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a306f2dd | 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. | |
a306f2dd | 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" | |
fa08c86b | 26 | RCSID("$OpenBSD: sshconnect2.c,v 1.28 2000/11/12 19:50:38 markus Exp $"); |
a306f2dd | 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" | |
a306f2dd | 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" | |
a306f2dd | 48 | #include "sshconnect.h" |
49 | #include "authfile.h" | |
94ec8c6b | 50 | #include "cli.h" |
188adeb2 | 51 | #include "dispatch.h" |
2e73a022 | 52 | #include "authfd.h" |
a306f2dd | 53 | |
94ec8c6b | 54 | void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); |
55 | void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); | |
56 | ||
a306f2dd | 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 | |
94ec8c6b | 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 == NULL) { | |
78 | if (options.cipher == SSH_CIPHER_3DES) { | |
79 | options.ciphers = "3des-cbc"; | |
80 | } else if (options.cipher == SSH_CIPHER_BLOWFISH) { | |
81 | options.ciphers = "blowfish-cbc"; | |
82 | } else if (options.cipher == SSH_CIPHER_DES) { | |
83 | fatal("cipher DES not supported for protocol version 2"); | |
84 | } | |
85 | } | |
86 | if (options.ciphers != NULL) { | |
87 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
88 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
89 | } | |
90 | if (options.compression) { | |
91 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib"; | |
92 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; | |
93 | } else { | |
94 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none"; | |
95 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
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) | |
a306f2dd | 154 | { |
188adeb2 | 155 | #ifdef DEBUG_KEXDH |
156 | int i; | |
157 | #endif | |
71276795 | 158 | int plen, dlen; |
a306f2dd | 159 | unsigned int klen, kout; |
a306f2dd | 160 | char *signature = NULL; |
161 | unsigned int slen; | |
162 | char *server_host_key_blob = NULL; | |
163 | Key *server_host_key; | |
164 | unsigned int sbloblen; | |
165 | DH *dh; | |
166 | BIGNUM *dh_server_pub = 0; | |
167 | BIGNUM *shared_secret = 0; | |
a306f2dd | 168 | unsigned char *kbuf; |
169 | unsigned char *hash; | |
170 | ||
a306f2dd | 171 | debug("Sending SSH2_MSG_KEXDH_INIT."); |
a306f2dd | 172 | /* generate and send 'e', client DH public key */ |
173 | dh = dh_new_group1(); | |
174 | packet_start(SSH2_MSG_KEXDH_INIT); | |
175 | packet_put_bignum2(dh->pub_key); | |
176 | packet_send(); | |
177 | packet_write_wait(); | |
178 | ||
179 | #ifdef DEBUG_KEXDH | |
180 | fprintf(stderr, "\np= "); | |
188adeb2 | 181 | BN_print_fp(stderr, dh->p); |
a306f2dd | 182 | fprintf(stderr, "\ng= "); |
188adeb2 | 183 | BN_print_fp(stderr, dh->g); |
a306f2dd | 184 | fprintf(stderr, "\npub= "); |
188adeb2 | 185 | BN_print_fp(stderr, dh->pub_key); |
a306f2dd | 186 | fprintf(stderr, "\n"); |
187 | DHparams_print_fp(stderr, dh); | |
188 | #endif | |
189 | ||
190 | debug("Wait SSH2_MSG_KEXDH_REPLY."); | |
191 | ||
71276795 | 192 | packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY); |
a306f2dd | 193 | |
194 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
195 | ||
196 | /* key, cert */ | |
197 | server_host_key_blob = packet_get_string(&sbloblen); | |
fa08c86b | 198 | server_host_key = key_from_blob(server_host_key_blob, sbloblen); |
a306f2dd | 199 | if (server_host_key == NULL) |
200 | fatal("cannot decode server_host_key_blob"); | |
201 | ||
202 | check_host_key(host, hostaddr, server_host_key, | |
94ec8c6b | 203 | options.user_hostfile2, options.system_hostfile2); |
a306f2dd | 204 | |
205 | /* DH paramter f, server public DH key */ | |
206 | dh_server_pub = BN_new(); | |
207 | if (dh_server_pub == NULL) | |
208 | fatal("dh_server_pub == NULL"); | |
209 | packet_get_bignum2(dh_server_pub, &dlen); | |
210 | ||
211 | #ifdef DEBUG_KEXDH | |
212 | fprintf(stderr, "\ndh_server_pub= "); | |
188adeb2 | 213 | BN_print_fp(stderr, dh_server_pub); |
a306f2dd | 214 | fprintf(stderr, "\n"); |
215 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
216 | #endif | |
217 | ||
218 | /* signed H */ | |
219 | signature = packet_get_string(&slen); | |
