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-rw-r--r--other/openssh-reverse/auth1.c536
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diff --git a/other/openssh-reverse/auth1.c b/other/openssh-reverse/auth1.c
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1/*
2 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
3 * All rights reserved
4 */
5
6#include "includes.h"
7RCSID("$OpenBSD: auth1.c,v 1.2 2000/04/29 18:11:52 markus Exp $");
8
9#include "xmalloc.h"
10#include "rsa.h"
11#include "ssh.h"
12#include "packet.h"
13#include "buffer.h"
14#include "cipher.h"
15#include "mpaux.h"
16#include "servconf.h"
17#include "compat.h"
18#include "auth.h"
19#include "session.h"
20
21#ifdef HAVE_OSF_SIA
22# include <sia.h>
23# include <siad.h>
24#endif
25
26/* import */
27extern ServerOptions options;
28extern char *forced_command;
29#ifdef HAVE_OSF_SIA
30extern int saved_argc;
31extern char **saved_argv;
32#endif /* HAVE_OSF_SIA */
33
34/*
35 * convert ssh auth msg type into description
36 */
37char *
38get_authname(int type)
39{
40 static char buf[1024];
41 switch (type) {
42 case SSH_CMSG_AUTH_PASSWORD:
43 return "password";
44 case SSH_CMSG_AUTH_RSA:
45 return "rsa";
46 case SSH_CMSG_AUTH_RHOSTS_RSA:
47 return "rhosts-rsa";
48 case SSH_CMSG_AUTH_RHOSTS:
49 return "rhosts";
50#ifdef KRB4
51 case SSH_CMSG_AUTH_KERBEROS:
52 return "kerberos";
53#endif
54#ifdef SKEY
55 case SSH_CMSG_AUTH_TIS_RESPONSE:
56 return "s/key";
57#endif
58 }
59 snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
60 return buf;
61}
62
63/*
64 * The user does not exist or access is denied,
65 * but fake indication that authentication is needed.
66 */
67void
68do_fake_authloop1(char *user)
69{
70 int attempt = 0;
71
72 log("Faking authloop for illegal user %.200s from %.200s port %d",
73 user,
74 get_remote_ipaddr(),
75 get_remote_port());
76
77#ifdef WITH_AIXAUTHENTICATE
78 loginfailed(user,get_canonical_hostname(),"ssh");
79#endif /* WITH_AIXAUTHENTICATE */
80
81 /* Indicate that authentication is needed. */
82 packet_start(SSH_SMSG_FAILURE);
83 packet_send();
84 packet_write_wait();
85
86 /*
87 * Keep reading packets, and always respond with a failure. This is
88 * to avoid disclosing whether such a user really exists.
89 */
90 for (attempt = 1;; attempt++) {
91 /* Read a packet. This will not return if the client disconnects. */
92 int plen;
93#ifndef SKEY
94 (void)packet_read(&plen);
95#else /* SKEY */
96 int type = packet_read(&plen);
97 unsigned int dlen;
98 char *password, *skeyinfo;
99 password = NULL;
100 /* Try to send a fake s/key challenge. */
101 if (options.skey_authentication == 1 &&
102 (skeyinfo = skey_fake_keyinfo(user)) != NULL) {
103 if (type == SSH_CMSG_AUTH_TIS) {
104 packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
105 packet_put_string(skeyinfo, strlen(skeyinfo));
106 packet_send();
107 packet_write_wait();
108 continue;
109 } else if (type == SSH_CMSG_AUTH_PASSWORD &&
110 options.password_authentication &&
111 (password = packet_get_string(&dlen)) != NULL &&
112 dlen == 5 &&
113 strncasecmp(password, "s/key", 5) == 0 ) {
114 packet_send_debug(skeyinfo);
115 }
116 }
117 if (password != NULL)
118 xfree(password);
119#endif
120 if (attempt > AUTH_FAIL_MAX)
121 packet_disconnect(AUTH_FAIL_MSG, user);
122
123 /*
124 * Send failure. This should be indistinguishable from a
125 * failed authentication.
126 */
127 packet_start(SSH_SMSG_FAILURE);
128 packet_send();
129 packet_write_wait();
130 }
131 /* NOTREACHED */
132 abort();
133}
134
135/*
136 * read packets and try to authenticate local user *pw.
