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a306f2dd | 1 | /* |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
a306f2dd | 5 | * Code to connect to a remote host, and to perform the client side of the |
6 | * login (authentication) dialog. | |
7 | * | |
bcbf86ec | 8 | * As far as I am concerned, the code I have written for this software |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
a306f2dd | 13 | */ |
14 | ||
15 | #include "includes.h" | |
fee56204 | 16 | RCSID("$OpenBSD: sshconnect1.c,v 1.28 2001/03/08 21:42:33 markus Exp $"); |
a306f2dd | 17 | |
18 | #include <openssl/bn.h> | |
a306f2dd | 19 | #include <openssl/evp.h> |
20 | ||
42f11eb2 | 21 | #ifdef KRB4 |
22 | #include <krb.h> | |
42f11eb2 | 23 | #endif |
24 | #ifdef AFS | |
25 | #include <kafs.h> | |
53a24016 | 26 | #include "radix.h" |
42f11eb2 | 27 | #endif |
28 | ||
29 | #include "ssh.h" | |
30 | #include "ssh1.h" | |
a306f2dd | 31 | #include "xmalloc.h" |
32 | #include "rsa.h" | |
a306f2dd | 33 | #include "buffer.h" |
34 | #include "packet.h" | |
a306f2dd | 35 | #include "mpaux.h" |
36 | #include "uidswap.h" | |
42f11eb2 | 37 | #include "log.h" |
a306f2dd | 38 | #include "readconf.h" |
39 | #include "key.h" | |
4c8722d9 | 40 | #include "authfd.h" |
a306f2dd | 41 | #include "sshconnect.h" |
42 | #include "authfile.h" | |
42f11eb2 | 43 | #include "readpass.h" |
44 | #include "cipher.h" | |
45 | #include "canohost.h" | |
a306f2dd | 46 | |
47 | /* Session id for the current session. */ | |
1e3b8b07 | 48 | u_char session_id[16]; |
49 | u_int supported_authentications = 0; | |
a306f2dd | 50 | |
51 | extern Options options; | |
52 | extern char *__progname; | |
53 | ||
54 | /* | |
55 | * Checks if the user has an authentication agent, and if so, tries to | |
56 | * authenticate using the agent. | |
57 | */ | |
58 | int | |
5ca51e19 | 59 | try_agent_authentication(void) |
a306f2dd | 60 | { |
2e73a022 | 61 | int type; |
a306f2dd | 62 | char *comment; |
63 | AuthenticationConnection *auth; | |
1e3b8b07 | 64 | u_char response[16]; |
65 | u_int i; | |
2e73a022 | 66 | int plen, clen; |
67 | Key *key; | |
68 | BIGNUM *challenge; | |
a306f2dd | 69 | |
70 | /* Get connection to the agent. */ | |
71 | auth = ssh_get_authentication_connection(); | |
72 | if (!auth) | |
73 | return 0; | |
74 | ||
a306f2dd | 75 | challenge = BN_new(); |
76 | ||
77 | /* Loop through identities served by the agent. */ | |
2e73a022 | 78 | for (key = ssh_get_first_identity(auth, &comment, 1); |
79 | key != NULL; | |
80 | key = ssh_get_next_identity(auth, &comment, 1)) { | |
a306f2dd | 81 | |
82 | /* Try this identity. */ | |
83 | debug("Trying RSA authentication via agent with '%.100s'", comment); | |
84 | xfree(comment); | |
85 | ||
86 | /* Tell the server that we are willing to authenticate using this key. */ | |
87 | packet_start(SSH_CMSG_AUTH_RSA); | |
2e73a022 | 88 | packet_put_bignum(key->rsa->n); |
a306f2dd | 89 | packet_send(); |
90 | packet_write_wait(); | |
91 | ||
92 | /* Wait for server's response. */ | |
93 | type = packet_read(&plen); | |
94 | ||
95 | /* The server sends failure if it doesn\'t like our key or | |
96 | does not support RSA authentication. */ | |
97 | if (type == SSH_SMSG_FAILURE) { | |
98 | debug("Server refused our key."); | |
2e73a022 | 99 | key_free(key); |
a306f2dd | 100 | continue; |
101 | } | |
102 | /* Otherwise it should have sent a challenge. */ | |
103 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
104 | packet_disconnect("Protocol error during RSA authentication: %d", | |
105 | type); | |
106 | ||
107 | packet_get_bignum(challenge, &clen); | |
108 | ||
109 | packet_integrity_check(plen, clen, type); | |
110 | ||
111 | debug("Received RSA challenge from server."); | |
112 | ||
113 | /* Ask the agent to decrypt the challenge. */ | |
2e73a022 | 114 | if (!ssh_decrypt_challenge(auth, key, challenge, session_id, 1, response)) { |
115 | /* | |
116 | * The agent failed to authenticate this identifier | |
117 | * although it advertised it supports this. Just | |
118 | * return a wrong value. | |
119 | */ | |
a306f2dd | 120 | log("Authentication agent failed to decrypt challenge."); |
121 | memset(response, 0, sizeof(response)); | |
122 | } | |
2e73a022 | 123 | key_free(key); |
a306f2dd | 124 | debug("Sending response to RSA challenge."); |
125 | ||
126 | /* Send the decrypted challenge back to the server. */ | |
127 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
128 | for (i = 0; i < 16; i++) | |
129 | packet_put_char(response[i]); | |
130 | packet_send(); | |
131 | packet_write_wait(); | |
132 | ||
133 | /* Wait for response from the server. */ | |
134 | type = packet_read(&plen); | |
135 | ||
136 | /* The server returns success if it accepted the authentication. */ | |
137 | if (type == SSH_SMSG_SUCCESS) { | |
eea39c02 | 138 | ssh_close_authentication_connection(auth); |
a306f2dd | 139 | BN_clear_free(challenge); |