220 | packet_done(); | |
221 | ||
222 | if (!dh_pub_is_valid(dh, dh_server_pub)) | |
223 | packet_disconnect("bad server public DH value"); | |
224 | ||
225 | klen = DH_size(dh); | |
226 | kbuf = xmalloc(klen); | |
227 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
228 | #ifdef DEBUG_KEXDH | |
229 | debug("shared secret: len %d/%d", klen, kout); | |
230 | fprintf(stderr, "shared secret == "); | |
231 | for (i = 0; i< kout; i++) | |
232 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
233 | fprintf(stderr, "\n"); | |
234 | #endif | |
235 | shared_secret = BN_new(); | |
236 | ||
237 | BN_bin2bn(kbuf, kout, shared_secret); | |
238 | memset(kbuf, 0, klen); | |
239 | xfree(kbuf); | |
240 | ||
241 | /* calc and verify H */ | |
242 | hash = kex_hash( | |
243 | client_version_string, | |
244 | server_version_string, | |
245 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
246 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
247 | server_host_key_blob, sbloblen, | |
248 | dh->pub_key, | |
249 | dh_server_pub, | |
250 | shared_secret | |
251 | ); | |
252 | xfree(server_host_key_blob); | |
71276795 | 253 | DH_free(dh); |
a306f2dd | 254 | #ifdef DEBUG_KEXDH |
255 | fprintf(stderr, "hash == "); | |
256 | for (i = 0; i< 20; i++) | |
257 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
258 | fprintf(stderr, "\n"); | |
259 | #endif | |
fa08c86b | 260 | if (key_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1) |
261 | fatal("key_verify failed for server_host_key"); | |
a306f2dd | 262 | key_free(server_host_key); |
263 | ||
264 | kex_derive_keys(kex, hash, shared_secret); | |
265 | packet_set_kex(kex); | |
266 | ||
a306f2dd | 267 | /* save session id */ |
268 | session_id2_len = 20; | |
269 | session_id2 = xmalloc(session_id2_len); | |
270 | memcpy(session_id2, hash, session_id2_len); | |
71276795 | 271 | } |
272 | ||
94ec8c6b | 273 | /* diffie-hellman-group-exchange-sha1 */ |
274 | ||
275 | /* | |
276 | * Estimates the group order for a Diffie-Hellman group that has an | |
277 | * attack complexity approximately the same as O(2**bits). Estimate | |
278 | * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))) | |
279 | */ | |
280 | ||
281 | int | |
282 | dh_estimate(int bits) | |
283 | { | |
284 | ||
285 | if (bits < 64) | |
286 | return (512); /* O(2**63) */ | |
287 | if (bits < 128) | |
288 | return (1024); /* O(2**86) */ | |
289 | if (bits < 192) | |
290 | return (2048); /* O(2**116) */ | |
291 | return (4096); /* O(2**156) */ | |
292 | } | |
293 | ||
71276795 | 294 | void |
94ec8c6b | 295 | ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr, |
296 | Buffer *client_kexinit, Buffer *server_kexinit) | |
71276795 | 297 | { |
94ec8c6b | 298 | #ifdef DEBUG_KEXDH |
299 | int i; | |
300 | #endif | |
301 | int plen, dlen; | |
302 | unsigned int klen, kout; | |
303 | char *signature = NULL; | |
304 | unsigned int slen, nbits; | |
305 | char *server_host_key_blob = NULL; | |
306 | Key *server_host_key; | |
307 | unsigned int sbloblen; | |
308 | DH *dh; | |
309 | BIGNUM *dh_server_pub = 0; | |
310 | BIGNUM *shared_secret = 0; | |
311 | BIGNUM *p = 0, *g = 0; | |
312 | unsigned char *kbuf; | |
313 | unsigned char *hash; | |
71276795 | 314 | |
94ec8c6b | 315 | nbits = dh_estimate(kex->enc[MODE_OUT].cipher->key_len * 8); |
71276795 | 316 | |
94ec8c6b | 317 | debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST."); |
318 | packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST); | |
319 | packet_put_int(nbits); | |
320 | packet_send(); | |
321 | packet_write_wait(); | |
71276795 | 322 | |
94ec8c6b | 323 | #ifdef DEBUG_KEXDH |
324 | fprintf(stderr, "\nnbits = %d", nbits); | |
325 | #endif | |
71276795 | 326 | |
94ec8c6b | 327 | debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP."); |
71276795 | 328 | |
94ec8c6b | 329 | packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP); |
a306f2dd | 330 | |
94ec8c6b | 331 | debug("Got SSH2_MSG_KEX_DH_GEX_GROUP."); |
a306f2dd | 332 | |
94ec8c6b | 333 | if ((p = BN_new()) == NULL) |
334 | fatal("BN_new"); | |
335 | packet_get_bignum2(p, &dlen); | |
336 | if ((g = BN_new()) == NULL) | |
337 | fatal("BN_new"); | |
338 | packet_get_bignum2(g, &dlen); | |
339 | if ((dh = dh_new_group(g, p)) == NULL) | |
340 | fatal("dh_new_group"); | |
