Annotation of src/usr.bin/ssh/kex.c, Revision 1.179
1.179 ! djm 1: /* $OpenBSD: kex.c,v 1.178 2023/03/12 10:40:39 dtucker 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"
1.176 dtucker 55: #include "myproposal.h"
1.102 markus 56:
57: #include "ssherr.h"
58: #include "sshbuf.h"
1.94 djm 59: #include "digest.h"
1.176 dtucker 60: #include "xmalloc.h"
1.48 provos 61:
1.35 itojun 62: /* prototype */
1.102 markus 63: static int kex_choose_conf(struct ssh *);
1.133 markus 64: static int kex_input_newkeys(int, u_int32_t, struct ssh *);
1.86 djm 65:
1.172 djm 66: static const char * const proposal_names[PROPOSAL_MAX] = {
1.110 djm 67: "KEX algorithms",
68: "host key algorithms",
69: "ciphers ctos",
70: "ciphers stoc",
71: "MACs ctos",
72: "MACs stoc",
73: "compression ctos",
74: "compression stoc",
75: "languages ctos",
76: "languages stoc",
77: };
78:
1.89 djm 79: struct kexalg {
80: char *name;
1.102 markus 81: u_int type;
1.89 djm 82: int ec_nid;
1.94 djm 83: int hash_alg;
1.89 djm 84: };
85: static const struct kexalg kexalgs[] = {
1.99 markus 86: #ifdef WITH_OPENSSL
1.94 djm 87: { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
1.118 djm 88: { KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
89: { KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
90: { KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
91: { KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
1.94 djm 92: { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
93: { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
94: { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
95: NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
96: { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
97: SSH_DIGEST_SHA384 },
98: { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
99: SSH_DIGEST_SHA512 },
1.99 markus 100: #endif
1.94 djm 101: { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
1.124 djm 102: { KEX_CURVE25519_SHA256_OLD, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
1.163 djm 103: { KEX_SNTRUP761X25519_SHA512, KEX_KEM_SNTRUP761X25519_SHA512, 0,
1.147 djm 104: SSH_DIGEST_SHA512 },
1.155 dtucker 105: { NULL, 0, -1, -1},
1.89 djm 106: };
107:
108: char *
1.93 dtucker 109: kex_alg_list(char sep)
1.89 djm 110: {
1.102 markus 111: char *ret = NULL, *tmp;
1.89 djm 112: size_t nlen, rlen = 0;
113: const struct kexalg *k;
114:
115: for (k = kexalgs; k->name != NULL; k++) {
116: if (ret != NULL)
1.93 dtucker 117: ret[rlen++] = sep;
1.89 djm 118: nlen = strlen(k->name);
1.102 markus 119: if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
120: free(ret);
121: return NULL;
122: }
123: ret = tmp;
1.89 djm 124: memcpy(ret + rlen, k->name, nlen + 1);
125: rlen += nlen;
126: }
127: return ret;
128: }
129:
130: static const struct kexalg *
131: kex_alg_by_name(const char *name)
132: {
133: const struct kexalg *k;
134:
135: for (k = kexalgs; k->name != NULL; k++) {
136: if (strcmp(k->name, name) == 0)
137: return k;
138: }
139: return NULL;
140: }
141:
1.86 djm 142: /* Validate KEX method name list */
143: int
144: kex_names_valid(const char *names)
145: {
146: char *s, *cp, *p;
147:
148: if (names == NULL || strcmp(names, "") == 0)
149: return 0;
1.102 markus 150: if ((s = cp = strdup(names)) == NULL)
151: return 0;
1.86 djm 152: for ((p = strsep(&cp, ",")); p && *p != '\0';
153: (p = strsep(&cp, ","))) {
1.89 djm 154: if (kex_alg_by_name(p) == NULL) {
1.86 djm 155: error("Unsupported KEX algorithm \"%.100s\"", p);
1.91 djm 156: free(s);
1.86 djm 157: return 0;
158: }
159: }
160: debug3("kex names ok: [%s]", names);
1.91 djm 161: free(s);
1.86 djm 162: return 1;
1.109 djm 163: }
164:
165: /*
166: * Concatenate algorithm names, avoiding duplicates in the process.
167: * Caller must free returned string.
168: */
169: char *
170: kex_names_cat(const char *a, const char *b)
171: {
1.129 dtucker 172: char *ret = NULL, *tmp = NULL, *cp, *p, *m;
1.109 djm 173: size_t len;
174:
175: if (a == NULL || *a == '\0')
1.138 djm 176: return strdup(b);
1.109 djm 177: if (b == NULL || *b == '\0')
178: return strdup(a);
179: if (strlen(b) > 1024*1024)
180: return NULL;
181: len = strlen(a) + strlen(b) + 2;
182: if ((tmp = cp = strdup(b)) == NULL ||
183: (ret = calloc(1, len)) == NULL) {
184: free(tmp);
185: return NULL;
186: }
187: strlcpy(ret, a, len);
188: for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
1.129 dtucker 189: if ((m = match_list(ret, p, NULL)) != NULL) {
190: free(m);
1.109 djm 191: continue; /* Algorithm already present */
1.129 dtucker 192: }
1.109 djm 193: if (strlcat(ret, ",", len) >= len ||
194: strlcat(ret, p, len) >= len) {
195: free(tmp);
196: free(ret);
197: return NULL; /* Shouldn't happen */
198: }
199: }
200: free(tmp);
201: return ret;
202: }
203:
204: /*
205: * Assemble a list of algorithms from a default list and a string from a
206: * configuration file. The user-provided string may begin with '+' to
1.154 naddy 207: * indicate that it should be appended to the default, '-' that the
208: * specified names should be removed, or '^' that they should be placed
209: * at the head.
1.109 djm 210: */
211: int
1.138 djm 212: kex_assemble_names(char **listp, const char *def, const char *all)
1.109 djm 213: {
1.138 djm 214: char *cp, *tmp, *patterns;
215: char *list = NULL, *ret = NULL, *matching = NULL, *opatterns = NULL;
216: int r = SSH_ERR_INTERNAL_ERROR;
217:
1.153 djm 218: if (listp == NULL || def == NULL || all == NULL)
219: return SSH_ERR_INVALID_ARGUMENT;
220:
221: if (*listp == NULL || **listp == '\0') {
1.138 djm 222: if ((*listp = strdup(def)) == NULL)
223: return SSH_ERR_ALLOC_FAIL;
224: return 0;
225: }
1.109 djm 226:
1.138 djm 227: list = *listp;
228: *listp = NULL;
229: if (*list == '+') {
230: /* Append names to default list */
231: if ((tmp = kex_names_cat(def, list + 1)) == NULL) {
232: r = SSH_ERR_ALLOC_FAIL;
233: goto fail;
234: }
235: free(list);
236: list = tmp;
237: } else if (*list == '-') {
238: /* Remove names from default list */
1.159 djm 239: if ((*listp = match_filter_denylist(def, list + 1)) == NULL) {
1.138 djm 240: r = SSH_ERR_ALLOC_FAIL;
241: goto fail;
242: }
243: free(list);
244: /* filtering has already been done */
1.109 djm 245: return 0;
1.154 naddy 246: } else if (*list == '^') {
247: /* Place names at head of default list */
248: if ((tmp = kex_names_cat(list + 1, def)) == NULL) {
249: r = SSH_ERR_ALLOC_FAIL;
250: goto fail;
251: }
252: free(list);
253: list = tmp;
1.138 djm 254: } else {
255: /* Explicit list, overrides default - just use "list" as is */
256: }
257:
258: /*
259: * The supplied names may be a pattern-list. For the -list case,
260: * the patterns are applied above. For the +list and explicit list
261: * cases we need to do it now.
