1 /* $OpenBSD: auth2.c,v 1.126 2012/12/02 20:34:09 djm 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>
51 #include "pathnames.h"
58 #include "monitor_wrap.h"
61 extern ServerOptions options;
62 extern u_char *session_id2;
63 extern u_int session_id2_len;
64 extern Buffer loginmsg;
68 extern Authmethod method_none;
69 extern Authmethod method_pubkey;
70 extern Authmethod method_passwd;
71 extern Authmethod method_kbdint;
72 extern Authmethod method_hostbased;
74 extern Authmethod method_gssapi;
77 extern Authmethod method_jpake;
80 Authmethod *authmethods[] = {
97 static void input_service_request(int, u_int32_t, void *);
98 static void input_userauth_request(int, u_int32_t, void *);
101 static Authmethod *authmethod_lookup(Authctxt *, const char *);
102 static char *authmethods_get(Authctxt *authctxt);
103 static int method_allowed(Authctxt *, const char *);
104 static int list_starts_with(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 ||
158 strcasecmp(options.banner, "none") == 0 ||
159 (datafellows & SSH_BUG_BANNER) != 0)
162 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
164 userauth_send_banner(banner);
172 * loop until authctxt->success == TRUE
175 do_authentication2(Authctxt *authctxt)
177 dispatch_init(&dispatch_protocol_error);
178 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
179 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
184 input_service_request(int type, u_int32_t seq, void *ctxt)
186 Authctxt *authctxt = ctxt;
189 char *service = packet_get_cstring(&len);
192 if (authctxt == NULL)
193 fatal("input_service_request: no authctxt");
195 if (strcmp(service, "ssh-userauth") == 0) {
196 if (!authctxt->success) {
198 /* now we can handle user-auth requests */
199 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
202 /* XXX all other service requests are denied */
205 packet_start(SSH2_MSG_SERVICE_ACCEPT);
206 packet_put_cstring(service);
210 debug("bad service request %s", service);
211 packet_disconnect("bad service request %s", service);
218 input_userauth_request(int type, u_int32_t seq, void *ctxt)
220 Authctxt *authctxt = ctxt;
221 Authmethod *m = NULL;
222 char *user, *service, *method, *style = NULL;
223 int authenticated = 0;
224 #ifdef HAVE_LOGIN_CAP
226 const char *from_host, *from_ip;
228 from_host = get_canonical_hostname(options.use_dns);
229 from_ip = get_remote_ipaddr();
232 if (authctxt == NULL)
233 fatal("input_userauth_request: no authctxt");
235 user = packet_get_cstring(NULL);
236 service = packet_get_cstring(NULL);
237 method = packet_get_cstring(NULL);
238 debug("userauth-request for user %s service %s method %s", user, service, method);
239 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
241 if ((style = strchr(user, ':')) != NULL)
244 if (authctxt->attempt++ == 0) {
245 /* setup auth context */
246 authctxt->pw = PRIVSEP(getpwnamallow(user));
247 authctxt->user = xstrdup(user);
248 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
250 debug2("input_userauth_request: setting up authctxt for %s", user);
252 logit("input_userauth_request: invalid user %s", user);
253 authctxt->pw = fakepw();
254 #ifdef SSH_AUDIT_EVENTS
255 PRIVSEP(audit_event(SSH_INVALID_USER));
260 PRIVSEP(start_pam(authctxt));
262 setproctitle("%s%s", authctxt->valid ? user : "unknown",
263 use_privsep ? " [net]" : "");
264 authctxt->service = xstrdup(service);
265 authctxt->style = style ? xstrdup(style) : NULL;
267 mm_inform_authserv(service, style);
269 if (auth2_setup_methods_lists(authctxt) != 0)
270 packet_disconnect("no authentication methods enabled");
271 } else if (strcmp(user, authctxt->user) != 0 ||
272 strcmp(service, authctxt->service) != 0) {
273 packet_disconnect("Change of username or service not allowed: "