137 * return if authentication is successfull
138 */
139void
140do_authloop(struct passwd * pw)
141{
142 int attempt = 0;
143 unsigned int bits;
144 RSA *client_host_key;
145 BIGNUM *n;
146 char *client_user = NULL, *password = NULL;
147 char user[1024];
148 unsigned int dlen;
149 int plen, nlen, elen;
150 unsigned int ulen;
151 int type = 0;
152 void (*authlog) (const char *fmt,...) = verbose;
153
154 /* Indicate that authentication is needed. */
155 packet_start(SSH_SMSG_FAILURE);
156 packet_send();
157 packet_write_wait();
158
159 for (attempt = 1;; attempt++) {
160 int authenticated = 0;
161 strlcpy(user, "", sizeof user);
162
163 /* Get a packet from the client. */
164 type = packet_read(&plen);
165
166 /* Process the packet. */
167 switch (type) {
168#ifdef AFS
169 case SSH_CMSG_HAVE_KERBEROS_TGT:
170 if (!options.kerberos_tgt_passing) {
171 /* packet_get_all(); */
172 verbose("Kerberos tgt passing disabled.");
173 break;
174 } else {
175 /* Accept Kerberos tgt. */
176 char *tgt = packet_get_string(&dlen);
177 packet_integrity_check(plen, 4 + dlen, type);
178 if (!auth_kerberos_tgt(pw, tgt))
179 verbose("Kerberos tgt REFUSED for %s", pw->pw_name);
180 xfree(tgt);
181 }
182 continue;
183
184 case SSH_CMSG_HAVE_AFS_TOKEN:
185 if (!options.afs_token_passing || !k_hasafs()) {
186 /* packet_get_all(); */
187 verbose("AFS token passing disabled.");
188 break;
189 } else {
190 /* Accept AFS token. */
191 char *token_string = packet_get_string(&dlen);
192 packet_integrity_check(plen, 4 + dlen, type);
193 if (!auth_afs_token(pw, token_string))
194 verbose("AFS token REFUSED for %s", pw->pw_name);
195 xfree(token_string);
196 }
197 continue;
198#endif /* AFS */
199#ifdef KRB4
200 case SSH_CMSG_AUTH_KERBEROS:
201 if (!options.kerberos_authentication) {
202 /* packet_get_all(); */
203 verbose("Kerberos authentication disabled.");
204 break;
205 } else {
206 /* Try Kerberos v4 authentication. */
207 KTEXT_ST auth;
208 char *tkt_user = NULL;
209 char *kdata = packet_get_string((unsigned int *) &auth.length);
210 packet_integrity_check(plen, 4 + auth.length, type);
211
212 if (auth.length < MAX_KTXT_LEN)
213 memcpy(auth.dat, kdata, auth.length);
214 xfree(kdata);
215
216 authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user);
217
218 if (authenticated) {
219 snprintf(user, sizeof user, " tktuser %s", tkt_user);
220 xfree(tkt_user);
221 }
222 }
223 break;
224#endif /* KRB4 */
225
226 case SSH_CMSG_AUTH_RHOSTS:
227 if (!options.rhosts_authentication) {
228 verbose("Rhosts authentication disabled.");
229 break;
230 }
231 /*
232 * Get client user name. Note that we just have to
233 * trust the client; this is one reason why rhosts
234 * authentication is insecure. (Another is
235 * IP-spoofing on a local network.)
236 */
237 client_user = packet_get_string(&ulen);
238 packet_integrity_check(plen, 4 + ulen, type);
239
240 /* Try to authenticate using /etc/hosts.equiv and
241 .rhosts. */
242 authenticated = auth_rhosts(pw, client_user);
243
244 snprintf(user, sizeof user, " ruser %s", client_user);
245 break;
246
247 case SSH_CMSG_AUTH_RHOSTS_RSA:
248 if (!options.rhosts_rsa_authentication) {
249 verbose("Rhosts with RSA authentication disabled.");
250 break;
251 }
252 /*
253 * Get client user name. Note that we just have to
254 * trust the client; root on the client machine can
255 * claim to be any user.
