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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" | |
94ec8c6b | 26 | RCSID("$OpenBSD: sshconnect2.c,v 1.25 2000/10/12 09:59:19 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" | |
48 | #include "dsa.h" | |
49 | #include "sshconnect.h" | |
50 | #include "authfile.h" | |
94ec8c6b | 51 | #include "cli.h" |
188adeb2 | 52 | #include "dispatch.h" |
2e73a022 | 53 | #include "authfd.h" |
a306f2dd | 54 | |
94ec8c6b | 55 | void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); |
56 | void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); | |
57 | ||
a306f2dd | 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 | unsigned char *session_id2 = NULL; | |
68 | int session_id2_len = 0; | |
69 | ||
70 | void | |
94ec8c6b | 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 == NULL) { | |
79 | if (options.cipher == SSH_CIPHER_3DES) { | |
80 | options.ciphers = "3des-cbc"; | |
81 | } else if (options.cipher == SSH_CIPHER_BLOWFISH) { | |
82 | options.ciphers = "blowfish-cbc"; | |
83 | } else if (options.cipher == SSH_CIPHER_DES) { | |
84 | fatal("cipher DES not supported for protocol version 2"); | |
85 | } | |
86 | } | |
87 | if (options.ciphers != NULL) { | |
88 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
89 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
90 | } | |
91 | if (options.compression) { | |
92 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib"; | |
93 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; | |
94 | } else { | |
95 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none"; | |
96 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
97 | } | |
98 | ||
99 | /* buffers with raw kexinit messages */ | |
100 | server_kexinit = xmalloc(sizeof(*server_kexinit)); | |
101 | buffer_init(server_kexinit); | |
102 | client_kexinit = kex_init(myproposal); | |
103 | ||
104 | /* algorithm negotiation */ | |
105 | kex_exchange_kexinit(client_kexinit, server_kexinit, sprop); | |
106 | kex = kex_choose_conf(myproposal, sprop, 0); | |
107 | for (i = 0; i < PROPOSAL_MAX; i++) | |
108 | xfree(sprop[i]); | |
109 | ||
110 | /* server authentication and session key agreement */ | |
111 | switch(kex->kex_type) { | |
112 | case DH_GRP1_SHA1: | |
113 | ssh_dh1_client(kex, host, hostaddr, | |
114 | client_kexinit, server_kexinit); | |
115 | break; | |
116 | case DH_GEX_SHA1: | |
117 | ssh_dhgex_client(kex, host, hostaddr, client_kexinit, | |
118 | server_kexinit); | |
119 | break; | |
120 | default: | |
121 | fatal("Unsupported key exchange %d", kex->kex_type); | |
122 | } | |
123 | ||
124 | buffer_free(client_kexinit); | |
125 | buffer_free(server_kexinit); | |
126 | xfree(client_kexinit); | |
127 | xfree(server_kexinit); | |
128 | ||
129 | debug("Wait SSH2_MSG_NEWKEYS."); | |
130 | packet_read_expect(&plen, SSH2_MSG_NEWKEYS); | |
131 | packet_done(); | |
132 | debug("GOT SSH2_MSG_NEWKEYS."); | |
133 | ||
134 | debug("send SSH2_MSG_NEWKEYS."); | |
135 | packet_start(SSH2_MSG_NEWKEYS); | |
136 | packet_send(); | |
137 | packet_write_wait(); | |
138 | debug("done: send SSH2_MSG_NEWKEYS."); | |
139 | ||
140 | #ifdef DEBUG_KEXDH | |
141 | /* send 1st encrypted/maced/compressed message */ | |
142 | packet_start(SSH2_MSG_IGNORE); | |
143 | packet_put_cstring("markus"); | |
144 | packet_send(); | |
145 | packet_write_wait(); | |
146 | #endif | |
147 | debug("done: KEX2."); | |
148 | } | |
149 | ||
150 | /* diffie-hellman-group1-sha1 */ | |
151 | ||
152 | void | |
153 | ssh_dh1_client(Kex *kex, char *host, struct sockaddr *hostaddr, | |
154 | Buffer *client_kexinit, Buffer *server_kexinit) | |
a306f2dd | 155 | { |
188adeb2 | 156 | #ifdef DEBUG_KEXDH |
157 | int i; | |
158 | #endif | |
71276795 | 159 | int plen, dlen; |
a306f2dd | 160 | unsigned int klen, kout; |
a306f2dd | 161 | char *signature = NULL; |
162 | unsigned int slen; | |
163 | char *server_host_key_blob = NULL; | |
164 | Key *server_host_key; | |
165 | unsigned int sbloblen; | |
166 | DH *dh; | |
167 | BIGNUM *dh_server_pub = 0; | |
