1 /* $OpenBSD: kex.c,v 1.127 2016/10/10 19:28:48 markus Exp $ */
3 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 #include <openssl/crypto.h>
37 #include <openssl/dh.h>
57 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
58 # if defined(HAVE_EVP_SHA256)
59 # define evp_ssh_sha256 EVP_sha256
61 extern const EVP_MD *evp_ssh_sha256(void);
66 static int kex_choose_conf(struct ssh *);
67 static int kex_input_newkeys(int, u_int32_t, void *);
69 static const char *proposal_names[PROPOSAL_MAX] = {
71 "host key algorithms",
88 static const struct kexalg kexalgs[] = {
90 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
91 { KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
92 { KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
93 { KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
94 { KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
95 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
96 #ifdef HAVE_EVP_SHA256
97 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
98 #endif /* HAVE_EVP_SHA256 */
99 #ifdef OPENSSL_HAS_ECC
100 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
101 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
102 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
104 # ifdef OPENSSL_HAS_NISTP521
105 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
107 # endif /* OPENSSL_HAS_NISTP521 */
108 #endif /* OPENSSL_HAS_ECC */
109 #endif /* WITH_OPENSSL */
110 #if defined(HAVE_EVP_SHA256) || !defined(WITH_OPENSSL)
111 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
112 { KEX_CURVE25519_SHA256_OLD, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
113 #endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */
118 kex_alg_list(char sep)
120 char *ret = NULL, *tmp;
121 size_t nlen, rlen = 0;
122 const struct kexalg *k;
124 for (k = kexalgs; k->name != NULL; k++) {
127 nlen = strlen(k->name);
128 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
133 memcpy(ret + rlen, k->name, nlen + 1);
139 static const struct kexalg *
140 kex_alg_by_name(const char *name)
142 const struct kexalg *k;
144 for (k = kexalgs; k->name != NULL; k++) {
145 if (strcmp(k->name, name) == 0)
151 /* Validate KEX method name list */
153 kex_names_valid(const char *names)
157 if (names == NULL || strcmp(names, "") == 0)
159 if ((s = cp = strdup(names)) == NULL)
161 for ((p = strsep(&cp, ",")); p && *p != '\0';
162 (p = strsep(&cp, ","))) {
163 if (kex_alg_by_name(p) == NULL) {
164 error("Unsupported KEX algorithm \"%.100s\"", p);
169 debug3("kex names ok: [%s]", names);
175 * Concatenate algorithm names, avoiding duplicates in the process.
176 * Caller must free returned string.
179 kex_names_cat(const char *a, const char *b)
181 char *ret = NULL, *tmp = NULL, *cp, *p;
184 if (a == NULL || *a == '\0')
186 if (b == NULL || *b == '\0')
188 if (strlen(b) > 1024*1024)
190 len = strlen(a) + strlen(b) + 2;
191 if ((tmp = cp = strdup(b)) == NULL ||
192 (ret = calloc(1, len)) == NULL) {
196 strlcpy(ret, a, len);
197 for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
198 if (match_list(ret, p, NULL) != NULL)
199 continue; /* Algorithm already present */
200 if (strlcat(ret, ",", len) >= len ||
201 strlcat(ret, p, len) >= len) {
204 return NULL; /* Shouldn't happen */
212 * Assemble a list of algorithms from a default list and a string from a
213 * configuration file. The user-provided string may begin with '+' to
214 * indicate that it should be appended to the default.
