1 /* $OpenBSD: auth2.c,v 1.130 2014/01/29 06:18:35 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.
28 #include <sys/types.h>
50 #include "pathnames.h"
56 #include "monitor_wrap.h"
59 extern ServerOptions options;
60 extern u_char *session_id2;
61 extern u_int session_id2_len;
62 extern Buffer loginmsg;
66 extern Authmethod method_none;
67 extern Authmethod method_pubkey;
68 extern Authmethod method_passwd;
69 extern Authmethod method_kbdint;
70 extern Authmethod method_hostbased;
72 extern Authmethod method_gssapi;
75 Authmethod *authmethods[] = {
89 static void input_service_request(int, u_int32_t, void *);
90 static void input_userauth_request(int, u_int32_t, void *);
93 static Authmethod *authmethod_lookup(Authctxt *, const char *);
94 static char *authmethods_get(Authctxt *authctxt);
96 #define MATCH_NONE 0 /* method or submethod mismatch */
97 #define MATCH_METHOD 1 /* method matches (no submethod specified) */
98 #define MATCH_BOTH 2 /* method and submethod match */
99 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
100 static int list_starts_with(const char *, const char *, const char *);
103 auth2_read_banner(void)
110 if ((fd = open(options.banner, O_RDONLY)) == -1)
112 if (fstat(fd, &st) == -1) {
116 if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
121 len = (size_t)st.st_size; /* truncate */
122 banner = xmalloc(len + 1);
123 n = atomicio(read, fd, banner, len);
136 userauth_send_banner(const char *msg)
138 if (datafellows & SSH_BUG_BANNER)
141 packet_start(SSH2_MSG_USERAUTH_BANNER);
142 packet_put_cstring(msg);
143 packet_put_cstring(""); /* language, unused */
145 debug("%s: sent", __func__);
149 userauth_banner(void)
153 if (options.banner == NULL ||
154 strcasecmp(options.banner, "none") == 0 ||
155 (datafellows & SSH_BUG_BANNER) != 0)
158 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
160 userauth_send_banner(banner);
167 * loop until authctxt->success == TRUE
170 do_authentication2(Authctxt *authctxt)
172 dispatch_init(&dispatch_protocol_error);
173 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
174 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
179 input_service_request(int type, u_int32_t seq, void *ctxt)
181 Authctxt *authctxt = ctxt;
184 char *service = packet_get_cstring(&len);
187 if (authctxt == NULL)
188 fatal("input_service_request: no authctxt");
190 if (strcmp(service, "ssh-userauth") == 0) {
191 if (!authctxt->success) {
193 /* now we can handle user-auth requests */
194 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
197 /* XXX all other service requests are denied */
200 packet_start(SSH2_MSG_SERVICE_ACCEPT);
201 packet_put_cstring(service);
205 debug("bad service request %s", service);
206 packet_disconnect("bad service request %s", service);
213 input_userauth_request(int type, u_int32_t seq, void *ctxt)
215 Authctxt *authctxt = ctxt;
216 Authmethod *m = NULL;
217 char *user, *service, *method, *style = NULL;
218 int authenticated = 0;
220 if (authctxt == NULL)
221 fatal("input_userauth_request: no authctxt");
223 user = packet_get_cstring(NULL);
224 service = packet_get_cstring(NULL);
225 method = packet_get_cstring(NULL);
226 debug("userauth-request for user %s service %s method %s", user, service, method);
227 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
229 if ((style = strchr(user, ':')) != NULL)
232 if (authctxt->attempt++ == 0) {
233 /* setup auth context */
234 authctxt->pw = PRIVSEP(getpwnamallow(user));
235 authctxt->user = xstrdup(user);
236 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
238 debug2("input_userauth_request: setting up authctxt for %s", user);
240 logit("input_userauth_request: invalid user %s", user);
241 authctxt->pw = fakepw();
242 #ifdef SSH_AUDIT_EVENTS
243 PRIVSEP(audit_event(SSH_INVALID_USER));
248 PRIVSEP(start_pam(authctxt));
250 setproctitle("%s%s", authctxt->valid ? user : "unknown",
251 use_privsep ? " [net]" : "");
252 authctxt->service = xstrdup(service);
253 authctxt->style = style ? xstrdup(style) : NULL;
255 mm_inform_authserv(service, style);
257 if (auth2_setup_methods_lists(authctxt) != 0)
258 packet_disconnect("no authentication methods enabled");
259 } else if (strcmp(user, authctxt->user) != 0 ||
260 strcmp(service, authctxt->service) != 0) {
261 packet_disconnect("Change of username or service not allowed: "