262: */
263: ret = NULL;
264: if ((patterns = opatterns = strdup(list)) == NULL) {
265: r = SSH_ERR_ALLOC_FAIL;
266: goto fail;
267: }
268: /* Apply positive (i.e. non-negated) patterns from the list */
269: while ((cp = strsep(&patterns, ",")) != NULL) {
270: if (*cp == '!') {
271: /* negated matches are not supported here */
272: r = SSH_ERR_INVALID_ARGUMENT;
273: goto fail;
274: }
275: free(matching);
1.159 djm 276: if ((matching = match_filter_allowlist(all, cp)) == NULL) {
1.138 djm 277: r = SSH_ERR_ALLOC_FAIL;
278: goto fail;
279: }
280: if ((tmp = kex_names_cat(ret, matching)) == NULL) {
281: r = SSH_ERR_ALLOC_FAIL;
282: goto fail;
283: }
284: free(ret);
285: ret = tmp;
1.109 djm 286: }
1.138 djm 287: if (ret == NULL || *ret == '\0') {
288: /* An empty name-list is an error */
289: /* XXX better error code? */
290: r = SSH_ERR_INVALID_ARGUMENT;
291: goto fail;
1.109 djm 292: }
293:
1.138 djm 294: /* success */
295: *listp = ret;
296: ret = NULL;
297: r = 0;
298:
299: fail:
300: free(matching);
301: free(opatterns);
302: free(list);
303: free(ret);
304: return r;
1.176 dtucker 305: }
306:
307: /*
308: * Fill out a proposal array with dynamically allocated values, which may
309: * be modified as required for compatibility reasons.
310: * Any of the options may be NULL, in which case the default is used.
311: * Array contents must be freed by calling kex_proposal_free_entries.
312: */
313: void
314: kex_proposal_populate_entries(struct ssh *ssh, char *prop[PROPOSAL_MAX],
315: const char *kexalgos, const char *ciphers, const char *macs,
316: const char *comp, const char *hkalgs)
317: {
318: const char *defpropserver[PROPOSAL_MAX] = { KEX_SERVER };
319: const char *defpropclient[PROPOSAL_MAX] = { KEX_CLIENT };
320: const char **defprop = ssh->kex->server ? defpropserver : defpropclient;
321: u_int i;
322:
323: if (prop == NULL)
324: fatal_f("proposal missing");
325:
326: for (i = 0; i < PROPOSAL_MAX; i++) {
327: switch(i) {
328: case PROPOSAL_KEX_ALGS:
329: prop[i] = compat_kex_proposal(ssh,
330: kexalgos ? kexalgos : defprop[i]);
331: break;
332: case PROPOSAL_ENC_ALGS_CTOS:
333: case PROPOSAL_ENC_ALGS_STOC:
334: prop[i] = xstrdup(ciphers ? ciphers : defprop[i]);
335: break;
336: case PROPOSAL_MAC_ALGS_CTOS:
337: case PROPOSAL_MAC_ALGS_STOC:
338: prop[i] = xstrdup(macs ? macs : defprop[i]);
339: break;
340: case PROPOSAL_COMP_ALGS_CTOS:
341: case PROPOSAL_COMP_ALGS_STOC:
342: prop[i] = xstrdup(comp ? comp : defprop[i]);
343: break;
344: case PROPOSAL_SERVER_HOST_KEY_ALGS:
345: prop[i] = xstrdup(hkalgs ? hkalgs : defprop[i]);
346: break;
347: default:
348: prop[i] = xstrdup(defprop[i]);
349: }
350: }
351: }
352:
353: void
354: kex_proposal_free_entries(char *prop[PROPOSAL_MAX])
355: {
356: u_int i;
357:
358: for (i = 0; i < PROPOSAL_MAX; i++)
359: free(prop[i]);
1.86 djm 360: }
1.26 markus 361:
362: /* put algorithm proposal into buffer */
1.102 markus 363: int
364: kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
1.1 markus 365: {
1.61 djm 366: u_int i;
1.102 markus 367: int r;
368:
369: sshbuf_reset(b);
1.26 markus 370:
1.49 markus 371: /*
372: * add a dummy cookie, the cookie will be overwritten by
373: * kex_send_kexinit(), each time a kexinit is set
374: */
1.102 markus 375: for (i = 0; i < KEX_COOKIE_LEN; i++) {
376: if ((r = sshbuf_put_u8(b, 0)) != 0)
377: return r;
378: }
379: for (i = 0; i < PROPOSAL_MAX; i++) {
380: if ((r = sshbuf_put_cstring(b, proposal[i])) != 0)
381: return r;
382: }
383: if ((r = sshbuf_put_u8(b, 0)) != 0 || /* first_kex_packet_follows */
384: (r = sshbuf_put_u32(b, 0)) != 0) /* uint32 reserved */
385: return r;
386: return 0;
1.1 markus 387: }
388:
1.26 markus 389: /* parse buffer and return algorithm proposal */
1.102 markus 390: int
391: kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
1.7 markus 392: {
1.102 markus 393: struct sshbuf *b = NULL;
394: u_char v;
1.78 djm 395: u_int i;
1.102 markus 396: char **proposal = NULL;
397: int r;
1.7 markus 398:
1.102 markus 399: *propp = NULL;
400: if ((proposal = calloc(PROPOSAL_MAX, sizeof(char *))) == NULL)
401: return SSH_ERR_ALLOC_FAIL;
402: if ((b = sshbuf_fromb(raw)) == NULL) {
403: r = SSH_ERR_ALLOC_FAIL;
404: goto out;
405: }
1.152 djm 406: if ((r = sshbuf_consume(b, KEX_COOKIE_LEN)) != 0) { /* skip cookie */
1.160 djm 407: error_fr(r, "consume cookie");
1.102 markus 408: goto out;
1.152 djm 409: }
1.7 markus 410: /* extract kex init proposal strings */
411: for (i = 0; i < PROPOSAL_MAX; i++) {
1.152 djm 412: if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0) {
1.160 djm 413: error_fr(r, "parse proposal %u", i);
1.102 markus 414: goto out;
1.152 djm 415: }
1.110 djm 416: debug2("%s: %s", proposal_names[i], proposal[i]);
1.7 markus 417: }
1.26 markus 418: /* first kex follows / reserved */
1.115 djm 419: if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
1.152 djm 420: (r = sshbuf_get_u32(b, &i)) != 0) { /* reserved */
1.160 djm 421: error_fr(r, "parse");
1.102 markus 422: goto out;
1.152 djm 423: }
1.53 markus 424: if (first_kex_follows != NULL)
1.115 djm 425: *first_kex_follows = v;
1.110 djm 426: debug2("first_kex_follows %d ", v);
427: debug2("reserved %u ", i);
1.102 markus 428: r = 0;
429: *propp = proposal;
430: out:
431: if (r != 0 && proposal != NULL)
432: kex_prop_free(proposal);
433: sshbuf_free(b);
434: return r;
1.1 markus 435: }
436:
1.102 markus 437: void
1.26 markus 438: kex_prop_free(char **proposal)
1.1 markus 439: {
1.61 djm 440: u_int i;
1.26 markus 441:
1.106 djm 442: if (proposal == NULL)
443: return;
1.26 markus 444: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 djm 445: free(proposal[i]);
446: free(proposal);
1.1 markus 447: }
448:
1.167 djm 449: int
1.133 markus 450: kex_protocol_error(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 451: {
1.112 djm 452: int r;
453:
454: error("kex protocol error: type %d seq %u", type, seq);
