1 /* $OpenBSD: auth2.c,v 1.135 2015/01/19 20:07:45 markus Exp $ */
3 * Copyright (c) 2000 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include <sys/types.h>
52 #include "pathnames.h"
55 #include "blacklist_client.h"
60 #include "monitor_wrap.h"
63 extern ServerOptions options;
64 extern u_char *session_id2;
65 extern u_int session_id2_len;
66 extern Buffer loginmsg;
70 extern Authmethod method_none;
71 extern Authmethod method_pubkey;
72 extern Authmethod method_passwd;
73 extern Authmethod method_kbdint;
74 extern Authmethod method_hostbased;
76 extern Authmethod method_gssapi;
79 Authmethod *authmethods[] = {
93 static int input_service_request(int, u_int32_t, void *);
94 static int input_userauth_request(int, u_int32_t, void *);
97 static Authmethod *authmethod_lookup(Authctxt *, const char *);
98 static char *authmethods_get(Authctxt *authctxt);
100 #define MATCH_NONE 0 /* method or submethod mismatch */
101 #define MATCH_METHOD 1 /* method matches (no submethod specified) */
102 #define MATCH_BOTH 2 /* method and submethod match */
103 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
104 static int list_starts_with(const char *, const char *, const char *);
107 auth2_read_banner(void)
114 if ((fd = open(options.banner, O_RDONLY)) == -1)
116 if (fstat(fd, &st) == -1) {
120 if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
125 len = (size_t)st.st_size; /* truncate */
126 banner = xmalloc(len + 1);
127 n = atomicio(read, fd, banner, len);
140 userauth_send_banner(const char *msg)
142 if (datafellows & SSH_BUG_BANNER)
145 packet_start(SSH2_MSG_USERAUTH_BANNER);
146 packet_put_cstring(msg);
147 packet_put_cstring(""); /* language, unused */
149 debug("%s: sent", __func__);
153 userauth_banner(void)
157 if (options.banner == NULL || (datafellows & SSH_BUG_BANNER) != 0)
160 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
162 userauth_send_banner(banner);
169 * loop until authctxt->success == TRUE
172 do_authentication2(Authctxt *authctxt)
174 dispatch_init(&dispatch_protocol_error);
175 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
176 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
181 input_service_request(int type, u_int32_t seq, void *ctxt)
183 Authctxt *authctxt = ctxt;
186 char *service = packet_get_cstring(&len);
189 if (authctxt == NULL)
190 fatal("input_service_request: no authctxt");
192 if (strcmp(service, "ssh-userauth") == 0) {
193 if (!authctxt->success) {
195 /* now we can handle user-auth requests */
196 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
199 /* XXX all other service requests are denied */
202 packet_start(SSH2_MSG_SERVICE_ACCEPT);
203 packet_put_cstring(service);
207 debug("bad service request %s", service);
208 packet_disconnect("bad service request %s", service);
216 input_userauth_request(int type, u_int32_t seq, void *ctxt)
218 Authctxt *authctxt = ctxt;
219 Authmethod *m = NULL;
220 char *user, *service, *method, *style = NULL;
221 int authenticated = 0;
222 #ifdef HAVE_LOGIN_CAP
224 const char *from_host, *from_ip;
226 from_host = get_canonical_hostname(options.use_dns);
227 from_ip = get_remote_ipaddr();
230 if (authctxt == NULL)
231 fatal("input_userauth_request: no authctxt");
233 user = packet_get_cstring(NULL);
234 service = packet_get_cstring(NULL);
235 method = packet_get_cstring(NULL);
236 debug("userauth-request for user %s service %s method %s", user, service, method);
237 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
239 if ((style = strchr(user, ':')) != NULL)
242 if (authctxt->attempt++ == 0) {
243 /* setup auth context */
244 authctxt->pw = PRIVSEP(getpwnamallow(user));
245 authctxt->user = xstrdup(user);
246 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
248 debug2("input_userauth_request: setting up authctxt for %s", user);
250 logit("input_userauth_request: invalid user %s", user);
251 authctxt->pw = fakepw();
252 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL);
253 #ifdef SSH_AUDIT_EVENTS
254 PRIVSEP(audit_event(SSH_INVALID_USER));
259 PRIVSEP(start_pam(authctxt));
261 setproctitle("%s%s", authctxt->valid ? user : "unknown",
