1 /* $OpenBSD: kex.c,v 1.184 2023/12/18 14:45:49 djm 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.
28 #include <sys/types.h>
41 #include <openssl/crypto.h>
42 #include <openssl/dh.h>
60 #include "myproposal.h"
68 static int kex_choose_conf(struct ssh *, uint32_t seq);
69 static int kex_input_newkeys(int, u_int32_t, struct ssh *);
71 static const char * const proposal_names[PROPOSAL_MAX] = {
73 "host key algorithms",
90 static const struct kexalg kexalgs[] = {
92 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
93 { KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
94 { KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
95 { KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
96 { KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
97 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
98 #ifdef HAVE_EVP_SHA256
99 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
100 #endif /* HAVE_EVP_SHA256 */
101 #ifdef OPENSSL_HAS_ECC
102 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
103 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
104 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
106 # ifdef OPENSSL_HAS_NISTP521
107 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
109 # endif /* OPENSSL_HAS_NISTP521 */
110 #endif /* OPENSSL_HAS_ECC */
111 #endif /* WITH_OPENSSL */
112 #if defined(HAVE_EVP_SHA256) || !defined(WITH_OPENSSL)
113 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
114 { KEX_CURVE25519_SHA256_OLD, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
115 #ifdef USE_SNTRUP761X25519
116 { KEX_SNTRUP761X25519_SHA512, KEX_KEM_SNTRUP761X25519_SHA512, 0,
119 #endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */
124 kex_alg_list(char sep)
126 char *ret = NULL, *tmp;
127 size_t nlen, rlen = 0;
128 const struct kexalg *k;
130 for (k = kexalgs; k->name != NULL; k++) {
133 nlen = strlen(k->name);
134 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
139 memcpy(ret + rlen, k->name, nlen + 1);
145 static const struct kexalg *
146 kex_alg_by_name(const char *name)
148 const struct kexalg *k;
150 for (k = kexalgs; k->name != NULL; k++) {
151 if (strcmp(k->name, name) == 0)
157 /* Validate KEX method name list */
159 kex_names_valid(const char *names)
163 if (names == NULL || strcmp(names, "") == 0)
165 if ((s = cp = strdup(names)) == NULL)
167 for ((p = strsep(&cp, ",")); p && *p != '\0';
168 (p = strsep(&cp, ","))) {
169 if (kex_alg_by_name(p) == NULL) {
170 error("Unsupported KEX algorithm \"%.100s\"", p);
175 debug3("kex names ok: [%s]", names);
180 /* returns non-zero if proposal contains any algorithm from algs */
182 has_any_alg(const char *proposal, const char *algs)
186 if ((cp = match_list(proposal, algs, NULL)) == NULL)
193 * Concatenate algorithm names, avoiding duplicates in the process.
194 * Caller must free returned string.
197 kex_names_cat(const char *a, const char *b)
199 char *ret = NULL, *tmp = NULL, *cp, *p;
202 if (a == NULL || *a == '\0')
204 if (b == NULL || *b == '\0')
206 if (strlen(b) > 1024*1024)
208 len = strlen(a) + strlen(b) + 2;
209 if ((tmp = cp = strdup(b)) == NULL ||
210 (ret = calloc(1, len)) == NULL) {
214 strlcpy(ret, a, len);
215 for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
216 if (has_any_alg(ret, p))
217 continue; /* Algorithm already present */
218 if (strlcat(ret, ",", len) >= len ||
219 strlcat(ret, p, len) >= len) {
222 return NULL; /* Shouldn't happen */
230 * Assemble a list of algorithms from a default list and a string from a
231 * configuration file. The user-provided string may begin with '+' to
232 * indicate that it should be appended to the default, '-' that the
233 * specified names should be removed, or '^' that they should be placed
237 kex_assemble_names(char **listp, const char *def, const char *all)
239 char *cp, *tmp, *patterns;
240 char *list = NULL, *ret = NULL, *matching = NULL, *opatterns = NULL;
241 int r = SSH_ERR_INTERNAL_ERROR;
243 if (listp == NULL || def == NULL || all == NULL)
244 return SSH_ERR_INVALID_ARGUMENT;
246 if (*listp == NULL || **listp == '\0') {
247 if ((*listp = strdup(def)) == NULL)
248 return SSH_ERR_ALLOC_FAIL;
255 /* Append names to default list */
256 if ((tmp = kex_names_cat(def, list + 1)) == NULL) {
257 r = SSH_ERR_ALLOC_FAIL;
262 } else if (*list == '-') {
263 /* Remove names from default list */
264 if ((*listp = match_filter_denylist(def, list + 1)) == NULL) {
265 r = SSH_ERR_ALLOC_FAIL;
269 /* filtering has already been done */
271 } else if (*list == '^') {
272 /* Place names at head of default list */
273 if ((tmp = kex_names_cat(list + 1, def)) == NULL) {
274 r = SSH_ERR_ALLOC_FAIL;
280 /* Explicit list, overrides default - just use "list" as is */
284 * The supplied names may be a pattern-list. For the -list case,
285 * the patterns are applied above. For the +list and explicit list
286 * cases we need to do it now.
