Annotation of src/usr.bin/ssh/kex.c, Revision 1.158
1.158 ! djm 1: /* $OpenBSD: kex.c,v 1.157 2020/02/26 13:40:09 jsg 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 },
1.155 dtucker 103: { NULL, 0, -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
1.154 naddy 205: * indicate that it should be appended to the default, '-' that the
206: * specified names should be removed, or '^' that they should be placed
207: * at the head.
1.109 djm 208: */
209: int
1.138 djm 210: kex_assemble_names(char **listp, const char *def, const char *all)
1.109 djm 211: {
1.138 djm 212: char *cp, *tmp, *patterns;
213: char *list = NULL, *ret = NULL, *matching = NULL, *opatterns = NULL;
214: int r = SSH_ERR_INTERNAL_ERROR;
215:
1.153 djm 216: if (listp == NULL || def == NULL || all == NULL)
217: return SSH_ERR_INVALID_ARGUMENT;
218:
219: if (*listp == NULL || **listp == '\0') {
1.138 djm 220: if ((*listp = strdup(def)) == NULL)
221: return SSH_ERR_ALLOC_FAIL;
222: return 0;
223: }
1.109 djm 224:
1.138 djm 225: list = *listp;
226: *listp = NULL;
227: if (*list == '+') {
228: /* Append names to default list */
229: if ((tmp = kex_names_cat(def, list + 1)) == NULL) {
230: r = SSH_ERR_ALLOC_FAIL;
231: goto fail;
232: }
233: free(list);
234: list = tmp;
235: } else if (*list == '-') {
236: /* Remove names from default list */
237: if ((*listp = match_filter_blacklist(def, list + 1)) == NULL) {
238: r = SSH_ERR_ALLOC_FAIL;
239: goto fail;
240: }
241: free(list);
242: /* filtering has already been done */
1.109 djm 243: return 0;
1.154 naddy 244: } else if (*list == '^') {
245: /* Place names at head of default list */
246: if ((tmp = kex_names_cat(list + 1, def)) == NULL) {
247: r = SSH_ERR_ALLOC_FAIL;
248: goto fail;
249: }
250: free(list);
251: list = tmp;
1.138 djm 252: } else {
253: /* Explicit list, overrides default - just use "list" as is */
254: }
255:
256: /*
257: * The supplied names may be a pattern-list. For the -list case,
258: * the patterns are applied above. For the +list and explicit list
259: * cases we need to do it now.
260: */
261: ret = NULL;
262: if ((patterns = opatterns = strdup(list)) == NULL) {
263: r = SSH_ERR_ALLOC_FAIL;
264: goto fail;
265: }
266: /* Apply positive (i.e. non-negated) patterns from the list */
267: while ((cp = strsep(&patterns, ",")) != NULL) {
268: if (*cp == '!') {
269: /* negated matches are not supported here */
270: r = SSH_ERR_INVALID_ARGUMENT;
271: goto fail;
272: }
273: free(matching);
274: if ((matching = match_filter_whitelist(all, cp)) == NULL) {
275: r = SSH_ERR_ALLOC_FAIL;
276: goto fail;
277: }
278: if ((tmp = kex_names_cat(ret, matching)) == NULL) {
279: r = SSH_ERR_ALLOC_FAIL;
280: goto fail;
281: }
282: free(ret);
283: ret = tmp;
1.109 djm 284: }
1.138 djm 285: if (ret == NULL || *ret == '\0') {
286: /* An empty name-list is an error */
287: /* XXX better error code? */
288: r = SSH_ERR_INVALID_ARGUMENT;
289: goto fail;
1.109 djm 290: }
291:
1.138 djm 292: /* success */
293: *listp = ret;
294: ret = NULL;
295: r = 0;
296:
297: fail:
298: free(matching);
299: free(opatterns);
300: free(list);
301: free(ret);
302: return r;
1.86 djm 303: }
1.26 markus 304:
305: /* put algorithm proposal into buffer */
1.102 markus 306: int
307: kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
1.1 markus 308: {
1.61 djm 309: u_int i;
1.102 markus 310: int r;
311:
312: sshbuf_reset(b);
1.26 markus 313:
1.49 markus 314: /*
315: * add a dummy cookie, the cookie will be overwritten by
316: * kex_send_kexinit(), each time a kexinit is set
317: */
1.102 markus 318: for (i = 0; i < KEX_COOKIE_LEN; i++) {
319: if ((r = sshbuf_put_u8(b, 0)) != 0)
320: return r;
321: }
322: for (i = 0; i < PROPOSAL_MAX; i++) {
323: if ((r = sshbuf_put_cstring(b, proposal[i])) != 0)
324: return r;
325: }
326: if ((r = sshbuf_put_u8(b, 0)) != 0 || /* first_kex_packet_follows */
327: (r = sshbuf_put_u32(b, 0)) != 0) /* uint32 reserved */
328: return r;
329: return 0;
1.1 markus 330: }
331:
1.26 markus 332: /* parse buffer and return algorithm proposal */
1.102 markus 333: int
334: kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
1.7 markus 335: {
1.102 markus 336: struct sshbuf *b = NULL;
337: u_char v;
1.78 djm 338: u_int i;
1.102 markus 339: char **proposal = NULL;
340: int r;
1.7 markus 341:
1.102 markus 342: *propp = NULL;
343: if ((proposal = calloc(PROPOSAL_MAX, sizeof(char *))) == NULL)
344: return SSH_ERR_ALLOC_FAIL;
345: if ((b = sshbuf_fromb(raw)) == NULL) {
346: r = SSH_ERR_ALLOC_FAIL;
347: goto out;
348: }
1.152 djm 349: if ((r = sshbuf_consume(b, KEX_COOKIE_LEN)) != 0) { /* skip cookie */
350: error("%s: consume cookie: %s", __func__, ssh_err(r));
1.102 markus 351: goto out;
1.152 djm 352: }
1.7 markus 353: /* extract kex init proposal strings */
354: for (i = 0; i < PROPOSAL_MAX; i++) {
1.152 djm 355: if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0) {
356: error("%s: parse proposal %u: %s", __func__,
357: i, ssh_err(r));
1.102 markus 358: goto out;
1.152 djm 359: }
1.110 djm 360: debug2("%s: %s", proposal_names[i], proposal[i]);
