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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" | |
188adeb2 | 26 | RCSID("$OpenBSD: sshconnect2.c,v 1.20 2000/09/21 11:25:07 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" | |
40 | #include "cipher.h" | |
41 | #include "uidswap.h" | |
42 | #include "compat.h" | |
43 | #include "readconf.h" | |
44 | #include "bufaux.h" | |
45 | #include "ssh2.h" | |
46 | #include "kex.h" | |
47 | #include "myproposal.h" | |
48 | #include "key.h" | |
49 | #include "dsa.h" | |
50 | #include "sshconnect.h" | |
51 | #include "authfile.h" | |
188adeb2 | 52 | #include "dispatch.h" |
2e73a022 | 53 | #include "authfd.h" |
a306f2dd | 54 | |
55 | /* import */ | |
56 | extern char *client_version_string; | |
57 | extern char *server_version_string; | |
58 | extern Options options; | |
59 | ||
60 | /* | |
61 | * SSH2 key exchange | |
62 | */ | |
63 | ||
64 | unsigned char *session_id2 = NULL; | |
65 | int session_id2_len = 0; | |
66 | ||
67 | void | |
71276795 | 68 | ssh_kex_dh(Kex *kex, char *host, struct sockaddr *hostaddr, |
69 | Buffer *client_kexinit, Buffer *server_kexinit) | |
a306f2dd | 70 | { |
188adeb2 | 71 | #ifdef DEBUG_KEXDH |
72 | int i; | |
73 | #endif | |
71276795 | 74 | int plen, dlen; |
a306f2dd | 75 | unsigned int klen, kout; |
a306f2dd | 76 | char *signature = NULL; |
77 | unsigned int slen; | |
78 | char *server_host_key_blob = NULL; | |
79 | Key *server_host_key; | |
80 | unsigned int sbloblen; | |
81 | DH *dh; | |
82 | BIGNUM *dh_server_pub = 0; | |
83 | BIGNUM *shared_secret = 0; | |
a306f2dd | 84 | unsigned char *kbuf; |
85 | unsigned char *hash; | |
86 | ||
a306f2dd | 87 | debug("Sending SSH2_MSG_KEXDH_INIT."); |
a306f2dd | 88 | /* generate and send 'e', client DH public key */ |
89 | dh = dh_new_group1(); | |
90 | packet_start(SSH2_MSG_KEXDH_INIT); | |
91 | packet_put_bignum2(dh->pub_key); | |
92 | packet_send(); | |
93 | packet_write_wait(); | |
94 | ||
95 | #ifdef DEBUG_KEXDH | |
96 | fprintf(stderr, "\np= "); | |
188adeb2 | 97 | BN_print_fp(stderr, dh->p); |
a306f2dd | 98 | fprintf(stderr, "\ng= "); |
188adeb2 | 99 | BN_print_fp(stderr, dh->g); |
a306f2dd | 100 | fprintf(stderr, "\npub= "); |
188adeb2 | 101 | BN_print_fp(stderr, dh->pub_key); |
a306f2dd | 102 | fprintf(stderr, "\n"); |
103 | DHparams_print_fp(stderr, dh); | |
104 | #endif | |
105 | ||
106 | debug("Wait SSH2_MSG_KEXDH_REPLY."); | |
107 | ||
71276795 | 108 | packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY); |
a306f2dd | 109 | |
110 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
111 | ||
112 | /* key, cert */ | |
113 | server_host_key_blob = packet_get_string(&sbloblen); | |
114 | server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen); | |
115 | if (server_host_key == NULL) | |
116 | fatal("cannot decode server_host_key_blob"); | |
117 | ||
118 | check_host_key(host, hostaddr, server_host_key, | |
119 | options.user_hostfile2, options.system_hostfile2); | |
120 | ||
121 | /* DH paramter f, server public DH key */ | |
122 | dh_server_pub = BN_new(); | |
123 | if (dh_server_pub == NULL) | |
124 | fatal("dh_server_pub == NULL"); | |
125 | packet_get_bignum2(dh_server_pub, &dlen); | |
126 | ||
127 | #ifdef DEBUG_KEXDH | |
128 | fprintf(stderr, "\ndh_server_pub= "); | |
188adeb2 | 129 | BN_print_fp(stderr, dh_server_pub); |
a306f2dd | 130 | fprintf(stderr, "\n"); |
131 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
132 | #endif | |
133 | ||
134 | /* signed H */ | |
135 | signature = packet_get_string(&slen); | |
136 | packet_done(); | |
