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3c0ef626 | 1 | /* |
2 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
3 | * All rights reserved | |
4 | * | |
5 | * As far as I am concerned, the code I have written for this software | |
6 | * can be used freely for any purpose. Any derived versions of this | |
7 | * software must be clearly marked as such, and if the derived work is | |
8 | * incompatible with the protocol description in the RFC file, it must be | |
9 | * called by a name other than "ssh" or "Secure Shell". | |
10 | */ | |
11 | ||
12 | #include "includes.h" | |
1e608e42 | 13 | RCSID("$OpenBSD: auth1.c,v 1.35 2002/02/03 17:53:25 markus Exp $"); |
3c0ef626 | 14 | |
15 | #include "xmalloc.h" | |
16 | #include "rsa.h" | |
17 | #include "ssh1.h" | |
099f4607 | 18 | #include "dispatch.h" |
3c0ef626 | 19 | #include "packet.h" |
20 | #include "buffer.h" | |
21 | #include "mpaux.h" | |
22 | #include "log.h" | |
23 | #include "servconf.h" | |
24 | #include "compat.h" | |
25 | #include "auth.h" | |
1e608e42 | 26 | #include "channels.h" |
3c0ef626 | 27 | #include "session.h" |
28 | #include "misc.h" | |
29 | #include "uidswap.h" | |
30 | ||
31 | /* import */ | |
32 | extern ServerOptions options; | |
33 | ||
099f4607 | 34 | #ifdef GSSAPI |
755621a1 | 35 | int userauth_gssapi(Authctxt *authctxt); |
36 | ||
099f4607 | 37 | void |
38 | auth1_gss_protocol_error(int type, u_int32_t plen, void *ctxt) | |
39 | { | |
40 | Authctxt *authctxt = ctxt; | |
41 | /* Other side told us to abort, dont need to tell him */ | |
42 | /* maybe we can us some other method. */ | |
43 | if (type == SSH_MSG_AUTH_GSSAPI_ABORT) { | |
44 | log("auth1: GSSAPI aborting"); | |
45 | dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN, NULL); | |
46 | authctxt->success = 1; /* get out of loop*/ | |
47 | return; | |
48 | } | |
49 | ||
50 | log("auth1: protocol error: type %d plen %d", type, plen); | |
51 | packet_disconnect("Protocol error during GSSAPI authentication: " | |
52 | "Unknown packet type %d", type); | |
53 | } | |
755621a1 | 54 | |
55 | /* | |
56 | * SSH1 GSSAPI clients may send us a user name of the form: | |
57 | * | |
58 | * (1) username:x:SSL Subject Name | |
59 | * or | |
60 | * (2) username:i:SSL Subject Name | |
61 | * or | |
62 | * (3) username | |
63 | * | |
64 | * if case 1, then uname is an explicit name (ssh -l uname). Keep this | |
65 | * name always, rewrite the user parameter to be just uname. We'll pull | |
66 | * the GSSAPI idenity out and deal with (or skip it) later. | |
67 | * | |
68 | * if case 2, then uname is implicit (user didn't use the -l option), so | |
69 | * use the default gridmap mapping and replace uname with whatever | |
70 | * the gridmap maps to. If the gridmap mapping fails, drop down | |
71 | * to just uname | |
72 | * | |
73 | * if case 3, then leave it be. | |
74 | * | |
75 | * This function may return the original pointer to the orginal string, | |
76 | * the original pointer to a modified string, or a completely new pointer. | |
77 | */ | |
78 | static char * | |
79 | ssh1_gssapi_parse_userstring(char *userstring) | |
80 | { | |
81 | char name_type = '\0'; /* explicit 'x' or implicit 'i' */ | |
82 | char *ssl_subject_name = NULL; | |
83 | char *delim = NULL; | |
84 | ||
85 | debug("Looking at username '%s' for gssapi-ssleay type name", userstring); | |