1.7 markus 361: }
1.26 markus 362: /* first kex follows / reserved */
1.115 djm 363: if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
1.152 djm 364: (r = sshbuf_get_u32(b, &i)) != 0) { /* reserved */
365: error("%s: parse: %s", __func__, ssh_err(r));
1.102 markus 366: goto out;
1.152 djm 367: }
1.53 markus 368: if (first_kex_follows != NULL)
1.115 djm 369: *first_kex_follows = v;
1.110 djm 370: debug2("first_kex_follows %d ", v);
371: debug2("reserved %u ", i);
1.102 markus 372: r = 0;
373: *propp = proposal;
374: out:
375: if (r != 0 && proposal != NULL)
376: kex_prop_free(proposal);
377: sshbuf_free(b);
378: return r;
1.1 markus 379: }
380:
1.102 markus 381: void
1.26 markus 382: kex_prop_free(char **proposal)
1.1 markus 383: {
1.61 djm 384: u_int i;
1.26 markus 385:
1.106 djm 386: if (proposal == NULL)
387: return;
1.26 markus 388: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 djm 389: free(proposal[i]);
390: free(proposal);
1.1 markus 391: }
392:
1.78 djm 393: /* ARGSUSED */
1.101 markus 394: static int
1.133 markus 395: kex_protocol_error(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 396: {
1.112 djm 397: int r;
398:
399: error("kex protocol error: type %d seq %u", type, seq);
400: if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
401: (r = sshpkt_put_u32(ssh, seq)) != 0 ||
402: (r = sshpkt_send(ssh)) != 0)
403: return r;
1.101 markus 404: return 0;
1.26 markus 405: }
1.1 markus 406:
1.35 itojun 407: static void
1.102 markus 408: kex_reset_dispatch(struct ssh *ssh)
1.29 markus 409: {
1.102 markus 410: ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
1.42 markus 411: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.29 markus 412: }
413:
1.113 markus 414: static int
415: kex_send_ext_info(struct ssh *ssh)
416: {
417: int r;
1.121 djm 418: char *algs;
1.113 markus 419:
1.151 djm 420: debug("Sending SSH2_MSG_EXT_INFO");
1.130 djm 421: if ((algs = sshkey_alg_list(0, 1, 1, ',')) == NULL)
1.121 djm 422: return SSH_ERR_ALLOC_FAIL;
1.137 djm 423: /* XXX filter algs list by allowed pubkey/hostbased types */
1.113 markus 424: if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
425: (r = sshpkt_put_u32(ssh, 1)) != 0 ||
426: (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 ||
1.121 djm 427: (r = sshpkt_put_cstring(ssh, algs)) != 0 ||
1.152 djm 428: (r = sshpkt_send(ssh)) != 0) {
429: error("%s: compose: %s", __func__, ssh_err(r));
1.121 djm 430: goto out;
1.152 djm 431: }
1.121 djm 432: /* success */
433: r = 0;
434: out:
435: free(algs);
1.123 djm 436: return r;
1.113 markus 437: }
438:
1.102 markus 439: int
440: kex_send_newkeys(struct ssh *ssh)
1.26 markus 441: {
1.102 markus 442: int r;
1.28 markus 443:
1.102 markus 444: kex_reset_dispatch(ssh);
445: if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
446: (r = sshpkt_send(ssh)) != 0)
447: return r;
1.26 markus 448: debug("SSH2_MSG_NEWKEYS sent");
1.102 markus 449: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
1.151 djm 450: if (ssh->kex->ext_info_c && (ssh->kex->flags & KEX_INITIAL) != 0)
1.113 markus 451: if ((r = kex_send_ext_info(ssh)) != 0)
452: return r;
1.151 djm 453: debug("expecting SSH2_MSG_NEWKEYS");
1.102 markus 454: return 0;
455: }
456:
1.113 markus 457: int
1.133 markus 458: kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
1.113 markus 459: {
460: struct kex *kex = ssh->kex;
461: u_int32_t i, ninfo;
1.137 djm 462: char *name;
1.134 djm 463: u_char *val;
464: size_t vlen;
1.113 markus 465: int r;
466:
467: debug("SSH2_MSG_EXT_INFO received");
468: ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
469: if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
470: return r;
471: for (i = 0; i < ninfo; i++) {
472: if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
473: return r;
1.134 djm 474: if ((r = sshpkt_get_string(ssh, &val, &vlen)) != 0) {
1.113 markus 475: free(name);
476: return r;
477: }
478: if (strcmp(name, "server-sig-algs") == 0) {
1.134 djm 479: /* Ensure no \0 lurking in value */
480: if (memchr(val, '\0', vlen) != NULL) {
481: error("%s: nul byte in %s", __func__, name);
482: return SSH_ERR_INVALID_FORMAT;
483: }
484: debug("%s: %s=<%s>", __func__, name, val);
1.137 djm 485: kex->server_sig_algs = val;
486: val = NULL;
1.134 djm 487: } else
488: debug("%s: %s (unrecognised)", __func__, name);
1.113 markus 489: free(name);
490: free(val);
491: }
492: return sshpkt_get_end(ssh);
493: }
494:
1.102 markus 495: static int
1.133 markus 496: kex_input_newkeys(int type, u_int32_t seq, struct ssh *ssh)
1.102 markus 497: {
498: struct kex *kex = ssh->kex;
499: int r;
1.19 stevesk 500:
1.26 markus 501: debug("SSH2_MSG_NEWKEYS received");
1.102 markus 502: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
1.131 markus 503: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.102 markus 504: if ((r = sshpkt_get_end(ssh)) != 0)
1.122 markus 505: return r;
506: if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
1.102 markus 507: return r;
1.30 markus 508: kex->done = 1;
