Annotation of src/usr.bin/ssh/ssh_api.c, Revision 1.3
1.3 ! djm 1: /* $OpenBSD: ssh_api.c,v 1.2 2015/01/26 06:10:03 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 "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 *);
1.1 markus 41: int _ssh_host_key_sign(struct sshkey *, struct sshkey *, u_char **,
42: size_t *, u_char *, size_t, u_int);
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 *,
50: u_char *, u_int, u_int);
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,
59: u_char *data, u_int datalen, u_int compat)
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;
102: ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
103: ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
104: ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
105: #endif /* WITH_OPENSSL */
106: ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_server;
107: ssh->kex->load_host_public_key=&_ssh_host_public_key;
108: ssh->kex->load_host_private_key=&_ssh_host_private_key;
109: ssh->kex->sign=&_ssh_host_key_sign;
110: } else {
111: #ifdef WITH_OPENSSL
112: ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
113: ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
114: ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
115: ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
116: ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
117: #endif /* WITH_OPENSSL */
118: ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
119: ssh->kex->verify_host_key =&_ssh_verify_host_key;
120: }
121: *sshp = ssh;
122: return 0;
123: }
124:
125: void
126: ssh_free(struct ssh *ssh)
127: {
128: struct key_entry *k;
129:
130: ssh_packet_close(ssh);
131: /*
132: * we've only created the public keys variants in case we
133: * are a acting as a server.
134: */
135: while ((k = TAILQ_FIRST(&ssh->public_keys)) != NULL) {
136: TAILQ_REMOVE(&ssh->public_keys, k, next);
137: if (ssh->kex && ssh->kex->server)
138: sshkey_free(k->key);
139: free(k);
140: }
141: while ((k = TAILQ_FIRST(&ssh->private_keys)) != NULL) {
142: TAILQ_REMOVE(&ssh->private_keys, k, next);
143: free(k);
144: }
145: if (ssh->kex)
146: kex_free(ssh->kex);
147: free(ssh);
148: }
149:
150: void
151: ssh_set_app_data(struct ssh *ssh, void *app_data)
152: {
153: ssh->app_data = app_data;
154: }
155:
156: void *
157: ssh_get_app_data(struct ssh *ssh)
158: {
159: return ssh->app_data;
160: }
161:
162: /* Returns < 0 on error, 0 otherwise */
163: int
164: ssh_add_hostkey(struct ssh *ssh, struct sshkey *key)
165: {
166: struct sshkey *pubkey = NULL;
167: struct key_entry *k = NULL, *k_prv = NULL;
168: int r;
169:
170: if (ssh->kex->server) {
171: if ((r = sshkey_from_private(key, &pubkey)) != 0)
172: return r;
173: if ((k = malloc(sizeof(*k))) == NULL ||
174: (k_prv = malloc(sizeof(*k_prv))) == NULL) {
175: free(k);
176: sshkey_free(pubkey);
177: return SSH_ERR_ALLOC_FAIL;
178: }
179: k_prv->key = key;
180: TAILQ_INSERT_TAIL(&ssh->private_keys, k_prv, next);
181:
182: /* add the public key, too */
183: k->key = pubkey;
184: TAILQ_INSERT_TAIL(&ssh->public_keys, k, next);
185: r = 0;
186: } else {
187: if ((k = malloc(sizeof(*k))) == NULL)
188: return SSH_ERR_ALLOC_FAIL;
189: k->key = key;
190: TAILQ_INSERT_TAIL(&ssh->public_keys, k, next);
191: r = 0;
192: }
193:
194: return r;
195: }
196:
197: int
198: ssh_set_verify_host_key_callback(struct ssh *ssh,
199: int (*cb)(struct sshkey *, struct ssh *))
200: {
201: if (cb == NULL || ssh->kex == NULL)
202: return SSH_ERR_INVALID_ARGUMENT;
203:
204: ssh->kex->verify_host_key = cb;
205:
206: return 0;
207: }
208:
209: int
210: ssh_input_append(struct ssh *ssh, const u_char *data, size_t len)
211: {
212: return sshbuf_put(ssh_packet_get_input(ssh), data, len);
213: }
214:
215: int
216: ssh_packet_next(struct ssh *ssh, u_char *typep)
217: {
218: int r;
219: u_int32_t seqnr;
220: u_char type;
221:
222: /*
223: * Try to read a packet. Return SSH_MSG_NONE if no packet or not
224: * enough data.