86 | if((delim = strchr(userstring, ':')) != NULL) { | |
87 | /* Parse and split into components */ | |
88 | ssl_subject_name = strchr(delim + 1, ':'); | |
89 | ||
90 | if (ssl_subject_name) { | |
91 | /* Successful parse, split into components */ | |
92 | *delim = '\0'; | |
93 | name_type = *(delim + 1); | |
94 | *ssl_subject_name = '\0'; | |
95 | ssl_subject_name++; | |
96 | ||
97 | debug("Name parsed. type = '%c'. ssl subject name is \"%s\"", | |
98 | name_type, ssl_subject_name); | |
99 | ||
100 | } else { | |
101 | ||
102 | debug("Don't understand name format. Letting it pass."); | |
103 | } | |
104 | } | |
105 | ||
106 | #ifdef GSI | |
107 | if(ssl_subject_name) { | |
108 | char *gridmapped_name = NULL; | |
109 | switch (name_type) { | |
110 | case 'x': | |
111 | debug("explicit name given, using %s as username", userstring); | |
112 | break; | |
113 | ||
114 | case 'i': | |
115 | /* gridmap check */ | |
116 | debug("implicit name given. gridmapping '%s'", ssl_subject_name); | |
117 | ||
118 | if(globus_gss_assist_gridmap(ssl_subject_name, | |
119 | &gridmapped_name) == 0) { | |
120 | userstring = gridmapped_name; | |
121 | debug("I gridmapped and got %s", userstring); | |
122 | ||
123 | } else { | |
124 | debug("I gridmapped and got null, reverting to %s", userstring); | |
125 | } | |
126 | break; | |
127 | ||
128 | default: | |
129 | debug("Unknown name type '%c'. Ignoring.", name_type); | |
130 | break; | |
131 | } | |
132 | } else { | |
133 | debug("didn't find any :'s so I assume it's just a user name"); | |
134 | } | |
135 | #endif /* GSI */ | |
136 | ||
137 | return userstring; | |
138 | } | |
099f4607 | 139 | #endif |
140 | ||
3c0ef626 | 141 | /* |
142 | * convert ssh auth msg type into description | |
143 | */ | |
144 | static char * | |
145 | get_authname(int type) | |
146 | { | |
147 | static char buf[1024]; | |
148 | switch (type) { | |
149 | case SSH_CMSG_AUTH_PASSWORD: | |
150 | return "password"; | |
151 | case SSH_CMSG_AUTH_RSA: | |
152 | return "rsa"; | |
153 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
154 | return "rhosts-rsa"; | |
155 | case SSH_CMSG_AUTH_RHOSTS: | |
156 | return "rhosts"; | |
157 | case SSH_CMSG_AUTH_TIS: | |
158 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
159 | return "challenge-response"; | |
160 | #if defined(KRB4) || defined(KRB5) | |
161 | case SSH_CMSG_AUTH_KERBEROS: | |
162 | return "kerberos"; | |
099f4607 | 163 | #endif |
164 | #if defined(GSSAPI) | |
165 | case SSH_CMSG_AUTH_GSSAPI: | |
166 | return "gssapi"; | |
3c0ef626 | 167 | #endif |
168 | } | |
169 | snprintf(buf, sizeof buf, "bad-auth-msg-%d", type); | |
170 | return buf; | |
171 | } | |
172 | ||
173 | /* | |
174 | * read packets, try to authenticate the user and | |
175 | * return only if authentication is successful | |
176 | */ | |
177 | static void | |
178 | do_authloop(Authctxt *authctxt) | |
179 | { | |
180 | int authenticated = 0; | |
181 | u_int bits; | |
1e608e42 | 182 | Key *client_host_key; |
3c0ef626 | 183 | BIGNUM *n; |
184 | char *client_user, *password; | |
185 | char info[1024]; | |
186 | u_int dlen; | |
3c0ef626 | 187 | u_int ulen; |
188 | int type = 0; | |
189 | struct passwd *pw = authctxt->pw; | |
190 | ||
191 | debug("Attempting authentication for %s%.100s.", | |
1e608e42 | 192 | authctxt->valid ? "" : "illegal user ", authctxt->user); |
3c0ef626 | 193 | |