455: if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
456: (r = sshpkt_put_u32(ssh, seq)) != 0 ||
457: (r = sshpkt_send(ssh)) != 0)
458: return r;
1.101 markus 459: return 0;
1.26 markus 460: }
1.1 markus 461:
1.35 itojun 462: static void
1.102 markus 463: kex_reset_dispatch(struct ssh *ssh)
1.29 markus 464: {
1.102 markus 465: ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
1.42 markus 466: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.29 markus 467: }
468:
1.113 markus 469: static int
470: kex_send_ext_info(struct ssh *ssh)
471: {
472: int r;
1.121 djm 473: char *algs;
1.113 markus 474:
1.151 djm 475: debug("Sending SSH2_MSG_EXT_INFO");
1.130 djm 476: if ((algs = sshkey_alg_list(0, 1, 1, ',')) == NULL)
1.121 djm 477: return SSH_ERR_ALLOC_FAIL;
1.137 djm 478: /* XXX filter algs list by allowed pubkey/hostbased types */
1.113 markus 479: if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
1.170 djm 480: (r = sshpkt_put_u32(ssh, 2)) != 0 ||
1.113 markus 481: (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 ||
1.121 djm 482: (r = sshpkt_put_cstring(ssh, algs)) != 0 ||
1.170 djm 483: (r = sshpkt_put_cstring(ssh,
484: "publickey-hostbound@openssh.com")) != 0 ||
485: (r = sshpkt_put_cstring(ssh, "0")) != 0 ||
1.152 djm 486: (r = sshpkt_send(ssh)) != 0) {
1.160 djm 487: error_fr(r, "compose");
1.121 djm 488: goto out;
1.152 djm 489: }
1.121 djm 490: /* success */
491: r = 0;
492: out:
493: free(algs);
1.123 djm 494: return r;
1.113 markus 495: }
496:
1.102 markus 497: int
498: kex_send_newkeys(struct ssh *ssh)
1.26 markus 499: {
1.102 markus 500: int r;
1.28 markus 501:
1.102 markus 502: kex_reset_dispatch(ssh);
503: if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
504: (r = sshpkt_send(ssh)) != 0)
505: return r;
1.26 markus 506: debug("SSH2_MSG_NEWKEYS sent");
1.102 markus 507: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
1.151 djm 508: if (ssh->kex->ext_info_c && (ssh->kex->flags & KEX_INITIAL) != 0)
1.113 markus 509: if ((r = kex_send_ext_info(ssh)) != 0)
510: return r;
1.151 djm 511: debug("expecting SSH2_MSG_NEWKEYS");
1.102 markus 512: return 0;
513: }
514:
1.113 markus 515: int
1.133 markus 516: kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
1.113 markus 517: {
518: struct kex *kex = ssh->kex;
519: u_int32_t i, ninfo;
1.137 djm 520: char *name;
1.134 djm 521: u_char *val;
522: size_t vlen;
1.113 markus 523: int r;
524:
525: debug("SSH2_MSG_EXT_INFO received");
526: ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
527: if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
528: return r;
1.178 dtucker 529: if (ninfo >= 1024) {
530: error("SSH2_MSG_EXT_INFO with too many entries, expected "
531: "<=1024, received %u", ninfo);
532: return SSH_ERR_INVALID_FORMAT;
533: }
1.113 markus 534: for (i = 0; i < ninfo; i++) {
535: if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
536: return r;
1.134 djm 537: if ((r = sshpkt_get_string(ssh, &val, &vlen)) != 0) {
1.113 markus 538: free(name);
539: return r;
540: }
541: if (strcmp(name, "server-sig-algs") == 0) {
1.134 djm 542: /* Ensure no \0 lurking in value */
543: if (memchr(val, '\0', vlen) != NULL) {
1.160 djm 544: error_f("nul byte in %s", name);
1.134 djm 545: return SSH_ERR_INVALID_FORMAT;
546: }
1.160 djm 547: debug_f("%s=<%s>", name, val);
1.137 djm 548: kex->server_sig_algs = val;
549: val = NULL;
1.170 djm 550: } else if (strcmp(name,
551: "publickey-hostbound@openssh.com") == 0) {
552: /* XXX refactor */
553: /* Ensure no \0 lurking in value */
554: if (memchr(val, '\0', vlen) != NULL) {
555: error_f("nul byte in %s", name);
556: return SSH_ERR_INVALID_FORMAT;
557: }
558: debug_f("%s=<%s>", name, val);
559: if (strcmp(val, "0") == 0)
560: kex->flags |= KEX_HAS_PUBKEY_HOSTBOUND;
561: else {
562: debug_f("unsupported version of %s extension",
563: name);
564: }
1.134 djm 565: } else
1.160 djm 566: debug_f("%s (unrecognised)", name);
1.113 markus 567: free(name);
568: free(val);
569: }
570: return sshpkt_get_end(ssh);
571: }
572:
1.102 markus 573: static int
1.133 markus 574: kex_input_newkeys(int type, u_int32_t seq, struct ssh *ssh)
1.102 markus 575: {
576: struct kex *kex = ssh->kex;
577: int r;
1.19 stevesk 578:
1.26 markus 579: debug("SSH2_MSG_NEWKEYS received");
1.102 markus 580: ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
1.131 markus 581: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.102 markus 582: if ((r = sshpkt_get_end(ssh)) != 0)
1.122 markus 583: return r;
584: if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
1.102 markus 585: return r;
1.30 markus 586: kex->done = 1;
1.142 djm 587: kex->flags &= ~KEX_INITIAL;
1.102 markus 588: sshbuf_reset(kex->peer);
589: /* sshbuf_reset(kex->my); */
1.26 markus 590: kex->flags &= ~KEX_INIT_SENT;
1.91 djm 591: free(kex->name);
1.32 markus 592: kex->name = NULL;
1.102 markus 593: return 0;
1.26 markus 594: }
1.1 markus 595:
1.102 markus 596: int
597: kex_send_kexinit(struct ssh *ssh)
1.26 markus 598: {
1.49 markus 599: u_char *cookie;
1.102 markus 600: struct kex *kex = ssh->kex;
601: int r;
1.49 markus 602:
1.152 djm 603: if (kex == NULL) {
1.161 djm 604: error_f("no kex");
1.102 markus 605: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 606: }
1.102 markus 607: if (kex->flags & KEX_INIT_SENT)
608: return 0;
1.30 markus 609: kex->done = 0;
1.49 markus 610:
611: /* generate a random cookie */
1.152 djm 612: if (sshbuf_len(kex->my) < KEX_COOKIE_LEN) {
1.160 djm 613: error_f("bad kex length: %zu < %d",
1.152 djm 614: sshbuf_len(kex->my), KEX_COOKIE_LEN);
1.102 markus 615: return SSH_ERR_INVALID_FORMAT;
1.152 djm 616: }
617: if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL) {
1.160 djm 618: error_f("buffer error");
1.102 markus 619: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 620: }
1.102 markus 621: arc4random_buf(cookie, KEX_COOKIE_LEN);
622:
623: if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
