static int dh_handshake_server(ssh_session session) {
ssh_key privkey;
ssh_string sig_blob;
ssh_string f;
ssh_string pubkey_blob = NULL;
int rc;
if (ssh_dh_generate_y(session) < 0) {
ssh_set_error(session, SSH_FATAL, "Could not create y number");
return -1;
}
if (ssh_dh_generate_f(session) < 0) {
ssh_set_error(session, SSH_FATAL, "Could not create f number");
return -1;
}
f = ssh_dh_get_f(session);
if (f == NULL) {
ssh_set_error(session, SSH_FATAL, "Could not get the f number");
return -1;
}
if (ssh_get_key_params(session,&privkey) != SSH_OK){
ssh_string_free(f);
return -1;
}
if (ssh_dh_build_k(session) < 0) {
ssh_set_error(session, SSH_FATAL, "Could not import the public key");
ssh_string_free(f);
return -1;
}
if (ssh_make_sessionid(session) != SSH_OK) {
ssh_set_error(session, SSH_FATAL, "Could not create a session id");
ssh_string_free(f);
return -1;
}
sig_blob = ssh_srv_pki_do_sign_sessionid(session, privkey);
if (sig_blob == NULL) {
ssh_set_error(session, SSH_FATAL, "Could not sign the session id");
ssh_string_free(f);
return -1;
}
rc = ssh_dh_get_next_server_publickey_blob(session, &pubkey_blob);
if (rc != SSH_OK) {
ssh_set_error_oom(session);
ssh_string_free(f);
ssh_string_free(sig_blob);
return -1;
}
rc = ssh_buffer_pack(session->out_buffer,
"bSSS",
SSH2_MSG_KEXDH_REPLY,
pubkey_blob,
f,
sig_blob);
ssh_string_free(f);
ssh_string_free(sig_blob);
ssh_string_free(pubkey_blob);
if(rc != SSH_OK){
ssh_set_error_oom(session);
ssh_buffer_reinit(session->out_buffer);
return -1;
}
if (ssh_packet_send(session) == SSH_ERROR) {
return -1;
}
if (ssh_buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS) < 0) {
ssh_buffer_reinit(session->out_buffer);
return -1;
}
if (ssh_packet_send(session) == SSH_ERROR) {
return -1;
}
SSH_LOG(SSH_LOG_PACKET, "SSH_MSG_NEWKEYS sent");
session->dh_handshake_state=DH_STATE_NEWKEYS_SENT;
return 0;
}
int ssh_make_sessionid(ssh_session session)
{
ssh_string num = NULL;
ssh_buffer server_hash = NULL;
ssh_buffer client_hash = NULL;
ssh_buffer buf = NULL;
ssh_string server_pubkey_blob = NULL;
const_bignum client_pubkey, server_pubkey;
#ifdef WITH_GEX
const_bignum modulus, generator;
#endif
int rc = SSH_ERROR;
buf = ssh_buffer_new();
if (buf == NULL) {
return rc;
}
rc = ssh_buffer_pack(buf,
"ss",
session->clientbanner,
session->serverbanner);
if (rc == SSH_ERROR) {
goto error;
}
if (session->client) {
server_hash = session->in_hashbuf;
client_hash = session->out_hashbuf;
} else {
server_hash = session->out_hashbuf;
client_hash = session->in_hashbuf;
}
/*
* Handle the two final fields for the KEXINIT message (RFC 4253 7.1):
*
* boolean first_kex_packet_follows
* uint32 0 (reserved for future extension)
*/
rc = ssh_buffer_add_u8(server_hash, 0);
if (rc < 0) {
goto error;
}
rc = ssh_buffer_add_u32(server_hash, 0);
if (rc < 0) {
goto error;
}
/* These fields are handled for the server case in ssh_packet_kexinit. */
if (session->client) {
