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"
59 #include "monitor_wrap.h"
62 extern ServerOptions options;
63 extern u_char *session_id2;
64 extern u_int session_id2_len;
65 extern Buffer loginmsg;
69 extern Authmethod method_none;
70 extern Authmethod method_pubkey;
71 extern Authmethod method_passwd;
72 extern Authmethod method_kbdint;
73 extern Authmethod method_hostbased;
75 extern Authmethod method_gssapi;
78 Authmethod *authmethods[] = {
92 static int input_service_request(int, u_int32_t, void *);
93 static int input_userauth_request(int, u_int32_t, void *);
96 static Authmethod *authmethod_lookup(Authctxt *, const char *);
97 static char *authmethods_get(Authctxt *authctxt);
99 #define MATCH_NONE 0 /* method or submethod mismatch */
100 #define MATCH_METHOD 1 /* method matches (no submethod specified) */
101 #define MATCH_BOTH 2 /* method and submethod match */
102 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
103 static int list_starts_with(const char *, const char *, const char *);
106 auth2_read_banner(void)
113 if ((fd = open(options.banner, O_RDONLY)) == -1)
115 if (fstat(fd, &st) == -1) {
119 if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
124 len = (size_t)st.st_size; /* truncate */
125 banner = xmalloc(len + 1);
126 n = atomicio(read, fd, banner, len);
139 userauth_send_banner(const char *msg)
141 if (datafellows & SSH_BUG_BANNER)
144 packet_start(SSH2_MSG_USERAUTH_BANNER);
145 packet_put_cstring(msg);
146 packet_put_cstring(""); /* language, unused */
148 debug("%s: sent", __func__);
152 userauth_banner(void)
156 if (options.banner == NULL || (datafellows & SSH_BUG_BANNER) != 0)
159 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
161 userauth_send_banner(banner);
168 * loop until authctxt->success == TRUE
171 do_authentication2(Authctxt *authctxt)
173 dispatch_init(&dispatch_protocol_error);
174 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
175 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
180 input_service_request(int type, u_int32_t seq, void *ctxt)
182 Authctxt *authctxt = ctxt;
185 char *service = packet_get_cstring(&len);
188 if (authctxt == NULL)
189 fatal("input_service_request: no authctxt");
191 if (strcmp(service, "ssh-userauth") == 0) {
192 if (!authctxt->success) {
194 /* now we can handle user-auth requests */
195 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
198 /* XXX all other service requests are denied */
201 packet_start(SSH2_MSG_SERVICE_ACCEPT);
202 packet_put_cstring(service);
206 debug("bad service request %s", service);
207 packet_disconnect("bad service request %s", service);
215 input_userauth_request(int type, u_int32_t seq, void *ctxt)
217 Authctxt *authctxt = ctxt;
218 Authmethod *m = NULL;
219 char *user, *service, *method, *style = NULL;
220 int authenticated = 0;
221 #ifdef HAVE_LOGIN_CAP
223 const char *from_host, *from_ip;
225 from_host = get_canonical_hostname(options.use_dns);
226 from_ip = get_remote_ipaddr();
229 if (authctxt == NULL)
230 fatal("input_userauth_request: no authctxt");
232 user = packet_get_cstring(NULL);
233 service = packet_get_cstring(NULL);
234 method = packet_get_cstring(NULL);
235 debug("userauth-request for user %s service %s method %s", user, service, method);
236 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
238 if ((style = strchr(user, ':')) != NULL)
241 if (authctxt->attempt++ == 0) {
242 /* setup auth context */
243 authctxt->pw = PRIVSEP(getpwnamallow(user));
244 authctxt->user = xstrdup(user);
245 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
247 debug2("input_userauth_request: setting up authctxt for %s", user);
249 logit("input_userauth_request: invalid user %s", user);
250 authctxt->pw = fakepw();
251 #ifdef SSH_AUDIT_EVENTS
252 PRIVSEP(audit_event(SSH_INVALID_USER));
257 PRIVSEP(start_pam(authctxt));
259 setproctitle("%s%s", authctxt->valid ? user : "unknown",
260 use_privsep ? " [net]" : "");
261 authctxt->service = xstrdup(service);
262 authctxt->style = style ? xstrdup(style) : NULL;