a306f2dd | 341 | |
342 | #ifdef DEBUG_KEXDH | |
94ec8c6b | 343 | fprintf(stderr, "\np= "); |
344 | BN_print_fp(stderr, dh->p); | |
345 | fprintf(stderr, "\ng= "); | |
346 | BN_print_fp(stderr, dh->g); | |
347 | fprintf(stderr, "\npub= "); | |
348 | BN_print_fp(stderr, dh->pub_key); | |
349 | fprintf(stderr, "\n"); | |
350 | DHparams_print_fp(stderr, dh); | |
351 | #endif | |
352 | ||
353 | debug("Sending SSH2_MSG_KEX_DH_GEX_INIT."); | |
354 | /* generate and send 'e', client DH public key */ | |
355 | packet_start(SSH2_MSG_KEX_DH_GEX_INIT); | |
356 | packet_put_bignum2(dh->pub_key); | |
a306f2dd | 357 | packet_send(); |
358 | packet_write_wait(); | |
94ec8c6b | 359 | |
360 | debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY."); | |
361 | ||
362 | packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY); | |
363 | ||
364 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
365 | ||
366 | /* key, cert */ | |
367 | server_host_key_blob = packet_get_string(&sbloblen); | |
fa08c86b | 368 | server_host_key = key_from_blob(server_host_key_blob, sbloblen); |
94ec8c6b | 369 | if (server_host_key == NULL) |
370 | fatal("cannot decode server_host_key_blob"); | |
371 | ||
372 | check_host_key(host, hostaddr, server_host_key, | |
373 | options.user_hostfile2, options.system_hostfile2); | |
374 | ||
375 | /* DH paramter f, server public DH key */ | |
376 | dh_server_pub = BN_new(); | |
377 | if (dh_server_pub == NULL) | |
378 | fatal("dh_server_pub == NULL"); | |
379 | packet_get_bignum2(dh_server_pub, &dlen); | |
380 | ||
381 | #ifdef DEBUG_KEXDH | |
382 | fprintf(stderr, "\ndh_server_pub= "); | |
383 | BN_print_fp(stderr, dh_server_pub); | |
384 | fprintf(stderr, "\n"); | |
385 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
a306f2dd | 386 | #endif |
94ec8c6b | 387 | |
388 | /* signed H */ | |
389 | signature = packet_get_string(&slen); | |
390 | packet_done(); | |
391 | ||
392 | if (!dh_pub_is_valid(dh, dh_server_pub)) | |
393 | packet_disconnect("bad server public DH value"); | |
394 | ||
395 | klen = DH_size(dh); | |
396 | kbuf = xmalloc(klen); | |
397 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
398 | #ifdef DEBUG_KEXDH | |
399 | debug("shared secret: len %d/%d", klen, kout); | |
400 | fprintf(stderr, "shared secret == "); | |
401 | for (i = 0; i< kout; i++) | |
402 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
403 | fprintf(stderr, "\n"); | |
404 | #endif | |
405 | shared_secret = BN_new(); | |
406 | ||
407 | BN_bin2bn(kbuf, kout, shared_secret); | |
408 | memset(kbuf, 0, klen); | |
409 | xfree(kbuf); | |
410 | ||
411 | /* calc and verify H */ | |
412 | hash = kex_hash_gex( | |
413 | client_version_string, | |
414 | server_version_string, | |
415 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
416 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
417 | server_host_key_blob, sbloblen, | |
418 | nbits, dh->p, dh->g, | |
419 | dh->pub_key, | |
420 | dh_server_pub, | |
421 | shared_secret | |
422 | ); | |
423 | xfree(server_host_key_blob); | |
424 | DH_free(dh); | |
425 | #ifdef DEBUG_KEXDH | |
426 | fprintf(stderr, "hash == "); | |
427 | for (i = 0; i< 20; i++) | |
428 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
429 | fprintf(stderr, "\n"); | |
430 | #endif | |
fa08c86b | 431 | if (key_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1) |
432 | fatal("key_verify failed for server_host_key"); | |
94ec8c6b | 433 | key_free(server_host_key); |
434 | ||
435 | kex_derive_keys(kex, hash, shared_secret); | |
436 | packet_set_kex(kex); | |
437 | ||
438 | /* save session id */ | |
439 | session_id2_len = 20; | |
440 | session_id2 = xmalloc(session_id2_len); | |
441 | memcpy(session_id2, hash, session_id2_len); | |
a306f2dd | 442 | } |
71276795 | 443 | |
a306f2dd | 444 | /* |
445 | * Authenticate user | |
446 | */ | |
188adeb2 | 447 | |
448 | typedef struct Authctxt Authctxt; | |
449 | typedef struct Authmethod Authmethod; | |
450 | ||
451 | typedef int sign_cb_fn( | |
452 | Authctxt *authctxt, Key *key, | |
453 | unsigned char **sigp, int *lenp, unsigned char *data, int datalen); | |
454 | ||
455 | struct Authctxt { | |
456 | const char *server_user; | |
457 | const char *host; | |
458 | const char *service; | |
459 | AuthenticationConnection *agent; | |
