]>
Commit | Line | Data |
---|---|---|
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 1.50 2001/03/05 17:17:21 markus Exp $"); | |
27 | ||
28 | #include <openssl/bn.h> | |
29 | #include <openssl/md5.h> | |
30 | #include <openssl/dh.h> | |
31 | #include <openssl/hmac.h> | |
32 | ||
33 | #include "ssh.h" | |
34 | #include "ssh2.h" | |
35 | #include "xmalloc.h" | |
36 | #include "rsa.h" | |
37 | #include "buffer.h" | |
38 | #include "packet.h" | |
39 | #include "uidswap.h" | |
40 | #include "compat.h" | |
41 | #include "bufaux.h" | |
42 | #include "cipher.h" | |
43 | #include "kex.h" | |
44 | #include "myproposal.h" | |
45 | #include "key.h" | |
46 | #include "sshconnect.h" | |
47 | #include "authfile.h" | |
48 | #include "cli.h" | |
49 | #include "dispatch.h" | |
50 | #include "authfd.h" | |
51 | #include "log.h" | |
52 | #include "readconf.h" | |
53 | #include "readpass.h" | |
54 | ||
55 | void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); | |
56 | void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); | |
57 | ||
58 | /* import */ | |
59 | extern char *client_version_string; | |
60 | extern char *server_version_string; | |
61 | extern Options options; | |
62 | ||
63 | /* | |
64 | * SSH2 key exchange | |
65 | */ | |
66 | ||
67 | u_char *session_id2 = NULL; | |
68 | int session_id2_len = 0; | |
69 | ||
70 | void | |
71 | ssh_kex2(char *host, struct sockaddr *hostaddr) | |
72 | { | |
73 | int i, plen; | |
74 | Kex *kex; | |
75 | Buffer *client_kexinit, *server_kexinit; | |
76 | char *sprop[PROPOSAL_MAX]; | |
77 | ||
78 | if (options.ciphers == (char *)-1) { | |
79 | log("No valid ciphers for protocol version 2 given, using defaults."); | |
80 | options.ciphers = NULL; | |
81 | } | |
82 | if (options.ciphers != NULL) { | |
83 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
84 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
85 | } | |
86 | if (options.compression) { | |
87 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
88 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; | |
89 | } else { | |
90 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
91 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
92 | } | |
93 | if (options.macs != NULL) { | |
94 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
95 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
96 | } | |
97 | ||
98 | /* buffers with raw kexinit messages */ | |
99 | server_kexinit = xmalloc(sizeof(*server_kexinit)); | |
100 | buffer_init(server_kexinit); | |
101 | client_kexinit = kex_init(myproposal); | |
102 | ||
103 | /* algorithm negotiation */ | |
104 | kex_exchange_kexinit(client_kexinit, server_kexinit, sprop); | |
105 | kex = kex_choose_conf(myproposal, sprop, 0); | |
106 | for (i = 0; i < PROPOSAL_MAX; i++) | |
107 | xfree(sprop[i]); | |
108 | ||
109 | /* server authentication and session key agreement */ | |
110 | switch(kex->kex_type) { | |
111 | case DH_GRP1_SHA1: | |
112 | ssh_dh1_client(kex, host, hostaddr, | |
113 | client_kexinit, server_kexinit); | |
114 | break; | |
115 | case DH_GEX_SHA1: | |
116 | ssh_dhgex_client(kex, host, hostaddr, client_kexinit, | |
117 | server_kexinit); | |
118 | break; | |
119 | default: | |
120 | fatal("Unsupported key exchange %d", kex->kex_type); | |
121 | } | |
122 | ||
123 | buffer_free(client_kexinit); | |
124 | buffer_free(server_kexinit); | |
125 | xfree(client_kexinit); | |
126 | xfree(server_kexinit); | |
127 | ||
128 | debug("Wait SSH2_MSG_NEWKEYS."); | |
129 | packet_read_expect(&plen, SSH2_MSG_NEWKEYS); | |
130 | packet_done(); | |
131 | debug("GOT SSH2_MSG_NEWKEYS."); | |
132 | ||
133 | debug("send SSH2_MSG_NEWKEYS."); | |
134 | packet_start(SSH2_MSG_NEWKEYS); | |
135 | packet_send(); | |
136 | packet_write_wait(); | |
137 | debug("done: send SSH2_MSG_NEWKEYS."); | |
138 | ||
139 | #ifdef DEBUG_KEXDH | |
140 | /* send 1st encrypted/maced/compressed message */ | |
141 | packet_start(SSH2_MSG_IGNORE); | |
142 | packet_put_cstring("markus"); | |
143 | packet_send(); | |
144 | packet_write_wait(); | |
145 | #endif | |
146 | debug("done: KEX2."); | |
147 | } | |
148 | ||
149 | /* diffie-hellman-group1-sha1 */ | |
150 | ||
151 | void | |
152 | ssh_dh1_client(Kex *kex, char *host, struct sockaddr *hostaddr, | |
153 | Buffer *client_kexinit, Buffer *server_kexinit) | |
154 | { | |
155 | #ifdef DEBUG_KEXDH | |
156 | int i; | |
157 | #endif | |
158 | int plen, dlen; | |
159 | u_int klen, kout; | |
160 | char *signature = NULL; | |