217 kex_assemble_names(const char *def, char **list)
221 if (list == NULL || *list == NULL || **list == '\0') {
229 if ((ret = kex_names_cat(def, *list + 1)) == NULL)
230 return SSH_ERR_ALLOC_FAIL;
236 /* put algorithm proposal into buffer */
238 kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
246 * add a dummy cookie, the cookie will be overwritten by
247 * kex_send_kexinit(), each time a kexinit is set
249 for (i = 0; i < KEX_COOKIE_LEN; i++) {
250 if ((r = sshbuf_put_u8(b, 0)) != 0)
253 for (i = 0; i < PROPOSAL_MAX; i++) {
254 if ((r = sshbuf_put_cstring(b, proposal[i])) != 0)
257 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* first_kex_packet_follows */
258 (r = sshbuf_put_u32(b, 0)) != 0) /* uint32 reserved */
263 /* parse buffer and return algorithm proposal */
265 kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
267 struct sshbuf *b = NULL;
270 char **proposal = NULL;
274 if ((proposal = calloc(PROPOSAL_MAX, sizeof(char *))) == NULL)
275 return SSH_ERR_ALLOC_FAIL;
276 if ((b = sshbuf_fromb(raw)) == NULL) {
277 r = SSH_ERR_ALLOC_FAIL;
280 if ((r = sshbuf_consume(b, KEX_COOKIE_LEN)) != 0) /* skip cookie */
282 /* extract kex init proposal strings */
283 for (i = 0; i < PROPOSAL_MAX; i++) {
284 if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0)
286 debug2("%s: %s", proposal_names[i], proposal[i]);
288 /* first kex follows / reserved */
289 if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
290 (r = sshbuf_get_u32(b, &i)) != 0) /* reserved */
292 if (first_kex_follows != NULL)
293 *first_kex_follows = v;
294 debug2("first_kex_follows %d ", v);
295 debug2("reserved %u ", i);
299 if (r != 0 && proposal != NULL)
300 kex_prop_free(proposal);
306 kex_prop_free(char **proposal)
310 if (proposal == NULL)
312 for (i = 0; i < PROPOSAL_MAX; i++)
319 kex_protocol_error(int type, u_int32_t seq, void *ctxt)
321 struct ssh *ssh = active_state; /* XXX */
324 error("kex protocol error: type %d seq %u", type, seq);
325 if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
326 (r = sshpkt_put_u32(ssh, seq)) != 0 ||
327 (r = sshpkt_send(ssh)) != 0)
333 kex_reset_dispatch(struct ssh *ssh)
335 ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
336 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
337 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
341 kex_send_ext_info(struct ssh *ssh)
346 if ((algs = sshkey_alg_list(0, 1, ',')) == NULL)
347 return SSH_ERR_ALLOC_FAIL;
348 if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
349 (r = sshpkt_put_u32(ssh, 1)) != 0 ||
350 (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 ||
351 (r = sshpkt_put_cstring(ssh, algs)) != 0 ||
352 (r = sshpkt_send(ssh)) != 0)
362 kex_send_newkeys(struct ssh *ssh)
366 kex_reset_dispatch(ssh);
367 if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
368 (r = sshpkt_send(ssh)) != 0)
370 debug("SSH2_MSG_NEWKEYS sent");
371 debug("expecting SSH2_MSG_NEWKEYS");
372 ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
373 if (ssh->kex->ext_info_c)
374 if ((r = kex_send_ext_info(ssh)) != 0)
380 kex_input_ext_info(int type, u_int32_t seq, void *ctxt)
382 struct ssh *ssh = ctxt;
383 struct kex *kex = ssh->kex;
385 char *name, *val, *found;
388 debug("SSH2_MSG_EXT_INFO received");
389 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
390 if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
392 for (i = 0; i < ninfo; i++) {
393 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
395 if ((r = sshpkt_get_cstring(ssh, &val, NULL)) != 0) {
399 debug("%s: %s=<%s>", __func__, name, val);
400 if (strcmp(name, "server-sig-algs") == 0) {
401 found = match_list("rsa-sha2-256", val, NULL);
406 found = match_list("rsa-sha2-512", val, NULL);
415 return sshpkt_get_end(ssh);
419 kex_input_newkeys(int type, u_int32_t seq, void *ctxt)
421 struct ssh *ssh = ctxt;
422 struct kex *kex = ssh->kex;
425 debug("SSH2_MSG_NEWKEYS received");
426 ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
427 if ((r = sshpkt_get_end(ssh)) != 0)
429 if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
432 sshbuf_reset(kex->peer);
433 /* sshbuf_reset(kex->my); */
434 kex->flags &= ~KEX_INIT_SENT;
441 kex_send_kexinit(struct ssh *ssh)
444 struct kex *kex = ssh->kex;
448 return SSH_ERR_INTERNAL_ERROR;
449 if (kex->flags & KEX_INIT_SENT)
453 /* generate a random cookie */
454 if (sshbuf_len(kex->my) < KEX_COOKIE_LEN)
455 return SSH_ERR_INVALID_FORMAT;
456 if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL)
457 return SSH_ERR_INTERNAL_ERROR;
458 arc4random_buf(cookie, KEX_COOKIE_LEN);
460 if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
461 (r = sshpkt_putb(ssh, kex->my)) != 0 ||
462 (r = sshpkt_send(ssh)) != 0)
464 debug("SSH2_MSG_KEXINIT sent");
465 kex->flags |= KEX_INIT_SENT;
471 kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
473 struct ssh *ssh = ctxt;
474 struct kex *kex = ssh->kex;
480 debug("SSH2_MSG_KEXINIT received");
482 return SSH_ERR_INVALID_ARGUMENT;
484 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, NULL);
485 ptr = sshpkt_ptr(ssh, &dlen);
486 if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
490 for (i = 0; i < KEX_COOKIE_LEN; i++)
491 if ((r = sshpkt_get_u8(ssh, NULL)) != 0)
493 for (i = 0; i < PROPOSAL_MAX; i++)
494 if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0)
497 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
498 * KEX method has the server move first, but a server might be using
499 * a custom method or one that we otherwise don't support. We should
500 * be prepared to remember first_kex_follows here so we can eat a
502 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
503 * for cases where the server *doesn't* go first. I guess we should
504 * ignore it when it is set for these cases, which is what we do now.