1.142 djm 509: kex->flags &= ~KEX_INITIAL;
1.102 markus 510: sshbuf_reset(kex->peer);
511: /* sshbuf_reset(kex->my); */
1.26 markus 512: kex->flags &= ~KEX_INIT_SENT;
1.91 djm 513: free(kex->name);
1.32 markus 514: kex->name = NULL;
1.102 markus 515: return 0;
1.26 markus 516: }
1.1 markus 517:
1.102 markus 518: int
519: kex_send_kexinit(struct ssh *ssh)
1.26 markus 520: {
1.49 markus 521: u_char *cookie;
1.102 markus 522: struct kex *kex = ssh->kex;
523: int r;
1.49 markus 524:
1.152 djm 525: if (kex == NULL) {
526: error("%s: no hex", __func__);
1.102 markus 527: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 528: }
1.102 markus 529: if (kex->flags & KEX_INIT_SENT)
530: return 0;
1.30 markus 531: kex->done = 0;
1.49 markus 532:
533: /* generate a random cookie */
1.152 djm 534: if (sshbuf_len(kex->my) < KEX_COOKIE_LEN) {
535: error("%s: bad kex length: %zu < %d", __func__,
536: sshbuf_len(kex->my), KEX_COOKIE_LEN);
1.102 markus 537: return SSH_ERR_INVALID_FORMAT;
1.152 djm 538: }
539: if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL) {
540: error("%s: buffer error", __func__);
1.102 markus 541: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 542: }
1.102 markus 543: arc4random_buf(cookie, KEX_COOKIE_LEN);
544:
545: if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
546: (r = sshpkt_putb(ssh, kex->my)) != 0 ||
1.152 djm 547: (r = sshpkt_send(ssh)) != 0) {
548: error("%s: compose reply: %s", __func__, ssh_err(r));
1.102 markus 549: return r;
1.152 djm 550: }
1.26 markus 551: debug("SSH2_MSG_KEXINIT sent");
552: kex->flags |= KEX_INIT_SENT;
1.102 markus 553: return 0;
1.1 markus 554: }
555:
1.78 djm 556: /* ARGSUSED */
1.101 markus 557: int
1.133 markus 558: kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
1.11 provos 559: {
1.102 markus 560: struct kex *kex = ssh->kex;
561: const u_char *ptr;
1.100 markus 562: u_int i;
563: size_t dlen;
1.102 markus 564: int r;
1.11 provos 565:
1.26 markus 566: debug("SSH2_MSG_KEXINIT received");
1.152 djm 567: if (kex == NULL) {
568: error("%s: no hex", __func__);
569: return SSH_ERR_INTERNAL_ERROR;
570: }
1.127 markus 571: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, NULL);
1.102 markus 572: ptr = sshpkt_ptr(ssh, &dlen);
573: if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
574: return r;
1.31 markus 575:
576: /* discard packet */
1.152 djm 577: for (i = 0; i < KEX_COOKIE_LEN; i++) {
578: if ((r = sshpkt_get_u8(ssh, NULL)) != 0) {
579: error("%s: discard cookie: %s", __func__, ssh_err(r));
1.102 markus 580: return r;
1.152 djm 581: }
582: }
583: for (i = 0; i < PROPOSAL_MAX; i++) {
584: if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
585: error("%s: discard proposal: %s", __func__, ssh_err(r));
1.102 markus 586: return r;
1.152 djm 587: }
588: }
1.87 djm 589: /*
590: * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
591: * KEX method has the server move first, but a server might be using
592: * a custom method or one that we otherwise don't support. We should
593: * be prepared to remember first_kex_follows here so we can eat a
594: * packet later.
595: * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
596: * for cases where the server *doesn't* go first. I guess we should
597: * ignore it when it is set for these cases, which is what we do now.
598: */
1.102 markus 599: if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
600: (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
601: (r = sshpkt_get_end(ssh)) != 0)
602: return r;
603:
604: if (!(kex->flags & KEX_INIT_SENT))
605: if ((r = kex_send_kexinit(ssh)) != 0)
606: return r;
607: if ((r = kex_choose_conf(ssh)) != 0)
608: return r;
1.19 stevesk 609:
1.102 markus 610: if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
611: return (kex->kex[kex->kex_type])(ssh);
612:
1.152 djm 613: error("%s: unknown kex type %u", __func__, kex->kex_type);
1.102 markus 614: return SSH_ERR_INTERNAL_ERROR;
615: }
616:
1.143 djm 617: struct kex *
618: kex_new(void)
1.102 markus 619: {
620: struct kex *kex;
621:
1.143 djm 622: if ((kex = calloc(1, sizeof(*kex))) == NULL ||
623: (kex->peer = sshbuf_new()) == NULL ||
624: (kex->my = sshbuf_new()) == NULL ||
625: (kex->client_version = sshbuf_new()) == NULL ||
626: (kex->server_version = sshbuf_new()) == NULL) {
627: kex_free(kex);
628: return NULL;
1.102 markus 629: }
1.143 djm 630: return kex;
1.26 markus 631: }
1.11 provos 632:
1.100 markus 633: void
634: kex_free_newkeys(struct newkeys *newkeys)
635: {
636: if (newkeys == NULL)
637: return;
638: if (newkeys->enc.key) {
639: explicit_bzero(newkeys->enc.key, newkeys->enc.key_len);
640: free(newkeys->enc.key);
641: newkeys->enc.key = NULL;
642: }
643: if (newkeys->enc.iv) {
1.111 djm 644: explicit_bzero(newkeys->enc.iv, newkeys->enc.iv_len);
1.100 markus 645: free(newkeys->enc.iv);
646: newkeys->enc.iv = NULL;
647: }
648: free(newkeys->enc.name);
649: explicit_bzero(&newkeys->enc, sizeof(newkeys->enc));
650: free(newkeys->comp.name);
651: explicit_bzero(&newkeys->comp, sizeof(newkeys->comp));
