Annotation of src/usr.bin/ssh/ssh_api.c, Revision 1.6
1.6 ! djm 1: /* $OpenBSD: ssh_api.c,v 1.5 2015/12/04 16:41:28 markus 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 "ssh1.h" /* For SSH_MSG_NONE */
19: #include "ssh_api.h"
20: #include "compat.h"
21: #include "log.h"
22: #include "authfile.h"
23: #include "sshkey.h"
24: #include "misc.h"
25: #include "ssh1.h"
26: #include "ssh2.h"
27: #include "version.h"
28: #include "myproposal.h"
29: #include "ssherr.h"
30: #include "sshbuf.h"
31:
32: #include <string.h>
33:
34: int _ssh_exchange_banner(struct ssh *);
35: int _ssh_send_banner(struct ssh *, char **);
36: int _ssh_read_banner(struct ssh *, char **);
37: int _ssh_order_hostkeyalgs(struct ssh *);
38: int _ssh_verify_host_key(struct sshkey *, struct ssh *);
1.2 djm 39: struct sshkey *_ssh_host_public_key(int, int, struct ssh *);
40: struct sshkey *_ssh_host_private_key(int, int, struct ssh *);
1.5 markus 41: int _ssh_host_key_sign(struct sshkey *, struct sshkey *,
42: u_char **, size_t *, const u_char *, size_t, const char *, u_int);
1.1 markus 43:
44: /*
45: * stubs for the server side implementation of kex.
46: * disable privsep so our stubs will never be called.
47: */
48: int use_privsep = 0;
49: int mm_sshkey_sign(struct sshkey *, u_char **, u_int *,
1.5 markus 50: u_char *, u_int, char *, u_int);
1.1 markus 51: DH *mm_choose_dh(int, int, int);
52:
53: /* Define these two variables here so that they are part of the library */
54: u_char *session_id2 = NULL;
55: u_int session_id2_len = 0;
56:
57: int
58: mm_sshkey_sign(struct sshkey *key, u_char **sigp, u_int *lenp,
1.5 markus 59: u_char *data, u_int datalen, char *alg, u_int compat)
1.1 markus 60: {
61: return (-1);
62: }
63:
64: DH *
65: mm_choose_dh(int min, int nbits, int max)
66: {
67: return (NULL);
68: }
69:
70: /* API */
71:
72: int
73: ssh_init(struct ssh **sshp, int is_server, struct kex_params *kex_params)
74: {
75: char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
76: struct ssh *ssh;
77: char **proposal;
78: static int called;
79: int r;
80:
81: if (!called) {
82: OpenSSL_add_all_algorithms();
83: called = 1;
84: }
85:
1.3 djm 86: if ((ssh = ssh_packet_set_connection(NULL, -1, -1)) == NULL)
87: return SSH_ERR_ALLOC_FAIL;
1.1 markus 88: if (is_server)
89: ssh_packet_set_server(ssh);
90:
91: /* Initialize key exchange */
92: proposal = kex_params ? kex_params->proposal : myproposal;
93: if ((r = kex_new(ssh, proposal, &ssh->kex)) != 0) {
94: ssh_free(ssh);
95: return r;
96: }
97: ssh->kex->server = is_server;
98: if (is_server) {
99: #ifdef WITH_OPENSSL
100: ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
101: ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1.6 ! djm 102: ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
! 103: ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
! 104: ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
1.1 markus 105: ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
106: ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
107: ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
108: #endif /* WITH_OPENSSL */
109: ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_server;
110: ssh->kex->load_host_public_key=&_ssh_host_public_key;
111: ssh->kex->load_host_private_key=&_ssh_host_private_key;
112: ssh->kex->sign=&_ssh_host_key_sign;
113: } else {
114: #ifdef WITH_OPENSSL
115: ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
