Annotation of src/usr.bin/ssh/kex.c, Revision 1.169
1.169 ! djm 1: /* $OpenBSD: kex.c,v 1.168 2021/04/03 06:18:40 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 },
1.163 djm 101: { KEX_SNTRUP761X25519_SHA512, KEX_KEM_SNTRUP761X25519_SHA512, 0,
1.147 djm 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 */
1.159 djm 237: if ((*listp = match_filter_denylist(def, list + 1)) == NULL) {
1.138 djm 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);
1.159 djm 274: if ((matching = match_filter_allowlist(all, cp)) == NULL) {
1.138 djm 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 */
1.160 djm 350: error_fr(r, "consume cookie");
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) {
1.160 djm 356: error_fr(r, "parse proposal %u", i);
1.102 markus 357: goto out;
1.152 djm 358: }
1.110 djm 359: debug2("%s: %s", proposal_names[i], proposal[i]);
1.7 markus 360: }
1.26 markus 361: /* first kex follows / reserved */
1.115 djm 362: if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
1.152 djm 363: (r = sshbuf_get_u32(b, &i)) != 0) { /* reserved */
1.160 djm 364: error_fr(r, "parse");
1.102 markus 365: goto out;
1.152 djm 366: }
1.53 markus 367: if (first_kex_follows != NULL)
1.115 djm 368: *first_kex_follows = v;
1.110 djm 369: debug2("first_kex_follows %d ", v);
370: debug2("reserved %u ", i);
1.102 markus 371: r = 0;
372: *propp = proposal;
373: out:
374: if (r != 0 && proposal != NULL)
375: kex_prop_free(proposal);
376: sshbuf_free(b);
377: return r;
1.1 markus 378: }
379:
1.102 markus 380: void
1.26 markus 381: kex_prop_free(char **proposal)
1.1 markus 382: {
1.61 djm 383: u_int i;
1.26 markus 384:
1.106 djm 385: if (proposal == NULL)
386: return;
1.26 markus 387: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 djm 388: free(proposal[i]);
389: free(proposal);
1.1 markus 390: }
391:
1.78 djm 392: /* ARGSUSED */
1.167 djm 393: int
1.133 markus 394: kex_protocol_error(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 395: {
1.112 djm 396: int r;
397:
398: error("kex protocol error: type %d seq %u", type, seq);
399: if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
400: (r = sshpkt_put_u32(ssh, seq)) != 0 ||
401: (r = sshpkt_send(ssh)) != 0)
402: return r;
1.101 markus 403: return 0;
1.26 markus 404: }
1.1 markus 405:
1.35 itojun 406: static void
1.102 markus 407: kex_reset_dispatch(struct ssh *ssh)
1.29 markus 408: {
1.102 markus 409: ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
1.42 markus 410: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.29 markus 411: }
412:
1.113 markus 413: static int
414: kex_send_ext_info(struct ssh *ssh)
415: {
416: int r;
1.121 djm 417: char *algs;
1.113 markus 418:
1.151 djm 419: debug("Sending SSH2_MSG_EXT_INFO");
1.130 djm 420: if ((algs = sshkey_alg_list(0, 1, 1, ',')) == NULL)
1.121 djm 421: return SSH_ERR_ALLOC_FAIL;
1.137 djm 422: /* XXX filter algs list by allowed pubkey/hostbased types */
1.113 markus 423: if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
424: (r = sshpkt_put_u32(ssh, 1)) != 0 ||
425: (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 ||
1.121 djm 426: (r = sshpkt_put_cstring(ssh, algs)) != 0 ||
1.152 djm 427: (r = sshpkt_send(ssh)) != 0) {
1.160 djm 428: error_fr(r, "compose");
1.121 djm 429: goto out;
1.152 djm 430: }
1.121 djm 431: /* success */
432: r = 0;
433: out:
434: free(algs);
1.123 djm 435: return r;
1.113 markus 436: }
437:
1.102 markus 438: int
439: kex_send_newkeys(struct ssh *ssh)
1.26 markus 440: {
1.102 markus 441: int r;
1.28 markus 442:
1.102 markus 443: kex_reset_dispatch(ssh);
444: if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
445: (r = sshpkt_send(ssh)) != 0)
446: return r;
1.26 markus 447: debug("SSH2_MSG_NEWKEYS sent");
1.102 markus 448: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
1.151 djm 449: if (ssh->kex->ext_info_c && (ssh->kex->flags & KEX_INITIAL) != 0)
1.113 markus 450: if ((r = kex_send_ext_info(ssh)) != 0)
451: return r;
1.151 djm 452: debug("expecting SSH2_MSG_NEWKEYS");
1.102 markus 453: return 0;
454: }
455:
1.113 markus 456: int
1.133 markus 457: kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
1.113 markus 458: {
459: struct kex *kex = ssh->kex;
460: u_int32_t i, ninfo;
1.137 djm 461: char *name;
1.134 djm 462: u_char *val;
463: size_t vlen;
1.113 markus 464: int r;
465:
466: debug("SSH2_MSG_EXT_INFO received");
467: ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
468: if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