2e73a022 | 140 | debug("RSA authentication accepted by server."); |
a306f2dd | 141 | return 1; |
142 | } | |
143 | /* Otherwise it should return failure. */ | |
144 | if (type != SSH_SMSG_FAILURE) | |
145 | packet_disconnect("Protocol error waiting RSA auth response: %d", | |
146 | type); | |
147 | } | |
eea39c02 | 148 | ssh_close_authentication_connection(auth); |
a306f2dd | 149 | BN_clear_free(challenge); |
a306f2dd | 150 | debug("RSA authentication using agent refused."); |
151 | return 0; | |
152 | } | |
153 | ||
154 | /* | |
155 | * Computes the proper response to a RSA challenge, and sends the response to | |
156 | * the server. | |
157 | */ | |
158 | void | |
159 | respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv) | |
160 | { | |
1e3b8b07 | 161 | u_char buf[32], response[16]; |
a306f2dd | 162 | MD5_CTX md; |
163 | int i, len; | |
164 | ||
165 | /* Decrypt the challenge using the private key. */ | |
46aa2d1f | 166 | /* XXX think about Bleichenbacher, too */ |
167 | if (rsa_private_decrypt(challenge, challenge, prv) <= 0) | |
168 | packet_disconnect( | |
169 | "respond_to_rsa_challenge: rsa_private_decrypt failed"); | |
a306f2dd | 170 | |
171 | /* Compute the response. */ | |
172 | /* The response is MD5 of decrypted challenge plus session id. */ | |
173 | len = BN_num_bytes(challenge); | |
174 | if (len <= 0 || len > sizeof(buf)) | |
46aa2d1f | 175 | packet_disconnect( |
176 | "respond_to_rsa_challenge: bad challenge length %d", len); | |
a306f2dd | 177 | |
178 | memset(buf, 0, sizeof(buf)); | |
179 | BN_bn2bin(challenge, buf + sizeof(buf) - len); | |
180 | MD5_Init(&md); | |
181 | MD5_Update(&md, buf, 32); | |
182 | MD5_Update(&md, session_id, 16); | |
183 | MD5_Final(response, &md); | |
184 | ||
185 | debug("Sending response to host key RSA challenge."); | |
186 | ||
187 | /* Send the response back to the server. */ | |
188 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
189 | for (i = 0; i < 16; i++) | |
190 | packet_put_char(response[i]); | |
191 | packet_send(); | |
192 | packet_write_wait(); | |
193 | ||
194 | memset(buf, 0, sizeof(buf)); | |
195 | memset(response, 0, sizeof(response)); | |
196 | memset(&md, 0, sizeof(md)); | |
197 | } | |
198 | ||
199 | /* | |
200 | * Checks if the user has authentication file, and if so, tries to authenticate | |
201 | * the user using it. | |
202 | */ | |
203 | int | |
204 | try_rsa_authentication(const char *authfile) | |
205 | { | |
206 | BIGNUM *challenge; | |
207 | Key *public; | |
208 | Key *private; | |
209 | char *passphrase, *comment; | |
210 | int type, i; | |
211 | int plen, clen; | |
212 | ||
213 | /* Try to load identification for the authentication key. */ | |
fa08c86b | 214 | public = key_new(KEY_RSA1); |
a306f2dd | 215 | if (!load_public_key(authfile, public, &comment)) { |
216 | key_free(public); | |
217 | /* Could not load it. Fail. */ | |
218 | return 0; | |
219 | } | |
220 | debug("Trying RSA authentication with key '%.100s'", comment); | |
221 | ||
222 | /* Tell the server that we are willing to authenticate using this key. */ | |
223 | packet_start(SSH_CMSG_AUTH_RSA); | |
224 | packet_put_bignum(public->rsa->n); | |
225 | packet_send(); | |
226 | packet_write_wait(); | |
227 | ||
228 | /* We no longer need the public key. */ | |
229 | key_free(public); | |
230 | ||
231 | /* Wait for server's response. */ | |
232 | type = packet_read(&plen); | |
233 | ||
234 | /* | |
235 | * The server responds with failure if it doesn\'t like our key or | |
236 | * doesn\'t support RSA authentication. | |
237 | */ | |
238 | if (type == SSH_SMSG_FAILURE) { | |
239 | debug("Server refused our key."); | |
240 | xfree(comment); | |
241 | return 0; | |
242 | } | |
243 | /* Otherwise, the server should respond with a challenge. */ | |
244 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
245 | packet_disconnect("Protocol error during RSA authentication: %d", type); | |
246 | ||
247 | /* Get the challenge from the packet. */ | |
248 | challenge = BN_new(); | |
249 | packet_get_bignum(challenge, &clen); | |
250 | ||
251 | packet_integrity_check(plen, clen, type); | |
252 | ||
253 | debug("Received RSA challenge from server."); | |
254 | ||
fa08c86b | 255 | private = key_new(KEY_RSA1); |
a306f2dd | 256 | /* |
257 | * Load the private key. Try first with empty passphrase; if it | |
258 | * fails, ask for a passphrase. | |
259 | */ | |
260 | if (!load_private_key(authfile, "", private, NULL)) { | |
261 | char buf[300]; | |
262 | snprintf(buf, sizeof buf, "Enter passphrase for RSA key '%.100s': ", | |
263 | comment); | |
264 | if (!options.batch_mode) | |
265 | passphrase = read_passphrase(buf, 0); | |
266 | else { | |
267 | debug("Will not query passphrase for %.100s in batch mode.", | |
268 | comment); | |
269 | passphrase = xstrdup(""); | |
270 | } | |
271 | ||
272 | /* Load the authentication file using the pasphrase. */ | |