137 | ||
138 | if (!dh_pub_is_valid(dh, dh_server_pub)) | |
139 | packet_disconnect("bad server public DH value"); | |
140 | ||
141 | klen = DH_size(dh); | |
142 | kbuf = xmalloc(klen); | |
143 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
144 | #ifdef DEBUG_KEXDH | |
145 | debug("shared secret: len %d/%d", klen, kout); | |
146 | fprintf(stderr, "shared secret == "); | |
147 | for (i = 0; i< kout; i++) | |
148 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
149 | fprintf(stderr, "\n"); | |
150 | #endif | |
151 | shared_secret = BN_new(); | |
152 | ||
153 | BN_bin2bn(kbuf, kout, shared_secret); | |
154 | memset(kbuf, 0, klen); | |
155 | xfree(kbuf); | |
156 | ||
157 | /* calc and verify H */ | |
158 | hash = kex_hash( | |
159 | client_version_string, | |
160 | server_version_string, | |
161 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
162 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
163 | server_host_key_blob, sbloblen, | |
164 | dh->pub_key, | |
165 | dh_server_pub, | |
166 | shared_secret | |
167 | ); | |
168 | xfree(server_host_key_blob); | |
71276795 | 169 | DH_free(dh); |
a306f2dd | 170 | #ifdef DEBUG_KEXDH |
171 | fprintf(stderr, "hash == "); | |
172 | for (i = 0; i< 20; i++) | |
173 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
174 | fprintf(stderr, "\n"); | |
175 | #endif | |
176 | if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1) | |
177 | fatal("dsa_verify failed for server_host_key"); | |
178 | key_free(server_host_key); | |
179 | ||
180 | kex_derive_keys(kex, hash, shared_secret); | |
181 | packet_set_kex(kex); | |
182 | ||
a306f2dd | 183 | /* save session id */ |
184 | session_id2_len = 20; | |
185 | session_id2 = xmalloc(session_id2_len); | |
186 | memcpy(session_id2, hash, session_id2_len); | |
71276795 | 187 | } |
188 | ||
189 | void | |
190 | ssh_kex2(char *host, struct sockaddr *hostaddr) | |
191 | { | |
192 | int i, plen; | |
193 | Kex *kex; | |
194 | Buffer *client_kexinit, *server_kexinit; | |
195 | char *sprop[PROPOSAL_MAX]; | |
196 | ||
197 | if (options.ciphers != NULL) { | |
198 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
199 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
200 | } else if (options.cipher == SSH_CIPHER_3DES) { | |
201 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
202 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
203 | (char *) cipher_name(SSH_CIPHER_3DES_CBC); | |
204 | } else if (options.cipher == SSH_CIPHER_BLOWFISH) { | |
205 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
206 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
207 | (char *) cipher_name(SSH_CIPHER_BLOWFISH_CBC); | |
208 | } | |
209 | if (options.compression) { | |
210 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib"; | |
211 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; | |
212 | } else { | |
213 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none"; | |
214 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
215 | } | |
216 | ||
217 | /* buffers with raw kexinit messages */ | |
218 | server_kexinit = xmalloc(sizeof(*server_kexinit)); | |
219 | buffer_init(server_kexinit); | |
220 | client_kexinit = kex_init(myproposal); | |
221 | ||
222 | /* algorithm negotiation */ | |
223 | kex_exchange_kexinit(client_kexinit, server_kexinit, sprop); | |
224 | kex = kex_choose_conf(myproposal, sprop, 0); | |
225 | for (i = 0; i < PROPOSAL_MAX; i++) | |
226 | xfree(sprop[i]); | |
227 | ||
228 | /* server authentication and session key agreement */ | |