188adeb2 | 460 | Authmethod *method; |
94ec8c6b | 461 | int success; |
188adeb2 | 462 | }; |
463 | struct Authmethod { | |
464 | char *name; /* string to compare against server's list */ | |
465 | int (*userauth)(Authctxt *authctxt); | |
466 | int *enabled; /* flag in option struct that enables method */ | |
467 | int *batch_flag; /* flag in option struct that disables method */ | |
468 | }; | |
469 | ||
470 | void input_userauth_success(int type, int plen, void *ctxt); | |
471 | void input_userauth_failure(int type, int plen, void *ctxt); | |
472 | void input_userauth_error(int type, int plen, void *ctxt); | |
94ec8c6b | 473 | void input_userauth_info_req(int type, int plen, void *ctxt); |
474 | ||
475 | int userauth_none(Authctxt *authctxt); | |
188adeb2 | 476 | int userauth_pubkey(Authctxt *authctxt); |
477 | int userauth_passwd(Authctxt *authctxt); | |
94ec8c6b | 478 | int userauth_kbdint(Authctxt *authctxt); |
188adeb2 | 479 | |
480 | void authmethod_clear(); | |
94ec8c6b | 481 | Authmethod *authmethod_get(char *authlist); |
482 | Authmethod *authmethod_lookup(const char *name); | |
188adeb2 | 483 | |
484 | Authmethod authmethods[] = { | |
485 | {"publickey", | |
486 | userauth_pubkey, | |
fa08c86b | 487 | &options.pubkey_authentication, |
188adeb2 | 488 | NULL}, |
489 | {"password", | |
490 | userauth_passwd, | |
491 | &options.password_authentication, | |
492 | &options.batch_mode}, | |
94ec8c6b | 493 | {"keyboard-interactive", |
494 | userauth_kbdint, | |
495 | &options.kbd_interactive_authentication, | |
496 | &options.batch_mode}, | |
497 | {"none", | |
498 | userauth_none, | |
499 | NULL, | |
500 | NULL}, | |
188adeb2 | 501 | {NULL, NULL, NULL, NULL} |
502 | }; | |
503 | ||
504 | void | |
505 | ssh_userauth2(const char *server_user, char *host) | |
506 | { | |
507 | Authctxt authctxt; | |
508 | int type; | |
509 | int plen; | |
510 | ||
511 | debug("send SSH2_MSG_SERVICE_REQUEST"); | |
512 | packet_start(SSH2_MSG_SERVICE_REQUEST); | |
513 | packet_put_cstring("ssh-userauth"); | |
514 | packet_send(); | |
515 | packet_write_wait(); | |
516 | type = packet_read(&plen); | |
517 | if (type != SSH2_MSG_SERVICE_ACCEPT) { | |
518 | fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); | |
519 | } | |
520 | if (packet_remaining() > 0) { | |
521 | char *reply = packet_get_string(&plen); | |
522 | debug("service_accept: %s", reply); | |
523 | xfree(reply); | |
524 | packet_done(); | |
525 | } else { | |
526 | debug("buggy server: service_accept w/o service"); | |
527 | } | |
528 | packet_done(); | |
529 | debug("got SSH2_MSG_SERVICE_ACCEPT"); | |
530 | ||
531 | /* setup authentication context */ | |
532 | authctxt.agent = ssh_get_authentication_connection(); | |
533 | authctxt.server_user = server_user; | |
534 | authctxt.host = host; | |
535 | authctxt.service = "ssh-connection"; /* service name */ | |
536 | authctxt.success = 0; | |
94ec8c6b | 537 | authctxt.method = authmethod_lookup("none"); |
538 | if (authctxt.method == NULL) | |
539 | fatal("ssh_userauth2: internal error: cannot send userauth none request"); | |
540 | authmethod_clear(); | |
188adeb2 | 541 | |
542 | /* initial userauth request */ | |
94ec8c6b | 543 | userauth_none(&authctxt); |
188adeb2 | 544 | |
545 | dispatch_init(&input_userauth_error); | |
546 | dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); | |
547 | dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); | |
548 | dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ | |
549 | ||
550 | if (authctxt.agent != NULL) | |
551 | ssh_close_authentication_connection(authctxt.agent); | |
552 | ||
94ec8c6b | 553 | debug("ssh-userauth2 successfull: method %s", authctxt.method->name); |
188adeb2 | 554 | } |
555 | void | |
556 | input_userauth_error(int type, int plen, void *ctxt) | |
557 | { | |
558 | fatal("input_userauth_error: bad message during authentication"); | |
559 | } | |
560 | void | |
561 | input_userauth_success(int type, int plen, void *ctxt) | |
562 | { | |
563 | Authctxt *authctxt = ctxt; | |
564 | if (authctxt == NULL) | |
565 | fatal("input_userauth_success: no authentication context"); | |
566 | authctxt->success = 1; /* break out */ | |
567 | } | |
568 | void | |
569 | input_userauth_failure(int type, int plen, void *ctxt) | |
570 | { | |
