Annotation of src/usr.bin/ssh/ssh_api.c, Revision 1.11
1.11 ! djm 1: /* $OpenBSD: ssh_api.c,v 1.10 2019/01/19 21:43:56 djm Exp $ */
1.1 markus 2: /*
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 "ssh_api.h"
19: #include "compat.h"
20: #include "log.h"
21: #include "authfile.h"
22: #include "sshkey.h"
23: #include "misc.h"
24: #include "ssh2.h"
25: #include "version.h"
26: #include "myproposal.h"
27: #include "ssherr.h"
28: #include "sshbuf.h"
29:
30: #include <string.h>
31:
32: int _ssh_exchange_banner(struct ssh *);
1.9 djm 33: int _ssh_send_banner(struct ssh *, struct sshbuf *);
34: int _ssh_read_banner(struct ssh *, struct sshbuf *);
1.1 markus 35: int _ssh_order_hostkeyalgs(struct ssh *);
36: int _ssh_verify_host_key(struct sshkey *, struct ssh *);
1.2 djm 37: struct sshkey *_ssh_host_public_key(int, int, struct ssh *);
38: struct sshkey *_ssh_host_private_key(int, int, struct ssh *);
1.10 djm 39: int _ssh_host_key_sign(struct ssh *, struct sshkey *, struct sshkey *,
40: u_char **, size_t *, const u_char *, size_t, const char *);
1.1 markus 41:
42: /*
43: * stubs for the server side implementation of kex.
44: * disable privsep so our stubs will never be called.
45: */
46: int use_privsep = 0;
47: int mm_sshkey_sign(struct sshkey *, u_char **, u_int *,
1.5 markus 48: u_char *, u_int, char *, u_int);
1.1 markus 49: DH *mm_choose_dh(int, int, int);
50:
51: /* Define these two variables here so that they are part of the library */
52: u_char *session_id2 = NULL;
53: u_int session_id2_len = 0;
54:
55: int
56: mm_sshkey_sign(struct sshkey *key, u_char **sigp, u_int *lenp,
1.5 markus 57: u_char *data, u_int datalen, char *alg, u_int compat)
1.1 markus 58: {
59: return (-1);
60: }
61:
62: DH *
63: mm_choose_dh(int min, int nbits, int max)
64: {
65: return (NULL);
66: }
67:
68: /* API */
69:
70: int
71: ssh_init(struct ssh **sshp, int is_server, struct kex_params *kex_params)
72: {
73: char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
74: struct ssh *ssh;
75: char **proposal;
76: static int called;
77: int r;
78:
79: if (!called) {
80: OpenSSL_add_all_algorithms();
81: called = 1;
82: }
83:
1.3 djm 84: if ((ssh = ssh_packet_set_connection(NULL, -1, -1)) == NULL)
85: return SSH_ERR_ALLOC_FAIL;
1.1 markus 86: if (is_server)
87: ssh_packet_set_server(ssh);
88:
89: /* Initialize key exchange */
90: proposal = kex_params ? kex_params->proposal : myproposal;
1.9 djm 91: if ((r = kex_ready(ssh, proposal)) != 0) {
1.1 markus 92: ssh_free(ssh);
93: return r;
94: }
95: ssh->kex->server = is_server;
96: if (is_server) {
97: #ifdef WITH_OPENSSL
98: ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
99: ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1.6 djm 100: ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
101: ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
102: ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
1.1 markus 103: ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
104: ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
105: ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
106: #endif /* WITH_OPENSSL */
107: ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_server;
1.11 ! djm 108: ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_kem_server;
1.1 markus 109: ssh->kex->load_host_public_key=&_ssh_host_public_key;
110: ssh->kex->load_host_private_key=&_ssh_host_private_key;
111: ssh->kex->sign=&_ssh_host_key_sign;
112: } else {
113: #ifdef WITH_OPENSSL
114: ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
115: ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
1.6 djm 116: ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
117: ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
118: ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
1.1 markus 119: ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
120: ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
121: ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
122: #endif /* WITH_OPENSSL */
123: ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
1.11 ! djm 124: ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_kem_client;
1.1 markus 125: ssh->kex->verify_host_key =&_ssh_verify_host_key;
126: }
127: *sshp = ssh;
128: return 0;
129: }
130:
131: void
132: ssh_free(struct ssh *ssh)
133: {
134: struct key_entry *k;
135:
136: ssh_packet_close(ssh);
137: /*
138: * we've only created the public keys variants in case we
139: * are a acting as a server.