194 | /* If the user has no password, accept authentication immediately. */ | |
195 | if (options.password_authentication && | |
196 | #if defined(KRB4) || defined(KRB5) | |
197 | (!options.kerberos_authentication || options.kerberos_or_local_passwd) && | |
198 | #endif | |
199 | #ifdef USE_PAM | |
200 | auth_pam_password(pw, "")) { | |
201 | #elif defined(HAVE_OSF_SIA) | |
202 | 0) { | |
203 | #else | |
204 | auth_password(authctxt, "")) { | |
205 | #endif | |
206 | auth_log(authctxt, 1, "without authentication", ""); | |
207 | return; | |
208 | } | |
209 | ||
210 | /* Indicate that authentication is needed. */ | |
211 | packet_start(SSH_SMSG_FAILURE); | |
212 | packet_send(); | |
213 | packet_write_wait(); | |
214 | ||
215 | client_user = NULL; | |
216 | ||
217 | for (;;) { | |
218 | /* default to fail */ | |
219 | authenticated = 0; | |
220 | ||
221 | info[0] = '\0'; | |
222 | ||
223 | /* Get a packet from the client. */ | |
1e608e42 | 224 | type = packet_read(); |
3c0ef626 | 225 | |
226 | /* Process the packet. */ | |
227 | switch (type) { | |
228 | ||
229 | #if defined(KRB4) || defined(KRB5) | |
230 | case SSH_CMSG_AUTH_KERBEROS: | |
231 | if (!options.kerberos_authentication) { | |
232 | verbose("Kerberos authentication disabled."); | |
233 | } else { | |
234 | char *kdata = packet_get_string(&dlen); | |
1e608e42 | 235 | packet_check_eom(); |
236 | ||
3c0ef626 | 237 | if (kdata[0] == 4) { /* KRB_PROT_VERSION */ |
238 | #ifdef KRB4 | |
239 | KTEXT_ST tkt; | |
1e608e42 | 240 | |
3c0ef626 | 241 | tkt.length = dlen; |
242 | if (tkt.length < MAX_KTXT_LEN) | |
243 | memcpy(tkt.dat, kdata, tkt.length); | |
1e608e42 | 244 | |
3c0ef626 | 245 | if (auth_krb4(authctxt, &tkt, &client_user)) { |
246 | authenticated = 1; | |
247 | snprintf(info, sizeof(info), | |
248 | " tktuser %.100s", | |
249 | client_user); | |
250 | } | |
251 | #endif /* KRB4 */ | |
252 | } else { | |
253 | #ifdef KRB5 | |
254 | krb5_data tkt; | |
255 | tkt.length = dlen; | |
256 | tkt.data = kdata; | |
1e608e42 | 257 | |
3c0ef626 | 258 | if (auth_krb5(authctxt, &tkt, &client_user)) { |
259 | authenticated = 1; | |
260 | snprintf(info, sizeof(info), | |
261 | " tktuser %.100s", | |
262 | client_user); | |
263 | } | |
264 | #endif /* KRB5 */ | |
265 | } | |
266 | xfree(kdata); | |
267 | } | |
268 | break; | |
269 | #endif /* KRB4 || KRB5 */ | |
0b582e46 | 270 | |
0b582e46 | 271 | #ifdef GSSAPI |
099f4607 | 272 | case SSH_CMSG_AUTH_GSSAPI: |
273 | if (!options.gss_authentication) { | |
274 | verbose("GSSAPI authentication disabled."); | |
275 | break; | |
276 | } | |
277 | /* | |
278 | * GSSAPI was first added to ssh1 in ssh-1.2.27, and | |
279 | * was added to the SecurtCRT product. In order | |
280 | * to continue operating with these, we will add | |
281 | * the equivelent GSSAPI support to SSH1. | |
282 | * Will use the gssapi routines from the ssh2 as | |
283 | * they are almost identical. But they use dispatch | |
284 | * so we need to setup the dispatch tables here | |
285 | * auth1.c for use only by the gssapi code. | |
286 | * Since we already have the packet, we will call | |
287 | * userauth_gssapi then start the dispatch loop. | |
288 | */ | |
289 | if (!authctxt->valid) { | |
290 | packet_disconnect("Authentication rejected for invalid user"); | |
291 | } | |
292 | dispatch_init(&auth1_gss_protocol_error); | |
293 | userauth_gssapi(authctxt); | |