571 | Authmethod *method = NULL; | |
572 | Authctxt *authctxt = ctxt; | |
573 | char *authlist = NULL; | |
574 | int partial; | |
188adeb2 | 575 | |
576 | if (authctxt == NULL) | |
577 | fatal("input_userauth_failure: no authentication context"); | |
578 | ||
94ec8c6b | 579 | authlist = packet_get_string(NULL); |
188adeb2 | 580 | partial = packet_get_char(); |
581 | packet_done(); | |
582 | ||
583 | if (partial != 0) | |
584 | debug("partial success"); | |
585 | debug("authentications that can continue: %s", authlist); | |
586 | ||
587 | for (;;) { | |
188adeb2 | 588 | method = authmethod_get(authlist); |
589 | if (method == NULL) | |
590 | fatal("Unable to find an authentication method"); | |
94ec8c6b | 591 | authctxt->method = method; |
188adeb2 | 592 | if (method->userauth(authctxt) != 0) { |
94ec8c6b | 593 | debug2("we sent a %s packet, wait for reply", method->name); |
188adeb2 | 594 | break; |
595 | } else { | |
596 | debug2("we did not send a packet, disable method"); | |
597 | method->enabled = NULL; | |
598 | } | |
599 | } | |
600 | xfree(authlist); | |
601 | } | |
602 | ||
94ec8c6b | 603 | int |
604 | userauth_none(Authctxt *authctxt) | |
605 | { | |
606 | /* initial userauth request */ | |
607 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
608 | packet_put_cstring(authctxt->server_user); | |
609 | packet_put_cstring(authctxt->service); | |
610 | packet_put_cstring(authctxt->method->name); | |
611 | packet_send(); | |
612 | packet_write_wait(); | |
613 | return 1; | |
614 | } | |
615 | ||
a306f2dd | 616 | int |
188adeb2 | 617 | userauth_passwd(Authctxt *authctxt) |
a306f2dd | 618 | { |
1d1ffb87 | 619 | static int attempt = 0; |
a306f2dd | 620 | char prompt[80]; |
621 | char *password; | |
622 | ||
fa649821 | 623 | if (attempt++ >= options.number_of_password_prompts) |
1d1ffb87 | 624 | return 0; |
625 | ||
fa649821 | 626 | if(attempt != 1) |
627 | error("Permission denied, please try again."); | |
628 | ||
a306f2dd | 629 | snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ", |
188adeb2 | 630 | authctxt->server_user, authctxt->host); |
a306f2dd | 631 | password = read_passphrase(prompt, 0); |
632 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
188adeb2 | 633 | packet_put_cstring(authctxt->server_user); |
634 | packet_put_cstring(authctxt->service); | |
94ec8c6b | 635 | packet_put_cstring(authctxt->method->name); |
a306f2dd | 636 | packet_put_char(0); |
637 | packet_put_cstring(password); | |
638 | memset(password, 0, strlen(password)); | |
639 | xfree(password); | |
640 | packet_send(); | |
641 | packet_write_wait(); | |
642 | return 1; | |
643 | } | |
644 | ||
2e73a022 | 645 | int |
188adeb2 | 646 | sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) |
a306f2dd | 647 | { |
648 | Buffer b; | |
a306f2dd | 649 | unsigned char *blob, *signature; |
650 | int bloblen, slen; | |
74fc9186 | 651 | int skip = 0; |
2e73a022 | 652 | int ret = -1; |
94ec8c6b | 653 | int have_sig = 1; |
a306f2dd | 654 | |
fa08c86b | 655 | if (key_to_blob(k, &blob, &bloblen) == 0) { |
656 | /* we cannot handle this key */ | |
657 | return 0; | |
658 | } | |
a306f2dd | 659 | /* data to be signed */ |
660 | buffer_init(&b); | |
33de75a3 | 661 | if (datafellows & SSH_OLD_SESSIONID) { |
74fc9186 | 662 | buffer_append(&b, session_id2, session_id2_len); |
663 | skip = session_id2_len; | |
33de75a3 | 664 | } else { |
665 | buffer_put_string(&b, session_id2, session_id2_len); | |
666 | skip = buffer_len(&b); | |
74fc9186 | 667 | } |
a306f2dd | 668 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
188adeb2 | 669 | buffer_put_cstring(&b, authctxt->server_user); |
d0c832f3 | 670 | buffer_put_cstring(&b, |
671 | datafellows & SSH_BUG_PUBKEYAUTH ? | |
672 | "ssh-userauth" : | |
188adeb2 | 673 | authctxt->service); |
94ec8c6b | 674 | buffer_put_cstring(&b, authctxt->method->name); |
675 | buffer_put_char(&b, have_sig); | |
fa08c86b | 676 | buffer_put_cstring(&b, key_ssh_name(k)); |
a306f2dd | 677 | buffer_put_string(&b, blob, bloblen); |
a306f2dd | 678 | |
679 | /* generate signature */ | |
188adeb2 | 680 | ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); |
2e73a022 | 681 | if (ret == -1) { |
682 | xfree(blob); | |
683 | buffer_free(&b); | |
684 | return 0; | |
685 | } | |
fa08c86b | 686 | #ifdef DEBUG_PK |