140: */
141: while ((k = TAILQ_FIRST(&ssh->public_keys)) != NULL) {
142: TAILQ_REMOVE(&ssh->public_keys, k, next);
143: if (ssh->kex && ssh->kex->server)
144: sshkey_free(k->key);
145: free(k);
146: }
147: while ((k = TAILQ_FIRST(&ssh->private_keys)) != NULL) {
148: TAILQ_REMOVE(&ssh->private_keys, k, next);
149: free(k);
150: }
151: if (ssh->kex)
152: kex_free(ssh->kex);
153: free(ssh);
154: }
155:
156: void
157: ssh_set_app_data(struct ssh *ssh, void *app_data)
158: {
159: ssh->app_data = app_data;
160: }
161:
162: void *
163: ssh_get_app_data(struct ssh *ssh)
164: {
165: return ssh->app_data;
166: }
167:
168: /* Returns < 0 on error, 0 otherwise */
169: int
170: ssh_add_hostkey(struct ssh *ssh, struct sshkey *key)
171: {
172: struct sshkey *pubkey = NULL;
173: struct key_entry *k = NULL, *k_prv = NULL;
174: int r;
175:
176: if (ssh->kex->server) {
177: if ((r = sshkey_from_private(key, &pubkey)) != 0)
178: return r;
179: if ((k = malloc(sizeof(*k))) == NULL ||
180: (k_prv = malloc(sizeof(*k_prv))) == NULL) {
181: free(k);
182: sshkey_free(pubkey);
183: return SSH_ERR_ALLOC_FAIL;
184: }
185: k_prv->key = key;
186: TAILQ_INSERT_TAIL(&ssh->private_keys, k_prv, next);
187:
188: /* add the public key, too */
189: k->key = pubkey;
190: TAILQ_INSERT_TAIL(&ssh->public_keys, k, next);
191: r = 0;
192: } else {
193: if ((k = malloc(sizeof(*k))) == NULL)
194: return SSH_ERR_ALLOC_FAIL;
195: k->key = key;
196: TAILQ_INSERT_TAIL(&ssh->public_keys, k, next);
197: r = 0;
198: }
199:
200: return r;
201: }
202:
203: int
204: ssh_set_verify_host_key_callback(struct ssh *ssh,
205: int (*cb)(struct sshkey *, struct ssh *))
206: {
207: if (cb == NULL || ssh->kex == NULL)
208: return SSH_ERR_INVALID_ARGUMENT;
209:
210: ssh->kex->verify_host_key = cb;
211:
212: return 0;
213: }
214:
215: int
216: ssh_input_append(struct ssh *ssh, const u_char *data, size_t len)
217: {
218: return sshbuf_put(ssh_packet_get_input(ssh), data, len);
219: }
220:
221: int
222: ssh_packet_next(struct ssh *ssh, u_char *typep)
223: {
224: int r;
225: u_int32_t seqnr;
226: u_char type;
227:
228: /*
229: * Try to read a packet. Return SSH_MSG_NONE if no packet or not
230: * enough data.
231: */
232: *typep = SSH_MSG_NONE;
1.9 djm 233: if (sshbuf_len(ssh->kex->client_version) == 0 ||
234: sshbuf_len(ssh->kex->server_version) == 0)
1.1 markus 235: return _ssh_exchange_banner(ssh);
236: /*
237: * If we enough data and a dispatch function then
238: * call the function and get the next packet.
239: * Otherwise return the packet type to the caller so it
240: * can decide how to go on.