274 "(%s,%s) -> (%s,%s)",
275 authctxt->user, authctxt->service, user, service);
278 #ifdef HAVE_LOGIN_CAP
279 if (authctxt->pw != NULL) {
280 lc = login_getpwclass(authctxt->pw);
282 lc = login_getclassbyname(NULL, authctxt->pw);
283 if (!auth_hostok(lc, from_host, from_ip)) {
284 logit("Denied connection for %.200s from %.200s [%.200s].",
285 authctxt->pw->pw_name, from_host, from_ip);
286 packet_disconnect("Sorry, you are not allowed to connect.");
288 if (!auth_timeok(lc, time(NULL))) {
289 logit("LOGIN %.200s REFUSED (TIME) FROM %.200s",
290 authctxt->pw->pw_name, from_host);
291 packet_disconnect("Logins not available right now.");
296 #endif /* HAVE_LOGIN_CAP */
299 auth2_challenge_stop(authctxt);
301 auth2_jpake_stop(authctxt);
305 /* XXX move to auth2_gssapi_stop() */
306 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
307 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
310 authctxt->postponed = 0;
311 authctxt->server_caused_failure = 0;
313 /* try to authenticate user */
314 m = authmethod_lookup(authctxt, method);
315 if (m != NULL && authctxt->failures < options.max_authtries) {
316 debug2("input_userauth_request: try method %s", method);
317 authenticated = m->userauth(authctxt);
319 userauth_finish(authctxt, authenticated, method, NULL);
327 userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
328 const char *submethod)
333 if (!authctxt->valid && authenticated)
334 fatal("INTERNAL ERROR: authenticated invalid user %s",
336 if (authenticated && authctxt->postponed)
337 fatal("INTERNAL ERROR: authenticated and postponed");
339 /* Special handling for root */
340 if (authenticated && authctxt->pw->pw_uid == 0 &&
341 !auth_root_allowed(method)) {
343 #ifdef SSH_AUDIT_EVENTS
344 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
348 if (authenticated && options.num_auth_methods != 0) {
349 if (!auth2_update_methods_lists(authctxt, method)) {
355 /* Log before sending the reply */
356 auth_log(authctxt, authenticated, partial, method, submethod, " ssh2");
358 if (authctxt->postponed)
362 if (options.use_pam && authenticated) {
363 if (!PRIVSEP(do_pam_account())) {
364 /* if PAM returned a message, send it to the user */
365 if (buffer_len(&loginmsg) > 0) {
366 buffer_append(&loginmsg, "\0", 1);
367 userauth_send_banner(buffer_ptr(&loginmsg));
370 fatal("Access denied for user %s by PAM account "
371 "configuration", authctxt->user);
377 if (authenticated && cray_access_denied(authctxt->user)) {
379 fatal("Access denied for user %s.", authctxt->user);
383 if (authenticated == 1) {
384 /* turn off userauth */
385 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
386 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
389 /* now we can break out */
390 authctxt->success = 1;
393 /* Allow initial try of "none" auth without failure penalty */
394 if (!authctxt->server_caused_failure &&
395 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
396 authctxt->failures++;
397 if (authctxt->failures >= options.max_authtries) {
398 #ifdef SSH_AUDIT_EVENTS
399 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
401 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
403 methods = authmethods_get(authctxt);
404 debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
406 packet_start(SSH2_MSG_USERAUTH_FAILURE);
407 packet_put_cstring(methods);
408 packet_put_char(partial);
416 * Checks whether method is allowed by at least one AuthenticationMethods
417 * methods list. Returns 1 if allowed, or no methods lists configured.
421 method_allowed(Authctxt *authctxt, const char *method)
426 * NB. authctxt->num_auth_methods might be zero as a result of
427 * auth2_setup_methods_lists(), so check the configuration.