229 | ssh_kex_dh(kex, host, hostaddr, client_kexinit, server_kexinit); | |
230 | ||
231 | buffer_free(client_kexinit); | |
232 | buffer_free(server_kexinit); | |
233 | xfree(client_kexinit); | |
234 | xfree(server_kexinit); | |
a306f2dd | 235 | |
236 | debug("Wait SSH2_MSG_NEWKEYS."); | |
71276795 | 237 | packet_read_expect(&plen, SSH2_MSG_NEWKEYS); |
a306f2dd | 238 | packet_done(); |
239 | debug("GOT SSH2_MSG_NEWKEYS."); | |
240 | ||
241 | debug("send SSH2_MSG_NEWKEYS."); | |
242 | packet_start(SSH2_MSG_NEWKEYS); | |
243 | packet_send(); | |
244 | packet_write_wait(); | |
245 | debug("done: send SSH2_MSG_NEWKEYS."); | |
246 | ||
247 | #ifdef DEBUG_KEXDH | |
248 | /* send 1st encrypted/maced/compressed message */ | |
249 | packet_start(SSH2_MSG_IGNORE); | |
250 | packet_put_cstring("markus"); | |
251 | packet_send(); | |
252 | packet_write_wait(); | |
253 | #endif | |
254 | debug("done: KEX2."); | |
255 | } | |
71276795 | 256 | |
a306f2dd | 257 | /* |
258 | * Authenticate user | |
259 | */ | |
188adeb2 | 260 | |
261 | typedef struct Authctxt Authctxt; | |
262 | typedef struct Authmethod Authmethod; | |
263 | ||
264 | typedef int sign_cb_fn( | |
265 | Authctxt *authctxt, Key *key, | |
266 | unsigned char **sigp, int *lenp, unsigned char *data, int datalen); | |
267 | ||
268 | struct Authctxt { | |
269 | const char *server_user; | |
270 | const char *host; | |
271 | const char *service; | |
272 | AuthenticationConnection *agent; | |
273 | int success; | |
274 | Authmethod *method; | |
275 | }; | |
276 | struct Authmethod { | |
277 | char *name; /* string to compare against server's list */ | |
278 | int (*userauth)(Authctxt *authctxt); | |
279 | int *enabled; /* flag in option struct that enables method */ | |
280 | int *batch_flag; /* flag in option struct that disables method */ | |
281 | }; | |
282 | ||
283 | void input_userauth_success(int type, int plen, void *ctxt); | |
284 | void input_userauth_failure(int type, int plen, void *ctxt); | |
285 | void input_userauth_error(int type, int plen, void *ctxt); | |
286 | int userauth_pubkey(Authctxt *authctxt); | |
287 | int userauth_passwd(Authctxt *authctxt); | |
288 | ||
289 | void authmethod_clear(); | |
290 | Authmethod *authmethod_get(char *auth_list); | |
291 | ||
292 | Authmethod authmethods[] = { | |
293 | {"publickey", | |
294 | userauth_pubkey, | |
295 | &options.dsa_authentication, | |
296 | NULL}, | |
297 | {"password", | |
298 | userauth_passwd, | |
299 | &options.password_authentication, | |
300 | &options.batch_mode}, | |
301 | {NULL, NULL, NULL, NULL} | |
302 | }; | |
303 | ||
304 | void | |
305 | ssh_userauth2(const char *server_user, char *host) | |
306 | { | |
307 | Authctxt authctxt; | |
308 | int type; | |
309 | int plen; | |
310 | ||
311 | debug("send SSH2_MSG_SERVICE_REQUEST"); | |
312 | packet_start(SSH2_MSG_SERVICE_REQUEST); | |
313 | packet_put_cstring("ssh-userauth"); | |
314 | packet_send(); | |
315 | packet_write_wait(); | |
316 | type = packet_read(&plen); | |
317 | if (type != SSH2_MSG_SERVICE_ACCEPT) { | |
318 | fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); | |
319 | } | |
320 | if (packet_remaining() > 0) { | |
321 | char *reply = packet_get_string(&plen); | |
322 | debug("service_accept: %s", reply); | |
323 | xfree(reply); | |
324 | packet_done(); | |
325 | } else { | |
326 | debug("buggy server: service_accept w/o service"); | |
327 | } | |
328 | packet_done(); | |
329 | debug("got SSH2_MSG_SERVICE_ACCEPT"); | |
330 | ||
331 | /* setup authentication context */ | |
332 | authctxt.agent = ssh_get_authentication_connection(); | |