241: *
242: * We will only call the dispatch function for:
243: * 20-29 Algorithm negotiation
244: * 30-49 Key exchange method specific (numbers can be reused for
245: * different authentication methods)
246: */
247: for (;;) {
248: if ((r = ssh_packet_read_poll2(ssh, &type, &seqnr)) != 0)
249: return r;
250: if (type > 0 && type < DISPATCH_MAX &&
251: type >= SSH2_MSG_KEXINIT && type <= SSH2_MSG_TRANSPORT_MAX &&
252: ssh->dispatch[type] != NULL) {
253: if ((r = (*ssh->dispatch[type])(type, seqnr, ssh)) != 0)
254: return r;
255: } else {
256: *typep = type;
257: return 0;
258: }
259: }
260: }
261:
262: const u_char *
263: ssh_packet_payload(struct ssh *ssh, size_t *lenp)
264: {
265: return sshpkt_ptr(ssh, lenp);
266: }
267:
268: int
269: ssh_packet_put(struct ssh *ssh, int type, const u_char *data, size_t len)
270: {
271: int r;
272:
273: if ((r = sshpkt_start(ssh, type)) != 0 ||
274: (r = sshpkt_put(ssh, data, len)) != 0 ||
275: (r = sshpkt_send(ssh)) != 0)
276: return r;
277: return 0;
278: }
279:
280: const u_char *
281: ssh_output_ptr(struct ssh *ssh, size_t *len)
282: {
283: struct sshbuf *output = ssh_packet_get_output(ssh);
284:
285: *len = sshbuf_len(output);
286: return sshbuf_ptr(output);
287: }
288:
289: int
290: ssh_output_consume(struct ssh *ssh, size_t len)
291: {
292: return sshbuf_consume(ssh_packet_get_output(ssh), len);
293: }
294:
295: int
296: ssh_output_space(struct ssh *ssh, size_t len)
297: {
298: return (0 == sshbuf_check_reserve(ssh_packet_get_output(ssh), len));
299: }
300:
301: int
302: ssh_input_space(struct ssh *ssh, size_t len)
303: {
304: return (0 == sshbuf_check_reserve(ssh_packet_get_input(ssh), len));
305: }
306:
307: /* Read other side's version identification. */
308: int
1.9 djm 309: _ssh_read_banner(struct ssh *ssh, struct sshbuf *banner)
1.1 markus 310: {
1.9 djm 311: struct sshbuf *input = ssh_packet_get_input(ssh);
1.1 markus 312: const char *mismatch = "Protocol mismatch.\r\n";
1.9 djm 313: const u_char *s = sshbuf_ptr(input);
314: u_char c;
315: char *cp, *remote_version;
316: int r, remote_major, remote_minor, expect_nl;
317: size_t n, j;
1.1 markus 318:
319: for (j = n = 0;;) {
1.9 djm 320: sshbuf_reset(banner);
321: expect_nl = 0;
322: for (;;) {
323: if (j >= sshbuf_len(input))
324: return 0; /* insufficient data in input buf */
325: c = s[j++];
326: if (c == '\r') {
327: expect_nl = 1;
328: continue;
1.1 markus 329: }
1.9 djm 330: if (c == '\n')
1.1 markus 331: break;
1.9 djm 332: if (expect_nl)
333: goto bad;
334: if ((r = sshbuf_put_u8(banner, c)) != 0)
335: return r;
336: if (sshbuf_len(banner) > SSH_MAX_BANNER_LEN)
337: goto bad;
1.1 markus 338: }
1.9 djm 339: if (sshbuf_len(banner) >= 4 &&
340: memcmp(sshbuf_ptr(banner), "SSH-", 4) == 0)
1.1 markus 341: break;
1.9 djm 342: if ((cp = sshbuf_dup_string(banner)) == NULL)
343: return SSH_ERR_ALLOC_FAIL;
344: debug("%s: %s", __func__, cp);
345: free(cp);
346: /* Accept lines before banner only on client */
347: if (ssh->kex->server || ++n > SSH_MAX_PRE_BANNER_LINES) {
348: bad:
1.1 markus 349: if ((r = sshbuf_put(ssh_packet_get_output(ssh),
350: mismatch, strlen(mismatch))) != 0)
351: return r;
352: return SSH_ERR_NO_PROTOCOL_VERSION;
353: }
354: }
355: if ((r = sshbuf_consume(input, j)) != 0)
356: return r;
357:
1.9 djm 358: if ((cp = sshbuf_dup_string(banner)) == NULL)
359: return SSH_ERR_ALLOC_FAIL;
360: /* XXX remote version must be the same size as banner for sscanf */
361: if ((remote_version = calloc(1, sshbuf_len(banner))) == NULL)
362: return SSH_ERR_ALLOC_FAIL;
363:
1.1 markus 364: /*
365: * Check that the versions match. In future this might accept
366: * several versions and set appropriate flags to handle them.