273 | if (!load_private_key(authfile, passphrase, private, NULL)) { | |
274 | memset(passphrase, 0, strlen(passphrase)); | |
275 | xfree(passphrase); | |
276 | error("Bad passphrase."); | |
277 | ||
278 | /* Send a dummy response packet to avoid protocol error. */ | |
279 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
280 | for (i = 0; i < 16; i++) | |
281 | packet_put_char(0); | |
282 | packet_send(); | |
283 | packet_write_wait(); | |
284 | ||
285 | /* Expect the server to reject it... */ | |
286 | packet_read_expect(&plen, SSH_SMSG_FAILURE); | |
287 | xfree(comment); | |
eea39c02 | 288 | key_free(private); |
289 | BN_clear_free(challenge); | |
a306f2dd | 290 | return 0; |
291 | } | |
292 | /* Destroy the passphrase. */ | |
293 | memset(passphrase, 0, strlen(passphrase)); | |
294 | xfree(passphrase); | |
295 | } | |
296 | /* We no longer need the comment. */ | |
297 | xfree(comment); | |
298 | ||
299 | /* Compute and send a response to the challenge. */ | |
300 | respond_to_rsa_challenge(challenge, private->rsa); | |
301 | ||
302 | /* Destroy the private key. */ | |
303 | key_free(private); | |
304 | ||
305 | /* We no longer need the challenge. */ | |
306 | BN_clear_free(challenge); | |
307 | ||
308 | /* Wait for response from the server. */ | |
309 | type = packet_read(&plen); | |
310 | if (type == SSH_SMSG_SUCCESS) { | |
311 | debug("RSA authentication accepted by server."); | |
312 | return 1; | |
313 | } | |
314 | if (type != SSH_SMSG_FAILURE) | |
315 | packet_disconnect("Protocol error waiting RSA auth response: %d", type); | |
316 | debug("RSA authentication refused."); | |
317 | return 0; | |
318 | } | |
319 | ||
320 | /* | |
321 | * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv | |
322 | * authentication and RSA host authentication. | |
323 | */ | |
324 | int | |
325 | try_rhosts_rsa_authentication(const char *local_user, RSA * host_key) | |
326 | { | |
327 | int type; | |
328 | BIGNUM *challenge; | |
329 | int plen, clen; | |
330 | ||
331 | debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication."); | |
332 | ||
333 | /* Tell the server that we are willing to authenticate using this key. */ | |
334 | packet_start(SSH_CMSG_AUTH_RHOSTS_RSA); | |
335 | packet_put_string(local_user, strlen(local_user)); | |
336 | packet_put_int(BN_num_bits(host_key->n)); | |
337 | packet_put_bignum(host_key->e); | |
338 | packet_put_bignum(host_key->n); | |
339 | packet_send(); | |
340 | packet_write_wait(); | |
341 | ||
342 | /* Wait for server's response. */ | |
343 | type = packet_read(&plen); | |
344 | ||
345 | /* The server responds with failure if it doesn't admit our | |
346 | .rhosts authentication or doesn't know our host key. */ | |
347 | if (type == SSH_SMSG_FAILURE) { | |
348 | debug("Server refused our rhosts authentication or host key."); | |
349 | return 0; | |
350 | } | |
351 | /* Otherwise, the server should respond with a challenge. */ | |
352 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
353 | packet_disconnect("Protocol error during RSA authentication: %d", type); | |
354 | ||
355 | /* Get the challenge from the packet. */ | |
356 | challenge = BN_new(); | |
357 | packet_get_bignum(challenge, &clen); | |
358 | ||
359 | packet_integrity_check(plen, clen, type); | |
360 | ||
361 | debug("Received RSA challenge for host key from server."); | |
362 | ||
363 | /* Compute a response to the challenge. */ | |
364 | respond_to_rsa_challenge(challenge, host_key); | |
365 | ||
366 | /* We no longer need the challenge. */ | |
367 | BN_clear_free(challenge); | |
368 | ||
369 | /* Wait for response from the server. */ | |
370 | type = packet_read(&plen); | |
371 | if (type == SSH_SMSG_SUCCESS) { | |
372 | debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server."); | |
373 | return 1; | |
374 | } | |
375 | if (type != SSH_SMSG_FAILURE) | |
376 | packet_disconnect("Protocol error waiting RSA auth response: %d", type); | |
377 | debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused."); | |
378 | return 0; | |
379 | } | |
380 | ||
381 | #ifdef KRB4 | |
382 | int | |
5ca51e19 | 383 | try_kerberos_authentication(void) |
a306f2dd | 384 | { |
385 | KTEXT_ST auth; /* Kerberos data */ | |
386 | char *reply; | |
387 | char inst[INST_SZ]; | |
388 | char *realm; | |
389 | CREDENTIALS cred; | |
390 | int r, type, plen; | |
391 | socklen_t slen; | |
392 | Key_schedule schedule; | |
393 | u_long checksum, cksum; | |
394 | MSG_DAT msg_data; | |
395 | struct sockaddr_in local, foreign; | |
396 | struct stat st; | |
397 | ||
398 | /* Don't do anything if we don't have any tickets. */ | |
399 | if (stat(tkt_string(), &st) < 0) | |
400 | return 0; | |
401 | ||
61e96248 | 402 | strncpy(inst, (char *) krb_get_phost(get_canonical_hostname(1)), INST_SZ); |
a306f2dd | 403 | |
61e96248 | 404 | realm = (char *) krb_realmofhost(get_canonical_hostname(1)); |
a306f2dd | 405 | if (!realm) { |
