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djm@openbsd.org523463a2015-02-16 22:13:32 +00001/* $OpenBSD: ssh_api.c,v 1.4 2015/02/16 22:13:32 djm Exp $ */
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +00002/*
3 * Copyright (c) 2012 Markus Friedl. All rights reserved.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#include "includes.h"
19
20#include "ssh1.h" /* For SSH_MSG_NONE */
21#include "ssh_api.h"
22#include "compat.h"
23#include "log.h"
24#include "authfile.h"
25#include "sshkey.h"
26#include "misc.h"
27#include "ssh1.h"
28#include "ssh2.h"
29#include "version.h"
30#include "myproposal.h"
31#include "ssherr.h"
32#include "sshbuf.h"
33
34#include <string.h>
35
36int _ssh_exchange_banner(struct ssh *);
37int _ssh_send_banner(struct ssh *, char **);
38int _ssh_read_banner(struct ssh *, char **);
39int _ssh_order_hostkeyalgs(struct ssh *);
40int _ssh_verify_host_key(struct sshkey *, struct ssh *);
djm@openbsd.org5104db72015-01-26 06:10:03 +000041struct sshkey *_ssh_host_public_key(int, int, struct ssh *);
42struct sshkey *_ssh_host_private_key(int, int, struct ssh *);
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +000043int _ssh_host_key_sign(struct sshkey *, struct sshkey *, u_char **,
djm@openbsd.org523463a2015-02-16 22:13:32 +000044 size_t *, const u_char *, size_t, u_int);
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +000045
46/*
47 * stubs for the server side implementation of kex.
48 * disable privsep so our stubs will never be called.
49 */
50int use_privsep = 0;
51int mm_sshkey_sign(struct sshkey *, u_char **, u_int *,
52 u_char *, u_int, u_int);
53DH *mm_choose_dh(int, int, int);
54
55/* Define these two variables here so that they are part of the library */
56u_char *session_id2 = NULL;
57u_int session_id2_len = 0;
58
59int
60mm_sshkey_sign(struct sshkey *key, u_char **sigp, u_int *lenp,
61 u_char *data, u_int datalen, u_int compat)
62{
63 return (-1);
64}
65
66DH *
67mm_choose_dh(int min, int nbits, int max)
68{
69 return (NULL);
70}
71
72/* API */
73
74int
75ssh_init(struct ssh **sshp, int is_server, struct kex_params *kex_params)
76{
77 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
78 struct ssh *ssh;
79 char **proposal;
80 static int called;
81 int r;
82
83 if (!called) {
Damien Miller773dda22015-01-30 23:10:17 +110084#ifdef WITH_OPENSSL
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +000085 OpenSSL_add_all_algorithms();
Damien Miller773dda22015-01-30 23:10:17 +110086#endif /* WITH_OPENSSL */
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +000087 called = 1;
88 }
89
djm@openbsd.org4509b5d2015-01-30 01:13:33 +000090 if ((ssh = ssh_packet_set_connection(NULL, -1, -1)) == NULL)
91 return SSH_ERR_ALLOC_FAIL;
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +000092 if (is_server)
93 ssh_packet_set_server(ssh);
94
95 /* Initialize key exchange */
96 proposal = kex_params ? kex_params->proposal : myproposal;
97 if ((r = kex_new(ssh, proposal, &ssh->kex)) != 0) {
98 ssh_free(ssh);
99 return r;
100 }
101 ssh->kex->server = is_server;
102 if (is_server) {
103#ifdef WITH_OPENSSL
104 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
105 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
106 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
107 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
Darren Tuckerf2004cd2015-02-23 05:04:21 +1100108# ifdef OPENSSL_HAS_ECC
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000109 ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
Darren Tuckerf2004cd2015-02-23 05:04:21 +1100110# endif
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000111#endif /* WITH_OPENSSL */
112 ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_server;
113 ssh->kex->load_host_public_key=&_ssh_host_public_key;
114 ssh->kex->load_host_private_key=&_ssh_host_private_key;
115 ssh->kex->sign=&_ssh_host_key_sign;
116 } else {
117#ifdef WITH_OPENSSL
118 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
119 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
120 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
121 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
Darren Tuckerf2004cd2015-02-23 05:04:21 +1100122# ifdef OPENSSL_HAS_ECC
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000123 ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
Darren Tuckerf2004cd2015-02-23 05:04:21 +1100124# endif
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000125#endif /* WITH_OPENSSL */
126 ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
127 ssh->kex->verify_host_key =&_ssh_verify_host_key;
128 }
129 *sshp = ssh;
130 return 0;
131}
132
133void
134ssh_free(struct ssh *ssh)
135{
136 struct key_entry *k;
137
138 ssh_packet_close(ssh);
139 /*
140 * we've only created the public keys variants in case we
141 * are a acting as a server.
