kernel - Reduce stalls, refactor lwkt_switch() core.
[dragonfly.git] / crypto / openssh / auth2.c
blob6d34566822e734e5992742f93c7c693d7d529454
1 /* $OpenBSD: auth2.c,v 1.132 2014/07/15 15:54:14 millert Exp $ */
2 /*
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
7 * are met:
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.
26 #include "includes.h"
28 #include <sys/types.h>
29 #include <sys/stat.h>
30 #include <sys/uio.h>
32 #include <fcntl.h>
33 #include <pwd.h>
34 #include <stdarg.h>
35 #include <string.h>
36 #include <unistd.h>
38 #include "atomicio.h"
39 #include "xmalloc.h"
40 #include "ssh2.h"
41 #include "packet.h"
42 #include "log.h"
43 #include "buffer.h"
44 #include "misc.h"
45 #include "servconf.h"
46 #include "compat.h"
47 #include "key.h"
48 #include "hostfile.h"
49 #include "auth.h"
50 #include "dispatch.h"
51 #include "pathnames.h"
52 #include "buffer.h"
53 #include "canohost.h"
55 #ifdef GSSAPI
56 #include "ssh-gss.h"
57 #endif
58 #include "monitor_wrap.h"
60 /* import */
61 extern ServerOptions options;
62 extern u_char *session_id2;
63 extern u_int session_id2_len;
64 extern Buffer loginmsg;
66 /* methods */
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;
73 #ifdef GSSAPI
74 extern Authmethod method_gssapi;
75 #endif
77 static int log_flag = 0;
80 Authmethod *authmethods[] = {
81 &method_none,
82 &method_pubkey,
83 #ifdef GSSAPI
84 &method_gssapi,
85 #endif
86 &method_passwd,
87 &method_kbdint,
88 &method_hostbased,
89 NULL
92 /* protocol */
94 static void input_service_request(int, u_int32_t, void *);
95 static void input_userauth_request(int, u_int32_t, void *);
97 /* helper */
98 static Authmethod *authmethod_lookup(Authctxt *, const char *);
99 static char *authmethods_get(Authctxt *authctxt);
101 #define MATCH_NONE 0 /* method or submethod mismatch */
102 #define MATCH_METHOD 1 /* method matches (no submethod specified) */
103 #define MATCH_BOTH 2 /* method and submethod match */
104 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
105 static int list_starts_with(const char *, const char *, const char *);
107 char *
108 auth2_read_banner(void)
110 struct stat st;
111 char *banner = NULL;
112 size_t len, n;
113 int fd;
115 if ((fd = open(options.banner, O_RDONLY)) == -1)
116 return (NULL);
117 if (fstat(fd, &st) == -1) {
118 close(fd);
119 return (NULL);
121 if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
122 close(fd);
123 return (NULL);
126 len = (size_t)st.st_size; /* truncate */
127 banner = xmalloc(len + 1);
128 n = atomicio(read, fd, banner, len);
129 close(fd);
131 if (n != len) {
132 free(banner);
133 return (NULL);
135 banner[n] = '\0';
137 return (banner);
140 void
141 userauth_send_banner(const char *msg)
143 if (datafellows & SSH_BUG_BANNER)
144 return;
146 packet_start(SSH2_MSG_USERAUTH_BANNER);
147 packet_put_cstring(msg);
148 packet_put_cstring(""); /* language, unused */
149 packet_send();
150 debug("%s: sent", __func__);
153 static void
154 userauth_banner(void)
156 char *banner = NULL;
158 if (options.banner == NULL ||
159 strcasecmp(options.banner, "none") == 0 ||
160 (datafellows & SSH_BUG_BANNER) != 0)
161 return;
163 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
164 goto done;
165 userauth_send_banner(banner);
167 done:
168 free(banner);
172 * loop until authctxt->success == TRUE
174 void
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);
182 /*ARGSUSED*/
183 static void
184 input_service_request(int type, u_int32_t seq, void *ctxt)
186 Authctxt *authctxt = ctxt;
187 u_int len;
188 int acceptit = 0;
189 char *service = packet_get_cstring(&len);
190 packet_check_eom();
192 if (authctxt == NULL)
193 fatal("input_service_request: no authctxt");
195 if (strcmp(service, "ssh-userauth") == 0) {
196 if (!authctxt->success) {
197 acceptit = 1;
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 */
204 if (acceptit) {
205 packet_start(SSH2_MSG_SERVICE_ACCEPT);