161 | u_int slen; | |
162 | char *server_host_key_blob = NULL; | |
163 | Key *server_host_key; | |
164 | u_int sbloblen; | |
165 | DH *dh; | |
166 | BIGNUM *dh_server_pub = 0; | |
167 | BIGNUM *shared_secret = 0; | |
168 | u_char *kbuf; | |
169 | u_char *hash; | |
170 | ||
171 | debug("Sending SSH2_MSG_KEXDH_INIT."); | |
172 | /* generate and send 'e', client DH public key */ | |
173 | dh = dh_new_group1(); | |
174 | dh_gen_key(dh, kex->we_need * 8); | |
175 | packet_start(SSH2_MSG_KEXDH_INIT); | |
176 | packet_put_bignum2(dh->pub_key); | |
177 | packet_send(); | |
178 | packet_write_wait(); | |
179 | ||
180 | #ifdef DEBUG_KEXDH | |
181 | fprintf(stderr, "\np= "); | |
182 | BN_print_fp(stderr, dh->p); | |
183 | fprintf(stderr, "\ng= "); | |
184 | BN_print_fp(stderr, dh->g); | |
185 | fprintf(stderr, "\npub= "); | |
186 | BN_print_fp(stderr, dh->pub_key); | |
187 | fprintf(stderr, "\n"); | |
188 | DHparams_print_fp(stderr, dh); | |
189 | #endif | |
190 | ||
191 | debug("Wait SSH2_MSG_KEXDH_REPLY."); | |
192 | ||
193 | packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY); | |
194 | ||
195 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
196 | ||
197 | /* key, cert */ | |
198 | server_host_key_blob = packet_get_string(&sbloblen); | |
199 | server_host_key = key_from_blob(server_host_key_blob, sbloblen); | |
200 | if (server_host_key == NULL) | |
201 | fatal("cannot decode server_host_key_blob"); | |
202 | ||
203 | check_host_key(host, hostaddr, server_host_key, | |
204 | options.user_hostfile2, options.system_hostfile2); | |
205 | ||
206 | /* DH paramter f, server public DH key */ | |
207 | dh_server_pub = BN_new(); | |
208 | if (dh_server_pub == NULL) | |
209 | fatal("dh_server_pub == NULL"); | |
210 | packet_get_bignum2(dh_server_pub, &dlen); | |
211 | ||
212 | #ifdef DEBUG_KEXDH | |
213 | fprintf(stderr, "\ndh_server_pub= "); | |
214 | BN_print_fp(stderr, dh_server_pub); | |
215 | fprintf(stderr, "\n"); | |
216 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
217 | #endif | |
218 | ||
219 | /* signed H */ | |
220 | signature = packet_get_string(&slen); | |
221 | packet_done(); | |
222 | ||
223 | if (!dh_pub_is_valid(dh, dh_server_pub)) | |
224 | packet_disconnect("bad server public DH value"); | |
225 | ||
226 | klen = DH_size(dh); | |
227 | kbuf = xmalloc(klen); | |
228 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
229 | #ifdef DEBUG_KEXDH | |
230 | debug("shared secret: len %d/%d", klen, kout); | |
231 | fprintf(stderr, "shared secret == "); | |
232 | for (i = 0; i< kout; i++) | |
233 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
234 | fprintf(stderr, "\n"); | |
235 | #endif | |
236 | shared_secret = BN_new(); | |
237 | ||
238 | BN_bin2bn(kbuf, kout, shared_secret); | |
239 | memset(kbuf, 0, klen); | |
240 | xfree(kbuf); | |
241 | ||
242 | /* calc and verify H */ | |
243 | hash = kex_hash( | |
244 | client_version_string, | |
245 | server_version_string, | |
246 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
247 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
248 | server_host_key_blob, sbloblen, | |
249 | dh->pub_key, | |
250 | dh_server_pub, | |
251 | shared_secret | |
252 | ); | |
253 | xfree(server_host_key_blob); | |
254 | DH_free(dh); | |
255 | BN_free(dh_server_pub); | |
256 | #ifdef DEBUG_KEXDH | |
257 | fprintf(stderr, "hash == "); | |
258 | for (i = 0; i< 20; i++) | |
259 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
260 | fprintf(stderr, "\n"); | |
261 | #endif | |
262 | if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1) | |
263 | fatal("key_verify failed for server_host_key"); | |
264 | key_free(server_host_key); | |
265 | xfree(signature); | |
266 | ||
267 | kex_derive_keys(kex, hash, shared_secret); | |
268 | BN_clear_free(shared_secret); | |
269 | packet_set_kex(kex); | |
270 | ||
271 | /* save session id */ | |
272 | session_id2_len = 20; | |
273 | session_id2 = xmalloc(session_id2_len); | |
274 | memcpy(session_id2, hash, session_id2_len); | |
275 | } | |
276 | ||
277 | /* diffie-hellman-group-exchange-sha1 */ | |
278 | ||
279 | /* | |
280 | * Estimates the group order for a Diffie-Hellman group that has an | |
281 | * attack complexity approximately the same as O(2**bits). Estimate | |
282 | * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))) | |
283 | */ | |
284 | ||
285 | int | |
286 | dh_estimate(int bits) | |
287 | { | |
288 | ||
289 | if (bits < 64) | |
290 | return (512); /* O(2**63) */ | |
