Annotation of src/usr.bin/ssh/kex.c, Revision 1.153
1.153 ! djm 1: /* $OpenBSD: kex.c,v 1.152 2019/09/05 09:35:19 djm Exp $ */
1.1 markus 2: /*
1.36 markus 3: * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
1.1 markus 4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24: */
25:
1.18 markus 26:
1.143 djm 27: #include <sys/types.h>
28: #include <errno.h>
1.76 deraadt 29: #include <signal.h>
1.75 stevesk 30: #include <stdio.h>
1.74 stevesk 31: #include <stdlib.h>
1.72 stevesk 32: #include <string.h>
1.143 djm 33: #include <unistd.h>
34: #include <poll.h>
1.1 markus 35:
1.99 markus 36: #ifdef WITH_OPENSSL
1.76 deraadt 37: #include <openssl/crypto.h>
1.99 markus 38: #endif
1.76 deraadt 39:
1.143 djm 40: #include "ssh.h"
1.1 markus 41: #include "ssh2.h"
1.143 djm 42: #include "atomicio.h"
43: #include "version.h"
1.7 markus 44: #include "packet.h"
1.1 markus 45: #include "compat.h"
1.18 markus 46: #include "cipher.h"
1.102 markus 47: #include "sshkey.h"
1.1 markus 48: #include "kex.h"
1.18 markus 49: #include "log.h"
1.21 markus 50: #include "mac.h"
1.23 markus 51: #include "match.h"
1.102 markus 52: #include "misc.h"
1.26 markus 53: #include "dispatch.h"
1.48 provos 54: #include "monitor.h"
1.102 markus 55:
56: #include "ssherr.h"
57: #include "sshbuf.h"
1.94 djm 58: #include "digest.h"
1.48 provos 59:
1.35 itojun 60: /* prototype */
1.102 markus 61: static int kex_choose_conf(struct ssh *);
1.133 markus 62: static int kex_input_newkeys(int, u_int32_t, struct ssh *);
1.86 djm 63:
1.110 djm 64: static const char *proposal_names[PROPOSAL_MAX] = {
65: "KEX algorithms",
66: "host key algorithms",
67: "ciphers ctos",
68: "ciphers stoc",
69: "MACs ctos",
70: "MACs stoc",
71: "compression ctos",
72: "compression stoc",
73: "languages ctos",
74: "languages stoc",
75: };
76:
1.89 djm 77: struct kexalg {
78: char *name;
1.102 markus 79: u_int type;
1.89 djm 80: int ec_nid;
1.94 djm 81: int hash_alg;
1.89 djm 82: };
83: static const struct kexalg kexalgs[] = {
1.99 markus 84: #ifdef WITH_OPENSSL
1.94 djm 85: { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
1.118 djm 86: { KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
87: { KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
88: { KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
89: { KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
1.94 djm 90: { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
91: { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
92: { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
93: NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
94: { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
95: SSH_DIGEST_SHA384 },
96: { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
97: SSH_DIGEST_SHA512 },
1.99 markus 98: #endif
1.94 djm 99: { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
1.124 djm 100: { KEX_CURVE25519_SHA256_OLD, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
1.147 djm 101: { KEX_SNTRUP4591761X25519_SHA512, KEX_KEM_SNTRUP4591761X25519_SHA512, 0,
102: SSH_DIGEST_SHA512 },
1.94 djm 103: { NULL, -1, -1, -1},
1.89 djm 104: };
105:
106: char *
1.93 dtucker 107: kex_alg_list(char sep)
1.89 djm 108: {
1.102 markus 109: char *ret = NULL, *tmp;
1.89 djm 110: size_t nlen, rlen = 0;
111: const struct kexalg *k;
112:
113: for (k = kexalgs; k->name != NULL; k++) {
114: if (ret != NULL)
1.93 dtucker 115: ret[rlen++] = sep;
1.89 djm 116: nlen = strlen(k->name);
1.102 markus 117: if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
118: free(ret);
119: return NULL;
120: }
121: ret = tmp;
1.89 djm 122: memcpy(ret + rlen, k->name, nlen + 1);
123: rlen += nlen;
124: }
125: return ret;
126: }
127:
128: static const struct kexalg *
129: kex_alg_by_name(const char *name)
130: {
131: const struct kexalg *k;
132:
133: for (k = kexalgs; k->name != NULL; k++) {
134: if (strcmp(k->name, name) == 0)
135: return k;
136: }
137: return NULL;
138: }
139:
1.86 djm 140: /* Validate KEX method name list */
141: int
142: kex_names_valid(const char *names)
143: {
144: char *s, *cp, *p;
145:
146: if (names == NULL || strcmp(names, "") == 0)
147: return 0;
1.102 markus 148: if ((s = cp = strdup(names)) == NULL)
149: return 0;
1.86 djm 150: for ((p = strsep(&cp, ",")); p && *p != '\0';
151: (p = strsep(&cp, ","))) {
1.89 djm 152: if (kex_alg_by_name(p) == NULL) {
1.86 djm 153: error("Unsupported KEX algorithm \"%.100s\"", p);
1.91 djm 154: free(s);
1.86 djm 155: return 0;
156: }
157: }
158: debug3("kex names ok: [%s]", names);
1.91 djm 159: free(s);
1.86 djm 160: return 1;
1.109 djm 161: }
162:
163: /*
164: * Concatenate algorithm names, avoiding duplicates in the process.
165: * Caller must free returned string.
166: */
167: char *
168: kex_names_cat(const char *a, const char *b)
169: {
1.129 dtucker 170: char *ret = NULL, *tmp = NULL, *cp, *p, *m;
1.109 djm 171: size_t len;
172:
173: if (a == NULL || *a == '\0')
1.138 djm 174: return strdup(b);
1.109 djm 175: if (b == NULL || *b == '\0')
176: return strdup(a);
177: if (strlen(b) > 1024*1024)
178: return NULL;
179: len = strlen(a) + strlen(b) + 2;
180: if ((tmp = cp = strdup(b)) == NULL ||
181: (ret = calloc(1, len)) == NULL) {
182: free(tmp);
183: return NULL;
184: }
185: strlcpy(ret, a, len);
186: for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
1.129 dtucker 187: if ((m = match_list(ret, p, NULL)) != NULL) {
188: free(m);
1.109 djm 189: continue; /* Algorithm already present */
1.129 dtucker 190: }
1.109 djm 191: if (strlcat(ret, ",", len) >= len ||
192: strlcat(ret, p, len) >= len) {
193: free(tmp);
194: free(ret);
195: return NULL; /* Shouldn't happen */
196: }
197: }
198: free(tmp);
199: return ret;
200: }
201:
202: /*
203: * Assemble a list of algorithms from a default list and a string from a
204: * configuration file. The user-provided string may begin with '+' to
1.128 djm 205: * indicate that it should be appended to the default or '-' that the
206: * specified names should be removed.