206 packet_put_cstring(service);
207 packet_send();
208 packet_write_wait();
209 } else {
210 debug("bad service request %s", service);
211 packet_disconnect("bad service request %s", service);
213 free(service);
216 /*ARGSUSED*/
217 static void
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
225 login_cap_t *lc;
226 const char *from_host, *from_ip;
228 from_host = get_canonical_hostname(options.use_dns);
229 from_ip = get_remote_ipaddr();
230 #endif
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 if (!log_flag) {
240 logit("SSH: Server;Ltype: Authname;Remote: %s-%d;Name: %s",
241 get_remote_ipaddr(), get_remote_port(), user);
242 log_flag = 1;
244 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
246 if ((style = strchr(user, ':')) != NULL)
247 *style++ = 0;
249 if (authctxt->attempt++ == 0) {
250 /* setup auth context */
251 authctxt->pw = PRIVSEP(getpwnamallow(user));
252 authctxt->user = xstrdup(user);
253 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
254 authctxt->valid = 1;
255 debug2("input_userauth_request: setting up authctxt for %s", user);
256 } else {
257 logit("input_userauth_request: invalid user %s", user);
258 authctxt->pw = fakepw();
259 #ifdef SSH_AUDIT_EVENTS
260 PRIVSEP(audit_event(SSH_INVALID_USER));
261 #endif
263 #ifdef USE_PAM
264 if (options.use_pam)
265 PRIVSEP(start_pam(authctxt));
266 #endif
267 setproctitle("%s%s", authctxt->valid ? user : "unknown",
268 use_privsep ? " [net]" : "");
269 authctxt->service = xstrdup(service);
270 authctxt->style = style ? xstrdup(style) : NULL;
271 if (use_privsep)
272 mm_inform_authserv(service, style);
273 userauth_banner();
274 if (auth2_setup_methods_lists(authctxt) != 0)
275 packet_disconnect("no authentication methods enabled");
276 } else if (strcmp(user, authctxt->user) != 0 ||
277 strcmp(service, authctxt->service) != 0) {
278 packet_disconnect("Change of username or service not allowed: "
279 "(%s,%s) -> (%s,%s)",
280 authctxt->user, authctxt->service, user, service);
283 #ifdef HAVE_LOGIN_CAP
284 if (authctxt->pw != NULL) {
285 lc = login_getpwclass(authctxt->pw);
286 if (lc == NULL)
287 lc = login_getclassbyname(NULL, authctxt->pw);
288 if (!auth_hostok(lc, from_host, from_ip)) {
289 logit("Denied connection for %.200s from %.200s [%.200s].",
290 authctxt->pw->pw_name, from_host, from_ip);
291 packet_disconnect("Sorry, you are not allowed to connect.");
293 if (!auth_timeok(lc, time(NULL))) {
294 logit("LOGIN %.200s REFUSED (TIME) FROM %.200s",
295 authctxt->pw->pw_name, from_host);
296 packet_disconnect("Logins not available right now.");
298 login_close(lc);
299 lc = NULL;
301 #endif /* HAVE_LOGIN_CAP */
303 /* reset state */
304 auth2_challenge_stop(authctxt);
306 #ifdef GSSAPI
307 /* XXX move to auth2_gssapi_stop() */
308 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
309 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
310 #endif
312 authctxt->postponed = 0;
313 authctxt->server_caused_failure = 0;
315 /* try to authenticate user */
316 m = authmethod_lookup(authctxt, method);
317 if (m != NULL && authctxt->failures < options.max_authtries) {
318 debug2("input_userauth_request: try method %s", method);
319 authenticated = m->userauth(authctxt);
321 userauth_finish(authctxt, authenticated, method, NULL);
323 free(service);
324 free(user);
325 free(method);
328 void
329 userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
330 const char *submethod)
332 char *methods;
333 int partial = 0;
335 if (!authctxt->valid && authenticated)
336 fatal("INTERNAL ERROR: authenticated invalid user %s",
337 authctxt->user);
338 if (authenticated && authctxt->postponed)
339 fatal("INTERNAL ERROR: authenticated and postponed");
341 /* Special handling for root */
342 if (authenticated && authctxt->pw->pw_uid == 0 &&
343 !auth_root_allowed(method)) {
344 authenticated = 0;
345 #ifdef SSH_AUDIT_EVENTS