294 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
295 | if (authctxt->postponed) { /* failed, try other methods */ | |
296 | authctxt->success = 0; | |
297 | authctxt->postponed = 0; | |
298 | break; | |
299 | } | |
300 | do_authenticated(authctxt); | |
301 | /* will only return if authenticated */ | |
302 | authenticated = 1; | |
303 | break; | |
0b582e46 | 304 | #endif /* GSSAPI */ |
3c0ef626 | 305 | |
306 | #if defined(AFS) || defined(KRB5) | |
307 | /* XXX - punt on backward compatibility here. */ | |
308 | case SSH_CMSG_HAVE_KERBEROS_TGT: | |
309 | packet_send_debug("Kerberos TGT passing disabled before authentication."); | |
310 | break; | |
311 | #ifdef AFS | |
312 | case SSH_CMSG_HAVE_AFS_TOKEN: | |
313 | packet_send_debug("AFS token passing disabled before authentication."); | |
314 | break; | |
315 | #endif /* AFS */ | |
316 | #endif /* AFS || KRB5 */ | |
1e608e42 | 317 | |
3c0ef626 | 318 | case SSH_CMSG_AUTH_RHOSTS: |
319 | if (!options.rhosts_authentication) { | |
320 | verbose("Rhosts authentication disabled."); | |
321 | break; | |
322 | } | |
323 | /* | |
324 | * Get client user name. Note that we just have to | |
325 | * trust the client; this is one reason why rhosts | |
326 | * authentication is insecure. (Another is | |
327 | * IP-spoofing on a local network.) | |
328 | */ | |
329 | client_user = packet_get_string(&ulen); | |
1e608e42 | 330 | packet_check_eom(); |
3c0ef626 | 331 | |
332 | /* Try to authenticate using /etc/hosts.equiv and .rhosts. */ | |
333 | authenticated = auth_rhosts(pw, client_user); | |
334 | ||
335 | snprintf(info, sizeof info, " ruser %.100s", client_user); | |
336 | break; | |
337 | ||
338 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
339 | if (!options.rhosts_rsa_authentication) { | |
340 | verbose("Rhosts with RSA authentication disabled."); | |
341 | break; | |
342 | } | |
343 | /* | |
344 | * Get client user name. Note that we just have to | |
345 | * trust the client; root on the client machine can | |
346 | * claim to be any user. | |
347 | */ | |
348 | client_user = packet_get_string(&ulen); | |
349 | ||
350 | /* Get the client host key. */ | |
1e608e42 | 351 | client_host_key = key_new(KEY_RSA1); |
3c0ef626 | 352 | bits = packet_get_int(); |
1e608e42 | 353 | packet_get_bignum(client_host_key->rsa->e); |
354 | packet_get_bignum(client_host_key->rsa->n); | |
3c0ef626 | 355 | |
1e608e42 | 356 | if (bits != BN_num_bits(client_host_key->rsa->n)) |
3c0ef626 | 357 | verbose("Warning: keysize mismatch for client_host_key: " |
1e608e42 | 358 | "actual %d, announced %d", |
359 | BN_num_bits(client_host_key->rsa->n), bits); | |
360 | packet_check_eom(); | |
3c0ef626 | 361 | |
1e608e42 | 362 | authenticated = auth_rhosts_rsa(pw, client_user, |
363 | client_host_key); | |
364 | key_free(client_host_key); | |
3c0ef626 | 365 | |
366 | snprintf(info, sizeof info, " ruser %.100s", client_user); | |
367 | break; | |
368 | ||
369 | case SSH_CMSG_AUTH_RSA: | |
370 | if (!options.rsa_authentication) { | |
371 | verbose("RSA authentication disabled."); | |
372 | break; | |
373 | } | |
374 | /* RSA authentication requested. */ | |
1e608e42 | 375 | if ((n = BN_new()) == NULL) |
376 | fatal("do_authloop: BN_new failed"); | |
377 | packet_get_bignum(n); | |
378 | packet_check_eom(); | |
3c0ef626 | 379 | authenticated = auth_rsa(pw, n); |
380 | BN_clear_free(n); | |
381 | break; | |