429 if (options.num_auth_methods == 0)
431 for (i = 0; i < authctxt->num_auth_methods; i++) {
432 if (list_starts_with(authctxt->auth_methods[i], method))
439 authmethods_get(Authctxt *authctxt)
446 for (i = 0; authmethods[i] != NULL; i++) {
447 if (strcmp(authmethods[i]->name, "none") == 0)
449 if (authmethods[i]->enabled == NULL ||
450 *(authmethods[i]->enabled) == 0)
452 if (!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 method_allowed(authctxt, authmethods[i]->name))
476 return authmethods[i];
477 debug2("Unrecognized authentication method name: %s",
478 name ? name : "NULL");
483 * Check a comma-separated list of methods for validity. Is need_enable is
484 * non-zero, then also require that the methods are enabled.
485 * Returns 0 on success or -1 if the methods list is invalid.
488 auth2_methods_valid(const char *_methods, int need_enable)
490 char *methods, *omethods, *method;
494 if (*_methods == '\0') {
495 error("empty authentication method list");
498 omethods = methods = xstrdup(_methods);
499 while ((method = strsep(&methods, ",")) != NULL) {
500 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
501 if (strcmp(method, authmethods[i]->name) != 0)
504 if (authmethods[i]->enabled == NULL ||
505 *(authmethods[i]->enabled) == 0) {
506 error("Disabled method \"%s\" in "
507 "AuthenticationMethods list \"%s\"",
516 error("Unknown authentication method \"%s\" in list",
528 * Prune the AuthenticationMethods supplied in the configuration, removing
529 * any methods lists that include disabled methods. Note that this might
530 * leave authctxt->num_auth_methods == 0, even when multiple required auth
531 * has been requested. For this reason, all tests for whether multiple is
532 * enabled should consult options.num_auth_methods directly.
535 auth2_setup_methods_lists(Authctxt *authctxt)
539 if (options.num_auth_methods == 0)
541 debug3("%s: checking methods", __func__);
542 authctxt->auth_methods = xcalloc(options.num_auth_methods,
543 sizeof(*authctxt->auth_methods));
544 authctxt->num_auth_methods = 0;
545 for (i = 0; i < options.num_auth_methods; i++) {
546 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
547 logit("Authentication methods list \"%s\" contains "
548 "disabled method, skipping",
549 options.auth_methods[i]);
552 debug("authentication methods list %d: %s",
553 authctxt->num_auth_methods, options.auth_methods[i]);
554 authctxt->auth_methods[authctxt->num_auth_methods++] =
555 xstrdup(options.auth_methods[i]);
557 if (authctxt->num_auth_methods == 0) {
558 error("No AuthenticationMethods left after eliminating "
566 list_starts_with(const char *methods, const char *method)
568 size_t l = strlen(method);
570 if (strncmp(methods, method, l) != 0)
572 if (methods[l] != ',' && methods[l] != '\0')
578 * Remove method from the start of a comma-separated list of methods.
579 * Returns 0 if the list of methods did not start with that method or 1
583 remove_method(char **methods, const char *method)
585 char *omethods = *methods;
586 size_t l = strlen(method);
588 if (!list_starts_with(omethods, method))
590 *methods = xstrdup(omethods + l + (omethods[l] == ',' ? 1 : 0));
596 * Called after successful authentication. Will remove the successful method
597 * from the start of each list in which it occurs. If it was the last method
598 * in any list, then authentication is deemed successful.
599 * Returns 1 if the method completed any authentication list or 0 otherwise.
602 auth2_update_methods_lists(Authctxt *authctxt, const char *method)
606 debug3("%s: updating methods list after \"%s\"", __func__, method);
607 for (i = 0; i < authctxt->num_auth_methods; i++) {
608 if (!remove_method(&(authctxt->auth_methods[i]), method))
611 if (*authctxt->auth_methods[i] == '\0') {
612 debug2("authentication methods list %d complete", i);
615 debug3("authentication methods list %d remaining: \"%s\"",
616 i, authctxt->auth_methods[i]);
618 /* This should not happen, but would be bad if it did */
620 fatal("%s: method not in AuthenticationMethods", __func__);