116: ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
1.6 ! djm 117: ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
! 118: ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
! 119: ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
1.1 markus 120: ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
121: ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
122: ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
123: #endif /* WITH_OPENSSL */
124: ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
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;
233: if (ssh->kex->client_version_string == NULL ||
234: ssh->kex->server_version_string == NULL)
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
309: _ssh_read_banner(struct ssh *ssh, char **bannerp)
310: {
311: struct sshbuf *input;
312: const char *s;
313: char buf[256], remote_version[256]; /* must be same size! */
314: const char *mismatch = "Protocol mismatch.\r\n";
315: int r, remote_major, remote_minor;
316: size_t i, n, j, len;
317:
318: *bannerp = NULL;
319: input = ssh_packet_get_input(ssh);
320: len = sshbuf_len(input);
321: s = (const char *)sshbuf_ptr(input);
322: for (j = n = 0;;) {
323: for (i = 0; i < sizeof(buf) - 1; i++) {
324: if (j >= len)
325: return (0);
326: buf[i] = s[j++];
327: if (buf[i] == '\r') {
328: buf[i] = '\n';
329: buf[i + 1] = 0;
330: continue; /**XXX wait for \n */
331: }
332: if (buf[i] == '\n') {
333: buf[i + 1] = 0;
334: break;
335: }
336: }
337: buf[sizeof(buf) - 1] = 0;
338: if (strncmp(buf, "SSH-", 4) == 0)
339: break;
340: debug("ssh_exchange_identification: %s", buf);
341: if (ssh->kex->server || ++n > 65536) {
342: if ((r = sshbuf_put(ssh_packet_get_output(ssh),
343: mismatch, strlen(mismatch))) != 0)
344: return r;
345: return SSH_ERR_NO_PROTOCOL_VERSION;
346: }
347: }
348: if ((r = sshbuf_consume(input, j)) != 0)
349: return r;
350:
351: /*
352: * Check that the versions match. In future this might accept
353: * several versions and set appropriate flags to handle them.
354: */
355: if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
356: &remote_major, &remote_minor, remote_version) != 3)
357: return SSH_ERR_INVALID_FORMAT;
358: debug("Remote protocol version %d.%d, remote software version %.100s",
359: remote_major, remote_minor, remote_version);
360:
361: ssh->compat = compat_datafellows(remote_version);
362: if (remote_major == 1 && remote_minor == 99) {
363: remote_major = 2;
364: remote_minor = 0;
365: }
366: if (remote_major != 2)
367: return SSH_ERR_PROTOCOL_MISMATCH;
368: enable_compat20();
369: chop(buf);
370: debug("Remote version string %.100s", buf);
371: if ((*bannerp = strdup(buf)) == NULL)
372: return SSH_ERR_ALLOC_FAIL;
373: return 0;
374: }
375:
376: /* Send our own protocol version identification. */
377: int
378: _ssh_send_banner(struct ssh *ssh, char **bannerp)
379: {
380: char buf[256];
381: int r;
382:
383: snprintf(buf, sizeof buf, "SSH-2.0-%.100s\r\n", SSH_VERSION);
384: if ((r = sshbuf_put(ssh_packet_get_output(ssh), buf, strlen(buf))) != 0)
385: return r;
386: chop(buf);
387: debug("Local version string %.100s", buf);
388: if ((*bannerp = strdup(buf)) == NULL)
389: return SSH_ERR_ALLOC_FAIL;
390: return 0;
391: }
392:
393: int
394: _ssh_exchange_banner(struct ssh *ssh)
395: {
396: struct kex *kex = ssh->kex;
397: int r;
398:
399: /*
400: * if _ssh_read_banner() cannot parse a full version string
401: * it will return NULL and we end up calling it again.
