1 /* $OpenBSD: ssh_api.c,v 1.4 2015/02/16 22:13:32 djm Exp $ */
3 * Copyright (c) 2012 Markus Friedl. All rights reserved.
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.
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.
20 #include "ssh1.h" /* For SSH_MSG_NONE */
30 #include "myproposal.h"
36 int _ssh_exchange_banner(struct ssh *);
37 int _ssh_send_banner(struct ssh *, char **);
38 int _ssh_read_banner(struct ssh *, char **);
39 int _ssh_order_hostkeyalgs(struct ssh *);
40 int _ssh_verify_host_key(struct sshkey *, struct ssh *);
41 struct sshkey *_ssh_host_public_key(int, int, struct ssh *);
42 struct sshkey *_ssh_host_private_key(int, int, struct ssh *);
43 int _ssh_host_key_sign(struct sshkey *, struct sshkey *, u_char **,
44 size_t *, const u_char *, size_t, u_int);
47 * stubs for the server side implementation of kex.
48 * disable privsep so our stubs will never be called.
51 int mm_sshkey_sign(struct sshkey *, u_char **, u_int *,
52 u_char *, u_int, u_int);
53 DH *mm_choose_dh(int, int, int);
55 /* Define these two variables here so that they are part of the library */
56 u_char *session_id2 = NULL;
57 u_int session_id2_len = 0;
60 mm_sshkey_sign(struct sshkey *key, u_char **sigp, u_int *lenp,
61 u_char *data, u_int datalen, u_int compat)
67 mm_choose_dh(int min, int nbits, int max)
75 ssh_init(struct ssh **sshp, int is_server, struct kex_params *kex_params)
77 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
85 OpenSSL_add_all_algorithms();
86 #endif /* WITH_OPENSSL */
90 if ((ssh = ssh_packet_set_connection(NULL, -1, -1)) == NULL)
91 return SSH_ERR_ALLOC_FAIL;
93 ssh_packet_set_server(ssh);
95 /* Initialize key exchange */
96 proposal = kex_params ? kex_params->proposal : myproposal;
97 if ((r = kex_new(ssh, proposal, &ssh->kex)) != 0) {
101 ssh->kex->server = is_server;
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;
108 # ifdef OPENSSL_HAS_ECC
109 ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
111 #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;
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;
122 # ifdef OPENSSL_HAS_ECC
123 ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
125 #endif /* WITH_OPENSSL */
126 ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
127 ssh->kex->verify_host_key =&_ssh_verify_host_key;
134 ssh_free(struct ssh *ssh)
138 ssh_packet_close(ssh);
140 * we've only created the public keys variants in case we
141 * are a acting as a server.
143 while ((k = TAILQ_FIRST(&ssh->public_keys)) != NULL) {
144 TAILQ_REMOVE(&ssh->public_keys, k, next);
145 if (ssh->kex && ssh->kex->server)
149 while ((k = TAILQ_FIRST(&ssh->private_keys)) != NULL) {
150 TAILQ_REMOVE(&ssh->private_keys, k, next);
159 ssh_set_app_data(struct ssh *ssh, void *app_data)
161 ssh->app_data = app_data;
165 ssh_get_app_data(struct ssh *ssh)
167 return ssh->app_data;
170 /* Returns < 0 on error, 0 otherwise */
172 ssh_add_hostkey(struct ssh *ssh, struct sshkey *key)
174 struct sshkey *pubkey = NULL;
175 struct key_entry *k = NULL, *k_prv = NULL;
178 if (ssh->kex->server) {
179 if ((r = sshkey_from_private(key, &pubkey)) != 0)
181 if ((k = malloc(sizeof(*k))) == NULL ||
182 (k_prv = malloc(sizeof(*k_prv))) == NULL) {
185 return SSH_ERR_ALLOC_FAIL;
188 TAILQ_INSERT_TAIL(&ssh->private_keys, k_prv, next);
190 /* add the public key, too */
192 TAILQ_INSERT_TAIL(&ssh->public_keys, k, next);
195 if ((k = malloc(sizeof(*k))) == NULL)
196 return SSH_ERR_ALLOC_FAIL;
198 TAILQ_INSERT_TAIL(&ssh->public_keys, k, next);
206 ssh_set_verify_host_key_callback(struct ssh *ssh,
207 int (*cb)(struct sshkey *, struct ssh *))
209 if (cb == NULL || ssh->kex == NULL)
210 return SSH_ERR_INVALID_ARGUMENT;
212 ssh->kex->verify_host_key = cb;
218 ssh_input_append(struct ssh *ssh, const u_char *data, size_t len)
220 return sshbuf_put(ssh_packet_get_input(ssh), data, len);
224 ssh_packet_next(struct ssh *ssh, u_char *typep)
231 * Try to read a packet. Return SSH_MSG_NONE if no packet or not
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);
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.