291 | if (bits < 128) | |
292 | return (1024); /* O(2**86) */ | |
293 | if (bits < 192) | |
294 | return (2048); /* O(2**116) */ | |
295 | return (4096); /* O(2**156) */ | |
296 | } | |
297 | ||
298 | void | |
299 | ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr, | |
300 | Buffer *client_kexinit, Buffer *server_kexinit) | |
301 | { | |
302 | #ifdef DEBUG_KEXDH | |
303 | int i; | |
304 | #endif | |
305 | int plen, dlen; | |
306 | u_int klen, kout; | |
307 | char *signature = NULL; | |
308 | u_int slen, nbits; | |
309 | char *server_host_key_blob = NULL; | |
310 | Key *server_host_key; | |
311 | u_int sbloblen; | |
312 | DH *dh; | |
313 | BIGNUM *dh_server_pub = 0; | |
314 | BIGNUM *shared_secret = 0; | |
315 | BIGNUM *p = 0, *g = 0; | |
316 | u_char *kbuf; | |
317 | u_char *hash; | |
318 | ||
319 | nbits = dh_estimate(kex->we_need * 8); | |
320 | ||
321 | debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST."); | |
322 | packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST); | |
323 | packet_put_int(nbits); | |
324 | packet_send(); | |
325 | packet_write_wait(); | |
326 | ||
327 | #ifdef DEBUG_KEXDH | |
328 | fprintf(stderr, "\nnbits = %d", nbits); | |
329 | #endif | |
330 | ||
331 | debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP."); | |
332 | ||
333 | packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP); | |
334 | ||
335 | debug("Got SSH2_MSG_KEX_DH_GEX_GROUP."); | |
336 | ||
337 | if ((p = BN_new()) == NULL) | |
338 | fatal("BN_new"); | |
339 | packet_get_bignum2(p, &dlen); | |
340 | if ((g = BN_new()) == NULL) | |
341 | fatal("BN_new"); | |
342 | packet_get_bignum2(g, &dlen); | |
343 | dh = dh_new_group(g, p); | |
344 | ||
345 | dh_gen_key(dh, kex->we_need * 8); | |
346 | ||
347 | #ifdef DEBUG_KEXDH | |
348 | fprintf(stderr, "\np= "); | |
349 | BN_print_fp(stderr, dh->p); | |
350 | fprintf(stderr, "\ng= "); | |
351 | BN_print_fp(stderr, dh->g); | |
352 | fprintf(stderr, "\npub= "); | |
353 | BN_print_fp(stderr, dh->pub_key); | |
354 | fprintf(stderr, "\n"); | |
355 | DHparams_print_fp(stderr, dh); | |
356 | #endif | |
357 | ||
358 | debug("Sending SSH2_MSG_KEX_DH_GEX_INIT."); | |
359 | /* generate and send 'e', client DH public key */ | |
360 | packet_start(SSH2_MSG_KEX_DH_GEX_INIT); | |
361 | packet_put_bignum2(dh->pub_key); | |
362 | packet_send(); | |
363 | packet_write_wait(); | |
364 | ||
365 | debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY."); | |
366 | ||
367 | packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY); | |
368 | ||
369 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
370 | ||
371 | /* key, cert */ | |
372 | server_host_key_blob = packet_get_string(&sbloblen); | |
373 | server_host_key = key_from_blob(server_host_key_blob, sbloblen); | |
374 | if (server_host_key == NULL) | |
375 | fatal("cannot decode server_host_key_blob"); | |
376 | ||
377 | check_host_key(host, hostaddr, server_host_key, | |
378 | options.user_hostfile2, options.system_hostfile2); | |
379 | ||
380 | /* DH paramter f, server public DH key */ | |
381 | dh_server_pub = BN_new(); | |
382 | if (dh_server_pub == NULL) | |
383 | fatal("dh_server_pub == NULL"); | |
384 | packet_get_bignum2(dh_server_pub, &dlen); | |
385 | ||
386 | #ifdef DEBUG_KEXDH | |
387 | fprintf(stderr, "\ndh_server_pub= "); | |
388 | BN_print_fp(stderr, dh_server_pub); | |
389 | fprintf(stderr, "\n"); | |
390 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
391 | #endif | |
392 | ||
393 | /* signed H */ | |
394 | signature = packet_get_string(&slen); | |
395 | packet_done(); | |
396 | ||
397 | if (!dh_pub_is_valid(dh, dh_server_pub)) | |
398 | packet_disconnect("bad server public DH value"); | |
399 | ||
400 | klen = DH_size(dh); | |
401 | kbuf = xmalloc(klen); | |
402 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
403 | #ifdef DEBUG_KEXDH | |
404 | debug("shared secret: len %d/%d", klen, kout); | |
405 | fprintf(stderr, "shared secret == "); | |
406 | for (i = 0; i< kout; i++) | |
407 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
408 | fprintf(stderr, "\n"); | |
409 | #endif | |
410 | shared_secret = BN_new(); | |
411 | ||
412 | BN_bin2bn(kbuf, kout, shared_secret); | |
413 | memset(kbuf, 0, klen); | |
414 | xfree(kbuf); | |
415 | ||
416 | /* calc and verify H */ | |
417 | hash = kex_hash_gex( | |
418 | client_version_string, | |
419 | server_version_string, | |
420 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
