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openssh/kexdh.c

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/* $OpenBSD: kexdh.c,v 1.34 2020/12/04 02:29:25 djm Exp $ */
/*
* Copyright (c) 2019 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
- deraadt@cvs.openbsd.org 2006/08/03 03:34:42 [OVERVIEW atomicio.c atomicio.h auth-bsdauth.c auth-chall.c auth-krb5.c] [auth-options.c auth-options.h auth-passwd.c auth-rh-rsa.c auth-rhosts.c] [auth-rsa.c auth-skey.c auth.c auth.h auth1.c auth2-chall.c auth2-gss.c] [auth2-hostbased.c auth2-kbdint.c auth2-none.c auth2-passwd.c ] [auth2-pubkey.c auth2.c authfd.c authfd.h authfile.c bufaux.c bufbn.c] [buffer.c buffer.h canohost.c channels.c channels.h cipher-3des1.c] [cipher-bf1.c cipher-ctr.c cipher.c cleanup.c clientloop.c compat.c] [compress.c deattack.c dh.c dispatch.c dns.c dns.h fatal.c groupaccess.c] [groupaccess.h gss-genr.c gss-serv-krb5.c gss-serv.c hostfile.c kex.c] [kex.h kexdh.c kexdhc.c kexdhs.c kexgex.c kexgexc.c kexgexs.c key.c] [key.h log.c log.h mac.c match.c md-sha256.c misc.c misc.h moduli.c] [monitor.c monitor_fdpass.c monitor_mm.c monitor_mm.h monitor_wrap.c] [monitor_wrap.h msg.c nchan.c packet.c progressmeter.c readconf.c] [readconf.h readpass.c rsa.c scard.c scard.h scp.c servconf.c servconf.h] [serverloop.c session.c session.h sftp-client.c sftp-common.c] [sftp-common.h sftp-glob.c sftp-server.c sftp.c ssh-add.c ssh-agent.c] [ssh-dss.c ssh-gss.h ssh-keygen.c ssh-keyscan.c ssh-keysign.c ssh-rsa.c] [ssh.c ssh.h sshconnect.c sshconnect.h sshconnect1.c sshconnect2.c] [sshd.c sshlogin.c sshlogin.h sshpty.c sshpty.h sshtty.c ttymodes.c] [uidswap.c uidswap.h uuencode.c uuencode.h xmalloc.c xmalloc.h] [loginrec.c loginrec.h openbsd-compat/port-aix.c openbsd-compat/port-tun.h] almost entirely get rid of the culture of ".h files that include .h files" ok djm, sort of ok stevesk makes the pain stop in one easy step NB. portable commit contains everything *except* removing includes.h, as that will take a fair bit more work as we move headers that are required for portability workarounds to defines.h. (also, this step wasn't "easy")
2006-08-05 02:39:39 +00:00
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
- deraadt@cvs.openbsd.org 2006/08/03 03:34:42 [OVERVIEW atomicio.c atomicio.h auth-bsdauth.c auth-chall.c auth-krb5.c] [auth-options.c auth-options.h auth-passwd.c auth-rh-rsa.c auth-rhosts.c] [auth-rsa.c auth-skey.c auth.c auth.h auth1.c auth2-chall.c auth2-gss.c] [auth2-hostbased.c auth2-kbdint.c auth2-none.c auth2-passwd.c ] [auth2-pubkey.c auth2.c authfd.c authfd.h authfile.c bufaux.c bufbn.c] [buffer.c buffer.h canohost.c channels.c channels.h cipher-3des1.c] [cipher-bf1.c cipher-ctr.c cipher.c cleanup.c clientloop.c compat.c] [compress.c deattack.c dh.c dispatch.c dns.c dns.h fatal.c groupaccess.c] [groupaccess.h gss-genr.c gss-serv-krb5.c gss-serv.c hostfile.c kex.c] [kex.h kexdh.c kexdhc.c kexdhs.c kexgex.c kexgexc.c kexgexs.c key.c] [key.h log.c log.h mac.c match.c md-sha256.c misc.c misc.h moduli.c] [monitor.c monitor_fdpass.c monitor_mm.c monitor_mm.h monitor_wrap.c] [monitor_wrap.h msg.c nchan.c