS;
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Received NEWKEYS message DH-SHA"));
/* This will actually end up being just packet_type(1)
for this packet type anyway */
LIBSSH2_FREE(session, exchange_state->tmp);
if(!session->session_id) {
session->session_id = LIBSSH2_ALLOC(session, digest_len);
if(!session->session_id) {
ret = _libssh2_error(session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate buffer for "
"SHA digest");
goto clean_exit;
}
memcpy(session->session_id, exchange_state->h_sig_comp,
digest_len);
session->session_id_len = digest_len;
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"session_id calculated"));
}
/* Cleanup any existing cipher */
if(session->local.crypt->dtor) {
session->local.crypt->dtor(session,
&session->local.crypt_abstract);
}
/* Calculate IV/Secret/Key for each direction */
if(session->local.crypt->init) {
unsigned char *iv = NULL, *secret = NULL;
int free_iv = 0, free_secret = 0;
_libssh2_sha_algo_value_hash(sha_algo_value, session,
exchange_state, &iv,
session->local.crypt->iv_len,
(const unsigned char *)"A");
if(!iv) {
ret = -1;
goto clean_exit;
}
_libssh2_sha_algo_value_hash(sha_algo_value, session,
exchange_state, &secret,
session->local.crypt->secret_len,
(const unsigned char *)"C");
if(!secret) {
LIBSSH2_FREE(session, iv);
ret = LIBSSH2_ERROR_KEX_FAILURE;
goto clean_exit;
}
if(session->local.crypt->
init(session, session->local.crypt, iv, &free_iv, secret,
&free_secret, 1, &session->local.crypt_abstract)) {
LIBSSH2_FREE(session, iv);
LIBSSH2_FREE(session, secret);
ret = LIBSSH2_ERROR_KEX_FAILURE;
goto clean_exit;
}
if(free_iv) {
_libssh2_explicit_zero(iv, session->local.crypt->iv_len);
LIBSSH2_FREE(session, iv);
}
if(free_secret) {
_libssh2_explicit_zero(secret,
session->local.crypt->secret_len);
LIBSSH2_FREE(session, secret);
}
}
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Client to Server IV and Key calculated"));
if(session->remote.crypt->dtor) {
/* Cleanup any existing cipher */
session->remote.crypt->dtor(session,
&session->remote.crypt_abstract);
}
if(session->remote.crypt->init) {
unsigned char *iv = NULL, *secret = NULL;
int free_iv = 0, free_secret = 0;
_libssh2_sha_algo_value_hash(sha_algo_value, session,
exchange_state, &iv,
session->remote.crypt->iv_len,
(const unsigned char *)"B");
if(!iv) {
ret = LIBSSH2_ERROR_KEX_FAILURE;
goto clean_exit;
}
_libssh2_sha_algo_value_hash(sha_algo_value, session,
exchange_state, &secret,
session->remote.crypt->secret_len,
(const unsigned char *)"D");
if(!secret) {
LIBSSH2_FREE(session, iv);
ret = LIBSSH2_ERROR_KEX_FAILURE;
goto clean_exit;
}
if(session->remote.crypt->
init(session, session->remote.crypt, iv, &free_iv, secret,
&free_secret, 0, &session->remote.crypt_abstract)) {
LIBSSH2_FREE(session, iv);
LIBSSH2_FREE(session, secret);
ret = LIBSSH2_ERROR_KEX_FAILURE;
goto clean_exit;
}
if(free_iv) {
_libssh2_explicit_zero(iv, session->remote.crypt->iv_len);
LIBSSH2_FREE(session, iv);
}
if(free_secret) {
_libssh2_explicit_zero(secret,
session->remote.crypt->secret_len);
LIBSSH2_FREE(session, secret);
}
}
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Server to Client IV and Key calculated"));
if(session->local.mac->dtor) {
session->local.mac->dtor(session, &session->local.mac_abstract);
}
if(session->local.mac->init) {
unsigned char *key = NULL;
int free_key = 0;
_libssh2_sha_algo_value_hash(sha_algo_value, session,
exchange_state, &key,
session->local.mac->key_len,
(const unsigned char *)"E");
if(!key) {
ret = LIBSSH2_ERROR_KEX_FAILURE;
goto clean_exit;
}
session->local.mac->init(session, key, &free_key,
&session->local.mac_abstract);
if(free_key) {
_libssh2_explicit_zero(key, session->local.mac->key_len);
LIBSSH2_FREE(session, key);
}
}
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Client to Server HMAC Key calculated"));
if(session->remote.mac->dtor) {
session->remote.mac->dtor(session, &session->remote.mac_abstract);
}
if(session->remote.mac->init) {
unsigned char *key = NULL;
int free_key = 0;
_libssh2_sha_algo_value_hash(sha_algo_value, session,
exchange_state, &key,
session->remote.mac->key_len,
(const unsigned char *)"F");
if(!key) {
ret = LIBSSH2_ERROR_KEX_FAILURE;
goto clean_exit;
}
session->remote.mac->init(session, key, &free_key,
&session->remote.mac_abstract);
if(free_key) {
_libssh2_explicit_zero(key, session->remote.mac->key_len);
LIBSSH2_FREE(session, key);
}
}
_libssh2_debug((session, LIBSSH2_TRACE_KEX,
"Server to Client HMAC Key calculated"));
/* Initialize compression for each direction */
/* Cleanup any existing compression */
if(session->local.comp && session->local.comp->dtor) {
session->local.comp->dtor(session, 1,
&session->local.comp_abstract);
}
if(session->local.comp && session->local.comp->init) {
if(session->local.comp->init(session, 1,
&session->local.comp_abstract)) {
ret = LIBSSH2_ERROR_KEX_FAILURE;
goto clean_exit;
}
}
_libssh2_debug((session, LIBSSH2_TRACE_KEX,