506 if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
507 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
508 (r = sshpkt_get_end(ssh)) != 0)
511 if (!(kex->flags & KEX_INIT_SENT))
512 if ((r = kex_send_kexinit(ssh)) != 0)
514 if ((r = kex_choose_conf(ssh)) != 0)
517 if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
518 return (kex->kex[kex->kex_type])(ssh);
520 return SSH_ERR_INTERNAL_ERROR;
524 kex_new(struct ssh *ssh, char *proposal[PROPOSAL_MAX], struct kex **kexp)
530 if ((kex = calloc(1, sizeof(*kex))) == NULL)
531 return SSH_ERR_ALLOC_FAIL;
532 if ((kex->peer = sshbuf_new()) == NULL ||
533 (kex->my = sshbuf_new()) == NULL) {
534 r = SSH_ERR_ALLOC_FAIL;
537 if ((r = kex_prop2buf(kex->my, proposal)) != 0)
540 kex_reset_dispatch(ssh);
550 kex_free_newkeys(struct newkeys *newkeys)
554 if (newkeys->enc.key) {
555 explicit_bzero(newkeys->enc.key, newkeys->enc.key_len);
556 free(newkeys->enc.key);
557 newkeys->enc.key = NULL;
559 if (newkeys->enc.iv) {
560 explicit_bzero(newkeys->enc.iv, newkeys->enc.iv_len);
561 free(newkeys->enc.iv);
562 newkeys->enc.iv = NULL;
564 free(newkeys->enc.name);
565 explicit_bzero(&newkeys->enc, sizeof(newkeys->enc));
566 free(newkeys->comp.name);
567 explicit_bzero(&newkeys->comp, sizeof(newkeys->comp));
568 mac_clear(&newkeys->mac);
569 if (newkeys->mac.key) {
570 explicit_bzero(newkeys->mac.key, newkeys->mac.key_len);
571 free(newkeys->mac.key);
572 newkeys->mac.key = NULL;
574 free(newkeys->mac.name);
575 explicit_bzero(&newkeys->mac, sizeof(newkeys->mac));
576 explicit_bzero(newkeys, sizeof(*newkeys));
581 kex_free(struct kex *kex)
588 #ifdef OPENSSL_HAS_ECC
589 if (kex->ec_client_key)
590 EC_KEY_free(kex->ec_client_key);
591 #endif /* OPENSSL_HAS_ECC */
592 #endif /* WITH_OPENSSL */
593 for (mode = 0; mode < MODE_MAX; mode++) {
594 kex_free_newkeys(kex->newkeys[mode]);
595 kex->newkeys[mode] = NULL;
597 sshbuf_free(kex->peer);
598 sshbuf_free(kex->my);
599 free(kex->session_id);
600 free(kex->client_version_string);
601 free(kex->server_version_string);
602 free(kex->failed_choice);
603 free(kex->hostkey_alg);
609 kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
613 if ((r = kex_new(ssh, proposal, &ssh->kex)) != 0)
615 if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
624 * Request key re-exchange, returns 0 on success or a ssherr.h error
625 * code otherwise. Must not be called if KEX is incomplete or in-progress.