289 if ((patterns = opatterns = strdup(list)) == NULL) {
290 r = SSH_ERR_ALLOC_FAIL;
293 /* Apply positive (i.e. non-negated) patterns from the list */
294 while ((cp = strsep(&patterns, ",")) != NULL) {
296 /* negated matches are not supported here */
297 r = SSH_ERR_INVALID_ARGUMENT;
301 if ((matching = match_filter_allowlist(all, cp)) == NULL) {
302 r = SSH_ERR_ALLOC_FAIL;
305 if ((tmp = kex_names_cat(ret, matching)) == NULL) {
306 r = SSH_ERR_ALLOC_FAIL;
312 if (ret == NULL || *ret == '\0') {
313 /* An empty name-list is an error */
314 /* XXX better error code? */
315 r = SSH_ERR_INVALID_ARGUMENT;
333 * Fill out a proposal array with dynamically allocated values, which may
334 * be modified as required for compatibility reasons.
335 * Any of the options may be NULL, in which case the default is used.
336 * Array contents must be freed by calling kex_proposal_free_entries.
339 kex_proposal_populate_entries(struct ssh *ssh, char *prop[PROPOSAL_MAX],
340 const char *kexalgos, const char *ciphers, const char *macs,
341 const char *comp, const char *hkalgs)
343 const char *defpropserver[PROPOSAL_MAX] = { KEX_SERVER };
344 const char *defpropclient[PROPOSAL_MAX] = { KEX_CLIENT };
345 const char **defprop = ssh->kex->server ? defpropserver : defpropclient;
350 fatal_f("proposal missing");
352 /* Append EXT_INFO signalling to KexAlgorithms */
353 if (kexalgos == NULL)
354 kexalgos = defprop[PROPOSAL_KEX_ALGS];
355 if ((cp = kex_names_cat(kexalgos, ssh->kex->server ?
356 "ext-info-s,kex-strict-s-v00@openssh.com" :
357 "ext-info-c,kex-strict-c-v00@openssh.com")) == NULL)
358 fatal_f("kex_names_cat");
360 for (i = 0; i < PROPOSAL_MAX; i++) {
362 case PROPOSAL_KEX_ALGS:
363 prop[i] = compat_kex_proposal(ssh, cp);
365 case PROPOSAL_ENC_ALGS_CTOS:
366 case PROPOSAL_ENC_ALGS_STOC:
367 prop[i] = xstrdup(ciphers ? ciphers : defprop[i]);
369 case PROPOSAL_MAC_ALGS_CTOS:
370 case PROPOSAL_MAC_ALGS_STOC:
371 prop[i] = xstrdup(macs ? macs : defprop[i]);
373 case PROPOSAL_COMP_ALGS_CTOS:
374 case PROPOSAL_COMP_ALGS_STOC:
375 prop[i] = xstrdup(comp ? comp : defprop[i]);
377 case PROPOSAL_SERVER_HOST_KEY_ALGS:
378 prop[i] = xstrdup(hkalgs ? hkalgs : defprop[i]);
381 prop[i] = xstrdup(defprop[i]);
388 kex_proposal_free_entries(char *prop[PROPOSAL_MAX])
392 for (i = 0; i < PROPOSAL_MAX; i++)
396 /* put algorithm proposal into buffer */
398 kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
406 * add a dummy cookie, the cookie will be overwritten by
407 * kex_send_kexinit(), each time a kexinit is set
409 for (i = 0; i < KEX_COOKIE_LEN; i++) {
410 if ((r = sshbuf_put_u8(b, 0)) != 0)
413 for (i = 0; i < PROPOSAL_MAX; i++) {
414 if ((r = sshbuf_put_cstring(b, proposal[i])) != 0)
417 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* first_kex_packet_follows */
418 (r = sshbuf_put_u32(b, 0)) != 0) /* uint32 reserved */
423 /* parse buffer and return algorithm proposal */
425 kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
427 struct sshbuf *b = NULL;
430 char **proposal = NULL;
434 if ((proposal = calloc(PROPOSAL_MAX, sizeof(char *))) == NULL)
435 return SSH_ERR_ALLOC_FAIL;
436 if ((b = sshbuf_fromb(raw)) == NULL) {
437 r = SSH_ERR_ALLOC_FAIL;
440 if ((r = sshbuf_consume(b, KEX_COOKIE_LEN)) != 0) { /* skip cookie */
441 error_fr(r, "consume cookie");
444 /* extract kex init proposal strings */
445 for (i = 0; i < PROPOSAL_MAX; i++) {
446 if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0) {
447 error_fr(r, "parse proposal %u", i);
450 debug2("%s: %s", proposal_names[i], proposal[i]);
452 /* first kex follows / reserved */
453 if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
454 (r = sshbuf_get_u32(b, &i)) != 0) { /* reserved */
455 error_fr(r, "parse");
458 if (first_kex_follows != NULL)
459 *first_kex_follows = v;
460 debug2("first_kex_follows %d ", v);
461 debug2("reserved %u ", i);
465 if (r != 0 && proposal != NULL)
466 kex_prop_free(proposal);
472 kex_prop_free(char **proposal)
476 if (proposal == NULL)
478 for (i = 0; i < PROPOSAL_MAX; i++)
484 kex_protocol_error(int type, u_int32_t seq, struct ssh *ssh)
488 /* If in strict mode, any unexpected message is an error */
489 if ((ssh->kex->flags & KEX_INITIAL) && ssh->kex->kex_strict) {
490 ssh_packet_disconnect(ssh, "strict KEX violation: "
491 "unexpected packet type %u (seqnr %u)", type, seq);
493 error_f("type %u seq %u", type, seq);
494 if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
495 (r = sshpkt_put_u32(ssh, seq)) != 0 ||
496 (r = sshpkt_send(ssh)) != 0)
502 kex_reset_dispatch(struct ssh *ssh)
504 ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
505 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
509 kex_set_server_sig_algs(struct ssh *ssh, const char *allowed_algs)
511 char *alg, *oalgs, *algs, *sigalgs;
515 * NB. allowed algorithms may contain certificate algorithms that
516 * map to a specific plain signature type, e.g.
