Annotation of src/usr.bin/ssh/kex.c, Revision 1.152
1.152 ! djm 1: /* $OpenBSD: kex.c,v 1.151 2019/09/05 09:25:13 djm Exp $ */
1.1 markus 2: /*
1.36 markus 3: * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
1.1 markus 4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
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.
13: *
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.
24: */
25:
1.18 markus 26:
1.143 djm 27: #include <sys/types.h>
28: #include <errno.h>
1.76 deraadt 29: #include <signal.h>
1.75 stevesk 30: #include <stdio.h>
1.74 stevesk 31: #include <stdlib.h>
1.72 stevesk 32: #include <string.h>
1.143 djm 33: #include <unistd.h>
34: #include <poll.h>
1.1 markus 35:
1.99 markus 36: #ifdef WITH_OPENSSL
1.76 deraadt 37: #include <openssl/crypto.h>
1.99 markus 38: #endif
1.76 deraadt 39:
1.143 djm 40: #include "ssh.h"
1.1 markus 41: #include "ssh2.h"
1.143 djm 42: #include "atomicio.h"
43: #include "version.h"
1.7 markus 44: #include "packet.h"
1.1 markus 45: #include "compat.h"
1.18 markus 46: #include "cipher.h"
1.102 markus 47: #include "sshkey.h"
1.1 markus 48: #include "kex.h"
1.18 markus 49: #include "log.h"
1.21 markus 50: #include "mac.h"
1.23 markus 51: #include "match.h"
1.102 markus 52: #include "misc.h"
1.26 markus 53: #include "dispatch.h"
1.48 provos 54: #include "monitor.h"
1.102 markus 55:
56: #include "ssherr.h"
57: #include "sshbuf.h"
1.94 djm 58: #include "digest.h"
1.48 provos 59:
1.35 itojun 60: /* prototype */
1.102 markus 61: static int kex_choose_conf(struct ssh *);
1.133 markus 62: static int kex_input_newkeys(int, u_int32_t, struct ssh *);
1.86 djm 63:
1.110 djm 64: static const char *proposal_names[PROPOSAL_MAX] = {
65: "KEX algorithms",
66: "host key algorithms",
67: "ciphers ctos",
68: "ciphers stoc",
69: "MACs ctos",
70: "MACs stoc",
71: "compression ctos",
72: "compression stoc",
73: "languages ctos",
74: "languages stoc",
75: };
76:
1.89 djm 77: struct kexalg {
78: char *name;
1.102 markus 79: u_int type;
1.89 djm 80: int ec_nid;
1.94 djm 81: int hash_alg;
1.89 djm 82: };
83: static const struct kexalg kexalgs[] = {
1.99 markus 84: #ifdef WITH_OPENSSL
1.94 djm 85: { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
1.118 djm 86: { KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
87: { KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
88: { KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
89: { KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
1.94 djm 90: { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
91: { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
92: { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
93: NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
94: { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
95: SSH_DIGEST_SHA384 },
96: { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
97: SSH_DIGEST_SHA512 },
1.99 markus 98: #endif
1.94 djm 99: { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
1.124 djm 100: { KEX_CURVE25519_SHA256_OLD, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
1.147 djm 101: { KEX_SNTRUP4591761X25519_SHA512, KEX_KEM_SNTRUP4591761X25519_SHA512, 0,
102: SSH_DIGEST_SHA512 },
1.94 djm 103: { NULL, -1, -1, -1},
1.89 djm 104: };
105:
106: char *
1.93 dtucker 107: kex_alg_list(char sep)
1.89 djm 108: {
1.102 markus 109: char *ret = NULL, *tmp;
1.89 djm 110: size_t nlen, rlen = 0;
111: const struct kexalg *k;
112:
113: for (k = kexalgs; k->name != NULL; k++) {
114: if (ret != NULL)
1.93 dtucker 115: ret[rlen++] = sep;
1.89 djm 116: nlen = strlen(k->name);
1.102 markus 117: if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
118: free(ret);
119: return NULL;
120: }
121: ret = tmp;
1.89 djm 122: memcpy(ret + rlen, k->name, nlen + 1);
123: rlen += nlen;
124: }
125: return ret;
126: }
127:
128: static const struct kexalg *
129: kex_alg_by_name(const char *name)
130: {
131: const struct kexalg *k;
132:
133: for (k = kexalgs; k->name != NULL; k++) {
134: if (strcmp(k->name, name) == 0)
135: return k;
136: }
137: return NULL;
138: }
139:
1.86 djm 140: /* Validate KEX method name list */
141: int
142: kex_names_valid(const char *names)
143: {
144: char *s, *cp, *p;
145:
146: if (names == NULL || strcmp(names, "") == 0)
147: return 0;
1.102 markus 148: if ((s = cp = strdup(names)) == NULL)
149: return 0;
1.86 djm 150: for ((p = strsep(&cp, ",")); p && *p != '\0';
151: (p = strsep(&cp, ","))) {
1.89 djm 152: if (kex_alg_by_name(p) == NULL) {
1.86 djm 153: error("Unsupported KEX algorithm \"%.100s\"", p);
1.91 djm 154: free(s);
1.86 djm 155: return 0;
156: }
157: }
158: debug3("kex names ok: [%s]", names);
1.91 djm 159: free(s);
1.86 djm 160: return 1;
1.109 djm 161: }
162:
163: /*
164: * Concatenate algorithm names, avoiding duplicates in the process.
165: * Caller must free returned string.
166: */
167: char *
168: kex_names_cat(const char *a, const char *b)
169: {
1.129 dtucker 170: char *ret = NULL, *tmp = NULL, *cp, *p, *m;
1.109 djm 171: size_t len;
172:
173: if (a == NULL || *a == '\0')
1.138 djm 174: return strdup(b);
1.109 djm 175: if (b == NULL || *b == '\0')
176: return strdup(a);
177: if (strlen(b) > 1024*1024)
178: return NULL;
179: len = strlen(a) + strlen(b) + 2;
180: if ((tmp = cp = strdup(b)) == NULL ||
181: (ret = calloc(1, len)) == NULL) {
182: free(tmp);
183: return NULL;
184: }
185: strlcpy(ret, a, len);
186: for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
1.129 dtucker 187: if ((m = match_list(ret, p, NULL)) != NULL) {
188: free(m);
1.109 djm 189: continue; /* Algorithm already present */
1.129 dtucker 190: }
1.109 djm 191: if (strlcat(ret, ",", len) >= len ||
192: strlcat(ret, p, len) >= len) {
193: free(tmp);
194: free(ret);
195: return NULL; /* Shouldn't happen */
196: }
197: }
198: free(tmp);
199: return ret;
200: }
201:
202: /*
203: * Assemble a list of algorithms from a default list and a string from a
204: * configuration file. The user-provided string may begin with '+' to
1.128 djm 205: * indicate that it should be appended to the default or '-' that the
206: * specified names should be removed.