652: mac_clear(&newkeys->mac);
653: if (newkeys->mac.key) {
654: explicit_bzero(newkeys->mac.key, newkeys->mac.key_len);
655: free(newkeys->mac.key);
656: newkeys->mac.key = NULL;
657: }
658: free(newkeys->mac.name);
659: explicit_bzero(&newkeys->mac, sizeof(newkeys->mac));
1.157 jsg 660: freezero(newkeys, sizeof(*newkeys));
1.100 markus 661: }
662:
1.102 markus 663: void
664: kex_free(struct kex *kex)
1.26 markus 665: {
1.102 markus 666: u_int mode;
1.11 provos 667:
1.143 djm 668: if (kex == NULL)
669: return;
670:
1.102 markus 671: #ifdef WITH_OPENSSL
1.136 jsing 672: DH_free(kex->dh);
673: EC_KEY_free(kex->ec_client_key);
1.102 markus 674: #endif
675: for (mode = 0; mode < MODE_MAX; mode++) {
676: kex_free_newkeys(kex->newkeys[mode]);
677: kex->newkeys[mode] = NULL;
1.100 markus 678: }
1.102 markus 679: sshbuf_free(kex->peer);
680: sshbuf_free(kex->my);
1.143 djm 681: sshbuf_free(kex->client_version);
682: sshbuf_free(kex->server_version);
1.149 djm 683: sshbuf_free(kex->client_pub);
1.102 markus 684: free(kex->session_id);
1.107 djm 685: free(kex->failed_choice);
1.113 markus 686: free(kex->hostkey_alg);
687: free(kex->name);
1.102 markus 688: free(kex);
1.11 provos 689: }
690:
1.102 markus 691: int
1.143 djm 692: kex_ready(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
693: {
694: int r;
695:
696: if ((r = kex_prop2buf(ssh->kex->my, proposal)) != 0)
697: return r;
698: ssh->kex->flags = KEX_INITIAL;
699: kex_reset_dispatch(ssh);
700: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
701: return 0;
702: }
703:
704: int
1.102 markus 705: kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
1.1 markus 706: {
1.102 markus 707: int r;
1.1 markus 708:
1.143 djm 709: if ((r = kex_ready(ssh, proposal)) != 0)
1.102 markus 710: return r;
711: if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
712: kex_free(ssh->kex);
713: ssh->kex = NULL;
714: return r;
1.1 markus 715: }
1.102 markus 716: return 0;
1.117 djm 717: }
718:
719: /*
720: * Request key re-exchange, returns 0 on success or a ssherr.h error
721: * code otherwise. Must not be called if KEX is incomplete or in-progress.
722: */
723: int
724: kex_start_rekex(struct ssh *ssh)
725: {
726: if (ssh->kex == NULL) {
727: error("%s: no kex", __func__);
728: return SSH_ERR_INTERNAL_ERROR;
729: }
730: if (ssh->kex->done == 0) {
731: error("%s: requested twice", __func__);
732: return SSH_ERR_INTERNAL_ERROR;
733: }
734: ssh->kex->done = 0;
735: return kex_send_kexinit(ssh);
1.1 markus 736: }
737:
1.102 markus 738: static int
739: choose_enc(struct sshenc *enc, char *client, char *server)
1.1 markus 740: {
1.23 markus 741: char *name = match_list(client, server, NULL);
1.102 markus 742:
1.1 markus 743: if (name == NULL)
1.102 markus 744: return SSH_ERR_NO_CIPHER_ALG_MATCH;
1.129 dtucker 745: if ((enc->cipher = cipher_by_name(name)) == NULL) {
1.152 djm 746: error("%s: unsupported cipher %s", __func__, name);
1.129 dtucker 747: free(name);
1.102 markus 748: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 749: }
1.1 markus 750: enc->name = name;
751: enc->enabled = 0;
752: enc->iv = NULL;
1.88 markus 753: enc->iv_len = cipher_ivlen(enc->cipher);
1.1 markus 754: enc->key = NULL;
1.45 markus 755: enc->key_len = cipher_keylen(enc->cipher);
756: enc->block_size = cipher_blocksize(enc->cipher);
1.102 markus 757: return 0;
1.1 markus 758: }
1.69 deraadt 759:
1.102 markus 760: static int
761: choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
1.1 markus 762: {
1.23 markus 763: char *name = match_list(client, server, NULL);
1.102 markus 764:
1.1 markus 765: if (name == NULL)
1.102 markus 766: return SSH_ERR_NO_MAC_ALG_MATCH;
1.129 dtucker 767: if (mac_setup(mac, name) < 0) {
1.152 djm 768: error("%s: unsupported MAC %s", __func__, name);
1.129 dtucker 769: free(name);
1.102 markus 770: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 771: }
1.1 markus 772: mac->name = name;
773: mac->key = NULL;
774: mac->enabled = 0;
1.102 markus 775: return 0;
1.1 markus 776: }
1.69 deraadt 777:
1.102 markus 778: static int
779: choose_comp(struct sshcomp *comp, char *client, char *server)
1.1 markus 780: {
1.23 markus 781: char *name = match_list(client, server, NULL);
1.102 markus 782:
1.1 markus 783: if (name == NULL)
1.102 markus 784: return SSH_ERR_NO_COMPRESS_ALG_MATCH;
1.156 dtucker 785: #ifdef WITH_ZLIB
1.64 markus 786: if (strcmp(name, "zlib@openssh.com") == 0) {
1.141 sf 787: comp->type = COMP_DELAYED;
788: } else if (strcmp(name, "zlib") == 0) {
1.140 sf 789: comp->type = COMP_ZLIB;
1.156 dtucker 790: } else
791: #endif /* WITH_ZLIB */
792: if (strcmp(name, "none") == 0) {
1.64 markus 793: comp->type = COMP_NONE;
1.1 markus 794: } else {
1.152 djm 795: error("%s: unsupported compression scheme %s", __func__, name);
1.129 dtucker 796: free(name);
1.102 markus 797: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 798: }
799: comp->name = name;
1.102 markus 800: return 0;
1.1 markus 801: }
1.69 deraadt 802:
1.102 markus 803: static int
