| /* $OpenBSD: kexdh.c,v 1.29 2019/01/21 10:03:37 djm 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 <signal.h> |
| |
| #include <openssl/evp.h> |
| |
| #include "openbsd-compat/openssl-compat.h" |
| |
| #include "ssh2.h" |
| #include "sshkey.h" |
| #include "cipher.h" |
| #include "kex.h" |
| #include "dh.h" |
| #include "ssherr.h" |
| #include "sshbuf.h" |
| #include "digest.h" |
| #include "dh.h" |
| |
| int |
| kex_dh_keygen(struct kex *kex) |
| { |
| 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: |
| return SSH_ERR_INVALID_ARGUMENT; |
| } |
| if (kex->dh == NULL) |
| return SSH_ERR_ALLOC_FAIL; |
| return (dh_gen_key(kex->dh, kex->we_need * 8)); |
| } |
| |
| int |
| kex_dh_compute_key(struct kex *kex, BIGNUM *dh_pub, struct sshbuf *out) |
| { |
| BIGNUM *shared_secret = NULL; |
| u_char *kbuf = NULL; |
| size_t klen = 0; |
| int kout, r; |
| |
| #ifdef DEBUG_KEXDH |
| fprintf(stderr, "dh_pub= "); |
| BN_print_fp(stderr, dh_pub); |
| fprintf(stderr, "\n"); |
| debug("bits %d", BN_num_bits(dh_pub)); |
| DHparams_print_fp(stderr, kex->dh); |
| fprintf(stderr, "\n"); |
| #endif |
| |
| if (!dh_pub_is_valid(kex->dh, dh_pub)) { |
| 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_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 |
| r = sshbuf_put_bignum2(out, shared_secret); |
| out: |
| freezero(kbuf, klen); |
| BN_clear_free(shared_secret); |
| return r; |
| } |
| |
| int |
| kex_dh_hash( |
| int hash_alg, |
| const struct sshbuf *client_version, |
| const struct sshbuf *server_version, |
| const u_char *ckexinit, size_t ckexinitlen, |
| const u_char *skexinit, size_t skexinitlen, |
| const u_char *serverhostkeyblob, size_t sbloblen, |
| const BIGNUM *client_dh_pub, |
| const BIGNUM *server_dh_pub, |
| const u_char *shared_secret, size_t secretlen, |
| u_char *hash, size_t *hashlen) |
| { |
| struct sshbuf *b; |
| int r; |
| |
| if (*hashlen < ssh_digest_bytes(hash_alg)) |
| return SSH_ERR_INVALID_ARGUMENT; |
| if ((b = sshbuf_new()) == NULL) |
| return SSH_ERR_ALLOC_FAIL; |
| if ((r = sshbuf_put_stringb(b, client_version)) < 0 || |
| (r = sshbuf_put_stringb(b, server_version)) < 0 || |
| /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ |
| (r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 || |
| (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 || |
| (r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 || |
| (r = sshbuf_put_u32(b, skexinitlen+1)) != 0 || |
| (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 || |
| (r = sshbuf_put(b, skexinit, skexinitlen)) != 0 || |
| (r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 || |
| (r = sshbuf_put_bignum2(b, client_dh_pub)) != 0 || |
| (r = sshbuf_put_bignum2(b, server_dh_pub)) != 0 || |
| (r = sshbuf_put(b, shared_secret, secretlen)) != 0) { |
| sshbuf_free(b); |
| return r; |
| } |
| #ifdef DEBUG_KEX |
| sshbuf_dump(b, stderr); |
| #endif |
| if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) { |
| sshbuf_free(b); |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| } |
| sshbuf_free(b); |
| *hashlen = ssh_digest_bytes(hash_alg); |
| #ifdef DEBUG_KEX |
| dump_digest("hash", hash, *hashlen); |
| #endif |
| return 0; |
| } |
| #endif /* WITH_OPENSSL */ |