1.109 djm 207: */
208: int
1.138 djm 209: kex_assemble_names(char **listp, const char *def, const char *all)
1.109 djm 210: {
1.138 djm 211: char *cp, *tmp, *patterns;
212: char *list = NULL, *ret = NULL, *matching = NULL, *opatterns = NULL;
213: int r = SSH_ERR_INTERNAL_ERROR;
214:
215: if (listp == NULL || *listp == NULL || **listp == '\0') {
216: if ((*listp = strdup(def)) == NULL)
217: return SSH_ERR_ALLOC_FAIL;
218: return 0;
219: }
1.109 djm 220:
1.138 djm 221: list = *listp;
222: *listp = NULL;
223: if (*list == '+') {
224: /* Append names to default list */
225: if ((tmp = kex_names_cat(def, list + 1)) == NULL) {
226: r = SSH_ERR_ALLOC_FAIL;
227: goto fail;
228: }
229: free(list);
230: list = tmp;
231: } else if (*list == '-') {
232: /* Remove names from default list */
233: if ((*listp = match_filter_blacklist(def, list + 1)) == NULL) {
234: r = SSH_ERR_ALLOC_FAIL;
235: goto fail;
236: }
237: free(list);
238: /* filtering has already been done */
1.109 djm 239: return 0;
1.138 djm 240: } else {
241: /* Explicit list, overrides default - just use "list" as is */
242: }
243:
244: /*
245: * The supplied names may be a pattern-list. For the -list case,
246: * the patterns are applied above. For the +list and explicit list
247: * cases we need to do it now.
248: */
249: ret = NULL;
250: if ((patterns = opatterns = strdup(list)) == NULL) {
251: r = SSH_ERR_ALLOC_FAIL;
252: goto fail;
253: }
254: /* Apply positive (i.e. non-negated) patterns from the list */
255: while ((cp = strsep(&patterns, ",")) != NULL) {
256: if (*cp == '!') {
257: /* negated matches are not supported here */
258: r = SSH_ERR_INVALID_ARGUMENT;
259: goto fail;
260: }
261: free(matching);
262: if ((matching = match_filter_whitelist(all, cp)) == NULL) {
263: r = SSH_ERR_ALLOC_FAIL;
264: goto fail;
265: }
266: if ((tmp = kex_names_cat(ret, matching)) == NULL) {
267: r = SSH_ERR_ALLOC_FAIL;
268: goto fail;
269: }
270: free(ret);
271: ret = tmp;
1.109 djm 272: }
1.138 djm 273: if (ret == NULL || *ret == '\0') {
274: /* An empty name-list is an error */
275: /* XXX better error code? */
276: r = SSH_ERR_INVALID_ARGUMENT;
277: goto fail;
1.109 djm 278: }
279:
1.138 djm 280: /* success */
281: *listp = ret;
282: ret = NULL;
283: r = 0;
284:
285: fail:
286: free(matching);
287: free(opatterns);
288: free(list);
289: free(ret);
290: return r;
1.86 djm 291: }
1.26 markus 292:
293: /* put algorithm proposal into buffer */
1.102 markus 294: int
295: kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
1.1 markus 296: {
1.61 djm 297: u_int i;
1.102 markus 298: int r;
299:
300: sshbuf_reset(b);
1.26 markus 301:
1.49 markus 302: /*
303: * add a dummy cookie, the cookie will be overwritten by
304: * kex_send_kexinit(), each time a kexinit is set
305: */
1.102 markus 306: for (i = 0; i < KEX_COOKIE_LEN; i++) {
307: if ((r = sshbuf_put_u8(b, 0)) != 0)
308: return r;
309: }
310: for (i = 0; i < PROPOSAL_MAX; i++) {
311: if ((r = sshbuf_put_cstring(b, proposal[i])) != 0)
312: return r;
313: }
314: if ((r = sshbuf_put_u8(b, 0)) != 0 || /* first_kex_packet_follows */
315: (r = sshbuf_put_u32(b, 0)) != 0) /* uint32 reserved */
316: return r;
317: return 0;
1.1 markus 318: }
319:
1.26 markus 320: /* parse buffer and return algorithm proposal */
1.102 markus 321: int
322: kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
1.7 markus 323: {
1.102 markus 324: struct sshbuf *b = NULL;
325: u_char v;
1.78 djm 326: u_int i;
1.102 markus 327: char **proposal = NULL;
328: int r;
1.7 markus 329:
1.102 markus 330: *propp = NULL;
331: if ((proposal = calloc(PROPOSAL_MAX, sizeof(char *))) == NULL)
332: return SSH_ERR_ALLOC_FAIL;
333: if ((b = sshbuf_fromb(raw)) == NULL) {
334: r = SSH_ERR_ALLOC_FAIL;
335: goto out;
336: }
1.152 ! djm 337: if ((r = sshbuf_consume(b, KEX_COOKIE_LEN)) != 0) { /* skip cookie */
! 338: error("%s: consume cookie: %s", __func__, ssh_err(r));
1.102 markus 339: goto out;
1.152 ! djm 340: }
1.7 markus 341: /* extract kex init proposal strings */
342: for (i = 0; i < PROPOSAL_MAX; i++) {
1.152 ! djm 343: if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0) {
! 344: error("%s: parse proposal %u: %s", __func__,
! 345: i, ssh_err(r));
1.102 markus 346: goto out;
1.152 ! djm 347: }
1.110 djm 348: debug2("%s: %s", proposal_names[i], proposal[i]);
1.7 markus 349: }
1.26 markus 350: /* first kex follows / reserved */
1.115 djm 351: if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
1.152 ! djm 352: (r = sshbuf_get_u32(b, &i)) != 0) { /* reserved */
! 353: error("%s: parse: %s", __func__, ssh_err(r));
1.102 markus 354: goto out;
1.152 ! djm 355: }
1.53 markus 356: if (first_kex_follows != NULL)
1.115 djm 357: *first_kex_follows = v;
1.110 djm 358: debug2("first_kex_follows %d ", v);
359: debug2("reserved %u ", i);
1.102 markus 360: r = 0;
361: *propp = proposal;
362: out:
363: if (r != 0 && proposal != NULL)
364: kex_prop_free(proposal);
365: sshbuf_free(b);
366: return r;
1.1 markus 367: }
368:
1.102 markus 369: void
1.26 markus 370: kex_prop_free(char **proposal)
1.1 markus 371: {
1.61 djm 372: u_int i;
1.26 markus 373:
1.106 djm 374: if (proposal == NULL)
375: return;
1.26 markus 376: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 djm 377: free(proposal[i]);
378: free(proposal);
1.1 markus 379: }
380:
1.78 djm 381: /* ARGSUSED */
1.101 markus 382: static int
1.133 markus 383: kex_protocol_error(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 384: {
1.112 djm 385: int r;
386:
387: error("kex protocol error: type %d seq %u", type, seq);