168 | BIGNUM *shared_secret = 0; | |
a306f2dd | 169 | unsigned char *kbuf; |
170 | unsigned char *hash; | |
171 | ||
a306f2dd | 172 | debug("Sending SSH2_MSG_KEXDH_INIT."); |
a306f2dd | 173 | /* generate and send 'e', client DH public key */ |
174 | dh = dh_new_group1(); | |
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= "); | |
188adeb2 | 182 | BN_print_fp(stderr, dh->p); |
a306f2dd | 183 | fprintf(stderr, "\ng= "); |
188adeb2 | 184 | BN_print_fp(stderr, dh->g); |
a306f2dd | 185 | fprintf(stderr, "\npub= "); |
188adeb2 | 186 | BN_print_fp(stderr, dh->pub_key); |
a306f2dd | 187 | fprintf(stderr, "\n"); |
188 | DHparams_print_fp(stderr, dh); | |
189 | #endif | |
190 | ||
191 | debug("Wait SSH2_MSG_KEXDH_REPLY."); | |
192 | ||
71276795 | 193 | packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY); |
a306f2dd | 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 = dsa_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, | |
94ec8c6b | 204 | options.user_hostfile2, options.system_hostfile2); |
a306f2dd | 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= "); | |
188adeb2 | 214 | BN_print_fp(stderr, dh_server_pub); |
a306f2dd | 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); | |
71276795 | 254 | DH_free(dh); |
a306f2dd | 255 | #ifdef DEBUG_KEXDH |
256 | fprintf(stderr, "hash == "); | |
257 | for (i = 0; i< 20; i++) | |
258 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
259 | fprintf(stderr, "\n"); | |
260 | #endif | |
261 | if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1) | |
262 | fatal("dsa_verify failed for server_host_key"); | |
263 | key_free(server_host_key); | |
264 | ||
265 | kex_derive_keys(kex, hash, shared_secret); | |
266 | packet_set_kex(kex); | |
267 | ||
a306f2dd | 268 | /* save session id */ |
269 | session_id2_len = 20; | |
270 | session_id2 = xmalloc(session_id2_len); | |
271 | memcpy(session_id2, hash, session_id2_len); | |
71276795 | 272 | } |
273 | ||
94ec8c6b | 274 | /* diffie-hellman-group-exchange-sha1 */ |
275 | ||
276 | /* | |
277 | * Estimates the group order for a Diffie-Hellman group that has an | |
278 | * attack complexity approximately the same as O(2**bits). Estimate | |
279 | * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))) | |
280 | */ | |
281 | ||
282 | int | |
283 | dh_estimate(int bits) | |
284 | { | |
285 | ||
286 | if (bits < 64) | |
287 | return (512); /* O(2**63) */ | |
288 | if (bits < 128) | |
289 | return (1024); /* O(2**86) */ | |
290 | if (bits < 192) | |
291 | return (2048); /* O(2**116) */ | |
292 | return (4096); /* O(2**156) */ | |
293 | } | |
294 | ||
71276795 | 295 | void |
94ec8c6b | 296 | ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr, |
297 | Buffer *client_kexinit, Buffer *server_kexinit) | |
71276795 | 298 | { |
94ec8c6b | 299 | #ifdef DEBUG_KEXDH |
300 | int i; | |
301 | #endif | |
302 | int plen, dlen; | |
303 | unsigned int klen, kout; | |
304 | char *signature = NULL; | |
305 | unsigned int slen, nbits; | |
306 | char *server_host_key_blob = NULL; | |
307 | Key *server_host_key; | |
308 | unsigned int sbloblen; | |
309 | DH *dh; | |
310 | BIGNUM *dh_server_pub = 0; | |
311 | BIGNUM *shared_secret = 0; | |
312 | BIGNUM *p = 0, *g = 0; | |
313 | unsigned char *kbuf; | |
314 | unsigned char *hash; | |
71276795 | 315 | |
94ec8c6b | 316 | nbits = dh_estimate(kex->enc[MODE_OUT].cipher->key_len * 8); |
71276795 | 317 | |
94ec8c6b | 318 | debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST."); |
319 | packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST); | |
320 | packet_put_int(nbits); | |
321 | packet_send(); | |
322 | packet_write_wait(); | |
71276795 | 323 | |
94ec8c6b | 324 | #ifdef DEBUG_KEXDH |
325 | fprintf(stderr, "\nnbits = %d", nbits); | |
326 | #endif | |
71276795 | 327 | |
94ec8c6b | 328 | debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP."); |
71276795 | 329 | |
94ec8c6b | 330 | packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP); |
a306f2dd | 331 | |
94ec8c6b | 332 | debug("Got SSH2_MSG_KEX_DH_GEX_GROUP."); |