1.109 djm 207: */
208: int
1.138 djm 209: kex_assemble_names(char **listp, const char *def, const char *all)
1.109 djm 210: {
1.138 djm 211: char *cp, *tmp, *patterns;
212: char *list = NULL, *ret = NULL, *matching = NULL, *opatterns = NULL;
213: int r = SSH_ERR_INTERNAL_ERROR;
214:
1.153 ! djm 215: if (listp == NULL || def == NULL || all == NULL)
! 216: return SSH_ERR_INVALID_ARGUMENT;
! 217:
! 218: if (*listp == NULL || **listp == '\0') {
1.138 djm 219: if ((*listp = strdup(def)) == NULL)
220: return SSH_ERR_ALLOC_FAIL;
221: return 0;
222: }
1.109 djm 223:
1.138 djm 224: list = *listp;
225: *listp = NULL;
226: if (*list == '+') {
227: /* Append names to default list */
228: if ((tmp = kex_names_cat(def, list + 1)) == NULL) {
229: r = SSH_ERR_ALLOC_FAIL;
230: goto fail;
231: }
232: free(list);
233: list = tmp;
234: } else if (*list == '-') {
235: /* Remove names from default list */
236: if ((*listp = match_filter_blacklist(def, list + 1)) == NULL) {
237: r = SSH_ERR_ALLOC_FAIL;
238: goto fail;
239: }
240: free(list);
241: /* filtering has already been done */
1.109 djm 242: return 0;
1.138 djm 243: } else {
244: /* Explicit list, overrides default - just use "list" as is */
245: }
246:
247: /*
248: * The supplied names may be a pattern-list. For the -list case,
249: * the patterns are applied above. For the +list and explicit list
250: * cases we need to do it now.
251: */
252: ret = NULL;
253: if ((patterns = opatterns = strdup(list)) == NULL) {
254: r = SSH_ERR_ALLOC_FAIL;
255: goto fail;
256: }
257: /* Apply positive (i.e. non-negated) patterns from the list */
258: while ((cp = strsep(&patterns, ",")) != NULL) {
259: if (*cp == '!') {
260: /* negated matches are not supported here */
261: r = SSH_ERR_INVALID_ARGUMENT;
262: goto fail;
263: }
264: free(matching);
265: if ((matching = match_filter_whitelist(all, cp)) == NULL) {
266: r = SSH_ERR_ALLOC_FAIL;
267: goto fail;
268: }
269: if ((tmp = kex_names_cat(ret, matching)) == NULL) {
270: r = SSH_ERR_ALLOC_FAIL;
271: goto fail;
272: }
273: free(ret);
274: ret = tmp;
1.109 djm 275: }
1.138 djm 276: if (ret == NULL || *ret == '\0') {
277: /* An empty name-list is an error */
278: /* XXX better error code? */
279: r = SSH_ERR_INVALID_ARGUMENT;
280: goto fail;
1.109 djm 281: }
282:
1.138 djm 283: /* success */
284: *listp = ret;
285: ret = NULL;
286: r = 0;
287:
288: fail:
289: free(matching);
290: free(opatterns);
291: free(list);
292: free(ret);
293: return r;
1.86 djm 294: }
1.26 markus 295:
296: /* put algorithm proposal into buffer */
1.102 markus 297: int
298: kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
1.1 markus 299: {
1.61 djm 300: u_int i;
1.102 markus 301: int r;
302:
303: sshbuf_reset(b);
1.26 markus 304:
1.49 markus 305: /*
306: * add a dummy cookie, the cookie will be overwritten by
307: * kex_send_kexinit(), each time a kexinit is set
308: */
1.102 markus 309: for (i = 0; i < KEX_COOKIE_LEN; i++) {
310: if ((r = sshbuf_put_u8(b, 0)) != 0)
311: return r;
312: }
313: for (i = 0; i < PROPOSAL_MAX; i++) {
314: if ((r = sshbuf_put_cstring(b, proposal[i])) != 0)
315: return r;
316: }
317: if ((r = sshbuf_put_u8(b, 0)) != 0 || /* first_kex_packet_follows */
318: (r = sshbuf_put_u32(b, 0)) != 0) /* uint32 reserved */
319: return r;
320: return 0;
1.1 markus 321: }
322:
1.26 markus 323: /* parse buffer and return algorithm proposal */
1.102 markus 324: int
325: kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
1.7 markus 326: {
1.102 markus 327: struct sshbuf *b = NULL;
328: u_char v;
1.78 djm 329: u_int i;
1.102 markus 330: char **proposal = NULL;
331: int r;
1.7 markus 332:
1.102 markus 333: *propp = NULL;
334: if ((proposal = calloc(PROPOSAL_MAX, sizeof(char *))) == NULL)
335: return SSH_ERR_ALLOC_FAIL;
336: if ((b = sshbuf_fromb(raw)) == NULL) {
337: r = SSH_ERR_ALLOC_FAIL;
338: goto out;
339: }
1.152 djm 340: if ((r = sshbuf_consume(b, KEX_COOKIE_LEN)) != 0) { /* skip cookie */
341: error("%s: consume cookie: %s", __func__, ssh_err(r));
1.102 markus 342: goto out;
1.152 djm 343: }
1.7 markus 344: /* extract kex init proposal strings */
345: for (i = 0; i < PROPOSAL_MAX; i++) {
1.152 djm 346: if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0) {
347: error("%s: parse proposal %u: %s", __func__,
348: i, ssh_err(r));
1.102 markus 349: goto out;
1.152 djm 350: }
1.110 djm 351: debug2("%s: %s", proposal_names[i], proposal[i]);
1.7 markus 352: }
1.26 markus 353: /* first kex follows / reserved */
1.115 djm 354: if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
1.152 djm 355: (r = sshbuf_get_u32(b, &i)) != 0) { /* reserved */
356: error("%s: parse: %s", __func__, ssh_err(r));
1.102 markus 357: goto out;
1.152 djm 358: }
1.53 markus 359: if (first_kex_follows != NULL)
1.115 djm 360: *first_kex_follows = v;
1.110 djm 361: debug2("first_kex_follows %d ", v);
362: debug2("reserved %u ", i);
1.102 markus 363: r = 0;
364: *propp = proposal;
365: out:
366: if (r != 0 && proposal != NULL)
367: kex_prop_free(proposal);
368: sshbuf_free(b);
369: return r;
1.1 markus 370: }
371:
1.102 markus 372: void
1.26 markus 373: kex_prop_free(char **proposal)
1.1 markus 374: {
1.61 djm 375: u_int i;
1.26 markus 376:
1.106 djm 377: if (proposal == NULL)
378: return;
1.26 markus 379: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 djm 380: free(proposal[i]);
381: free(proposal);
1.1 markus 382: }
383:
1.78 djm 384: /* ARGSUSED */
1.101 markus 385: static int
1.133 markus 386: kex_protocol_error(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 387: {
1.112 djm 388: int r;
389:
390: error("kex protocol error: type %d seq %u", type, seq);
391: if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
392: (r = sshpkt_put_u32(ssh, seq)) != 0 ||
393: (r = sshpkt_send(ssh)) != 0)
394: return r;
1.101 markus 395: return 0;
1.26 markus 396: }
1.1 markus 397:
1.35 itojun 398: static void
1.102 markus 399: kex_reset_dispatch(struct ssh *ssh)
1.29 markus 400: {
1.102 markus 401: ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
1.42 markus 402: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.29 markus 403: }
404:
1.113 markus 405: static int
406: kex_send_ext_info(struct ssh *ssh)
407: {
408: int r;
1.121 djm 409: char *algs;
1.113 markus 410:
1.151 djm 411: debug("Sending SSH2_MSG_EXT_INFO");
1.130 djm 412: if ((algs = sshkey_alg_list(0, 1, 1, ',')) == NULL)
1.121 djm 413: return SSH_ERR_ALLOC_FAIL;
1.137 djm 414: /* XXX filter algs list by allowed pubkey/hostbased types */
1.113 markus 415: if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
416: (r = sshpkt_put_u32(ssh, 1)) != 0 ||
417: (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 ||
1.121 djm 418: (r = sshpkt_put_cstring(ssh, algs)) != 0 ||
1.152 djm 419: (r = sshpkt_send(ssh)) != 0) {
420: error("%s: compose: %s", __func__, ssh_err(r));
1.121 djm 421: goto out;
1.152 djm 422: }
1.121 djm 423: /* success */
424: r = 0;
425: out:
426: free(algs);
1.123 djm 427: return r;
1.113 markus 428: }
429:
1.102 markus 430: int
431: kex_send_newkeys(struct ssh *ssh)
1.26 markus 432: {
1.102 markus 433: int r;
1.28 markus 434:
1.102 markus 435: kex_reset_dispatch(ssh);
436: if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
437: (r = sshpkt_send(ssh)) != 0)
438: return r;
1.26 markus 439: debug("SSH2_MSG_NEWKEYS sent");
1.102 markus 440: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
1.151 djm 441: if (ssh->kex->ext_info_c && (ssh->kex->flags & KEX_INITIAL) != 0)
1.113 markus 442: if ((r = kex_send_ext_info(ssh)) != 0)
443: return r;
1.151 djm 444: debug("expecting SSH2_MSG_NEWKEYS");
1.102 markus 445: return 0;
446: }
447:
1.113 markus 448: int
1.133 markus 449: kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
1.113 markus 450: {
451: struct kex *kex = ssh->kex;
452: u_int32_t i, ninfo;
1.137 djm 453: char *name;
1.134 djm 454: u_char *val;
455: size_t vlen;
1.113 markus 456: int r;
457:
458: debug("SSH2_MSG_EXT_INFO received");
459: ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
460: if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
461: return r;
462: for (i = 0; i < ninfo; i++) {
463: if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
464: return r;
1.134 djm 465: if ((r = sshpkt_get_string(ssh, &val, &vlen)) != 0) {
1.113 markus 466: free(name);
467: return r;
468: }
469: if (strcmp(name, "server-sig-algs") == 0) {
1.134 djm 470: /* Ensure no \0 lurking in value */
471: if (memchr(val, '\0', vlen) != NULL) {
472: error("%s: nul byte in %s", __func__, name);
473: return SSH_ERR_INVALID_FORMAT;
474: }
475: debug("%s: %s=<%s>", __func__, name, val);
1.137 djm 476: kex->server_sig_algs = val;
477: val = NULL;
1.134 djm 478: } else
479: debug("%s: %s (unrecognised)", __func__, name);
1.113 markus 480: free(name);
481: free(val);
482: }
483: return sshpkt_get_end(ssh);
484: }
485:
1.102 markus 486: static int
1.133 markus 487: kex_input_newkeys(int type, u_int32_t seq, struct ssh *ssh)
1.102 markus 488: {
489: struct kex *kex = ssh->kex;
490: int r;
1.19 stevesk 491:
1.26 markus 492: debug("SSH2_MSG_NEWKEYS received");
1.102 markus 493: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
1.131 markus 494: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.102 markus 495: if ((r = sshpkt_get_end(ssh)) != 0)
1.122 markus 496: return r;
497: if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
1.102 markus 498: return r;
1.30 markus 499: kex->done = 1;
1.142 djm 500: kex->flags &= ~KEX_INITIAL;
1.102 markus 501: sshbuf_reset(kex->peer);
502: /* sshbuf_reset(kex->my); */
1.26 markus 503: kex->flags &= ~KEX_INIT_SENT;
1.91 djm 504: free(kex->name);
1.32 markus 505: kex->name = NULL;
1.102 markus 506: return 0;
1.26 markus 507: }
1.1 markus 508:
1.102 markus 509: int
510: kex_send_kexinit(struct ssh *ssh)
1.26 markus 511: {
1.49 markus 512: u_char *cookie;
1.102 markus 513: struct kex *kex = ssh->kex;
514: int r;
1.49 markus 515:
1.152 djm 516: if (kex == NULL) {
517: error("%s: no hex", __func__);
1.102 markus 518: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 519: }
1.102 markus 520: if (kex->flags & KEX_INIT_SENT)
521: return 0;
1.30 markus 522: kex->done = 0;
1.49 markus 523:
524: /* generate a random cookie */
1.152 djm 525: if (sshbuf_len(kex->my) < KEX_COOKIE_LEN) {
526: error("%s: bad kex length: %zu < %d", __func__,
527: sshbuf_len(kex->my), KEX_COOKIE_LEN);
1.102 markus 528: return SSH_ERR_INVALID_FORMAT;
1.152 djm 529: }
530: if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL) {
531: error("%s: buffer error", __func__);
1.102 markus 532: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 533: }
1.102 markus 534: arc4random_buf(cookie, KEX_COOKIE_LEN);
535:
536: if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
537: (r = sshpkt_putb(ssh, kex->my)) != 0 ||
1.152 djm 538: (r = sshpkt_send(ssh)) != 0) {
539: error("%s: compose reply: %s", __func__, ssh_err(r));
1.102 markus 540: return r;
1.152 djm 541: }
1.26 markus 542: debug("SSH2_MSG_KEXINIT sent");
543: kex->flags |= KEX_INIT_SENT;
1.102 markus 544: return 0;
1.1 markus 545: }
546:
1.78 djm 547: /* ARGSUSED */
1.101 markus 548: int
1.133 markus 549: kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
1.11 provos 550: {
1.102 markus 551: struct kex *kex = ssh->kex;
552: const u_char *ptr;
1.100 markus 553: u_int i;
554: size_t dlen;
1.102 markus 555: int r;
1.11 provos 556:
1.26 markus 557: debug("SSH2_MSG_KEXINIT received");
1.152 djm 558: if (kex == NULL) {
559: error("%s: no hex", __func__);
560: return SSH_ERR_INTERNAL_ERROR;
561: }
1.127 markus 562: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, NULL);
1.102 markus 563: ptr = sshpkt_ptr(ssh, &dlen);
564: if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
565: return r;
1.31 markus 566:
567: /* discard packet */
1.152 djm 568: for (i = 0; i < KEX_COOKIE_LEN; i++) {
569: if ((r = sshpkt_get_u8(ssh, NULL)) != 0) {
570: error("%s: discard cookie: %s", __func__, ssh_err(r));
1.102 markus 571: return r;
1.152 djm 572: }
573: }
574: for (i = 0; i < PROPOSAL_MAX; i++) {
575: if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
576: error("%s: discard proposal: %s", __func__, ssh_err(r));
1.102 markus 577: return r;
1.152 djm 578: }
579: }
1.87 djm 580: /*
581: * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
582: * KEX method has the server move first, but a server might be using
583: * a custom method or one that we otherwise don't support. We should
584: * be prepared to remember first_kex_follows here so we can eat a
585: * packet later.