333 | authctxt.server_user = server_user; | |
334 | authctxt.host = host; | |
335 | authctxt.service = "ssh-connection"; /* service name */ | |
336 | authctxt.success = 0; | |
337 | authctxt.method = NULL; | |
338 | ||
339 | /* initial userauth request */ | |
340 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
341 | packet_put_cstring(authctxt.server_user); | |
342 | packet_put_cstring(authctxt.service); | |
343 | packet_put_cstring("none"); | |
344 | packet_send(); | |
345 | packet_write_wait(); | |
346 | ||
347 | authmethod_clear(); | |
348 | ||
349 | dispatch_init(&input_userauth_error); | |
350 | dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); | |
351 | dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); | |
352 | dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ | |
353 | ||
354 | if (authctxt.agent != NULL) | |
355 | ssh_close_authentication_connection(authctxt.agent); | |
356 | ||
357 | debug("ssh-userauth2 successfull"); | |
358 | } | |
359 | void | |
360 | input_userauth_error(int type, int plen, void *ctxt) | |
361 | { | |
362 | fatal("input_userauth_error: bad message during authentication"); | |
363 | } | |
364 | void | |
365 | input_userauth_success(int type, int plen, void *ctxt) | |
366 | { | |
367 | Authctxt *authctxt = ctxt; | |
368 | if (authctxt == NULL) | |
369 | fatal("input_userauth_success: no authentication context"); | |
370 | authctxt->success = 1; /* break out */ | |
371 | } | |
372 | void | |
373 | input_userauth_failure(int type, int plen, void *ctxt) | |
374 | { | |
375 | Authmethod *method = NULL; | |
376 | Authctxt *authctxt = ctxt; | |
377 | char *authlist = NULL; | |
378 | int partial; | |
379 | int dlen; | |
380 | ||
381 | if (authctxt == NULL) | |
382 | fatal("input_userauth_failure: no authentication context"); | |
383 | ||
384 | authlist = packet_get_string(&dlen); | |
385 | partial = packet_get_char(); | |
386 | packet_done(); | |
387 | ||
388 | if (partial != 0) | |
389 | debug("partial success"); | |
390 | debug("authentications that can continue: %s", authlist); | |
391 | ||
392 | for (;;) { | |
393 | /* try old method or get next method */ | |
394 | method = authmethod_get(authlist); | |
395 | if (method == NULL) | |
396 | fatal("Unable to find an authentication method"); | |
397 | if (method->userauth(authctxt) != 0) { | |
398 | debug2("we sent a packet, wait for reply"); | |
399 | break; | |
400 | } else { | |
401 | debug2("we did not send a packet, disable method"); | |
402 | method->enabled = NULL; | |
403 | } | |
404 | } | |
405 | xfree(authlist); | |
406 | } | |
407 | ||
a306f2dd | 408 | int |
188adeb2 | 409 | userauth_passwd(Authctxt *authctxt) |
a306f2dd | 410 | { |
1d1ffb87 | 411 | static int attempt = 0; |
a306f2dd | 412 | char prompt[80]; |
413 | char *password; | |
414 | ||
fa649821 | 415 | if (attempt++ >= options.number_of_password_prompts) |
1d1ffb87 | 416 | return 0; |
417 | ||
fa649821 | 418 | if(attempt != 1) |
419 | error("Permission denied, please try again."); | |
420 | ||
a306f2dd | 421 | snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ", |
188adeb2 | 422 | authctxt->server_user, authctxt->host); |
a306f2dd | 423 | password = read_passphrase(prompt, 0); |
424 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
188adeb2 | 425 | packet_put_cstring(authctxt->server_user); |
426 | packet_put_cstring(authctxt->service); | |
a306f2dd | 427 | packet_put_cstring("password"); |
428 | packet_put_char(0); | |
429 | packet_put_cstring(password); | |
430 | memset(password, 0, strlen(password)); | |