a306f2dd | 687 | buffer_dump(&b); |
688 | #endif | |
d0c832f3 | 689 | if (datafellows & SSH_BUG_PUBKEYAUTH) { |
d0c832f3 | 690 | buffer_clear(&b); |
691 | buffer_append(&b, session_id2, session_id2_len); | |
692 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
188adeb2 | 693 | buffer_put_cstring(&b, authctxt->server_user); |
694 | buffer_put_cstring(&b, authctxt->service); | |
94ec8c6b | 695 | buffer_put_cstring(&b, authctxt->method->name); |
696 | buffer_put_char(&b, have_sig); | |
fa08c86b | 697 | buffer_put_cstring(&b, key_ssh_name(k)); |
d0c832f3 | 698 | buffer_put_string(&b, blob, bloblen); |
699 | } | |
700 | xfree(blob); | |
a306f2dd | 701 | /* append signature */ |
702 | buffer_put_string(&b, signature, slen); | |
703 | xfree(signature); | |
704 | ||
705 | /* skip session id and packet type */ | |
74fc9186 | 706 | if (buffer_len(&b) < skip + 1) |
188adeb2 | 707 | fatal("userauth_pubkey: internal error"); |
74fc9186 | 708 | buffer_consume(&b, skip + 1); |
a306f2dd | 709 | |
710 | /* put remaining data from buffer into packet */ | |
711 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
712 | packet_put_raw(buffer_ptr(&b), buffer_len(&b)); | |
713 | buffer_free(&b); | |
714 | ||
715 | /* send */ | |
716 | packet_send(); | |
717 | packet_write_wait(); | |
2e73a022 | 718 | |
719 | return 1; | |
4c8722d9 | 720 | } |
721 | ||
188adeb2 | 722 | /* sign callback */ |
fa08c86b | 723 | int key_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp, |
188adeb2 | 724 | unsigned char *data, int datalen) |
725 | { | |
fa08c86b | 726 | return key_sign(key, sigp, lenp, data, datalen); |
188adeb2 | 727 | } |
728 | ||
4c8722d9 | 729 | int |
188adeb2 | 730 | userauth_pubkey_identity(Authctxt *authctxt, char *filename) |
4c8722d9 | 731 | { |
732 | Key *k; | |
188adeb2 | 733 | int i, ret, try_next; |
4c8722d9 | 734 | struct stat st; |
735 | ||
736 | if (stat(filename, &st) != 0) { | |
737 | debug("key does not exist: %s", filename); | |
738 | return 0; | |
739 | } | |
740 | debug("try pubkey: %s", filename); | |
741 | ||
fa08c86b | 742 | k = key_new(KEY_UNSPEC); |
4c8722d9 | 743 | if (!load_private_key(filename, "", k, NULL)) { |
744 | int success = 0; | |
745 | char *passphrase; | |
746 | char prompt[300]; | |
747 | snprintf(prompt, sizeof prompt, | |
fa08c86b | 748 | "Enter passphrase for key '%.100s': ", filename); |
188adeb2 | 749 | for (i = 0; i < options.number_of_password_prompts; i++) { |
750 | passphrase = read_passphrase(prompt, 0); | |
751 | if (strcmp(passphrase, "") != 0) { | |
752 | success = load_private_key(filename, passphrase, k, NULL); | |
753 | try_next = 0; | |
754 | } else { | |
755 | debug2("no passphrase given, try next key"); | |
756 | try_next = 1; | |
757 | } | |
758 | memset(passphrase, 0, strlen(passphrase)); | |
759 | xfree(passphrase); | |
760 | if (success || try_next) | |
761 | break; | |
762 | debug2("bad passphrase given, try again..."); | |
763 | } | |
4c8722d9 | 764 | if (!success) { |
765 | key_free(k); | |
766 | return 0; | |
767 | } | |
768 | } | |
fa08c86b | 769 | ret = sign_and_send_pubkey(authctxt, k, key_sign_cb); |
2e73a022 | 770 | key_free(k); |
771 | return ret; | |
772 | } | |
773 | ||
188adeb2 | 774 | /* sign callback */ |
775 | int agent_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp, | |
2e73a022 | 776 | unsigned char *data, int datalen) |
777 | { | |
188adeb2 | 778 | return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); |
2e73a022 | 779 | } |
780 | ||
781 | int | |
188adeb2 | 782 | userauth_pubkey_agent(Authctxt *authctxt) |
2e73a022 | 783 | { |
784 | static int called = 0; | |
fa08c86b | 785 | int ret = 0; |
2e73a022 | 786 | char *comment; |
787 | Key *k; | |
2e73a022 | 788 | |
789 | if (called == 0) { | |
fa08c86b | 790 | if (ssh_get_num_identities(authctxt->agent, 2) == 0) |
791 | debug2("userauth_pubkey_agent: no keys at all"); | |
188adeb2 | 792 | called = 1; |
2e73a022 | 793 | } |
fa08c86b | 794 | k = ssh_get_next_identity(authctxt->agent, &comment, 2); |
188adeb2 | 795 | if (k == NULL) { |
fa08c86b | 796 | debug2("userauth_pubkey_agent: no more keys"); |
797 | } else { | |
798 | debug("userauth_pubkey_agent: trying agent key %s", comment); | |
799 | xfree(comment); | |
800 | ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb); | |
