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1 | /* | |
2 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
26 | RCSID("$OpenBSD: sshconnect2.c,v 1.29 2000/11/23 21:03:47 markus Exp $"); | |
27 | ||
28 | #include <openssl/bn.h> | |
29 | #include <openssl/rsa.h> | |
30 | #include <openssl/dsa.h> | |
31 | #include <openssl/md5.h> | |
32 | #include <openssl/dh.h> | |
33 | #include <openssl/hmac.h> | |
34 | ||
35 | #include "ssh.h" | |
36 | #include "xmalloc.h" | |
37 | #include "rsa.h" | |
38 | #include "buffer.h" | |
39 | #include "packet.h" | |
40 | #include "uidswap.h" | |
41 | #include "compat.h" | |
42 | #include "readconf.h" | |
43 | #include "bufaux.h" | |
44 | #include "ssh2.h" | |
45 | #include "kex.h" | |
46 | #include "myproposal.h" | |
47 | #include "key.h" | |
48 | #include "sshconnect.h" | |
49 | #include "authfile.h" | |
50 | #include "cli.h" | |
51 | #include "dispatch.h" | |
52 | #include "authfd.h" | |
53 | ||
54 | void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); | |
55 | void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); | |
56 | ||
57 | /* import */ | |
58 | extern char *client_version_string; | |
59 | extern char *server_version_string; | |
60 | extern Options options; | |
61 | ||
62 | /* | |
63 | * SSH2 key exchange | |
64 | */ | |
65 | ||
66 | unsigned char *session_id2 = NULL; | |
67 | int session_id2_len = 0; | |
68 | ||
69 | void | |
70 | ssh_kex2(char *host, struct sockaddr *hostaddr) | |
71 | { | |
72 | int i, plen; | |
73 | Kex *kex; | |
74 | Buffer *client_kexinit, *server_kexinit; | |
75 | char *sprop[PROPOSAL_MAX]; | |
76 | ||
77 | if (options.ciphers == (char *)-1) { | |
78 | log("No valid ciphers for protocol version 2 given, using defaults."); | |
79 | options.ciphers = NULL; | |
80 | } | |
81 | if (options.ciphers != NULL) { | |
82 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
83 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
84 | } | |
85 | if (options.compression) { | |
86 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib"; | |
87 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; | |
88 | } else { | |
89 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none"; | |
90 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
91 | } | |
92 | ||
93 | /* buffers with raw kexinit messages */ | |
94 | server_kexinit = xmalloc(sizeof(*server_kexinit)); | |
95 | buffer_init(server_kexinit); | |
96 | client_kexinit = kex_init(myproposal); | |
97 | ||
98 | /* algorithm negotiation */ | |
99 | kex_exchange_kexinit(client_kexinit, server_kexinit, sprop); | |
100 | kex = kex_choose_conf(myproposal, sprop, 0); | |
101 | for (i = 0; i < PROPOSAL_MAX; i++) | |
102 | xfree(sprop[i]); | |
103 | ||
104 | /* server authentication and session key agreement */ | |
105 | switch(kex->kex_type) { | |
106 | case DH_GRP1_SHA1: | |
107 | ssh_dh1_client(kex, host, hostaddr, | |
108 | client_kexinit, server_kexinit); | |
109 | break; | |
110 | case DH_GEX_SHA1: | |
111 | ssh_dhgex_client(kex, host, hostaddr, client_kexinit, | |
112 | server_kexinit); | |
113 | break; | |
114 | default: | |
115 | fatal("Unsupported key exchange %d", kex->kex_type); | |
116 | } | |
117 | ||
118 | buffer_free(client_kexinit); | |
119 | buffer_free(server_kexinit); | |
120 | xfree(client_kexinit); | |
121 | xfree(server_kexinit); | |
122 | ||
123 | debug("Wait SSH2_MSG_NEWKEYS."); | |
124 | packet_read_expect(&plen, SSH2_MSG_NEWKEYS); | |
125 | packet_done(); | |
126 | debug("GOT SSH2_MSG_NEWKEYS."); | |
127 | ||
128 | debug("send SSH2_MSG_NEWKEYS."); | |
129 | packet_start(SSH2_MSG_NEWKEYS); | |
130 | packet_send(); | |
131 | packet_write_wait(); | |
132 | debug("done: send SSH2_MSG_NEWKEYS."); | |
133 | ||
134 | #ifdef DEBUG_KEXDH | |
135 | /* send 1st encrypted/maced/compressed message */ | |
136 | packet_start(SSH2_MSG_IGNORE); | |
137 | packet_put_cstring("markus"); | |
138 | packet_send(); | |
139 | packet_write_wait(); | |
140 | #endif | |
141 | debug("done: KEX2."); | |
142 | } | |
143 | ||
144 | /* diffie-hellman-group1-sha1 */ | |
145 | ||
146 | void | |
147 | ssh_dh1_client(Kex *kex, char *host, struct sockaddr *hostaddr, | |
148 | Buffer *client_kexinit, Buffer *server_kexinit) | |
149 | { | |
150 | #ifdef DEBUG_KEXDH | |
151 | int i; | |
152 | #endif | |
153 | int plen, dlen; | |