packet.c progressmeter.c readconf.c] [readconf.h readpass.c rsa.c scard.c scard.h scp.c servconf.c servconf.h] [serverloop.c session.c session.h sftp-client.c sftp-common.c] [sftp-common.h sftp-glob.c sftp-server.c sftp.c ssh-add.c ssh-agent.c] [ssh-dss.c ssh-gss.h ssh-keygen.c ssh-keyscan.c ssh-keysign.c ssh-rsa.c] [ssh.c ssh.h sshconnect.c sshconnect.h sshconnect1.c sshconnect2.c] [sshd.c sshlogin.c sshlogin.h sshpty.c sshpty.h sshtty.c ttymodes.c] [uidswap.c uidswap.h uuencode.c uuencode.h xmalloc.c xmalloc.h] [loginrec.c loginrec.h openbsd-compat/port-aix.c openbsd-compat/port-tun.h] almost entirely get rid of the culture of ".h files that include .h files" ok djm, sort of ok stevesk makes the pain stop in one easy step NB. portable commit contains everything *except* removing includes.h, as that will take a fair bit more work as we move headers that are required for portability workarounds to defines.h. (also, this step wasn't "easy")
2006-08-05 02:39:39 +00:00
2019-01-21 23:49:52 +00:00
#include "openbsd-compat/openssl-compat.h"
2019-01-21 23:50:40 +00:00
#include <openssl/dh.h>
2019-01-21 23:49:52 +00:00
#include "sshkey.h"
#include "kex.h"
#include "sshbuf.h"
#include "digest.h"
2019-01-21 12:11:21 +00:00
#include "ssherr.h"
#include "dh.h"
#include "log.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_keypair(struct kex *kex)
{
const BIGNUM *pub_key;
struct sshbuf *buf = NULL;
int r;
if ((r = kex_dh_keygen(kex)) != 0)
return r;
DH_get0_key(kex->dh, &pub_key, NULL);
if ((buf = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_bignum2(buf, pub_key)) != 0 ||
(r = sshbuf_get_u32(buf, NULL)) != 0)
goto out;
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, kex->dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, pub_key);
fprintf(stderr, "\n");
#endif
kex->client_pub = buf;
buf = NULL;
out:
sshbuf_free(buf);
return r;
}
int
kex_dh_enc(struct kex *kex, const struct sshbuf *client_blob,
struct sshbuf **server_blobp, struct sshbuf **shared_secretp)
{
const BIGNUM *pub_key;
struct sshbuf *server_blob = NULL;
int r;
*server_blobp = NULL;
*shared_secretp = NULL;
if ((r = kex_dh_keygen(kex)) != 0)
goto out;
DH_get0_key(kex->dh, &pub_key, NULL);
if ((server_blob = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = sshbuf_put_bignum2(server_blob, pub_key)) != 0 ||
(r = sshbuf_get_u32(server_blob, NULL)) != 0)
goto out;
if ((r = kex_dh_dec(kex, client_blob, shared_secretp)) != 0)
goto out;
*server_blobp = server_blob;
server_blob = NULL;
out:
DH_free(kex->dh);
kex->dh = NULL;
sshbuf_free(server_blob);
return r;
}
int
kex_dh_dec(struct kex *kex, const struct sshbuf *dh_blob,
struct sshbuf **shared_secretp)
{
struct sshbuf *buf = NULL;
BIGNUM *dh_pub = NULL;
int r;
*shared_secretp = NULL;
if ((buf = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = sshbuf_put_stringb(buf, dh_blob)) != 0 ||
(r = sshbuf_get_bignum2(buf, &dh_pub)) != 0)
goto out;
sshbuf_reset(buf);
if ((r = kex_dh_compute_key(kex, dh_pub, buf)) != 0)
goto out;
*shared_secretp = buf;
buf = NULL;
out:
BN_free(dh_pub);
DH_free(kex->dh);
kex->dh = NULL;
sshbuf_free(buf);
return r;
}
#endif /* WITH_OPENSSL */