586: * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
587: * for cases where the server *doesn't* go first. I guess we should
588: * ignore it when it is set for these cases, which is what we do now.
589: */
1.102 markus 590: if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
591: (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
592: (r = sshpkt_get_end(ssh)) != 0)
593: return r;
594:
595: if (!(kex->flags & KEX_INIT_SENT))
596: if ((r = kex_send_kexinit(ssh)) != 0)
597: return r;
598: if ((r = kex_choose_conf(ssh)) != 0)
599: return r;
1.19 stevesk 600:
1.102 markus 601: if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
602: return (kex->kex[kex->kex_type])(ssh);
603:
1.152 djm 604: error("%s: unknown kex type %u", __func__, kex->kex_type);
1.102 markus 605: return SSH_ERR_INTERNAL_ERROR;
606: }
607:
1.143 djm 608: struct kex *
609: kex_new(void)
1.102 markus 610: {
611: struct kex *kex;
612:
1.143 djm 613: if ((kex = calloc(1, sizeof(*kex))) == NULL ||
614: (kex->peer = sshbuf_new()) == NULL ||
615: (kex->my = sshbuf_new()) == NULL ||
616: (kex->client_version = sshbuf_new()) == NULL ||
617: (kex->server_version = sshbuf_new()) == NULL) {
618: kex_free(kex);
619: return NULL;
1.102 markus 620: }
1.143 djm 621: return kex;
1.26 markus 622: }
1.11 provos 623:
1.100 markus 624: void
625: kex_free_newkeys(struct newkeys *newkeys)
626: {
627: if (newkeys == NULL)
628: return;
629: if (newkeys->enc.key) {
630: explicit_bzero(newkeys->enc.key, newkeys->enc.key_len);
631: free(newkeys->enc.key);
632: newkeys->enc.key = NULL;
633: }
634: if (newkeys->enc.iv) {
1.111 djm 635: explicit_bzero(newkeys->enc.iv, newkeys->enc.iv_len);
1.100 markus 636: free(newkeys->enc.iv);
637: newkeys->enc.iv = NULL;
638: }
639: free(newkeys->enc.name);
640: explicit_bzero(&newkeys->enc, sizeof(newkeys->enc));
641: free(newkeys->comp.name);
642: explicit_bzero(&newkeys->comp, sizeof(newkeys->comp));
643: mac_clear(&newkeys->mac);
644: if (newkeys->mac.key) {
645: explicit_bzero(newkeys->mac.key, newkeys->mac.key_len);
646: free(newkeys->mac.key);
647: newkeys->mac.key = NULL;
648: }
649: free(newkeys->mac.name);
650: explicit_bzero(&newkeys->mac, sizeof(newkeys->mac));
651: explicit_bzero(newkeys, sizeof(*newkeys));
652: free(newkeys);
653: }
654:
1.102 markus 655: void
656: kex_free(struct kex *kex)
1.26 markus 657: {
1.102 markus 658: u_int mode;
1.11 provos 659:
1.143 djm 660: if (kex == NULL)
661: return;
662:
1.102 markus 663: #ifdef WITH_OPENSSL
1.136 jsing 664: DH_free(kex->dh);
665: EC_KEY_free(kex->ec_client_key);
1.102 markus 666: #endif
667: for (mode = 0; mode < MODE_MAX; mode++) {
668: kex_free_newkeys(kex->newkeys[mode]);
669: kex->newkeys[mode] = NULL;
1.100 markus 670: }
1.102 markus 671: sshbuf_free(kex->peer);
672: sshbuf_free(kex->my);
1.143 djm 673: sshbuf_free(kex->client_version);
674: sshbuf_free(kex->server_version);
1.149 djm 675: sshbuf_free(kex->client_pub);
1.102 markus 676: free(kex->session_id);
1.107 djm 677: free(kex->failed_choice);
1.113 markus 678: free(kex->hostkey_alg);
679: free(kex->name);
1.102 markus 680: free(kex);
1.11 provos 681: }
682:
1.102 markus 683: int
1.143 djm 684: kex_ready(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
685: {
686: int r;
687:
688: if ((r = kex_prop2buf(ssh->kex->my, proposal)) != 0)
689: return r;
690: ssh->kex->flags = KEX_INITIAL;
691: kex_reset_dispatch(ssh);
692: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
693: return 0;
694: }
695:
696: int
1.102 markus 697: kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
1.1 markus 698: {
1.102 markus 699: int r;
1.1 markus 700:
1.143 djm 701: if ((r = kex_ready(ssh, proposal)) != 0)
1.102 markus 702: return r;
703: if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
704: kex_free(ssh->kex);
705: ssh->kex = NULL;
706: return r;
1.1 markus 707: }
1.102 markus 708: return 0;
1.117 djm 709: }
710:
711: /*
712: * Request key re-exchange, returns 0 on success or a ssherr.h error
713: * code otherwise. Must not be called if KEX is incomplete or in-progress.