624: (r = sshpkt_putb(ssh, kex->my)) != 0 ||
1.152 djm 625: (r = sshpkt_send(ssh)) != 0) {
1.160 djm 626: error_fr(r, "compose reply");
1.102 markus 627: return r;
1.152 djm 628: }
1.26 markus 629: debug("SSH2_MSG_KEXINIT sent");
630: kex->flags |= KEX_INIT_SENT;
1.102 markus 631: return 0;
1.1 markus 632: }
633:
1.101 markus 634: int
1.133 markus 635: kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
1.11 provos 636: {
1.102 markus 637: struct kex *kex = ssh->kex;
638: const u_char *ptr;
1.100 markus 639: u_int i;
640: size_t dlen;
1.102 markus 641: int r;
1.11 provos 642:
1.26 markus 643: debug("SSH2_MSG_KEXINIT received");
1.152 djm 644: if (kex == NULL) {
1.161 djm 645: error_f("no kex");
1.152 djm 646: return SSH_ERR_INTERNAL_ERROR;
647: }
1.127 markus 648: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, NULL);
1.102 markus 649: ptr = sshpkt_ptr(ssh, &dlen);
650: if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
651: return r;
1.31 markus 652:
653: /* discard packet */
1.152 djm 654: for (i = 0; i < KEX_COOKIE_LEN; i++) {
655: if ((r = sshpkt_get_u8(ssh, NULL)) != 0) {
1.160 djm 656: error_fr(r, "discard cookie");
1.102 markus 657: return r;
1.152 djm 658: }
659: }
660: for (i = 0; i < PROPOSAL_MAX; i++) {
661: if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
1.160 djm 662: error_fr(r, "discard proposal");
1.102 markus 663: return r;
1.152 djm 664: }
665: }
1.87 djm 666: /*
667: * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
668: * KEX method has the server move first, but a server might be using
669: * a custom method or one that we otherwise don't support. We should
670: * be prepared to remember first_kex_follows here so we can eat a
671: * packet later.
672: * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
673: * for cases where the server *doesn't* go first. I guess we should
674: * ignore it when it is set for these cases, which is what we do now.
675: */
1.102 markus 676: if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
677: (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
678: (r = sshpkt_get_end(ssh)) != 0)
679: return r;
680:
681: if (!(kex->flags & KEX_INIT_SENT))
682: if ((r = kex_send_kexinit(ssh)) != 0)
683: return r;
684: if ((r = kex_choose_conf(ssh)) != 0)
685: return r;
1.19 stevesk 686:
1.102 markus 687: if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
688: return (kex->kex[kex->kex_type])(ssh);
689:
1.160 djm 690: error_f("unknown kex type %u", kex->kex_type);
1.102 markus 691: return SSH_ERR_INTERNAL_ERROR;
692: }
693:
1.143 djm 694: struct kex *
695: kex_new(void)
1.102 markus 696: {
697: struct kex *kex;
698:
1.143 djm 699: if ((kex = calloc(1, sizeof(*kex))) == NULL ||
700: (kex->peer = sshbuf_new()) == NULL ||
701: (kex->my = sshbuf_new()) == NULL ||
702: (kex->client_version = sshbuf_new()) == NULL ||
1.165 djm 703: (kex->server_version = sshbuf_new()) == NULL ||
704: (kex->session_id = sshbuf_new()) == NULL) {
1.143 djm 705: kex_free(kex);
706: return NULL;
1.102 markus 707: }
1.143 djm 708: return kex;
1.26 markus 709: }
1.11 provos 710:
1.100 markus 711: void
712: kex_free_newkeys(struct newkeys *newkeys)
713: {
714: if (newkeys == NULL)
715: return;
716: if (newkeys->enc.key) {
717: explicit_bzero(newkeys->enc.key, newkeys->enc.key_len);
718: free(newkeys->enc.key);
719: newkeys->enc.key = NULL;
720: }
721: if (newkeys->enc.iv) {
1.111 djm 722: explicit_bzero(newkeys->enc.iv, newkeys->enc.iv_len);
1.100 markus 723: free(newkeys->enc.iv);
724: newkeys->enc.iv = NULL;
725: }
726: free(newkeys->enc.name);
727: explicit_bzero(&newkeys->enc, sizeof(newkeys->enc));
728: free(newkeys->comp.name);
729: explicit_bzero(&newkeys->comp, sizeof(newkeys->comp));
730: mac_clear(&newkeys->mac);
731: if (newkeys->mac.key) {
732: explicit_bzero(newkeys->mac.key, newkeys->mac.key_len);
733: free(newkeys->mac.key);
734: newkeys->mac.key = NULL;
735: }
736: free(newkeys->mac.name);
737: explicit_bzero(&newkeys->mac, sizeof(newkeys->mac));
1.157 jsg 738: freezero(newkeys, sizeof(*newkeys));
1.100 markus 739: }
740:
1.102 markus 741: void
742: kex_free(struct kex *kex)
1.26 markus 743: {
1.102 markus 744: u_int mode;
1.11 provos 745:
1.143 djm 746: if (kex == NULL)
747: return;
748:
1.102 markus 749: #ifdef WITH_OPENSSL
1.136 jsing 750: DH_free(kex->dh);
751: EC_KEY_free(kex->ec_client_key);
1.102 markus 752: #endif
753: for (mode = 0; mode < MODE_MAX; mode++) {
754: kex_free_newkeys(kex->newkeys[mode]);
755: kex->newkeys[mode] = NULL;
1.100 markus 756: }
1.102 markus 757: sshbuf_free(kex->peer);
758: sshbuf_free(kex->my);
1.143 djm 759: sshbuf_free(kex->client_version);
760: sshbuf_free(kex->server_version);
1.149 djm 761: sshbuf_free(kex->client_pub);
1.165 djm 762: sshbuf_free(kex->session_id);
1.169 djm 763: sshbuf_free(kex->initial_sig);
764: sshkey_free(kex->initial_hostkey);
1.107 djm 765: free(kex->failed_choice);
1.113 markus 766: free(kex->hostkey_alg);
767: free(kex->name);
1.102 markus 768: free(kex);
1.11 provos 769: }
770:
1.102 markus 771: int
1.143 djm 772: kex_ready(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
773: {
774: int r;
775:
776: if ((r = kex_prop2buf(ssh->kex->my, proposal)) != 0)
777: return r;
778: ssh->kex->flags = KEX_INITIAL;
779: kex_reset_dispatch(ssh);
780: ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
781: return 0;
782: }
783:
784: int
1.102 markus 785: kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
1.1 markus 786: {
1.102 markus 787: int r;
1.1 markus 788:
1.143 djm 789: if ((r = kex_ready(ssh, proposal)) != 0)
1.102 markus 790: return r;
791: if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
792: kex_free(ssh->kex);
793: ssh->kex = NULL;
794: return r;
1.1 markus 795: }
1.102 markus 796: return 0;
1.117 djm 797: }
798:
799: /*
800: * Request key re-exchange, returns 0 on success or a ssherr.h error
801: * code otherwise. Must not be called if KEX is incomplete or in-progress.