256 */
257 client_user = packet_get_string(&ulen);
258
259 /* Get the client host key. */
260 client_host_key = RSA_new();
261 if (client_host_key == NULL)
262 fatal("RSA_new failed");
263 client_host_key->e = BN_new();
264 client_host_key->n = BN_new();
265 if (client_host_key->e == NULL || client_host_key->n == NULL)
266 fatal("BN_new failed");
267 bits = packet_get_int();
268 packet_get_bignum(client_host_key->e, &elen);
269 packet_get_bignum(client_host_key->n, &nlen);
270
271 if (bits != BN_num_bits(client_host_key->n))
272 log("Warning: keysize mismatch for client_host_key: "
273 "actual %d, announced %d", BN_num_bits(client_host_key->n), bits);
274 packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);
275
276 authenticated = auth_rhosts_rsa(pw, client_user, client_host_key);
277 RSA_free(client_host_key);
278
279 snprintf(user, sizeof user, " ruser %s", client_user);
280 break;
281
282 case SSH_CMSG_AUTH_RSA:
283 if (!options.rsa_authentication) {
284 verbose("RSA authentication disabled.");
285 break;
286 }
287 /* RSA authentication requested. */
288 n = BN_new();
289 packet_get_bignum(n, &nlen);
290 packet_integrity_check(plen, nlen, type);
291 authenticated = auth_rsa(pw, n);
292 BN_clear_free(n);
293 break;
294
295 case SSH_CMSG_AUTH_PASSWORD:
296 if (!options.password_authentication) {
297 verbose("Password authentication disabled.");
298 break;
299 }
300 /*
301 * Read user password. It is in plain text, but was
302 * transmitted over the encrypted channel so it is
303 * not visible to an outside observer.
304 */
305 password = packet_get_string(&dlen);
306 packet_integrity_check(plen, 4 + dlen, type);
307
308#ifdef USE_PAM
309 /* Do PAM auth with password */
310 authenticated = auth_pam_password(pw, password);
311#elif defined(HAVE_OSF_SIA)
312 /* Do SIA auth with password */
313 if (sia_validate_user(NULL, saved_argc, saved_argv,
314 get_canonical_hostname(), pw->pw_name, NULL, 0,
315 NULL, password) == SIASUCCESS) {
316 authenticated = 1;
317 }
318#else /* !USE_PAM && !HAVE_OSF_SIA */
319 /* Try authentication with the password. */
320 authenticated = auth_password(pw, password);
321#endif /* USE_PAM */
322
323 memset(password, 0, strlen(password));
324 xfree(password);
325 break;
326
327#ifdef SKEY
328 case SSH_CMSG_AUTH_TIS:
329 debug("rcvd SSH_CMSG_AUTH_TIS");
330 if (options.skey_authentication == 1) {
331 char *skeyinfo = skey_keyinfo(pw->pw_name);
332 if (skeyinfo == NULL) {
333 debug("generating fake skeyinfo for %.100s.", pw->pw_name);
334 skeyinfo = skey_fake_keyinfo(pw->pw_name);
335 }
336 if (skeyinfo != NULL) {
337 /* we send our s/key- in tis-challenge messages */
338 debug("sending challenge '%s'", skeyinfo);
339 packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
340 packet_put_string(skeyinfo, strlen(skeyinfo));
341 packet_send();
342 packet_write_wait();
343 continue;
344 }
345 }
346 break;
347 case SSH_CMSG_AUTH_TIS_RESPONSE:
348 debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
349 if (options.skey_authentication == 1) {
350 char *response = packet_get_string(&dlen);
351 debug("skey response == '%s'", response);
352 packet_integrity_check(plen, 4 + dlen, type);
353 authenticated = (skey_haskey(pw->pw_name) == 0 &&
354 skey_passcheck(pw->pw_name, response) != -1);
355 xfree(response);
356 }
357 break;
358#else
359 case SSH_CMSG_AUTH_TIS:
360 /* TIS Authentication is unsupported */
361 log("TIS authentication unsupported.");
362 break;
363#endif
364
365 default:
366 /*
367 * Any unknown messages will be ignored (and failure
368 * returned) during authentication.
369 */
370 log("Unknown message during authentication: type %d", type);
371 break;
372 }
373
374 /*
375 * Check if the user is logging in as root and root logins
376 * are disallowed.
377 * Note that root login is allowed for forced commands.