801 | key_free(k); | |
188adeb2 | 802 | } |
fa08c86b | 803 | if (ret == 0) |
804 | debug2("userauth_pubkey_agent: no message sent"); | |
2e73a022 | 805 | return ret; |
a306f2dd | 806 | } |
807 | ||
188adeb2 | 808 | int |
809 | userauth_pubkey(Authctxt *authctxt) | |
a306f2dd | 810 | { |
188adeb2 | 811 | static int idx = 0; |
812 | int sent = 0; | |
813 | ||
fa08c86b | 814 | if (authctxt->agent != NULL) { |
815 | do { | |
816 | sent = userauth_pubkey_agent(authctxt); | |
817 | } while(!sent && authctxt->agent->howmany > 0); | |
818 | } | |
819 | while (!sent && idx < options.num_identity_files) { | |
820 | if (options.identity_files_type[idx] != KEY_RSA1) | |
821 | sent = userauth_pubkey_identity(authctxt, | |
822 | options.identity_files[idx]); | |
823 | idx++; | |
824 | } | |
188adeb2 | 825 | return sent; |
826 | } | |
a306f2dd | 827 | |
94ec8c6b | 828 | /* |
829 | * Send userauth request message specifying keyboard-interactive method. | |
830 | */ | |
831 | int | |
832 | userauth_kbdint(Authctxt *authctxt) | |
833 | { | |
834 | static int attempt = 0; | |
835 | ||
836 | if (attempt++ >= options.number_of_password_prompts) | |
837 | return 0; | |
838 | ||
839 | debug2("userauth_kbdint"); | |
840 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
841 | packet_put_cstring(authctxt->server_user); | |
842 | packet_put_cstring(authctxt->service); | |
843 | packet_put_cstring(authctxt->method->name); | |
844 | packet_put_cstring(""); /* lang */ | |
845 | packet_put_cstring(options.kbd_interactive_devices ? | |
846 | options.kbd_interactive_devices : ""); | |
847 | packet_send(); | |
848 | packet_write_wait(); | |
849 | ||
850 | dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); | |
851 | return 1; | |
852 | } | |
853 | ||
854 | /* | |
855 | * parse SSH2_MSG_USERAUTH_INFO_REQUEST, prompt user and send | |
856 | * SSH2_MSG_USERAUTH_INFO_RESPONSE | |
857 | */ | |
858 | void | |
859 | input_userauth_info_req(int type, int plen, void *ctxt) | |
860 | { | |
861 | Authctxt *authctxt = ctxt; | |
862 | char *name = NULL; | |
863 | char *inst = NULL; | |
864 | char *lang = NULL; | |
865 | char *prompt = NULL; | |
866 | char *response = NULL; | |
867 | unsigned int num_prompts, i; | |
868 | int echo = 0; | |
869 | ||
870 | debug2("input_userauth_info_req"); | |
871 | ||
872 | if (authctxt == NULL) | |
873 | fatal("input_userauth_info_req: no authentication context"); | |
874 | ||
875 | name = packet_get_string(NULL); | |
876 | inst = packet_get_string(NULL); | |
877 | lang = packet_get_string(NULL); | |
878 | ||
879 | if (strlen(name) > 0) | |
880 | cli_mesg(name); | |
881 | xfree(name); | |
882 | ||
883 | if (strlen(inst) > 0) | |
884 | cli_mesg(inst); | |
885 | xfree(inst); | |
886 | xfree(lang); /* unused */ | |
887 | ||
888 | num_prompts = packet_get_int(); | |
889 | /* | |
890 | * Begin to build info response packet based on prompts requested. | |
891 | * We commit to providing the correct number of responses, so if | |
892 | * further on we run into a problem that prevents this, we have to | |
893 | * be sure and clean this up and send a correct error response. | |
894 | */ | |
895 | packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); | |
896 | packet_put_int(num_prompts); | |
897 | ||
898 | for (i = 0; i < num_prompts; i++) { | |
899 | prompt = packet_get_string(NULL); | |
900 | echo = packet_get_char(); | |
901 | ||
902 | response = cli_prompt(prompt, echo); | |
903 | ||
904 | packet_put_cstring(response); | |
905 | memset(response, 0, strlen(response)); | |
906 | xfree(response); | |
907 | xfree(prompt); | |
908 | } | |
909 | packet_done(); /* done with parsing incoming message. */ | |
910 | ||
911 | packet_send(); | |
912 | packet_write_wait(); | |
913 | } | |
a306f2dd | 914 | |
188adeb2 | 915 | /* find auth method */ |
916 | ||
917 | #define DELIM "," | |
918 | ||
919 | static char *def_authlist = "publickey,password"; | |
920 | static char *authlist_current = NULL; /* clean copy used for comparison */ | |
921 | static char *authname_current = NULL; /* last used auth method */ | |
922 | static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */ | |
923 | static char *authlist_state = NULL; /* state variable for strtok_r() */ | |
924 | ||
925 | /* | |