a306f2dd | 333 | |
94ec8c6b | 334 | if ((p = BN_new()) == NULL) |
335 | fatal("BN_new"); | |
336 | packet_get_bignum2(p, &dlen); | |
337 | if ((g = BN_new()) == NULL) | |
338 | fatal("BN_new"); | |
339 | packet_get_bignum2(g, &dlen); | |
340 | if ((dh = dh_new_group(g, p)) == NULL) | |
341 | fatal("dh_new_group"); | |
a306f2dd | 342 | |
343 | #ifdef DEBUG_KEXDH | |
94ec8c6b | 344 | fprintf(stderr, "\np= "); |
345 | BN_print_fp(stderr, dh->p); | |
346 | fprintf(stderr, "\ng= "); | |
347 | BN_print_fp(stderr, dh->g); | |
348 | fprintf(stderr, "\npub= "); | |
349 | BN_print_fp(stderr, dh->pub_key); | |
350 | fprintf(stderr, "\n"); | |
351 | DHparams_print_fp(stderr, dh); | |
352 | #endif | |
353 | ||
354 | debug("Sending SSH2_MSG_KEX_DH_GEX_INIT."); | |
355 | /* generate and send 'e', client DH public key */ | |
356 | packet_start(SSH2_MSG_KEX_DH_GEX_INIT); | |
357 | packet_put_bignum2(dh->pub_key); | |
a306f2dd | 358 | packet_send(); |
359 | packet_write_wait(); | |
94ec8c6b | 360 | |
361 | debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY."); | |
362 | ||
363 | packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY); | |
364 | ||
365 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
366 | ||
367 | /* key, cert */ | |
368 | server_host_key_blob = packet_get_string(&sbloblen); | |
369 | server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen); | |
370 | if (server_host_key == NULL) | |
371 | fatal("cannot decode server_host_key_blob"); | |
372 | ||
373 | check_host_key(host, hostaddr, server_host_key, | |
374 | options.user_hostfile2, options.system_hostfile2); | |
375 | ||
376 | /* DH paramter f, server public DH key */ | |
377 | dh_server_pub = BN_new(); | |
378 | if (dh_server_pub == NULL) | |
379 | fatal("dh_server_pub == NULL"); | |
380 | packet_get_bignum2(dh_server_pub, &dlen); | |
381 | ||
382 | #ifdef DEBUG_KEXDH | |
383 | fprintf(stderr, "\ndh_server_pub= "); | |
384 | BN_print_fp(stderr, dh_server_pub); | |
385 | fprintf(stderr, "\n"); | |
386 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
a306f2dd | 387 | #endif |
94ec8c6b | 388 | |
389 | /* signed H */ | |
390 | signature = packet_get_string(&slen); | |
391 | packet_done(); | |
392 | ||
393 | if (!dh_pub_is_valid(dh, dh_server_pub)) | |
394 | packet_disconnect("bad server public DH value"); | |
395 | ||
396 | klen = DH_size(dh); | |
397 | kbuf = xmalloc(klen); | |
398 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
399 | #ifdef DEBUG_KEXDH | |
400 | debug("shared secret: len %d/%d", klen, kout); | |
401 | fprintf(stderr, "shared secret == "); | |
402 | for (i = 0; i< kout; i++) | |
403 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
404 | fprintf(stderr, "\n"); | |
405 | #endif | |
406 | shared_secret = BN_new(); | |
407 | ||
408 | BN_bin2bn(kbuf, kout, shared_secret); | |
409 | memset(kbuf, 0, klen); | |
410 | xfree(kbuf); | |
411 | ||
412 | /* calc and verify H */ | |
413 | hash = kex_hash_gex( | |
414 | client_version_string, | |
415 | server_version_string, | |
416 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
417 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
418 | server_host_key_blob, sbloblen, | |
419 | nbits, dh->p, dh->g, | |
420 | dh->pub_key, | |
421 | dh_server_pub, | |
422 | shared_secret | |
423 | ); | |
424 | xfree(server_host_key_blob); | |
425 | DH_free(dh); | |
426 | #ifdef DEBUG_KEXDH | |
427 | fprintf(stderr, "hash == "); | |
428 | for (i = 0; i< 20; i++) | |
429 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
430 | fprintf(stderr, "\n"); | |
431 | #endif | |
432 | if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1) | |
433 | fatal("dsa_verify failed for server_host_key"); | |
434 | key_free(server_host_key); | |
435 | ||
436 | kex_derive_keys(kex, hash, shared_secret); | |
437 | packet_set_kex(kex); | |
438 | ||
439 | /* save session id */ | |
440 | session_id2_len = 20; | |
441 | session_id2 = xmalloc(session_id2_len); | |
442 | memcpy(session_id2, hash, session_id2_len); | |
a306f2dd | 443 | } |