61e96248 | 406 | debug("Kerberos V4: no realm for %s", get_canonical_hostname(1)); |
a306f2dd | 407 | return 0; |
408 | } | |
409 | /* This can really be anything. */ | |
410 | checksum = (u_long) getpid(); | |
411 | ||
412 | r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum); | |
413 | if (r != KSUCCESS) { | |
414 | debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]); | |
415 | return 0; | |
416 | } | |
417 | /* Get session key to decrypt the server's reply with. */ | |
418 | r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred); | |
419 | if (r != KSUCCESS) { | |
420 | debug("get_cred failed: %s", krb_err_txt[r]); | |
421 | return 0; | |
422 | } | |
423 | des_key_sched((des_cblock *) cred.session, schedule); | |
424 | ||
425 | /* Send authentication info to server. */ | |
426 | packet_start(SSH_CMSG_AUTH_KERBEROS); | |
427 | packet_put_string((char *) auth.dat, auth.length); | |
428 | packet_send(); | |
429 | packet_write_wait(); | |
430 | ||
431 | /* Zero the buffer. */ | |
432 | (void) memset(auth.dat, 0, MAX_KTXT_LEN); | |
433 | ||
434 | slen = sizeof(local); | |
435 | memset(&local, 0, sizeof(local)); | |
436 | if (getsockname(packet_get_connection_in(), | |
437 | (struct sockaddr *) & local, &slen) < 0) | |
438 | debug("getsockname failed: %s", strerror(errno)); | |
439 | ||
440 | slen = sizeof(foreign); | |
441 | memset(&foreign, 0, sizeof(foreign)); | |
442 | if (getpeername(packet_get_connection_in(), | |
443 | (struct sockaddr *) & foreign, &slen) < 0) { | |
444 | debug("getpeername failed: %s", strerror(errno)); | |
445 | fatal_cleanup(); | |
446 | } | |
447 | /* Get server reply. */ | |
448 | type = packet_read(&plen); | |
449 | switch (type) { | |
450 | case SSH_SMSG_FAILURE: | |
451 | /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */ | |
452 | debug("Kerberos V4 authentication failed."); | |
453 | return 0; | |
454 | break; | |
455 | ||
456 | case SSH_SMSG_AUTH_KERBEROS_RESPONSE: | |
457 | /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */ | |
458 | debug("Kerberos V4 authentication accepted."); | |
459 | ||
460 | /* Get server's response. */ | |
1e3b8b07 | 461 | reply = packet_get_string((u_int *) &auth.length); |
a306f2dd | 462 | memcpy(auth.dat, reply, auth.length); |
463 | xfree(reply); | |
464 | ||
465 | packet_integrity_check(plen, 4 + auth.length, type); | |
466 | ||
467 | /* | |
468 | * If his response isn't properly encrypted with the session | |
469 | * key, and the decrypted checksum fails to match, he's | |
470 | * bogus. Bail out. | |
471 | */ | |
472 | r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session, | |
473 | &foreign, &local, &msg_data); | |
474 | if (r != KSUCCESS) { | |
475 | debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]); | |
476 | packet_disconnect("Kerberos V4 challenge failed!"); | |
477 | } | |
478 | /* Fetch the (incremented) checksum that we supplied in the request. */ | |
479 | (void) memcpy((char *) &cksum, (char *) msg_data.app_data, sizeof(cksum)); | |
480 | cksum = ntohl(cksum); | |
481 | ||
482 | /* If it matches, we're golden. */ | |
483 | if (cksum == checksum + 1) { | |
484 | debug("Kerberos V4 challenge successful."); | |
485 | return 1; | |
486 | } else | |
487 | packet_disconnect("Kerberos V4 challenge failed!"); | |
488 | break; | |
489 | ||
490 | default: | |
491 | packet_disconnect("Protocol error on Kerberos V4 response: %d", type); | |
492 | } | |
493 | return 0; | |
494 | } | |
495 | ||
496 | #endif /* KRB4 */ | |
497 | ||
498 | #ifdef AFS | |
499 | int | |
5ca51e19 | 500 | send_kerberos_tgt(void) |
a306f2dd | 501 | { |
502 | CREDENTIALS *creds; | |
503 | char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ]; | |
504 | int r, type, plen; | |
505 | char buffer[8192]; | |
506 | struct stat st; | |
507 | ||
508 | /* Don't do anything if we don't have any tickets. */ | |
509 | if (stat(tkt_string(), &st) < 0) | |
510 | return 0; | |
511 | ||
512 | creds = xmalloc(sizeof(*creds)); | |
513 | ||
514 | if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) { | |
515 | debug("Kerberos V4 tf_fullname failed: %s", krb_err_txt[r]); | |
516 | return 0; | |
517 | } | |
518 | if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) { | |
519 | debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]); | |
520 | return 0; | |
521 | } | |
522 | if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) { | |
523 | debug("Kerberos V4 ticket expired: %s", TKT_FILE); | |
524 | return 0; | |
525 | } | |
1e3b8b07 | 526 | creds_to_radix(creds, (u_char *)buffer, sizeof buffer); |
a306f2dd | 527 | xfree(creds); |
528 | ||
529 | packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); | |
530 | packet_put_string(buffer, strlen(buffer)); | |
531 | packet_send(); | |
532 | packet_write_wait(); | |
533 | ||
534 | type = packet_read(&plen); | |
535 | ||
536 | if (type == SSH_SMSG_FAILURE) | |
537 | debug("Kerberos TGT for realm %s rejected.", prealm); | |