382 | ||
383 | case SSH_CMSG_AUTH_PASSWORD: | |
384 | if (!options.password_authentication) { | |
385 | verbose("Password authentication disabled."); | |
386 | break; | |
387 | } | |
388 | /* | |
389 | * Read user password. It is in plain text, but was | |
390 | * transmitted over the encrypted channel so it is | |
391 | * not visible to an outside observer. | |
392 | */ | |
393 | password = packet_get_string(&dlen); | |
1e608e42 | 394 | packet_check_eom(); |
3c0ef626 | 395 | |
396 | #ifdef USE_PAM | |
397 | /* Do PAM auth with password */ | |
398 | authenticated = auth_pam_password(pw, password); | |
399 | #elif defined(HAVE_OSF_SIA) | |
400 | /* Do SIA auth with password */ | |
401 | authenticated = auth_sia_password(authctxt->user, | |
402 | password); | |
403 | #else /* !USE_PAM && !HAVE_OSF_SIA */ | |
404 | /* Try authentication with the password. */ | |
405 | authenticated = auth_password(authctxt, password); | |
406 | #endif /* USE_PAM */ | |
407 | ||
408 | memset(password, 0, strlen(password)); | |
409 | xfree(password); | |
410 | break; | |
411 | ||
412 | case SSH_CMSG_AUTH_TIS: | |
413 | debug("rcvd SSH_CMSG_AUTH_TIS"); | |
414 | if (options.challenge_response_authentication == 1) { | |
415 | char *challenge = get_challenge(authctxt); | |
416 | if (challenge != NULL) { | |
417 | debug("sending challenge '%s'", challenge); | |
418 | packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); | |
419 | packet_put_cstring(challenge); | |
420 | xfree(challenge); | |
421 | packet_send(); | |
422 | packet_write_wait(); | |
423 | continue; | |
424 | } | |
425 | } | |
426 | break; | |
427 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
428 | debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE"); | |
429 | if (options.challenge_response_authentication == 1) { | |
430 | char *response = packet_get_string(&dlen); | |
431 | debug("got response '%s'", response); | |
1e608e42 | 432 | packet_check_eom(); |
3c0ef626 | 433 | authenticated = verify_response(authctxt, response); |
434 | memset(response, 'r', dlen); | |
435 | xfree(response); | |
436 | } | |
437 | break; | |
438 | ||
439 | default: | |
440 | /* | |
441 | * Any unknown messages will be ignored (and failure | |
442 | * returned) during authentication. | |
443 | */ | |
444 | log("Unknown message during authentication: type %d", type); | |
445 | break; | |
446 | } | |
447 | #ifdef BSD_AUTH | |
448 | if (authctxt->as) { | |
449 | auth_close(authctxt->as); | |
450 | authctxt->as = NULL; | |
451 | } | |
452 | #endif | |
453 | if (!authctxt->valid && authenticated) | |
454 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
455 | authctxt->user); | |
456 | ||
457 | #ifdef HAVE_CYGWIN | |
458 | if (authenticated && | |
1e608e42 | 459 | !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) { |
3c0ef626 | 460 | packet_disconnect("Authentication rejected for uid %d.", |
1e608e42 | 461 | pw == NULL ? -1 : pw->pw_uid); |
3c0ef626 | 462 | authenticated = 0; |
463 | } | |
464 | #else | |
465 | /* Special handling for root */ | |
466 | if (authenticated && authctxt->pw->pw_uid == 0 && | |
467 | !auth_root_allowed(get_authname(type))) | |
468 | authenticated = 0; | |
469 | #endif | |
470 | #ifdef USE_PAM | |
471 | if (authenticated && !do_pam_account(pw->pw_name, client_user)) | |
472 | authenticated = 0; | |
473 | #endif | |
474 | ||