71276795 | 444 | |
a306f2dd | 445 | /* |
446 | * Authenticate user | |
447 | */ | |
188adeb2 | 448 | |
449 | typedef struct Authctxt Authctxt; | |
450 | typedef struct Authmethod Authmethod; | |
451 | ||
452 | typedef int sign_cb_fn( | |
453 | Authctxt *authctxt, Key *key, | |
454 | unsigned char **sigp, int *lenp, unsigned char *data, int datalen); | |
455 | ||
456 | struct Authctxt { | |
457 | const char *server_user; | |
458 | const char *host; | |
459 | const char *service; | |
460 | AuthenticationConnection *agent; | |
188adeb2 | 461 | Authmethod *method; |
94ec8c6b | 462 | int success; |
188adeb2 | 463 | }; |
464 | struct Authmethod { | |
465 | char *name; /* string to compare against server's list */ | |
466 | int (*userauth)(Authctxt *authctxt); | |
467 | int *enabled; /* flag in option struct that enables method */ | |
468 | int *batch_flag; /* flag in option struct that disables method */ | |
469 | }; | |
470 | ||
471 | void input_userauth_success(int type, int plen, void *ctxt); | |
472 | void input_userauth_failure(int type, int plen, void *ctxt); | |
473 | void input_userauth_error(int type, int plen, void *ctxt); | |
94ec8c6b | 474 | void input_userauth_info_req(int type, int plen, void *ctxt); |
475 | ||
476 | int userauth_none(Authctxt *authctxt); | |
188adeb2 | 477 | int userauth_pubkey(Authctxt *authctxt); |
478 | int userauth_passwd(Authctxt *authctxt); | |
94ec8c6b | 479 | int userauth_kbdint(Authctxt *authctxt); |
188adeb2 | 480 | |
481 | void authmethod_clear(); | |
94ec8c6b | 482 | Authmethod *authmethod_get(char *authlist); |
483 | Authmethod *authmethod_lookup(const char *name); | |
188adeb2 | 484 | |
485 | Authmethod authmethods[] = { | |
486 | {"publickey", | |
487 | userauth_pubkey, | |
488 | &options.dsa_authentication, | |
489 | NULL}, | |
490 | {"password", | |
491 | userauth_passwd, | |
492 | &options.password_authentication, | |
493 | &options.batch_mode}, | |
94ec8c6b | 494 | {"keyboard-interactive", |
495 | userauth_kbdint, | |
496 | &options.kbd_interactive_authentication, | |
497 | &options.batch_mode}, | |
498 | {"none", | |
499 | userauth_none, | |
500 | NULL, | |
501 | NULL}, | |
188adeb2 | 502 | {NULL, NULL, NULL, NULL} |
503 | }; | |
504 | ||
505 | void | |
506 | ssh_userauth2(const char *server_user, char *host) | |
507 | { | |
508 | Authctxt authctxt; | |
509 | int type; | |
510 | int plen; | |
511 | ||
512 | debug("send SSH2_MSG_SERVICE_REQUEST"); | |
513 | packet_start(SSH2_MSG_SERVICE_REQUEST); | |
514 | packet_put_cstring("ssh-userauth"); | |
515 | packet_send(); | |
516 | packet_write_wait(); | |
517 | type = packet_read(&plen); | |
518 | if (type != SSH2_MSG_SERVICE_ACCEPT) { | |
519 | fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); | |
520 | } | |
521 | if (packet_remaining() > 0) { | |
522 | char *reply = packet_get_string(&plen); | |
523 | debug("service_accept: %s", reply); | |
524 | xfree(reply); | |
525 | packet_done(); | |
526 | } else { | |
527 | debug("buggy server: service_accept w/o service"); | |
528 | } | |
529 | packet_done(); | |
530 | debug("got SSH2_MSG_SERVICE_ACCEPT"); | |
531 | ||
532 | /* setup authentication context */ | |
533 | authctxt.agent = ssh_get_authentication_connection(); | |
534 | authctxt.server_user = server_user; | |
535 | authctxt.host = host; | |
536 | authctxt.service = "ssh-connection"; /* service name */ | |
537 | authctxt.success = 0; | |
94ec8c6b | 538 | authctxt.method = authmethod_lookup("none"); |
539 | if (authctxt.method == NULL) | |
540 | fatal("ssh_userauth2: internal error: cannot send userauth none request"); | |
541 | authmethod_clear(); | |
188adeb2 | 542 | |
543 | /* initial userauth request */ | |
94ec8c6b | 544 | userauth_none(&authctxt); |
188adeb2 | 545 | |
546 | dispatch_init(&input_userauth_error); | |
547 | dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); | |
548 | dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); | |
549 | dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ | |
550 | ||
551 | if (authctxt.agent != NULL) | |