262 "(%s,%s) -> (%s,%s)",
263 authctxt->user, authctxt->service, user, service);
266 auth2_challenge_stop(authctxt);
269 /* XXX move to auth2_gssapi_stop() */
270 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
271 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
274 authctxt->postponed = 0;
275 authctxt->server_caused_failure = 0;
277 /* try to authenticate user */
278 m = authmethod_lookup(authctxt, method);
279 if (m != NULL && authctxt->failures < options.max_authtries) {
280 debug2("input_userauth_request: try method %s", method);
281 authenticated = m->userauth(authctxt);
283 userauth_finish(authctxt, authenticated, method, NULL);
291 userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
292 const char *submethod)
297 if (!authctxt->valid && authenticated)
298 fatal("INTERNAL ERROR: authenticated invalid user %s",
300 if (authenticated && authctxt->postponed)
301 fatal("INTERNAL ERROR: authenticated and postponed");
303 /* Special handling for root */
304 if (authenticated && authctxt->pw->pw_uid == 0 &&
305 !auth_root_allowed(method)) {
307 #ifdef SSH_AUDIT_EVENTS
308 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
312 if (authenticated && options.num_auth_methods != 0) {
313 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
319 /* Log before sending the reply */
320 auth_log(authctxt, authenticated, partial, method, submethod);
322 if (authctxt->postponed)
326 if (options.use_pam && authenticated) {
327 if (!PRIVSEP(do_pam_account())) {
328 /* if PAM returned a message, send it to the user */
329 if (buffer_len(&loginmsg) > 0) {
330 buffer_append(&loginmsg, "\0", 1);
331 userauth_send_banner(buffer_ptr(&loginmsg));
334 fatal("Access denied for user %s by PAM account "
335 "configuration", authctxt->user);
341 if (authenticated && cray_access_denied(authctxt->user)) {
343 fatal("Access denied for user %s.", authctxt->user);
347 if (authenticated == 1) {
348 /* turn off userauth */
349 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
350 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
353 /* now we can break out */
354 authctxt->success = 1;
357 /* Allow initial try of "none" auth without failure penalty */
358 if (!authctxt->server_caused_failure &&
359 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
360 authctxt->failures++;
361 if (authctxt->failures >= options.max_authtries) {
362 #ifdef SSH_AUDIT_EVENTS
363 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
365 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
367 methods = authmethods_get(authctxt);
368 debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
370 packet_start(SSH2_MSG_USERAUTH_FAILURE);
371 packet_put_cstring(methods);
372 packet_put_char(partial);
380 * Checks whether method is allowed by at least one AuthenticationMethods
381 * methods list. Returns 1 if allowed, or no methods lists configured.
385 auth2_method_allowed(Authctxt *authctxt, const char *method,
386 const char *submethod)
391 * NB. authctxt->num_auth_methods might be zero as a result of
392 * auth2_setup_methods_lists(), so check the configuration.
394 if (options.num_auth_methods == 0)
396 for (i = 0; i < authctxt->num_auth_methods; i++) {
397 if (list_starts_with(authctxt->auth_methods[i], method,
398 submethod) != MATCH_NONE)
405 authmethods_get(Authctxt *authctxt)
412 for (i = 0; authmethods[i] != NULL; i++) {
413 if (strcmp(authmethods[i]->name, "none") == 0)
415 if (authmethods[i]->enabled == NULL ||
416 *(authmethods[i]->enabled) == 0)
418 if (!auth2_method_allowed(authctxt, authmethods[i]->name,
421 if (buffer_len(&b) > 0)
422 buffer_append(&b, ",", 1);
423 buffer_append(&b, authmethods[i]->name,
424 strlen(authmethods[i]->name));
426 buffer_append(&b, "\0", 1);
427 list = xstrdup(buffer_ptr(&b));
433 authmethod_lookup(Authctxt *authctxt, const char *name)
438 for (i = 0; authmethods[i] != NULL; i++)
439 if (authmethods[i]->enabled != NULL &&
440 *(authmethods[i]->enabled) != 0 &&
441 strcmp(name, authmethods[i]->name) == 0 &&
442 auth2_method_allowed(authctxt,
443 authmethods[i]->name, NULL))
444 return authmethods[i];
445 debug2("Unrecognized authentication method name: %s",
446 name ? name : "NULL");
451 * Check a comma-separated list of methods for validity. Is need_enable is
452 * non-zero, then also require that the methods are enabled.