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)
250 if ((r = ssh_packet_read_poll2(ssh, &type, &seqnr)) != 0)
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)
265 ssh_packet_payload(struct ssh *ssh, size_t *lenp)
267 return sshpkt_ptr(ssh, lenp);
271 ssh_packet_put(struct ssh *ssh, int type, const u_char *data, size_t len)
275 if ((r = sshpkt_start(ssh, type)) != 0 ||
276 (r = sshpkt_put(ssh, data, len)) != 0 ||
277 (r = sshpkt_send(ssh)) != 0)
283 ssh_output_ptr(struct ssh *ssh, size_t *len)
285 struct sshbuf *output = ssh_packet_get_output(ssh);
287 *len = sshbuf_len(output);
288 return sshbuf_ptr(output);
292 ssh_output_consume(struct ssh *ssh, size_t len)
294 return sshbuf_consume(ssh_packet_get_output(ssh), len);
298 ssh_output_space(struct ssh *ssh, size_t len)
300 return (0 == sshbuf_check_reserve(ssh_packet_get_output(ssh), len));
304 ssh_input_space(struct ssh *ssh, size_t len)
306 return (0 == sshbuf_check_reserve(ssh_packet_get_input(ssh), len));
309 /* Read other side's version identification. */
311 _ssh_read_banner(struct ssh *ssh, char **bannerp)
313 struct sshbuf *input;
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;
321 input = ssh_packet_get_input(ssh);
322 len = sshbuf_len(input);
323 s = (const char *)sshbuf_ptr(input);
325 for (i = 0; i < sizeof(buf) - 1; i++) {
329 if (buf[i] == '\r') {
332 continue; /**XXX wait for \n */
334 if (buf[i] == '\n') {
339 buf[sizeof(buf) - 1] = 0;
340 if (strncmp(buf, "SSH-", 4) == 0)
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)
347 return SSH_ERR_NO_PROTOCOL_VERSION;
350 if ((r = sshbuf_consume(input, j)) != 0)
354 * Check that the versions match. In future this might accept
355 * several versions and set appropriate flags to handle them.
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);
363 ssh->compat = compat_datafellows(remote_version);
364 if (remote_major == 1 && remote_minor == 99) {
368 if (remote_major != 2)
369 return SSH_ERR_PROTOCOL_MISMATCH;
372 debug("Remote version string %.100s", buf);
373 if ((*bannerp = strdup(buf)) == NULL)
374 return SSH_ERR_ALLOC_FAIL;
378 /* Send our own protocol version identification. */
380 _ssh_send_banner(struct ssh *ssh, char **bannerp)
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)
389 debug("Local version string %.100s", buf);
390 if ((*bannerp = strdup(buf)) == NULL)
391 return SSH_ERR_ALLOC_FAIL;
396 _ssh_exchange_banner(struct ssh *ssh)
398 struct kex *kex = ssh->kex;
402 * if _ssh_read_banner() cannot parse a full version string
403 * it will return NULL and we end up calling it again.
408 if (kex->server_version_string == NULL)
409 r = _ssh_send_banner(ssh, &kex->server_version_string);
411 kex->server_version_string != NULL &&
412 kex->client_version_string == NULL)
413 r = _ssh_read_banner(ssh, &kex->client_version_string);
415 if (kex->server_version_string == NULL)
416 r = _ssh_read_banner(ssh, &kex->server_version_string);
418 kex->server_version_string != NULL &&
419 kex->client_version_string == NULL)
420 r = _ssh_send_banner(ssh, &kex->client_version_string);
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)
435 _ssh_host_public_key(int type, int nid, struct ssh *ssh)
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));
442 if (k->key->type == type &&
443 (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
450 _ssh_host_private_key(int type, int nid, struct ssh *ssh)
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));
457 if (k->key->type == type &&
458 (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
465 _ssh_verify_host_key(struct sshkey *hostkey, struct ssh *ssh)
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))
475 return (-1); /* failed */
478 /* offer hostkey algorithms in kexinit depending on registered keys */
480 _ssh_order_hostkeyalgs(struct ssh *ssh)
483 char *orig, *avail, *oavail = NULL, *alg, *replace = NULL;
488 /* XXX we de-serialize ssh->kex->my, modify it, and change it */
489 if ((r = kex_buf2prop(ssh->kex->my, NULL, &proposal)) != 0)
491 orig = proposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
492 if ((oavail = avail = strdup(orig)) == NULL) {
493 r = SSH_ERR_ALLOC_FAIL;
496 maxlen = strlen(avail) + 1;
497 if ((replace = calloc(1, maxlen)) == NULL) {
498 r = SSH_ERR_ALLOC_FAIL;
502 while ((alg = strsep(&avail, ",")) && *alg != '\0') {
503 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
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);
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);
520 proposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = replace;
521 replace = NULL; /* owned by proposal */
522 r = kex_prop2buf(ssh->kex->my, proposal);
527 kex_prop_free(proposal);
532 _ssh_host_key_sign(struct sshkey *privkey, struct sshkey *pubkey,
533 u_char **signature, size_t *slen,
534 const u_char *data, size_t dlen, u_int compat)
536 return sshkey_sign(privkey, signature, slen, data, dlen, compat);