517 * rsa-sha2-512-cert-v01@openssh.com => rsa-sha2-512
518 * We need to be careful here to match these, retain the mapping
519 * and only add each signature algorithm once.
521 if ((sigalgs = sshkey_alg_list(0, 1, 1, ',')) == NULL)
522 fatal_f("sshkey_alg_list failed");
523 oalgs = algs = xstrdup(allowed_algs);
524 free(ssh->kex->server_sig_algs);
525 ssh->kex->server_sig_algs = NULL;
526 for ((alg = strsep(&algs, ",")); alg != NULL && *alg != '\0';
527 (alg = strsep(&algs, ","))) {
528 if ((sigalg = sshkey_sigalg_by_name(alg)) == NULL)
530 if (!has_any_alg(sigalg, sigalgs))
532 /* Don't add an algorithm twice. */
533 if (ssh->kex->server_sig_algs != NULL &&
534 has_any_alg(sigalg, ssh->kex->server_sig_algs))
536 xextendf(&ssh->kex->server_sig_algs, ",", "%s", sigalg);
540 if (ssh->kex->server_sig_algs == NULL)
541 ssh->kex->server_sig_algs = xstrdup("");
545 kex_compose_ext_info_server(struct ssh *ssh, struct sshbuf *m)
549 if (ssh->kex->server_sig_algs == NULL &&
550 (ssh->kex->server_sig_algs = sshkey_alg_list(0, 1, 1, ',')) == NULL)
551 return SSH_ERR_ALLOC_FAIL;
552 if ((r = sshbuf_put_u32(m, 3)) != 0 ||
553 (r = sshbuf_put_cstring(m, "server-sig-algs")) != 0 ||
554 (r = sshbuf_put_cstring(m, ssh->kex->server_sig_algs)) != 0 ||
555 (r = sshbuf_put_cstring(m,
556 "publickey-hostbound@openssh.com")) != 0 ||
557 (r = sshbuf_put_cstring(m, "0")) != 0 ||
558 (r = sshbuf_put_cstring(m, "ping@openssh.com")) != 0 ||
559 (r = sshbuf_put_cstring(m, "0")) != 0) {
560 error_fr(r, "compose");
567 kex_compose_ext_info_client(struct ssh *ssh, struct sshbuf *m)
571 if ((r = sshbuf_put_u32(m, 1)) != 0 ||
572 (r = sshbuf_put_cstring(m, "ext-info-in-auth@openssh.com")) != 0 ||
573 (r = sshbuf_put_cstring(m, "0")) != 0) {
574 error_fr(r, "compose");
584 kex_maybe_send_ext_info(struct ssh *ssh)
587 struct sshbuf *m = NULL;
589 if ((ssh->kex->flags & KEX_INITIAL) == 0)
591 if (!ssh->kex->ext_info_c && !ssh->kex->ext_info_s)
594 /* Compose EXT_INFO packet. */
595 if ((m = sshbuf_new()) == NULL)
596 fatal_f("sshbuf_new failed");
597 if (ssh->kex->ext_info_c &&
598 (r = kex_compose_ext_info_server(ssh, m)) != 0)
600 if (ssh->kex->ext_info_s &&
601 (r = kex_compose_ext_info_client(ssh, m)) != 0)
604 /* Send the actual KEX_INFO packet */
605 debug("Sending SSH2_MSG_EXT_INFO");
606 if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
607 (r = sshpkt_putb(ssh, m)) != 0 ||
608 (r = sshpkt_send(ssh)) != 0) {
609 error_f("send EXT_INFO");
621 kex_server_update_ext_info(struct ssh *ssh)
625 if ((ssh->kex->flags & KEX_HAS_EXT_INFO_IN_AUTH) == 0)
628 debug_f("Sending SSH2_MSG_EXT_INFO");
629 if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
630 (r = sshpkt_put_u32(ssh, 1)) != 0 ||
631 (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 ||
632 (r = sshpkt_put_cstring(ssh, ssh->kex->server_sig_algs)) != 0 ||
633 (r = sshpkt_send(ssh)) != 0) {
634 error_f("send EXT_INFO");
641 kex_send_newkeys(struct ssh *ssh)
645 kex_reset_dispatch(ssh);
646 if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
647 (r = sshpkt_send(ssh)) != 0)
649 debug("SSH2_MSG_NEWKEYS sent");
650 ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
651 if ((r = kex_maybe_send_ext_info(ssh)) != 0)
653 debug("expecting SSH2_MSG_NEWKEYS");
657 /* Check whether an ext_info value contains the expected version string */
659 kex_ext_info_check_ver(struct kex *kex, const char *name,
660 const u_char *val, size_t len, const char *want_ver, u_int flag)
662 if (memchr(val, '\0', len) != NULL) {
663 error("SSH2_MSG_EXT_INFO: %s value contains nul byte", name);
664 return SSH_ERR_INVALID_FORMAT;
666 debug_f("%s=<%s>", name, val);
667 if (strcmp(val, want_ver) == 0)
670 debug_f("unsupported version of %s extension", name);
675 kex_ext_info_client_parse(struct ssh *ssh, const char *name,
676 const u_char *value, size_t vlen)
680 /* NB. some messages are only accepted in the initial EXT_INFO */
681 if (strcmp(name, "server-sig-algs") == 0) {
682 /* Ensure no \0 lurking in value */
683 if (memchr(value, '\0', vlen) != NULL) {
684 error_f("nul byte in %s", name);
685 return SSH_ERR_INVALID_FORMAT;
687 debug_f("%s=<%s>", name, value);
688 free(ssh->kex->server_sig_algs);