552 | ssh_close_authentication_connection(authctxt.agent); | |
553 | ||
94ec8c6b | 554 | debug("ssh-userauth2 successfull: method %s", authctxt.method->name); |
188adeb2 | 555 | } |
556 | void | |
557 | input_userauth_error(int type, int plen, void *ctxt) | |
558 | { | |
559 | fatal("input_userauth_error: bad message during authentication"); | |
560 | } | |
561 | void | |
562 | input_userauth_success(int type, int plen, void *ctxt) | |
563 | { | |
564 | Authctxt *authctxt = ctxt; | |
565 | if (authctxt == NULL) | |
566 | fatal("input_userauth_success: no authentication context"); | |
567 | authctxt->success = 1; /* break out */ | |
568 | } | |
569 | void | |
570 | input_userauth_failure(int type, int plen, void *ctxt) | |
571 | { | |
572 | Authmethod *method = NULL; | |
573 | Authctxt *authctxt = ctxt; | |
574 | char *authlist = NULL; | |
575 | int partial; | |
188adeb2 | 576 | |
577 | if (authctxt == NULL) | |
578 | fatal("input_userauth_failure: no authentication context"); | |
579 | ||
94ec8c6b | 580 | authlist = packet_get_string(NULL); |
188adeb2 | 581 | partial = packet_get_char(); |
582 | packet_done(); | |
583 | ||
584 | if (partial != 0) | |
585 | debug("partial success"); | |
586 | debug("authentications that can continue: %s", authlist); | |
587 | ||
588 | for (;;) { | |
188adeb2 | 589 | method = authmethod_get(authlist); |
590 | if (method == NULL) | |
591 | fatal("Unable to find an authentication method"); | |
94ec8c6b | 592 | authctxt->method = method; |
188adeb2 | 593 | if (method->userauth(authctxt) != 0) { |
94ec8c6b | 594 | debug2("we sent a %s packet, wait for reply", method->name); |
188adeb2 | 595 | break; |
596 | } else { | |
597 | debug2("we did not send a packet, disable method"); | |
598 | method->enabled = NULL; | |
599 | } | |
600 | } | |
601 | xfree(authlist); | |
602 | } | |
603 | ||
94ec8c6b | 604 | int |
605 | userauth_none(Authctxt *authctxt) | |
606 | { | |
607 | /* initial userauth request */ | |
608 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
609 | packet_put_cstring(authctxt->server_user); | |
610 | packet_put_cstring(authctxt->service); | |
611 | packet_put_cstring(authctxt->method->name); | |
612 | packet_send(); | |
613 | packet_write_wait(); | |
614 | return 1; | |
615 | } | |
616 | ||
a306f2dd | 617 | int |
188adeb2 | 618 | userauth_passwd(Authctxt *authctxt) |
a306f2dd | 619 | { |
1d1ffb87 | 620 | static int attempt = 0; |
a306f2dd | 621 | char prompt[80]; |
622 | char *password; | |
623 | ||
fa649821 | 624 | if (attempt++ >= options.number_of_password_prompts) |
1d1ffb87 | 625 | return 0; |
626 | ||
fa649821 | 627 | if(attempt != 1) |
628 | error("Permission denied, please try again."); | |
629 | ||
a306f2dd | 630 | snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ", |
188adeb2 | 631 | authctxt->server_user, authctxt->host); |
a306f2dd | 632 | password = read_passphrase(prompt, 0); |
633 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
188adeb2 | 634 | packet_put_cstring(authctxt->server_user); |
635 | packet_put_cstring(authctxt->service); | |
94ec8c6b | 636 | packet_put_cstring(authctxt->method->name); |
a306f2dd | 637 | packet_put_char(0); |
638 | packet_put_cstring(password); | |
639 | memset(password, 0, strlen(password)); | |
640 | xfree(password); | |
641 | packet_send(); | |
642 | packet_write_wait(); | |
643 | return 1; | |
644 | } | |
645 | ||
2e73a022 | 646 | int |
188adeb2 | 647 | sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) |
a306f2dd | 648 | { |
649 | Buffer b; | |
a306f2dd | 650 | unsigned char *blob, *signature; |
651 | int bloblen, slen; | |
74fc9186 | 652 | int skip = 0; |
2e73a022 | 653 | int ret = -1; |
94ec8c6b | 654 | int have_sig = 1; |
a306f2dd | 655 | |
a306f2dd | 656 | dsa_make_key_blob(k, &blob, &bloblen); |
657 | ||
658 | /* data to be signed */ | |
659 | buffer_init(&b); | |
74fc9186 | 660 | if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) { |
661 | buffer_put_string(&b, session_id2, session_id2_len); | |
662 | skip = buffer_len(&b); | |
663 | } else { | |