421 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
422 | server_host_key_blob, sbloblen, | |
423 | nbits, dh->p, dh->g, | |
424 | dh->pub_key, | |
425 | dh_server_pub, | |
426 | shared_secret | |
427 | ); | |
428 | xfree(server_host_key_blob); | |
429 | DH_free(dh); | |
430 | BN_free(dh_server_pub); | |
431 | #ifdef DEBUG_KEXDH | |
432 | fprintf(stderr, "hash == "); | |
433 | for (i = 0; i< 20; i++) | |
434 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
435 | fprintf(stderr, "\n"); | |
436 | #endif | |
437 | if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1) | |
438 | fatal("key_verify failed for server_host_key"); | |
439 | key_free(server_host_key); | |
440 | xfree(signature); | |
441 | ||
442 | kex_derive_keys(kex, hash, shared_secret); | |
443 | BN_clear_free(shared_secret); | |
444 | packet_set_kex(kex); | |
445 | ||
446 | /* save session id */ | |
447 | session_id2_len = 20; | |
448 | session_id2 = xmalloc(session_id2_len); | |
449 | memcpy(session_id2, hash, session_id2_len); | |
450 | } | |
451 | ||
452 | /* | |
453 | * Authenticate user | |
454 | */ | |
455 | ||
456 | typedef struct Authctxt Authctxt; | |
457 | typedef struct Authmethod Authmethod; | |
458 | ||
459 | typedef int sign_cb_fn( | |
460 | Authctxt *authctxt, Key *key, | |
461 | u_char **sigp, int *lenp, u_char *data, int datalen); | |
462 | ||
463 | struct Authctxt { | |
464 | const char *server_user; | |
465 | const char *host; | |
466 | const char *service; | |
467 | AuthenticationConnection *agent; | |
468 | Authmethod *method; | |
469 | int success; | |
470 | }; | |
471 | struct Authmethod { | |
472 | char *name; /* string to compare against server's list */ | |
473 | int (*userauth)(Authctxt *authctxt); | |
474 | int *enabled; /* flag in option struct that enables method */ | |
475 | int *batch_flag; /* flag in option struct that disables method */ | |
476 | }; | |
477 | ||
478 | void input_userauth_success(int type, int plen, void *ctxt); | |
479 | void input_userauth_failure(int type, int plen, void *ctxt); | |
480 | void input_userauth_banner(int type, int plen, void *ctxt); | |
481 | void input_userauth_error(int type, int plen, void *ctxt); | |
482 | void input_userauth_info_req(int type, int plen, void *ctxt); | |
483 | ||
484 | int userauth_none(Authctxt *authctxt); | |
485 | int userauth_pubkey(Authctxt *authctxt); | |
486 | int userauth_passwd(Authctxt *authctxt); | |
487 | int userauth_kbdint(Authctxt *authctxt); | |
488 | ||
489 | void authmethod_clear(void); | |
490 | Authmethod *authmethod_get(char *authlist); | |
491 | Authmethod *authmethod_lookup(const char *name); | |
492 | ||
493 | Authmethod authmethods[] = { | |
494 | {"publickey", | |
495 | userauth_pubkey, | |
496 | &options.pubkey_authentication, | |
497 | NULL}, | |
498 | {"password", | |
499 | userauth_passwd, | |
500 | &options.password_authentication, | |
501 | &options.batch_mode}, | |
502 | {"keyboard-interactive", | |
503 | userauth_kbdint, | |
504 | &options.kbd_interactive_authentication, | |
505 | &options.batch_mode}, | |
506 | {"none", | |
507 | userauth_none, | |
508 | NULL, | |
509 | NULL}, | |
510 | {NULL, NULL, NULL, NULL} | |
511 | }; | |
512 | ||
513 | void | |
514 | ssh_userauth2(const char *server_user, char *host) | |
515 | { | |
516 | Authctxt authctxt; | |
517 | int type; | |
518 | int plen; | |
519 | ||
520 | if (options.challenge_reponse_authentication) | |
521 | options.kbd_interactive_authentication = 1; | |
522 | ||
523 | debug("send SSH2_MSG_SERVICE_REQUEST"); | |
524 | packet_start(SSH2_MSG_SERVICE_REQUEST); | |
525 | packet_put_cstring("ssh-userauth"); | |
526 | packet_send(); | |
527 | packet_write_wait(); | |
528 | type = packet_read(&plen); | |
529 | if (type != SSH2_MSG_SERVICE_ACCEPT) { | |
530 | fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); | |
531 | } | |
532 | if (packet_remaining() > 0) { | |
533 | char *reply = packet_get_string(&plen); | |
534 | debug("service_accept: %s", reply); | |
535 | xfree(reply); | |
536 | } else { | |
537 | debug("buggy server: service_accept w/o service"); | |
538 | } | |
539 | packet_done(); | |
540 | debug("got SSH2_MSG_SERVICE_ACCEPT"); | |
541 | ||
542 | /* setup authentication context */ | |
543 | authctxt.agent = ssh_get_authentication_connection(); | |
544 | authctxt.server_user = server_user; | |
545 | authctxt.host = host; | |
546 | authctxt.service = "ssh-connection"; /* service name */ | |
547 | authctxt.success = 0; | |