714: */
715: int
716: kex_start_rekex(struct ssh *ssh)
717: {
718: if (ssh->kex == NULL) {
719: error("%s: no kex", __func__);
720: return SSH_ERR_INTERNAL_ERROR;
721: }
722: if (ssh->kex->done == 0) {
723: error("%s: requested twice", __func__);
724: return SSH_ERR_INTERNAL_ERROR;
725: }
726: ssh->kex->done = 0;
727: return kex_send_kexinit(ssh);
1.1 markus 728: }
729:
1.102 markus 730: static int
731: choose_enc(struct sshenc *enc, char *client, char *server)
1.1 markus 732: {
1.23 markus 733: char *name = match_list(client, server, NULL);
1.102 markus 734:
1.1 markus 735: if (name == NULL)
1.102 markus 736: return SSH_ERR_NO_CIPHER_ALG_MATCH;
1.129 dtucker 737: if ((enc->cipher = cipher_by_name(name)) == NULL) {
1.152 djm 738: error("%s: unsupported cipher %s", __func__, name);
1.129 dtucker 739: free(name);
1.102 markus 740: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 741: }
1.1 markus 742: enc->name = name;
743: enc->enabled = 0;
744: enc->iv = NULL;
1.88 markus 745: enc->iv_len = cipher_ivlen(enc->cipher);
1.1 markus 746: enc->key = NULL;
1.45 markus 747: enc->key_len = cipher_keylen(enc->cipher);
748: enc->block_size = cipher_blocksize(enc->cipher);
1.102 markus 749: return 0;
1.1 markus 750: }
1.69 deraadt 751:
1.102 markus 752: static int
753: choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
1.1 markus 754: {
1.23 markus 755: char *name = match_list(client, server, NULL);
1.102 markus 756:
1.1 markus 757: if (name == NULL)
1.102 markus 758: return SSH_ERR_NO_MAC_ALG_MATCH;
1.129 dtucker 759: if (mac_setup(mac, name) < 0) {
1.152 djm 760: error("%s: unsupported MAC %s", __func__, name);
1.129 dtucker 761: free(name);
1.102 markus 762: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 763: }
1.1 markus 764: mac->name = name;
765: mac->key = NULL;
766: mac->enabled = 0;
1.102 markus 767: return 0;
1.1 markus 768: }
1.69 deraadt 769:
1.102 markus 770: static int
771: choose_comp(struct sshcomp *comp, char *client, char *server)
1.1 markus 772: {
1.23 markus 773: char *name = match_list(client, server, NULL);
1.102 markus 774:
1.1 markus 775: if (name == NULL)
1.102 markus 776: return SSH_ERR_NO_COMPRESS_ALG_MATCH;
1.64 markus 777: if (strcmp(name, "zlib@openssh.com") == 0) {
1.141 sf 778: comp->type = COMP_DELAYED;
779: } else if (strcmp(name, "zlib") == 0) {
1.140 sf 780: comp->type = COMP_ZLIB;
1.1 markus 781: } else if (strcmp(name, "none") == 0) {
1.64 markus 782: comp->type = COMP_NONE;
1.1 markus 783: } else {
1.152 djm 784: error("%s: unsupported compression scheme %s", __func__, name);
1.129 dtucker 785: free(name);
1.102 markus 786: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 787: }
788: comp->name = name;
1.102 markus 789: return 0;
1.1 markus 790: }
1.69 deraadt 791:
1.102 markus 792: static int
793: choose_kex(struct kex *k, char *client, char *server)
1.1 markus 794: {
1.89 djm 795: const struct kexalg *kexalg;
796:
1.23 markus 797: k->name = match_list(client, server, NULL);
1.102 markus 798:
1.110 djm 799: debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
1.1 markus 800: if (k->name == NULL)
1.102 markus 801: return SSH_ERR_NO_KEX_ALG_MATCH;
1.152 djm 802: if ((kexalg = kex_alg_by_name(k->name)) == NULL) {
803: error("%s: unsupported KEX method %s", __func__, k->name);
1.102 markus 804: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 805: }
1.89 djm 806: k->kex_type = kexalg->type;
1.94 djm 807: k->hash_alg = kexalg->hash_alg;
1.89 djm 808: k->ec_nid = kexalg->ec_nid;
1.102 markus 809: return 0;
1.1 markus 810: }
1.65 djm 811:
1.102 markus 812: static int
813: choose_hostkeyalg(struct kex *k, char *client, char *server)
1.1 markus 814: {
1.113 markus 815: k->hostkey_alg = match_list(client, server, NULL);
1.102 markus 816:
1.110 djm 817: debug("kex: host key algorithm: %s",
1.113 markus 818: k->hostkey_alg ? k->hostkey_alg : "(no match)");
819: if (k->hostkey_alg == NULL)
1.102 markus 820: return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
1.113 markus 821: k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
1.152 djm 822: if (k->hostkey_type == KEY_UNSPEC) {
823: error("%s: unsupported hostkey algorithm %s", __func__,
824: k->hostkey_alg);
1.102 markus 825: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 826: }
1.113 markus 827: k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
1.102 markus 828: return 0;
1.1 markus 829: }
830:
1.56 djm 831: static int
1.53 markus 832: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
833: {
834: static int check[] = {
835: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
836: };
837: int *idx;
838: char *p;
839:
840: for (idx = &check[0]; *idx != -1; idx++) {
841: if ((p = strchr(my[*idx], ',')) != NULL)
842: *p = '\0';
843: if ((p = strchr(peer[*idx], ',')) != NULL)
844: *p = '\0';
845: if (strcmp(my[*idx], peer[*idx]) != 0) {
846: debug2("proposal mismatch: my %s peer %s",
847: my[*idx], peer[*idx]);
848: return (0);
849: }
850: }
851: debug2("proposals match");
852: return (1);
853: }
854:
1.102 markus 855: static int
856: kex_choose_conf(struct ssh *ssh)
1.1 markus 857: {
1.102 markus 858: struct kex *kex = ssh->kex;
859: struct newkeys *newkeys;
860: char **my = NULL, **peer = NULL;
1.26 markus 861: char **cprop, **sprop;
1.27 markus 862: int nenc, nmac, ncomp;
1.96 dtucker 863: u_int mode, ctos, need, dh_need, authlen;