475 | /* Log before sending the reply */ | |
476 | auth_log(authctxt, authenticated, get_authname(type), info); | |
477 | ||
478 | if (client_user != NULL) { | |
479 | xfree(client_user); | |
480 | client_user = NULL; | |
481 | } | |
482 | ||
483 | if (authenticated) | |
484 | return; | |
485 | ||
486 | if (authctxt->failures++ > AUTH_FAIL_MAX) { | |
487 | #ifdef WITH_AIXAUTHENTICATE | |
488 | loginfailed(authctxt->user, | |
1e608e42 | 489 | get_canonical_hostname(options.verify_reverse_mapping), |
3c0ef626 | 490 | "ssh"); |
491 | #endif /* WITH_AIXAUTHENTICATE */ | |
492 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); | |
493 | } | |
494 | ||
495 | packet_start(SSH_SMSG_FAILURE); | |
496 | packet_send(); | |
497 | packet_write_wait(); | |
498 | } | |
499 | } | |
500 | ||
501 | /* | |
502 | * Performs authentication of an incoming connection. Session key has already | |
503 | * been exchanged and encryption is enabled. | |
504 | */ | |
505 | void | |
1e608e42 | 506 | do_authentication(void) |
3c0ef626 | 507 | { |
508 | Authctxt *authctxt; | |
509 | struct passwd *pw; | |
3c0ef626 | 510 | u_int ulen; |
511 | char *p, *user, *style = NULL; | |
512 | ||
513 | /* Get the name of the user that we wish to log in as. */ | |
1e608e42 | 514 | packet_read_expect(SSH_CMSG_USER); |
3c0ef626 | 515 | |
516 | /* Get the user name. */ | |
517 | user = packet_get_string(&ulen); | |
1e608e42 | 518 | packet_check_eom(); |
3c0ef626 | 519 | |
755621a1 | 520 | #ifdef GSSAPI |
0b582e46 | 521 | /* Parse GSSAPI identity from userstring */ |
755621a1 | 522 | user = ssh1_gssapi_parse_userstring(user); |
0b582e46 | 523 | #endif /* GSSAPI */ |
0b582e46 | 524 | |
3c0ef626 | 525 | if ((style = strchr(user, ':')) != NULL) |
526 | *style++ = '\0'; | |
527 | ||
528 | /* XXX - SSH.com Kerberos v5 braindeath. */ | |
529 | if ((p = strchr(user, '@')) != NULL) | |
530 | *p = '\0'; | |
1e608e42 | 531 | |
3c0ef626 | 532 | authctxt = authctxt_new(); |
533 | authctxt->user = user; | |
534 | authctxt->style = style; | |
535 | ||
536 | /* Verify that the user is a valid user. */ | |
537 | pw = getpwnam(user); | |
538 | if (pw && allowed_user(pw)) { | |
539 | authctxt->valid = 1; | |
540 | pw = pwcopy(pw); | |
541 | } else { | |
542 | debug("do_authentication: illegal user %s", user); | |
543 | pw = NULL; | |
544 | } | |
545 | authctxt->pw = pw; | |
546 | ||
547 | setproctitle("%s", pw ? user : "unknown"); | |
548 | ||
549 | #ifdef USE_PAM | |
1e608e42 | 550 | start_pam(pw == NULL ? "NOUSER" : user); |
3c0ef626 | 551 | #endif |
552 | ||
553 | /* | |
554 | * If we are not running as root, the user must have the same uid as | |
555 | * the server. (Unless you are running Windows) | |
556 | */ | |
557 | #ifndef HAVE_CYGWIN | |
558 | if (getuid() != 0 && pw && pw->pw_uid != getuid()) | |
559 | packet_disconnect("Cannot change user when server not running as root."); | |
560 | #endif | |
561 | ||
562 | /* | |
563 | * Loop until the user has been authenticated or the connection is | |
564 | * closed, do_authloop() returns only if authentication is successful | |
565 | */ | |
566 | do_authloop(authctxt); | |
567 | ||
568 | /* The user has been authenticated and accepted. */ | |
569 | packet_start(SSH_SMSG_SUCCESS); | |
570 | packet_send(); | |
571 | packet_write_wait(); | |
572 | ||
573 | /* Perform session preparation. */ | |
574 | do_authenticated(authctxt); | |
575 | } |