804: choose_kex(struct kex *k, char *client, char *server)
1.1 markus 805: {
1.89 djm 806: const struct kexalg *kexalg;
807:
1.23 markus 808: k->name = match_list(client, server, NULL);
1.102 markus 809:
1.110 djm 810: debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
1.1 markus 811: if (k->name == NULL)
1.102 markus 812: return SSH_ERR_NO_KEX_ALG_MATCH;
1.152 djm 813: if ((kexalg = kex_alg_by_name(k->name)) == NULL) {
814: error("%s: unsupported KEX method %s", __func__, k->name);
1.102 markus 815: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 816: }
1.89 djm 817: k->kex_type = kexalg->type;
1.94 djm 818: k->hash_alg = kexalg->hash_alg;
1.89 djm 819: k->ec_nid = kexalg->ec_nid;
1.102 markus 820: return 0;
1.1 markus 821: }
1.65 djm 822:
1.102 markus 823: static int
824: choose_hostkeyalg(struct kex *k, char *client, char *server)
1.1 markus 825: {
1.113 markus 826: k->hostkey_alg = match_list(client, server, NULL);
1.102 markus 827:
1.110 djm 828: debug("kex: host key algorithm: %s",
1.113 markus 829: k->hostkey_alg ? k->hostkey_alg : "(no match)");
830: if (k->hostkey_alg == NULL)
1.102 markus 831: return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
1.113 markus 832: k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
1.152 djm 833: if (k->hostkey_type == KEY_UNSPEC) {
834: error("%s: unsupported hostkey algorithm %s", __func__,
835: k->hostkey_alg);
1.102 markus 836: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 837: }
1.113 markus 838: k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
1.102 markus 839: return 0;
1.1 markus 840: }
841:
1.56 djm 842: static int
1.53 markus 843: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
844: {
845: static int check[] = {
846: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
847: };
848: int *idx;
849: char *p;
850:
851: for (idx = &check[0]; *idx != -1; idx++) {
852: if ((p = strchr(my[*idx], ',')) != NULL)
853: *p = '\0';
854: if ((p = strchr(peer[*idx], ',')) != NULL)
855: *p = '\0';
856: if (strcmp(my[*idx], peer[*idx]) != 0) {
857: debug2("proposal mismatch: my %s peer %s",
858: my[*idx], peer[*idx]);
859: return (0);
860: }
861: }
862: debug2("proposals match");
863: return (1);
864: }
865:
1.102 markus 866: static int
867: kex_choose_conf(struct ssh *ssh)
1.1 markus 868: {
1.102 markus 869: struct kex *kex = ssh->kex;
870: struct newkeys *newkeys;
871: char **my = NULL, **peer = NULL;
1.26 markus 872: char **cprop, **sprop;
1.27 markus 873: int nenc, nmac, ncomp;
1.96 dtucker 874: u_int mode, ctos, need, dh_need, authlen;
1.102 markus 875: int r, first_kex_follows;
1.1 markus 876:
1.110 djm 877: debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
878: if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
879: goto out;
880: debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
881: if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
1.102 markus 882: goto out;
1.26 markus 883:
1.27 markus 884: if (kex->server) {
1.26 markus 885: cprop=peer;
886: sprop=my;
887: } else {
888: cprop=my;
889: sprop=peer;
1.113 markus 890: }
891:
892: /* Check whether client supports ext_info_c */
1.142 djm 893: if (kex->server && (kex->flags & KEX_INITIAL)) {
1.113 markus 894: char *ext;
895:
896: ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
1.119 markus 897: kex->ext_info_c = (ext != NULL);
898: free(ext);
1.26 markus 899: }
1.1 markus 900:
1.30 markus 901: /* Algorithm Negotiation */
1.110 djm 902: if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
903: sprop[PROPOSAL_KEX_ALGS])) != 0) {
904: kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
905: peer[PROPOSAL_KEX_ALGS] = NULL;
906: goto out;
907: }
908: if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
909: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
910: kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
911: peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
912: goto out;
913: }
1.1 markus 914: for (mode = 0; mode < MODE_MAX; mode++) {
1.102 markus 915: if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
916: r = SSH_ERR_ALLOC_FAIL;
917: goto out;
918: }
1.30 markus 919: kex->newkeys[mode] = newkeys;
1.78 djm 920: ctos = (!kex->server && mode == MODE_OUT) ||
921: (kex->server && mode == MODE_IN);
1.1 markus 922: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
923: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
924: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.102 markus 925: if ((r = choose_enc(&newkeys->enc, cprop[nenc],
1.107 djm 926: sprop[nenc])) != 0) {
927: kex->failed_choice = peer[nenc];
928: peer[nenc] = NULL;
1.102 markus 929: goto out;
1.107 djm 930: }
1.102 markus 931: authlen = cipher_authlen(newkeys->enc.cipher);
1.88 markus 932: /* ignore mac for authenticated encryption */
1.102 markus 933: if (authlen == 0 &&
934: (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
1.107 djm 935: sprop[nmac])) != 0) {
936: kex->failed_choice = peer[nmac];
937: peer[nmac] = NULL;
1.102 markus 938: goto out;
1.107 djm 939: }