548 | authctxt.method = authmethod_lookup("none"); | |
549 | if (authctxt.method == NULL) | |
550 | fatal("ssh_userauth2: internal error: cannot send userauth none request"); | |
551 | authmethod_clear(); | |
552 | ||
553 | /* initial userauth request */ | |
554 | userauth_none(&authctxt); | |
555 | ||
556 | dispatch_init(&input_userauth_error); | |
557 | dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); | |
558 | dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); | |
559 | dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); | |
560 | dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ | |
561 | ||
562 | if (authctxt.agent != NULL) | |
563 | ssh_close_authentication_connection(authctxt.agent); | |
564 | ||
565 | debug("ssh-userauth2 successful: method %s", authctxt.method->name); | |
566 | } | |
567 | void | |
568 | input_userauth_error(int type, int plen, void *ctxt) | |
569 | { | |
570 | fatal("input_userauth_error: bad message during authentication: " | |
571 | "type %d", type); | |
572 | } | |
573 | void | |
574 | input_userauth_banner(int type, int plen, void *ctxt) | |
575 | { | |
576 | char *msg, *lang; | |
577 | debug3("input_userauth_banner"); | |
578 | msg = packet_get_string(NULL); | |
579 | lang = packet_get_string(NULL); | |
580 | fprintf(stderr, "%s", msg); | |
581 | xfree(msg); | |
582 | xfree(lang); | |
583 | } | |
584 | void | |
585 | input_userauth_success(int type, int plen, void *ctxt) | |
586 | { | |
587 | Authctxt *authctxt = ctxt; | |
588 | if (authctxt == NULL) | |
589 | fatal("input_userauth_success: no authentication context"); | |
590 | authctxt->success = 1; /* break out */ | |
591 | } | |
592 | void | |
593 | input_userauth_failure(int type, int plen, void *ctxt) | |
594 | { | |
595 | Authmethod *method = NULL; | |
596 | Authctxt *authctxt = ctxt; | |
597 | char *authlist = NULL; | |
598 | int partial; | |
599 | ||
600 | if (authctxt == NULL) | |
601 | fatal("input_userauth_failure: no authentication context"); | |
602 | ||
603 | authlist = packet_get_string(NULL); | |
604 | partial = packet_get_char(); | |
605 | packet_done(); | |
606 | ||
607 | if (partial != 0) | |
608 | log("Authenticated with partial success."); | |
609 | debug("authentications that can continue: %s", authlist); | |
610 | ||
611 | for (;;) { | |
612 | method = authmethod_get(authlist); | |
613 | if (method == NULL) | |
614 | fatal("Permission denied (%s).", authlist); | |
615 | authctxt->method = method; | |
616 | if (method->userauth(authctxt) != 0) { | |
617 | debug2("we sent a %s packet, wait for reply", method->name); | |
618 | break; | |
619 | } else { | |
620 | debug2("we did not send a packet, disable method"); | |
621 | method->enabled = NULL; | |
622 | } | |
623 | } | |
624 | xfree(authlist); | |
625 | } | |
626 | ||
627 | int | |
628 | userauth_none(Authctxt *authctxt) | |
629 | { | |
630 | /* initial userauth request */ | |
631 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
632 | packet_put_cstring(authctxt->server_user); | |
633 | packet_put_cstring(authctxt->service); | |
634 | packet_put_cstring(authctxt->method->name); | |
635 | packet_send(); | |
636 | packet_write_wait(); | |
637 | return 1; | |
638 | } | |
639 | ||
640 | int | |
641 | userauth_passwd(Authctxt *authctxt) | |
642 | { | |
643 | static int attempt = 0; | |
644 | char prompt[80]; | |
645 | char *password; | |
646 | ||
647 | if (attempt++ >= options.number_of_password_prompts) | |
648 | return 0; | |
649 | ||
650 | if(attempt != 1) | |
651 | error("Permission denied, please try again."); | |
652 | ||
653 | snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", | |
654 | authctxt->server_user, authctxt->host); | |
655 | password = read_passphrase(prompt, 0); | |
656 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
657 | packet_put_cstring(authctxt->server_user); | |
658 | packet_put_cstring(authctxt->service); | |
659 | packet_put_cstring(authctxt->method->name); | |
660 | packet_put_char(0); | |
661 | packet_put_cstring(password); | |
662 | memset(password, 0, strlen(password)); | |
663 | xfree(password); | |
664 | packet_inject_ignore(64); | |
665 | packet_send(); | |
666 | packet_write_wait(); | |
667 | return 1; | |
668 | } | |
669 | ||
670 | int | |
671 | sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) | |
672 | { | |
673 | Buffer b; | |
674 | u_char *blob, *signature; | |
675 | int bloblen, slen; | |
676 | int skip = 0; | |
677 | int ret = -1; | |
678 | int have_sig = 1; | |