154 | unsigned int klen, kout; | |
155 | char *signature = NULL; | |
156 | unsigned int slen; | |
157 | char *server_host_key_blob = NULL; | |
158 | Key *server_host_key; | |
159 | unsigned int sbloblen; | |
160 | DH *dh; | |
161 | BIGNUM *dh_server_pub = 0; | |
162 | BIGNUM *shared_secret = 0; | |
163 | unsigned char *kbuf; | |
164 | unsigned char *hash; | |
165 | ||
166 | debug("Sending SSH2_MSG_KEXDH_INIT."); | |
167 | /* generate and send 'e', client DH public key */ | |
168 | dh = dh_new_group1(); | |
169 | packet_start(SSH2_MSG_KEXDH_INIT); | |
170 | packet_put_bignum2(dh->pub_key); | |
171 | packet_send(); | |
172 | packet_write_wait(); | |
173 | ||
174 | #ifdef DEBUG_KEXDH | |
175 | fprintf(stderr, "\np= "); | |
176 | BN_print_fp(stderr, dh->p); | |
177 | fprintf(stderr, "\ng= "); | |
178 | BN_print_fp(stderr, dh->g); | |
179 | fprintf(stderr, "\npub= "); | |
180 | BN_print_fp(stderr, dh->pub_key); | |
181 | fprintf(stderr, "\n"); | |
182 | DHparams_print_fp(stderr, dh); | |
183 | #endif | |
184 | ||
185 | debug("Wait SSH2_MSG_KEXDH_REPLY."); | |
186 | ||
187 | packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY); | |
188 | ||
189 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
190 | ||
191 | /* key, cert */ | |
192 | server_host_key_blob = packet_get_string(&sbloblen); | |
193 | server_host_key = key_from_blob(server_host_key_blob, sbloblen); | |
194 | if (server_host_key == NULL) | |
195 | fatal("cannot decode server_host_key_blob"); | |
196 | ||
197 | check_host_key(host, hostaddr, server_host_key, | |
198 | options.user_hostfile2, options.system_hostfile2); | |
199 | ||
200 | /* DH paramter f, server public DH key */ | |
201 | dh_server_pub = BN_new(); | |
202 | if (dh_server_pub == NULL) | |
203 | fatal("dh_server_pub == NULL"); | |
204 | packet_get_bignum2(dh_server_pub, &dlen); | |
205 | ||
206 | #ifdef DEBUG_KEXDH | |
207 | fprintf(stderr, "\ndh_server_pub= "); | |
208 | BN_print_fp(stderr, dh_server_pub); | |
209 | fprintf(stderr, "\n"); | |
210 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
211 | #endif | |
212 | ||
213 | /* signed H */ | |
214 | signature = packet_get_string(&slen); | |
215 | packet_done(); | |
216 | ||
217 | if (!dh_pub_is_valid(dh, dh_server_pub)) | |
218 | packet_disconnect("bad server public DH value"); | |
219 | ||
220 | klen = DH_size(dh); | |
221 | kbuf = xmalloc(klen); | |
222 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
223 | #ifdef DEBUG_KEXDH | |
224 | debug("shared secret: len %d/%d", klen, kout); | |
225 | fprintf(stderr, "shared secret == "); | |
226 | for (i = 0; i< kout; i++) | |
227 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
228 | fprintf(stderr, "\n"); | |
229 | #endif | |
230 | shared_secret = BN_new(); | |
231 | ||
232 | BN_bin2bn(kbuf, kout, shared_secret); | |
233 | memset(kbuf, 0, klen); | |
234 | xfree(kbuf); | |
235 | ||
236 | /* calc and verify H */ | |
237 | hash = kex_hash( | |
238 | client_version_string, | |
239 | server_version_string, | |
240 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
241 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
242 | server_host_key_blob, sbloblen, | |
243 | dh->pub_key, | |
244 | dh_server_pub, | |
245 | shared_secret | |
246 | ); | |
247 | xfree(server_host_key_blob); | |
248 | DH_free(dh); | |
249 | #ifdef DEBUG_KEXDH | |
250 | fprintf(stderr, "hash == "); | |
251 | for (i = 0; i< 20; i++) | |
252 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
253 | fprintf(stderr, "\n"); | |
254 | #endif | |
255 | if (key_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1) | |
256 | fatal("key_verify failed for server_host_key"); | |
257 | key_free(server_host_key); | |
258 | ||
259 | kex_derive_keys(kex, hash, shared_secret); | |
260 | packet_set_kex(kex); | |
261 | ||
262 | /* save session id */ | |
263 | session_id2_len = 20; | |
264 | session_id2 = xmalloc(session_id2_len); | |
265 | memcpy(session_id2, hash, session_id2_len); | |
266 | } | |
267 | ||
268 | /* diffie-hellman-group-exchange-sha1 */ | |
269 | ||
270 | /* | |
271 | * Estimates the group order for a Diffie-Hellman group that has an | |
272 | * attack complexity approximately the same as O(2**bits). Estimate | |
273 | * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))) | |
274 | */ | |
275 | ||
276 | int | |
277 | dh_estimate(int bits) | |
278 | { | |