628 kex_start_rekex(struct ssh *ssh)
630 if (ssh->kex == NULL) {
631 error("%s: no kex", __func__);
632 return SSH_ERR_INTERNAL_ERROR;
634 if (ssh->kex->done == 0) {
635 error("%s: requested twice", __func__);
636 return SSH_ERR_INTERNAL_ERROR;
639 return kex_send_kexinit(ssh);
643 choose_enc(struct sshenc *enc, char *client, char *server)
645 char *name = match_list(client, server, NULL);
648 return SSH_ERR_NO_CIPHER_ALG_MATCH;
649 if ((enc->cipher = cipher_by_name(name)) == NULL)
650 return SSH_ERR_INTERNAL_ERROR;
654 enc->iv_len = cipher_ivlen(enc->cipher);
656 enc->key_len = cipher_keylen(enc->cipher);
657 enc->block_size = cipher_blocksize(enc->cipher);
662 choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
664 char *name = match_list(client, server, NULL);
667 return SSH_ERR_NO_MAC_ALG_MATCH;
668 if (mac_setup(mac, name) < 0)
669 return SSH_ERR_INTERNAL_ERROR;
670 /* truncate the key */
671 if (ssh->compat & SSH_BUG_HMAC)
680 choose_comp(struct sshcomp *comp, char *client, char *server)
682 char *name = match_list(client, server, NULL);
685 return SSH_ERR_NO_COMPRESS_ALG_MATCH;
686 if (strcmp(name, "zlib@openssh.com") == 0) {
687 comp->type = COMP_DELAYED;
688 } else if (strcmp(name, "zlib") == 0) {
689 comp->type = COMP_ZLIB;
690 } else if (strcmp(name, "none") == 0) {
691 comp->type = COMP_NONE;
693 return SSH_ERR_INTERNAL_ERROR;
700 choose_kex(struct kex *k, char *client, char *server)
702 const struct kexalg *kexalg;
704 k->name = match_list(client, server, NULL);
706 debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
708 return SSH_ERR_NO_KEX_ALG_MATCH;
709 if ((kexalg = kex_alg_by_name(k->name)) == NULL)
710 return SSH_ERR_INTERNAL_ERROR;
711 k->kex_type = kexalg->type;
712 k->hash_alg = kexalg->hash_alg;
713 k->ec_nid = kexalg->ec_nid;
718 choose_hostkeyalg(struct kex *k, char *client, char *server)
720 k->hostkey_alg = match_list(client, server, NULL);
722 debug("kex: host key algorithm: %s",
723 k->hostkey_alg ? k->hostkey_alg : "(no match)");
724 if (k->hostkey_alg == NULL)
725 return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
726 k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
727 if (k->hostkey_type == KEY_UNSPEC)
728 return SSH_ERR_INTERNAL_ERROR;
729 k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
734 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
736 static int check[] = {
737 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
742 for (idx = &check[0]; *idx != -1; idx++) {
743 if ((p = strchr(my[*idx], ',')) != NULL)
745 if ((p = strchr(peer[*idx], ',')) != NULL)
747 if (strcmp(my[*idx], peer[*idx]) != 0) {
748 debug2("proposal mismatch: my %s peer %s",
749 my[*idx], peer[*idx]);
753 debug2("proposals match");
758 kex_choose_conf(struct ssh *ssh)
760 struct kex *kex = ssh->kex;
761 struct newkeys *newkeys;
762 char **my = NULL, **peer = NULL;
763 char **cprop, **sprop;
764 int nenc, nmac, ncomp;
765 u_int mode, ctos, need, dh_need, authlen;
766 int r, first_kex_follows;
768 debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
769 if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
771 debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
772 if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
783 /* Check whether client supports ext_info_c */
787 ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
788 kex->ext_info_c = (ext != NULL);
792 /* Algorithm Negotiation */
793 if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
794 sprop[PROPOSAL_KEX_ALGS])) != 0) {
795 kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
796 peer[PROPOSAL_KEX_ALGS] = NULL;
799 if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
800 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
801 kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
802 peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
805 for (mode = 0; mode < MODE_MAX; mode++) {
806 if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
807 r = SSH_ERR_ALLOC_FAIL;
810 kex->newkeys[mode] = newkeys;
811 ctos = (!kex->server && mode == MODE_OUT) ||
812 (kex->server && mode == MODE_IN);
813 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
814 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
815 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
816 if ((r = choose_enc(&newkeys->enc, cprop[nenc],
817 sprop[nenc])) != 0) {
818 kex->failed_choice = peer[nenc];
822 authlen = cipher_authlen(newkeys->enc.cipher);
823 /* ignore mac for authenticated encryption */
825 (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
826 sprop[nmac])) != 0) {
827 kex->failed_choice = peer[nmac];
831 if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
832 sprop[ncomp])) != 0) {