664 | buffer_append(&b, session_id2, session_id2_len); | |
665 | skip = session_id2_len; | |
666 | } | |
a306f2dd | 667 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
188adeb2 | 668 | buffer_put_cstring(&b, authctxt->server_user); |
d0c832f3 | 669 | buffer_put_cstring(&b, |
670 | datafellows & SSH_BUG_PUBKEYAUTH ? | |
671 | "ssh-userauth" : | |
188adeb2 | 672 | authctxt->service); |
94ec8c6b | 673 | buffer_put_cstring(&b, authctxt->method->name); |
674 | buffer_put_char(&b, have_sig); | |
a306f2dd | 675 | buffer_put_cstring(&b, KEX_DSS); |
676 | buffer_put_string(&b, blob, bloblen); | |
a306f2dd | 677 | |
678 | /* generate signature */ | |
188adeb2 | 679 | ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); |
2e73a022 | 680 | if (ret == -1) { |
681 | xfree(blob); | |
682 | buffer_free(&b); | |
683 | return 0; | |
684 | } | |
a306f2dd | 685 | #ifdef DEBUG_DSS |
686 | buffer_dump(&b); | |
687 | #endif | |
d0c832f3 | 688 | if (datafellows & SSH_BUG_PUBKEYAUTH) { |
d0c832f3 | 689 | buffer_clear(&b); |
690 | buffer_append(&b, session_id2, session_id2_len); | |
691 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
188adeb2 | 692 | buffer_put_cstring(&b, authctxt->server_user); |
693 | buffer_put_cstring(&b, authctxt->service); | |
94ec8c6b | 694 | buffer_put_cstring(&b, authctxt->method->name); |
695 | buffer_put_char(&b, have_sig); | |
d0c832f3 | 696 | buffer_put_cstring(&b, KEX_DSS); |
697 | buffer_put_string(&b, blob, bloblen); | |
698 | } | |
699 | xfree(blob); | |
a306f2dd | 700 | /* append signature */ |
701 | buffer_put_string(&b, signature, slen); | |
702 | xfree(signature); | |
703 | ||
704 | /* skip session id and packet type */ | |
74fc9186 | 705 | if (buffer_len(&b) < skip + 1) |
188adeb2 | 706 | fatal("userauth_pubkey: internal error"); |
74fc9186 | 707 | buffer_consume(&b, skip + 1); |
a306f2dd | 708 | |
709 | /* put remaining data from buffer into packet */ | |
710 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
711 | packet_put_raw(buffer_ptr(&b), buffer_len(&b)); | |
712 | buffer_free(&b); | |
713 | ||
714 | /* send */ | |
715 | packet_send(); | |
716 | packet_write_wait(); | |
2e73a022 | 717 | |
718 | return 1; | |
4c8722d9 | 719 | } |
720 | ||
188adeb2 | 721 | /* sign callback */ |
722 | int dsa_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp, | |
723 | unsigned char *data, int datalen) | |
724 | { | |
725 | return dsa_sign(key, sigp, lenp, data, datalen); | |
726 | } | |
727 | ||
4c8722d9 | 728 | int |
188adeb2 | 729 | userauth_pubkey_identity(Authctxt *authctxt, char *filename) |
4c8722d9 | 730 | { |
731 | Key *k; | |
188adeb2 | 732 | int i, ret, try_next; |
4c8722d9 | 733 | struct stat st; |
734 | ||
735 | if (stat(filename, &st) != 0) { | |
736 | debug("key does not exist: %s", filename); | |
737 | return 0; | |
738 | } | |
739 | debug("try pubkey: %s", filename); | |
740 | ||
741 | k = key_new(KEY_DSA); | |
742 | if (!load_private_key(filename, "", k, NULL)) { | |
743 | int success = 0; | |
744 | char *passphrase; | |
745 | char prompt[300]; | |
746 | snprintf(prompt, sizeof prompt, | |
de273eef | 747 | "Enter passphrase for %s key '%.100s': ", |
748 | key_type(k), 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 | } | |
188adeb2 | 769 | ret = sign_and_send_pubkey(authctxt, k, dsa_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; | |
785 | char *comment; | |
786 | Key *k; | |
787 | int ret; | |
788 | ||
789 | if (called == 0) { | |
188adeb2 | 790 | k = ssh_get_first_identity(authctxt->agent, &comment, 2); |
791 | called = 1; | |
2e73a022 | 792 | } else { |
188adeb2 | 793 | k = ssh_get_next_identity(authctxt->agent, &comment, 2); |
2e73a022 | 794 | } |
188adeb2 | 795 | if (k == NULL) { |
796 | debug2("no more DSA keys from agent"); | |
2e73a022 | 797 | return 0; |
188adeb2 | 798 | } |
2e73a022 | 799 | debug("trying DSA agent key %s", comment); |
800 | xfree(comment); | |
188adeb2 | 801 | ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb); |
2e73a022 | 802 | key_free(k); |
803 | return ret; | |
