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kexgexs.c
/* $OpenBSD: kexgexs.c,v 1.35 2018/10/04 00:04:41 djm Exp $ */ | /* $OpenBSD: kexgexs.c,v 1.42 2019/01/23 00:30:41 djm Exp $ */ | ||||
/* | /* | ||||
* Copyright (c) 2000 Niels Provos. All rights reserved. | * Copyright (c) 2000 Niels Provos. All rights reserved. | ||||
* Copyright (c) 2001 Markus Friedl. All rights reserved. | * Copyright (c) 2001 Markus Friedl. All rights reserved. | ||||
* | * | ||||
* Redistribution and use in source and binary forms, with or without | * Redistribution and use in source and binary forms, with or without | ||||
* modification, are permitted provided that the following conditions | * modification, are permitted provided that the following conditions | ||||
* are met: | * are met: | ||||
* 1. Redistributions of source code must retain the above copyright | * 1. Redistributions of source code must retain the above copyright | ||||
▲ Show 20 Lines • Show All 111 Lines • ▼ Show 20 Lines | |||||
out: | out: | ||||
return r; | return r; | ||||
} | } | ||||
static int | static int | ||||
input_kex_dh_gex_init(int type, u_int32_t seq, struct ssh *ssh) | input_kex_dh_gex_init(int type, u_int32_t seq, struct ssh *ssh) | ||||
{ | { | ||||
struct kex *kex = ssh->kex; | struct kex *kex = ssh->kex; | ||||
BIGNUM *shared_secret = NULL, *dh_client_pub = NULL; | BIGNUM *dh_client_pub = NULL; | ||||
const BIGNUM *pub_key, *dh_p, *dh_g; | const BIGNUM *pub_key, *dh_p, *dh_g; | ||||
struct sshbuf *shared_secret = NULL; | |||||
struct sshbuf *server_host_key_blob = NULL; | |||||
struct sshkey *server_host_public, *server_host_private; | struct sshkey *server_host_public, *server_host_private; | ||||
u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL; | u_char *signature = NULL; | ||||
u_char hash[SSH_DIGEST_MAX_LENGTH]; | u_char hash[SSH_DIGEST_MAX_LENGTH]; | ||||
size_t sbloblen, slen; | size_t slen, hashlen; | ||||
size_t klen = 0, hashlen; | int r; | ||||
int kout, r; | |||||
if (kex->load_host_public_key == NULL || | if ((r = kex_load_hostkey(ssh, &server_host_private, | ||||
kex->load_host_private_key == NULL) { | &server_host_public)) != 0) | ||||
r = SSH_ERR_INVALID_ARGUMENT; | |||||
goto out; | goto out; | ||||
} | |||||
server_host_public = kex->load_host_public_key(kex->hostkey_type, | |||||
kex->hostkey_nid, ssh); | |||||
server_host_private = kex->load_host_private_key(kex->hostkey_type, | |||||
kex->hostkey_nid, ssh); | |||||
if (server_host_public == NULL) { | |||||
r = SSH_ERR_NO_HOSTKEY_LOADED; | |||||
goto out; | |||||
} | |||||
/* key, cert */ | /* key, cert */ | ||||
if ((dh_client_pub = BN_new()) == NULL) { | if ((r = sshpkt_get_bignum2(ssh, &dh_client_pub)) != 0 || | ||||
r = SSH_ERR_ALLOC_FAIL; | |||||
goto out; | |||||
} | |||||
if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 || | |||||
(r = sshpkt_get_end(ssh)) != 0) | (r = sshpkt_get_end(ssh)) != 0) | ||||
goto out; | goto out; | ||||
if ((shared_secret = sshbuf_new()) == NULL) { | |||||
DH_get0_key(kex->dh, &pub_key, NULL); | r = SSH_ERR_ALLOC_FAIL; | ||||
DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g); | |||||
#ifdef DEBUG_KEXDH | |||||
fprintf(stderr, "dh_client_pub= "); | |||||
BN_print_fp(stderr, dh_client_pub); | |||||
fprintf(stderr, "\n"); | |||||
debug("bits %d", BN_num_bits(dh_client_pub)); | |||||
DHparams_print_fp(stderr, kex->dh); | |||||
fprintf(stderr, "pub= "); | |||||
BN_print_fp(stderr, pub_key); | |||||
fprintf(stderr, "\n"); | |||||
#endif | |||||
if (!dh_pub_is_valid(kex->dh, dh_client_pub)) { | |||||
sshpkt_disconnect(ssh, "bad client public DH value"); | |||||
r = SSH_ERR_MESSAGE_INCOMPLETE; | |||||
goto out; | goto out; | ||||
} | } | ||||
if ((r = kex_dh_compute_key(kex, dh_client_pub, shared_secret)) != 0) | |||||
klen = DH_size(kex->dh); | goto out; | ||||