469: return r;
470: for (i = 0; i < ninfo; i++) {
471: if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
472: return r;
1.134 djm 473: if ((r = sshpkt_get_string(ssh, &val, &vlen)) != 0) {
1.113 markus 474: free(name);
475: return r;
476: }
477: if (strcmp(name, "server-sig-algs") == 0) {
1.134 djm 478: /* Ensure no \0 lurking in value */
479: if (memchr(val, '\0', vlen) != NULL) {
1.160 djm 480: error_f("nul byte in %s", name);
1.134 djm 481: return SSH_ERR_INVALID_FORMAT;
482: }
1.160 djm 483: debug_f("%s=<%s>", name, val);
1.137 djm 484: kex->server_sig_algs = val;
485: val = NULL;
1.134 djm 486: } else
1.160 djm 487: debug_f("%s (unrecognised)", name);
1.113 markus 488: free(name);
489: free(val);
490: }
491: return sshpkt_get_end(ssh);
492: }
493:
1.102 markus 494: static int
1.133 markus 495: kex_input_newkeys(int type, u_int32_t seq, struct ssh *ssh)
1.102 markus 496: {
497: struct kex *kex = ssh->kex;
498: int r;
1.19 stevesk 499:
1.26 markus 500: debug("SSH2_MSG_NEWKEYS received");
1.102 markus 501: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
1.131 markus 502: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.102 markus 503: if ((r = sshpkt_get_end(ssh)) != 0)
1.122 markus 504: return r;
505: if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
1.102 markus 506: return r;
1.30 markus 507: kex->done = 1;
1.142 djm 508: kex->flags &= ~KEX_INITIAL;
1.102 markus 509: sshbuf_reset(kex->peer);
510: /* sshbuf_reset(kex->my); */
1.26 markus 511: kex->flags &= ~KEX_INIT_SENT;
1.91 djm 512: free(kex->name);
1.32 markus 513: kex->name = NULL;
1.102 markus 514: return 0;
1.26 markus 515: }
1.1 markus 516:
1.102 markus 517: int
518: kex_send_kexinit(struct ssh *ssh)
1.26 markus 519: {
1.49 markus 520: u_char *cookie;
1.102 markus 521: struct kex *kex = ssh->kex;
522: int r;
1.49 markus 523:
1.152 djm 524: if (kex == NULL) {
1.161 djm 525: error_f("no kex");
1.102 markus 526: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 527: }
1.102 markus 528: if (kex->flags & KEX_INIT_SENT)
529: return 0;
1.30 markus 530: kex->done = 0;
1.49 markus 531:
532: /* generate a random cookie */
1.152 djm 533: if (sshbuf_len(kex->my) < KEX_COOKIE_LEN) {
1.160 djm 534: error_f("bad kex length: %zu < %d",
1.152 djm 535: sshbuf_len(kex->my), KEX_COOKIE_LEN);
1.102 markus 536: return SSH_ERR_INVALID_FORMAT;
1.152 djm 537: }
538: if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL) {
1.160 djm 539: error_f("buffer error");
1.102 markus 540: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 541: }
1.102 markus 542: arc4random_buf(cookie, KEX_COOKIE_LEN);
543:
544: if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
545: (r = sshpkt_putb(ssh, kex->my)) != 0 ||
1.152 djm 546: (r = sshpkt_send(ssh)) != 0) {
1.160 djm 547: error_fr(r, "compose reply");
1.102 markus 548: return r;
1.152 djm 549: }
1.26 markus 550: debug("SSH2_MSG_KEXINIT sent");
551: kex->flags |= KEX_INIT_SENT;
1.102 markus 552: return 0;
1.1 markus 553: }
554:
1.78 djm 555: /* ARGSUSED */
1.101 markus 556: int
1.133 markus 557: kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
1.11 provos 558: {
1.102 markus 559: struct kex *kex = ssh->kex;
560: const u_char *ptr;
1.100 markus 561: u_int i;
562: size_t dlen;
1.102 markus 563: int r;
1.11 provos 564:
1.26 markus 565: debug("SSH2_MSG_KEXINIT received");
1.152 djm 566: if (kex == NULL) {
1.161 djm 567: error_f("no kex");
1.152 djm 568: return SSH_ERR_INTERNAL_ERROR;
569: }
1.127 markus 570: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, NULL);
1.102 markus 571: ptr = sshpkt_ptr(ssh, &dlen);
572: if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
573: return r;
1.31 markus 574:
575: /* discard packet */
1.152 djm 576: for (i = 0; i < KEX_COOKIE_LEN; i++) {
577: if ((r = sshpkt_get_u8(ssh, NULL)) != 0) {
1.160 djm 578: error_fr(r, "discard cookie");
1.102 markus 579: return r;
1.152 djm 580: }
581: }
582: for (i = 0; i < PROPOSAL_MAX; i++) {
583: if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
1.160 djm 584: error_fr(r, "discard proposal");
1.102 markus 585: return r;
1.152 djm 586: }
587: }
1.87 djm 588: /*
589: * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
590: * KEX method has the server move first, but a server might be using
591: * a custom method or one that we otherwise don't support. We should
592: * be prepared to remember first_kex_follows here so we can eat a
593: * packet later.