225: */
226: *typep = SSH_MSG_NONE;
227: if (ssh->kex->client_version_string == NULL ||
228: ssh->kex->server_version_string == NULL)
229: return _ssh_exchange_banner(ssh);
230: /*
231: * If we enough data and a dispatch function then
232: * call the function and get the next packet.
233: * Otherwise return the packet type to the caller so it
234: * can decide how to go on.
235: *
236: * We will only call the dispatch function for:
237: * 20-29 Algorithm negotiation
238: * 30-49 Key exchange method specific (numbers can be reused for
239: * different authentication methods)
240: */
241: for (;;) {
242: if ((r = ssh_packet_read_poll2(ssh, &type, &seqnr)) != 0)
243: return r;
244: if (type > 0 && type < DISPATCH_MAX &&
245: type >= SSH2_MSG_KEXINIT && type <= SSH2_MSG_TRANSPORT_MAX &&
246: ssh->dispatch[type] != NULL) {
247: if ((r = (*ssh->dispatch[type])(type, seqnr, ssh)) != 0)
248: return r;
249: } else {
250: *typep = type;
251: return 0;
252: }
253: }
254: }
255:
256: const u_char *
257: ssh_packet_payload(struct ssh *ssh, size_t *lenp)
258: {
259: return sshpkt_ptr(ssh, lenp);
260: }
261:
262: int
263: ssh_packet_put(struct ssh *ssh, int type, const u_char *data, size_t len)
264: {
265: int r;
266:
267: if ((r = sshpkt_start(ssh, type)) != 0 ||
268: (r = sshpkt_put(ssh, data, len)) != 0 ||
269: (r = sshpkt_send(ssh)) != 0)
270: return r;
271: return 0;
272: }
273:
274: const u_char *
275: ssh_output_ptr(struct ssh *ssh, size_t *len)
276: {
277: struct sshbuf *output = ssh_packet_get_output(ssh);
278:
279: *len = sshbuf_len(output);
280: return sshbuf_ptr(output);
281: }
282:
283: int
284: ssh_output_consume(struct ssh *ssh, size_t len)
285: {
286: return sshbuf_consume(ssh_packet_get_output(ssh), len);
287: }
288:
289: int
290: ssh_output_space(struct ssh *ssh, size_t len)
291: {
292: return (0 == sshbuf_check_reserve(ssh_packet_get_output(ssh), len));
293: }
294:
295: int
296: ssh_input_space(struct ssh *ssh, size_t len)
297: {
298: return (0 == sshbuf_check_reserve(ssh_packet_get_input(ssh), len));
299: }
300:
301: /* Read other side's version identification. */
302: int
303: _ssh_read_banner(struct ssh *ssh, char **bannerp)
304: {
305: struct sshbuf *input;
306: const char *s;
307: char buf[256], remote_version[256]; /* must be same size! */
308: const char *mismatch = "Protocol mismatch.\r\n";
309: int r, remote_major, remote_minor;
310: size_t i, n, j, len;
311:
312: *bannerp = NULL;
313: input = ssh_packet_get_input(ssh);
314: len = sshbuf_len(input);
315: s = (const char *)sshbuf_ptr(input);
316: for (j = n = 0;;) {
317: for (i = 0; i < sizeof(buf) - 1; i++) {
318: if (j >= len)
319: return (0);
320: buf[i] = s[j++];
321: if (buf[i] == '\r') {
322: buf[i] = '\n';
323: buf[i + 1] = 0;
324: continue; /**XXX wait for \n */
325: }
326: if (buf[i] == '\n') {
327: buf[i + 1] = 0;
328: break;
329: }
330: }
331: buf[sizeof(buf) - 1] = 0;
332: if (strncmp(buf, "SSH-", 4) == 0)
333: break;
334: debug("ssh_exchange_identification: %s", buf);
335: if (ssh->kex->server || ++n > 65536) {
336: if ((r = sshbuf_put(ssh_packet_get_output(ssh),
337: mismatch, strlen(mismatch))) != 0)
338: return r;
339: return SSH_ERR_NO_PROTOCOL_VERSION;
340: }
341: }
342: if ((r = sshbuf_consume(input, j)) != 0)
343: return r;
344:
345: /*
346: * Check that the versions match. In future this might accept
347: * several versions and set appropriate flags to handle them.