rc = ssh_buffer_add_u8(client_hash, 0);
if (rc < 0) {
goto error;
}
rc = ssh_buffer_add_u32(client_hash, 0);
if (rc < 0) {
goto error;
}
}
rc = ssh_dh_get_next_server_publickey_blob(session, &server_pubkey_blob);
if (rc != SSH_OK) {
goto error;
}
rc = ssh_buffer_pack(buf,
"dPdPS",
ssh_buffer_get_len(client_hash),
ssh_buffer_get_len(client_hash),
ssh_buffer_get(client_hash),
ssh_buffer_get_len(server_hash),
ssh_buffer_get_len(server_hash),
ssh_buffer_get(server_hash),
server_pubkey_blob);
ssh_string_free(server_pubkey_blob);
if(rc != SSH_OK){
goto error;
}
switch(session->next_crypto->kex_type) {
case SSH_KEX_DH_GROUP1_SHA1:
case SSH_KEX_DH_GROUP14_SHA1:
case SSH_KEX_DH_GROUP16_SHA512:
case SSH_KEX_DH_GROUP18_SHA512:
rc = ssh_dh_keypair_get_keys(session->next_crypto->dh_ctx,
DH_CLIENT_KEYPAIR, NULL, &client_pubkey);
if (rc != SSH_OK) {
goto error;
}
rc = ssh_dh_keypair_get_keys(session->next_crypto->dh_ctx,
DH_SERVER_KEYPAIR, NULL, &server_pubkey);
if (rc != SSH_OK) {
goto error;
}
rc = ssh_buffer_pack(buf,
"BB",
client_pubkey,
server_pubkey);
if (rc != SSH_OK) {
goto error;
}
break;
#ifdef WITH_GEX
case SSH_KEX_DH_GEX_SHA1:
case SSH_KEX_DH_GEX_SHA256:
rc = ssh_dh_keypair_get_keys(session->next_crypto->dh_ctx,
DH_CLIENT_KEYPAIR, NULL, &client_pubkey);
if (rc != SSH_OK) {
goto error;
}
rc = ssh_dh_keypair_get_keys(session->next_crypto->dh_ctx,
DH_SERVER_KEYPAIR, NULL, &server_pubkey);
if (rc != SSH_OK) {
goto error;
}
rc = ssh_dh_get_parameters(session->next_crypto->dh_ctx,
&modulus, &generator);
if (rc != SSH_OK) {
goto error;
}
rc = ssh_buffer_pack(buf,
"dddBBBB",
session->next_crypto->dh_pmin,
session->next_crypto->dh_pn,
session->next_crypto->dh_pmax,
modulus,
generator,
client_pubkey,
server_pubkey);
if (rc != SSH_OK) {
goto error;
}
break;
#endif /* WITH_GEX */
#ifdef HAVE_ECDH
case SSH_KEX_ECDH_SHA2_NISTP256:
case SSH_KEX_ECDH_SHA2_NISTP384:
case SSH_KEX_ECDH_SHA2_NISTP521:
if (session->next_crypto->ecdh_client_pubkey == NULL ||
session->next_crypto->ecdh_server_pubkey == NULL) {
SSH_LOG(SSH_LOG_WARNING, "ECDH parameted missing");
goto error;
}
rc = ssh_buffer_pack(buf,
"SS",
session->next_crypto->ecdh_client_pubkey,
session->next_crypto->ecdh_server_pubkey);
if (rc != SSH_OK) {
goto error;
}
break;
#endif
#ifdef HAVE_CURVE25519
case SSH_KEX_CURVE25519_SHA256:
case SSH_KEX_CURVE25519_SHA256_LIBSSH_ORG:
rc = ssh_buffer_pack(buf,
"dPdP",
CURVE25519_PUBKEY_SIZE,
(size_t)CURVE25519_PUBKEY_SIZE, session->next_crypto->curve25519_client_pubkey,
CURVE25519_PUBKEY_SIZE,
(size_t)CURVE25519_PUBKEY_SIZE, session->next_crypto->curve25519_server_pubkey);
if (rc != SSH_OK) {
goto error;
}
break;
#endif
}
rc = ssh_buffer_pack(buf, "B", session->next_crypto->shared_secret);
if (rc != SSH_OK) {
goto error;
}
#ifdef DEBUG_CRYPTO
ssh_print_hexa("hash buffer", ssh_buffer_get(buf), ssh_buffer_get_len(buf));
#endif
switch (session->next_crypto->kex_type) {