689 ssh->kex->server_sig_algs = xstrdup((const char *)value);
690 } else if (ssh->kex->ext_info_received == 1 &&
691 strcmp(name, "publickey-hostbound@openssh.com") == 0) {
692 if ((r = kex_ext_info_check_ver(ssh->kex, name, value, vlen,
693 "0", KEX_HAS_PUBKEY_HOSTBOUND)) != 0) {
696 } else if (ssh->kex->ext_info_received == 1 &&
697 strcmp(name, "ping@openssh.com") == 0) {
698 if ((r = kex_ext_info_check_ver(ssh->kex, name, value, vlen,
699 "0", KEX_HAS_PING)) != 0) {
703 debug_f("%s (unrecognised)", name);
709 kex_ext_info_server_parse(struct ssh *ssh, const char *name,
710 const u_char *value, size_t vlen)
714 if (strcmp(name, "ext-info-in-auth@openssh.com") == 0) {
715 if ((r = kex_ext_info_check_ver(ssh->kex, name, value, vlen,
716 "0", KEX_HAS_EXT_INFO_IN_AUTH)) != 0) {
720 debug_f("%s (unrecognised)", name);
725 kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
727 struct kex *kex = ssh->kex;
728 const int max_ext_info = kex->server ? 1 : 2;
735 debug("SSH2_MSG_EXT_INFO received");
736 if (++kex->ext_info_received > max_ext_info) {
737 error("too many SSH2_MSG_EXT_INFO messages sent by peer");
738 return dispatch_protocol_error(type, seq, ssh);
740 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
741 if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
744 error("SSH2_MSG_EXT_INFO with too many entries, expected "
745 "<=1024, received %u", ninfo);
746 return dispatch_protocol_error(type, seq, ssh);
748 for (i = 0; i < ninfo; i++) {
749 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
751 if ((r = sshpkt_get_string(ssh, &val, &vlen)) != 0) {
755 debug3_f("extension %s", name);
757 if ((r = kex_ext_info_server_parse(ssh, name,
761 if ((r = kex_ext_info_client_parse(ssh, name,
768 return sshpkt_get_end(ssh);
772 kex_input_newkeys(int type, u_int32_t seq, struct ssh *ssh)
774 struct kex *kex = ssh->kex;
777 debug("SSH2_MSG_NEWKEYS received");
778 if (kex->ext_info_c && (kex->flags & KEX_INITIAL) != 0)
779 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info);
780 ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
781 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
782 if ((r = sshpkt_get_end(ssh)) != 0)
784 if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
787 kex->flags &= ~KEX_INITIAL;
788 sshbuf_reset(kex->peer);
789 /* sshbuf_reset(kex->my); */
790 kex->flags &= ~KEX_INIT_SENT;
797 kex_send_kexinit(struct ssh *ssh)
800 struct kex *kex = ssh->kex;
805 return SSH_ERR_INTERNAL_ERROR;
807 if (kex->flags & KEX_INIT_SENT)
811 /* generate a random cookie */
812 if (sshbuf_len(kex->my) < KEX_COOKIE_LEN) {
813 error_f("bad kex length: %zu < %d",
814 sshbuf_len(kex->my), KEX_COOKIE_LEN);
815 return SSH_ERR_INVALID_FORMAT;
817 if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL) {
818 error_f("buffer error");
819 return SSH_ERR_INTERNAL_ERROR;
821 arc4random_buf(cookie, KEX_COOKIE_LEN);
823 if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
824 (r = sshpkt_putb(ssh, kex->my)) != 0 ||
825 (r = sshpkt_send(ssh)) != 0) {
826 error_fr(r, "compose reply");
829 debug("SSH2_MSG_KEXINIT sent");
830 kex->flags |= KEX_INIT_SENT;
835 kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
837 struct kex *kex = ssh->kex;
843 debug("SSH2_MSG_KEXINIT received");
846 return SSH_ERR_INTERNAL_ERROR;
848 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_protocol_error);
849 ptr = sshpkt_ptr(ssh, &dlen);
850 if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
854 for (i = 0; i < KEX_COOKIE_LEN; i++) {
855 if ((r = sshpkt_get_u8(ssh, NULL)) != 0) {
856 error_fr(r, "discard cookie");
860 for (i = 0; i < PROPOSAL_MAX; i++) {
861 if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
862 error_fr(r, "discard proposal");
867 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
868 * KEX method has the server move first, but a server might be using
869 * a custom method or one that we otherwise don't support. We should
870 * be prepared to remember first_kex_follows here so we can eat a
872 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
873 * for cases where the server *doesn't* go first. I guess we should
874 * ignore it when it is set for these cases, which is what we do now.