802: */
803: int
804: kex_start_rekex(struct ssh *ssh)
805: {
806: if (ssh->kex == NULL) {
1.160 djm 807: error_f("no kex");
1.117 djm 808: return SSH_ERR_INTERNAL_ERROR;
809: }
810: if (ssh->kex->done == 0) {
1.160 djm 811: error_f("requested twice");
1.117 djm 812: return SSH_ERR_INTERNAL_ERROR;
813: }
814: ssh->kex->done = 0;
815: return kex_send_kexinit(ssh);
1.1 markus 816: }
817:
1.102 markus 818: static int
819: choose_enc(struct sshenc *enc, char *client, char *server)
1.1 markus 820: {
1.23 markus 821: char *name = match_list(client, server, NULL);
1.102 markus 822:
1.1 markus 823: if (name == NULL)
1.102 markus 824: return SSH_ERR_NO_CIPHER_ALG_MATCH;
1.129 dtucker 825: if ((enc->cipher = cipher_by_name(name)) == NULL) {
1.160 djm 826: error_f("unsupported cipher %s", name);
1.129 dtucker 827: free(name);
1.102 markus 828: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 829: }
1.1 markus 830: enc->name = name;
831: enc->enabled = 0;
832: enc->iv = NULL;
1.88 markus 833: enc->iv_len = cipher_ivlen(enc->cipher);
1.1 markus 834: enc->key = NULL;
1.45 markus 835: enc->key_len = cipher_keylen(enc->cipher);
836: enc->block_size = cipher_blocksize(enc->cipher);
1.102 markus 837: return 0;
1.1 markus 838: }
1.69 deraadt 839:
1.102 markus 840: static int
841: choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
1.1 markus 842: {
1.23 markus 843: char *name = match_list(client, server, NULL);
1.102 markus 844:
1.1 markus 845: if (name == NULL)
1.102 markus 846: return SSH_ERR_NO_MAC_ALG_MATCH;
1.129 dtucker 847: if (mac_setup(mac, name) < 0) {
1.160 djm 848: error_f("unsupported MAC %s", name);
1.129 dtucker 849: free(name);
1.102 markus 850: return SSH_ERR_INTERNAL_ERROR;
1.129 dtucker 851: }
1.1 markus 852: mac->name = name;
853: mac->key = NULL;
854: mac->enabled = 0;
1.102 markus 855: return 0;
1.1 markus 856: }
1.69 deraadt 857:
1.102 markus 858: static int
859: choose_comp(struct sshcomp *comp, char *client, char *server)
1.1 markus 860: {
1.23 markus 861: char *name = match_list(client, server, NULL);
1.102 markus 862:
1.1 markus 863: if (name == NULL)
1.102 markus 864: return SSH_ERR_NO_COMPRESS_ALG_MATCH;
1.156 dtucker 865: #ifdef WITH_ZLIB
1.64 markus 866: if (strcmp(name, "zlib@openssh.com") == 0) {
1.141 sf 867: comp->type = COMP_DELAYED;
868: } else if (strcmp(name, "zlib") == 0) {
1.140 sf 869: comp->type = COMP_ZLIB;
1.156 dtucker 870: } else
871: #endif /* WITH_ZLIB */
872: if (strcmp(name, "none") == 0) {
1.64 markus 873: comp->type = COMP_NONE;
1.1 markus 874: } else {
1.160 djm 875: error_f("unsupported compression scheme %s", name);
1.129 dtucker 876: free(name);
1.102 markus 877: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 878: }
879: comp->name = name;
1.102 markus 880: return 0;
1.1 markus 881: }
1.69 deraadt 882:
1.102 markus 883: static int
884: choose_kex(struct kex *k, char *client, char *server)
1.1 markus 885: {
1.89 djm 886: const struct kexalg *kexalg;
887:
1.23 markus 888: k->name = match_list(client, server, NULL);
1.102 markus 889:
1.110 djm 890: debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
1.1 markus 891: if (k->name == NULL)
1.102 markus 892: return SSH_ERR_NO_KEX_ALG_MATCH;
1.152 djm 893: if ((kexalg = kex_alg_by_name(k->name)) == NULL) {
1.160 djm 894: error_f("unsupported KEX method %s", k->name);
1.102 markus 895: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 896: }
1.89 djm 897: k->kex_type = kexalg->type;
1.94 djm 898: k->hash_alg = kexalg->hash_alg;
1.89 djm 899: k->ec_nid = kexalg->ec_nid;
1.102 markus 900: return 0;
1.1 markus 901: }
1.65 djm 902:
1.102 markus 903: static int
904: choose_hostkeyalg(struct kex *k, char *client, char *server)
1.1 markus 905: {
1.162 djm 906: free(k->hostkey_alg);
1.113 markus 907: k->hostkey_alg = match_list(client, server, NULL);
1.102 markus 908:
1.110 djm 909: debug("kex: host key algorithm: %s",
1.113 markus 910: k->hostkey_alg ? k->hostkey_alg : "(no match)");
911: if (k->hostkey_alg == NULL)
1.102 markus 912: return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
1.113 markus 913: k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
1.152 djm 914: if (k->hostkey_type == KEY_UNSPEC) {
1.160 djm 915: error_f("unsupported hostkey algorithm %s", k->hostkey_alg);
1.102 markus 916: return SSH_ERR_INTERNAL_ERROR;
1.152 djm 917: }
1.113 markus 918: k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
1.102 markus 919: return 0;
1.1 markus 920: }
921:
1.56 djm 922: static int
1.53 markus 923: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
924: {
925: static int check[] = {
926: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
927: };
928: int *idx;
929: char *p;
930:
931: for (idx = &check[0]; *idx != -1; idx++) {
932: if ((p = strchr(my[*idx], ',')) != NULL)
933: *p = '\0';
934: if ((p = strchr(peer[*idx], ',')) != NULL)
935: *p = '\0';
936: if (strcmp(my[*idx], peer[*idx]) != 0) {
937: debug2("proposal mismatch: my %s peer %s",
938: my[*idx], peer[*idx]);
939: return (0);
940: }
941: }
942: debug2("proposals match");
943: return (1);
944: }
945:
1.171 djm 946: /* returns non-zero if proposal contains any algorithm from algs */
947: static int
948: has_any_alg(const char *proposal, const char *algs)
949: {
950: char *cp;
951:
952: if ((cp = match_list(proposal, algs, NULL)) == NULL)
953: return 0;
954: free(cp);
955: return 1;
956: }
957:
1.102 markus 958: static int
959: kex_choose_conf(struct ssh *ssh)
1.1 markus 960: {
1.102 markus 961: struct kex *kex = ssh->kex;
962: struct newkeys *newkeys;
963: char **my = NULL, **peer = NULL;
1.26 markus 964: char **cprop, **sprop;
1.27 markus 965: int nenc, nmac, ncomp;
1.96 dtucker 966: u_int mode, ctos, need, dh_need, authlen;
1.102 markus 967: int r, first_kex_follows;