453 * Returns 0 on success or -1 if the methods list is invalid.
456 auth2_methods_valid(const char *_methods, int need_enable)
458 char *methods, *omethods, *method, *p;
462 if (*_methods == '\0') {
463 error("empty authentication method list");
466 omethods = methods = xstrdup(_methods);
467 while ((method = strsep(&methods, ",")) != NULL) {
468 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
469 if ((p = strchr(method, ':')) != NULL)
471 if (strcmp(method, authmethods[i]->name) != 0)
474 if (authmethods[i]->enabled == NULL ||
475 *(authmethods[i]->enabled) == 0) {
476 error("Disabled method \"%s\" in "
477 "AuthenticationMethods list \"%s\"",
486 error("Unknown authentication method \"%s\" in list",
498 * Prune the AuthenticationMethods supplied in the configuration, removing
499 * any methods lists that include disabled methods. Note that this might
500 * leave authctxt->num_auth_methods == 0, even when multiple required auth
501 * has been requested. For this reason, all tests for whether multiple is
502 * enabled should consult options.num_auth_methods directly.
505 auth2_setup_methods_lists(Authctxt *authctxt)
509 if (options.num_auth_methods == 0)
511 debug3("%s: checking methods", __func__);
512 authctxt->auth_methods = xcalloc(options.num_auth_methods,
513 sizeof(*authctxt->auth_methods));
514 authctxt->num_auth_methods = 0;
515 for (i = 0; i < options.num_auth_methods; i++) {
516 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
517 logit("Authentication methods list \"%s\" contains "
518 "disabled method, skipping",
519 options.auth_methods[i]);
522 debug("authentication methods list %d: %s",
523 authctxt->num_auth_methods, options.auth_methods[i]);
524 authctxt->auth_methods[authctxt->num_auth_methods++] =
525 xstrdup(options.auth_methods[i]);
527 if (authctxt->num_auth_methods == 0) {
528 error("No AuthenticationMethods left after eliminating "
536 list_starts_with(const char *methods, const char *method,
537 const char *submethod)
539 size_t l = strlen(method);
543 if (strncmp(methods, method, l) != 0)
546 match = MATCH_METHOD;
549 return MATCH_PARTIAL;
550 l = strlen(submethod);
552 if (strncmp(submethod, p, l))
557 if (*p != ',' && *p != '\0')
563 * Remove method from the start of a comma-separated list of methods.
564 * Returns 0 if the list of methods did not start with that method or 1
568 remove_method(char **methods, const char *method, const char *submethod)
570 char *omethods = *methods, *p;
571 size_t l = strlen(method);
574 match = list_starts_with(omethods, method, submethod);
575 if (match != MATCH_METHOD && match != MATCH_BOTH)
578 if (submethod && match == MATCH_BOTH)
579 p += 1 + strlen(submethod); /* include colon */
582 *methods = xstrdup(p);
588 * Called after successful authentication. Will remove the successful method
589 * from the start of each list in which it occurs. If it was the last method
590 * in any list, then authentication is deemed successful.
591 * Returns 1 if the method completed any authentication list or 0 otherwise.
594 auth2_update_methods_lists(Authctxt *authctxt, const char *method,
595 const char *submethod)
599 debug3("%s: updating methods list after \"%s\"", __func__, method);
600 for (i = 0; i < authctxt->num_auth_methods; i++) {
601 if (!remove_method(&(authctxt->auth_methods[i]), method,
605 if (*authctxt->auth_methods[i] == '\0') {
606 debug2("authentication methods list %d complete", i);
609 debug3("authentication methods list %d remaining: \"%s\"",
610 i, authctxt->auth_methods[i]);
612 /* This should not happen, but would be bad if it did */
614 fatal("%s: method not in AuthenticationMethods", __func__);