876 if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
877 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
878 (r = sshpkt_get_end(ssh)) != 0)
881 if (!(kex->flags & KEX_INIT_SENT))
882 if ((r = kex_send_kexinit(ssh)) != 0)
884 if ((r = kex_choose_conf(ssh, seq)) != 0)
887 if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
888 return (kex->kex[kex->kex_type])(ssh);
890 error_f("unknown kex type %u", kex->kex_type);
891 return SSH_ERR_INTERNAL_ERROR;
899 if ((kex = calloc(1, sizeof(*kex))) == NULL ||
900 (kex->peer = sshbuf_new()) == NULL ||
901 (kex->my = sshbuf_new()) == NULL ||
902 (kex->client_version = sshbuf_new()) == NULL ||
903 (kex->server_version = sshbuf_new()) == NULL ||
904 (kex->session_id = sshbuf_new()) == NULL) {
912 kex_free_newkeys(struct newkeys *newkeys)
916 if (newkeys->enc.key) {
917 explicit_bzero(newkeys->enc.key, newkeys->enc.key_len);
918 free(newkeys->enc.key);
919 newkeys->enc.key = NULL;
921 if (newkeys->enc.iv) {
922 explicit_bzero(newkeys->enc.iv, newkeys->enc.iv_len);
923 free(newkeys->enc.iv);
924 newkeys->enc.iv = NULL;
926 free(newkeys->enc.name);
927 explicit_bzero(&newkeys->enc, sizeof(newkeys->enc));
928 free(newkeys->comp.name);
929 explicit_bzero(&newkeys->comp, sizeof(newkeys->comp));
930 mac_clear(&newkeys->mac);
931 if (newkeys->mac.key) {
932 explicit_bzero(newkeys->mac.key, newkeys->mac.key_len);
933 free(newkeys->mac.key);
934 newkeys->mac.key = NULL;
936 free(newkeys->mac.name);
937 explicit_bzero(&newkeys->mac, sizeof(newkeys->mac));
938 freezero(newkeys, sizeof(*newkeys));
942 kex_free(struct kex *kex)
951 #ifdef OPENSSL_HAS_ECC
952 EC_KEY_free(kex->ec_client_key);
953 #endif /* OPENSSL_HAS_ECC */
954 #endif /* WITH_OPENSSL */
955 for (mode = 0; mode < MODE_MAX; mode++) {
956 kex_free_newkeys(kex->newkeys[mode]);
957 kex->newkeys[mode] = NULL;
959 sshbuf_free(kex->peer);
960 sshbuf_free(kex->my);
961 sshbuf_free(kex->client_version);
962 sshbuf_free(kex->server_version);
963 sshbuf_free(kex->client_pub);
964 sshbuf_free(kex->session_id);
965 sshbuf_free(kex->initial_sig);
966 sshkey_free(kex->initial_hostkey);
967 free(kex->failed_choice);
968 free(kex->hostkey_alg);
974 kex_ready(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
978 if ((r = kex_prop2buf(ssh->kex->my, proposal)) != 0)
980 ssh->kex->flags = KEX_INITIAL;
981 kex_reset_dispatch(ssh);
982 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
987 kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
991 if ((r = kex_ready(ssh, proposal)) != 0)
993 if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
1002 * Request key re-exchange, returns 0 on success or a ssherr.h error
1003 * code otherwise. Must not be called if KEX is incomplete or in-progress.
1006 kex_start_rekex(struct ssh *ssh)
1008 if (ssh->kex == NULL) {
1010 return SSH_ERR_INTERNAL_ERROR;
1012 if (ssh->kex->done == 0) {
1013 error_f("requested twice");
1014 return SSH_ERR_INTERNAL_ERROR;
1017 return kex_send_kexinit(ssh);
1021 choose_enc(struct sshenc *enc, char *client, char *server)
1023 char *name = match_list(client, server, NULL);
1026 return SSH_ERR_NO_CIPHER_ALG_MATCH;
1027 if ((enc->cipher = cipher_by_name(name)) == NULL) {
1028 error_f("unsupported cipher %s", name);
1030 return SSH_ERR_INTERNAL_ERROR;
1035 enc->iv_len = cipher_ivlen(enc->cipher);
1037 enc->key_len = cipher_keylen(enc->cipher);
1038 enc->block_size = cipher_blocksize(enc->cipher);
1043 choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
1045 char *name = match_list(client, server, NULL);
1048 return SSH_ERR_NO_MAC_ALG_MATCH;
1049 if (mac_setup(mac, name) < 0) {
1050 error_f("unsupported MAC %s", name);
1052 return SSH_ERR_INTERNAL_ERROR;
1061 choose_comp(struct sshcomp *comp, char *client, char *server)
1063 char *name = match_list(client, server, NULL);
1066 return SSH_ERR_NO_COMPRESS_ALG_MATCH;
1068 if (strcmp(name, "zlib@openssh.com") == 0) {
1069 comp->type = COMP_DELAYED;
1070 } else if (strcmp(name, "zlib") == 0) {
1071 comp->type = COMP_ZLIB;
1073 #endif /* WITH_ZLIB */
1074 if (strcmp(name, "none") == 0) {
1075 comp->type = COMP_NONE;
1077 error_f("unsupported compression scheme %s", name);
1079 return SSH_ERR_INTERNAL_ERROR;
1086 choose_kex(struct kex *k, char *client, char *server)
1088 const struct kexalg *kexalg;
1090 k->name = match_list(client, server, NULL);
1092 debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
1093 if (k->name == NULL)
1094 return SSH_ERR_NO_KEX_ALG_MATCH;
1095 if ((kexalg = kex_alg_by_name(k->name)) == NULL) {
1096 error_f("unsupported KEX method %s", k->name);
1097 return SSH_ERR_INTERNAL_ERROR;
1099 k->kex_type = kexalg->type;
1100 k->hash_alg = kexalg->hash_alg;
1101 k->ec_nid = kexalg->ec_nid;
1106 choose_hostkeyalg(struct kex *k, char *client, char *server)
1108 free(k->hostkey_alg);
1109 k->hostkey_alg = match_list(client, server, NULL);