594: * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
595: * for cases where the server *doesn't* go first. I guess we should
596: * ignore it when it is set for these cases, which is what we do now.
597: */
1.102 markus 598: if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
599: (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
600: (r = sshpkt_get_end(ssh)) != 0)
601: return r;
602:
603: if (!(kex->flags & KEX_INIT_SENT))
604: if ((r = kex_send_kexinit(ssh)) != 0)
605: return r;
606: if ((r = kex_choose_conf(ssh)) != 0)
607: return r;
1.19 stevesk 608:
1.102 markus 609: if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
610: return (kex->kex[kex->kex_type])(ssh);
611:
1.160 djm 612: error_f("unknown kex type %u", kex->kex_type);
1.102 markus 613: return SSH_ERR_INTERNAL_ERROR;
614: }
615:
1.143 djm 616: struct kex *
617: kex_new(void)
1.102 markus 618: {
619: struct kex *kex;
620:
1.143 djm 621: if ((kex = calloc(1, sizeof(*kex))) == NULL ||
622: (kex->peer = sshbuf_new()) == NULL ||
623: (kex->my = sshbuf_new()) == NULL ||
624: (kex->client_version = sshbuf_new()) == NULL ||
1.165 djm 625: (kex->server_version = sshbuf_new()) == NULL ||
626: (kex->session_id = sshbuf_new()) == NULL) {
1.143 djm 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);
1.165 djm 684: sshbuf_free(kex->session_id);
1.169 ! djm 685: sshbuf_free(kex->initial_sig);
! 686: sshkey_free(kex->initial_hostkey);
1.107 djm 687: free(kex->failed_choice);
1.113 markus 688: free(kex->hostkey_alg);
689: free(kex->name);
1.102 markus 690: free(kex);
1.11 provos 691: }
692:
1.102 markus 693: int
1.143 djm 694: kex_ready(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
695: {
696: int r;
697:
698: if ((r = kex_prop2buf(ssh->kex->my, proposal)) != 0)
699: return r;
700: ssh->kex->flags = KEX_INITIAL;
701: kex_reset_dispatch(ssh);
702: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
703: return 0;
704: }
705:
706: int
1.102 markus 707: kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
1.1 markus 708: {
1.102 markus 709: int r;
1.1 markus 710:
1.143 djm 711: if ((r = kex_ready(ssh, proposal)) != 0)
1.102 markus 712: return r;
713: if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
714: kex_free(ssh->kex);
715: ssh->kex = NULL;
716: return r;
1.1 markus 717: }
1.102 markus 718: return 0;
1.117 djm 719: }
720:
721: /*
722: * Request key re-exchange, returns 0 on success or a ssherr.h error
723: * code otherwise. Must not be called if KEX is incomplete or in-progress.
724: */
725: int
726: kex_start_rekex(struct ssh *ssh)
727: {
728: if (ssh->kex == NULL) {
1.160 djm 729: error_f("no kex");
1.117 djm 730: return SSH_ERR_INTERNAL_ERROR;
731: }
732: if (ssh->kex->done == 0) {
1.160 djm 733: error_f("requested twice");
1.117 djm 734: return SSH_ERR_INTERNAL_ERROR;
735: }
736: ssh->kex->done = 0;
737: return kex_send_kexinit(ssh);
1.1 markus 738: }
739:
1.102 markus 740: static int
741: choose_enc(struct sshenc *enc, char *client, char *server)
1.1 markus 742: {
1.23 markus 743: char *name = match_list(client, server, NULL);
1.102 markus 744:
1.1 markus 745: if (name == NULL)
1.102 markus 746: return SSH_ERR_NO_CIPHER_ALG_MATCH;
1.129 dtucker 747: if ((enc->cipher = cipher_by_name(name)) == NULL) {
1.160 djm 748: error_f("unsupported cipher %s", name);
1.129 dtucker 749: free(name);
1.102 markus 750: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 751: }
1.1 markus 752: enc->name = name;
753: enc->enabled = 0;
754: enc->iv = NULL;
1.88 markus 755: enc->iv_len = cipher_ivlen(enc->cipher);
1.1 markus 756: enc->key = NULL;
1.45 markus 757: enc->key_len = cipher_keylen(enc->cipher);
758: enc->block_size = cipher_blocksize(enc->cipher);
1.102 markus 759: return 0;
1.1 markus 760: }
1.69 deraadt 761:
1.102 markus 762: static int
763: choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
1.1 markus 764: {
1.23 markus 765: char *name = match_list(client, server, NULL);
1.102 markus 766:
1.1 markus 767: if (name == NULL)
1.102 markus 768: return SSH_ERR_NO_MAC_ALG_MATCH;
1.129 dtucker 769: if (mac_setup(mac, name) < 0) {
1.160 djm 770: error_f("unsupported MAC %s", name);
1.129 dtucker 771: free(name);
1.102 markus 772: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 773: }
1.1 markus 774: mac->name = name;
775: mac->key = NULL;
776: mac->enabled = 0;
1.102 markus 777: return 0;
1.1 markus 778: }
1.69 deraadt 779:
1.102 markus 780: static int