431 | xfree(password); | |
432 | packet_send(); | |
433 | packet_write_wait(); | |
434 | return 1; | |
435 | } | |
436 | ||
2e73a022 | 437 | int |
188adeb2 | 438 | sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) |
a306f2dd | 439 | { |
440 | Buffer b; | |
a306f2dd | 441 | unsigned char *blob, *signature; |
442 | int bloblen, slen; | |
74fc9186 | 443 | int skip = 0; |
2e73a022 | 444 | int ret = -1; |
a306f2dd | 445 | |
a306f2dd | 446 | dsa_make_key_blob(k, &blob, &bloblen); |
447 | ||
448 | /* data to be signed */ | |
449 | buffer_init(&b); | |
74fc9186 | 450 | if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) { |
451 | buffer_put_string(&b, session_id2, session_id2_len); | |
452 | skip = buffer_len(&b); | |
453 | } else { | |
454 | buffer_append(&b, session_id2, session_id2_len); | |
455 | skip = session_id2_len; | |
456 | } | |
a306f2dd | 457 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
188adeb2 | 458 | buffer_put_cstring(&b, authctxt->server_user); |
d0c832f3 | 459 | buffer_put_cstring(&b, |
460 | datafellows & SSH_BUG_PUBKEYAUTH ? | |
461 | "ssh-userauth" : | |
188adeb2 | 462 | authctxt->service); |
a306f2dd | 463 | buffer_put_cstring(&b, "publickey"); |
464 | buffer_put_char(&b, 1); | |
465 | buffer_put_cstring(&b, KEX_DSS); | |
466 | buffer_put_string(&b, blob, bloblen); | |
a306f2dd | 467 | |
468 | /* generate signature */ | |
188adeb2 | 469 | ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); |
2e73a022 | 470 | if (ret == -1) { |
471 | xfree(blob); | |
472 | buffer_free(&b); | |
473 | return 0; | |
474 | } | |
a306f2dd | 475 | #ifdef DEBUG_DSS |
476 | buffer_dump(&b); | |
477 | #endif | |
d0c832f3 | 478 | if (datafellows & SSH_BUG_PUBKEYAUTH) { |
d0c832f3 | 479 | buffer_clear(&b); |
480 | buffer_append(&b, session_id2, session_id2_len); | |
481 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
188adeb2 | 482 | buffer_put_cstring(&b, authctxt->server_user); |
483 | buffer_put_cstring(&b, authctxt->service); | |
d0c832f3 | 484 | buffer_put_cstring(&b, "publickey"); |
485 | buffer_put_char(&b, 1); | |
486 | buffer_put_cstring(&b, KEX_DSS); | |
487 | buffer_put_string(&b, blob, bloblen); | |
488 | } | |
489 | xfree(blob); | |
a306f2dd | 490 | /* append signature */ |
491 | buffer_put_string(&b, signature, slen); | |
492 | xfree(signature); | |
493 | ||
494 | /* skip session id and packet type */ | |
74fc9186 | 495 | if (buffer_len(&b) < skip + 1) |
188adeb2 | 496 | fatal("userauth_pubkey: internal error"); |
74fc9186 | 497 | buffer_consume(&b, skip + 1); |
a306f2dd | 498 | |
499 | /* put remaining data from buffer into packet */ | |
500 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
501 | packet_put_raw(buffer_ptr(&b), buffer_len(&b)); | |
502 | buffer_free(&b); | |
503 | ||
504 | /* send */ | |
505 | packet_send(); | |
506 | packet_write_wait(); | |
2e73a022 | 507 | |
508 | return 1; | |
4c8722d9 | 509 | } |
510 | ||
188adeb2 | 511 | /* sign callback */ |
512 | int dsa_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp, | |
513 | unsigned char *data, int datalen) | |
514 | { | |
515 | return dsa_sign(key, sigp, lenp, data, datalen); | |
516 | } | |
517 | ||
4c8722d9 | 518 | int |
188adeb2 | 519 | userauth_pubkey_identity(Authctxt *authctxt, char *filename) |
4c8722d9 | 520 | { |
521 | Key *k; | |
188adeb2 | 522 | int i, ret, try_next; |
4c8722d9 | 523 | struct stat st; |
524 | ||
525 | if (stat(filename, &st) != 0) { | |
526 | debug("key does not exist: %s", filename); | |
527 | return 0; | |
528 | } | |
529 | debug("try pubkey: %s", filename); | |