367: */
1.9 djm 368: if (sscanf(cp, "SSH-%d.%d-%[^\n]\n",
1.1 markus 369: &remote_major, &remote_minor, remote_version) != 3)
370: return SSH_ERR_INVALID_FORMAT;
371: debug("Remote protocol version %d.%d, remote software version %.100s",
372: remote_major, remote_minor, remote_version);
373:
374: ssh->compat = compat_datafellows(remote_version);
375: if (remote_major == 1 && remote_minor == 99) {
376: remote_major = 2;
377: remote_minor = 0;
378: }
379: if (remote_major != 2)
380: return SSH_ERR_PROTOCOL_MISMATCH;
1.9 djm 381: debug("Remote version string %.100s", cp);
382: free(cp);
1.1 markus 383: return 0;
384: }
385:
386: /* Send our own protocol version identification. */
387: int
1.9 djm 388: _ssh_send_banner(struct ssh *ssh, struct sshbuf *banner)
1.1 markus 389: {
1.9 djm 390: char *cp;
1.1 markus 391: int r;
392:
1.9 djm 393: if ((r = sshbuf_putf(banner, "SSH-2.0-%.100s\r\n", SSH_VERSION)) != 0)
394: return r;
395: if ((r = sshbuf_putb(ssh_packet_get_output(ssh), banner)) != 0)
396: return r;
397: /* Remove trailing \r\n */
398: if ((r = sshbuf_consume_end(banner, 2)) != 0)
1.1 markus 399: return r;
1.9 djm 400: if ((cp = sshbuf_dup_string(banner)) == NULL)
1.1 markus 401: return SSH_ERR_ALLOC_FAIL;
1.9 djm 402: debug("Local version string %.100s", cp);
403: free(cp);
1.1 markus 404: return 0;
405: }
406:
407: int
408: _ssh_exchange_banner(struct ssh *ssh)
409: {
410: struct kex *kex = ssh->kex;
411: int r;
412:
413: /*
414: * if _ssh_read_banner() cannot parse a full version string
415: * it will return NULL and we end up calling it again.
416: */
417:
418: r = 0;
419: if (kex->server) {
1.9 djm 420: if (sshbuf_len(ssh->kex->server_version) == 0)
421: r = _ssh_send_banner(ssh, ssh->kex->server_version);
1.1 markus 422: if (r == 0 &&
1.9 djm 423: sshbuf_len(ssh->kex->server_version) != 0 &&
424: sshbuf_len(ssh->kex->client_version) == 0)
425: r = _ssh_read_banner(ssh, ssh->kex->client_version);
1.1 markus 426: } else {
1.9 djm 427: if (sshbuf_len(ssh->kex->server_version) == 0)
428: r = _ssh_read_banner(ssh, ssh->kex->server_version);
1.1 markus 429: if (r == 0 &&
1.9 djm 430: sshbuf_len(ssh->kex->server_version) != 0 &&
431: sshbuf_len(ssh->kex->client_version) == 0)
432: r = _ssh_send_banner(ssh, ssh->kex->client_version);
1.1 markus 433: }
434: if (r != 0)
435: return r;
436: /* start initial kex as soon as we have exchanged the banners */
1.9 djm 437: if (sshbuf_len(ssh->kex->server_version) != 0 &&
438: sshbuf_len(ssh->kex->client_version) != 0) {
1.1 markus 439: if ((r = _ssh_order_hostkeyalgs(ssh)) != 0 ||
440: (r = kex_send_kexinit(ssh)) != 0)
441: return r;
442: }
443: return 0;
444: }
445:
446: struct sshkey *
1.2 djm 447: _ssh_host_public_key(int type, int nid, struct ssh *ssh)
1.1 markus 448: {
449: struct key_entry *k;
450:
451: debug3("%s: need %d", __func__, type);
452: TAILQ_FOREACH(k, &ssh->public_keys, next) {
453: debug3("%s: check %s", __func__, sshkey_type(k->key));
1.2 djm 454: if (k->key->type == type &&
455: (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