833 kex->failed_choice = peer[ncomp];
837 debug("kex: %s cipher: %s MAC: %s compression: %s",
838 ctos ? "client->server" : "server->client",
840 authlen == 0 ? newkeys->mac.name : "<implicit>",
844 for (mode = 0; mode < MODE_MAX; mode++) {
845 newkeys = kex->newkeys[mode];
846 need = MAXIMUM(need, newkeys->enc.key_len);
847 need = MAXIMUM(need, newkeys->enc.block_size);
848 need = MAXIMUM(need, newkeys->enc.iv_len);
849 need = MAXIMUM(need, newkeys->mac.key_len);
850 dh_need = MAXIMUM(dh_need, cipher_seclen(newkeys->enc.cipher));
851 dh_need = MAXIMUM(dh_need, newkeys->enc.block_size);
852 dh_need = MAXIMUM(dh_need, newkeys->enc.iv_len);
853 dh_need = MAXIMUM(dh_need, newkeys->mac.key_len);
855 /* XXX need runden? */
857 kex->dh_need = dh_need;
859 /* ignore the next message if the proposals do not match */
860 if (first_kex_follows && !proposals_match(my, peer) &&
861 !(ssh->compat & SSH_BUG_FIRSTKEX))
862 ssh->dispatch_skip_packets = 1;
871 derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
872 const struct sshbuf *shared_secret, u_char **keyp)
874 struct kex *kex = ssh->kex;
875 struct ssh_digest_ctx *hashctx = NULL;
882 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
883 return SSH_ERR_INVALID_ARGUMENT;
884 if ((digest = calloc(1, ROUNDUP(need, mdsz))) == NULL) {
885 r = SSH_ERR_ALLOC_FAIL;
889 /* K1 = HASH(K || H || "A" || session_id) */
890 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
891 ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
892 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
893 ssh_digest_update(hashctx, &c, 1) != 0 ||
894 ssh_digest_update(hashctx, kex->session_id,
895 kex->session_id_len) != 0 ||
896 ssh_digest_final(hashctx, digest, mdsz) != 0) {
897 r = SSH_ERR_LIBCRYPTO_ERROR;
900 ssh_digest_free(hashctx);
905 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
906 * Key = K1 || K2 || ... || Kn
908 for (have = mdsz; need > have; have += mdsz) {
909 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
910 ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
911 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
912 ssh_digest_update(hashctx, digest, have) != 0 ||
913 ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
914 r = SSH_ERR_LIBCRYPTO_ERROR;
917 ssh_digest_free(hashctx);
921 fprintf(stderr, "key '%c'== ", c);
922 dump_digest("key", digest, need);
929 ssh_digest_free(hashctx);
935 kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
936 const struct sshbuf *shared_secret)
938 struct kex *kex = ssh->kex;
940 u_int i, j, mode, ctos;
943 for (i = 0; i < NKEYS; i++) {
944 if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
945 shared_secret, &keys[i])) != 0) {
946 for (j = 0; j < i; j++)
951 for (mode = 0; mode < MODE_MAX; mode++) {
952 ctos = (!kex->server && mode == MODE_OUT) ||
953 (kex->server && mode == MODE_IN);
954 kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
955 kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
956 kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
963 kex_derive_keys_bn(struct ssh *ssh, u_char *hash, u_int hashlen,
964 const BIGNUM *secret)
966 struct sshbuf *shared_secret;
969 if ((shared_secret = sshbuf_new()) == NULL)
970 return SSH_ERR_ALLOC_FAIL;
971 if ((r = sshbuf_put_bignum2(shared_secret, secret)) == 0)
972 r = kex_derive_keys(ssh, hash, hashlen, shared_secret);
973 sshbuf_free(shared_secret);
980 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
981 u_int8_t cookie[8], u_int8_t id[16])
983 u_int8_t hbuf[2048], sbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH];
984 struct ssh_digest_ctx *hashctx = NULL;
988 hlen = BN_num_bytes(host_modulus);
989 slen = BN_num_bytes(server_modulus);
990 if (hlen < (512 / 8) || (u_int)hlen > sizeof(hbuf) ||
991 slen < (512 / 8) || (u_int)slen > sizeof(sbuf))
992 return SSH_ERR_KEY_BITS_MISMATCH;
993 if (BN_bn2bin(host_modulus, hbuf) <= 0 ||
994 BN_bn2bin(server_modulus, sbuf) <= 0) {
995 r = SSH_ERR_LIBCRYPTO_ERROR;
998 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL) {
999 r = SSH_ERR_ALLOC_FAIL;
1002 if (ssh_digest_update(hashctx, hbuf, hlen) != 0 ||
1003 ssh_digest_update(hashctx, sbuf, slen) != 0 ||
1004 ssh_digest_update(hashctx, cookie, 8) != 0 ||
1005 ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0) {
1006 r = SSH_ERR_LIBCRYPTO_ERROR;
1009 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5));
1012 ssh_digest_free(hashctx);
1013 explicit_bzero(hbuf, sizeof(hbuf));
1014 explicit_bzero(sbuf, sizeof(sbuf));
1015 explicit_bzero(obuf, sizeof(obuf));
1020 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1022 dump_digest(char *msg, u_char *digest, int len)
1024 fprintf(stderr, "%s\n", msg);
1025 sshbuf_dump_data(digest, len, stderr);