| /* $OpenBSD: kexdhs.c,v 1.25 2017/05/30 14:23:52 markus Exp $ */ |
| /* |
| * Copyright (c) 2001 Markus Friedl. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. 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. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. |
| */ |
| |
| #include "includes.h" |
| |
| #ifdef WITH_OPENSSL |
| |
| #include <sys/types.h> |
| |
| #include <stdarg.h> |
| #include <string.h> |
| #include <signal.h> |
| |
| #include <openssl/dh.h> |
| |
| #include "sshkey.h" |
| #include "cipher.h" |
| #include "digest.h" |
| #include "kex.h" |
| #include "log.h" |
| #include "packet.h" |
| #include "dh.h" |
| #include "ssh2.h" |
| |
| #include "dispatch.h" |
| #include "compat.h" |
| #include "ssherr.h" |
| #include "sshbuf.h" |
| |
| static int input_kex_dh_init(int, u_int32_t, struct ssh *); |
| |
| int |
| kexdh_server(struct ssh *ssh) |
| { |
| struct kex *kex = ssh->kex; |
| int r; |
| |
| /* generate server DH public key */ |
| switch (kex->kex_type) { |
| case KEX_DH_GRP1_SHA1: |
| kex->dh = dh_new_group1(); |
| break; |
| case KEX_DH_GRP14_SHA1: |
| case KEX_DH_GRP14_SHA256: |
| kex->dh = dh_new_group14(); |
| break; |
| case KEX_DH_GRP16_SHA512: |
| kex->dh = dh_new_group16(); |
| break; |
| case KEX_DH_GRP18_SHA512: |
| kex->dh = dh_new_group18(); |
| break; |
| default: |
| r = SSH_ERR_INVALID_ARGUMENT; |
| goto out; |
| } |
| if (kex->dh == NULL) { |
| r = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0) |
| goto out; |
| |
| debug("expecting SSH2_MSG_KEXDH_INIT"); |
| ssh_dispatch_set(ssh, SSH2_MSG_KEXDH_INIT, &input_kex_dh_init); |
| r = 0; |
| out: |
| return r; |
| } |
| |
| int |
| input_kex_dh_init(int type, u_int32_t seq, struct ssh *ssh) |
| { |
| struct kex *kex = ssh->kex; |
| BIGNUM *shared_secret = NULL, *dh_client_pub = NULL; |
| struct sshkey *server_host_public, *server_host_private; |
| u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL; |
| u_char hash[SSH_DIGEST_MAX_LENGTH]; |
| size_t sbloblen, slen; |
| size_t klen = 0, hashlen; |
| int kout, r; |
| |
| if (kex->load_host_public_key == NULL || |
| kex->load_host_private_key == NULL) { |
| r = SSH_ERR_INVALID_ARGUMENT; |
| 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 */ |
| if ((dh_client_pub = BN_new()) == NULL) { |
| r = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 || |
| (r = sshpkt_get_end(ssh)) != 0) |
| goto out; |
| |
| #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)); |
| #endif |
| |
| #ifdef DEBUG_KEXDH |
| DHparams_print_fp(stderr, kex->dh); |
| fprintf(stderr, "pub= "); |
| BN_print_fp(stderr, kex->dh->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; |
| } |
| |
| klen = DH_size(kex->dh); |
| if ((kbuf = malloc(klen)) == NULL || |
| (shared_secret = BN_new()) == NULL) { |
| r = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 || |
| BN_bin2bn(kbuf, kout, shared_secret) == NULL) { |
| r = SSH_ERR_LIBCRYPTO_ERROR; |
| 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 */ |
| hashlen = sizeof(hash); |
| if ((r = kex_dh_hash( |
| kex->hash_alg, |
| kex->client_version_string, |
| kex->server_version_string, |
| sshbuf_ptr(kex->peer), sshbuf_len(kex->peer), |
| sshbuf_ptr(kex->my), sshbuf_len(kex->my), |
| server_host_key_blob, sbloblen, |
| dh_client_pub, |
| kex->dh->pub_key, |
| shared_secret, |
| hash, &hashlen)) != 0) |
| 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 */ |
| if ((r = kex->sign(server_host_private, server_host_public, &signature, |
| &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0) |
| goto out; |
| |
| /* destroy_sensitive_data(); */ |
| |
| /* send server hostkey, DH pubkey 'f' and singed H */ |
| if ((r = sshpkt_start(ssh, SSH2_MSG_KEXDH_REPLY)) != 0 || |
| (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 || |
| (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 || /* f */ |
| (r = sshpkt_put_string(ssh, signature, slen)) != 0 || |
| (r = sshpkt_send(ssh)) != 0) |
| goto out; |
| |
| if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0) |
| r = kex_send_newkeys(ssh); |
| out: |
| explicit_bzero(hash, sizeof(hash)); |
| DH_free(kex->dh); |
| kex->dh = NULL; |
| if (dh_client_pub) |
| BN_clear_free(dh_client_pub); |
| if (kbuf) { |
| explicit_bzero(kbuf, klen); |
| free(kbuf); |
| } |
| if (shared_secret) |
| BN_clear_free(shared_secret); |
| free(server_host_key_blob); |
| free(signature); |
| return r; |
| } |
| #endif /* WITH_OPENSSL */ |