530 | ||
531 | k = key_new(KEY_DSA); | |
532 | if (!load_private_key(filename, "", k, NULL)) { | |
533 | int success = 0; | |
534 | char *passphrase; | |
535 | char prompt[300]; | |
536 | snprintf(prompt, sizeof prompt, | |
537 | "Enter passphrase for DSA key '%.100s': ", | |
538 | filename); | |
188adeb2 | 539 | for (i = 0; i < options.number_of_password_prompts; i++) { |
540 | passphrase = read_passphrase(prompt, 0); | |
541 | if (strcmp(passphrase, "") != 0) { | |
542 | success = load_private_key(filename, passphrase, k, NULL); | |
543 | try_next = 0; | |
544 | } else { | |
545 | debug2("no passphrase given, try next key"); | |
546 | try_next = 1; | |
547 | } | |
548 | memset(passphrase, 0, strlen(passphrase)); | |
549 | xfree(passphrase); | |
550 | if (success || try_next) | |
551 | break; | |
552 | debug2("bad passphrase given, try again..."); | |
553 | } | |
4c8722d9 | 554 | if (!success) { |
555 | key_free(k); | |
556 | return 0; | |
557 | } | |
558 | } | |
188adeb2 | 559 | ret = sign_and_send_pubkey(authctxt, k, dsa_sign_cb); |
2e73a022 | 560 | key_free(k); |
561 | return ret; | |
562 | } | |
563 | ||
188adeb2 | 564 | /* sign callback */ |
565 | int agent_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp, | |
2e73a022 | 566 | unsigned char *data, int datalen) |
567 | { | |
188adeb2 | 568 | return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); |
2e73a022 | 569 | } |
570 | ||
571 | int | |
188adeb2 | 572 | userauth_pubkey_agent(Authctxt *authctxt) |
2e73a022 | 573 | { |
574 | static int called = 0; | |
575 | char *comment; | |
576 | Key *k; | |
577 | int ret; | |
578 | ||
579 | if (called == 0) { | |
188adeb2 | 580 | k = ssh_get_first_identity(authctxt->agent, &comment, 2); |
581 | called = 1; | |
2e73a022 | 582 | } else { |
188adeb2 | 583 | k = ssh_get_next_identity(authctxt->agent, &comment, 2); |
2e73a022 | 584 | } |
188adeb2 | 585 | if (k == NULL) { |
586 | debug2("no more DSA keys from agent"); | |
2e73a022 | 587 | return 0; |
188adeb2 | 588 | } |
2e73a022 | 589 | debug("trying DSA agent key %s", comment); |
590 | xfree(comment); | |
188adeb2 | 591 | ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb); |
2e73a022 | 592 | key_free(k); |
593 | return ret; | |
a306f2dd | 594 | } |
595 | ||
188adeb2 | 596 | int |
597 | userauth_pubkey(Authctxt *authctxt) | |
a306f2dd | 598 | { |
188adeb2 | 599 | static int idx = 0; |
600 | int sent = 0; | |
601 | ||
602 | if (authctxt->agent != NULL) | |
603 | sent = userauth_pubkey_agent(authctxt); | |
604 | while (sent == 0 && idx < options.num_identity_files2) | |
605 | sent = userauth_pubkey_identity(authctxt, options.identity_files2[idx++]); | |
606 | return sent; | |
607 | } | |
a306f2dd | 608 | |
a306f2dd | 609 | |
188adeb2 | 610 | /* find auth method */ |
611 | ||
612 | #define DELIM "," | |
613 | ||
614 | static char *def_authlist = "publickey,password"; | |
615 | static char *authlist_current = NULL; /* clean copy used for comparison */ | |
616 | static char *authname_current = NULL; /* last used auth method */ | |
617 | static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */ | |
618 | static char *authlist_state = NULL; /* state variable for strtok_r() */ | |
619 | ||
620 | /* | |
621 | * Before starting to use a new authentication method list sent by the | |
622 | * server, reset internal variables. This should also be called when | |
623 | * finished processing server list to free resources. | |
624 | */ | |
625 | void | |
626 | authmethod_clear() | |
627 | { | |
628 | if (authlist_current != NULL) { | |