781: choose_comp(struct sshcomp *comp, char *client, char *server)
1.1 markus 782: {
1.23 markus 783: char *name = match_list(client, server, NULL);
1.102 markus 784:
1.1 markus 785: if (name == NULL)
1.102 markus 786: return SSH_ERR_NO_COMPRESS_ALG_MATCH;
1.156 dtucker 787: #ifdef WITH_ZLIB
1.64 markus 788: if (strcmp(name, "zlib@openssh.com") == 0) {
1.141 sf 789: comp->type = COMP_DELAYED;
790: } else if (strcmp(name, "zlib") == 0) {
1.140 sf 791: comp->type = COMP_ZLIB;
1.156 dtucker 792: } else
793: #endif /* WITH_ZLIB */
794: if (strcmp(name, "none") == 0) {
1.64 markus 795: comp->type = COMP_NONE;
1.1 markus 796: } else {
1.160 djm 797: error_f("unsupported compression scheme %s", name);
1.129 dtucker 798: free(name);
1.102 markus 799: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 800: }
801: comp->name = name;
1.102 markus 802: return 0;
1.1 markus 803: }
1.69 deraadt 804:
1.102 markus 805: static int
806: choose_kex(struct kex *k, char *client, char *server)
1.1 markus 807: {
1.89 djm 808: const struct kexalg *kexalg;
809:
1.23 markus 810: k->name = match_list(client, server, NULL);
1.102 markus 811:
1.110 djm 812: debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
1.1 markus 813: if (k->name == NULL)
1.102 markus 814: return SSH_ERR_NO_KEX_ALG_MATCH;
1.152 djm 815: if ((kexalg = kex_alg_by_name(k->name)) == NULL) {
1.160 djm 816: error_f("unsupported KEX method %s", k->name);
1.102 markus 817: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 818: }
1.89 djm 819: k->kex_type = kexalg->type;
1.94 djm 820: k->hash_alg = kexalg->hash_alg;
1.89 djm 821: k->ec_nid = kexalg->ec_nid;
1.102 markus 822: return 0;
1.1 markus 823: }
1.65 djm 824:
1.102 markus 825: static int
826: choose_hostkeyalg(struct kex *k, char *client, char *server)
1.1 markus 827: {
1.162 djm 828: free(k->hostkey_alg);
1.113 markus 829: k->hostkey_alg = match_list(client, server, NULL);
1.102 markus 830:
1.110 djm 831: debug("kex: host key algorithm: %s",
1.113 markus 832: k->hostkey_alg ? k->hostkey_alg : "(no match)");
833: if (k->hostkey_alg == NULL)
1.102 markus 834: return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
1.113 markus 835: k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
1.152 djm 836: if (k->hostkey_type == KEY_UNSPEC) {
1.160 djm 837: error_f("unsupported hostkey algorithm %s", k->hostkey_alg);
1.102 markus 838: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 839: }
1.113 markus 840: k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
1.102 markus 841: return 0;
1.1 markus 842: }
843:
1.56 djm 844: static int
1.53 markus 845: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
846: {
847: static int check[] = {
848: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
849: };
850: int *idx;
851: char *p;
852:
853: for (idx = &check[0]; *idx != -1; idx++) {
854: if ((p = strchr(my[*idx], ',')) != NULL)
855: *p = '\0';
856: if ((p = strchr(peer[*idx], ',')) != NULL)
857: *p = '\0';
858: if (strcmp(my[*idx], peer[*idx]) != 0) {
859: debug2("proposal mismatch: my %s peer %s",
860: my[*idx], peer[*idx]);
861: return (0);
862: }
863: }
864: debug2("proposals match");
865: return (1);
866: }
867:
1.102 markus 868: static int
869: kex_choose_conf(struct ssh *ssh)
1.1 markus 870: {
1.102 markus 871: struct kex *kex = ssh->kex;
872: struct newkeys *newkeys;
873: char **my = NULL, **peer = NULL;
1.26 markus 874: char **cprop, **sprop;
1.27 markus 875: int nenc, nmac, ncomp;
1.96 dtucker 876: u_int mode, ctos, need, dh_need, authlen;
1.102 markus 877: int r, first_kex_follows;
1.1 markus 878:
1.110 djm 879: debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
880: if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
881: goto out;
882: debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
883: if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
1.102 markus 884: goto out;
1.26 markus 885:
1.27 markus 886: if (kex->server) {
1.26 markus 887: cprop=peer;
888: sprop=my;
889: } else {
890: cprop=my;
891: sprop=peer;
1.113 markus 892: }
893:
894: /* Check whether client supports ext_info_c */
1.142 djm 895: if (kex->server && (kex->flags & KEX_INITIAL)) {
1.113 markus 896: char *ext;
897:
898: ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
1.119 markus 899: kex->ext_info_c = (ext != NULL);
900: free(ext);
1.26 markus 901: }
1.1 markus 902:
1.30 markus 903: /* Algorithm Negotiation */