679 | ||
680 | debug3("sign_and_send_pubkey"); | |
681 | if (key_to_blob(k, &blob, &bloblen) == 0) { | |
682 | /* we cannot handle this key */ | |
683 | debug3("sign_and_send_pubkey: cannot handle key"); | |
684 | return 0; | |
685 | } | |
686 | /* data to be signed */ | |
687 | buffer_init(&b); | |
688 | if (datafellows & SSH_OLD_SESSIONID) { | |
689 | buffer_append(&b, session_id2, session_id2_len); | |
690 | skip = session_id2_len; | |
691 | } else { | |
692 | buffer_put_string(&b, session_id2, session_id2_len); | |
693 | skip = buffer_len(&b); | |
694 | } | |
695 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
696 | buffer_put_cstring(&b, authctxt->server_user); | |
697 | buffer_put_cstring(&b, | |
698 | datafellows & SSH_BUG_PKSERVICE ? | |
699 | "ssh-userauth" : | |
700 | authctxt->service); | |
701 | if (datafellows & SSH_BUG_PKAUTH) { | |
702 | buffer_put_char(&b, have_sig); | |
703 | } else { | |
704 | buffer_put_cstring(&b, authctxt->method->name); | |
705 | buffer_put_char(&b, have_sig); | |
706 | buffer_put_cstring(&b, key_ssh_name(k)); | |
707 | } | |
708 | buffer_put_string(&b, blob, bloblen); | |
709 | ||
710 | /* generate signature */ | |
711 | ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); | |
712 | if (ret == -1) { | |
713 | xfree(blob); | |
714 | buffer_free(&b); | |
715 | return 0; | |
716 | } | |
717 | #ifdef DEBUG_PK | |
718 | buffer_dump(&b); | |
719 | #endif | |
720 | if (datafellows & SSH_BUG_PKSERVICE) { | |
721 | buffer_clear(&b); | |
722 | buffer_append(&b, session_id2, session_id2_len); | |
723 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
724 | buffer_put_cstring(&b, authctxt->server_user); | |
725 | buffer_put_cstring(&b, authctxt->service); | |
726 | buffer_put_cstring(&b, authctxt->method->name); | |
727 | buffer_put_char(&b, have_sig); | |
728 | if (!(datafellows & SSH_BUG_PKAUTH)) | |
729 | buffer_put_cstring(&b, key_ssh_name(k)); | |
730 | buffer_put_string(&b, blob, bloblen); | |
731 | } | |
732 | xfree(blob); | |
733 | /* append signature */ | |
734 | buffer_put_string(&b, signature, slen); | |
735 | xfree(signature); | |
736 | ||
737 | /* skip session id and packet type */ | |
738 | if (buffer_len(&b) < skip + 1) | |
739 | fatal("userauth_pubkey: internal error"); | |
740 | buffer_consume(&b, skip + 1); | |
741 | ||
742 | /* put remaining data from buffer into packet */ | |
743 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
744 | packet_put_raw(buffer_ptr(&b), buffer_len(&b)); | |
745 | buffer_free(&b); | |
746 | ||
747 | /* send */ | |
748 | packet_send(); | |
749 | packet_write_wait(); | |
750 | ||
751 | return 1; | |
752 | } | |
753 | ||
754 | /* sign callback */ | |
755 | int key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp, | |
756 | u_char *data, int datalen) | |
757 | { | |
758 | return key_sign(key, sigp, lenp, data, datalen); | |
759 | } | |
760 | ||
761 | int | |
762 | userauth_pubkey_identity(Authctxt *authctxt, char *filename) | |
763 | { | |
764 | Key *k; | |
765 | int i, ret, try_next, success = 0; | |
766 | struct stat st; | |
767 | char *passphrase; | |
768 | char prompt[300]; | |
769 | ||
770 | if (stat(filename, &st) != 0) { | |
771 | debug("key does not exist: %s", filename); | |
772 | return 0; | |
773 | } | |
774 | debug("try pubkey: %s", filename); | |
775 | ||
776 | k = key_new(KEY_UNSPEC); | |
777 | if (!load_private_key(filename, "", k, NULL)) { | |
778 | if (options.batch_mode) { | |
779 | key_free(k); | |
780 | return 0; | |
781 | } | |
782 | snprintf(prompt, sizeof prompt, | |
783 | "Enter passphrase for key '%.100s': ", filename); | |
784 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
785 | passphrase = read_passphrase(prompt, 0); | |
786 | if (strcmp(passphrase, "") != 0) { | |
787 | success = load_private_key(filename, passphrase, k, NULL); | |
788 | try_next = 0; | |
789 | } else { | |
790 | debug2("no passphrase given, try next key"); | |
791 | try_next = 1; | |
792 | } | |
793 | memset(passphrase, 0, strlen(passphrase)); | |
794 | xfree(passphrase); | |
795 | if (success || try_next) | |
796 | break; | |
797 | debug2("bad passphrase given, try again..."); | |
798 | } | |
799 | if (!success) { | |
800 | key_free(k); | |
801 | return 0; | |
802 | } | |
803 | } | |
804 | ret = sign_and_send_pubkey(authctxt, k, key_sign_cb); | |
805 | key_free(k); | |
806 | return ret; | |
807 | } | |
808 | ||
809 | /* sign callback */ | |
810 | int agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp, | |