1.1 markus 968:
1.110 djm 969: debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
970: if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
971: goto out;
972: debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
973: if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
1.102 markus 974: goto out;
1.26 markus 975:
1.27 markus 976: if (kex->server) {
1.26 markus 977: cprop=peer;
978: sprop=my;
979: } else {
980: cprop=my;
981: sprop=peer;
1.113 markus 982: }
983:
984: /* Check whether client supports ext_info_c */
1.142 djm 985: if (kex->server && (kex->flags & KEX_INITIAL)) {
1.113 markus 986: char *ext;
987:
988: ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
1.119 markus 989: kex->ext_info_c = (ext != NULL);
990: free(ext);
1.171 djm 991: }
992:
993: /* Check whether client supports rsa-sha2 algorithms */
994: if (kex->server && (kex->flags & KEX_INITIAL)) {
995: if (has_any_alg(peer[PROPOSAL_SERVER_HOST_KEY_ALGS],
996: "rsa-sha2-256,rsa-sha2-256-cert-v01@openssh.com"))
997: kex->flags |= KEX_RSA_SHA2_256_SUPPORTED;
998: if (has_any_alg(peer[PROPOSAL_SERVER_HOST_KEY_ALGS],
999: "rsa-sha2-512,rsa-sha2-512-cert-v01@openssh.com"))
1000: kex->flags |= KEX_RSA_SHA2_512_SUPPORTED;
1.26 markus 1001: }
1.1 markus 1002:
1.30 markus 1003: /* Algorithm Negotiation */
1.110 djm 1004: if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
1005: sprop[PROPOSAL_KEX_ALGS])) != 0) {
1006: kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
1007: peer[PROPOSAL_KEX_ALGS] = NULL;
1008: goto out;
1009: }
1010: if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
1011: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
1012: kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
1013: peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
1014: goto out;
1015: }
1.1 markus 1016: for (mode = 0; mode < MODE_MAX; mode++) {
1.102 markus 1017: if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
1018: r = SSH_ERR_ALLOC_FAIL;
1019: goto out;
1020: }
1.30 markus 1021: kex->newkeys[mode] = newkeys;
1.78 djm 1022: ctos = (!kex->server && mode == MODE_OUT) ||
1023: (kex->server && mode == MODE_IN);
1.1 markus 1024: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
1025: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
1026: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.102 markus 1027: if ((r = choose_enc(&newkeys->enc, cprop[nenc],
1.107 djm 1028: sprop[nenc])) != 0) {
1029: kex->failed_choice = peer[nenc];
1030: peer[nenc] = NULL;
1.102 markus 1031: goto out;
1.107 djm 1032: }
1.102 markus 1033: authlen = cipher_authlen(newkeys->enc.cipher);
1.88 markus 1034: /* ignore mac for authenticated encryption */
1.102 markus 1035: if (authlen == 0 &&
1036: (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
1.107 djm 1037: sprop[nmac])) != 0) {
1038: kex->failed_choice = peer[nmac];
1039: peer[nmac] = NULL;
1.102 markus 1040: goto out;
1.107 djm 1041: }
1.102 markus 1042: if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
1.107 djm 1043: sprop[ncomp])) != 0) {
1044: kex->failed_choice = peer[ncomp];
1045: peer[ncomp] = NULL;
1.102 markus 1046: goto out;
1.107 djm 1047: }
1.110 djm 1048: debug("kex: %s cipher: %s MAC: %s compression: %s",
1.1 markus 1049: ctos ? "client->server" : "server->client",
1.27 markus 1050: newkeys->enc.name,
1.88 markus 1051: authlen == 0 ? newkeys->mac.name : "<implicit>",
1.27 markus 1052: newkeys->comp.name);
1.107 djm 1053: }
1.96 dtucker 1054: need = dh_need = 0;
1.1 markus 1055: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 1056: newkeys = kex->newkeys[mode];
1.120 deraadt 1057: need = MAXIMUM(need, newkeys->enc.key_len);
1058: need = MAXIMUM(need, newkeys->enc.block_size);
1059: need = MAXIMUM(need, newkeys->enc.iv_len);
1060: need = MAXIMUM(need, newkeys->mac.key_len);
1061: dh_need = MAXIMUM(dh_need, cipher_seclen(newkeys->enc.cipher));
1062: dh_need = MAXIMUM(dh_need, newkeys->enc.block_size);
1063: dh_need = MAXIMUM(dh_need, newkeys->enc.iv_len);
1064: dh_need = MAXIMUM(dh_need, newkeys->mac.key_len);
1.1 markus 1065: }
1.7 markus 1066: /* XXX need runden? */
1.27 markus 1067: kex->we_need = need;
1.96 dtucker 1068: kex->dh_need = dh_need;
1.53 markus 1069:
1070: /* ignore the next message if the proposals do not match */
1.135 djm 1071: if (first_kex_follows && !proposals_match(my, peer))
1.102 markus 1072: ssh->dispatch_skip_packets = 1;
1073: r = 0;
1074: out:
1.26 markus 1075: kex_prop_free(my);
1076: kex_prop_free(peer);
1.102 markus 1077: return r;
1.26 markus 1078: }
1079:
1.102 markus 1080: static int
1081: derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
1082: const struct sshbuf *shared_secret, u_char **keyp)
1.26 markus 1083: {
1.102 markus 1084: struct kex *kex = ssh->kex;
1085: struct ssh_digest_ctx *hashctx = NULL;
1.26 markus 1086: char c = id;
1.61 djm 1087: u_int have;
1.94 djm 1088: size_t mdsz;
1.61 djm 1089: u_char *digest;
1.102 markus 1090: int r;
1.62 djm 1091:
1.94 djm 1092: if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
1.102 markus 1093: return SSH_ERR_INVALID_ARGUMENT;
1.120 deraadt 1094: if ((digest = calloc(1, ROUNDUP(need, mdsz))) == NULL) {
1.102 markus 1095: r = SSH_ERR_ALLOC_FAIL;
1096: goto out;
1097: }
1.26 markus 1098:
1.30 markus 1099: /* K1 = HASH(K || H || "A" || session_id) */
1.102 markus 1100: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1101: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 1102: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1103: ssh_digest_update(hashctx, &c, 1) != 0 ||
1.165 djm 1104: ssh_digest_update_buffer(hashctx, kex->session_id) != 0 ||
1.102 markus 1105: ssh_digest_final(hashctx, digest, mdsz) != 0) {
1106: r = SSH_ERR_LIBCRYPTO_ERROR;