629 | xfree(authlist_current); | |
630 | authlist_current = NULL; | |
a306f2dd | 631 | } |
188adeb2 | 632 | if (authlist_working != NULL) { |
633 | xfree(authlist_working); | |
634 | authlist_working = NULL; | |
a306f2dd | 635 | } |
188adeb2 | 636 | if (authname_current != NULL) { |
637 | xfree(authname_current); | |
638 | authlist_state = NULL; | |
639 | } | |
640 | if (authlist_state != NULL) | |
641 | authlist_state = NULL; | |
642 | return; | |
643 | } | |
a306f2dd | 644 | |
188adeb2 | 645 | /* |
646 | * given auth method name, if configurable options permit this method fill | |
647 | * in auth_ident field and return true, otherwise return false. | |
648 | */ | |
649 | int | |
650 | authmethod_is_enabled(Authmethod *method) | |
651 | { | |
652 | if (method == NULL) | |
653 | return 0; | |
654 | /* return false if options indicate this method is disabled */ | |
655 | if (method->enabled == NULL || *method->enabled == 0) | |
656 | return 0; | |
657 | /* return false if batch mode is enabled but method needs interactive mode */ | |
658 | if (method->batch_flag != NULL && *method->batch_flag != 0) | |
659 | return 0; | |
660 | return 1; | |
661 | } | |
a306f2dd | 662 | |
188adeb2 | 663 | Authmethod * |
664 | authmethod_lookup(const char *name) | |
665 | { | |
666 | Authmethod *method = NULL; | |
667 | if (name != NULL) | |
668 | for (method = authmethods; method->name != NULL; method++) | |
669 | if (strcmp(name, method->name) == 0) | |
670 | return method; | |
671 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
672 | return NULL; | |
673 | } | |
674 | ||
675 | /* | |
676 | * Given the authentication method list sent by the server, return the | |
677 | * next method we should try. If the server initially sends a nil list, | |
678 | * use a built-in default list. If the server sends a nil list after | |
679 | * previously sending a valid list, continue using the list originally | |
680 | * sent. | |
681 | */ | |
682 | ||
683 | Authmethod * | |
684 | authmethod_get(char *authlist) | |
685 | { | |
686 | char *name = NULL; | |
687 | Authmethod *method = NULL; | |
688 | ||
689 | /* Use a suitable default if we're passed a nil list. */ | |
690 | if (authlist == NULL || strlen(authlist) == 0) | |
691 | authlist = def_authlist; | |
692 | ||
693 | if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) { | |
694 | /* start over if passed a different list */ | |
695 | authmethod_clear(); | |
696 | authlist_current = xstrdup(authlist); | |
697 | authlist_working = xstrdup(authlist); | |
698 | name = strtok_r(authlist_working, DELIM, &authlist_state); | |
699 | } else { | |
700 | /* | |
701 | * try to use previously used authentication method | |
702 | * or continue to use previously passed list | |
703 | */ | |
704 | name = (authname_current != NULL) ? | |
705 | authname_current : strtok_r(NULL, DELIM, &authlist_state); | |
706 | } | |
707 | ||
708 | while (name != NULL) { | |
709 | method = authmethod_lookup(name); | |
710 | if (method != NULL && authmethod_is_enabled(method)) | |
a306f2dd | 711 | break; |
188adeb2 | 712 | name = strtok_r(NULL, DELIM, &authlist_state); |
713 | } | |
714 | ||
715 | if (authname_current != NULL) | |
716 | xfree(authname_current); | |
717 | ||
718 | if (name != NULL) { | |
719 | debug("next auth method to try is %s", name); | |
720 | authname_current = xstrdup(name); | |
721 | return method; | |
722 | } else { | |
723 | debug("no more auth methods to try"); | |
724 | authname_current = NULL; | |
725 | return NULL; | |
a306f2dd | 726 | } |
a306f2dd | 727 | } |