348: */
349: if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
350: &remote_major, &remote_minor, remote_version) != 3)
351: return SSH_ERR_INVALID_FORMAT;
352: debug("Remote protocol version %d.%d, remote software version %.100s",
353: remote_major, remote_minor, remote_version);
354:
355: ssh->compat = compat_datafellows(remote_version);
356: if (remote_major == 1 && remote_minor == 99) {
357: remote_major = 2;
358: remote_minor = 0;
359: }
360: if (remote_major != 2)
361: return SSH_ERR_PROTOCOL_MISMATCH;
362: enable_compat20();
363: chop(buf);
364: debug("Remote version string %.100s", buf);
365: if ((*bannerp = strdup(buf)) == NULL)
366: return SSH_ERR_ALLOC_FAIL;
367: return 0;
368: }
369:
370: /* Send our own protocol version identification. */
371: int
372: _ssh_send_banner(struct ssh *ssh, char **bannerp)
373: {
374: char buf[256];
375: int r;
376:
377: snprintf(buf, sizeof buf, "SSH-2.0-%.100s\r\n", SSH_VERSION);
378: if ((r = sshbuf_put(ssh_packet_get_output(ssh), buf, strlen(buf))) != 0)
379: return r;
380: chop(buf);
381: debug("Local version string %.100s", buf);
382: if ((*bannerp = strdup(buf)) == NULL)
383: return SSH_ERR_ALLOC_FAIL;
384: return 0;
385: }
386:
387: int
388: _ssh_exchange_banner(struct ssh *ssh)
389: {
390: struct kex *kex = ssh->kex;
391: int r;
392:
393: /*
394: * if _ssh_read_banner() cannot parse a full version string
395: * it will return NULL and we end up calling it again.
396: */
397:
398: r = 0;
399: if (kex->server) {
400: if (kex->server_version_string == NULL)
401: r = _ssh_send_banner(ssh, &kex->server_version_string);
402: if (r == 0 &&
403: kex->server_version_string != NULL &&
404: kex->client_version_string == NULL)
405: r = _ssh_read_banner(ssh, &kex->client_version_string);
406: } else {
407: if (kex->server_version_string == NULL)
408: r = _ssh_read_banner(ssh, &kex->server_version_string);
409: if (r == 0 &&
410: kex->server_version_string != NULL &&
411: kex->client_version_string == NULL)
412: r = _ssh_send_banner(ssh, &kex->client_version_string);
413: }
414: if (r != 0)
415: return r;
416: /* start initial kex as soon as we have exchanged the banners */
417: if (kex->server_version_string != NULL &&
418: kex->client_version_string != NULL) {
419: if ((r = _ssh_order_hostkeyalgs(ssh)) != 0 ||
420: (r = kex_send_kexinit(ssh)) != 0)
421: return r;
422: }
423: return 0;
424: }
425:
426: struct sshkey *
1.2 djm 427: _ssh_host_public_key(int type, int nid, struct ssh *ssh)
1.1 markus 428: {
429: struct key_entry *k;
430:
431: debug3("%s: need %d", __func__, type);
432: TAILQ_FOREACH(k, &ssh->public_keys, next) {
433: debug3("%s: check %s", __func__, sshkey_type(k->key));
1.2 djm 434: if (k->key->type == type &&
435: (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
1.1 markus 436: return (k->key);
437: }
438: return (NULL);
439: }