1.160 djm 1107: error_f("KEX hash failed");
1.102 markus 1108: goto out;
1109: }
1.94 djm 1110: ssh_digest_free(hashctx);
1.102 markus 1111: hashctx = NULL;
1.26 markus 1112:
1.30 markus 1113: /*
1114: * expand key:
1115: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
1116: * Key = K1 || K2 || ... || Kn
1117: */
1.26 markus 1118: for (have = mdsz; need > have; have += mdsz) {
1.102 markus 1119: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
1120: ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
1.94 djm 1121: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
1.102 markus 1122: ssh_digest_update(hashctx, digest, have) != 0 ||
1123: ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
1.160 djm 1124: error_f("KDF failed");
1.102 markus 1125: r = SSH_ERR_LIBCRYPTO_ERROR;
1126: goto out;
1127: }
1.94 djm 1128: ssh_digest_free(hashctx);
1.102 markus 1129: hashctx = NULL;
1.26 markus 1130: }
1131: #ifdef DEBUG_KEX
1132: fprintf(stderr, "key '%c'== ", c);
1133: dump_digest("key", digest, need);
1134: #endif
1.102 markus 1135: *keyp = digest;
1136: digest = NULL;
1137: r = 0;
1138: out:
1.114 mmcc 1139: free(digest);
1.102 markus 1140: ssh_digest_free(hashctx);
1141: return r;
1.1 markus 1142: }
1143:
1.23 markus 1144: #define NKEYS 6
1.102 markus 1145: int
1146: kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
1147: const struct sshbuf *shared_secret)
1.1 markus 1148: {
1.102 markus 1149: struct kex *kex = ssh->kex;
1.15 markus 1150: u_char *keys[NKEYS];
1.102 markus 1151: u_int i, j, mode, ctos;
1152: int r;
1.1 markus 1153:
1.144 djm 1154: /* save initial hash as session id */
1.165 djm 1155: if ((kex->flags & KEX_INITIAL) != 0) {
1.166 djm 1156: if (sshbuf_len(kex->session_id) != 0) {
1157: error_f("already have session ID at kex");
1158: return SSH_ERR_INTERNAL_ERROR;
1159: }
1.165 djm 1160: if ((r = sshbuf_put(kex->session_id, hash, hashlen)) != 0)
1161: return r;
1162: } else if (sshbuf_len(kex->session_id) == 0) {
1163: error_f("no session ID in rekex");
1.166 djm 1164: return SSH_ERR_INTERNAL_ERROR;
1.144 djm 1165: }
1.65 djm 1166: for (i = 0; i < NKEYS; i++) {
1.102 markus 1167: if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
1168: shared_secret, &keys[i])) != 0) {
1169: for (j = 0; j < i; j++)
1170: free(keys[j]);
1171: return r;
1172: }
1.65 djm 1173: }
1.1 markus 1174: for (mode = 0; mode < MODE_MAX; mode++) {
1.69 deraadt 1175: ctos = (!kex->server && mode == MODE_OUT) ||
1176: (kex->server && mode == MODE_IN);
1.100 markus 1177: kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
1178: kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
1179: kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 1180: }
1.102 markus 1181: return 0;
1.95 djm 1182: }
1.57 djm 1183:
1.145 djm 1184: int
1.150 djm 1185: kex_load_hostkey(struct ssh *ssh, struct sshkey **prvp, struct sshkey **pubp)
1.145 djm 1186: {
1187: struct kex *kex = ssh->kex;
1188:
1189: *pubp = NULL;
1190: *prvp = NULL;
1191: if (kex->load_host_public_key == NULL ||
1.152 djm 1192: kex->load_host_private_key == NULL) {
1.160 djm 1193: error_f("missing hostkey loader");
1.145 djm 1194: return SSH_ERR_INVALID_ARGUMENT;
1.152 djm 1195: }
1.145 djm 1196: *pubp = kex->load_host_public_key(kex->hostkey_type,
1197: kex->hostkey_nid, ssh);
1198: *prvp = kex->load_host_private_key(kex->hostkey_type,
1199: kex->hostkey_nid, ssh);
1200: if (*pubp == NULL)
1201: return SSH_ERR_NO_HOSTKEY_LOADED;
1.146 djm 1202: return 0;
1203: }
1204:
1205: int
1206: kex_verify_host_key(struct ssh *ssh, struct sshkey *server_host_key)
1207: {
1208: struct kex *kex = ssh->kex;
1209:
1.152 djm 1210: if (kex->verify_host_key == NULL) {
1.160 djm 1211: error_f("missing hostkey verifier");
1.146 djm 1212: return SSH_ERR_INVALID_ARGUMENT;
1.152 djm 1213: }
1.146 djm 1214: if (server_host_key->type != kex->hostkey_type ||
1215: (kex->hostkey_type == KEY_ECDSA &&
1216: server_host_key->ecdsa_nid != kex->hostkey_nid))
1217: return SSH_ERR_KEY_TYPE_MISMATCH;
1218: if (kex->verify_host_key(server_host_key, ssh) == -1)
1219: return SSH_ERR_SIGNATURE_INVALID;
1.145 djm 1220: return 0;
1221: }
1.26 markus 1222:
1.84 djm 1223: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1.26 markus 1224: void
1.147 djm 1225: dump_digest(const char *msg, const u_char *digest, int len)
1.26 markus 1226: {
1227: fprintf(stderr, "%s\n", msg);
1.102 markus 1228: sshbuf_dump_data(digest, len, stderr);
1.26 markus 1229: }
1230: #endif
1.143 djm 1231:
1232: /*
1233: * Send a plaintext error message to the peer, suffixed by \r\n.
1234: * Only used during banner exchange, and there only for the server.
1235: */
1236: static void
1237: send_error(struct ssh *ssh, char *msg)
1238: {
1239: char *crnl = "\r\n";
1240:
1241: if (!ssh->kex->server)
1242: return;
1243:
1244: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1245: msg, strlen(msg)) != strlen(msg) ||
1246: atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1247: crnl, strlen(crnl)) != strlen(crnl))
1.160 djm 1248: error_f("write: %.100s", strerror(errno));
1.143 djm 1249: }
1250:
1251: /*
1252: * Sends our identification string and waits for the peer's. Will block for
1253: * up to timeout_ms (or indefinitely if timeout_ms <= 0).
1254: * Returns on 0 success or a ssherr.h code on failure.
1255: */
1256: int
1257: kex_exchange_identification(struct ssh *ssh, int timeout_ms,
1258: const char *version_addendum)
1259: {
1.158 djm 1260: int remote_major, remote_minor, mismatch, oerrno = 0;
1.173 dtucker 1261: size_t len, n;
1.143 djm 1262: int r, expect_nl;
1263: u_char c;
1264: struct sshbuf *our_version = ssh->kex->server ?
1265: ssh->kex->server_version : ssh->kex->client_version;
1266: struct sshbuf *peer_version = ssh->kex->server ?