811 | u_char *data, int datalen) | |
812 | { | |
813 | return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); | |
814 | } | |
815 | ||
816 | int | |
817 | userauth_pubkey_agent(Authctxt *authctxt) | |
818 | { | |
819 | static int called = 0; | |
820 | int ret = 0; | |
821 | char *comment; | |
822 | Key *k; | |
823 | ||
824 | if (called == 0) { | |
825 | if (ssh_get_num_identities(authctxt->agent, 2) == 0) | |
826 | debug2("userauth_pubkey_agent: no keys at all"); | |
827 | called = 1; | |
828 | } | |
829 | k = ssh_get_next_identity(authctxt->agent, &comment, 2); | |
830 | if (k == NULL) { | |
831 | debug2("userauth_pubkey_agent: no more keys"); | |
832 | } else { | |
833 | debug("userauth_pubkey_agent: trying agent key %s", comment); | |
834 | xfree(comment); | |
835 | ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb); | |
836 | key_free(k); | |
837 | } | |
838 | if (ret == 0) | |
839 | debug2("userauth_pubkey_agent: no message sent"); | |
840 | return ret; | |
841 | } | |
842 | ||
843 | int | |
844 | userauth_pubkey(Authctxt *authctxt) | |
845 | { | |
846 | static int idx = 0; | |
847 | int sent = 0; | |
848 | ||
849 | if (authctxt->agent != NULL) { | |
850 | do { | |
851 | sent = userauth_pubkey_agent(authctxt); | |
852 | } while(!sent && authctxt->agent->howmany > 0); | |
853 | } | |
854 | while (!sent && idx < options.num_identity_files) { | |
855 | if (options.identity_files_type[idx] != KEY_RSA1) | |
856 | sent = userauth_pubkey_identity(authctxt, | |
857 | options.identity_files[idx]); | |
858 | idx++; | |
859 | } | |
860 | return sent; | |
861 | } | |
862 | ||
863 | /* | |
864 | * Send userauth request message specifying keyboard-interactive method. | |
865 | */ | |
866 | int | |
867 | userauth_kbdint(Authctxt *authctxt) | |
868 | { | |
869 | static int attempt = 0; | |
870 | ||
871 | if (attempt++ >= options.number_of_password_prompts) | |
872 | return 0; | |
873 | ||
874 | debug2("userauth_kbdint"); | |
875 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
876 | packet_put_cstring(authctxt->server_user); | |
877 | packet_put_cstring(authctxt->service); | |
878 | packet_put_cstring(authctxt->method->name); | |
879 | packet_put_cstring(""); /* lang */ | |
880 | packet_put_cstring(options.kbd_interactive_devices ? | |
881 | options.kbd_interactive_devices : ""); | |
882 | packet_send(); | |
883 | packet_write_wait(); | |
884 | ||
885 | dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); | |
886 | return 1; | |
887 | } | |
888 | ||
889 | /* | |
890 | * parse INFO_REQUEST, prompt user and send INFO_RESPONSE | |
891 | */ | |
892 | void | |
893 | input_userauth_info_req(int type, int plen, void *ctxt) | |
894 | { | |
895 | Authctxt *authctxt = ctxt; | |
896 | char *name, *inst, *lang, *prompt, *response; | |
897 | u_int num_prompts, i; | |
898 | int echo = 0; | |
899 | ||
900 | debug2("input_userauth_info_req"); | |
901 | ||
902 | if (authctxt == NULL) | |
903 | fatal("input_userauth_info_req: no authentication context"); | |
904 | ||
905 | name = packet_get_string(NULL); | |
906 | inst = packet_get_string(NULL); | |
907 | lang = packet_get_string(NULL); | |
908 | if (strlen(name) > 0) | |
909 | cli_mesg(name); | |
910 | if (strlen(inst) > 0) | |
911 | cli_mesg(inst); | |
912 | xfree(name); | |
913 | xfree(inst); | |
914 | xfree(lang); | |
915 | ||
916 | num_prompts = packet_get_int(); | |
917 | /* | |
918 | * Begin to build info response packet based on prompts requested. | |
919 | * We commit to providing the correct number of responses, so if | |
920 | * further on we run into a problem that prevents this, we have to | |
921 | * be sure and clean this up and send a correct error response. | |
922 | */ | |
923 | packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); | |
924 | packet_put_int(num_prompts); | |
925 | ||
926 | for (i = 0; i < num_prompts; i++) { | |
927 | prompt = packet_get_string(NULL); | |
928 | echo = packet_get_char(); | |
929 | ||
930 | response = cli_prompt(prompt, echo); | |
931 | ||
932 | packet_put_cstring(response); | |
933 | memset(response, 0, strlen(response)); | |
934 | xfree(response); | |
935 | xfree(prompt); | |
936 | } | |
937 | packet_done(); /* done with parsing incoming message. */ | |
938 | ||
939 | packet_inject_ignore(64); | |
940 | packet_send(); | |
941 | packet_write_wait(); | |
942 | } | |
943 | ||
944 | /* find auth method */ | |
945 | ||
946 | #define DELIM "," | |
947 | ||