279 | ||
280 | if (bits < 64) | |
281 | return (512); /* O(2**63) */ | |
282 | if (bits < 128) | |
283 | return (1024); /* O(2**86) */ | |
284 | if (bits < 192) | |
285 | return (2048); /* O(2**116) */ | |
286 | return (4096); /* O(2**156) */ | |
287 | } | |
288 | ||
289 | void | |
290 | ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr, | |
291 | Buffer *client_kexinit, Buffer *server_kexinit) | |
292 | { | |
293 | #ifdef DEBUG_KEXDH | |
294 | int i; | |
295 | #endif | |
296 | int plen, dlen; | |
297 | unsigned int klen, kout; | |
298 | char *signature = NULL; | |
299 | unsigned int slen, nbits; | |
300 | char *server_host_key_blob = NULL; | |
301 | Key *server_host_key; | |
302 | unsigned int sbloblen; | |
303 | DH *dh; | |
304 | BIGNUM *dh_server_pub = 0; | |
305 | BIGNUM *shared_secret = 0; | |
306 | BIGNUM *p = 0, *g = 0; | |
307 | unsigned char *kbuf; | |
308 | unsigned char *hash; | |
309 | ||
310 | nbits = dh_estimate(kex->enc[MODE_OUT].cipher->key_len * 8); | |
311 | ||
312 | debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST."); | |
313 | packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST); | |
314 | packet_put_int(nbits); | |
315 | packet_send(); | |
316 | packet_write_wait(); | |
317 | ||
318 | #ifdef DEBUG_KEXDH | |
319 | fprintf(stderr, "\nnbits = %d", nbits); | |
320 | #endif | |
321 | ||
322 | debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP."); | |
323 | ||
324 | packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP); | |
325 | ||
326 | debug("Got SSH2_MSG_KEX_DH_GEX_GROUP."); | |
327 | ||
328 | if ((p = BN_new()) == NULL) | |
329 | fatal("BN_new"); | |
330 | packet_get_bignum2(p, &dlen); | |
331 | if ((g = BN_new()) == NULL) | |
332 | fatal("BN_new"); | |
333 | packet_get_bignum2(g, &dlen); | |
334 | if ((dh = dh_new_group(g, p)) == NULL) | |
335 | fatal("dh_new_group"); | |
336 | ||
337 | #ifdef DEBUG_KEXDH | |
338 | fprintf(stderr, "\np= "); | |
339 | BN_print_fp(stderr, dh->p); | |
340 | fprintf(stderr, "\ng= "); | |
341 | BN_print_fp(stderr, dh->g); | |
342 | fprintf(stderr, "\npub= "); | |
343 | BN_print_fp(stderr, dh->pub_key); | |
344 | fprintf(stderr, "\n"); | |
345 | DHparams_print_fp(stderr, dh); | |
346 | #endif | |
347 | ||
348 | debug("Sending SSH2_MSG_KEX_DH_GEX_INIT."); | |
349 | /* generate and send 'e', client DH public key */ | |
350 | packet_start(SSH2_MSG_KEX_DH_GEX_INIT); | |
351 | packet_put_bignum2(dh->pub_key); | |
352 | packet_send(); | |
353 | packet_write_wait(); | |
354 | ||
355 | debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY."); | |
356 | ||
357 | packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY); | |
358 | ||
359 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
360 | ||
361 | /* key, cert */ | |
362 | server_host_key_blob = packet_get_string(&sbloblen); | |
363 | server_host_key = key_from_blob(server_host_key_blob, sbloblen); | |
364 | if (server_host_key == NULL) | |
365 | fatal("cannot decode server_host_key_blob"); | |
366 | ||
367 | check_host_key(host, hostaddr, server_host_key, | |
368 | options.user_hostfile2, options.system_hostfile2); | |
369 | ||
370 | /* DH paramter f, server public DH key */ | |
371 | dh_server_pub = BN_new(); | |
372 | if (dh_server_pub == NULL) | |
373 | fatal("dh_server_pub == NULL"); | |
374 | packet_get_bignum2(dh_server_pub, &dlen); | |
375 | ||
376 | #ifdef DEBUG_KEXDH | |
377 | fprintf(stderr, "\ndh_server_pub= "); | |
378 | BN_print_fp(stderr, dh_server_pub); | |
379 | fprintf(stderr, "\n"); | |
380 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
381 | #endif | |
382 | ||
383 | /* signed H */ | |
384 | signature = packet_get_string(&slen); | |
385 | packet_done(); | |
386 | ||
387 | if (!dh_pub_is_valid(dh, dh_server_pub)) | |
388 | packet_disconnect("bad server public DH value"); | |
389 | ||
390 | klen = DH_size(dh); | |
391 | kbuf = xmalloc(klen); | |
392 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
393 | #ifdef DEBUG_KEXDH | |
394 | debug("shared secret: len %d/%d", klen, kout); | |
395 | fprintf(stderr, "shared secret == "); | |
396 | for (i = 0; i< kout; i++) | |
397 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
398 | fprintf(stderr, "\n"); | |
399 | #endif | |
400 | shared_secret = BN_new(); | |
401 | ||
402 | BN_bin2bn(kbuf, kout, shared_secret); | |