case SSH_KEX_DH_GROUP1_SHA1:
case SSH_KEX_DH_GROUP14_SHA1:
#ifdef WITH_GEX
case SSH_KEX_DH_GEX_SHA1:
#endif /* WITH_GEX */
session->next_crypto->digest_len = SHA_DIGEST_LENGTH;
session->next_crypto->digest_type = SSH_KDF_SHA1;
session->next_crypto->secret_hash = malloc(session->next_crypto->digest_len);
if (session->next_crypto->secret_hash == NULL) {
ssh_set_error_oom(session);
goto error;
}
sha1(ssh_buffer_get(buf), ssh_buffer_get_len(buf),
session->next_crypto->secret_hash);
break;
case SSH_KEX_ECDH_SHA2_NISTP256:
case SSH_KEX_CURVE25519_SHA256:
case SSH_KEX_CURVE25519_SHA256_LIBSSH_ORG:
#ifdef WITH_GEX
case SSH_KEX_DH_GEX_SHA256:
#endif /* WITH_GEX */
session->next_crypto->digest_len = SHA256_DIGEST_LENGTH;
session->next_crypto->digest_type = SSH_KDF_SHA256;
session->next_crypto->secret_hash = malloc(session->next_crypto->digest_len);
if (session->next_crypto->secret_hash == NULL) {
ssh_set_error_oom(session);
goto error;
}
sha256(ssh_buffer_get(buf), ssh_buffer_get_len(buf),
session->next_crypto->secret_hash);
break;
case SSH_KEX_ECDH_SHA2_NISTP384:
session->next_crypto->digest_len = SHA384_DIGEST_LENGTH;
session->next_crypto->digest_type = SSH_KDF_SHA384;
session->next_crypto->secret_hash = malloc(session->next_crypto->digest_len);
if (session->next_crypto->secret_hash == NULL) {
ssh_set_error_oom(session);
goto error;
}
sha384(ssh_buffer_get(buf), ssh_buffer_get_len(buf),
session->next_crypto->secret_hash);
break;
case SSH_KEX_DH_GROUP16_SHA512:
case SSH_KEX_DH_GROUP18_SHA512:
case SSH_KEX_ECDH_SHA2_NISTP521:
session->next_crypto->digest_len = SHA512_DIGEST_LENGTH;
session->next_crypto->digest_type = SSH_KDF_SHA512;
session->next_crypto->secret_hash = malloc(session->next_crypto->digest_len);
if (session->next_crypto->secret_hash == NULL) {
ssh_set_error_oom(session);
goto error;
}
sha512(ssh_buffer_get(buf),
ssh_buffer_get_len(buf),
session->next_crypto->secret_hash);
break;
}
/* During the first kex, secret hash and session ID are equal. However, after
* a key re-exchange, a new secret hash is calculated. This hash will not replace
* but complement existing session id.
*/
if (!session->next_crypto->session_id) {
session->next_crypto->session_id = malloc(session->next_crypto->digest_len);
if (session->next_crypto->session_id == NULL) {
ssh_set_error_oom(session);
goto error;
}
memcpy(session->next_crypto->session_id, session->next_crypto->secret_hash,
session->next_crypto->digest_len);
}
#ifdef DEBUG_CRYPTO
printf("Session hash: \n");
ssh_print_hexa("secret hash", session->next_crypto->secret_hash, session->next_crypto->digest_len);
ssh_print_hexa("session id", session->next_crypto->session_id, session->next_crypto->digest_len);
#endif
rc = SSH_OK;
error:
ssh_buffer_free(buf);
ssh_buffer_free(client_hash);
ssh_buffer_free(server_hash);
session->in_hashbuf = NULL;
session->out_hashbuf = NULL;
ssh_string_free(num);
return rc;
}