346 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
347 #endif
350 if (authenticated && options.num_auth_methods != 0) {
351 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
352 authenticated = 0;
353 partial = 1;
357 /* Log before sending the reply */
358 auth_log(authctxt, authenticated, partial, method, submethod);
360 if (authctxt->postponed)
361 return;
363 #ifdef USE_PAM
364 if (options.use_pam && authenticated) {
365 if (!PRIVSEP(do_pam_account())) {
366 /* if PAM returned a message, send it to the user */
367 if (buffer_len(&loginmsg) > 0) {
368 buffer_append(&loginmsg, "\0", 1);
369 userauth_send_banner(buffer_ptr(&loginmsg));
370 packet_write_wait();
372 fatal("Access denied for user %s by PAM account "
373 "configuration", authctxt->user);
376 #endif
378 #ifdef _UNICOS
379 if (authenticated && cray_access_denied(authctxt->user)) {
380 authenticated = 0;
381 fatal("Access denied for user %s.", authctxt->user);
383 #endif /* _UNICOS */
385 if (authenticated == 1) {
386 /* turn off userauth */
387 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
388 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
389 packet_send();
390 packet_write_wait();
391 /* now we can break out */
392 authctxt->success = 1;
393 } else {
395 /* Allow initial try of "none" auth without failure penalty */
396 if (!authctxt->server_caused_failure &&
397 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
398 authctxt->failures++;
399 if (authctxt->failures >= options.max_authtries) {
400 #ifdef SSH_AUDIT_EVENTS
401 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
402 #endif
403 auth_maxtries_exceeded(authctxt);
405 methods = authmethods_get(authctxt);
406 debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
407 partial, methods);
408 packet_start(SSH2_MSG_USERAUTH_FAILURE);
409 packet_put_cstring(methods);
410 packet_put_char(partial);
411 packet_send();
412 packet_write_wait();
413 free(methods);
418 * Checks whether method is allowed by at least one AuthenticationMethods
419 * methods list. Returns 1 if allowed, or no methods lists configured.
420 * 0 otherwise.
423 auth2_method_allowed(Authctxt *authctxt, const char *method,
424 const char *submethod)
426 u_int i;
429 * NB. authctxt->num_auth_methods might be zero as a result of
430 * auth2_setup_methods_lists(), so check the configuration.
432 if (options.num_auth_methods == 0)
433 return 1;
434 for (i = 0; i < authctxt->num_auth_methods; i++) {
435 if (list_starts_with(authctxt->auth_methods[i], method,
436 submethod) != MATCH_NONE)
437 return 1;
439 return 0;
442 static char *
443 authmethods_get(Authctxt *authctxt)
445 Buffer b;
446 char *list;
447 u_int i;
449 buffer_init(&b);
450 for (i = 0; authmethods[i] != NULL; i++) {
451 if (strcmp(authmethods[i]->name, "none") == 0)
452 continue;
453 if (authmethods[i]->enabled == NULL ||
454 *(authmethods[i]->enabled) == 0)
455 continue;
456 if (!auth2_method_allowed(authctxt, authmethods[i]->name,
457 NULL))
458 continue;
459 if (buffer_len(&b) > 0)
460 buffer_append(&b, ",", 1);
461 buffer_append(&b, authmethods[i]->name,
462 strlen(authmethods[i]->name));
464 buffer_append(&b, "\0", 1);
465 list = xstrdup(buffer_ptr(&b));
466 buffer_free(&b);
467 return list;
470 static Authmethod *
471 authmethod_lookup(Authctxt *authctxt, const char *name)
473 int i;
475 if (name != NULL)
476 for (i = 0; authmethods[i] != NULL; i++)
477 if (authmethods[i]->enabled != NULL &&
478 *(authmethods[i]->enabled) != 0 &&
479 strcmp(name, authmethods[i]->name) == 0 &&
480 auth2_method_allowed(authctxt,
481 authmethods[i]->name, NULL))
482 return authmethods[i];
483 debug2("Unrecognized authentication method name: %s",
484 name ? name : "NULL");
485 return NULL;
489 * Check a comma-separated list of methods for validity. Is need_enable is
490 * non-zero, then also require that the methods are enabled.
491 * Returns 0 on success or -1 if the methods list is invalid.