403 | memset(kbuf, 0, klen); | |
404 | xfree(kbuf); | |
405 | ||
406 | /* calc and verify H */ | |
407 | hash = kex_hash_gex( | |
408 | client_version_string, | |
409 | server_version_string, | |
410 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
411 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
412 | server_host_key_blob, sbloblen, | |
413 | nbits, dh->p, dh->g, | |
414 | dh->pub_key, | |
415 | dh_server_pub, | |
416 | shared_secret | |
417 | ); | |
418 | xfree(server_host_key_blob); | |
419 | DH_free(dh); | |
420 | #ifdef DEBUG_KEXDH | |
421 | fprintf(stderr, "hash == "); | |
422 | for (i = 0; i< 20; i++) | |
423 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
424 | fprintf(stderr, "\n"); | |
425 | #endif | |
426 | if (key_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1) | |
427 | fatal("key_verify failed for server_host_key"); | |
428 | key_free(server_host_key); | |
429 | ||
430 | kex_derive_keys(kex, hash, shared_secret); | |
431 | packet_set_kex(kex); | |
432 | ||
433 | /* save session id */ | |
434 | session_id2_len = 20; | |
435 | session_id2 = xmalloc(session_id2_len); | |
436 | memcpy(session_id2, hash, session_id2_len); | |
437 | } | |
438 | ||
439 | /* | |
440 | * Authenticate user | |
441 | */ | |
442 | ||
443 | typedef struct Authctxt Authctxt; | |
444 | typedef struct Authmethod Authmethod; | |
445 | ||
446 | typedef int sign_cb_fn( | |
447 | Authctxt *authctxt, Key *key, | |
448 | unsigned char **sigp, int *lenp, unsigned char *data, int datalen); | |
449 | ||
450 | struct Authctxt { | |
451 | const char *server_user; | |
452 | const char *host; | |
453 | const char *service; | |
454 | AuthenticationConnection *agent; | |
455 | Authmethod *method; | |
456 | int success; | |
457 | }; | |
458 | struct Authmethod { | |
459 | char *name; /* string to compare against server's list */ | |
460 | int (*userauth)(Authctxt *authctxt); | |
461 | int *enabled; /* flag in option struct that enables method */ | |
462 | int *batch_flag; /* flag in option struct that disables method */ | |
463 | }; | |
464 | ||
465 | void input_userauth_success(int type, int plen, void *ctxt); | |
466 | void input_userauth_failure(int type, int plen, void *ctxt); | |
467 | void input_userauth_error(int type, int plen, void *ctxt); | |
468 | void input_userauth_info_req(int type, int plen, void *ctxt); | |
469 | ||
470 | int userauth_none(Authctxt *authctxt); | |
471 | int userauth_pubkey(Authctxt *authctxt); | |
472 | int userauth_passwd(Authctxt *authctxt); | |
473 | int userauth_kbdint(Authctxt *authctxt); | |
474 | ||
475 | void authmethod_clear(); | |
476 | Authmethod *authmethod_get(char *authlist); | |
477 | Authmethod *authmethod_lookup(const char *name); | |
478 | ||
479 | Authmethod authmethods[] = { | |
480 | {"publickey", | |
481 | userauth_pubkey, | |
482 | &options.pubkey_authentication, | |
483 | NULL}, | |
484 | {"password", | |
485 | userauth_passwd, | |
486 | &options.password_authentication, | |
487 | &options.batch_mode}, | |
488 | {"keyboard-interactive", | |
489 | userauth_kbdint, | |
490 | &options.kbd_interactive_authentication, | |
491 | &options.batch_mode}, | |
492 | {"none", | |
493 | userauth_none, | |
494 | NULL, | |
495 | NULL}, | |
496 | {NULL, NULL, NULL, NULL} | |
497 | }; | |
498 | ||
499 | void | |
500 | ssh_userauth2(const char *server_user, char *host) | |
501 | { | |
502 | Authctxt authctxt; | |
503 | int type; | |
504 | int plen; | |
505 | ||
506 | debug("send SSH2_MSG_SERVICE_REQUEST"); | |
507 | packet_start(SSH2_MSG_SERVICE_REQUEST); | |
508 | packet_put_cstring("ssh-userauth"); | |
509 | packet_send(); | |
510 | packet_write_wait(); | |
511 | type = packet_read(&plen); | |
512 | if (type != SSH2_MSG_SERVICE_ACCEPT) { | |
513 | fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); | |
514 | } | |
515 | if (packet_remaining() > 0) { | |
516 | char *reply = packet_get_string(&plen); | |
517 | debug("service_accept: %s", reply); | |
518 | xfree(reply); | |
519 | packet_done(); | |
520 | } else { | |
521 | debug("buggy server: service_accept w/o service"); | |
522 | } | |
523 | packet_done(); | |
524 | debug("got SSH2_MSG_SERVICE_ACCEPT"); | |
525 | ||
526 | /* setup authentication context */ | |
527 | authctxt.agent = ssh_get_authentication_connection(); | |
528 | authctxt.server_user = server_user; | |