1267: ssh->kex->client_version : ssh->kex->server_version;
1268: char *our_version_string = NULL, *peer_version_string = NULL;
1269: char *cp, *remote_version = NULL;
1270:
1271: /* Prepare and send our banner */
1272: sshbuf_reset(our_version);
1273: if (version_addendum != NULL && *version_addendum == '\0')
1274: version_addendum = NULL;
1275: if ((r = sshbuf_putf(our_version, "SSH-%d.%d-%.100s%s%s\r\n",
1.168 djm 1276: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
1.143 djm 1277: version_addendum == NULL ? "" : " ",
1278: version_addendum == NULL ? "" : version_addendum)) != 0) {
1.158 djm 1279: oerrno = errno;
1.160 djm 1280: error_fr(r, "sshbuf_putf");
1.143 djm 1281: goto out;
1282: }
1283:
1284: if (atomicio(vwrite, ssh_packet_get_connection_out(ssh),
1285: sshbuf_mutable_ptr(our_version),
1286: sshbuf_len(our_version)) != sshbuf_len(our_version)) {
1.158 djm 1287: oerrno = errno;
1.160 djm 1288: debug_f("write: %.100s", strerror(errno));
1.143 djm 1289: r = SSH_ERR_SYSTEM_ERROR;
1290: goto out;
1291: }
1292: if ((r = sshbuf_consume_end(our_version, 2)) != 0) { /* trim \r\n */
1.158 djm 1293: oerrno = errno;
1.160 djm 1294: error_fr(r, "sshbuf_consume_end");
1.143 djm 1295: goto out;
1296: }
1297: our_version_string = sshbuf_dup_string(our_version);
1298: if (our_version_string == NULL) {
1.160 djm 1299: error_f("sshbuf_dup_string failed");
1.143 djm 1300: r = SSH_ERR_ALLOC_FAIL;
1301: goto out;
1302: }
1303: debug("Local version string %.100s", our_version_string);
1304:
1305: /* Read other side's version identification. */
1306: for (n = 0; ; n++) {
1307: if (n >= SSH_MAX_PRE_BANNER_LINES) {
1308: send_error(ssh, "No SSH identification string "
1309: "received.");
1.160 djm 1310: error_f("No SSH version received in first %u lines "
1311: "from server", SSH_MAX_PRE_BANNER_LINES);
1.143 djm 1312: r = SSH_ERR_INVALID_FORMAT;
1313: goto out;
1314: }
1315: sshbuf_reset(peer_version);
1316: expect_nl = 0;
1.173 dtucker 1317: for (;;) {
1.143 djm 1318: if (timeout_ms > 0) {
1319: r = waitrfd(ssh_packet_get_connection_in(ssh),
1.179 ! djm 1320: &timeout_ms, NULL);
1.143 djm 1321: if (r == -1 && errno == ETIMEDOUT) {
1322: send_error(ssh, "Timed out waiting "
1323: "for SSH identification string.");
1324: error("Connection timed out during "
1325: "banner exchange");
1326: r = SSH_ERR_CONN_TIMEOUT;
1327: goto out;
1328: } else if (r == -1) {
1.158 djm 1329: oerrno = errno;
1.160 djm 1330: error_f("%s", strerror(errno));
1.143 djm 1331: r = SSH_ERR_SYSTEM_ERROR;
1332: goto out;
1333: }
1334: }
1335:
1336: len = atomicio(read, ssh_packet_get_connection_in(ssh),
1337: &c, 1);
1338: if (len != 1 && errno == EPIPE) {
1.160 djm 1339: error_f("Connection closed by remote host");
1.143 djm 1340: r = SSH_ERR_CONN_CLOSED;
1341: goto out;
1342: } else if (len != 1) {
1.158 djm 1343: oerrno = errno;
1.160 djm 1344: error_f("read: %.100s", strerror(errno));
1.143 djm 1345: r = SSH_ERR_SYSTEM_ERROR;
1346: goto out;
1347: }
1348: if (c == '\r') {
1349: expect_nl = 1;
1350: continue;
1351: }
1352: if (c == '\n')
1353: break;
1354: if (c == '\0' || expect_nl) {
1.160 djm 1355: error_f("banner line contains invalid "
1356: "characters");
1.143 djm 1357: goto invalid;
1358: }
1359: if ((r = sshbuf_put_u8(peer_version, c)) != 0) {
1.158 djm 1360: oerrno = errno;
1.160 djm 1361: error_fr(r, "sshbuf_put");
1.143 djm 1362: goto out;
1363: }
1364: if (sshbuf_len(peer_version) > SSH_MAX_BANNER_LEN) {
1.160 djm 1365: error_f("banner line too long");
1.143 djm 1366: goto invalid;
1367: }
1368: }
1369: /* Is this an actual protocol banner? */
1370: if (sshbuf_len(peer_version) > 4 &&
1371: memcmp(sshbuf_ptr(peer_version), "SSH-", 4) == 0)
1372: break;
1373: /* If not, then just log the line and continue */
1374: if ((cp = sshbuf_dup_string(peer_version)) == NULL) {
1.160 djm 1375: error_f("sshbuf_dup_string failed");
1.143 djm 1376: r = SSH_ERR_ALLOC_FAIL;
1377: goto out;
1378: }
1379: /* Do not accept lines before the SSH ident from a client */
1380: if (ssh->kex->server) {
1.160 djm 1381: error_f("client sent invalid protocol identifier "
1382: "\"%.256s\"", cp);
1.143 djm 1383: free(cp);
1384: goto invalid;
1385: }
1.160 djm 1386: debug_f("banner line %zu: %s", n, cp);
1.143 djm 1387: free(cp);
1388: }
1389: peer_version_string = sshbuf_dup_string(peer_version);
1390: if (peer_version_string == NULL)
1.175 dtucker 1391: fatal_f("sshbuf_dup_string failed");
1.143 djm 1392: /* XXX must be same size for sscanf */
1393: if ((remote_version = calloc(1, sshbuf_len(peer_version))) == NULL) {
1.160 djm 1394: error_f("calloc failed");
1.143 djm 1395: r = SSH_ERR_ALLOC_FAIL;
1396: goto out;
1397: }
1398:
1399: /*
1400: * Check that the versions match. In future this might accept
1401: * several versions and set appropriate flags to handle them.
1402: */
1403: if (sscanf(peer_version_string, "SSH-%d.%d-%[^\n]\n",
1404: &remote_major, &remote_minor, remote_version) != 3) {
1405: error("Bad remote protocol version identification: '%.100s'",
1406: peer_version_string);
1407: invalid:
1408: send_error(ssh, "Invalid SSH identification string.");
1409: r = SSH_ERR_INVALID_FORMAT;
1410: goto out;
1411: }
1412: debug("Remote protocol version %d.%d, remote software version %.100s",
1413: remote_major, remote_minor, remote_version);
1.164 djm 1414: compat_banner(ssh, remote_version);
1.143 djm 1415:
1416: mismatch = 0;
1417: switch (remote_major) {
1418: case 2:
1419: break;
1420: case 1:
1421: if (remote_minor != 99)
1422: mismatch = 1;
1423: break;
1424: default:
1425: mismatch = 1;
1426: break;
1427: }
1428: if (mismatch) {
1429: error("Protocol major versions differ: %d vs. %d",
1430: PROTOCOL_MAJOR_2, remote_major);
1431: send_error(ssh, "Protocol major versions differ.");
1432: r = SSH_ERR_NO_PROTOCOL_VERSION;
1433: goto out;
1434: }
1435:
1436: if (ssh->kex->server && (ssh->compat & SSH_BUG_PROBE) != 0) {
1437: logit("probed from %s port %d with %s. Don't panic.",
1438: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1439: peer_version_string);
1440: r = SSH_ERR_CONN_CLOSED; /* XXX */
1441: goto out;
1442: }
1443: if (ssh->kex->server && (ssh->compat & SSH_BUG_SCANNER) != 0) {
1444: logit("scanned from %s port %d with %s. Don't panic.",
1445: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
1446: peer_version_string);
1447: r = SSH_ERR_CONN_CLOSED; /* XXX */
1448: goto out;
1449: }
1450: /* success */
1451: r = 0;
1452: out:
1453: free(our_version_string);
1454: free(peer_version_string);
1455: free(remote_version);
1.158 djm 1456: if (r == SSH_ERR_SYSTEM_ERROR)
1457: errno = oerrno;
1.143 djm 1458: return r;
1459: }
1460:
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