262 use_privsep ? " [net]" : "");
263 authctxt->service = xstrdup(service);
264 authctxt->style = style ? xstrdup(style) : NULL;
266 mm_inform_authserv(service, style);
268 if (auth2_setup_methods_lists(authctxt) != 0)
269 packet_disconnect("no authentication methods enabled");
270 } else if (strcmp(user, authctxt->user) != 0 ||
271 strcmp(service, authctxt->service) != 0) {
272 packet_disconnect("Change of username or service not allowed: "
273 "(%s,%s) -> (%s,%s)",
274 authctxt->user, authctxt->service, user, service);
277 #ifdef HAVE_LOGIN_CAP
278 if (authctxt->pw != NULL) {
279 lc = login_getpwclass(authctxt->pw);
281 lc = login_getclassbyname(NULL, authctxt->pw);
282 if (!auth_hostok(lc, from_host, from_ip)) {
283 logit("Denied connection for %.200s from %.200s [%.200s].",
284 authctxt->pw->pw_name, from_host, from_ip);
285 packet_disconnect("Sorry, you are not allowed to connect.");
287 if (!auth_timeok(lc, time(NULL))) {
288 logit("LOGIN %.200s REFUSED (TIME) FROM %.200s",
289 authctxt->pw->pw_name, from_host);
290 packet_disconnect("Logins not available right now.");
295 #endif /* HAVE_LOGIN_CAP */
298 auth2_challenge_stop(authctxt);
301 /* XXX move to auth2_gssapi_stop() */
302 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
303 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
306 authctxt->postponed = 0;
307 authctxt->server_caused_failure = 0;
309 /* try to authenticate user */
310 m = authmethod_lookup(authctxt, method);
311 if (m != NULL && authctxt->failures < options.max_authtries) {
312 debug2("input_userauth_request: try method %s", method);
313 authenticated = m->userauth(authctxt);
315 userauth_finish(authctxt, authenticated, method, NULL);
324 userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
325 const char *submethod)
330 if (!authctxt->valid && authenticated)
331 fatal("INTERNAL ERROR: authenticated invalid user %s",
333 if (authenticated && authctxt->postponed)
334 fatal("INTERNAL ERROR: authenticated and postponed");
336 /* Special handling for root */
337 if (authenticated && authctxt->pw->pw_uid == 0 &&
338 !auth_root_allowed(method)) {
340 #ifdef SSH_AUDIT_EVENTS
341 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
345 if (authenticated && options.num_auth_methods != 0) {
346 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
352 /* Log before sending the reply */
353 auth_log(authctxt, authenticated, partial, method, submethod);
355 if (authctxt->postponed)
359 if (options.use_pam && authenticated) {
360 if (!PRIVSEP(do_pam_account())) {
361 /* if PAM returned a message, send it to the user */
362 if (buffer_len(&loginmsg) > 0) {
363 buffer_append(&loginmsg, "\0", 1);
364 userauth_send_banner(buffer_ptr(&loginmsg));
367 fatal("Access denied for user %s by PAM account "
368 "configuration", authctxt->user);
374 if (authenticated && cray_access_denied(authctxt->user)) {
376 fatal("Access denied for user %s.", authctxt->user);
380 if (authenticated == 1) {
381 /* turn off userauth */
382 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
383 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
386 /* now we can break out */
387 authctxt->success = 1;
390 /* Allow initial try of "none" auth without failure penalty */
391 if (!partial && !authctxt->server_caused_failure &&
392 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
393 authctxt->failures++;
394 if (authctxt->failures >= options.max_authtries) {
395 #ifdef SSH_AUDIT_EVENTS
396 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
398 auth_maxtries_exceeded(authctxt);
400 methods = authmethods_get(authctxt);
401 debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
403 packet_start(SSH2_MSG_USERAUTH_FAILURE);
404 packet_put_cstring(methods);
405 packet_put_char(partial);
413 * Checks whether method is allowed by at least one AuthenticationMethods
414 * methods list. Returns 1 if allowed, or no methods lists configured.
418 auth2_method_allowed(Authctxt *authctxt, const char *method,
419 const char *submethod)
424 * NB. authctxt->num_auth_methods might be zero as a result of
425 * auth2_setup_methods_lists(), so check the configuration.