529 | authctxt.host = host; | |
530 | authctxt.service = "ssh-connection"; /* service name */ | |
531 | authctxt.success = 0; | |
532 | authctxt.method = authmethod_lookup("none"); | |
533 | if (authctxt.method == NULL) | |
534 | fatal("ssh_userauth2: internal error: cannot send userauth none request"); | |
535 | authmethod_clear(); | |
536 | ||
537 | /* initial userauth request */ | |
538 | userauth_none(&authctxt); | |
539 | ||
540 | dispatch_init(&input_userauth_error); | |
541 | dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); | |
542 | dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); | |
543 | dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ | |
544 | ||
545 | if (authctxt.agent != NULL) | |
546 | ssh_close_authentication_connection(authctxt.agent); | |
547 | ||
548 | debug("ssh-userauth2 successfull: method %s", authctxt.method->name); | |
549 | } | |
550 | void | |
551 | input_userauth_error(int type, int plen, void *ctxt) | |
552 | { | |
553 | fatal("input_userauth_error: bad message during authentication"); | |
554 | } | |
555 | void | |
556 | input_userauth_success(int type, int plen, void *ctxt) | |
557 | { | |
558 | Authctxt *authctxt = ctxt; | |
559 | if (authctxt == NULL) | |
560 | fatal("input_userauth_success: no authentication context"); | |
561 | authctxt->success = 1; /* break out */ | |
562 | } | |
563 | void | |
564 | input_userauth_failure(int type, int plen, void *ctxt) | |
565 | { | |
566 | Authmethod *method = NULL; | |
567 | Authctxt *authctxt = ctxt; | |
568 | char *authlist = NULL; | |
569 | int partial; | |
570 | ||
571 | if (authctxt == NULL) | |
572 | fatal("input_userauth_failure: no authentication context"); | |
573 | ||
574 | authlist = packet_get_string(NULL); | |
575 | partial = packet_get_char(); | |
576 | packet_done(); | |
577 | ||
578 | if (partial != 0) | |
579 | debug("partial success"); | |
580 | debug("authentications that can continue: %s", authlist); | |
581 | ||
582 | for (;;) { | |
583 | method = authmethod_get(authlist); | |
584 | if (method == NULL) | |
585 | fatal("Unable to find an authentication method"); | |
586 | authctxt->method = method; | |
587 | if (method->userauth(authctxt) != 0) { | |
588 | debug2("we sent a %s packet, wait for reply", method->name); | |
589 | break; | |
590 | } else { | |
591 | debug2("we did not send a packet, disable method"); | |
592 | method->enabled = NULL; | |
593 | } | |
594 | } | |
595 | xfree(authlist); | |
596 | } | |
597 | ||
598 | int | |
599 | userauth_none(Authctxt *authctxt) | |
600 | { | |
601 | /* initial userauth request */ | |
602 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
603 | packet_put_cstring(authctxt->server_user); | |
604 | packet_put_cstring(authctxt->service); | |
605 | packet_put_cstring(authctxt->method->name); | |
606 | packet_send(); | |
607 | packet_write_wait(); | |
608 | return 1; | |
609 | } | |
610 | ||
611 | int | |
612 | userauth_passwd(Authctxt *authctxt) | |
613 | { | |
614 | static int attempt = 0; | |
615 | char prompt[80]; | |
616 | char *password; | |
617 | ||
618 | if (attempt++ >= options.number_of_password_prompts) | |
619 | return 0; | |
620 | ||
621 | if(attempt != 1) | |
622 | error("Permission denied, please try again."); | |
623 | ||
624 | snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ", | |
625 | authctxt->server_user, authctxt->host); | |
626 | password = read_passphrase(prompt, 0); | |
627 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
628 | packet_put_cstring(authctxt->server_user); | |
629 | packet_put_cstring(authctxt->service); | |
630 | packet_put_cstring(authctxt->method->name); | |
631 | packet_put_char(0); | |
632 | packet_put_cstring(password); | |
633 | memset(password, 0, strlen(password)); | |
634 | xfree(password); | |
635 | packet_send(); | |
636 | packet_write_wait(); | |
637 | return 1; | |
638 | } | |
639 | ||
640 | int | |
641 | sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) | |
642 | { | |
643 | Buffer b; | |
644 | unsigned char *blob, *signature; | |
645 | int bloblen, slen; | |
646 | int skip = 0; | |
647 | int ret = -1; | |
648 | int have_sig = 1; | |
649 | ||
650 | if (key_to_blob(k, &blob, &bloblen) == 0) { | |
651 | /* we cannot handle this key */ | |
652 | return 0; | |
653 | } | |
654 | /* data to be signed */ | |
655 | buffer_init(&b); | |