388: if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
389: (r = sshpkt_put_u32(ssh, seq)) != 0 ||
390: (r = sshpkt_send(ssh)) != 0)
391: return r;
1.101 markus 392: return 0;
1.26 markus 393: }
1.1 markus 394:
1.35 itojun 395: static void
1.102 markus 396: kex_reset_dispatch(struct ssh *ssh)
1.29 markus 397: {
1.102 markus 398: ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
1.42 markus 399: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.29 markus 400: }
401:
1.113 markus 402: static int
403: kex_send_ext_info(struct ssh *ssh)
404: {
405: int r;
1.121 djm 406: char *algs;
1.113 markus 407:
1.151 djm 408: debug("Sending SSH2_MSG_EXT_INFO");
1.130 djm 409: if ((algs = sshkey_alg_list(0, 1, 1, ',')) == NULL)
1.121 djm 410: return SSH_ERR_ALLOC_FAIL;
1.137 djm 411: /* XXX filter algs list by allowed pubkey/hostbased types */
1.113 markus 412: if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
413: (r = sshpkt_put_u32(ssh, 1)) != 0 ||
414: (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 ||
1.121 djm 415: (r = sshpkt_put_cstring(ssh, algs)) != 0 ||
1.152 ! djm 416: (r = sshpkt_send(ssh)) != 0) {
! 417: error("%s: compose: %s", __func__, ssh_err(r));
1.121 djm 418: goto out;
1.152 ! djm 419: }
1.121 djm 420: /* success */
421: r = 0;
422: out:
423: free(algs);
1.123 djm 424: return r;
1.113 markus 425: }
426:
1.102 markus 427: int
428: kex_send_newkeys(struct ssh *ssh)
1.26 markus 429: {
1.102 markus 430: int r;
1.28 markus 431:
1.102 markus 432: kex_reset_dispatch(ssh);
433: if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
434: (r = sshpkt_send(ssh)) != 0)
435: return r;
1.26 markus 436: debug("SSH2_MSG_NEWKEYS sent");
1.102 markus 437: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
1.151 djm 438: if (ssh->kex->ext_info_c && (ssh->kex->flags & KEX_INITIAL) != 0)
1.113 markus 439: if ((r = kex_send_ext_info(ssh)) != 0)
440: return r;
1.151 djm 441: debug("expecting SSH2_MSG_NEWKEYS");
1.102 markus 442: return 0;
443: }
444:
1.113 markus 445: int
1.133 markus 446: kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
1.113 markus 447: {
448: struct kex *kex = ssh->kex;
449: u_int32_t i, ninfo;
1.137 djm 450: char *name;
1.134 djm 451: u_char *val;
452: size_t vlen;
1.113 markus 453: int r;
454:
455: debug("SSH2_MSG_EXT_INFO received");
456: ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
457: if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
458: return r;
459: for (i = 0; i < ninfo; i++) {
460: if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
461: return r;
1.134 djm 462: if ((r = sshpkt_get_string(ssh, &val, &vlen)) != 0) {
1.113 markus 463: free(name);
464: return r;
465: }
466: if (strcmp(name, "server-sig-algs") == 0) {
1.134 djm 467: /* Ensure no \0 lurking in value */
468: if (memchr(val, '\0', vlen) != NULL) {
469: error("%s: nul byte in %s", __func__, name);
470: return SSH_ERR_INVALID_FORMAT;
471: }
472: debug("%s: %s=<%s>", __func__, name, val);
1.137 djm 473: kex->server_sig_algs = val;
474: val = NULL;
1.134 djm 475: } else
476: debug("%s: %s (unrecognised)", __func__, name);
1.113 markus 477: free(name);
478: free(val);
479: }
480: return sshpkt_get_end(ssh);
481: }
482:
1.102 markus 483: static int
1.133 markus 484: kex_input_newkeys(int type, u_int32_t seq, struct ssh *ssh)
1.102 markus 485: {
486: struct kex *kex = ssh->kex;
487: int r;
1.19 stevesk 488:
1.26 markus 489: debug("SSH2_MSG_NEWKEYS received");
1.102 markus 490: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
1.131 markus 491: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.102 markus 492: if ((r = sshpkt_get_end(ssh)) != 0)
1.122 markus 493: return r;
494: if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
1.102 markus 495: return r;
1.30 markus 496: kex->done = 1;
1.142 djm 497: kex->flags &= ~KEX_INITIAL;
1.102 markus 498: sshbuf_reset(kex->peer);
499: /* sshbuf_reset(kex->my); */
1.26 markus 500: kex->flags &= ~KEX_INIT_SENT;
1.91 djm 501: free(kex->name);
1.32 markus 502: kex->name = NULL;
1.102 markus 503: return 0;
1.26 markus 504: }
1.1 markus 505:
1.102 markus 506: int
507: kex_send_kexinit(struct ssh *ssh)
1.26 markus 508: {
1.49 markus 509: u_char *cookie;
1.102 markus 510: struct kex *kex = ssh->kex;
511: int r;
1.49 markus 512:
1.152 ! djm 513: if (kex == NULL) {
! 514: error("%s: no hex", __func__);
1.102 markus 515: return SSH_ERR_INTERNAL_ERROR;
1.152 ! djm 516: }
1.102 markus 517: if (kex->flags & KEX_INIT_SENT)
518: return 0;
1.30 markus 519: kex->done = 0;
1.49 markus 520:
521: /* generate a random cookie */
1.152 ! djm 522: if (sshbuf_len(kex->my) < KEX_COOKIE_LEN) {
! 523: error("%s: bad kex length: %zu < %d", __func__,
! 524: sshbuf_len(kex->my), KEX_COOKIE_LEN);
1.102 markus 525: return SSH_ERR_INVALID_FORMAT;
1.152 ! djm 526: }
! 527: if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL) {
! 528: error("%s: buffer error", __func__);
1.102 markus 529: return SSH_ERR_INTERNAL_ERROR;
1.152 ! djm 530: }
1.102 markus 531: arc4random_buf(cookie, KEX_COOKIE_LEN);
532:
533: if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
534: (r = sshpkt_putb(ssh, kex->my)) != 0 ||
1.152 ! djm 535: (r = sshpkt_send(ssh)) != 0) {
! 536: error("%s: compose reply: %s", __func__, ssh_err(r));
1.102 markus 537: return r;
1.152 ! djm 538: }
1.26 markus 539: debug("SSH2_MSG_KEXINIT sent");
540: kex->flags |= KEX_INIT_SENT;
1.102 markus 541: return 0;
1.1 markus 542: }
543:
1.78 djm 544: /* ARGSUSED */
1.101 markus 545: int