538 | else if (type != SSH_SMSG_SUCCESS) | |
539 | packet_disconnect("Protocol error on Kerberos TGT response: %d", type); | |
540 | ||
541 | return 1; | |
542 | } | |
543 | ||
544 | void | |
545 | send_afs_tokens(void) | |
546 | { | |
547 | CREDENTIALS creds; | |
548 | struct ViceIoctl parms; | |
549 | struct ClearToken ct; | |
550 | int i, type, len, plen; | |
551 | char buf[2048], *p, *server_cell; | |
552 | char buffer[8192]; | |
553 | ||
554 | /* Move over ktc_GetToken, here's something leaner. */ | |
555 | for (i = 0; i < 100; i++) { /* just in case */ | |
556 | parms.in = (char *) &i; | |
557 | parms.in_size = sizeof(i); | |
558 | parms.out = buf; | |
559 | parms.out_size = sizeof(buf); | |
560 | if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) | |
561 | break; | |
562 | p = buf; | |
563 | ||
564 | /* Get secret token. */ | |
1e3b8b07 | 565 | memcpy(&creds.ticket_st.length, p, sizeof(u_int)); |
a306f2dd | 566 | if (creds.ticket_st.length > MAX_KTXT_LEN) |
567 | break; | |
1e3b8b07 | 568 | p += sizeof(u_int); |
a306f2dd | 569 | memcpy(creds.ticket_st.dat, p, creds.ticket_st.length); |
570 | p += creds.ticket_st.length; | |
571 | ||
572 | /* Get clear token. */ | |
573 | memcpy(&len, p, sizeof(len)); | |
574 | if (len != sizeof(struct ClearToken)) | |
575 | break; | |
576 | p += sizeof(len); | |
577 | memcpy(&ct, p, len); | |
578 | p += len; | |
579 | p += sizeof(len); /* primary flag */ | |
580 | server_cell = p; | |
581 | ||
582 | /* Flesh out our credentials. */ | |
583 | strlcpy(creds.service, "afs", sizeof creds.service); | |
584 | creds.instance[0] = '\0'; | |
585 | strlcpy(creds.realm, server_cell, REALM_SZ); | |
586 | memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ); | |
587 | creds.issue_date = ct.BeginTimestamp; | |
588 | creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp); | |
589 | creds.kvno = ct.AuthHandle; | |
590 | snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId); | |
591 | creds.pinst[0] = '\0'; | |
592 | ||
593 | /* Encode token, ship it off. */ | |
b5c334cc | 594 | if (creds_to_radix(&creds, (u_char *) buffer, sizeof buffer) <= 0) |
a306f2dd | 595 | break; |
596 | packet_start(SSH_CMSG_HAVE_AFS_TOKEN); | |
597 | packet_put_string(buffer, strlen(buffer)); | |
598 | packet_send(); | |
599 | packet_write_wait(); | |
600 | ||
601 | /* Roger, Roger. Clearance, Clarence. What's your vector, | |
602 | Victor? */ | |
603 | type = packet_read(&plen); | |
604 | ||
605 | if (type == SSH_SMSG_FAILURE) | |
606 | debug("AFS token for cell %s rejected.", server_cell); | |
607 | else if (type != SSH_SMSG_SUCCESS) | |
608 | packet_disconnect("Protocol error on AFS token response: %d", type); | |
609 | } | |
610 | } | |
611 | ||
612 | #endif /* AFS */ | |
613 | ||
614 | /* | |
615 | * Tries to authenticate with any string-based challenge/response system. | |
616 | * Note that the client code is not tied to s/key or TIS. | |
617 | */ | |
618 | int | |
5ca51e19 | 619 | try_challenge_reponse_authentication(void) |
a306f2dd | 620 | { |
621 | int type, i; | |
622 | int payload_len; | |
1e3b8b07 | 623 | u_int clen; |
e3a70753 | 624 | char prompt[1024]; |
a306f2dd | 625 | char *challenge, *response; |
626 | ||
d464095c | 627 | debug("Doing challenge reponse authentication."); |
a306f2dd | 628 | |
a306f2dd | 629 | for (i = 0; i < options.number_of_password_prompts; i++) { |
e3a70753 | 630 | /* request a challenge */ |
631 | packet_start(SSH_CMSG_AUTH_TIS); | |
632 | packet_send(); | |
633 | packet_write_wait(); | |
634 | ||
635 | type = packet_read(&payload_len); | |
636 | if (type != SSH_SMSG_FAILURE && | |
637 | type != SSH_SMSG_AUTH_TIS_CHALLENGE) { | |
638 | packet_disconnect("Protocol error: got %d in response " | |
d464095c | 639 | "to SSH_CMSG_AUTH_TIS", type); |
e3a70753 | 640 | } |
641 | if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) { | |
d464095c | 642 | debug("No challenge."); |
e3a70753 | 643 | return 0; |
644 | } | |
645 | challenge = packet_get_string(&clen); | |
646 | packet_integrity_check(payload_len, (4 + clen), type); | |
59c97189 | 647 | snprintf(prompt, sizeof prompt, "%s%s", challenge, |
648 | strchr(challenge, '\n') ? "" : "\nResponse: "); | |
e3a70753 | 649 | xfree(challenge); |
a306f2dd | 650 | if (i != 0) |
651 | error("Permission denied, please try again."); | |
e3a70753 | 652 | if (options.cipher == SSH_CIPHER_NONE) |
653 | log("WARNING: Encryption is disabled! " | |
654 | "Reponse will be transmitted in clear text."); | |
655 | response = read_passphrase(prompt, 0); | |
656 | if (strcmp(response, "") == 0) { | |
657 | xfree(response); | |
658 | break; | |
659 | } | |
a306f2dd | 660 | packet_start(SSH_CMSG_AUTH_TIS_RESPONSE); |
0ae4fe1d | 661 | ssh_put_password(response); |
a306f2dd | 662 | memset(response, 0, strlen(response)); |
663 | xfree(response); | |
664 | packet_send(); | |
665 | packet_write_wait(); | |
666 | type = packet_read(&payload_len); | |