1111 debug("kex: host key algorithm: %s",
1112 k->hostkey_alg ? k->hostkey_alg : "(no match)");
1113 if (k->hostkey_alg == NULL)
1114 return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
1115 k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
1116 if (k->hostkey_type == KEY_UNSPEC) {
1117 error_f("unsupported hostkey algorithm %s", k->hostkey_alg);
1118 return SSH_ERR_INTERNAL_ERROR;
1120 k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
1125 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
1127 static int check[] = {
1128 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
1133 for (idx = &check[0]; *idx != -1; idx++) {
1134 if ((p = strchr(my[*idx], ',')) != NULL)
1136 if ((p = strchr(peer[*idx], ',')) != NULL)
1138 if (strcmp(my[*idx], peer[*idx]) != 0) {
1139 debug2("proposal mismatch: my %s peer %s",
1140 my[*idx], peer[*idx]);
1144 debug2("proposals match");
1149 kexalgs_contains(char **peer, const char *ext)
1151 return has_any_alg(peer[PROPOSAL_KEX_ALGS], ext);
1155 kex_choose_conf(struct ssh *ssh, uint32_t seq)
1157 struct kex *kex = ssh->kex;
1158 struct newkeys *newkeys;
1159 char **my = NULL, **peer = NULL;
1160 char **cprop, **sprop;
1161 int nenc, nmac, ncomp;
1162 u_int mode, ctos, need, dh_need, authlen;
1163 int r, first_kex_follows;
1165 debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
1166 if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
1168 debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
1169 if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
1180 /* Check whether peer supports ext_info/kex_strict */
1181 if ((kex->flags & KEX_INITIAL) != 0) {
1183 kex->ext_info_c = kexalgs_contains(peer, "ext-info-c");
1184 kex->kex_strict = kexalgs_contains(peer,
1185 "kex-strict-c-v00@openssh.com");
1187 kex->ext_info_s = kexalgs_contains(peer, "ext-info-s");
1188 kex->kex_strict = kexalgs_contains(peer,
1189 "kex-strict-s-v00@openssh.com");
1191 if (kex->kex_strict) {
1192 debug3_f("will use strict KEX ordering");
1194 ssh_packet_disconnect(ssh,
1195 "strict KEX violation: "
1196 "KEXINIT was not the first packet");
1200 /* Check whether client supports rsa-sha2 algorithms */
1201 if (kex->server && (kex->flags & KEX_INITIAL)) {
1202 if (has_any_alg(peer[PROPOSAL_SERVER_HOST_KEY_ALGS],
1203 "rsa-sha2-256,rsa-sha2-256-cert-v01@openssh.com"))
1204 kex->flags |= KEX_RSA_SHA2_256_SUPPORTED;
1205 if (has_any_alg(peer[PROPOSAL_SERVER_HOST_KEY_ALGS],
1206 "rsa-sha2-512,rsa-sha2-512-cert-v01@openssh.com"))
1207 kex->flags |= KEX_RSA_SHA2_512_SUPPORTED;
1210 /* Algorithm Negotiation */
1211 if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
1212 sprop[PROPOSAL_KEX_ALGS])) != 0) {
1213 kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
1214 peer[PROPOSAL_KEX_ALGS] = NULL;
1217 if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
1218 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
1219 kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
1220 peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
1223 for (mode = 0; mode < MODE_MAX; mode++) {
1224 if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
1225 r = SSH_ERR_ALLOC_FAIL;
1228 kex->newkeys[mode] = newkeys;
1229 ctos = (!kex->server && mode == MODE_OUT) ||
1230 (kex->server && mode == MODE_IN);
1231 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
1232 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
1233 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1234 if ((r = choose_enc(&newkeys->enc, cprop[nenc],
1235 sprop[nenc])) != 0) {
1236 kex->failed_choice = peer[nenc];
1240 authlen = cipher_authlen(newkeys->enc.cipher);
1241 /* ignore mac for authenticated encryption */
1243 (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
1244 sprop[nmac])) != 0) {
1245 kex->failed_choice = peer[nmac];
1249 if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
1250 sprop[ncomp])) != 0) {
1251 kex->failed_choice = peer[ncomp];
1255 debug("kex: %s cipher: %s MAC: %s compression: %s",
1256 ctos ? "client->server" : "server->client",
1258 authlen == 0 ? newkeys->mac.name : "<implicit>",
1259 newkeys->comp.name);
1262 for (mode = 0; mode < MODE_MAX; mode++) {
1263 newkeys = kex->newkeys[mode];
1264 need = MAXIMUM(need, newkeys->enc.key_len);
1265 need = MAXIMUM(need, newkeys->enc.block_size);
1266 need = MAXIMUM(need, newkeys->enc.iv_len);
1267 need = MAXIMUM(need, newkeys->mac.key_len);
1268 dh_need = MAXIMUM(dh_need, cipher_seclen(newkeys->enc.cipher));
1269 dh_need = MAXIMUM(dh_need, newkeys->enc.block_size);
1270 dh_need = MAXIMUM(dh_need, newkeys->enc.iv_len);
1271 dh_need = MAXIMUM(dh_need, newkeys->mac.key_len);
1273 /* XXX need runden? */
1274 kex->we_need = need;
1275 kex->dh_need = dh_need;
1277 /* ignore the next message if the proposals do not match */
1278 if (first_kex_follows && !proposals_match(my, peer))
1279 ssh->dispatch_skip_packets = 1;