1.133 markus 546: kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
1.11 provos 547: {
1.102 markus 548: struct kex *kex = ssh->kex;
549: const u_char *ptr;
1.100 markus 550: u_int i;
551: size_t dlen;
1.102 markus 552: int r;
1.11 provos 553:
1.26 markus 554: debug("SSH2_MSG_KEXINIT received");
1.152 ! djm 555: if (kex == NULL) {
! 556: error("%s: no hex", __func__);
! 557: return SSH_ERR_INTERNAL_ERROR;
! 558: }
1.127 markus 559: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, NULL);
1.102 markus 560: ptr = sshpkt_ptr(ssh, &dlen);
561: if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
562: return r;
1.31 markus 563:
564: /* discard packet */
1.152 ! djm 565: for (i = 0; i < KEX_COOKIE_LEN; i++) {
! 566: if ((r = sshpkt_get_u8(ssh, NULL)) != 0) {
! 567: error("%s: discard cookie: %s", __func__, ssh_err(r));
1.102 markus 568: return r;
1.152 ! djm 569: }
! 570: }
! 571: for (i = 0; i < PROPOSAL_MAX; i++) {
! 572: if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
! 573: error("%s: discard proposal: %s", __func__, ssh_err(r));
1.102 markus 574: return r;
1.152 ! djm 575: }
! 576: }
1.87 djm 577: /*
578: * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
579: * KEX method has the server move first, but a server might be using
580: * a custom method or one that we otherwise don't support. We should
581: * be prepared to remember first_kex_follows here so we can eat a
582: * packet later.
583: * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
584: * for cases where the server *doesn't* go first. I guess we should
585: * ignore it when it is set for these cases, which is what we do now.
586: */
1.102 markus 587: if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
588: (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
589: (r = sshpkt_get_end(ssh)) != 0)
590: return r;
591:
592: if (!(kex->flags & KEX_INIT_SENT))
593: if ((r = kex_send_kexinit(ssh)) != 0)
594: return r;
595: if ((r = kex_choose_conf(ssh)) != 0)
596: return r;
1.19 stevesk 597:
1.102 markus 598: if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
599: return (kex->kex[kex->kex_type])(ssh);
600:
1.152 ! djm 601: error("%s: unknown kex type %u", __func__, kex->kex_type);
1.102 markus 602: return SSH_ERR_INTERNAL_ERROR;
603: }
604:
1.143 djm 605: struct kex *
606: kex_new(void)
1.102 markus 607: {
608: struct kex *kex;
609:
1.143 djm 610: if ((kex = calloc(1, sizeof(*kex))) == NULL ||
611: (kex->peer = sshbuf_new()) == NULL ||
612: (kex->my = sshbuf_new()) == NULL ||
613: (kex->client_version = sshbuf_new()) == NULL ||
614: (kex->server_version = sshbuf_new()) == NULL) {
615: kex_free(kex);
616: return NULL;
1.102 markus 617: }
1.143 djm 618: return kex;
1.26 markus 619: }
1.11 provos 620:
1.100 markus 621: void
622: kex_free_newkeys(struct newkeys *newkeys)
623: {
624: if (newkeys == NULL)
625: return;
626: if (newkeys->enc.key) {
627: explicit_bzero(newkeys->enc.key, newkeys->enc.key_len);
628: free(newkeys->enc.key);
629: newkeys->enc.key = NULL;
630: }
631: if (newkeys->enc.iv) {
1.111 djm 632: explicit_bzero(newkeys->enc.iv, newkeys->enc.iv_len);
1.100 markus 633: free(newkeys->enc.iv);
634: newkeys->enc.iv = NULL;
635: }
636: free(newkeys->enc.name);
637: explicit_bzero(&newkeys->enc, sizeof(newkeys->enc));
638: free(newkeys->comp.name);
639: explicit_bzero(&newkeys->comp, sizeof(newkeys->comp));
640: mac_clear(&newkeys->mac);
641: if (newkeys->mac.key) {
642: explicit_bzero(newkeys->mac.key, newkeys->mac.key_len);
643: free(newkeys->mac.key);
644: newkeys->mac.key = NULL;
645: }
646: free(newkeys->mac.name);
647: explicit_bzero(&newkeys->mac, sizeof(newkeys->mac));
648: explicit_bzero(newkeys, sizeof(*newkeys));
649: free(newkeys);
650: }
651:
1.102 markus 652: void
653: kex_free(struct kex *kex)
1.26 markus 654: {
1.102 markus 655: u_int mode;
1.11 provos 656:
1.143 djm 657: if (kex == NULL)
658: return;
659:
1.102 markus 660: #ifdef WITH_OPENSSL
1.136 jsing 661: DH_free(kex->dh);
662: EC_KEY_free(kex->ec_client_key);
1.102 markus 663: #endif
664: for (mode = 0; mode < MODE_MAX; mode++) {
665: kex_free_newkeys(kex->newkeys[mode]);
666: kex->newkeys[mode] = NULL;
1.100 markus 667: }
1.102 markus 668: sshbuf_free(kex->peer);
669: sshbuf_free(kex->my);
1.143 djm 670: sshbuf_free(kex->client_version);
671: sshbuf_free(kex->server_version);
1.149 djm 672: sshbuf_free(kex->client_pub);
1.102 markus 673: free(kex->session_id);
1.107 djm 674: free(kex->failed_choice);
1.113 markus 675: free(kex->hostkey_alg);
676: free(kex->name);
1.102 markus 677: free(kex);
1.11 provos 678: }
679:
1.102 markus 680: int
1.143 djm 681: kex_ready(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
682: {
683: int r;
684:
685: if ((r = kex_prop2buf(ssh->kex->my, proposal)) != 0)
686: return r;
687: ssh->kex->flags = KEX_INITIAL;
688: kex_reset_dispatch(ssh);
689: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
690: return 0;
691: }
692:
693: int
1.102 markus 694: kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
1.1 markus 695: {
1.102 markus 696: int r;
1.1 markus 697:
1.143 djm 698: if ((r = kex_ready(ssh, proposal)) != 0)
1.102 markus 699: return r;
700: if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
701: kex_free(ssh->kex);
702: ssh->kex = NULL;
703: return r;
1.1 markus 704: }
1.102 markus 705: return 0;
1.117 djm 706: }
707:
708: /*
709: * Request key re-exchange, returns 0 on success or a ssherr.h error
710: * code otherwise. Must not be called if KEX is incomplete or in-progress.