1.110 djm 904: if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
905: sprop[PROPOSAL_KEX_ALGS])) != 0) {
906: kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
907: peer[PROPOSAL_KEX_ALGS] = NULL;
908: goto out;
909: }
910: if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
911: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
912: kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
913: peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
914: goto out;
915: }
1.1 markus 916: for (mode = 0; mode < MODE_MAX; mode++) {
1.102 markus 917: if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
918: r = SSH_ERR_ALLOC_FAIL;
919: goto out;
920: }
1.30 markus 921: kex->newkeys[mode] = newkeys;
1.78 djm 922: ctos = (!kex->server && mode == MODE_OUT) ||
923: (kex->server && mode == MODE_IN);
1.1 markus 924: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
925: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
926: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.102 markus 927: if ((r = choose_enc(&newkeys->enc, cprop[nenc],
1.107 djm 928: sprop[nenc])) != 0) {
929: kex->failed_choice = peer[nenc];
930: peer[nenc] = NULL;
1.102 markus 931: goto out;
1.107 djm 932: }
1.102 markus 933: authlen = cipher_authlen(newkeys->enc.cipher);
1.88 markus 934: /* ignore mac for authenticated encryption */
1.102 markus 935: if (authlen == 0 &&
936: (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
1.107 djm 937: sprop[nmac])) != 0) {
938: kex->failed_choice = peer[nmac];
939: peer[nmac] = NULL;
1.102 markus 940: goto out;
1.107 djm 941: }
1.102 markus 942: if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
1.107 djm 943: sprop[ncomp])) != 0) {
944: kex->failed_choice = peer[ncomp];
945: peer[ncomp] = NULL;
1.102 markus 946: goto out;
1.107 djm 947: }
1.110 djm 948: debug("kex: %s cipher: %s MAC: %s compression: %s",
1.1 markus 949: ctos ? "client->server" : "server->client",
1.27 markus 950: newkeys->enc.name,
1.88 markus 951: authlen == 0 ? newkeys->mac.name : "<implicit>",
1.27 markus 952: newkeys->comp.name);
1.107 djm 953: }
1.96 dtucker 954: need = dh_need = 0;
1.1 markus 955: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 956: newkeys = kex->newkeys[mode];
1.120 deraadt 957: need = MAXIMUM(need, newkeys->enc.key_len);
958: need = MAXIMUM(need, newkeys->enc.block_size);
959: need = MAXIMUM(need, newkeys->enc.iv_len);
960: need = MAXIMUM(need, newkeys->mac.key_len);
961: dh_need = MAXIMUM(dh_need, cipher_seclen(newkeys->enc.cipher));
962: dh_need = MAXIMUM(dh_need, newkeys->enc.block_size);
963: dh_need = MAXIMUM(dh_need, newkeys->enc.iv_len);
964: dh_need = MAXIMUM(dh_need, newkeys->mac.key_len);
1.1 markus 965: }
1.7 markus 966: /* XXX need runden? */
1.27 markus 967: kex->we_need = need;
1.96 dtucker 968: kex->dh_need = dh_need;
1.53 markus 969:
970: /* ignore the next message if the proposals do not match */
1.135 djm 971: if (first_kex_follows && !proposals_match(my, peer))
1.102 markus 972: ssh->dispatch_skip_packets = 1;
973: r = 0;
974: out:
1.26 markus 975: kex_prop_free(my);
976: kex_prop_free(peer);
1.102 markus 977: return r;
1.26 markus 978: }
979:
1.102 markus 980: static int
981: derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
982: const struct sshbuf *shared_secret, u_char **keyp)
1.26 markus 983: {
1.102 markus 984: struct kex *kex = ssh->kex;
985: struct ssh_digest_ctx *hashctx = NULL;
1.26 markus 986: char c = id;
1.61 djm 987: u_int have;
1.94 djm 988: size_t mdsz;
1.61 djm 989: u_char *digest;
1.102 markus 990: int r;
1.62 djm 991:
1.94 djm 992: if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
1.102 markus 993: return SSH_ERR_INVALID_ARGUMENT;
1.120 deraadt 994: if ((digest = calloc(1, ROUNDUP(need, mdsz))) == NULL) {
1.102 markus 995: r = SSH_ERR_ALLOC_FAIL;
996: goto out;
997: }
1.26 markus 998:
1.30 markus 999: /* K1 = HASH(K || H || "A" || session_id) */
1.102 markus 1000: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1001: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 1002: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1003: ssh_digest_update(hashctx, &c, 1) != 0 ||
1.165 djm 1004: ssh_digest_update_buffer(hashctx, kex->session_id) != 0 ||
1.102 markus 1005: ssh_digest_final(hashctx, digest, mdsz) != 0) {
1006: r = SSH_ERR_LIBCRYPTO_ERROR;
1.160 djm 1007: error_f("KEX hash failed");
1.102 markus 1008: goto out;
1009: }
1.94 djm 1010: ssh_digest_free(hashctx);