926 | * Before starting to use a new authentication method list sent by the | |
927 | * server, reset internal variables. This should also be called when | |
928 | * finished processing server list to free resources. | |
929 | */ | |
930 | void | |
931 | authmethod_clear() | |
932 | { | |
933 | if (authlist_current != NULL) { | |
934 | xfree(authlist_current); | |
935 | authlist_current = NULL; | |
a306f2dd | 936 | } |
188adeb2 | 937 | if (authlist_working != NULL) { |
938 | xfree(authlist_working); | |
939 | authlist_working = NULL; | |
a306f2dd | 940 | } |
188adeb2 | 941 | if (authname_current != NULL) { |
942 | xfree(authname_current); | |
943 | authlist_state = NULL; | |
944 | } | |
945 | if (authlist_state != NULL) | |
946 | authlist_state = NULL; | |
947 | return; | |
948 | } | |
a306f2dd | 949 | |
188adeb2 | 950 | /* |
951 | * given auth method name, if configurable options permit this method fill | |
952 | * in auth_ident field and return true, otherwise return false. | |
953 | */ | |
954 | int | |
955 | authmethod_is_enabled(Authmethod *method) | |
956 | { | |
957 | if (method == NULL) | |
958 | return 0; | |
959 | /* return false if options indicate this method is disabled */ | |
960 | if (method->enabled == NULL || *method->enabled == 0) | |
961 | return 0; | |
962 | /* return false if batch mode is enabled but method needs interactive mode */ | |
963 | if (method->batch_flag != NULL && *method->batch_flag != 0) | |
964 | return 0; | |
965 | return 1; | |
966 | } | |
a306f2dd | 967 | |
188adeb2 | 968 | Authmethod * |
969 | authmethod_lookup(const char *name) | |
970 | { | |
971 | Authmethod *method = NULL; | |
972 | if (name != NULL) | |
973 | for (method = authmethods; method->name != NULL; method++) | |
974 | if (strcmp(name, method->name) == 0) | |
975 | return method; | |
976 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
977 | return NULL; | |
978 | } | |
979 | ||
980 | /* | |
981 | * Given the authentication method list sent by the server, return the | |
982 | * next method we should try. If the server initially sends a nil list, | |
983 | * use a built-in default list. If the server sends a nil list after | |
984 | * previously sending a valid list, continue using the list originally | |
985 | * sent. | |
986 | */ | |
987 | ||
988 | Authmethod * | |
989 | authmethod_get(char *authlist) | |
990 | { | |
a22aff1f | 991 | char *name = NULL, *authname_old; |
188adeb2 | 992 | Authmethod *method = NULL; |
993 | ||
994 | /* Use a suitable default if we're passed a nil list. */ | |
995 | if (authlist == NULL || strlen(authlist) == 0) | |
996 | authlist = def_authlist; | |
997 | ||
998 | if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) { | |
999 | /* start over if passed a different list */ | |
94ec8c6b | 1000 | debug3("start over, passed a different list"); |
188adeb2 | 1001 | authmethod_clear(); |
1002 | authlist_current = xstrdup(authlist); | |
1003 | authlist_working = xstrdup(authlist); | |
1004 | name = strtok_r(authlist_working, DELIM, &authlist_state); | |
1005 | } else { | |
1006 | /* | |
1007 | * try to use previously used authentication method | |
1008 | * or continue to use previously passed list | |
1009 | */ | |
1010 | name = (authname_current != NULL) ? | |
1011 | authname_current : strtok_r(NULL, DELIM, &authlist_state); | |
1012 | } | |
1013 | ||
1014 | while (name != NULL) { | |
94ec8c6b | 1015 | debug3("authmethod_lookup %s", name); |
188adeb2 | 1016 | method = authmethod_lookup(name); |
94ec8c6b | 1017 | if (method != NULL && authmethod_is_enabled(method)) { |
1018 | debug3("authmethod_is_enabled %s", name); | |
a306f2dd | 1019 | break; |
94ec8c6b | 1020 | } |
188adeb2 | 1021 | name = strtok_r(NULL, DELIM, &authlist_state); |
94ec8c6b | 1022 | method = NULL; |
188adeb2 | 1023 | } |
1024 | ||
a22aff1f | 1025 | authname_old = authname_current; |
94ec8c6b | 1026 | if (method != NULL) { |
188adeb2 | 1027 | debug("next auth method to try is %s", name); |
1028 | authname_current = xstrdup(name); | |
188adeb2 | 1029 | } else { |
1030 | debug("no more auth methods to try"); | |
1031 | authname_current = NULL; | |
a306f2dd | 1032 | } |
a22aff1f | 1033 | |
1034 | if (authname_old != NULL) | |
1035 | xfree(authname_old); | |
1036 | ||
1037 | return (method); | |
a306f2dd | 1038 | } |