711: */
712: int
713: kex_start_rekex(struct ssh *ssh)
714: {
715: if (ssh->kex == NULL) {
716: error("%s: no kex", __func__);
717: return SSH_ERR_INTERNAL_ERROR;
718: }
719: if (ssh->kex->done == 0) {
720: error("%s: requested twice", __func__);
721: return SSH_ERR_INTERNAL_ERROR;
722: }
723: ssh->kex->done = 0;
724: return kex_send_kexinit(ssh);
1.1 markus 725: }
726:
1.102 markus 727: static int
728: choose_enc(struct sshenc *enc, char *client, char *server)
1.1 markus 729: {
1.23 markus 730: char *name = match_list(client, server, NULL);
1.102 markus 731:
1.1 markus 732: if (name == NULL)
1.102 markus 733: return SSH_ERR_NO_CIPHER_ALG_MATCH;
1.129 dtucker 734: if ((enc->cipher = cipher_by_name(name)) == NULL) {
1.152 ! djm 735: error("%s: unsupported cipher %s", __func__, name);
1.129 dtucker 736: free(name);
1.102 markus 737: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 738: }
1.1 markus 739: enc->name = name;
740: enc->enabled = 0;
741: enc->iv = NULL;
1.88 markus 742: enc->iv_len = cipher_ivlen(enc->cipher);
1.1 markus 743: enc->key = NULL;
1.45 markus 744: enc->key_len = cipher_keylen(enc->cipher);
745: enc->block_size = cipher_blocksize(enc->cipher);
1.102 markus 746: return 0;
1.1 markus 747: }
1.69 deraadt 748:
1.102 markus 749: static int
750: choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
1.1 markus 751: {
1.23 markus 752: char *name = match_list(client, server, NULL);
1.102 markus 753:
1.1 markus 754: if (name == NULL)
1.102 markus 755: return SSH_ERR_NO_MAC_ALG_MATCH;
1.129 dtucker 756: if (mac_setup(mac, name) < 0) {
1.152 ! djm 757: error("%s: unsupported MAC %s", __func__, name);
1.129 dtucker 758: free(name);
1.102 markus 759: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 760: }
1.1 markus 761: mac->name = name;
762: mac->key = NULL;
763: mac->enabled = 0;
1.102 markus 764: return 0;
1.1 markus 765: }
1.69 deraadt 766:
1.102 markus 767: static int
768: choose_comp(struct sshcomp *comp, char *client, char *server)
1.1 markus 769: {
1.23 markus 770: char *name = match_list(client, server, NULL);
1.102 markus 771:
1.1 markus 772: if (name == NULL)
1.102 markus 773: return SSH_ERR_NO_COMPRESS_ALG_MATCH;
1.64 markus 774: if (strcmp(name, "zlib@openssh.com") == 0) {
1.141 sf 775: comp->type = COMP_DELAYED;
776: } else if (strcmp(name, "zlib") == 0) {
1.140 sf 777: comp->type = COMP_ZLIB;
1.1 markus 778: } else if (strcmp(name, "none") == 0) {
1.64 markus 779: comp->type = COMP_NONE;
1.1 markus 780: } else {
1.152 ! djm 781: error("%s: unsupported compression scheme %s", __func__, name);
1.129 dtucker 782: free(name);
1.102 markus 783: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 784: }
785: comp->name = name;
1.102 markus 786: return 0;
1.1 markus 787: }
1.69 deraadt 788:
1.102 markus 789: static int
790: choose_kex(struct kex *k, char *client, char *server)
1.1 markus 791: {
1.89 djm 792: const struct kexalg *kexalg;
793:
1.23 markus 794: k->name = match_list(client, server, NULL);
1.102 markus 795:
1.110 djm 796: debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
1.1 markus 797: if (k->name == NULL)
1.102 markus 798: return SSH_ERR_NO_KEX_ALG_MATCH;
1.152 ! djm 799: if ((kexalg = kex_alg_by_name(k->name)) == NULL) {
! 800: error("%s: unsupported KEX method %s", __func__, k->name);
1.102 markus 801: return SSH_ERR_INTERNAL_ERROR;
1.152 ! djm 802: }
1.89 djm 803: k->kex_type = kexalg->type;
1.94 djm 804: k->hash_alg = kexalg->hash_alg;
1.89 djm 805: k->ec_nid = kexalg->ec_nid;
1.102 markus 806: return 0;
1.1 markus 807: }
1.65 djm 808:
1.102 markus 809: static int
810: choose_hostkeyalg(struct kex *k, char *client, char *server)
1.1 markus 811: {
1.113 markus 812: k->hostkey_alg = match_list(client, server, NULL);
1.102 markus 813:
1.110 djm 814: debug("kex: host key algorithm: %s",
1.113 markus 815: k->hostkey_alg ? k->hostkey_alg : "(no match)");
816: if (k->hostkey_alg == NULL)
1.102 markus 817: return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
1.113 markus 818: k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
1.152 ! djm 819: if (k->hostkey_type == KEY_UNSPEC) {
! 820: error("%s: unsupported hostkey algorithm %s", __func__,
! 821: k->hostkey_alg);
1.102 markus 822: return SSH_ERR_INTERNAL_ERROR;
1.152 ! djm 823: }
1.113 markus 824: k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
1.102 markus 825: return 0;
1.1 markus 826: }
827:
1.56 djm 828: static int
1.53 markus 829: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
830: {
831: static int check[] = {
832: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
833: };
834: int *idx;
835: char *p;
836:
837: for (idx = &check[0]; *idx != -1; idx++) {
838: if ((p = strchr(my[*idx], ',')) != NULL)
839: *p = '\0';
840: if ((p = strchr(peer[*idx], ',')) != NULL)
841: *p = '\0';
842: if (strcmp(my[*idx], peer[*idx]) != 0) {
843: debug2("proposal mismatch: my %s peer %s",
844: my[*idx], peer[*idx]);
845: return (0);
846: }
847: }
848: debug2("proposals match");
849: return (1);
850: }
851:
1.102 markus 852: static int
853: kex_choose_conf(struct ssh *ssh)
1.1 markus 854: {
1.102 markus 855: struct kex *kex = ssh->kex;
856: struct newkeys *newkeys;
857: char **my = NULL, **peer = NULL;
1.26 markus 858: char **cprop, **sprop;
1.27 markus 859: int nenc, nmac, ncomp;
1.96 dtucker 860: u_int mode, ctos, need, dh_need, authlen;