a306f2dd | 804 | } |
805 | ||
188adeb2 | 806 | int |
807 | userauth_pubkey(Authctxt *authctxt) | |
a306f2dd | 808 | { |
188adeb2 | 809 | static int idx = 0; |
810 | int sent = 0; | |
811 | ||
812 | if (authctxt->agent != NULL) | |
813 | sent = userauth_pubkey_agent(authctxt); | |
814 | while (sent == 0 && idx < options.num_identity_files2) | |
815 | sent = userauth_pubkey_identity(authctxt, options.identity_files2[idx++]); | |
816 | return sent; | |
817 | } | |
a306f2dd | 818 | |
94ec8c6b | 819 | /* |
820 | * Send userauth request message specifying keyboard-interactive method. | |
821 | */ | |
822 | int | |
823 | userauth_kbdint(Authctxt *authctxt) | |
824 | { | |
825 | static int attempt = 0; | |
826 | ||
827 | if (attempt++ >= options.number_of_password_prompts) | |
828 | return 0; | |
829 | ||
830 | debug2("userauth_kbdint"); | |
831 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
832 | packet_put_cstring(authctxt->server_user); | |
833 | packet_put_cstring(authctxt->service); | |
834 | packet_put_cstring(authctxt->method->name); | |
835 | packet_put_cstring(""); /* lang */ | |
836 | packet_put_cstring(options.kbd_interactive_devices ? | |
837 | options.kbd_interactive_devices : ""); | |
838 | packet_send(); | |
839 | packet_write_wait(); | |
840 | ||
841 | dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); | |
842 | return 1; | |
843 | } | |
844 | ||
845 | /* | |
846 | * parse SSH2_MSG_USERAUTH_INFO_REQUEST, prompt user and send | |
847 | * SSH2_MSG_USERAUTH_INFO_RESPONSE | |
848 | */ | |
849 | void | |
850 | input_userauth_info_req(int type, int plen, void *ctxt) | |
851 | { | |
852 | Authctxt *authctxt = ctxt; | |
853 | char *name = NULL; | |
854 | char *inst = NULL; | |
855 | char *lang = NULL; | |
856 | char *prompt = NULL; | |
857 | char *response = NULL; | |
858 | unsigned int num_prompts, i; | |
859 | int echo = 0; | |
860 | ||
861 | debug2("input_userauth_info_req"); | |
862 | ||
863 | if (authctxt == NULL) | |
864 | fatal("input_userauth_info_req: no authentication context"); | |
865 | ||
866 | name = packet_get_string(NULL); | |
867 | inst = packet_get_string(NULL); | |
868 | lang = packet_get_string(NULL); | |
869 | ||
870 | if (strlen(name) > 0) | |
871 | cli_mesg(name); | |
872 | xfree(name); | |
873 | ||
874 | if (strlen(inst) > 0) | |
875 | cli_mesg(inst); | |
876 | xfree(inst); | |
877 | xfree(lang); /* unused */ | |
878 | ||
879 | num_prompts = packet_get_int(); | |
880 | /* | |
881 | * Begin to build info response packet based on prompts requested. | |
882 | * We commit to providing the correct number of responses, so if | |
883 | * further on we run into a problem that prevents this, we have to | |
884 | * be sure and clean this up and send a correct error response. | |
885 | */ | |
886 | packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); | |
887 | packet_put_int(num_prompts); | |
888 | ||
889 | for (i = 0; i < num_prompts; i++) { | |
890 | prompt = packet_get_string(NULL); | |
891 | echo = packet_get_char(); | |
892 | ||
893 | response = cli_prompt(prompt, echo); | |
894 | ||
895 | packet_put_cstring(response); | |
896 | memset(response, 0, strlen(response)); | |
897 | xfree(response); | |
898 | xfree(prompt); | |
899 | } | |
900 | packet_done(); /* done with parsing incoming message. */ | |
901 | ||
902 | packet_send(); | |
903 | packet_write_wait(); | |
904 | } | |
a306f2dd | 905 | |
188adeb2 | 906 | /* find auth method */ |
907 | ||
908 | #define DELIM "," | |
909 | ||
910 | static char *def_authlist = "publickey,password"; | |
911 | static char *authlist_current = NULL; /* clean copy used for comparison */ | |
912 | static char *authname_current = NULL; /* last used auth method */ | |
913 | static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */ | |
914 | static char *authlist_state = NULL; /* state variable for strtok_r() */ | |
915 | ||
916 | /* | |
917 | * Before starting to use a new authentication method list sent by the | |
918 | * server, reset internal variables. This should also be called when | |