1.102 markus 940: if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
1.107 djm 941: sprop[ncomp])) != 0) {
942: kex->failed_choice = peer[ncomp];
943: peer[ncomp] = NULL;
1.102 markus 944: goto out;
1.107 djm 945: }
1.110 djm 946: debug("kex: %s cipher: %s MAC: %s compression: %s",
1.1 markus 947: ctos ? "client->server" : "server->client",
1.27 markus 948: newkeys->enc.name,
1.88 markus 949: authlen == 0 ? newkeys->mac.name : "<implicit>",
1.27 markus 950: newkeys->comp.name);
1.107 djm 951: }
1.96 dtucker 952: need = dh_need = 0;
1.1 markus 953: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 954: newkeys = kex->newkeys[mode];
1.120 deraadt 955: need = MAXIMUM(need, newkeys->enc.key_len);
956: need = MAXIMUM(need, newkeys->enc.block_size);
957: need = MAXIMUM(need, newkeys->enc.iv_len);
958: need = MAXIMUM(need, newkeys->mac.key_len);
959: dh_need = MAXIMUM(dh_need, cipher_seclen(newkeys->enc.cipher));
960: dh_need = MAXIMUM(dh_need, newkeys->enc.block_size);
961: dh_need = MAXIMUM(dh_need, newkeys->enc.iv_len);
962: dh_need = MAXIMUM(dh_need, newkeys->mac.key_len);
1.1 markus 963: }
1.7 markus 964: /* XXX need runden? */
1.27 markus 965: kex->we_need = need;
1.96 dtucker 966: kex->dh_need = dh_need;
1.53 markus 967:
968: /* ignore the next message if the proposals do not match */
1.135 djm 969: if (first_kex_follows && !proposals_match(my, peer))
1.102 markus 970: ssh->dispatch_skip_packets = 1;
971: r = 0;
972: out:
1.26 markus 973: kex_prop_free(my);
974: kex_prop_free(peer);
1.102 markus 975: return r;
1.26 markus 976: }
977:
1.102 markus 978: static int
979: derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
980: const struct sshbuf *shared_secret, u_char **keyp)
1.26 markus 981: {
1.102 markus 982: struct kex *kex = ssh->kex;
983: struct ssh_digest_ctx *hashctx = NULL;
1.26 markus 984: char c = id;
1.61 djm 985: u_int have;
1.94 djm 986: size_t mdsz;
1.61 djm 987: u_char *digest;
1.102 markus 988: int r;
1.62 djm 989:
1.94 djm 990: if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
1.102 markus 991: return SSH_ERR_INVALID_ARGUMENT;
1.120 deraadt 992: if ((digest = calloc(1, ROUNDUP(need, mdsz))) == NULL) {
1.102 markus 993: r = SSH_ERR_ALLOC_FAIL;
994: goto out;
995: }
1.26 markus 996:
1.30 markus 997: /* K1 = HASH(K || H || "A" || session_id) */
1.102 markus 998: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
999: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 1000: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1001: ssh_digest_update(hashctx, &c, 1) != 0 ||
1002: ssh_digest_update(hashctx, kex->session_id,
1.102 markus 1003: kex->session_id_len) != 0 ||
1004: ssh_digest_final(hashctx, digest, mdsz) != 0) {
1005: r = SSH_ERR_LIBCRYPTO_ERROR;
1.152 djm 1006: error("%s: KEX hash failed", __func__);
1.102 markus 1007: goto out;
1008: }
1.94 djm 1009: ssh_digest_free(hashctx);
1.102 markus 1010: hashctx = NULL;
1.26 markus 1011:
1.30 markus 1012: /*
1013: * expand key:
1014: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
1015: * Key = K1 || K2 || ... || Kn
1016: */
1.26 markus 1017: for (have = mdsz; need > have; have += mdsz) {
1.102 markus 1018: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1019: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 1020: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1.102 markus 1021: ssh_digest_update(hashctx, digest, have) != 0 ||
1022: ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
1.152 djm 1023: error("%s: KDF failed", __func__);
1.102 markus 1024: r = SSH_ERR_LIBCRYPTO_ERROR;
1025: goto out;
1026: }
1.94 djm 1027: ssh_digest_free(hashctx);
1.102 markus 1028: hashctx = NULL;
1.26 markus 1029: }
1030: #ifdef DEBUG_KEX
1031: fprintf(stderr, "key '%c'== ", c);
1032: dump_digest("key", digest, need);
1033: #endif
1.102 markus 1034: *keyp = digest;
1035: digest = NULL;
1036: r = 0;
1037: out:
1.114 mmcc 1038: free(digest);
1.102 markus 1039: ssh_digest_free(hashctx);
1040: return r;
1.1 markus 1041: }
1042:
1.23 markus 1043: #define NKEYS 6
1.102 markus 1044: int
1045: kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
1046: const struct sshbuf *shared_secret)
1.1 markus 1047: {
1.102 markus 1048: struct kex *kex = ssh->kex;
1.15 markus 1049: u_char *keys[NKEYS];
1.102 markus 1050: u_int i, j, mode, ctos;
1051: int r;
1.1 markus 1052:
1.144 djm 1053: /* save initial hash as session id */
1054: if (kex->session_id == NULL) {
1055: kex->session_id_len = hashlen;
1056: kex->session_id = malloc(kex->session_id_len);
1057: if (kex->session_id == NULL)
1058: return SSH_ERR_ALLOC_FAIL;
1059: memcpy(kex->session_id, hash, kex->session_id_len);
1060: }
1.65 djm 1061: for (i = 0; i < NKEYS; i++) {
1.102 markus 1062: if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
1063: shared_secret, &keys[i])) != 0) {
1064: for (j = 0; j < i; j++)
1065: free(keys[j]);
1066: return r;
1067: }
1.65 djm 1068: }
1.1 markus 1069: for (mode = 0; mode < MODE_MAX; mode++) {
1.69 deraadt 1070: ctos = (!kex->server && mode == MODE_OUT) ||
1071: (kex->server && mode == MODE_IN);