1.102 markus 861: int r, first_kex_follows;
1.1 markus 862:
1.110 djm 863: debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
864: if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
865: goto out;
866: debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
867: if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
1.102 markus 868: goto out;
1.26 markus 869:
1.27 markus 870: if (kex->server) {
1.26 markus 871: cprop=peer;
872: sprop=my;
873: } else {
874: cprop=my;
875: sprop=peer;
1.113 markus 876: }
877:
878: /* Check whether client supports ext_info_c */
1.142 djm 879: if (kex->server && (kex->flags & KEX_INITIAL)) {
1.113 markus 880: char *ext;
881:
882: ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
1.119 markus 883: kex->ext_info_c = (ext != NULL);
884: free(ext);
1.26 markus 885: }
1.1 markus 886:
1.30 markus 887: /* Algorithm Negotiation */
1.110 djm 888: if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
889: sprop[PROPOSAL_KEX_ALGS])) != 0) {
890: kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
891: peer[PROPOSAL_KEX_ALGS] = NULL;
892: goto out;
893: }
894: if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
895: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
896: kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
897: peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
898: goto out;
899: }
1.1 markus 900: for (mode = 0; mode < MODE_MAX; mode++) {
1.102 markus 901: if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
902: r = SSH_ERR_ALLOC_FAIL;
903: goto out;
904: }
1.30 markus 905: kex->newkeys[mode] = newkeys;
1.78 djm 906: ctos = (!kex->server && mode == MODE_OUT) ||
907: (kex->server && mode == MODE_IN);
1.1 markus 908: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
909: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
910: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.102 markus 911: if ((r = choose_enc(&newkeys->enc, cprop[nenc],
1.107 djm 912: sprop[nenc])) != 0) {
913: kex->failed_choice = peer[nenc];
914: peer[nenc] = NULL;
1.102 markus 915: goto out;
1.107 djm 916: }
1.102 markus 917: authlen = cipher_authlen(newkeys->enc.cipher);
1.88 markus 918: /* ignore mac for authenticated encryption */
1.102 markus 919: if (authlen == 0 &&
920: (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
1.107 djm 921: sprop[nmac])) != 0) {
922: kex->failed_choice = peer[nmac];
923: peer[nmac] = NULL;
1.102 markus 924: goto out;
1.107 djm 925: }
1.102 markus 926: if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
1.107 djm 927: sprop[ncomp])) != 0) {
928: kex->failed_choice = peer[ncomp];
929: peer[ncomp] = NULL;
1.102 markus 930: goto out;
1.107 djm 931: }
1.110 djm 932: debug("kex: %s cipher: %s MAC: %s compression: %s",
1.1 markus 933: ctos ? "client->server" : "server->client",
1.27 markus 934: newkeys->enc.name,
1.88 markus 935: authlen == 0 ? newkeys->mac.name : "<implicit>",
1.27 markus 936: newkeys->comp.name);
1.107 djm 937: }
1.96 dtucker 938: need = dh_need = 0;
1.1 markus 939: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 940: newkeys = kex->newkeys[mode];
1.120 deraadt 941: need = MAXIMUM(need, newkeys->enc.key_len);
942: need = MAXIMUM(need, newkeys->enc.block_size);
943: need = MAXIMUM(need, newkeys->enc.iv_len);
944: need = MAXIMUM(need, newkeys->mac.key_len);
945: dh_need = MAXIMUM(dh_need, cipher_seclen(newkeys->enc.cipher));
946: dh_need = MAXIMUM(dh_need, newkeys->enc.block_size);
947: dh_need = MAXIMUM(dh_need, newkeys->enc.iv_len);
948: dh_need = MAXIMUM(dh_need, newkeys->mac.key_len);
1.1 markus 949: }
1.7 markus 950: /* XXX need runden? */
1.27 markus 951: kex->we_need = need;
1.96 dtucker 952: kex->dh_need = dh_need;
1.53 markus 953:
954: /* ignore the next message if the proposals do not match */
1.135 djm 955: if (first_kex_follows && !proposals_match(my, peer))
1.102 markus 956: ssh->dispatch_skip_packets = 1;
957: r = 0;
958: out:
1.26 markus 959: kex_prop_free(my);
960: kex_prop_free(peer);
1.102 markus 961: return r;
1.26 markus 962: }
963:
1.102 markus 964: static int
965: derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
966: const struct sshbuf *shared_secret, u_char **keyp)
1.26 markus 967: {
1.102 markus 968: struct kex *kex = ssh->kex;
969: struct ssh_digest_ctx *hashctx = NULL;
1.26 markus 970: char c = id;
1.61 djm 971: u_int have;
1.94 djm 972: size_t mdsz;
1.61 djm 973: u_char *digest;
1.102 markus 974: int r;
1.62 djm 975:
1.94 djm 976: if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
1.102 markus 977: return SSH_ERR_INVALID_ARGUMENT;
1.120 deraadt 978: if ((digest = calloc(1, ROUNDUP(need, mdsz))) == NULL) {
1.102 markus 979: r = SSH_ERR_ALLOC_FAIL;
980: goto out;
981: }
1.26 markus 982:
1.30 markus 983: /* K1 = HASH(K || H || "A" || session_id) */
1.102 markus 984: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
985: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 986: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
987: ssh_digest_update(hashctx, &c, 1) != 0 ||
988: ssh_digest_update(hashctx, kex->session_id,
1.102 markus 989: kex->session_id_len) != 0 ||
990: ssh_digest_final(hashctx, digest, mdsz) != 0) {
991: r = SSH_ERR_LIBCRYPTO_ERROR;
1.152 ! djm 992: error("%s: KEX hash failed", __func__);
1.102 markus 993: goto out;
994: }
1.94 djm 995: ssh_digest_free(hashctx);
1.102 markus 996: hashctx = NULL;