1283 kex_prop_free(peer);
1288 derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
1289 const struct sshbuf *shared_secret, u_char **keyp)
1291 struct kex *kex = ssh->kex;
1292 struct ssh_digest_ctx *hashctx = NULL;
1299 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
1300 return SSH_ERR_INVALID_ARGUMENT;
1301 if ((digest = calloc(1, ROUNDUP(need, mdsz))) == NULL) {
1302 r = SSH_ERR_ALLOC_FAIL;
1306 /* K1 = HASH(K || H || "A" || session_id) */
1307 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1308 ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1309 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1310 ssh_digest_update(hashctx, &c, 1) != 0 ||
1311 ssh_digest_update_buffer(hashctx, kex->session_id) != 0 ||
1312 ssh_digest_final(hashctx, digest, mdsz) != 0) {
1313 r = SSH_ERR_LIBCRYPTO_ERROR;
1314 error_f("KEX hash failed");
1317 ssh_digest_free(hashctx);
1322 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
1323 * Key = K1 || K2 || ... || Kn
1325 for (have = mdsz; need > have; have += mdsz) {
1326 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1327 ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1328 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1329 ssh_digest_update(hashctx, digest, have) != 0 ||
1330 ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
1331 error_f("KDF failed");
1332 r = SSH_ERR_LIBCRYPTO_ERROR;
1335 ssh_digest_free(hashctx);
1339 fprintf(stderr, "key '%c'== ", c);
1340 dump_digest("key", digest, need);
1347 ssh_digest_free(hashctx);
1353 kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
1354 const struct sshbuf *shared_secret)
1356 struct kex *kex = ssh->kex;
1357 u_char *keys[NKEYS];
1358 u_int i, j, mode, ctos;
1361 /* save initial hash as session id */
1362 if ((kex->flags & KEX_INITIAL) != 0) {
1363 if (sshbuf_len(kex->session_id) != 0) {
1364 error_f("already have session ID at kex");
1365 return SSH_ERR_INTERNAL_ERROR;
1367 if ((r = sshbuf_put(kex->session_id, hash, hashlen)) != 0)
1369 } else if (sshbuf_len(kex->session_id) == 0) {
1370 error_f("no session ID in rekex");
1371 return SSH_ERR_INTERNAL_ERROR;
1373 for (i = 0; i < NKEYS; i++) {
1374 if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
1375 shared_secret, &keys[i])) != 0) {
1376 for (j = 0; j < i; j++)
1381 for (mode = 0; mode < MODE_MAX; mode++) {
1382 ctos = (!kex->server && mode == MODE_OUT) ||
1383 (kex->server && mode == MODE_IN);
1384 kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
1385 kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
1386 kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
1392 kex_load_hostkey(struct ssh *ssh, struct sshkey **prvp, struct sshkey **pubp)
1394 struct kex *kex = ssh->kex;
1398 if (kex->load_host_public_key == NULL ||
1399 kex->load_host_private_key == NULL) {
1400 error_f("missing hostkey loader");
1401 return SSH_ERR_INVALID_ARGUMENT;
1403 *pubp = kex->load_host_public_key(kex->hostkey_type,
1404 kex->hostkey_nid, ssh);
1405 *prvp = kex->load_host_private_key(kex->hostkey_type,
1406 kex->hostkey_nid, ssh);
1408 return SSH_ERR_NO_HOSTKEY_LOADED;
1413 kex_verify_host_key(struct ssh *ssh, struct sshkey *server_host_key)
1415 struct kex *kex = ssh->kex;
1417 if (kex->verify_host_key == NULL) {
1418 error_f("missing hostkey verifier");
1419 return SSH_ERR_INVALID_ARGUMENT;
1421 if (server_host_key->type != kex->hostkey_type ||
1422 (kex->hostkey_type == KEY_ECDSA &&
1423 server_host_key->ecdsa_nid != kex->hostkey_nid))
1424 return SSH_ERR_KEY_TYPE_MISMATCH;
1425 if (kex->verify_host_key(server_host_key, ssh) == -1)
1426 return SSH_ERR_SIGNATURE_INVALID;
1430 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1432 dump_digest(const char *msg, const u_char *digest, int len)
1434 fprintf(stderr, "%s\n", msg);
1435 sshbuf_dump_data(digest, len, stderr);
1440 * Send a plaintext error message to the peer, suffixed by \r\n.
1441 * Only used during banner exchange, and there only for the server.
1444 send_error(struct ssh *ssh, char *msg)
1446 char *crnl = "\r\n";
1448 if (!ssh->kex->server)
1451 if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1452 msg, strlen(msg)) != strlen(msg) ||
1453 atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1454 crnl, strlen(crnl)) != strlen(crnl))
1455 error_f("write: %.100s", strerror(errno));
1459 * Sends our identification string and waits for the peer's. Will block for
1460 * up to timeout_ms (or indefinitely if timeout_ms <= 0).
1461 * Returns on 0 success or a ssherr.h code on failure.
1464 kex_exchange_identification(struct ssh *ssh, int timeout_ms,
1465 const char *version_addendum)
1467 int remote_major, remote_minor, mismatch, oerrno = 0;
1471 struct sshbuf *our_version = ssh->kex->server ?
1472 ssh->kex->server_version : ssh->kex->client_version;
1473 struct sshbuf *peer_version = ssh->kex->server ?