667 | if (type == SSH_SMSG_SUCCESS) | |
668 | return 1; | |
669 | if (type != SSH_SMSG_FAILURE) | |
670 | packet_disconnect("Protocol error: got %d in response " | |
d464095c | 671 | "to SSH_CMSG_AUTH_TIS_RESPONSE", type); |
a306f2dd | 672 | } |
673 | /* failure */ | |
674 | return 0; | |
675 | } | |
676 | ||
677 | /* | |
678 | * Tries to authenticate with plain passwd authentication. | |
679 | */ | |
680 | int | |
681 | try_password_authentication(char *prompt) | |
682 | { | |
683 | int type, i, payload_len; | |
684 | char *password; | |
685 | ||
686 | debug("Doing password authentication."); | |
687 | if (options.cipher == SSH_CIPHER_NONE) | |
688 | log("WARNING: Encryption is disabled! Password will be transmitted in clear text."); | |
689 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
690 | if (i != 0) | |
691 | error("Permission denied, please try again."); | |
692 | password = read_passphrase(prompt, 0); | |
693 | packet_start(SSH_CMSG_AUTH_PASSWORD); | |
0ae4fe1d | 694 | ssh_put_password(password); |
a306f2dd | 695 | memset(password, 0, strlen(password)); |
696 | xfree(password); | |
697 | packet_send(); | |
698 | packet_write_wait(); | |
699 | ||
700 | type = packet_read(&payload_len); | |
701 | if (type == SSH_SMSG_SUCCESS) | |
702 | return 1; | |
703 | if (type != SSH_SMSG_FAILURE) | |
704 | packet_disconnect("Protocol error: got %d in response to passwd auth", type); | |
705 | } | |
706 | /* failure */ | |
707 | return 0; | |
708 | } | |
709 | ||
710 | /* | |
711 | * SSH1 key exchange | |
712 | */ | |
713 | void | |
714 | ssh_kex(char *host, struct sockaddr *hostaddr) | |
715 | { | |
716 | int i; | |
717 | BIGNUM *key; | |
718 | RSA *host_key; | |
719 | RSA *public_key; | |
720 | Key k; | |
721 | int bits, rbits; | |
722 | int ssh_cipher_default = SSH_CIPHER_3DES; | |
1e3b8b07 | 723 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
724 | u_char cookie[8]; | |
725 | u_int supported_ciphers; | |
726 | u_int server_flags, client_flags; | |
a306f2dd | 727 | int payload_len, clen, sum_len = 0; |
728 | u_int32_t rand = 0; | |
729 | ||
730 | debug("Waiting for server public key."); | |
731 | ||
732 | /* Wait for a public key packet from the server. */ | |
733 | packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY); | |
734 | ||
735 | /* Get cookie from the packet. */ | |
736 | for (i = 0; i < 8; i++) | |
737 | cookie[i] = packet_get_char(); | |
738 | ||
739 | /* Get the public key. */ | |
740 | public_key = RSA_new(); | |
741 | bits = packet_get_int();/* bits */ | |
742 | public_key->e = BN_new(); | |
743 | packet_get_bignum(public_key->e, &clen); | |
744 | sum_len += clen; | |
745 | public_key->n = BN_new(); | |
746 | packet_get_bignum(public_key->n, &clen); | |
747 | sum_len += clen; | |
748 | ||
749 | rbits = BN_num_bits(public_key->n); | |
750 | if (bits != rbits) { | |
751 | log("Warning: Server lies about size of server public key: " | |
752 | "actual size is %d bits vs. announced %d.", rbits, bits); | |
753 | log("Warning: This may be due to an old implementation of ssh."); | |
754 | } | |
755 | /* Get the host key. */ | |
756 | host_key = RSA_new(); | |
757 | bits = packet_get_int();/* bits */ | |
758 | host_key->e = BN_new(); | |
759 | packet_get_bignum(host_key->e, &clen); | |
760 | sum_len += clen; | |
761 | host_key->n = BN_new(); | |
762 | packet_get_bignum(host_key->n, &clen); | |
763 | sum_len += clen; | |
764 | ||
765 | rbits = BN_num_bits(host_key->n); | |
766 | if (bits != rbits) { | |
767 | log("Warning: Server lies about size of server host key: " | |
768 | "actual size is %d bits vs. announced %d.", rbits, bits); | |
769 | log("Warning: This may be due to an old implementation of ssh."); | |
770 | } | |
771 | ||
772 | /* Get protocol flags. */ | |
773 | server_flags = packet_get_int(); | |
774 | packet_set_protocol_flags(server_flags); | |
775 | ||
776 | supported_ciphers = packet_get_int(); | |
777 | supported_authentications = packet_get_int(); | |
778 | ||
779 | debug("Received server public key (%d bits) and host key (%d bits).", | |
780 | BN_num_bits(public_key->n), BN_num_bits(host_key->n)); | |
781 | ||
782 | packet_integrity_check(payload_len, | |
783 | 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4, | |
784 | SSH_SMSG_PUBLIC_KEY); | |
fa08c86b | 785 | k.type = KEY_RSA1; |
a306f2dd | 786 | k.rsa = host_key; |
787 | check_host_key(host, hostaddr, &k, | |
788 | options.user_hostfile, options.system_hostfile); | |
789 | ||
790 | client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN; | |
791 | ||
792 | compute_session_id(session_id, cookie, host_key->n, public_key->n); | |
793 | ||
794 | /* Generate a session key. */ | |
795 | arc4random_stir(); | |
796 | ||
797 | /* | |
798 | * Generate an encryption key for the session. The key is a 256 bit | |
799 | * random number, interpreted as a 32-byte key, with the least | |