142 */
143 while ((k = TAILQ_FIRST(&ssh->public_keys)) != NULL) {
144 TAILQ_REMOVE(&ssh->public_keys, k, next);
145 if (ssh->kex && ssh->kex->server)
146 sshkey_free(k->key);
147 free(k);
148 }
149 while ((k = TAILQ_FIRST(&ssh->private_keys)) != NULL) {
150 TAILQ_REMOVE(&ssh->private_keys, k, next);
151 free(k);
152 }
153 if (ssh->kex)
154 kex_free(ssh->kex);
155 free(ssh);
156}
157
158void
159ssh_set_app_data(struct ssh *ssh, void *app_data)
160{
161 ssh->app_data = app_data;
162}
163
164void *
165ssh_get_app_data(struct ssh *ssh)
166{
167 return ssh->app_data;
168}
169
170/* Returns < 0 on error, 0 otherwise */
171int
172ssh_add_hostkey(struct ssh *ssh, struct sshkey *key)
173{
174 struct sshkey *pubkey = NULL;
175 struct key_entry *k = NULL, *k_prv = NULL;
176 int r;
177
178 if (ssh->kex->server) {
179 if ((r = sshkey_from_private(key, &pubkey)) != 0)
180 return r;
181 if ((k = malloc(sizeof(*k))) == NULL ||
182 (k_prv = malloc(sizeof(*k_prv))) == NULL) {
183 free(k);
184 sshkey_free(pubkey);
185 return SSH_ERR_ALLOC_FAIL;
186 }
187 k_prv->key = key;
188 TAILQ_INSERT_TAIL(&ssh->private_keys, k_prv, next);
189
190 /* add the public key, too */
191 k->key = pubkey;
192 TAILQ_INSERT_TAIL(&ssh->public_keys, k, next);
193 r = 0;
194 } else {
195 if ((k = malloc(sizeof(*k))) == NULL)
196 return SSH_ERR_ALLOC_FAIL;
197 k->key = key;
198 TAILQ_INSERT_TAIL(&ssh->public_keys, k, next);
199 r = 0;
200 }
201
202 return r;
203}
204
205int
206ssh_set_verify_host_key_callback(struct ssh *ssh,
207 int (*cb)(struct sshkey *, struct ssh *))
208{
209 if (cb == NULL || ssh->kex == NULL)
210 return SSH_ERR_INVALID_ARGUMENT;
211
212 ssh->kex->verify_host_key = cb;
213
214 return 0;
215}
216
217int
218ssh_input_append(struct ssh *ssh, const u_char *data, size_t len)
219{
220 return sshbuf_put(ssh_packet_get_input(ssh), data, len);
221}
222
223int
224ssh_packet_next(struct ssh *ssh, u_char *typep)
225{
226 int r;
227 u_int32_t seqnr;
228 u_char type;
229
230 /*
231 * Try to read a packet. Return SSH_MSG_NONE if no packet or not
232 * enough data.
233 */
234 *typep = SSH_MSG_NONE;
235 if (ssh->kex->client_version_string == NULL ||
236 ssh->kex->server_version_string == NULL)
237 return _ssh_exchange_banner(ssh);
238 /*
239 * If we enough data and a dispatch function then
240 * call the function and get the next packet.
241 * Otherwise return the packet type to the caller so it
242 * can decide how to go on.