378 */
379 if (authenticated && pw->pw_uid == 0 && !options.permit_root_login) {
380 if (forced_command) {
381 log("Root login accepted for forced command.");
382 } else {
383 authenticated = 0;
384 log("ROOT LOGIN REFUSED FROM %.200s",
385 get_canonical_hostname());
386 }
387 }
388
389 /* Raise logging level */
390 if (authenticated ||
391 attempt == AUTH_FAIL_LOG ||
392 type == SSH_CMSG_AUTH_PASSWORD)
393 authlog = log;
394
395 authlog("%s %s for %.200s from %.200s port %d%s",
396 authenticated ? "Accepted" : "Failed",
397 get_authname(type),
398 pw->pw_uid == 0 ? "ROOT" : pw->pw_name,
399 get_remote_ipaddr(),
400 get_remote_port(),
401 user);
402
403#ifdef USE_PAM
404 if (authenticated) {
405 if (!do_pam_account(pw->pw_name, client_user)) {
406 if (client_user != NULL) {
407 xfree(client_user);
408 client_user = NULL;
409 }
410 do_fake_authloop1(pw->pw_name);
411 }
412 return;
413 }
414#else /* USE_PAM */
415 if (authenticated) {
416 return;
417 }
418#endif /* USE_PAM */
419
420 if (client_user != NULL) {
421 xfree(client_user);
422 client_user = NULL;
423 }
424
425 if (attempt > AUTH_FAIL_MAX) {
426#ifdef WITH_AIXAUTHENTICATE
427 loginfailed(pw->pw_name,get_canonical_hostname(),"ssh");
428#endif /* WITH_AIXAUTHENTICATE */
429 packet_disconnect(AUTH_FAIL_MSG, pw->pw_name);
430 }
431
432 /* Send a message indicating that the authentication attempt failed. */
433 packet_start(SSH_SMSG_FAILURE);
434 packet_send();
435 packet_write_wait();
436 }
437}
438
439/*
440 * Performs authentication of an incoming connection. Session key has already
441 * been exchanged and encryption is enabled.
442 */
443void
444do_authentication()
445{
446 struct passwd *pw, pwcopy;
447 int plen;
448 unsigned int ulen;
449 char *user;
450#ifdef WITH_AIXAUTHENTICATE
451 extern char *aixloginmsg;
452#endif /* WITH_AIXAUTHENTICATE */
453
454 /* Get the name of the user that we wish to log in as. */
455 packet_read_expect(&plen, SSH_CMSG_USER);
456
457 /* Get the user name. */
458 user = packet_get_string(&ulen);
459 packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER);
460
461 setproctitle("%s", user);
462
463#ifdef AFS
464 /* If machine has AFS, set process authentication group. */
465 if (k_hasafs()) {
466 k_setpag();
467 k_unlog();
468 }
469#endif /* AFS */
470
471 /* Verify that the user is a valid user. */
472 pw = getpwnam(user);
473 if (!pw || !allowed_user(pw))
474 do_fake_authloop1(user);
475 xfree(user);
476
477 /* Take a copy of the returned structure. */
478 memset(&pwcopy, 0, sizeof(pwcopy));
479 pwcopy.pw_name = xstrdup(pw->pw_name);
480 pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
481 pwcopy.pw_uid = pw->pw_uid;
482 pwcopy.pw_gid = pw->pw_gid;
483 pwcopy.pw_dir = xstrdup(pw->pw_dir);
484 pwcopy.pw_shell = xstrdup(pw->pw_shell);
485 pw = &pwcopy;
486
487#ifdef USE_PAM
488 start_pam(pw);
489#endif
490
491 /*
492 * If we are not running as root, the user must have the same uid as
493 * the server.
494 */
495 if (getuid() != 0 && pw->pw_uid != getuid())
496 packet_disconnect("Cannot change user when server not running as root.");
497
498 debug("Attempting authentication for %.100s.", pw->pw_name);
499
500 /* If the user has no password, accept authentication immediately. */
501 if (options.password_authentication &&
502#ifdef KRB4
503 (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
504#endif /* KRB4 */
505#ifdef USE_PAM
506 auth_pam_password(pw, "")) {
507#elif defined(HAVE_OSF_SIA)
508 (sia_validate_user(NULL, saved_argc, saved_argv,
509 get_canonical_hostname(), pw->pw_name, NULL, 0, NULL,
510 "") == SIASUCCESS)) {
511#else /* !HAVE_OSF_SIA && !USE_PAM */
512 auth_password(pw, "")) {
513#endif /* USE_PAM */
514 /* Authentication with empty password succeeded. */
515 log("Login for user %s from %.100s, accepted without authentication.",
516 pw->pw_name, get_remote_ipaddr());
517 } else {
518 /* Loop until the user has been authenticated or the
519 connection is closed, do_authloop() returns only if
520 authentication is successfull */
521 do_authloop(pw);
522 }
523
524 /* The user has been authenticated and accepted. */
525#ifdef WITH_AIXAUTHENTICATE
526 /* We don't have a pty yet, so just label the line as "ssh" */
527 if (loginsuccess(user,get_canonical_hostname(),"ssh",&aixloginmsg) < 0)
528 aixloginmsg = NULL;
529#endif /* WITH_AIXAUTHENTICATE */
530 packet_start(SSH_SMSG_SUCCESS);
531 packet_send();
532 packet_write_wait();
533
534 /* Perform session preparation. */
535 do_authenticated(pw);
536}