1.100 markus 1072: kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
1073: kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
1074: kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 1075: }
1.102 markus 1076: return 0;
1.95 djm 1077: }
1.57 djm 1078:
1.145 djm 1079: int
1.150 djm 1080: kex_load_hostkey(struct ssh *ssh, struct sshkey **prvp, struct sshkey **pubp)
1.145 djm 1081: {
1082: struct kex *kex = ssh->kex;
1083:
1084: *pubp = NULL;
1085: *prvp = NULL;
1086: if (kex->load_host_public_key == NULL ||
1.152 djm 1087: kex->load_host_private_key == NULL) {
1088: error("%s: missing hostkey loader", __func__);
1.145 djm 1089: return SSH_ERR_INVALID_ARGUMENT;
1.152 djm 1090: }
1.145 djm 1091: *pubp = kex->load_host_public_key(kex->hostkey_type,
1092: kex->hostkey_nid, ssh);
1093: *prvp = kex->load_host_private_key(kex->hostkey_type,
1094: kex->hostkey_nid, ssh);
1095: if (*pubp == NULL)
1096: return SSH_ERR_NO_HOSTKEY_LOADED;
1.146 djm 1097: return 0;
1098: }
1099:
1100: int
1101: kex_verify_host_key(struct ssh *ssh, struct sshkey *server_host_key)
1102: {
1103: struct kex *kex = ssh->kex;
1104:
1.152 djm 1105: if (kex->verify_host_key == NULL) {
1106: error("%s: missing hostkey verifier", __func__);
1.146 djm 1107: return SSH_ERR_INVALID_ARGUMENT;
1.152 djm 1108: }
1.146 djm 1109: if (server_host_key->type != kex->hostkey_type ||
1110: (kex->hostkey_type == KEY_ECDSA &&
1111: server_host_key->ecdsa_nid != kex->hostkey_nid))
1112: return SSH_ERR_KEY_TYPE_MISMATCH;
1113: if (kex->verify_host_key(server_host_key, ssh) == -1)
1114: return SSH_ERR_SIGNATURE_INVALID;
1.145 djm 1115: return 0;
1116: }
1.26 markus 1117:
1.84 djm 1118: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1.26 markus 1119: void
1.147 djm 1120: dump_digest(const char *msg, const u_char *digest, int len)
1.26 markus 1121: {
1122: fprintf(stderr, "%s\n", msg);
1.102 markus 1123: sshbuf_dump_data(digest, len, stderr);
1.26 markus 1124: }
1125: #endif
1.143 djm 1126:
1127: /*
1128: * Send a plaintext error message to the peer, suffixed by \r\n.
1129: * Only used during banner exchange, and there only for the server.
1130: */
1131: static void
1132: send_error(struct ssh *ssh, char *msg)
1133: {
1134: char *crnl = "\r\n";
1135:
1136: if (!ssh->kex->server)
1137: return;
1138:
1139: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1140: msg, strlen(msg)) != strlen(msg) ||
1141: atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1142: crnl, strlen(crnl)) != strlen(crnl))
1143: error("%s: write: %.100s", __func__, strerror(errno));
1144: }
1145:
1146: /*
1147: * Sends our identification string and waits for the peer's. Will block for
1148: * up to timeout_ms (or indefinitely if timeout_ms <= 0).
1149: * Returns on 0 success or a ssherr.h code on failure.
1150: */
1151: int
1152: kex_exchange_identification(struct ssh *ssh, int timeout_ms,
1153: const char *version_addendum)
1154: {
1.158 ! djm 1155: int remote_major, remote_minor, mismatch, oerrno = 0;
1.143 djm 1156: size_t len, i, n;
1157: int r, expect_nl;
1158: u_char c;
1159: struct sshbuf *our_version = ssh->kex->server ?
1160: ssh->kex->server_version : ssh->kex->client_version;
1161: struct sshbuf *peer_version = ssh->kex->server ?
1162: ssh->kex->client_version : ssh->kex->server_version;
1163: char *our_version_string = NULL, *peer_version_string = NULL;
1164: char *cp, *remote_version = NULL;
1165:
1166: /* Prepare and send our banner */
1167: sshbuf_reset(our_version);
1168: if (version_addendum != NULL && *version_addendum == '\0')
1169: version_addendum = NULL;
1170: if ((r = sshbuf_putf(our_version, "SSH-%d.%d-%.100s%s%s\r\n",
1171: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
1172: version_addendum == NULL ? "" : " ",
1173: version_addendum == NULL ? "" : version_addendum)) != 0) {
1.158 ! djm 1174: oerrno = errno;
1.143 djm 1175: error("%s: sshbuf_putf: %s", __func__, ssh_err(r));
1176: goto out;
1177: }
1178:
1179: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1180: sshbuf_mutable_ptr(our_version),
1181: sshbuf_len(our_version)) != sshbuf_len(our_version)) {
1.158 ! djm 1182: oerrno = errno;
! 1183: debug("%s: write: %.100s", __func__, strerror(errno));
1.143 djm 1184: r = SSH_ERR_SYSTEM_ERROR;
1185: goto out;
1186: }
1187: if ((r = sshbuf_consume_end(our_version, 2)) != 0) { /* trim \r\n */
1.158 ! djm 1188: oerrno = errno;
1.143 djm 1189: error("%s: sshbuf_consume_end: %s", __func__, ssh_err(r));
1190: goto out;
1191: }
1192: our_version_string = sshbuf_dup_string(our_version);
1193: if (our_version_string == NULL) {
1194: error("%s: sshbuf_dup_string failed", __func__);
1195: r = SSH_ERR_ALLOC_FAIL;
1196: goto out;
1197: }
1198: debug("Local version string %.100s", our_version_string);
1199:
1200: /* Read other side's version identification. */
1201: for (n = 0; ; n++) {
1202: if (n >= SSH_MAX_PRE_BANNER_LINES) {
1203: send_error(ssh, "No SSH identification string "
1204: "received.");
1205: error("%s: No SSH version received in first %u lines "