1.1 markus 456: return (k->key);
457: }
458: return (NULL);
459: }
460:
461: struct sshkey *
1.2 djm 462: _ssh_host_private_key(int type, int nid, struct ssh *ssh)
1.1 markus 463: {
464: struct key_entry *k;
465:
466: debug3("%s: need %d", __func__, type);
467: TAILQ_FOREACH(k, &ssh->private_keys, next) {
468: debug3("%s: check %s", __func__, sshkey_type(k->key));
1.2 djm 469: if (k->key->type == type &&
470: (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
1.1 markus 471: return (k->key);
472: }
473: return (NULL);
474: }
475:
476: int
477: _ssh_verify_host_key(struct sshkey *hostkey, struct ssh *ssh)
478: {
479: struct key_entry *k;
480:
481: debug3("%s: need %s", __func__, sshkey_type(hostkey));
482: TAILQ_FOREACH(k, &ssh->public_keys, next) {
483: debug3("%s: check %s", __func__, sshkey_type(k->key));
484: if (sshkey_equal_public(hostkey, k->key))
485: return (0); /* ok */
486: }
487: return (-1); /* failed */
488: }
489:
490: /* offer hostkey algorithms in kexinit depending on registered keys */
491: int
492: _ssh_order_hostkeyalgs(struct ssh *ssh)
493: {
494: struct key_entry *k;
495: char *orig, *avail, *oavail = NULL, *alg, *replace = NULL;
496: char **proposal;
497: size_t maxlen;
498: int ktype, r;
499:
500: /* XXX we de-serialize ssh->kex->my, modify it, and change it */
501: if ((r = kex_buf2prop(ssh->kex->my, NULL, &proposal)) != 0)
502: return r;
503: orig = proposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
504: if ((oavail = avail = strdup(orig)) == NULL) {
505: r = SSH_ERR_ALLOC_FAIL;
506: goto out;
507: }
508: maxlen = strlen(avail) + 1;
509: if ((replace = calloc(1, maxlen)) == NULL) {
510: r = SSH_ERR_ALLOC_FAIL;
511: goto out;
512: }
513: *replace = '\0';
514: while ((alg = strsep(&avail, ",")) && *alg != '\0') {
515: if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
516: continue;
517: TAILQ_FOREACH(k, &ssh->public_keys, next) {
518: if (k->key->type == ktype ||
519: (sshkey_is_cert(k->key) && k->key->type ==
520: sshkey_type_plain(ktype))) {
521: if (*replace != '\0')
522: strlcat(replace, ",", maxlen);
523: strlcat(replace, alg, maxlen);
524: break;
525: }
526: }
527: }
528: if (*replace != '\0') {
529: debug2("%s: orig/%d %s", __func__, ssh->kex->server, orig);
530: debug2("%s: replace/%d %s", __func__, ssh->kex->server, replace);
531: free(orig);
532: proposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = replace;
533: replace = NULL; /* owned by proposal */
534: r = kex_prop2buf(ssh->kex->my, proposal);
535: }
536: out:
537: free(oavail);
538: free(replace);
539: kex_prop_free(proposal);
540: return r;
541: }
542:
543: int
1.10 djm 544: _ssh_host_key_sign(struct ssh *ssh, struct sshkey *privkey,
545: struct sshkey *pubkey, u_char **signature, size_t *slen,
546: const u_char *data, size_t dlen, const char *alg)
1.1 markus 547: {
1.10 djm 548: return sshkey_sign(privkey, signature, slen, data, dlen,
549: alg, ssh->compat);
1.1 markus 550: }
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