800 | * significant 8 bits being the first byte of the key. | |
801 | */ | |
802 | for (i = 0; i < 32; i++) { | |
803 | if (i % 4 == 0) | |
804 | rand = arc4random(); | |
805 | session_key[i] = rand & 0xff; | |
806 | rand >>= 8; | |
807 | } | |
808 | ||
809 | /* | |
810 | * According to the protocol spec, the first byte of the session key | |
811 | * is the highest byte of the integer. The session key is xored with | |
812 | * the first 16 bytes of the session id. | |
813 | */ | |
814 | key = BN_new(); | |
815 | BN_set_word(key, 0); | |
816 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
817 | BN_lshift(key, key, 8); | |
818 | if (i < 16) | |
819 | BN_add_word(key, session_key[i] ^ session_id[i]); | |
820 | else | |
821 | BN_add_word(key, session_key[i]); | |
822 | } | |
823 | ||
824 | /* | |
825 | * Encrypt the integer using the public key and host key of the | |
826 | * server (key with smaller modulus first). | |
827 | */ | |
828 | if (BN_cmp(public_key->n, host_key->n) < 0) { | |
829 | /* Public key has smaller modulus. */ | |
830 | if (BN_num_bits(host_key->n) < | |
831 | BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) { | |
832 | fatal("respond_to_rsa_challenge: host_key %d < public_key %d + " | |
833 | "SSH_KEY_BITS_RESERVED %d", | |
834 | BN_num_bits(host_key->n), | |
835 | BN_num_bits(public_key->n), | |
836 | SSH_KEY_BITS_RESERVED); | |
837 | } | |
838 | rsa_public_encrypt(key, key, public_key); | |
839 | rsa_public_encrypt(key, key, host_key); | |
840 | } else { | |
841 | /* Host key has smaller modulus (or they are equal). */ | |
842 | if (BN_num_bits(public_key->n) < | |
843 | BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) { | |
844 | fatal("respond_to_rsa_challenge: public_key %d < host_key %d + " | |
845 | "SSH_KEY_BITS_RESERVED %d", | |
846 | BN_num_bits(public_key->n), | |
847 | BN_num_bits(host_key->n), | |
848 | SSH_KEY_BITS_RESERVED); | |
849 | } | |
850 | rsa_public_encrypt(key, key, host_key); | |
851 | rsa_public_encrypt(key, key, public_key); | |
852 | } | |
853 | ||
854 | /* Destroy the public keys since we no longer need them. */ | |
855 | RSA_free(public_key); | |
856 | RSA_free(host_key); | |
857 | ||
c523303b | 858 | if (options.cipher == SSH_CIPHER_NOT_SET) { |
859 | if (cipher_mask_ssh1(1) & supported_ciphers & (1 << ssh_cipher_default)) | |
860 | options.cipher = ssh_cipher_default; | |
861 | } else if (options.cipher == SSH_CIPHER_ILLEGAL || | |
862 | !(cipher_mask_ssh1(1) & (1 << options.cipher))) { | |
d0c832f3 | 863 | log("No valid SSH1 cipher, using %.100s instead.", |
94ec8c6b | 864 | cipher_name(ssh_cipher_default)); |
865 | options.cipher = ssh_cipher_default; | |
a306f2dd | 866 | } |
867 | /* Check that the selected cipher is supported. */ | |
868 | if (!(supported_ciphers & (1 << options.cipher))) | |
869 | fatal("Selected cipher type %.100s not supported by server.", | |
870 | cipher_name(options.cipher)); | |
871 | ||
872 | debug("Encryption type: %.100s", cipher_name(options.cipher)); | |
873 | ||
874 | /* Send the encrypted session key to the server. */ | |
875 | packet_start(SSH_CMSG_SESSION_KEY); | |
876 | packet_put_char(options.cipher); | |
877 | ||
878 | /* Send the cookie back to the server. */ | |
879 | for (i = 0; i < 8; i++) | |
880 | packet_put_char(cookie[i]); | |
881 | ||
882 | /* Send and destroy the encrypted encryption key integer. */ | |
883 | packet_put_bignum(key); | |
884 | BN_clear_free(key); | |
885 | ||
886 | /* Send protocol flags. */ | |
887 | packet_put_int(client_flags); | |
888 | ||
889 | /* Send the packet now. */ | |
890 | packet_send(); | |
891 | packet_write_wait(); | |
892 | ||
893 | debug("Sent encrypted session key."); | |
894 | ||
895 | /* Set the encryption key. */ | |
896 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher); | |
897 | ||
898 | /* We will no longer need the session key here. Destroy any extra copies. */ | |
899 | memset(session_key, 0, sizeof(session_key)); | |
900 | ||
901 | /* | |
902 | * Expect a success message from the server. Note that this message | |
903 | * will be received in encrypted form. | |
904 | */ | |
905 | packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); | |
906 | ||
907 | debug("Received encrypted confirmation."); | |
908 | } | |
909 | ||
910 | /* | |
911 | * Authenticate user | |
912 | */ | |
913 | void | |
914 | ssh_userauth( | |
b5c334cc | 915 | const char *local_user, |
916 | const char *server_user, | |
a306f2dd | 917 | char *host, |
918 | int host_key_valid, RSA *own_host_key) | |
919 | { | |
920 | int i, type; | |
921 | int payload_len; | |
922 | ||
923 | if (supported_authentications == 0) | |
924 | fatal("ssh_userauth: server supports no auth methods"); | |
925 | ||
926 | /* Send the name of the user to log in as on the server. */ | |
927 | packet_start(SSH_CMSG_USER); | |
928 | packet_put_string(server_user, strlen(server_user)); | |
929 | packet_send(); | |