494 auth2_methods_valid(const char *_methods, int need_enable)
496 char *methods, *omethods, *method, *p;
497 u_int i, found;
498 int ret = -1;
500 if (*_methods == '\0') {
501 error("empty authentication method list");
502 return -1;
504 omethods = methods = xstrdup(_methods);
505 while ((method = strsep(&methods, ",")) != NULL) {
506 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
507 if ((p = strchr(method, ':')) != NULL)
508 *p = '\0';
509 if (strcmp(method, authmethods[i]->name) != 0)
510 continue;
511 if (need_enable) {
512 if (authmethods[i]->enabled == NULL ||
513 *(authmethods[i]->enabled) == 0) {
514 error("Disabled method \"%s\" in "
515 "AuthenticationMethods list \"%s\"",
516 method, _methods);
517 goto out;
520 found = 1;
521 break;
523 if (!found) {
524 error("Unknown authentication method \"%s\" in list",
525 method);
526 goto out;
529 ret = 0;
530 out:
531 free(omethods);
532 return ret;
536 * Prune the AuthenticationMethods supplied in the configuration, removing
537 * any methods lists that include disabled methods. Note that this might
538 * leave authctxt->num_auth_methods == 0, even when multiple required auth
539 * has been requested. For this reason, all tests for whether multiple is
540 * enabled should consult options.num_auth_methods directly.
543 auth2_setup_methods_lists(Authctxt *authctxt)
545 u_int i;
547 if (options.num_auth_methods == 0)
548 return 0;
549 debug3("%s: checking methods", __func__);
550 authctxt->auth_methods = xcalloc(options.num_auth_methods,
551 sizeof(*authctxt->auth_methods));
552 authctxt->num_auth_methods = 0;
553 for (i = 0; i < options.num_auth_methods; i++) {
554 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
555 logit("Authentication methods list \"%s\" contains "
556 "disabled method, skipping",
557 options.auth_methods[i]);
558 continue;
560 debug("authentication methods list %d: %s",
561 authctxt->num_auth_methods, options.auth_methods[i]);
562 authctxt->auth_methods[authctxt->num_auth_methods++] =
563 xstrdup(options.auth_methods[i]);
565 if (authctxt->num_auth_methods == 0) {
566 error("No AuthenticationMethods left after eliminating "
567 "disabled methods");
568 return -1;
570 return 0;
573 static int
574 list_starts_with(const char *methods, const char *method,
575 const char *submethod)
577 size_t l = strlen(method);
578 int match;
579 const char *p;
581 if (strncmp(methods, method, l) != 0)
582 return MATCH_NONE;
583 p = methods + l;
584 match = MATCH_METHOD;
585 if (*p == ':') {
586 if (!submethod)
587 return MATCH_PARTIAL;
588 l = strlen(submethod);
589 p += 1;
590 if (strncmp(submethod, p, l))
591 return MATCH_NONE;
592 p += l;
593 match = MATCH_BOTH;
595 if (*p != ',' && *p != '\0')
596 return MATCH_NONE;
597 return match;
601 * Remove method from the start of a comma-separated list of methods.
602 * Returns 0 if the list of methods did not start with that method or 1
603 * if it did.
605 static int
606 remove_method(char **methods, const char *method, const char *submethod)
608 char *omethods = *methods, *p;
609 size_t l = strlen(method);
610 int match;
612 match = list_starts_with(omethods, method, submethod);
613 if (match != MATCH_METHOD && match != MATCH_BOTH)
614 return 0;
615 p = omethods + l;
616 if (submethod && match == MATCH_BOTH)
617 p += 1 + strlen(submethod); /* include colon */
618 if (*p == ',')
619 p++;
620 *methods = xstrdup(p);
621 free(omethods);
622 return 1;
626 * Called after successful authentication. Will remove the successful method
627 * from the start of each list in which it occurs. If it was the last method
628 * in any list, then authentication is deemed successful.
629 * Returns 1 if the method completed any authentication list or 0 otherwise.
632 auth2_update_methods_lists(Authctxt *authctxt, const char *method,
633 const char *submethod)
635 u_int i, found = 0;
637 debug3("%s: updating methods list after \"%s\"", __func__, method);
638 for (i = 0; i < authctxt->num_auth_methods; i++) {
639 if (!remove_method(&(authctxt->auth_methods[i]), method,
640 submethod))
641 continue;
642 found = 1;
643 if (*authctxt->auth_methods[i] == '\0') {
644 debug2("authentication methods list %d complete", i);
645 return 1;
647 debug3("authentication methods list %d remaining: \"%s\"",
648 i, authctxt->auth_methods[i]);
650 /* This should not happen, but would be bad if it did */
651 if (!found)
652 fatal("%s: method not in AuthenticationMethods", __func__);
653 return 0;