440:
441: struct sshkey *
1.2 djm 442: _ssh_host_private_key(int type, int nid, struct ssh *ssh)
1.1 markus 443: {
444: struct key_entry *k;
445:
446: debug3("%s: need %d", __func__, type);
447: TAILQ_FOREACH(k, &ssh->private_keys, next) {
448: debug3("%s: check %s", __func__, sshkey_type(k->key));
1.2 djm 449: if (k->key->type == type &&
450: (type != KEY_ECDSA || k->key->ecdsa_nid == nid))
1.1 markus 451: return (k->key);
452: }
453: return (NULL);
454: }
455:
456: int
457: _ssh_verify_host_key(struct sshkey *hostkey, struct ssh *ssh)
458: {
459: struct key_entry *k;
460:
461: debug3("%s: need %s", __func__, sshkey_type(hostkey));
462: TAILQ_FOREACH(k, &ssh->public_keys, next) {
463: debug3("%s: check %s", __func__, sshkey_type(k->key));
464: if (sshkey_equal_public(hostkey, k->key))
465: return (0); /* ok */
466: }
467: return (-1); /* failed */
468: }
469:
470: /* offer hostkey algorithms in kexinit depending on registered keys */
471: int
472: _ssh_order_hostkeyalgs(struct ssh *ssh)
473: {
474: struct key_entry *k;
475: char *orig, *avail, *oavail = NULL, *alg, *replace = NULL;
476: char **proposal;
477: size_t maxlen;
478: int ktype, r;
479:
480: /* XXX we de-serialize ssh->kex->my, modify it, and change it */
481: if ((r = kex_buf2prop(ssh->kex->my, NULL, &proposal)) != 0)
482: return r;
483: orig = proposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
484: if ((oavail = avail = strdup(orig)) == NULL) {
485: r = SSH_ERR_ALLOC_FAIL;
486: goto out;
487: }
488: maxlen = strlen(avail) + 1;
489: if ((replace = calloc(1, maxlen)) == NULL) {
490: r = SSH_ERR_ALLOC_FAIL;
491: goto out;
492: }
493: *replace = '\0';
494: while ((alg = strsep(&avail, ",")) && *alg != '\0') {
495: if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
496: continue;
497: TAILQ_FOREACH(k, &ssh->public_keys, next) {
498: if (k->key->type == ktype ||
499: (sshkey_is_cert(k->key) && k->key->type ==
500: sshkey_type_plain(ktype))) {
501: if (*replace != '\0')
502: strlcat(replace, ",", maxlen);
503: strlcat(replace, alg, maxlen);
504: break;
505: }
506: }
507: }
508: if (*replace != '\0') {
509: debug2("%s: orig/%d %s", __func__, ssh->kex->server, orig);
510: debug2("%s: replace/%d %s", __func__, ssh->kex->server, replace);
511: free(orig);
512: proposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = replace;
513: replace = NULL; /* owned by proposal */
514: r = kex_prop2buf(ssh->kex->my, proposal);
515: }
516: out:
517: free(oavail);
518: free(replace);
519: kex_prop_free(proposal);
520: return r;
521: }
522:
523: int
524: _ssh_host_key_sign(struct sshkey *privkey, struct sshkey *pubkey,
525: u_char **signature, size_t *slen, u_char *data, size_t dlen, u_int compat)
526: {
527: return sshkey_sign(privkey, signature, slen, data, dlen, compat);
528: }
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