656 | if (datafellows & SSH_OLD_SESSIONID) { | |
657 | buffer_append(&b, session_id2, session_id2_len); | |
658 | skip = session_id2_len; | |
659 | } else { | |
660 | buffer_put_string(&b, session_id2, session_id2_len); | |
661 | skip = buffer_len(&b); | |
662 | } | |
663 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
664 | buffer_put_cstring(&b, authctxt->server_user); | |
665 | buffer_put_cstring(&b, | |
666 | datafellows & SSH_BUG_PUBKEYAUTH ? | |
667 | "ssh-userauth" : | |
668 | authctxt->service); | |
669 | buffer_put_cstring(&b, authctxt->method->name); | |
670 | buffer_put_char(&b, have_sig); | |
671 | buffer_put_cstring(&b, key_ssh_name(k)); | |
672 | buffer_put_string(&b, blob, bloblen); | |
673 | ||
674 | /* generate signature */ | |
675 | ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); | |
676 | if (ret == -1) { | |
677 | xfree(blob); | |
678 | buffer_free(&b); | |
679 | return 0; | |
680 | } | |
681 | #ifdef DEBUG_PK | |
682 | buffer_dump(&b); | |
683 | #endif | |
684 | if (datafellows & SSH_BUG_PUBKEYAUTH) { | |
685 | buffer_clear(&b); | |
686 | buffer_append(&b, session_id2, session_id2_len); | |
687 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
688 | buffer_put_cstring(&b, authctxt->server_user); | |
689 | buffer_put_cstring(&b, authctxt->service); | |
690 | buffer_put_cstring(&b, authctxt->method->name); | |
691 | buffer_put_char(&b, have_sig); | |
692 | buffer_put_cstring(&b, key_ssh_name(k)); | |
693 | buffer_put_string(&b, blob, bloblen); | |
694 | } | |
695 | xfree(blob); | |
696 | /* append signature */ | |
697 | buffer_put_string(&b, signature, slen); | |
698 | xfree(signature); | |
699 | ||
700 | /* skip session id and packet type */ | |
701 | if (buffer_len(&b) < skip + 1) | |
702 | fatal("userauth_pubkey: internal error"); | |
703 | buffer_consume(&b, skip + 1); | |
704 | ||
705 | /* put remaining data from buffer into packet */ | |
706 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
707 | packet_put_raw(buffer_ptr(&b), buffer_len(&b)); | |
708 | buffer_free(&b); | |
709 | ||
710 | /* send */ | |
711 | packet_send(); | |
712 | packet_write_wait(); | |
713 | ||
714 | return 1; | |
715 | } | |
716 | ||
717 | /* sign callback */ | |
718 | int key_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp, | |
719 | unsigned char *data, int datalen) | |
720 | { | |
721 | return key_sign(key, sigp, lenp, data, datalen); | |
722 | } | |
723 | ||
724 | int | |
725 | userauth_pubkey_identity(Authctxt *authctxt, char *filename) | |
726 | { | |
727 | Key *k; | |
728 | int i, ret, try_next; | |
729 | struct stat st; | |
730 | ||
731 | if (stat(filename, &st) != 0) { | |
732 | debug("key does not exist: %s", filename); | |
733 | return 0; | |
734 | } | |
735 | debug("try pubkey: %s", filename); | |
736 | ||
737 | k = key_new(KEY_UNSPEC); | |
738 | if (!load_private_key(filename, "", k, NULL)) { | |
739 | int success = 0; | |
740 | char *passphrase; | |
741 | char prompt[300]; | |
742 | snprintf(prompt, sizeof prompt, | |
743 | "Enter passphrase for key '%.100s': ", filename); | |
744 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
745 | passphrase = read_passphrase(prompt, 0); | |
746 | if (strcmp(passphrase, "") != 0) { | |
747 | success = load_private_key(filename, passphrase, k, NULL); | |
748 | try_next = 0; | |
749 | } else { | |
750 | debug2("no passphrase given, try next key"); | |
751 | try_next = 1; | |
752 | } | |
753 | memset(passphrase, 0, strlen(passphrase)); | |
754 | xfree(passphrase); | |
755 | if (success || try_next) | |
756 | break; | |
757 | debug2("bad passphrase given, try again..."); | |
758 | } | |
759 | if (!success) { | |
760 | key_free(k); | |
761 | return 0; | |
762 | } | |
763 | } | |
764 | ret = sign_and_send_pubkey(authctxt, k, key_sign_cb); | |
765 | key_free(k); | |
766 | return ret; | |
767 | } | |
768 | ||
769 | /* sign callback */ | |
770 | int agent_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp, | |
771 | unsigned char *data, int datalen) | |
772 | { | |
773 | return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); | |
774 | } | |
775 | ||
776 | int | |
777 | userauth_pubkey_agent(Authctxt *authctxt) | |
778 | { | |
779 | static int called = 0; | |
780 | int ret = 0; | |
781 | char *comment; | |
782 | Key *k; | |
783 | ||
784 | if (called == 0) { | |