948 | static char *def_authlist = "publickey,password"; | |
949 | static char *authlist_current = NULL; /* clean copy used for comparison */ | |
950 | static char *authname_current = NULL; /* last used auth method */ | |
951 | static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */ | |
952 | static char *authlist_state = NULL; /* state variable for strtok_r() */ | |
953 | ||
954 | /* | |
955 | * Before starting to use a new authentication method list sent by the | |
956 | * server, reset internal variables. This should also be called when | |
957 | * finished processing server list to free resources. | |
958 | */ | |
959 | void | |
960 | authmethod_clear(void) | |
961 | { | |
962 | if (authlist_current != NULL) { | |
963 | xfree(authlist_current); | |
964 | authlist_current = NULL; | |
965 | } | |
966 | if (authlist_working != NULL) { | |
967 | xfree(authlist_working); | |
968 | authlist_working = NULL; | |
969 | } | |
970 | if (authname_current != NULL) { | |
971 | xfree(authname_current); | |
972 | authname_current = NULL; | |
973 | } | |
974 | if (authlist_state != NULL) | |
975 | authlist_state = NULL; | |
976 | return; | |
977 | } | |
978 | ||
979 | /* | |
980 | * given auth method name, if configurable options permit this method fill | |
981 | * in auth_ident field and return true, otherwise return false. | |
982 | */ | |
983 | int | |
984 | authmethod_is_enabled(Authmethod *method) | |
985 | { | |
986 | if (method == NULL) | |
987 | return 0; | |
988 | /* return false if options indicate this method is disabled */ | |
989 | if (method->enabled == NULL || *method->enabled == 0) | |
990 | return 0; | |
991 | /* return false if batch mode is enabled but method needs interactive mode */ | |
992 | if (method->batch_flag != NULL && *method->batch_flag != 0) | |
993 | return 0; | |
994 | return 1; | |
995 | } | |
996 | ||
997 | Authmethod * | |
998 | authmethod_lookup(const char *name) | |
999 | { | |
1000 | Authmethod *method = NULL; | |
1001 | if (name != NULL) | |
1002 | for (method = authmethods; method->name != NULL; method++) | |
1003 | if (strcmp(name, method->name) == 0) | |
1004 | return method; | |
1005 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
1006 | return NULL; | |
1007 | } | |
1008 | ||
1009 | /* | |
1010 | * Given the authentication method list sent by the server, return the | |
1011 | * next method we should try. If the server initially sends a nil list, | |
1012 | * use a built-in default list. If the server sends a nil list after | |
1013 | * previously sending a valid list, continue using the list originally | |
1014 | * sent. | |
1015 | */ | |
1016 | ||
1017 | Authmethod * | |
1018 | authmethod_get(char *authlist) | |
1019 | { | |
1020 | char *name = NULL, *authname_old; | |
1021 | Authmethod *method = NULL; | |
1022 | ||
1023 | /* Use a suitable default if we're passed a nil list. */ | |
1024 | if (authlist == NULL || strlen(authlist) == 0) | |
1025 | authlist = def_authlist; | |
1026 | ||
1027 | if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) { | |
1028 | /* start over if passed a different list */ | |
1029 | debug3("start over, passed a different list"); | |
1030 | authmethod_clear(); | |
1031 | authlist_current = xstrdup(authlist); | |
1032 | authlist_working = xstrdup(authlist); | |
1033 | name = strtok_r(authlist_working, DELIM, &authlist_state); | |
1034 | } else { | |
1035 | /* | |
1036 | * try to use previously used authentication method | |
1037 | * or continue to use previously passed list | |
1038 | */ | |
1039 | name = (authname_current != NULL) ? | |
1040 | authname_current : strtok_r(NULL, DELIM, &authlist_state); | |
1041 | } | |
1042 | ||
1043 | while (name != NULL) { | |
1044 | debug3("authmethod_lookup %s", name); | |
1045 | method = authmethod_lookup(name); | |
1046 | if (method != NULL && authmethod_is_enabled(method)) { | |
1047 | debug3("authmethod_is_enabled %s", name); | |
1048 | break; | |
1049 | } | |
1050 | name = strtok_r(NULL, DELIM, &authlist_state); | |
1051 | method = NULL; | |
1052 | } | |
1053 | ||
1054 | authname_old = authname_current; | |
1055 | if (method != NULL) { | |
1056 | debug("next auth method to try is %s", name); | |
1057 | authname_current = xstrdup(name); | |
1058 | } else { | |
1059 | debug("no more auth methods to try"); | |
1060 | authname_current = NULL; | |
1061 | } | |
1062 | ||
1063 | if (authname_old != NULL) | |
1064 | xfree(authname_old); | |
1065 | ||
1066 | return (method); | |
1067 | } |