264 mm_inform_authserv(service, style);
266 if (auth2_setup_methods_lists(authctxt) != 0)
267 packet_disconnect("no authentication methods enabled");
268 } else if (strcmp(user, authctxt->user) != 0 ||
269 strcmp(service, authctxt->service) != 0) {
270 packet_disconnect("Change of username or service not allowed: "
271 "(%s,%s) -> (%s,%s)",
272 authctxt->user, authctxt->service, user, service);
275 #ifdef HAVE_LOGIN_CAP
276 if (authctxt->pw != NULL) {
277 lc = login_getpwclass(authctxt->pw);
279 lc = login_getclassbyname(NULL, authctxt->pw);
280 if (!auth_hostok(lc, from_host, from_ip)) {
281 logit("Denied connection for %.200s from %.200s [%.200s].",
282 authctxt->pw->pw_name, from_host, from_ip);
283 packet_disconnect("Sorry, you are not allowed to connect.");
285 if (!auth_timeok(lc, time(NULL))) {
286 logit("LOGIN %.200s REFUSED (TIME) FROM %.200s",
287 authctxt->pw->pw_name, from_host);
288 packet_disconnect("Logins not available right now.");
293 #endif /* HAVE_LOGIN_CAP */
296 auth2_challenge_stop(authctxt);
299 /* XXX move to auth2_gssapi_stop() */
300 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
301 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
304 authctxt->postponed = 0;
305 authctxt->server_caused_failure = 0;
307 /* try to authenticate user */
308 m = authmethod_lookup(authctxt, method);
309 if (m != NULL && authctxt->failures < options.max_authtries) {
310 debug2("input_userauth_request: try method %s", method);
311 authenticated = m->userauth(authctxt);
313 userauth_finish(authctxt, authenticated, method, NULL);
322 userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
323 const char *submethod)
328 if (!authctxt->valid && authenticated)
329 fatal("INTERNAL ERROR: authenticated invalid user %s",
331 if (authenticated && authctxt->postponed)
332 fatal("INTERNAL ERROR: authenticated and postponed");
334 /* Special handling for root */
335 if (authenticated && authctxt->pw->pw_uid == 0 &&
336 !auth_root_allowed(method)) {
338 #ifdef SSH_AUDIT_EVENTS
339 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
343 if (authenticated && options.num_auth_methods != 0) {
344 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
350 /* Log before sending the reply */
351 auth_log(authctxt, authenticated, partial, method, submethod);
353 if (authctxt->postponed)
357 if (options.use_pam && authenticated) {
358 if (!PRIVSEP(do_pam_account())) {
359 /* if PAM returned a message, send it to the user */
360 if (buffer_len(&loginmsg) > 0) {
361 buffer_append(&loginmsg, "\0", 1);
362 userauth_send_banner(buffer_ptr(&loginmsg));
365 fatal("Access denied for user %s by PAM account "
366 "configuration", authctxt->user);
372 if (authenticated && cray_access_denied(authctxt->user)) {
374 fatal("Access denied for user %s.", authctxt->user);
378 if (authenticated == 1) {
379 /* turn off userauth */
380 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
381 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
384 /* now we can break out */
385 authctxt->success = 1;
388 /* Allow initial try of "none" auth without failure penalty */
389 if (!partial && !authctxt->server_caused_failure &&
390 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
391 authctxt->failures++;
392 if (authctxt->failures >= options.max_authtries) {
393 #ifdef SSH_AUDIT_EVENTS
394 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
396 auth_maxtries_exceeded(authctxt);
398 methods = authmethods_get(authctxt);
399 debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
401 packet_start(SSH2_MSG_USERAUTH_FAILURE);
402 packet_put_cstring(methods);
403 packet_put_char(partial);
411 * Checks whether method is allowed by at least one AuthenticationMethods
412 * methods list. Returns 1 if allowed, or no methods lists configured.
416 auth2_method_allowed(Authctxt *authctxt, const char *method,
417 const char *submethod)
422 * NB. authctxt->num_auth_methods might be zero as a result of
423 * auth2_setup_methods_lists(), so check the configuration.