930 | packet_write_wait(); | |
931 | ||
932 | /* | |
933 | * The server should respond with success if no authentication is | |
934 | * needed (the user has no password). Otherwise the server responds | |
935 | * with failure. | |
936 | */ | |
937 | type = packet_read(&payload_len); | |
938 | ||
939 | /* check whether the connection was accepted without authentication. */ | |
940 | if (type == SSH_SMSG_SUCCESS) | |
941 | return; | |
942 | if (type != SSH_SMSG_FAILURE) | |
943 | packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", | |
944 | type); | |
945 | ||
946 | #ifdef AFS | |
947 | /* Try Kerberos tgt passing if the server supports it. */ | |
948 | if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) && | |
949 | options.kerberos_tgt_passing) { | |
950 | if (options.cipher == SSH_CIPHER_NONE) | |
951 | log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!"); | |
952 | (void) send_kerberos_tgt(); | |
953 | } | |
954 | /* Try AFS token passing if the server supports it. */ | |
955 | if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) && | |
956 | options.afs_token_passing && k_hasafs()) { | |
957 | if (options.cipher == SSH_CIPHER_NONE) | |
958 | log("WARNING: Encryption is disabled! Token will be transmitted in the clear!"); | |
959 | send_afs_tokens(); | |
960 | } | |
961 | #endif /* AFS */ | |
962 | ||
963 | #ifdef KRB4 | |
964 | if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) && | |
965 | options.kerberos_authentication) { | |
966 | debug("Trying Kerberos authentication."); | |
967 | if (try_kerberos_authentication()) { | |
968 | /* The server should respond with success or failure. */ | |
969 | type = packet_read(&payload_len); | |
970 | if (type == SSH_SMSG_SUCCESS) | |
971 | return; | |
972 | if (type != SSH_SMSG_FAILURE) | |
973 | packet_disconnect("Protocol error: got %d in response to Kerberos auth", type); | |
974 | } | |
975 | } | |
976 | #endif /* KRB4 */ | |
977 | ||
978 | /* | |
979 | * Use rhosts authentication if running in privileged socket and we | |
980 | * do not wish to remain anonymous. | |
981 | */ | |
982 | if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) && | |
983 | options.rhosts_authentication) { | |
984 | debug("Trying rhosts authentication."); | |
985 | packet_start(SSH_CMSG_AUTH_RHOSTS); | |
986 | packet_put_string(local_user, strlen(local_user)); | |
987 | packet_send(); | |
988 | packet_write_wait(); | |
989 | ||
990 | /* The server should respond with success or failure. */ | |
991 | type = packet_read(&payload_len); | |
992 | if (type == SSH_SMSG_SUCCESS) | |
993 | return; | |
994 | if (type != SSH_SMSG_FAILURE) | |
995 | packet_disconnect("Protocol error: got %d in response to rhosts auth", | |
996 | type); | |
997 | } | |
998 | /* | |
999 | * Try .rhosts or /etc/hosts.equiv authentication with RSA host | |
1000 | * authentication. | |
1001 | */ | |
1002 | if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) && | |
1003 | options.rhosts_rsa_authentication && host_key_valid) { | |
1004 | if (try_rhosts_rsa_authentication(local_user, own_host_key)) | |
1005 | return; | |
1006 | } | |
1007 | /* Try RSA authentication if the server supports it. */ | |
1008 | if ((supported_authentications & (1 << SSH_AUTH_RSA)) && | |
1009 | options.rsa_authentication) { | |
1010 | /* | |
1011 | * Try RSA authentication using the authentication agent. The | |
1012 | * agent is tried first because no passphrase is needed for | |
1013 | * it, whereas identity files may require passphrases. | |
1014 | */ | |
1015 | if (try_agent_authentication()) | |
1016 | return; | |
1017 | ||
1018 | /* Try RSA authentication for each identity. */ | |
1019 | for (i = 0; i < options.num_identity_files; i++) | |
fee56204 | 1020 | if (options.identity_keys[i] != NULL && |
1021 | options.identity_keys[i]->type == KEY_RSA1 && | |
fa08c86b | 1022 | try_rsa_authentication(options.identity_files[i])) |
a306f2dd | 1023 | return; |
1024 | } | |
d464095c | 1025 | /* Try challenge response authentication if the server supports it. */ |
a306f2dd | 1026 | if ((supported_authentications & (1 << SSH_AUTH_TIS)) && |
d464095c | 1027 | options.challenge_reponse_authentication && !options.batch_mode) { |
1028 | if (try_challenge_reponse_authentication()) | |
a306f2dd | 1029 | return; |
1030 | } | |
1031 | /* Try password authentication if the server supports it. */ | |
1032 | if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) && | |
1033 | options.password_authentication && !options.batch_mode) { | |
1034 | char prompt[80]; | |
1035 | ||
b3b9ad8e | 1036 | snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", |
a306f2dd | 1037 | server_user, host); |
1038 | if (try_password_authentication(prompt)) | |
1039 | return; | |
1040 | } | |
1041 | /* All authentication methods have failed. Exit with an error message. */ | |
1042 | fatal("Permission denied."); | |
1043 | /* NOTREACHED */ | |
1044 | } |