-/* $OpenBSD: kexgexc.c,v 1.12 2010/11/10 01:33:07 djm Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.20 2015/01/26 06:10:03 djm Exp $ */
/*
* Copyright (c) 2000 Niels Provos. All rights reserved.
* Copyright (c) 2001 Markus Friedl. All rights reserved.
#include "includes.h"
+#ifdef WITH_OPENSSL
+
#include <sys/types.h>
#include <openssl/dh.h>
#include <string.h>
#include <signal.h>
-#include "xmalloc.h"
-#include "buffer.h"
-#include "key.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 "compat.h"
+#include "dispatch.h"
+#include "ssherr.h"
+#include "sshbuf.h"
+
+static int input_kex_dh_gex_group(int, u_int32_t, void *);
+static int input_kex_dh_gex_reply(int, u_int32_t, void *);
-void
-kexgex_client(Kex *kex)
+int
+kexgex_client(struct ssh *ssh)
{
- BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
- BIGNUM *p = NULL, *g = NULL;
- Key *server_host_key;
- u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
- u_int klen, slen, sbloblen, hashlen;
- int kout;
- int min, max, nbits;
- DH *dh;
+ struct kex *kex = ssh->kex;
+ int r;
+ u_int nbits;
- nbits = dh_estimate(kex->we_need * 8);
+ nbits = dh_estimate(kex->dh_need * 8);
- if (datafellows & SSH_OLD_DHGEX) {
+ kex->min = DH_GRP_MIN;
+ kex->max = DH_GRP_MAX;
+ kex->nbits = nbits;
+ if (ssh->compat & SSH_OLD_DHGEX) {
/* Old GEX request */
- packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
- packet_put_int(nbits);
- min = DH_GRP_MIN;
- max = DH_GRP_MAX;
-
- debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits);
+ if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST_OLD))
+ != 0 ||
+ (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0)
+ goto out;
+ debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", kex->nbits);
} else {
/* New GEX request */
- min = DH_GRP_MIN;
- max = DH_GRP_MAX;
- packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
- packet_put_int(min);
- packet_put_int(nbits);
- packet_put_int(max);
-
+ if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST)) != 0 ||
+ (r = sshpkt_put_u32(ssh, kex->min)) != 0 ||
+ (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
+ (r = sshpkt_put_u32(ssh, kex->max)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0)
+ goto out;
debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
- min, nbits, max);
+ kex->min, kex->nbits, kex->max);
}
#ifdef DEBUG_KEXDH
fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
- min, nbits, max);
+ kex->min, kex->nbits, kex->max);
#endif
- packet_send();
-
- debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
- packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);
+ ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP,
+ &input_kex_dh_gex_group);
+ r = 0;
+ out:
+ return r;
+}
- if ((p = BN_new()) == NULL)
- fatal("BN_new");
- packet_get_bignum2(p);
- if ((g = BN_new()) == NULL)
- fatal("BN_new");
- packet_get_bignum2(g);
- packet_check_eom();
+static int
+input_kex_dh_gex_group(int type, u_int32_t seq, void *ctxt)
+{
+ struct ssh *ssh = ctxt;
+ struct kex *kex = ssh->kex;
+ BIGNUM *p = NULL, *g = NULL;
+ int r, bits;
- if (BN_num_bits(p) < min || BN_num_bits(p) > max)
- fatal("DH_GEX group out of range: %d !< %d !< %d",
- min, BN_num_bits(p), max);
+ debug("got SSH2_MSG_KEX_DH_GEX_GROUP");
- dh = dh_new_group(g, p);
- dh_gen_key(dh, kex->we_need * 8);
+ if ((p = BN_new()) == NULL ||
+ (g = BN_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((r = sshpkt_get_bignum2(ssh, p)) != 0 ||
+ (r = sshpkt_get_bignum2(ssh, g)) != 0 ||
+ (r = sshpkt_get_end(ssh)) != 0)
+ goto out;
+ if ((bits = BN_num_bits(p)) < 0 ||
+ (u_int)bits < kex->min || (u_int)bits > kex->max) {
+ r = SSH_ERR_DH_GEX_OUT_OF_RANGE;
+ goto out;
+ }
+ if ((kex->dh = dh_new_group(g, p)) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ p = g = NULL; /* belong to kex->dh now */
+ /* generate and send 'e', client DH public key */
+ if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0 ||
+ (r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_INIT)) != 0 ||
+ (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0)
+ goto out;
+ debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
#ifdef DEBUG_KEXDH
- DHparams_print_fp(stderr, dh);
+ DHparams_print_fp(stderr, kex->dh);
fprintf(stderr, "pub= ");
- BN_print_fp(stderr, dh->pub_key);
+ BN_print_fp(stderr, kex->dh->pub_key);
fprintf(stderr, "\n");
#endif
+ ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP, NULL);
+ ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REPLY, &input_kex_dh_gex_reply);
+ r = 0;
+out:
+ if (p)
+ BN_clear_free(p);
+ if (g)
+ BN_clear_free(g);
+ return r;
+}
- debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
- /* generate and send 'e', client DH public key */
- packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
- packet_put_bignum2(dh->pub_key);
- packet_send();
-
- debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
- packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);
+static int
+input_kex_dh_gex_reply(int type, u_int32_t seq, void *ctxt)
+{
+ struct ssh *ssh = ctxt;
+ struct kex *kex = ssh->kex;
+ BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
+ struct sshkey *server_host_key = NULL;
+ u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
+ u_char hash[SSH_DIGEST_MAX_LENGTH];
+ size_t klen = 0, slen, sbloblen, hashlen;
+ int kout, r;
+ debug("got SSH2_MSG_KEX_DH_GEX_REPLY");
+ if (kex->verify_host_key == NULL) {
+ r = SSH_ERR_INVALID_ARGUMENT;
+ goto out;
+ }
/* key, cert */
- server_host_key_blob = packet_get_string(&sbloblen);
- server_host_key = key_from_blob(server_host_key_blob, sbloblen);
- if (server_host_key == NULL)
- fatal("cannot decode server_host_key_blob");
- if (server_host_key->type != kex->hostkey_type)
- fatal("type mismatch for decoded server_host_key_blob");
- if (kex->verify_host_key == NULL)
- fatal("cannot verify server_host_key");
- if (kex->verify_host_key(server_host_key) == -1)
- fatal("server_host_key verification failed");
-
+ if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
+ &sbloblen)) != 0 ||
+ (r = sshkey_from_blob(server_host_key_blob, sbloblen,
+ &server_host_key)) != 0)
+ goto out;
+ if (server_host_key->type != kex->hostkey_type) {
+ r = SSH_ERR_KEY_TYPE_MISMATCH;
+ goto out;
+ }
+ if (server_host_key->type != kex->hostkey_type ||
+ (kex->hostkey_type == KEY_ECDSA &&
+ server_host_key->ecdsa_nid != kex->hostkey_nid)) {
+ r = SSH_ERR_KEY_TYPE_MISMATCH;
+ goto out;
+ }
+ if (kex->verify_host_key(server_host_key, ssh) == -1) {
+ r = SSH_ERR_SIGNATURE_INVALID;
+ goto out;
+ }
/* DH parameter f, server public DH key */
- if ((dh_server_pub = BN_new()) == NULL)
- fatal("dh_server_pub == NULL");
- packet_get_bignum2(dh_server_pub);
-
+ if ((dh_server_pub = BN_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ /* signed H */
+ if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 ||
+ (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
+ (r = sshpkt_get_end(ssh)) != 0)
+ goto out;
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_server_pub= ");
BN_print_fp(stderr, dh_server_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_server_pub));
#endif
+ if (!dh_pub_is_valid(kex->dh, dh_server_pub)) {
+ sshpkt_disconnect(ssh, "bad server public DH value");
+ r = SSH_ERR_MESSAGE_INCOMPLETE;
+ goto out;
+ }
- /* signed H */
- signature = packet_get_string(&slen);
- packet_check_eom();
-
- if (!dh_pub_is_valid(dh, dh_server_pub))
- packet_disconnect("bad server public DH value");
-
- klen = DH_size(dh);
- kbuf = xmalloc(klen);
- if ((kout = DH_compute_key(kbuf, dh_server_pub, dh)) < 0)
- fatal("DH_compute_key: failed");
+ 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_server_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 ((shared_secret = BN_new()) == NULL)
- fatal("kexgex_client: BN_new failed");
- if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
- fatal("kexgex_client: BN_bin2bn failed");
- memset(kbuf, 0, klen);
- xfree(kbuf);
-
- if (datafellows & SSH_OLD_DHGEX)
- min = max = -1;
+ if (ssh->compat & SSH_OLD_DHGEX)
+ kex->min = kex->max = -1;
/* calc and verify H */
- kexgex_hash(
- kex->evp_md,
+ hashlen = sizeof(hash);
+ if ((r = kexgex_hash(
+ kex->hash_alg,
kex->client_version_string,
kex->server_version_string,
- buffer_ptr(&kex->my), buffer_len(&kex->my),
- buffer_ptr(&kex->peer), buffer_len(&kex->peer),
+ sshbuf_ptr(kex->my), sshbuf_len(kex->my),
+ sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
server_host_key_blob, sbloblen,
- min, nbits, max,
- dh->p, dh->g,
- dh->pub_key,
+ kex->min, kex->nbits, kex->max,
+ kex->dh->p, kex->dh->g,
+ kex->dh->pub_key,
dh_server_pub,
shared_secret,
- &hash, &hashlen
- );
+ hash, &hashlen)) != 0)
+ goto out;
- /* have keys, free DH */
- DH_free(dh);
- xfree(server_host_key_blob);
- BN_clear_free(dh_server_pub);
-
- if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
- fatal("key_verify failed for server_host_key");
- key_free(server_host_key);
- xfree(signature);
+ if ((r = sshkey_verify(server_host_key, signature, slen, hash,
+ hashlen, ssh->compat)) != 0)
+ goto out;
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
- kex->session_id = xmalloc(kex->session_id_len);
+ 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);
}
- kex_derive_keys(kex, hash, hashlen, shared_secret);
- BN_clear_free(shared_secret);
- kex_finish(kex);
+ 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_server_pub)
+ BN_clear_free(dh_server_pub);
+ if (kbuf) {
+ explicit_bzero(kbuf, klen);
+ free(kbuf);
+ }
+ if (shared_secret)
+ BN_clear_free(shared_secret);
+ sshkey_free(server_host_key);
+ free(server_host_key_blob);
+ free(signature);
+ return r;
}
+#endif /* WITH_OPENSSL */
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