919 | * finished processing server list to free resources. | |
920 | */ | |
921 | void | |
922 | authmethod_clear() | |
923 | { | |
924 | if (authlist_current != NULL) { | |
925 | xfree(authlist_current); | |
926 | authlist_current = NULL; | |
a306f2dd | 927 | } |
188adeb2 | 928 | if (authlist_working != NULL) { |
929 | xfree(authlist_working); | |
930 | authlist_working = NULL; | |
a306f2dd | 931 | } |
188adeb2 | 932 | if (authname_current != NULL) { |
933 | xfree(authname_current); | |
934 | authlist_state = NULL; | |
935 | } | |
936 | if (authlist_state != NULL) | |
937 | authlist_state = NULL; | |
938 | return; | |
939 | } | |
a306f2dd | 940 | |
188adeb2 | 941 | /* |
942 | * given auth method name, if configurable options permit this method fill | |
943 | * in auth_ident field and return true, otherwise return false. | |
944 | */ | |
945 | int | |
946 | authmethod_is_enabled(Authmethod *method) | |
947 | { | |
948 | if (method == NULL) | |
949 | return 0; | |
950 | /* return false if options indicate this method is disabled */ | |
951 | if (method->enabled == NULL || *method->enabled == 0) | |
952 | return 0; | |
953 | /* return false if batch mode is enabled but method needs interactive mode */ | |
954 | if (method->batch_flag != NULL && *method->batch_flag != 0) | |
955 | return 0; | |
956 | return 1; | |
957 | } | |
a306f2dd | 958 | |
188adeb2 | 959 | Authmethod * |
960 | authmethod_lookup(const char *name) | |
961 | { | |
962 | Authmethod *method = NULL; | |
963 | if (name != NULL) | |
964 | for (method = authmethods; method->name != NULL; method++) | |
965 | if (strcmp(name, method->name) == 0) | |
966 | return method; | |
967 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
968 | return NULL; | |
969 | } | |
970 | ||
971 | /* | |
972 | * Given the authentication method list sent by the server, return the | |
973 | * next method we should try. If the server initially sends a nil list, | |
974 | * use a built-in default list. If the server sends a nil list after | |
975 | * previously sending a valid list, continue using the list originally | |
976 | * sent. | |
977 | */ | |
978 | ||
979 | Authmethod * | |
980 | authmethod_get(char *authlist) | |
981 | { | |
982 | char *name = NULL; | |
983 | Authmethod *method = NULL; | |
984 | ||
985 | /* Use a suitable default if we're passed a nil list. */ | |
986 | if (authlist == NULL || strlen(authlist) == 0) | |
987 | authlist = def_authlist; | |
988 | ||
989 | if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) { | |
990 | /* start over if passed a different list */ | |
94ec8c6b | 991 | debug3("start over, passed a different list"); |
188adeb2 | 992 | authmethod_clear(); |
993 | authlist_current = xstrdup(authlist); | |
994 | authlist_working = xstrdup(authlist); | |
995 | name = strtok_r(authlist_working, DELIM, &authlist_state); | |
996 | } else { | |
997 | /* | |
998 | * try to use previously used authentication method | |
999 | * or continue to use previously passed list | |
1000 | */ | |
1001 | name = (authname_current != NULL) ? | |
1002 | authname_current : strtok_r(NULL, DELIM, &authlist_state); | |
1003 | } | |
1004 | ||
1005 | while (name != NULL) { | |
94ec8c6b | 1006 | debug3("authmethod_lookup %s", name); |
188adeb2 | 1007 | method = authmethod_lookup(name); |
94ec8c6b | 1008 | if (method != NULL && authmethod_is_enabled(method)) { |
1009 | debug3("authmethod_is_enabled %s", name); | |
a306f2dd | 1010 | break; |
94ec8c6b | 1011 | } |
188adeb2 | 1012 | name = strtok_r(NULL, DELIM, &authlist_state); |
94ec8c6b | 1013 | method = NULL; |
188adeb2 | 1014 | } |
1015 | ||
1016 | if (authname_current != NULL) | |
1017 | xfree(authname_current); | |
1018 | ||
94ec8c6b | 1019 | if (method != NULL) { |
188adeb2 | 1020 | debug("next auth method to try is %s", name); |
1021 | authname_current = xstrdup(name); | |
1022 | return method; | |
1023 | } else { | |
1024 | debug("no more auth methods to try"); | |
1025 | authname_current = NULL; | |
1026 | return NULL; | |
a306f2dd | 1027 | } |
a306f2dd | 1028 | } |