1.102 markus 864: int r, first_kex_follows;
1.1 markus 865:
1.110 djm 866: debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
867: if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
868: goto out;
869: debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
870: if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
1.102 markus 871: goto out;
1.26 markus 872:
1.27 markus 873: if (kex->server) {
1.26 markus 874: cprop=peer;
875: sprop=my;
876: } else {
877: cprop=my;
878: sprop=peer;
1.113 markus 879: }
880:
881: /* Check whether client supports ext_info_c */
1.142 djm 882: if (kex->server && (kex->flags & KEX_INITIAL)) {
1.113 markus 883: char *ext;
884:
885: ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
1.119 markus 886: kex->ext_info_c = (ext != NULL);
887: free(ext);
1.26 markus 888: }
1.1 markus 889:
1.30 markus 890: /* Algorithm Negotiation */
1.110 djm 891: if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
892: sprop[PROPOSAL_KEX_ALGS])) != 0) {
893: kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
894: peer[PROPOSAL_KEX_ALGS] = NULL;
895: goto out;
896: }
897: if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
898: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
899: kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
900: peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
901: goto out;
902: }
1.1 markus 903: for (mode = 0; mode < MODE_MAX; mode++) {
1.102 markus 904: if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
905: r = SSH_ERR_ALLOC_FAIL;
906: goto out;
907: }
1.30 markus 908: kex->newkeys[mode] = newkeys;
1.78 djm 909: ctos = (!kex->server && mode == MODE_OUT) ||
910: (kex->server && mode == MODE_IN);
1.1 markus 911: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
912: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
913: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.102 markus 914: if ((r = choose_enc(&newkeys->enc, cprop[nenc],
1.107 djm 915: sprop[nenc])) != 0) {
916: kex->failed_choice = peer[nenc];
917: peer[nenc] = NULL;
1.102 markus 918: goto out;
1.107 djm 919: }
1.102 markus 920: authlen = cipher_authlen(newkeys->enc.cipher);
1.88 markus 921: /* ignore mac for authenticated encryption */
1.102 markus 922: if (authlen == 0 &&
923: (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
1.107 djm 924: sprop[nmac])) != 0) {
925: kex->failed_choice = peer[nmac];
926: peer[nmac] = NULL;
1.102 markus 927: goto out;
1.107 djm 928: }
1.102 markus 929: if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
1.107 djm 930: sprop[ncomp])) != 0) {
931: kex->failed_choice = peer[ncomp];
932: peer[ncomp] = NULL;
1.102 markus 933: goto out;
1.107 djm 934: }
1.110 djm 935: debug("kex: %s cipher: %s MAC: %s compression: %s",
1.1 markus 936: ctos ? "client->server" : "server->client",
1.27 markus 937: newkeys->enc.name,
1.88 markus 938: authlen == 0 ? newkeys->mac.name : "<implicit>",
1.27 markus 939: newkeys->comp.name);
1.107 djm 940: }
1.96 dtucker 941: need = dh_need = 0;
1.1 markus 942: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 943: newkeys = kex->newkeys[mode];
1.120 deraadt 944: need = MAXIMUM(need, newkeys->enc.key_len);
945: need = MAXIMUM(need, newkeys->enc.block_size);
946: need = MAXIMUM(need, newkeys->enc.iv_len);
947: need = MAXIMUM(need, newkeys->mac.key_len);
948: dh_need = MAXIMUM(dh_need, cipher_seclen(newkeys->enc.cipher));
949: dh_need = MAXIMUM(dh_need, newkeys->enc.block_size);
950: dh_need = MAXIMUM(dh_need, newkeys->enc.iv_len);
951: dh_need = MAXIMUM(dh_need, newkeys->mac.key_len);
1.1 markus 952: }
1.7 markus 953: /* XXX need runden? */
1.27 markus 954: kex->we_need = need;
1.96 dtucker 955: kex->dh_need = dh_need;
1.53 markus 956:
957: /* ignore the next message if the proposals do not match */
1.135 djm 958: if (first_kex_follows && !proposals_match(my, peer))
1.102 markus 959: ssh->dispatch_skip_packets = 1;
960: r = 0;
961: out:
1.26 markus 962: kex_prop_free(my);
963: kex_prop_free(peer);
1.102 markus 964: return r;
1.26 markus 965: }
966:
1.102 markus 967: static int
968: derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
969: const struct sshbuf *shared_secret, u_char **keyp)
1.26 markus 970: {
1.102 markus 971: struct kex *kex = ssh->kex;
972: struct ssh_digest_ctx *hashctx = NULL;
1.26 markus 973: char c = id;
1.61 djm 974: u_int have;
1.94 djm 975: size_t mdsz;
1.61 djm 976: u_char *digest;
1.102 markus 977: int r;
1.62 djm 978:
1.94 djm 979: if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
1.102 markus 980: return SSH_ERR_INVALID_ARGUMENT;
1.120 deraadt 981: if ((digest = calloc(1, ROUNDUP(need, mdsz))) == NULL) {
1.102 markus 982: r = SSH_ERR_ALLOC_FAIL;
983: goto out;
984: }
1.26 markus 985:
1.30 markus 986: /* K1 = HASH(K || H || "A" || session_id) */
1.102 markus 987: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
988: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 989: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
990: ssh_digest_update(hashctx, &c, 1) != 0 ||
991: ssh_digest_update(hashctx, kex->session_id,
1.102 markus 992: kex->session_id_len) != 0 ||
993: ssh_digest_final(hashctx, digest, mdsz) != 0) {
994: r = SSH_ERR_LIBCRYPTO_ERROR;
1.152 djm 995: error("%s: KEX hash failed", __func__);
1.102 markus 996: goto out;
997: }
1.94 djm 998: ssh_digest_free(hashctx);
1.102 markus 999: hashctx = NULL;