1206: "from server", __func__, SSH_MAX_PRE_BANNER_LINES);
1207: r = SSH_ERR_INVALID_FORMAT;
1208: goto out;
1209: }
1210: sshbuf_reset(peer_version);
1211: expect_nl = 0;
1212: for (i = 0; ; i++) {
1213: if (timeout_ms > 0) {
1214: r = waitrfd(ssh_packet_get_connection_in(ssh),
1215: &timeout_ms);
1216: if (r == -1 && errno == ETIMEDOUT) {
1217: send_error(ssh, "Timed out waiting "
1218: "for SSH identification string.");
1219: error("Connection timed out during "
1220: "banner exchange");
1221: r = SSH_ERR_CONN_TIMEOUT;
1222: goto out;
1223: } else if (r == -1) {
1.158 ! djm 1224: oerrno = errno;
1.143 djm 1225: error("%s: %s",
1226: __func__, strerror(errno));
1227: r = SSH_ERR_SYSTEM_ERROR;
1228: goto out;
1229: }
1230: }
1231:
1232: len = atomicio(read, ssh_packet_get_connection_in(ssh),
1233: &c, 1);
1234: if (len != 1 && errno == EPIPE) {
1235: error("%s: Connection closed by remote host",
1236: __func__);
1237: r = SSH_ERR_CONN_CLOSED;
1238: goto out;
1239: } else if (len != 1) {
1.158 ! djm 1240: oerrno = errno;
1.143 djm 1241: error("%s: read: %.100s",
1242: __func__, strerror(errno));
1243: r = SSH_ERR_SYSTEM_ERROR;
1244: goto out;
1245: }
1246: if (c == '\r') {
1247: expect_nl = 1;
1248: continue;
1249: }
1250: if (c == '\n')
1251: break;
1252: if (c == '\0' || expect_nl) {
1253: error("%s: banner line contains invalid "
1254: "characters", __func__);
1255: goto invalid;
1256: }
1257: if ((r = sshbuf_put_u8(peer_version, c)) != 0) {
1.158 ! djm 1258: oerrno = errno;
1.143 djm 1259: error("%s: sshbuf_put: %s",
1260: __func__, ssh_err(r));
1261: goto out;
1262: }
1263: if (sshbuf_len(peer_version) > SSH_MAX_BANNER_LEN) {
1264: error("%s: banner line too long", __func__);
1265: goto invalid;
1266: }
1267: }
1268: /* Is this an actual protocol banner? */
1269: if (sshbuf_len(peer_version) > 4 &&
1270: memcmp(sshbuf_ptr(peer_version), "SSH-", 4) == 0)
1271: break;
1272: /* If not, then just log the line and continue */
1273: if ((cp = sshbuf_dup_string(peer_version)) == NULL) {
1274: error("%s: sshbuf_dup_string failed", __func__);
1275: r = SSH_ERR_ALLOC_FAIL;
1276: goto out;
1277: }
1278: /* Do not accept lines before the SSH ident from a client */
1279: if (ssh->kex->server) {
1280: error("%s: client sent invalid protocol identifier "
1281: "\"%.256s\"", __func__, cp);
1282: free(cp);
1283: goto invalid;
1284: }
1285: debug("%s: banner line %zu: %s", __func__, n, cp);
1286: free(cp);
1287: }
1288: peer_version_string = sshbuf_dup_string(peer_version);
1289: if (peer_version_string == NULL)
1290: error("%s: sshbuf_dup_string failed", __func__);
1291: /* XXX must be same size for sscanf */
1292: if ((remote_version = calloc(1, sshbuf_len(peer_version))) == NULL) {
1293: error("%s: calloc failed", __func__);
1294: r = SSH_ERR_ALLOC_FAIL;
1295: goto out;
1296: }
1297:
1298: /*
1299: * Check that the versions match. In future this might accept
1300: * several versions and set appropriate flags to handle them.
1301: */
1302: if (sscanf(peer_version_string, "SSH-%d.%d-%[^\n]\n",
1303: &remote_major, &remote_minor, remote_version) != 3) {
1304: error("Bad remote protocol version identification: '%.100s'",
1305: peer_version_string);
1306: invalid:
1307: send_error(ssh, "Invalid SSH identification string.");
1308: r = SSH_ERR_INVALID_FORMAT;
1309: goto out;
1310: }
1311: debug("Remote protocol version %d.%d, remote software version %.100s",
1312: remote_major, remote_minor, remote_version);
1313: ssh->compat = compat_datafellows(remote_version);
1314:
1315: mismatch = 0;
1316: switch (remote_major) {
1317: case 2:
1318: break;
1319: case 1:
1320: if (remote_minor != 99)
1321: mismatch = 1;
1322: break;
1323: default:
1324: mismatch = 1;
1325: break;
1326: }
1327: if (mismatch) {
1328: error("Protocol major versions differ: %d vs. %d",
1329: PROTOCOL_MAJOR_2, remote_major);
1330: send_error(ssh, "Protocol major versions differ.");
1331: r = SSH_ERR_NO_PROTOCOL_VERSION;
1332: goto out;
1333: }
1334:
1335: if (ssh->kex->server && (ssh->compat & SSH_BUG_PROBE) != 0) {
1336: logit("probed from %s port %d with %s. Don't panic.",
1337: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1338: peer_version_string);
1339: r = SSH_ERR_CONN_CLOSED; /* XXX */
1340: goto out;
1341: }
1342: if (ssh->kex->server && (ssh->compat & SSH_BUG_SCANNER) != 0) {
1343: logit("scanned from %s port %d with %s. Don't panic.",
1344: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1345: peer_version_string);
1346: r = SSH_ERR_CONN_CLOSED; /* XXX */
1347: goto out;
1348: }
1349: if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
1350: logit("Remote version \"%.100s\" uses unsafe RSA signature "
1351: "scheme; disabling use of RSA keys", remote_version);
1352: }
1353: /* success */
1354: r = 0;
1355: out:
1356: free(our_version_string);
1357: free(peer_version_string);
1358: free(remote_version);
1.158 ! djm 1359: if (r == SSH_ERR_SYSTEM_ERROR)
! 1360: errno = oerrno;
1.143 djm 1361: return r;
1362: }
1363:
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