785 | if (ssh_get_num_identities(authctxt->agent, 2) == 0) | |
786 | debug2("userauth_pubkey_agent: no keys at all"); | |
787 | called = 1; | |
788 | } | |
789 | k = ssh_get_next_identity(authctxt->agent, &comment, 2); | |
790 | if (k == NULL) { | |
791 | debug2("userauth_pubkey_agent: no more keys"); | |
792 | } else { | |
793 | debug("userauth_pubkey_agent: trying agent key %s", comment); | |
794 | xfree(comment); | |
795 | ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb); | |
796 | key_free(k); | |
797 | } | |
798 | if (ret == 0) | |
799 | debug2("userauth_pubkey_agent: no message sent"); | |
800 | return ret; | |
801 | } | |
802 | ||
803 | int | |
804 | userauth_pubkey(Authctxt *authctxt) | |
805 | { | |
806 | static int idx = 0; | |
807 | int sent = 0; | |
808 | ||
809 | if (authctxt->agent != NULL) { | |
810 | do { | |
811 | sent = userauth_pubkey_agent(authctxt); | |
812 | } while(!sent && authctxt->agent->howmany > 0); | |
813 | } | |
814 | while (!sent && idx < options.num_identity_files) { | |
815 | if (options.identity_files_type[idx] != KEY_RSA1) | |
816 | sent = userauth_pubkey_identity(authctxt, | |
817 | options.identity_files[idx]); | |
818 | idx++; | |
819 | } | |
820 | return sent; | |
821 | } | |
822 | ||
823 | /* | |
824 | * Send userauth request message specifying keyboard-interactive method. | |
825 | */ | |
826 | int | |
827 | userauth_kbdint(Authctxt *authctxt) | |
828 | { | |
829 | static int attempt = 0; | |
830 | ||
831 | if (attempt++ >= options.number_of_password_prompts) | |
832 | return 0; | |
833 | ||
834 | debug2("userauth_kbdint"); | |
835 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
836 | packet_put_cstring(authctxt->server_user); | |
837 | packet_put_cstring(authctxt->service); | |
838 | packet_put_cstring(authctxt->method->name); | |
839 | packet_put_cstring(""); /* lang */ | |
840 | packet_put_cstring(options.kbd_interactive_devices ? | |
841 | options.kbd_interactive_devices : ""); | |
842 | packet_send(); | |
843 | packet_write_wait(); | |
844 | ||
845 | dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); | |
846 | return 1; | |
847 | } | |
848 | ||
849 | /* | |
850 | * parse SSH2_MSG_USERAUTH_INFO_REQUEST, prompt user and send | |
851 | * SSH2_MSG_USERAUTH_INFO_RESPONSE | |
852 | */ | |
853 | void | |
854 | input_userauth_info_req(int type, int plen, void *ctxt) | |
855 | { | |
856 | Authctxt *authctxt = ctxt; | |
857 | char *name = NULL; | |
858 | char *inst = NULL; | |
859 | char *lang = NULL; | |
860 | char *prompt = NULL; | |
861 | char *response = NULL; | |
862 | unsigned int num_prompts, i; | |
863 | int echo = 0; | |
864 | ||
865 | debug2("input_userauth_info_req"); | |
866 | ||
867 | if (authctxt == NULL) | |
868 | fatal("input_userauth_info_req: no authentication context"); | |
869 | ||
870 | name = packet_get_string(NULL); | |
871 | inst = packet_get_string(NULL); | |
872 | lang = packet_get_string(NULL); | |
873 | ||
874 | if (strlen(name) > 0) | |
875 | cli_mesg(name); | |
876 | xfree(name); | |
877 | ||
878 | if (strlen(inst) > 0) | |
879 | cli_mesg(inst); | |
880 | xfree(inst); | |
881 | xfree(lang); /* unused */ | |
882 | ||
883 | num_prompts = packet_get_int(); | |
884 | /* | |
885 | * Begin to build info response packet based on prompts requested. | |
886 | * We commit to providing the correct number of responses, so if | |
887 | * further on we run into a problem that prevents this, we have to | |
888 | * be sure and clean this up and send a correct error response. | |
889 | */ | |
890 | packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); | |
891 | packet_put_int(num_prompts); | |
892 | ||
893 | for (i = 0; i < num_prompts; i++) { | |
894 | prompt = packet_get_string(NULL); | |
895 | echo = packet_get_char(); | |
896 | ||
897 | response = cli_prompt(prompt, echo); | |
898 | ||
899 | packet_put_cstring(response); | |
900 | memset(response, 0, strlen(response)); | |
901 | xfree(response); | |
902 | xfree(prompt); | |
903 | } | |
904 | packet_done(); /* done with parsing incoming message. */ | |
905 | ||
906 | packet_send(); | |
907 | packet_write_wait(); | |
908 | } | |
909 | ||
910 | /* find auth method */ | |
911 | ||
912 | #define DELIM "," | |
913 | ||
914 | static char *def_authlist = "publickey,password"; | |
915 | static char *authlist_current = NULL; /* clean copy used for comparison */ | |