1.102 markus 1011: hashctx = NULL;
1.26 markus 1012:
1.30 markus 1013: /*
1014: * expand key:
1015: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
1016: * Key = K1 || K2 || ... || Kn
1017: */
1.26 markus 1018: for (have = mdsz; need > have; have += mdsz) {
1.102 markus 1019: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1020: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 1021: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1.102 markus 1022: ssh_digest_update(hashctx, digest, have) != 0 ||
1023: ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
1.160 djm 1024: error_f("KDF failed");
1.102 markus 1025: r = SSH_ERR_LIBCRYPTO_ERROR;
1026: goto out;
1027: }
1.94 djm 1028: ssh_digest_free(hashctx);
1.102 markus 1029: hashctx = NULL;
1.26 markus 1030: }
1031: #ifdef DEBUG_KEX
1032: fprintf(stderr, "key '%c'== ", c);
1033: dump_digest("key", digest, need);
1034: #endif
1.102 markus 1035: *keyp = digest;
1036: digest = NULL;
1037: r = 0;
1038: out:
1.114 mmcc 1039: free(digest);
1.102 markus 1040: ssh_digest_free(hashctx);
1041: return r;
1.1 markus 1042: }
1043:
1.23 markus 1044: #define NKEYS 6
1.102 markus 1045: int
1046: kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
1047: const struct sshbuf *shared_secret)
1.1 markus 1048: {
1.102 markus 1049: struct kex *kex = ssh->kex;
1.15 markus 1050: u_char *keys[NKEYS];
1.102 markus 1051: u_int i, j, mode, ctos;
1052: int r;
1.1 markus 1053:
1.144 djm 1054: /* save initial hash as session id */
1.165 djm 1055: if ((kex->flags & KEX_INITIAL) != 0) {
1.166 djm 1056: if (sshbuf_len(kex->session_id) != 0) {
1057: error_f("already have session ID at kex");
1058: return SSH_ERR_INTERNAL_ERROR;
1059: }
1.165 djm 1060: if ((r = sshbuf_put(kex->session_id, hash, hashlen)) != 0)
1061: return r;
1062: } else if (sshbuf_len(kex->session_id) == 0) {
1063: error_f("no session ID in rekex");
1.166 djm 1064: return SSH_ERR_INTERNAL_ERROR;
1.144 djm 1065: }
1.65 djm 1066: for (i = 0; i < NKEYS; i++) {
1.102 markus 1067: if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
1068: shared_secret, &keys[i])) != 0) {
1069: for (j = 0; j < i; j++)
1070: free(keys[j]);
1071: return r;
1072: }
1.65 djm 1073: }
1.1 markus 1074: for (mode = 0; mode < MODE_MAX; mode++) {
1.69 deraadt 1075: ctos = (!kex->server && mode == MODE_OUT) ||
1076: (kex->server && mode == MODE_IN);
1.100 markus 1077: kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
1078: kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
1079: kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 1080: }
1.102 markus 1081: return 0;
1.95 djm 1082: }
1.57 djm 1083:
1.145 djm 1084: int
1.150 djm 1085: kex_load_hostkey(struct ssh *ssh, struct sshkey **prvp, struct sshkey **pubp)
1.145 djm 1086: {
1087: struct kex *kex = ssh->kex;
1088:
1089: *pubp = NULL;
1090: *prvp = NULL;
1091: if (kex->load_host_public_key == NULL ||
1.152 djm 1092: kex->load_host_private_key == NULL) {
1.160 djm 1093: error_f("missing hostkey loader");
1.145 djm 1094: return SSH_ERR_INVALID_ARGUMENT;
1.152 djm 1095: }
1.145 djm 1096: *pubp = kex->load_host_public_key(kex->hostkey_type,
1097: kex->hostkey_nid, ssh);
1098: *prvp = kex->load_host_private_key(kex->hostkey_type,
1099: kex->hostkey_nid, ssh);
1100: if (*pubp == NULL)
1101: return SSH_ERR_NO_HOSTKEY_LOADED;
1.146 djm 1102: return 0;
1103: }
1104:
1105: int
1106: kex_verify_host_key(struct ssh *ssh, struct sshkey *server_host_key)
1107: {
1108: struct kex *kex = ssh->kex;
1109:
1.152 djm 1110: if (kex->verify_host_key == NULL) {
1.160 djm 1111: error_f("missing hostkey verifier");
1.146 djm 1112: return SSH_ERR_INVALID_ARGUMENT;
1.152 djm 1113: }
1.146 djm 1114: if (server_host_key->type != kex->hostkey_type ||
1115: (kex->hostkey_type == KEY_ECDSA &&
1116: server_host_key->ecdsa_nid != kex->hostkey_nid))
1117: return SSH_ERR_KEY_TYPE_MISMATCH;
1118: if (kex->verify_host_key(server_host_key, ssh) == -1)
1119: return SSH_ERR_SIGNATURE_INVALID;
1.145 djm 1120: return 0;
1121: }
1.26 markus 1122:
1.84 djm 1123: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1.26 markus 1124: void
1.147 djm 1125: dump_digest(const char *msg, const u_char *digest, int len)
1.26 markus 1126: {
1127: fprintf(stderr, "%s\n", msg);
1.102 markus 1128: sshbuf_dump_data(digest, len, stderr);
1.26 markus 1129: }
1130: #endif
1.143 djm 1131:
1132: /*
1133: * Send a plaintext error message to the peer, suffixed by \r\n.