if ((kbuf = malloc(klen)) == NULL || | if ((server_host_key_blob = sshbuf_new()) == NULL) { | ||||
(shared_secret = BN_new()) == NULL) { | |||||
r = SSH_ERR_ALLOC_FAIL; | r = SSH_ERR_ALLOC_FAIL; | ||||
goto out; | goto out; | ||||
} | } | ||||
if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 || | if ((r = sshkey_putb(server_host_public, server_host_key_blob)) != 0) | ||||
BN_bin2bn(kbuf, kout, shared_secret) == NULL) { | |||||
r = SSH_ERR_LIBCRYPTO_ERROR; | |||||
goto out; | goto out; | ||||
} | |||||
#ifdef DEBUG_KEXDH | |||||
dump_digest("shared secret", kbuf, kout); | |||||
#endif | |||||
if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob, | |||||
&sbloblen)) != 0) | |||||
goto out; | |||||
/* calc H */ | /* calc H */ | ||||
DH_get0_key(kex->dh, &pub_key, NULL); | |||||
DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g); | |||||
hashlen = sizeof(hash); | hashlen = sizeof(hash); | ||||
if ((r = kexgex_hash( | if ((r = kexgex_hash( | ||||
kex->hash_alg, | kex->hash_alg, | ||||
kex->client_version_string, | kex->client_version, | ||||
kex->server_version_string, | kex->server_version, | ||||
sshbuf_ptr(kex->peer), sshbuf_len(kex->peer), | kex->peer, | ||||
sshbuf_ptr(kex->my), sshbuf_len(kex->my), | kex->my, | ||||
server_host_key_blob, sbloblen, | server_host_key_blob, | ||||
kex->min, kex->nbits, kex->max, | kex->min, kex->nbits, kex->max, | ||||
dh_p, dh_g, | dh_p, dh_g, | ||||
dh_client_pub, | dh_client_pub, | ||||
pub_key, | pub_key, | ||||
shared_secret, | sshbuf_ptr(shared_secret), sshbuf_len(shared_secret), | ||||
hash, &hashlen)) != 0) | hash, &hashlen)) != 0) | ||||
goto out; | goto out; | ||||
/* save session id := H */ | |||||
if (kex->session_id == NULL) { | |||||
kex->session_id_len = hashlen; | |||||
kex->session_id = malloc(kex->session_id_len); | |||||
if (kex->session_id == NULL) { | |||||
r = SSH_ERR_ALLOC_FAIL; | |||||
goto out; | |||||
} | |||||
memcpy(kex->session_id, hash, kex->session_id_len); | |||||
} | |||||
/* sign H */ | /* sign H */ | ||||
if ((r = kex->sign(server_host_private, server_host_public, &signature, | if ((r = kex->sign(ssh, server_host_private, server_host_public, | ||||
&slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0) | &signature, &slen, hash, hashlen, kex->hostkey_alg)) < 0) | ||||
goto out; | goto out; | ||||
/* destroy_sensitive_data(); */ | |||||
/* send server hostkey, DH pubkey 'f' and signed H */ | /* send server hostkey, DH pubkey 'f' and signed H */ | ||||
if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REPLY)) != 0 || | if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REPLY)) != 0 || | ||||
(r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 || | (r = sshpkt_put_stringb(ssh, server_host_key_blob)) != 0 || | ||||
(r = sshpkt_put_bignum2(ssh, pub_key)) != 0 || /* f */ | (r = sshpkt_put_bignum2(ssh, pub_key)) != 0 || /* f */ | ||||
(r = sshpkt_put_string(ssh, signature, slen)) != 0 || | (r = sshpkt_put_string(ssh, signature, slen)) != 0 || | ||||
(r = sshpkt_send(ssh)) != 0) | (r = sshpkt_send(ssh)) != 0) | ||||
goto out; | goto out; | ||||
if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0) | if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) | ||||
r = kex_send_newkeys(ssh); | r = kex_send_newkeys(ssh); | ||||
out: | out: | ||||
explicit_bzero(hash, sizeof(hash)); | explicit_bzero(hash, sizeof(hash)); | ||||
DH_free(kex->dh); | DH_free(kex->dh); | ||||
kex->dh = NULL; | kex->dh = NULL; | ||||
BN_clear_free(dh_client_pub); | BN_clear_free(dh_client_pub); | ||||
if (kbuf) { | sshbuf_free(shared_secret); | ||||
explicit_bzero(kbuf, klen); | sshbuf_free(server_host_key_blob); | ||||
free(kbuf); | |||||
} | |||||
BN_clear_free(shared_secret); | |||||
free(server_host_key_blob); | |||||
free(signature); | free(signature); | ||||
return r; | return r; | ||||
} | } | ||||
#endif /* WITH_OPENSSL */ | #endif /* WITH_OPENSSL */ |