916 | static char *authname_current = NULL; /* last used auth method */ | |
917 | static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */ | |
918 | static char *authlist_state = NULL; /* state variable for strtok_r() */ | |
919 | ||
920 | /* | |
921 | * Before starting to use a new authentication method list sent by the | |
922 | * server, reset internal variables. This should also be called when | |
923 | * finished processing server list to free resources. | |
924 | */ | |
925 | void | |
926 | authmethod_clear() | |
927 | { | |
928 | if (authlist_current != NULL) { | |
929 | xfree(authlist_current); | |
930 | authlist_current = NULL; | |
931 | } | |
932 | if (authlist_working != NULL) { | |
933 | xfree(authlist_working); | |
934 | authlist_working = NULL; | |
935 | } | |
936 | if (authname_current != NULL) { | |
937 | xfree(authname_current); | |
938 | authlist_state = NULL; | |
939 | } | |
940 | if (authlist_state != NULL) | |
941 | authlist_state = NULL; | |
942 | return; | |
943 | } | |
944 | ||
945 | /* | |
946 | * given auth method name, if configurable options permit this method fill | |
947 | * in auth_ident field and return true, otherwise return false. | |
948 | */ | |
949 | int | |
950 | authmethod_is_enabled(Authmethod *method) | |
951 | { | |
952 | if (method == NULL) | |
953 | return 0; | |
954 | /* return false if options indicate this method is disabled */ | |
955 | if (method->enabled == NULL || *method->enabled == 0) | |
956 | return 0; | |
957 | /* return false if batch mode is enabled but method needs interactive mode */ | |
958 | if (method->batch_flag != NULL && *method->batch_flag != 0) | |
959 | return 0; | |
960 | return 1; | |
961 | } | |
962 | ||
963 | Authmethod * | |
964 | authmethod_lookup(const char *name) | |
965 | { | |
966 | Authmethod *method = NULL; | |
967 | if (name != NULL) | |
968 | for (method = authmethods; method->name != NULL; method++) | |
969 | if (strcmp(name, method->name) == 0) | |
970 | return method; | |
971 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
972 | return NULL; | |
973 | } | |
974 | ||
975 | /* | |
976 | * Given the authentication method list sent by the server, return the | |
977 | * next method we should try. If the server initially sends a nil list, | |
978 | * use a built-in default list. If the server sends a nil list after | |
979 | * previously sending a valid list, continue using the list originally | |
980 | * sent. | |
981 | */ | |
982 | ||
983 | Authmethod * | |
984 | authmethod_get(char *authlist) | |
985 | { | |
986 | char *name = NULL, *authname_old; | |
987 | Authmethod *method = NULL; | |
988 | ||
989 | /* Use a suitable default if we're passed a nil list. */ | |
990 | if (authlist == NULL || strlen(authlist) == 0) | |
991 | authlist = def_authlist; | |
992 | ||
993 | if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) { | |
994 | /* start over if passed a different list */ | |
995 | debug3("start over, passed a different list"); | |
996 | authmethod_clear(); | |
997 | authlist_current = xstrdup(authlist); | |
998 | authlist_working = xstrdup(authlist); | |
999 | name = strtok_r(authlist_working, DELIM, &authlist_state); | |
1000 | } else { | |
1001 | /* | |
1002 | * try to use previously used authentication method | |
1003 | * or continue to use previously passed list | |
1004 | */ | |
1005 | name = (authname_current != NULL) ? | |
1006 | authname_current : strtok_r(NULL, DELIM, &authlist_state); | |
1007 | } | |
1008 | ||
1009 | while (name != NULL) { | |
1010 | debug3("authmethod_lookup %s", name); | |
1011 | method = authmethod_lookup(name); | |
1012 | if (method != NULL && authmethod_is_enabled(method)) { | |
1013 | debug3("authmethod_is_enabled %s", name); | |
1014 | break; | |
1015 | } | |
1016 | name = strtok_r(NULL, DELIM, &authlist_state); | |
1017 | method = NULL; | |
1018 | } | |
1019 | ||
1020 | authname_old = authname_current; | |
1021 | if (method != NULL) { | |
1022 | debug("next auth method to try is %s", name); | |
1023 | authname_current = xstrdup(name); | |
1024 | } else { | |
1025 | debug("no more auth methods to try"); | |
1026 | authname_current = NULL; | |
1027 | } | |
1028 | ||
1029 | if (authname_old != NULL) | |
1030 | xfree(authname_old); | |
1031 | ||
1032 | return (method); | |
1033 | } |