243 *
244 * We will only call the dispatch function for:
245 * 20-29 Algorithm negotiation
246 * 30-49 Key exchange method specific (numbers can be reused for
247 * different authentication methods)
248 */
249 for (;;) {
250 if ((r = ssh_packet_read_poll2(ssh, &type, &seqnr)) != 0)
251 return r;
252 if (type > 0 && type < DISPATCH_MAX &&
253 type >= SSH2_MSG_KEXINIT && type <= SSH2_MSG_TRANSPORT_MAX &&
254 ssh->dispatch[type] != NULL) {
255 if ((r = (*ssh->dispatch[type])(type, seqnr, ssh)) != 0)
256 return r;
257 } else {
258 *typep = type;
259 return 0;
260 }
261 }
262}
263
264const u_char *
265ssh_packet_payload(struct ssh *ssh, size_t *lenp)
266{
267 return sshpkt_ptr(ssh, lenp);
268}
269
270int
271ssh_packet_put(struct ssh *ssh, int type, const u_char *data, size_t len)
272{
273 int r;
274
275 if ((r = sshpkt_start(ssh, type)) != 0 ||
276 (r = sshpkt_put(ssh, data, len)) != 0 ||
277 (r = sshpkt_send(ssh)) != 0)
278 return r;
279 return 0;
280}
281
282const u_char *
283ssh_output_ptr(struct ssh *ssh, size_t *len)
284{
285 struct sshbuf *output = ssh_packet_get_output(ssh);
286
287 *len = sshbuf_len(output);
288 return sshbuf_ptr(output);
289}
290
291int
292ssh_output_consume(struct ssh *ssh, size_t len)
293{
294 return sshbuf_consume(ssh_packet_get_output(ssh), len);
295}
296
297int
298ssh_output_space(struct ssh *ssh, size_t len)
299{
300 return (0 == sshbuf_check_reserve(ssh_packet_get_output(ssh), len));
301}
302
303int
304ssh_input_space(struct ssh *ssh, size_t len)
305{
306 return (0 == sshbuf_check_reserve(ssh_packet_get_input(ssh), len));
307}
308
309/* Read other side's version identification. */
310int
311_ssh_read_banner(struct ssh *ssh, char **bannerp)
312{
313 struct sshbuf *input;
314 const char *s;
315 char buf[256], remote_version[256]; /* must be same size! */
316 const char *mismatch = "Protocol mismatch.\r\n";
317 int r, remote_major, remote_minor;
318 size_t i, n, j, len;
319
320 *bannerp = NULL;
321 input = ssh_packet_get_input(ssh);
322 len = sshbuf_len(input);
323 s = (const char *)sshbuf_ptr(input);
324 for (j = n = 0;;) {
325 for (i = 0; i < sizeof(buf) - 1; i++) {
326 if (j >= len)
327 return (0);
328 buf[i] = s[j++];
329 if (buf[i] == '\r') {
330 buf[i] = '\n';
331 buf[i + 1] = 0;
332 continue; /**XXX wait for \n */
333 }
334 if (buf[i] == '\n') {
335 buf[i + 1] = 0;
336 break;
337 }
338 }
339 buf[sizeof(buf) - 1] = 0;
340 if (strncmp(buf, "SSH-", 4) == 0)
341 break;
342 debug("ssh_exchange_identification: %s", buf);
343 if (ssh->kex->server || ++n > 65536) {
344 if ((r = sshbuf_put(ssh_packet_get_output(ssh),
345 mismatch, strlen(mismatch))) != 0)
346 return r;
347 return SSH_ERR_NO_PROTOCOL_VERSION;
348 }
349 }
350 if ((r = sshbuf_consume(input, j)) != 0)
351 return r;
352
353 /*
354 * Check that the versions match. In future this might accept
355 * several versions and set appropriate flags to handle them.
356 */
357 if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
358 &remote_major, &remote_minor, remote_version) != 3)
359 return SSH_ERR_INVALID_FORMAT;
360 debug("Remote protocol version %d.%d, remote software version %.100s",
361 remote_major, remote_minor, remote_version);
362
363 ssh->compat = compat_datafellows(remote_version);
364 if (remote_major == 1 && remote_minor == 99) {
365 remote_major = 2;
366 remote_minor = 0;
367 }
368 if (remote_major != 2)
369 return SSH_ERR_PROTOCOL_MISMATCH;
370 enable_compat20();
371 chop(buf);
372 debug("Remote version string %.100s", buf);
373 if ((*bannerp = strdup(buf)) == NULL)
374 return SSH_ERR_ALLOC_FAIL;
375 return 0;
376}
377
378/* Send our own protocol version identification. */
379int
380_ssh_send_banner(struct ssh *ssh, char **bannerp)
381{
382 char buf[256];
383 int r;
384
385 snprintf(buf, sizeof buf, "SSH-2.0-%.100s\r\n", SSH_VERSION);
386 if ((r = sshbuf_put(ssh_packet_get_output(ssh), buf, strlen(buf))) != 0)
387 return r;
388 chop(buf);
389 debug("Local version string %.100s", buf);
390 if ((*bannerp = strdup(buf)) == NULL)
391 return SSH_ERR_ALLOC_FAIL;
392 return 0;
393}
394
395int
396_ssh_exchange_banner(struct ssh *ssh)
397{
398 struct kex *kex = ssh->kex;
399 int r;
400
401 /*
402 * if _ssh_read_banner() cannot parse a full version string
403 * it will return NULL and we end up calling it again.