1.26 markus 1000:
1.30 markus 1001: /*
1002: * expand key:
1003: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
1004: * Key = K1 || K2 || ... || Kn
1005: */
1.26 markus 1006: for (have = mdsz; need > have; have += mdsz) {
1.102 markus 1007: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1008: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 1009: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1.102 markus 1010: ssh_digest_update(hashctx, digest, have) != 0 ||
1011: ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
1.152 djm 1012: error("%s: KDF failed", __func__);
1.102 markus 1013: r = SSH_ERR_LIBCRYPTO_ERROR;
1014: goto out;
1015: }
1.94 djm 1016: ssh_digest_free(hashctx);
1.102 markus 1017: hashctx = NULL;
1.26 markus 1018: }
1019: #ifdef DEBUG_KEX
1020: fprintf(stderr, "key '%c'== ", c);
1021: dump_digest("key", digest, need);
1022: #endif
1.102 markus 1023: *keyp = digest;
1024: digest = NULL;
1025: r = 0;
1026: out:
1.114 mmcc 1027: free(digest);
1.102 markus 1028: ssh_digest_free(hashctx);
1029: return r;
1.1 markus 1030: }
1031:
1.23 markus 1032: #define NKEYS 6
1.102 markus 1033: int
1034: kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
1035: const struct sshbuf *shared_secret)
1.1 markus 1036: {
1.102 markus 1037: struct kex *kex = ssh->kex;
1.15 markus 1038: u_char *keys[NKEYS];
1.102 markus 1039: u_int i, j, mode, ctos;
1040: int r;
1.1 markus 1041:
1.144 djm 1042: /* save initial hash as session id */
1043: if (kex->session_id == NULL) {
1044: kex->session_id_len = hashlen;
1045: kex->session_id = malloc(kex->session_id_len);
1046: if (kex->session_id == NULL)
1047: return SSH_ERR_ALLOC_FAIL;
1048: memcpy(kex->session_id, hash, kex->session_id_len);
1049: }
1.65 djm 1050: for (i = 0; i < NKEYS; i++) {
1.102 markus 1051: if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
1052: shared_secret, &keys[i])) != 0) {
1053: for (j = 0; j < i; j++)
1054: free(keys[j]);
1055: return r;
1056: }
1.65 djm 1057: }
1.1 markus 1058: for (mode = 0; mode < MODE_MAX; mode++) {
1.69 deraadt 1059: ctos = (!kex->server && mode == MODE_OUT) ||
1060: (kex->server && mode == MODE_IN);
1.100 markus 1061: kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
1062: kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
1063: kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 1064: }
1.102 markus 1065: return 0;
1.95 djm 1066: }
1.57 djm 1067:
1.145 djm 1068: int
1.150 djm 1069: kex_load_hostkey(struct ssh *ssh, struct sshkey **prvp, struct sshkey **pubp)
1.145 djm 1070: {
1071: struct kex *kex = ssh->kex;
1072:
1073: *pubp = NULL;
1074: *prvp = NULL;
1075: if (kex->load_host_public_key == NULL ||
1.152 djm 1076: kex->load_host_private_key == NULL) {
1077: error("%s: missing hostkey loader", __func__);
1.145 djm 1078: return SSH_ERR_INVALID_ARGUMENT;
1.152 djm 1079: }
1.145 djm 1080: *pubp = kex->load_host_public_key(kex->hostkey_type,
1081: kex->hostkey_nid, ssh);
1082: *prvp = kex->load_host_private_key(kex->hostkey_type,
1083: kex->hostkey_nid, ssh);
1084: if (*pubp == NULL)
1085: return SSH_ERR_NO_HOSTKEY_LOADED;
1.146 djm 1086: return 0;
1087: }
1088:
1089: int
1090: kex_verify_host_key(struct ssh *ssh, struct sshkey *server_host_key)
1091: {
1092: struct kex *kex = ssh->kex;
1093:
1.152 djm 1094: if (kex->verify_host_key == NULL) {
1095: error("%s: missing hostkey verifier", __func__);
1.146 djm 1096: return SSH_ERR_INVALID_ARGUMENT;
1.152 djm 1097: }
1.146 djm 1098: if (server_host_key->type != kex->hostkey_type ||
1099: (kex->hostkey_type == KEY_ECDSA &&
1100: server_host_key->ecdsa_nid != kex->hostkey_nid))
1101: return SSH_ERR_KEY_TYPE_MISMATCH;
1102: if (kex->verify_host_key(server_host_key, ssh) == -1)
1103: return SSH_ERR_SIGNATURE_INVALID;
1.145 djm 1104: return 0;
1105: }
1.26 markus 1106:
1.84 djm 1107: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1.26 markus 1108: void
1.147 djm 1109: dump_digest(const char *msg, const u_char *digest, int len)
1.26 markus 1110: {
1111: fprintf(stderr, "%s\n", msg);
1.102 markus 1112: sshbuf_dump_data(digest, len, stderr);
1.26 markus 1113: }
1114: #endif
1.143 djm 1115:
1116: /*
1117: * Send a plaintext error message to the peer, suffixed by \r\n.
1118: * Only used during banner exchange, and there only for the server.
1119: */
1120: static void
1121: send_error(struct ssh *ssh, char *msg)
1122: {
1123: char *crnl = "\r\n";
1124:
1125: if (!ssh->kex->server)
1126: return;
1127:
1128: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1129: msg, strlen(msg)) != strlen(msg) ||
1130: atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1131: crnl, strlen(crnl)) != strlen(crnl))
1132: error("%s: write: %.100s", __func__, strerror(errno));
1133: }
1134:
1135: /*
1136: * Sends our identification string and waits for the peer's. Will block for
1137: * up to timeout_ms (or indefinitely if timeout_ms <= 0).
1138: * Returns on 0 success or a ssherr.h code on failure.
1139: */
1140: int
1141: kex_exchange_identification(struct ssh *ssh, int timeout_ms,
1142: const char *version_addendum)
1143: {
1144: int remote_major, remote_minor, mismatch;
1145: size_t len, i, n;
1146: int r, expect_nl;
1147: u_char c;
1148: struct sshbuf *our_version = ssh->kex->server ?
1149: ssh->kex->server_version : ssh->kex->client_version;
1150: struct sshbuf *peer_version = ssh->kex->server ?