1.26 markus 997:
1.30 markus 998: /*
999: * expand key:
1000: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
1001: * Key = K1 || K2 || ... || Kn
1002: */
1.26 markus 1003: for (have = mdsz; need > have; have += mdsz) {
1.102 markus 1004: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1005: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 1006: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1.102 markus 1007: ssh_digest_update(hashctx, digest, have) != 0 ||
1008: ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
1.152 ! djm 1009: error("%s: KDF failed", __func__);
1.102 markus 1010: r = SSH_ERR_LIBCRYPTO_ERROR;
1011: goto out;
1012: }
1.94 djm 1013: ssh_digest_free(hashctx);
1.102 markus 1014: hashctx = NULL;
1.26 markus 1015: }
1016: #ifdef DEBUG_KEX
1017: fprintf(stderr, "key '%c'== ", c);
1018: dump_digest("key", digest, need);
1019: #endif
1.102 markus 1020: *keyp = digest;
1021: digest = NULL;
1022: r = 0;
1023: out:
1.114 mmcc 1024: free(digest);
1.102 markus 1025: ssh_digest_free(hashctx);
1026: return r;
1.1 markus 1027: }
1028:
1.23 markus 1029: #define NKEYS 6
1.102 markus 1030: int
1031: kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
1032: const struct sshbuf *shared_secret)
1.1 markus 1033: {
1.102 markus 1034: struct kex *kex = ssh->kex;
1.15 markus 1035: u_char *keys[NKEYS];
1.102 markus 1036: u_int i, j, mode, ctos;
1037: int r;
1.1 markus 1038:
1.144 djm 1039: /* save initial hash as session id */
1040: if (kex->session_id == NULL) {
1041: kex->session_id_len = hashlen;
1042: kex->session_id = malloc(kex->session_id_len);
1043: if (kex->session_id == NULL)
1044: return SSH_ERR_ALLOC_FAIL;
1045: memcpy(kex->session_id, hash, kex->session_id_len);
1046: }
1.65 djm 1047: for (i = 0; i < NKEYS; i++) {
1.102 markus 1048: if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
1049: shared_secret, &keys[i])) != 0) {
1050: for (j = 0; j < i; j++)
1051: free(keys[j]);
1052: return r;
1053: }
1.65 djm 1054: }
1.1 markus 1055: for (mode = 0; mode < MODE_MAX; mode++) {
1.69 deraadt 1056: ctos = (!kex->server && mode == MODE_OUT) ||
1057: (kex->server && mode == MODE_IN);
1.100 markus 1058: kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
1059: kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
1060: kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 1061: }
1.102 markus 1062: return 0;
1.95 djm 1063: }
1.57 djm 1064:
1.145 djm 1065: int
1.150 djm 1066: kex_load_hostkey(struct ssh *ssh, struct sshkey **prvp, struct sshkey **pubp)
1.145 djm 1067: {
1068: struct kex *kex = ssh->kex;
1069:
1070: *pubp = NULL;
1071: *prvp = NULL;
1072: if (kex->load_host_public_key == NULL ||
1.152 ! djm 1073: kex->load_host_private_key == NULL) {
! 1074: error("%s: missing hostkey loader", __func__);
1.145 djm 1075: return SSH_ERR_INVALID_ARGUMENT;
1.152 ! djm 1076: }
1.145 djm 1077: *pubp = kex->load_host_public_key(kex->hostkey_type,
1078: kex->hostkey_nid, ssh);
1079: *prvp = kex->load_host_private_key(kex->hostkey_type,
1080: kex->hostkey_nid, ssh);
1081: if (*pubp == NULL)
1082: return SSH_ERR_NO_HOSTKEY_LOADED;
1.146 djm 1083: return 0;
1084: }
1085:
1086: int
1087: kex_verify_host_key(struct ssh *ssh, struct sshkey *server_host_key)
1088: {
1089: struct kex *kex = ssh->kex;
1090:
1.152 ! djm 1091: if (kex->verify_host_key == NULL) {
! 1092: error("%s: missing hostkey verifier", __func__);
1.146 djm 1093: return SSH_ERR_INVALID_ARGUMENT;
1.152 ! djm 1094: }
1.146 djm 1095: if (server_host_key->type != kex->hostkey_type ||
1096: (kex->hostkey_type == KEY_ECDSA &&
1097: server_host_key->ecdsa_nid != kex->hostkey_nid))
1098: return SSH_ERR_KEY_TYPE_MISMATCH;
1099: if (kex->verify_host_key(server_host_key, ssh) == -1)
1100: return SSH_ERR_SIGNATURE_INVALID;
1.145 djm 1101: return 0;
1102: }
1.26 markus 1103:
1.84 djm 1104: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1.26 markus 1105: void
1.147 djm 1106: dump_digest(const char *msg, const u_char *digest, int len)
1.26 markus 1107: {
1108: fprintf(stderr, "%s\n", msg);
1.102 markus 1109: sshbuf_dump_data(digest, len, stderr);
1.26 markus 1110: }
1111: #endif
1.143 djm 1112:
1113: /*
1114: * Send a plaintext error message to the peer, suffixed by \r\n.
1115: * Only used during banner exchange, and there only for the server.
1116: */
1117: static void
1118: send_error(struct ssh *ssh, char *msg)
1119: {
1120: char *crnl = "\r\n";
1121:
1122: if (!ssh->kex->server)
1123: return;
1124:
1125: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1126: msg, strlen(msg)) != strlen(msg) ||
1127: atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1128: crnl, strlen(crnl)) != strlen(crnl))
1129: error("%s: write: %.100s", __func__, strerror(errno));
1130: }
1131:
1132: /*
1133: * Sends our identification string and waits for the peer's. Will block for
1134: * up to timeout_ms (or indefinitely if timeout_ms <= 0).
1135: * Returns on 0 success or a ssherr.h code on failure.
1136: */
1137: int
1138: kex_exchange_identification(struct ssh *ssh, int timeout_ms,
1139: const char *version_addendum)
1140: {
1141: int remote_major, remote_minor, mismatch;
1142: size_t len, i, n;
1143: int r, expect_nl;
1144: u_char c;
1145: struct sshbuf *our_version = ssh->kex->server ?
1146: ssh->kex->server_version : ssh->kex->client_version;
1147: struct sshbuf *peer_version = ssh->kex->server ?