1134: * Only used during banner exchange, and there only for the server.
1135: */
1136: static void
1137: send_error(struct ssh *ssh, char *msg)
1138: {
1139: char *crnl = "\r\n";
1140:
1141: if (!ssh->kex->server)
1142: return;
1143:
1144: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1145: msg, strlen(msg)) != strlen(msg) ||
1146: atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1147: crnl, strlen(crnl)) != strlen(crnl))
1.160 djm 1148: error_f("write: %.100s", strerror(errno));
1.143 djm 1149: }
1150:
1151: /*
1152: * Sends our identification string and waits for the peer's. Will block for
1153: * up to timeout_ms (or indefinitely if timeout_ms <= 0).
1154: * Returns on 0 success or a ssherr.h code on failure.
1155: */
1156: int
1157: kex_exchange_identification(struct ssh *ssh, int timeout_ms,
1158: const char *version_addendum)
1159: {
1.158 djm 1160: int remote_major, remote_minor, mismatch, oerrno = 0;
1.143 djm 1161: size_t len, i, n;
1162: int r, expect_nl;
1163: u_char c;
1164: struct sshbuf *our_version = ssh->kex->server ?
1165: ssh->kex->server_version : ssh->kex->client_version;
1166: struct sshbuf *peer_version = ssh->kex->server ?
1167: ssh->kex->client_version : ssh->kex->server_version;
1168: char *our_version_string = NULL, *peer_version_string = NULL;
1169: char *cp, *remote_version = NULL;
1170:
1171: /* Prepare and send our banner */
1172: sshbuf_reset(our_version);
1173: if (version_addendum != NULL && *version_addendum == '\0')
1174: version_addendum = NULL;
1175: if ((r = sshbuf_putf(our_version, "SSH-%d.%d-%.100s%s%s\r\n",
1.168 djm 1176: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
1.143 djm 1177: version_addendum == NULL ? "" : " ",
1178: version_addendum == NULL ? "" : version_addendum)) != 0) {
1.158 djm 1179: oerrno = errno;
1.160 djm 1180: error_fr(r, "sshbuf_putf");
1.143 djm 1181: goto out;
1182: }
1183:
1184: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1185: sshbuf_mutable_ptr(our_version),
1186: sshbuf_len(our_version)) != sshbuf_len(our_version)) {
1.158 djm 1187: oerrno = errno;
1.160 djm 1188: debug_f("write: %.100s", strerror(errno));
1.143 djm 1189: r = SSH_ERR_SYSTEM_ERROR;
1190: goto out;
1191: }
1192: if ((r = sshbuf_consume_end(our_version, 2)) != 0) { /* trim \r\n */
1.158 djm 1193: oerrno = errno;
1.160 djm 1194: error_fr(r, "sshbuf_consume_end");
1.143 djm 1195: goto out;
1196: }
1197: our_version_string = sshbuf_dup_string(our_version);
1198: if (our_version_string == NULL) {
1.160 djm 1199: error_f("sshbuf_dup_string failed");
1.143 djm 1200: r = SSH_ERR_ALLOC_FAIL;
1201: goto out;
1202: }
1203: debug("Local version string %.100s", our_version_string);
1204:
1205: /* Read other side's version identification. */
1206: for (n = 0; ; n++) {
1207: if (n >= SSH_MAX_PRE_BANNER_LINES) {
1208: send_error(ssh, "No SSH identification string "
1209: "received.");
1.160 djm 1210: error_f("No SSH version received in first %u lines "
1211: "from server", SSH_MAX_PRE_BANNER_LINES);
1.143 djm 1212: r = SSH_ERR_INVALID_FORMAT;
1213: goto out;
1214: }
1215: sshbuf_reset(peer_version);
1216: expect_nl = 0;
1217: for (i = 0; ; i++) {
1218: if (timeout_ms > 0) {
1219: r = waitrfd(ssh_packet_get_connection_in(ssh),
1220: &timeout_ms);
1221: if (r == -1 && errno == ETIMEDOUT) {
1222: send_error(ssh, "Timed out waiting "
1223: "for SSH identification string.");
1224: error("Connection timed out during "
1225: "banner exchange");
1226: r = SSH_ERR_CONN_TIMEOUT;
1227: goto out;
1228: } else if (r == -1) {
1.158 djm 1229: oerrno = errno;
1.160 djm 1230: error_f("%s", strerror(errno));
1.143 djm 1231: r = SSH_ERR_SYSTEM_ERROR;
1232: goto out;
1233: }
1234: }
1235:
1236: len = atomicio(read, ssh_packet_get_connection_in(ssh),
1237: &c, 1);
1238: if (len != 1 && errno == EPIPE) {
1.160 djm 1239: error_f("Connection closed by remote host");
1.143 djm 1240: r = SSH_ERR_CONN_CLOSED;
1241: goto out;
1242: } else if (len != 1) {
1.158 djm 1243: oerrno = errno;