404 */
405
406 r = 0;
407 if (kex->server) {
408 if (kex->server_version_string == NULL)
409 r = _ssh_send_banner(ssh, &kex->server_version_string);
410 if (r == 0 &&
411 kex->server_version_string != NULL &&
412 kex->client_version_string == NULL)
413 r = _ssh_read_banner(ssh, &kex->client_version_string);
414 } else {
415 if (kex->server_version_string == NULL)
416 r = _ssh_read_banner(ssh, &kex->server_version_string);
417 if (r == 0 &&
418 kex->server_version_string != NULL &&
419 kex->client_version_string == NULL)
420 r = _ssh_send_banner(ssh, &kex->client_version_string);
421 }
422 if (r != 0)
423 return r;
424 /* start initial kex as soon as we have exchanged the banners */
425 if (kex->server_version_string != NULL &&
426 kex->client_version_string != NULL) {
427 if ((r = _ssh_order_hostkeyalgs(ssh)) != 0 ||
428 (r = kex_send_kexinit(ssh)) != 0)
429 return r;
430 }
431 return 0;
432}
433
434struct sshkey *
djm@openbsd.org5104db72015-01-26 06:10:03 +0000435_ssh_host_public_key(int type, int nid, struct ssh *ssh)
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000436{
437 struct key_entry *k;
438
439 debug3("%s: need %d", __func__, type);
440 TAILQ_FOREACH(k, &ssh->public_keys, next) {
441 debug3("%s: check %s", __func__, sshkey_type(k->key));
djm@openbsd.org5104db72015-01-26 06:10:03 +0000442 if (k->key->type == type &&
443 (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000444 return (k->key);
445 }
446 return (NULL);
447}
448
449struct sshkey *
djm@openbsd.org5104db72015-01-26 06:10:03 +0000450_ssh_host_private_key(int type, int nid, struct ssh *ssh)
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000451{
452 struct key_entry *k;
453
454 debug3("%s: need %d", __func__, type);
455 TAILQ_FOREACH(k, &ssh->private_keys, next) {
456 debug3("%s: check %s", __func__, sshkey_type(k->key));
djm@openbsd.org5104db72015-01-26 06:10:03 +0000457 if (k->key->type == type &&
458 (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000459 return (k->key);
460 }
461 return (NULL);
462}
463
464int
465_ssh_verify_host_key(struct sshkey *hostkey, struct ssh *ssh)
466{
467 struct key_entry *k;
468
469 debug3("%s: need %s", __func__, sshkey_type(hostkey));
470 TAILQ_FOREACH(k, &ssh->public_keys, next) {
471 debug3("%s: check %s", __func__, sshkey_type(k->key));
472 if (sshkey_equal_public(hostkey, k->key))
473 return (0); /* ok */
474 }
475 return (-1); /* failed */
476}
477
478/* offer hostkey algorithms in kexinit depending on registered keys */
479int
480_ssh_order_hostkeyalgs(struct ssh *ssh)
481{
482 struct key_entry *k;
483 char *orig, *avail, *oavail = NULL, *alg, *replace = NULL;
484 char **proposal;
485 size_t maxlen;
486 int ktype, r;
487
488 /* XXX we de-serialize ssh->kex->my, modify it, and change it */
489 if ((r = kex_buf2prop(ssh->kex->my, NULL, &proposal)) != 0)
490 return r;
491 orig = proposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
492 if ((oavail = avail = strdup(orig)) == NULL) {
493 r = SSH_ERR_ALLOC_FAIL;
494 goto out;
495 }
496 maxlen = strlen(avail) + 1;
497 if ((replace = calloc(1, maxlen)) == NULL) {
498 r = SSH_ERR_ALLOC_FAIL;
499 goto out;
500 }
501 *replace = '\0';
502 while ((alg = strsep(&avail, ",")) && *alg != '\0') {
503 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
504 continue;
505 TAILQ_FOREACH(k, &ssh->public_keys, next) {
506 if (k->key->type == ktype ||
507 (sshkey_is_cert(k->key) && k->key->type ==
508 sshkey_type_plain(ktype))) {
509 if (*replace != '\0')
510 strlcat(replace, ",", maxlen);
511 strlcat(replace, alg, maxlen);
512 break;
513 }
514 }
515 }
516 if (*replace != '\0') {
517 debug2("%s: orig/%d %s", __func__, ssh->kex->server, orig);
518 debug2("%s: replace/%d %s", __func__, ssh->kex->server, replace);
519 free(orig);
520 proposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = replace;
521 replace = NULL; /* owned by proposal */
522 r = kex_prop2buf(ssh->kex->my, proposal);
523 }
524 out:
525 free(oavail);
526 free(replace);
527 kex_prop_free(proposal);
528 return r;
529}
530
531int
532_ssh_host_key_sign(struct sshkey *privkey, struct sshkey *pubkey,
djm@openbsd.org523463a2015-02-16 22:13:32 +0000533 u_char **signature, size_t *slen,
534 const u_char *data, size_t dlen, u_int compat)
markus@openbsd.orgf582f0e2015-01-19 20:30:23 +0000535{
536 return sshkey_sign(privkey, signature, slen, data, dlen, compat);
537}