1474 ssh->kex->client_version : ssh->kex->server_version;
1475 char *our_version_string = NULL, *peer_version_string = NULL;
1476 char *cp, *remote_version = NULL;
1478 /* Prepare and send our banner */
1479 sshbuf_reset(our_version);
1480 if (version_addendum != NULL && *version_addendum == '\0')
1481 version_addendum = NULL;
1482 if ((r = sshbuf_putf(our_version, "SSH-%d.%d-%s%s%s\r\n",
1483 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
1484 version_addendum == NULL ? "" : " ",
1485 version_addendum == NULL ? "" : version_addendum)) != 0) {
1487 error_fr(r, "sshbuf_putf");
1491 if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1492 sshbuf_mutable_ptr(our_version),
1493 sshbuf_len(our_version)) != sshbuf_len(our_version)) {
1495 debug_f("write: %.100s", strerror(errno));
1496 r = SSH_ERR_SYSTEM_ERROR;
1499 if ((r = sshbuf_consume_end(our_version, 2)) != 0) { /* trim \r\n */
1501 error_fr(r, "sshbuf_consume_end");
1504 our_version_string = sshbuf_dup_string(our_version);
1505 if (our_version_string == NULL) {
1506 error_f("sshbuf_dup_string failed");
1507 r = SSH_ERR_ALLOC_FAIL;
1510 debug("Local version string %.100s", our_version_string);
1512 /* Read other side's version identification. */
1513 for (n = 0; ; n++) {
1514 if (n >= SSH_MAX_PRE_BANNER_LINES) {
1515 send_error(ssh, "No SSH identification string "
1517 error_f("No SSH version received in first %u lines "
1518 "from server", SSH_MAX_PRE_BANNER_LINES);
1519 r = SSH_ERR_INVALID_FORMAT;
1522 sshbuf_reset(peer_version);
1525 if (timeout_ms > 0) {
1526 r = waitrfd(ssh_packet_get_connection_in(ssh),
1528 if (r == -1 && errno == ETIMEDOUT) {
1529 send_error(ssh, "Timed out waiting "
1530 "for SSH identification string.");
1531 error("Connection timed out during "
1533 r = SSH_ERR_CONN_TIMEOUT;
1535 } else if (r == -1) {
1537 error_f("%s", strerror(errno));
1538 r = SSH_ERR_SYSTEM_ERROR;
1543 len = atomicio(read, ssh_packet_get_connection_in(ssh),
1545 if (len != 1 && errno == EPIPE) {
1546 verbose_f("Connection closed by remote host");
1547 r = SSH_ERR_CONN_CLOSED;
1549 } else if (len != 1) {
1551 error_f("read: %.100s", strerror(errno));
1552 r = SSH_ERR_SYSTEM_ERROR;
1561 if (c == '\0' || expect_nl) {
1562 verbose_f("banner line contains invalid "
1566 if ((r = sshbuf_put_u8(peer_version, c)) != 0) {
1568 error_fr(r, "sshbuf_put");
1571 if (sshbuf_len(peer_version) > SSH_MAX_BANNER_LEN) {
1572 verbose_f("banner line too long");
1576 /* Is this an actual protocol banner? */
1577 if (sshbuf_len(peer_version) > 4 &&
1578 memcmp(sshbuf_ptr(peer_version), "SSH-", 4) == 0)
1580 /* If not, then just log the line and continue */
1581 if ((cp = sshbuf_dup_string(peer_version)) == NULL) {
1582 error_f("sshbuf_dup_string failed");
1583 r = SSH_ERR_ALLOC_FAIL;
1586 /* Do not accept lines before the SSH ident from a client */
1587 if (ssh->kex->server) {
1588 verbose_f("client sent invalid protocol identifier "
1593 debug_f("banner line %zu: %s", n, cp);
1596 peer_version_string = sshbuf_dup_string(peer_version);
1597 if (peer_version_string == NULL)
1598 fatal_f("sshbuf_dup_string failed");
1599 /* XXX must be same size for sscanf */
1600 if ((remote_version = calloc(1, sshbuf_len(peer_version))) == NULL) {
1601 error_f("calloc failed");
1602 r = SSH_ERR_ALLOC_FAIL;
1607 * Check that the versions match. In future this might accept
1608 * several versions and set appropriate flags to handle them.
1610 if (sscanf(peer_version_string, "SSH-%d.%d-%[^\n]\n",
1611 &remote_major, &remote_minor, remote_version) != 3) {
1612 error("Bad remote protocol version identification: '%.100s'",
1613 peer_version_string);
1615 send_error(ssh, "Invalid SSH identification string.");
1616 r = SSH_ERR_INVALID_FORMAT;
1619 debug("Remote protocol version %d.%d, remote software version %.100s",
1620 remote_major, remote_minor, remote_version);
1621 compat_banner(ssh, remote_version);
1624 switch (remote_major) {
1628 if (remote_minor != 99)
1636 error("Protocol major versions differ: %d vs. %d",
1637 PROTOCOL_MAJOR_2, remote_major);
1638 send_error(ssh, "Protocol major versions differ.");
1639 r = SSH_ERR_NO_PROTOCOL_VERSION;
1643 if (ssh->kex->server && (ssh->compat & SSH_BUG_PROBE) != 0) {
1644 logit("probed from %s port %d with %s. Don't panic.",
1645 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1646 peer_version_string);
1647 r = SSH_ERR_CONN_CLOSED; /* XXX */
1650 if (ssh->kex->server && (ssh->compat & SSH_BUG_SCANNER) != 0) {
1651 logit("scanned from %s port %d with %s. Don't panic.",
1652 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1653 peer_version_string);
1654 r = SSH_ERR_CONN_CLOSED; /* XXX */
1660 free(our_version_string);
1661 free(peer_version_string);
1662 free(remote_version);
1663 if (r == SSH_ERR_SYSTEM_ERROR)