1.160 djm 1244: error_f("read: %.100s", strerror(errno));
1.143 djm 1245: r = SSH_ERR_SYSTEM_ERROR;
1246: goto out;
1247: }
1248: if (c == '\r') {
1249: expect_nl = 1;
1250: continue;
1251: }
1252: if (c == '\n')
1253: break;
1254: if (c == '\0' || expect_nl) {
1.160 djm 1255: error_f("banner line contains invalid "
1256: "characters");
1.143 djm 1257: goto invalid;
1258: }
1259: if ((r = sshbuf_put_u8(peer_version, c)) != 0) {
1.158 djm 1260: oerrno = errno;
1.160 djm 1261: error_fr(r, "sshbuf_put");
1.143 djm 1262: goto out;
1263: }
1264: if (sshbuf_len(peer_version) > SSH_MAX_BANNER_LEN) {
1.160 djm 1265: error_f("banner line too long");
1.143 djm 1266: goto invalid;
1267: }
1268: }
1269: /* Is this an actual protocol banner? */
1270: if (sshbuf_len(peer_version) > 4 &&
1271: memcmp(sshbuf_ptr(peer_version), "SSH-", 4) == 0)
1272: break;
1273: /* If not, then just log the line and continue */
1274: if ((cp = sshbuf_dup_string(peer_version)) == NULL) {
1.160 djm 1275: error_f("sshbuf_dup_string failed");
1.143 djm 1276: r = SSH_ERR_ALLOC_FAIL;
1277: goto out;
1278: }
1279: /* Do not accept lines before the SSH ident from a client */
1280: if (ssh->kex->server) {
1.160 djm 1281: error_f("client sent invalid protocol identifier "
1282: "\"%.256s\"", cp);
1.143 djm 1283: free(cp);
1284: goto invalid;
1285: }
1.160 djm 1286: debug_f("banner line %zu: %s", n, cp);
1.143 djm 1287: free(cp);
1288: }
1289: peer_version_string = sshbuf_dup_string(peer_version);
1290: if (peer_version_string == NULL)
1.160 djm 1291: error_f("sshbuf_dup_string failed");
1.143 djm 1292: /* XXX must be same size for sscanf */
1293: if ((remote_version = calloc(1, sshbuf_len(peer_version))) == NULL) {
1.160 djm 1294: error_f("calloc failed");
1.143 djm 1295: r = SSH_ERR_ALLOC_FAIL;
1296: goto out;
1297: }
1298:
1299: /*
1300: * Check that the versions match. In future this might accept
1301: * several versions and set appropriate flags to handle them.
1302: */
1303: if (sscanf(peer_version_string, "SSH-%d.%d-%[^\n]\n",
1304: &remote_major, &remote_minor, remote_version) != 3) {
1305: error("Bad remote protocol version identification: '%.100s'",
1306: peer_version_string);
1307: invalid:
1308: send_error(ssh, "Invalid SSH identification string.");
1309: r = SSH_ERR_INVALID_FORMAT;
1310: goto out;
1311: }
1312: debug("Remote protocol version %d.%d, remote software version %.100s",
1313: remote_major, remote_minor, remote_version);
1.164 djm 1314: compat_banner(ssh, remote_version);
1.143 djm 1315:
1316: mismatch = 0;
1317: switch (remote_major) {
1318: case 2:
1319: break;
1320: case 1:
1321: if (remote_minor != 99)
1322: mismatch = 1;
1323: break;
1324: default:
1325: mismatch = 1;
1326: break;
1327: }
1328: if (mismatch) {
1329: error("Protocol major versions differ: %d vs. %d",
1330: PROTOCOL_MAJOR_2, remote_major);
1331: send_error(ssh, "Protocol major versions differ.");
1332: r = SSH_ERR_NO_PROTOCOL_VERSION;
1333: goto out;
1334: }
1335:
1336: if (ssh->kex->server && (ssh->compat & SSH_BUG_PROBE) != 0) {
1337: logit("probed from %s port %d with %s. Don't panic.",
1338: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1339: peer_version_string);
1340: r = SSH_ERR_CONN_CLOSED; /* XXX */
1341: goto out;
1342: }
1343: if (ssh->kex->server && (ssh->compat & SSH_BUG_SCANNER) != 0) {
1344: logit("scanned from %s port %d with %s. Don't panic.",
1345: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1346: peer_version_string);
1347: r = SSH_ERR_CONN_CLOSED; /* XXX */
1348: goto out;
1349: }
1350: if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
1351: logit("Remote version \"%.100s\" uses unsafe RSA signature "
1352: "scheme; disabling use of RSA keys", remote_version);
1353: }
1354: /* success */
1355: r = 0;
1356: out:
1357: free(our_version_string);
1358: free(peer_version_string);
1359: free(remote_version);
1.158 djm 1360: if (r == SSH_ERR_SYSTEM_ERROR)
1361: errno = oerrno;
1.143 djm 1362: return r;
1363: }
1364:
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