402: */
403:
404: r = 0;
405: if (kex->server) {
406: if (kex->server_version_string == NULL)
407: r = _ssh_send_banner(ssh, &kex->server_version_string);
408: if (r == 0 &&
409: kex->server_version_string != NULL &&
410: kex->client_version_string == NULL)
411: r = _ssh_read_banner(ssh, &kex->client_version_string);
412: } else {
413: if (kex->server_version_string == NULL)
414: r = _ssh_read_banner(ssh, &kex->server_version_string);
415: if (r == 0 &&
416: kex->server_version_string != NULL &&
417: kex->client_version_string == NULL)
418: r = _ssh_send_banner(ssh, &kex->client_version_string);
419: }
420: if (r != 0)
421: return r;
422: /* start initial kex as soon as we have exchanged the banners */
423: if (kex->server_version_string != NULL &&
424: kex->client_version_string != NULL) {
425: if ((r = _ssh_order_hostkeyalgs(ssh)) != 0 ||
426: (r = kex_send_kexinit(ssh)) != 0)
427: return r;
428: }
429: return 0;
430: }
431:
432: struct sshkey *
1.2 djm 433: _ssh_host_public_key(int type, int nid, struct ssh *ssh)
1.1 markus 434: {
435: struct key_entry *k;
436:
437: debug3("%s: need %d", __func__, type);
438: TAILQ_FOREACH(k, &ssh->public_keys, next) {
439: debug3("%s: check %s", __func__, sshkey_type(k->key));
1.2 djm 440: if (k->key->type == type &&
441: (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
1.1 markus 442: return (k->key);
443: }
444: return (NULL);
445: }
446:
447: struct sshkey *
1.2 djm 448: _ssh_host_private_key(int type, int nid, struct ssh *ssh)
1.1 markus 449: {
450: struct key_entry *k;
451:
452: debug3("%s: need %d", __func__, type);
453: TAILQ_FOREACH(k, &ssh->private_keys, next) {
454: debug3("%s: check %s", __func__, sshkey_type(k->key));
1.2 djm 455: if (k->key->type == type &&
456: (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
1.1 markus 457: return (k->key);
458: }
459: return (NULL);
460: }
461:
462: int
463: _ssh_verify_host_key(struct sshkey *hostkey, struct ssh *ssh)
464: {
465: struct key_entry *k;
466:
467: debug3("%s: need %s", __func__, sshkey_type(hostkey));
468: TAILQ_FOREACH(k, &ssh->public_keys, next) {
469: debug3("%s: check %s", __func__, sshkey_type(k->key));
470: if (sshkey_equal_public(hostkey, k->key))
471: return (0); /* ok */
472: }
473: return (-1); /* failed */
474: }
475:
476: /* offer hostkey algorithms in kexinit depending on registered keys */
477: int
478: _ssh_order_hostkeyalgs(struct ssh *ssh)
479: {
480: struct key_entry *k;
481: char *orig, *avail, *oavail = NULL, *alg, *replace = NULL;
482: char **proposal;
483: size_t maxlen;
484: int ktype, r;
485:
486: /* XXX we de-serialize ssh->kex->my, modify it, and change it */
487: if ((r = kex_buf2prop(ssh->kex->my, NULL, &proposal)) != 0)
488: return r;
489: orig = proposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
490: if ((oavail = avail = strdup(orig)) == NULL) {
491: r = SSH_ERR_ALLOC_FAIL;
492: goto out;
493: }
494: maxlen = strlen(avail) + 1;
495: if ((replace = calloc(1, maxlen)) == NULL) {
496: r = SSH_ERR_ALLOC_FAIL;
497: goto out;
498: }
499: *replace = '\0';
500: while ((alg = strsep(&avail, ",")) && *alg != '\0') {
501: if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
502: continue;
503: TAILQ_FOREACH(k, &ssh->public_keys, next) {
504: if (k->key->type == ktype ||
505: (sshkey_is_cert(k->key) && k->key->type ==
506: sshkey_type_plain(ktype))) {
507: if (*replace != '\0')
508: strlcat(replace, ",", maxlen);
509: strlcat(replace, alg, maxlen);
510: break;
511: }
512: }
513: }
514: if (*replace != '\0') {
515: debug2("%s: orig/%d %s", __func__, ssh->kex->server, orig);
516: debug2("%s: replace/%d %s", __func__, ssh->kex->server, replace);
517: free(orig);
518: proposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = replace;
519: replace = NULL; /* owned by proposal */
520: r = kex_prop2buf(ssh->kex->my, proposal);
521: }
522: out:
523: free(oavail);
524: free(replace);
525: kex_prop_free(proposal);
526: return r;
527: }
528:
529: int
530: _ssh_host_key_sign(struct sshkey *privkey, struct sshkey *pubkey,
1.5 markus 531: u_char **signature, size_t *slen, const u_char *data, size_t dlen,
532: const char *alg, u_int compat)
1.1 markus 533: {
1.5 markus 534: return sshkey_sign(privkey, signature, slen, data, dlen, alg, compat);
1.1 markus 535: }
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