425 if (options.num_auth_methods == 0)
427 for (i = 0; i < authctxt->num_auth_methods; i++) {
428 if (list_starts_with(authctxt->auth_methods[i], method,
429 submethod) != MATCH_NONE)
436 authmethods_get(Authctxt *authctxt)
443 for (i = 0; authmethods[i] != NULL; i++) {
444 if (strcmp(authmethods[i]->name, "none") == 0)
446 if (authmethods[i]->enabled == NULL ||
447 *(authmethods[i]->enabled) == 0)
449 if (!auth2_method_allowed(authctxt, authmethods[i]->name,
452 if (buffer_len(&b) > 0)
453 buffer_append(&b, ",", 1);
454 buffer_append(&b, authmethods[i]->name,
455 strlen(authmethods[i]->name));
457 buffer_append(&b, "\0", 1);
458 list = xstrdup(buffer_ptr(&b));
464 authmethod_lookup(Authctxt *authctxt, const char *name)
469 for (i = 0; authmethods[i] != NULL; i++)
470 if (authmethods[i]->enabled != NULL &&
471 *(authmethods[i]->enabled) != 0 &&
472 strcmp(name, authmethods[i]->name) == 0 &&
473 auth2_method_allowed(authctxt,
474 authmethods[i]->name, NULL))
475 return authmethods[i];
476 debug2("Unrecognized authentication method name: %s",
477 name ? name : "NULL");
482 * Check a comma-separated list of methods for validity. Is need_enable is
483 * non-zero, then also require that the methods are enabled.
484 * Returns 0 on success or -1 if the methods list is invalid.
487 auth2_methods_valid(const char *_methods, int need_enable)
489 char *methods, *omethods, *method, *p;
493 if (*_methods == '\0') {
494 error("empty authentication method list");
497 omethods = methods = xstrdup(_methods);
498 while ((method = strsep(&methods, ",")) != NULL) {
499 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
500 if ((p = strchr(method, ':')) != NULL)
502 if (strcmp(method, authmethods[i]->name) != 0)
505 if (authmethods[i]->enabled == NULL ||
506 *(authmethods[i]->enabled) == 0) {
507 error("Disabled method \"%s\" in "
508 "AuthenticationMethods list \"%s\"",
517 error("Unknown authentication method \"%s\" in list",
529 * Prune the AuthenticationMethods supplied in the configuration, removing
530 * any methods lists that include disabled methods. Note that this might
531 * leave authctxt->num_auth_methods == 0, even when multiple required auth
532 * has been requested. For this reason, all tests for whether multiple is
533 * enabled should consult options.num_auth_methods directly.
536 auth2_setup_methods_lists(Authctxt *authctxt)
540 if (options.num_auth_methods == 0)
542 debug3("%s: checking methods", __func__);
543 authctxt->auth_methods = xcalloc(options.num_auth_methods,
544 sizeof(*authctxt->auth_methods));
545 authctxt->num_auth_methods = 0;
546 for (i = 0; i < options.num_auth_methods; i++) {
547 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
548 logit("Authentication methods list \"%s\" contains "
549 "disabled method, skipping",
550 options.auth_methods[i]);
553 debug("authentication methods list %d: %s",
554 authctxt->num_auth_methods, options.auth_methods[i]);
555 authctxt->auth_methods[authctxt->num_auth_methods++] =
556 xstrdup(options.auth_methods[i]);
558 if (authctxt->num_auth_methods == 0) {
559 error("No AuthenticationMethods left after eliminating "
567 list_starts_with(const char *methods, const char *method,
568 const char *submethod)
570 size_t l = strlen(method);
574 if (strncmp(methods, method, l) != 0)
577 match = MATCH_METHOD;
580 return MATCH_PARTIAL;
581 l = strlen(submethod);
583 if (strncmp(submethod, p, l))
588 if (*p != ',' && *p != '\0')
594 * Remove method from the start of a comma-separated list of methods.
595 * Returns 0 if the list of methods did not start with that method or 1
599 remove_method(char **methods, const char *method, const char *submethod)
601 char *omethods = *methods, *p;
602 size_t l = strlen(method);
605 match = list_starts_with(omethods, method, submethod);
606 if (match != MATCH_METHOD && match != MATCH_BOTH)
609 if (submethod && match == MATCH_BOTH)
610 p += 1 + strlen(submethod); /* include colon */
613 *methods = xstrdup(p);
619 * Called after successful authentication. Will remove the successful method
620 * from the start of each list in which it occurs. If it was the last method
621 * in any list, then authentication is deemed successful.
622 * Returns 1 if the method completed any authentication list or 0 otherwise.
625 auth2_update_methods_lists(Authctxt *authctxt, const char *method,
626 const char *submethod)
630 debug3("%s: updating methods list after \"%s\"", __func__, method);
631 for (i = 0; i < authctxt->num_auth_methods; i++) {
632 if (!remove_method(&(authctxt->auth_methods[i]), method,
636 if (*authctxt->auth_methods[i] == '\0') {
637 debug2("authentication methods list %d complete", i);
640 debug3("authentication methods list %d remaining: \"%s\"",
641 i, authctxt->auth_methods[i]);
643 /* This should not happen, but would be bad if it did */
645 fatal("%s: method not in AuthenticationMethods", __func__);