427 if (options.num_auth_methods == 0)
429 for (i = 0; i < authctxt->num_auth_methods; i++) {
430 if (list_starts_with(authctxt->auth_methods[i], method,
431 submethod) != MATCH_NONE)
438 authmethods_get(Authctxt *authctxt)
445 for (i = 0; authmethods[i] != NULL; i++) {
446 if (strcmp(authmethods[i]->name, "none") == 0)
448 if (authmethods[i]->enabled == NULL ||
449 *(authmethods[i]->enabled) == 0)
451 if (!auth2_method_allowed(authctxt, authmethods[i]->name,
454 if (buffer_len(&b) > 0)
455 buffer_append(&b, ",", 1);
456 buffer_append(&b, authmethods[i]->name,
457 strlen(authmethods[i]->name));
459 buffer_append(&b, "\0", 1);
460 list = xstrdup(buffer_ptr(&b));
466 authmethod_lookup(Authctxt *authctxt, const char *name)
471 for (i = 0; authmethods[i] != NULL; i++)
472 if (authmethods[i]->enabled != NULL &&
473 *(authmethods[i]->enabled) != 0 &&
474 strcmp(name, authmethods[i]->name) == 0 &&
475 auth2_method_allowed(authctxt,
476 authmethods[i]->name, NULL))
477 return authmethods[i];
478 debug2("Unrecognized authentication method name: %s",
479 name ? name : "NULL");
484 * Check a comma-separated list of methods for validity. Is need_enable is
485 * non-zero, then also require that the methods are enabled.
486 * Returns 0 on success or -1 if the methods list is invalid.
489 auth2_methods_valid(const char *_methods, int need_enable)
491 char *methods, *omethods, *method, *p;
495 if (*_methods == '\0') {
496 error("empty authentication method list");
499 omethods = methods = xstrdup(_methods);
500 while ((method = strsep(&methods, ",")) != NULL) {
501 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
502 if ((p = strchr(method, ':')) != NULL)
504 if (strcmp(method, authmethods[i]->name) != 0)
507 if (authmethods[i]->enabled == NULL ||
508 *(authmethods[i]->enabled) == 0) {
509 error("Disabled method \"%s\" in "
510 "AuthenticationMethods list \"%s\"",
519 error("Unknown authentication method \"%s\" in list",
531 * Prune the AuthenticationMethods supplied in the configuration, removing
532 * any methods lists that include disabled methods. Note that this might
533 * leave authctxt->num_auth_methods == 0, even when multiple required auth
534 * has been requested. For this reason, all tests for whether multiple is
535 * enabled should consult options.num_auth_methods directly.
538 auth2_setup_methods_lists(Authctxt *authctxt)
542 if (options.num_auth_methods == 0)
544 debug3("%s: checking methods", __func__);
545 authctxt->auth_methods = xcalloc(options.num_auth_methods,
546 sizeof(*authctxt->auth_methods));
547 authctxt->num_auth_methods = 0;
548 for (i = 0; i < options.num_auth_methods; i++) {
549 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
550 logit("Authentication methods list \"%s\" contains "
551 "disabled method, skipping",
552 options.auth_methods[i]);
555 debug("authentication methods list %d: %s",
556 authctxt->num_auth_methods, options.auth_methods[i]);
557 authctxt->auth_methods[authctxt->num_auth_methods++] =
558 xstrdup(options.auth_methods[i]);
560 if (authctxt->num_auth_methods == 0) {
561 error("No AuthenticationMethods left after eliminating "
569 list_starts_with(const char *methods, const char *method,
570 const char *submethod)
572 size_t l = strlen(method);
576 if (strncmp(methods, method, l) != 0)
579 match = MATCH_METHOD;
582 return MATCH_PARTIAL;
583 l = strlen(submethod);
585 if (strncmp(submethod, p, l))
590 if (*p != ',' && *p != '\0')
596 * Remove method from the start of a comma-separated list of methods.
597 * Returns 0 if the list of methods did not start with that method or 1
601 remove_method(char **methods, const char *method, const char *submethod)
603 char *omethods = *methods, *p;
604 size_t l = strlen(method);
607 match = list_starts_with(omethods, method, submethod);
608 if (match != MATCH_METHOD && match != MATCH_BOTH)
611 if (submethod && match == MATCH_BOTH)
612 p += 1 + strlen(submethod); /* include colon */
615 *methods = xstrdup(p);
621 * Called after successful authentication. Will remove the successful method
622 * from the start of each list in which it occurs. If it was the last method
623 * in any list, then authentication is deemed successful.
624 * Returns 1 if the method completed any authentication list or 0 otherwise.
627 auth2_update_methods_lists(Authctxt *authctxt, const char *method,
628 const char *submethod)
632 debug3("%s: updating methods list after \"%s\"", __func__, method);
633 for (i = 0; i < authctxt->num_auth_methods; i++) {
634 if (!remove_method(&(authctxt->auth_methods[i]), method,
638 if (*authctxt->auth_methods[i] == '\0') {
639 debug2("authentication methods list %d complete", i);
642 debug3("authentication methods list %d remaining: \"%s\"",
643 i, authctxt->auth_methods[i]);
645 /* This should not happen, but would be bad if it did */
647 fatal("%s: method not in AuthenticationMethods", __func__);