1151: ssh->kex->client_version : ssh->kex->server_version;
1152: char *our_version_string = NULL, *peer_version_string = NULL;
1153: char *cp, *remote_version = NULL;
1154:
1155: /* Prepare and send our banner */
1156: sshbuf_reset(our_version);
1157: if (version_addendum != NULL && *version_addendum == '\0')
1158: version_addendum = NULL;
1159: if ((r = sshbuf_putf(our_version, "SSH-%d.%d-%.100s%s%s\r\n",
1160: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
1161: version_addendum == NULL ? "" : " ",
1162: version_addendum == NULL ? "" : version_addendum)) != 0) {
1163: error("%s: sshbuf_putf: %s", __func__, ssh_err(r));
1164: goto out;
1165: }
1166:
1167: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1168: sshbuf_mutable_ptr(our_version),
1169: sshbuf_len(our_version)) != sshbuf_len(our_version)) {
1170: error("%s: write: %.100s", __func__, strerror(errno));
1171: r = SSH_ERR_SYSTEM_ERROR;
1172: goto out;
1173: }
1174: if ((r = sshbuf_consume_end(our_version, 2)) != 0) { /* trim \r\n */
1175: error("%s: sshbuf_consume_end: %s", __func__, ssh_err(r));
1176: goto out;
1177: }
1178: our_version_string = sshbuf_dup_string(our_version);
1179: if (our_version_string == NULL) {
1180: error("%s: sshbuf_dup_string failed", __func__);
1181: r = SSH_ERR_ALLOC_FAIL;
1182: goto out;
1183: }
1184: debug("Local version string %.100s", our_version_string);
1185:
1186: /* Read other side's version identification. */
1187: for (n = 0; ; n++) {
1188: if (n >= SSH_MAX_PRE_BANNER_LINES) {
1189: send_error(ssh, "No SSH identification string "
1190: "received.");
1191: error("%s: No SSH version received in first %u lines "
1192: "from server", __func__, SSH_MAX_PRE_BANNER_LINES);
1193: r = SSH_ERR_INVALID_FORMAT;
1194: goto out;
1195: }
1196: sshbuf_reset(peer_version);
1197: expect_nl = 0;
1198: for (i = 0; ; i++) {
1199: if (timeout_ms > 0) {
1200: r = waitrfd(ssh_packet_get_connection_in(ssh),
1201: &timeout_ms);
1202: if (r == -1 && errno == ETIMEDOUT) {
1203: send_error(ssh, "Timed out waiting "
1204: "for SSH identification string.");
1205: error("Connection timed out during "
1206: "banner exchange");
1207: r = SSH_ERR_CONN_TIMEOUT;
1208: goto out;
1209: } else if (r == -1) {
1210: error("%s: %s",
1211: __func__, strerror(errno));
1212: r = SSH_ERR_SYSTEM_ERROR;
1213: goto out;
1214: }
1215: }
1216:
1217: len = atomicio(read, ssh_packet_get_connection_in(ssh),
1218: &c, 1);
1219: if (len != 1 && errno == EPIPE) {
1220: error("%s: Connection closed by remote host",
1221: __func__);
1222: r = SSH_ERR_CONN_CLOSED;
1223: goto out;
1224: } else if (len != 1) {
1225: error("%s: read: %.100s",
1226: __func__, strerror(errno));
1227: r = SSH_ERR_SYSTEM_ERROR;
1228: goto out;
1229: }
1230: if (c == '\r') {
1231: expect_nl = 1;
1232: continue;
1233: }
1234: if (c == '\n')
1235: break;
1236: if (c == '\0' || expect_nl) {
1237: error("%s: banner line contains invalid "
1238: "characters", __func__);
1239: goto invalid;
1240: }
1241: if ((r = sshbuf_put_u8(peer_version, c)) != 0) {
1242: error("%s: sshbuf_put: %s",
1243: __func__, ssh_err(r));
1244: goto out;
1245: }
1246: if (sshbuf_len(peer_version) > SSH_MAX_BANNER_LEN) {
1247: error("%s: banner line too long", __func__);
1248: goto invalid;
1249: }
1250: }
1251: /* Is this an actual protocol banner? */
1252: if (sshbuf_len(peer_version) > 4 &&
1253: memcmp(sshbuf_ptr(peer_version), "SSH-", 4) == 0)
1254: break;
1255: /* If not, then just log the line and continue */
1256: if ((cp = sshbuf_dup_string(peer_version)) == NULL) {
1257: error("%s: sshbuf_dup_string failed", __func__);
1258: r = SSH_ERR_ALLOC_FAIL;
1259: goto out;
1260: }
1261: /* Do not accept lines before the SSH ident from a client */
1262: if (ssh->kex->server) {
1263: error("%s: client sent invalid protocol identifier "
1264: "\"%.256s\"", __func__, cp);
1265: free(cp);
1266: goto invalid;
1267: }
1268: debug("%s: banner line %zu: %s", __func__, n, cp);
1269: free(cp);
1270: }
1271: peer_version_string = sshbuf_dup_string(peer_version);
1272: if (peer_version_string == NULL)
1273: error("%s: sshbuf_dup_string failed", __func__);
1274: /* XXX must be same size for sscanf */
1275: if ((remote_version = calloc(1, sshbuf_len(peer_version))) == NULL) {
1276: error("%s: calloc failed", __func__);
1277: r = SSH_ERR_ALLOC_FAIL;
1278: goto out;
1279: }
1280:
1281: /*
1282: * Check that the versions match. In future this might accept
1283: * several versions and set appropriate flags to handle them.
1284: */
1285: if (sscanf(peer_version_string, "SSH-%d.%d-%[^\n]\n",
1286: &remote_major, &remote_minor, remote_version) != 3) {
1287: error("Bad remote protocol version identification: '%.100s'",
1288: peer_version_string);
1289: invalid:
1290: send_error(ssh, "Invalid SSH identification string.");
1291: r = SSH_ERR_INVALID_FORMAT;
1292: goto out;
1293: }
1294: debug("Remote protocol version %d.%d, remote software version %.100s",
1295: remote_major, remote_minor, remote_version);
1296: ssh->compat = compat_datafellows(remote_version);
1297:
1298: mismatch = 0;
1299: switch (remote_major) {
1300: case 2:
1301: break;
1302: case 1:
1303: if (remote_minor != 99)
1304: mismatch = 1;
1305: break;
1306: default:
1307: mismatch = 1;
1308: break;
1309: }
1310: if (mismatch) {
1311: error("Protocol major versions differ: %d vs. %d",
1312: PROTOCOL_MAJOR_2, remote_major);
1313: send_error(ssh, "Protocol major versions differ.");
1314: r = SSH_ERR_NO_PROTOCOL_VERSION;
1315: goto out;
1316: }
1317:
1318: if (ssh->kex->server && (ssh->compat & SSH_BUG_PROBE) != 0) {
1319: logit("probed from %s port %d with %s. Don't panic.",
1320: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1321: peer_version_string);
1322: r = SSH_ERR_CONN_CLOSED; /* XXX */
1323: goto out;
1324: }
1325: if (ssh->kex->server && (ssh->compat & SSH_BUG_SCANNER) != 0) {
1326: logit("scanned from %s port %d with %s. Don't panic.",
1327: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1328: peer_version_string);
1329: r = SSH_ERR_CONN_CLOSED; /* XXX */
1330: goto out;
1331: }
1332: if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
1333: logit("Remote version \"%.100s\" uses unsafe RSA signature "
1334: "scheme; disabling use of RSA keys", remote_version);
1335: }
1336: /* success */
1337: r = 0;
1338: out:
1339: free(our_version_string);
1340: free(peer_version_string);
1341: free(remote_version);
1342: return r;
1343: }
1344:
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