1148: ssh->kex->client_version : ssh->kex->server_version;
1149: char *our_version_string = NULL, *peer_version_string = NULL;
1150: char *cp, *remote_version = NULL;
1151:
1152: /* Prepare and send our banner */
1153: sshbuf_reset(our_version);
1154: if (version_addendum != NULL && *version_addendum == '\0')
1155: version_addendum = NULL;
1156: if ((r = sshbuf_putf(our_version, "SSH-%d.%d-%.100s%s%s\r\n",
1157: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
1158: version_addendum == NULL ? "" : " ",
1159: version_addendum == NULL ? "" : version_addendum)) != 0) {
1160: error("%s: sshbuf_putf: %s", __func__, ssh_err(r));
1161: goto out;
1162: }
1163:
1164: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1165: sshbuf_mutable_ptr(our_version),
1166: sshbuf_len(our_version)) != sshbuf_len(our_version)) {
1167: error("%s: write: %.100s", __func__, strerror(errno));
1168: r = SSH_ERR_SYSTEM_ERROR;
1169: goto out;
1170: }
1171: if ((r = sshbuf_consume_end(our_version, 2)) != 0) { /* trim \r\n */
1172: error("%s: sshbuf_consume_end: %s", __func__, ssh_err(r));
1173: goto out;
1174: }
1175: our_version_string = sshbuf_dup_string(our_version);
1176: if (our_version_string == NULL) {
1177: error("%s: sshbuf_dup_string failed", __func__);
1178: r = SSH_ERR_ALLOC_FAIL;
1179: goto out;
1180: }
1181: debug("Local version string %.100s", our_version_string);
1182:
1183: /* Read other side's version identification. */
1184: for (n = 0; ; n++) {
1185: if (n >= SSH_MAX_PRE_BANNER_LINES) {
1186: send_error(ssh, "No SSH identification string "
1187: "received.");
1188: error("%s: No SSH version received in first %u lines "
1189: "from server", __func__, SSH_MAX_PRE_BANNER_LINES);
1190: r = SSH_ERR_INVALID_FORMAT;
1191: goto out;
1192: }
1193: sshbuf_reset(peer_version);
1194: expect_nl = 0;
1195: for (i = 0; ; i++) {
1196: if (timeout_ms > 0) {
1197: r = waitrfd(ssh_packet_get_connection_in(ssh),
1198: &timeout_ms);
1199: if (r == -1 && errno == ETIMEDOUT) {
1200: send_error(ssh, "Timed out waiting "
1201: "for SSH identification string.");
1202: error("Connection timed out during "
1203: "banner exchange");
1204: r = SSH_ERR_CONN_TIMEOUT;
1205: goto out;
1206: } else if (r == -1) {
1207: error("%s: %s",
1208: __func__, strerror(errno));
1209: r = SSH_ERR_SYSTEM_ERROR;
1210: goto out;
1211: }
1212: }
1213:
1214: len = atomicio(read, ssh_packet_get_connection_in(ssh),
1215: &c, 1);
1216: if (len != 1 && errno == EPIPE) {
1217: error("%s: Connection closed by remote host",
1218: __func__);
1219: r = SSH_ERR_CONN_CLOSED;
1220: goto out;
1221: } else if (len != 1) {
1222: error("%s: read: %.100s",
1223: __func__, strerror(errno));
1224: r = SSH_ERR_SYSTEM_ERROR;
1225: goto out;
1226: }
1227: if (c == '\r') {
1228: expect_nl = 1;
1229: continue;
1230: }
1231: if (c == '\n')
1232: break;
1233: if (c == '\0' || expect_nl) {
1234: error("%s: banner line contains invalid "
1235: "characters", __func__);
1236: goto invalid;
1237: }
1238: if ((r = sshbuf_put_u8(peer_version, c)) != 0) {
1239: error("%s: sshbuf_put: %s",
1240: __func__, ssh_err(r));
1241: goto out;
1242: }
1243: if (sshbuf_len(peer_version) > SSH_MAX_BANNER_LEN) {
1244: error("%s: banner line too long", __func__);
1245: goto invalid;
1246: }
1247: }
1248: /* Is this an actual protocol banner? */
1249: if (sshbuf_len(peer_version) > 4 &&
1250: memcmp(sshbuf_ptr(peer_version), "SSH-", 4) == 0)
1251: break;
1252: /* If not, then just log the line and continue */
1253: if ((cp = sshbuf_dup_string(peer_version)) == NULL) {
1254: error("%s: sshbuf_dup_string failed", __func__);
1255: r = SSH_ERR_ALLOC_FAIL;
1256: goto out;
1257: }
1258: /* Do not accept lines before the SSH ident from a client */
1259: if (ssh->kex->server) {
1260: error("%s: client sent invalid protocol identifier "
1261: "\"%.256s\"", __func__, cp);
1262: free(cp);
1263: goto invalid;
1264: }
1265: debug("%s: banner line %zu: %s", __func__, n, cp);
1266: free(cp);
1267: }
1268: peer_version_string = sshbuf_dup_string(peer_version);
1269: if (peer_version_string == NULL)
1270: error("%s: sshbuf_dup_string failed", __func__);
1271: /* XXX must be same size for sscanf */
1272: if ((remote_version = calloc(1, sshbuf_len(peer_version))) == NULL) {
1273: error("%s: calloc failed", __func__);
1274: r = SSH_ERR_ALLOC_FAIL;
1275: goto out;
1276: }
1277:
1278: /*
1279: * Check that the versions match. In future this might accept
1280: * several versions and set appropriate flags to handle them.
1281: */
1282: if (sscanf(peer_version_string, "SSH-%d.%d-%[^\n]\n",
1283: &remote_major, &remote_minor, remote_version) != 3) {
1284: error("Bad remote protocol version identification: '%.100s'",
1285: peer_version_string);
1286: invalid:
1287: send_error(ssh, "Invalid SSH identification string.");
1288: r = SSH_ERR_INVALID_FORMAT;
1289: goto out;
1290: }
1291: debug("Remote protocol version %d.%d, remote software version %.100s",
1292: remote_major, remote_minor, remote_version);
1293: ssh->compat = compat_datafellows(remote_version);
1294:
1295: mismatch = 0;
1296: switch (remote_major) {
1297: case 2:
1298: break;
1299: case 1:
1300: if (remote_minor != 99)
1301: mismatch = 1;
1302: break;
1303: default:
1304: mismatch = 1;
1305: break;
1306: }
1307: if (mismatch) {
1308: error("Protocol major versions differ: %d vs. %d",
1309: PROTOCOL_MAJOR_2, remote_major);
1310: send_error(ssh, "Protocol major versions differ.");
1311: r = SSH_ERR_NO_PROTOCOL_VERSION;
1312: goto out;
1313: }
1314:
1315: if (ssh->kex->server && (ssh->compat & SSH_BUG_PROBE) != 0) {
1316: logit("probed from %s port %d with %s. Don't panic.",
1317: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1318: peer_version_string);
1319: r = SSH_ERR_CONN_CLOSED; /* XXX */
1320: goto out;
1321: }
1322: if (ssh->kex->server && (ssh->compat & SSH_BUG_SCANNER) != 0) {
1323: logit("scanned from %s port %d with %s. Don't panic.",
1324: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1325: peer_version_string);
1326: r = SSH_ERR_CONN_CLOSED; /* XXX */
1327: goto out;
1328: }
1329: if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
1330: logit("Remote version \"%.100s\" uses unsafe RSA signature "
1331: "scheme; disabling use of RSA keys", remote_version);
1332: }
1333: /* success */
1334: r = 0;
1335: out:
1336: free(our_version_string);
1337: free(peer_version_string);
1338: free(remote_version);
1339: return r;
1340: }
1341:
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