blob: 9108b8612bea215c3f22a7c275803e5760b922a4 [file] [log] [blame]
djm@openbsd.org1a31d022016-05-02 08:49:03 +00001/* $OpenBSD: auth2.c,v 1.136 2016/05/02 08:49:03 djm Exp $ */
Damien Millereba71ba2000-04-29 23:57:08 +10002/*
3 * Copyright (c) 2000 Markus Friedl. All rights reserved.
4 *
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.
Damien Millereba71ba2000-04-29 23:57:08 +100013 *
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.
24 */
Damien Millere4340be2000-09-16 13:29:08 +110025
Damien Millereba71ba2000-04-29 23:57:08 +100026#include "includes.h"
Damien Millereba71ba2000-04-29 23:57:08 +100027
Damien Miller9f2abc42006-07-10 20:53:08 +100028#include <sys/types.h>
Darren Tucker4230a5d2008-07-02 22:56:09 +100029#include <sys/stat.h>
30#include <sys/uio.h>
Damien Miller9f2abc42006-07-10 20:53:08 +100031
Darren Tucker4230a5d2008-07-02 22:56:09 +100032#include <fcntl.h>
Damien Miller9f2abc42006-07-10 20:53:08 +100033#include <pwd.h>
Damien Millerd7834352006-08-05 12:39:39 +100034#include <stdarg.h>
Damien Millere3476ed2006-07-24 14:13:33 +100035#include <string.h>
Darren Tucker4230a5d2008-07-02 22:56:09 +100036#include <unistd.h>
Damien Miller9f2abc42006-07-10 20:53:08 +100037
Damien Miller0b4d48b2008-07-05 09:44:53 +100038#include "atomicio.h"
Darren Tucker43e7a352009-06-21 19:50:08 +100039#include "xmalloc.h"
Damien Millerd7834352006-08-05 12:39:39 +100040#include "ssh2.h"
Damien Millereba71ba2000-04-29 23:57:08 +100041#include "packet.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000042#include "log.h"
Damien Millerd7834352006-08-05 12:39:39 +100043#include "buffer.h"
Damien Miller7acefbb2014-07-18 14:11:24 +100044#include "misc.h"
Damien Millereba71ba2000-04-29 23:57:08 +100045#include "servconf.h"
46#include "compat.h"
Damien Millerd7834352006-08-05 12:39:39 +100047#include "key.h"
48#include "hostfile.h"
Damien Millereba71ba2000-04-29 23:57:08 +100049#include "auth.h"
Damien Millereba71ba2000-04-29 23:57:08 +100050#include "dispatch.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000051#include "pathnames.h"
Darren Tucker77fc29e2004-09-11 23:07:03 +100052#include "buffer.h"
Damien Millereba71ba2000-04-29 23:57:08 +100053
Darren Tucker0efd1552003-08-26 11:49:55 +100054#ifdef GSSAPI
55#include "ssh-gss.h"
56#endif
Damien Millerd7834352006-08-05 12:39:39 +100057#include "monitor_wrap.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100058
Damien Millereba71ba2000-04-29 23:57:08 +100059/* import */
60extern ServerOptions options;
Ben Lindstrom46c16222000-12-22 01:43:59 +000061extern u_char *session_id2;
Darren Tucker502d3842003-06-28 12:38:01 +100062extern u_int session_id2_len;
Darren Tucker77fc29e2004-09-11 23:07:03 +100063extern Buffer loginmsg;
Damien Millereba71ba2000-04-29 23:57:08 +100064
Ben Lindstrom511bb242002-06-06 20:52:37 +000065/* methods */
66
67extern Authmethod method_none;
68extern Authmethod method_pubkey;
69extern Authmethod method_passwd;
70extern Authmethod method_kbdint;
71extern Authmethod method_hostbased;
Darren Tucker0efd1552003-08-26 11:49:55 +100072#ifdef GSSAPI
73extern Authmethod method_gssapi;
74#endif
Ben Lindstrom511bb242002-06-06 20:52:37 +000075
76Authmethod *authmethods[] = {
77 &method_none,
78 &method_pubkey,
Darren Tucker0efd1552003-08-26 11:49:55 +100079#ifdef GSSAPI
80 &method_gssapi,
81#endif
Ben Lindstrom511bb242002-06-06 20:52:37 +000082 &method_passwd,
83 &method_kbdint,
84 &method_hostbased,
85 NULL
Damien Miller874d77b2000-10-14 16:23:11 +110086};
87
Damien Millereba71ba2000-04-29 23:57:08 +100088/* protocol */
89
markus@openbsd.org3fdc88a2015-01-19 20:07:45 +000090static int input_service_request(int, u_int32_t, void *);
91static int input_userauth_request(int, u_int32_t, void *);
Damien Millereba71ba2000-04-29 23:57:08 +100092
Damien Millereba71ba2000-04-29 23:57:08 +100093/* helper */
Damien Millera6e3f012012-11-04 23:21:40 +110094static Authmethod *authmethod_lookup(Authctxt *, const char *);
95static char *authmethods_get(Authctxt *authctxt);
Damien Miller91a55f22013-04-23 15:18:10 +100096
97#define MATCH_NONE 0 /* method or submethod mismatch */
98#define MATCH_METHOD 1 /* method matches (no submethod specified) */
99#define MATCH_BOTH 2 /* method and submethod match */
100#define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
101static int list_starts_with(const char *, const char *, const char *);
Damien Millereba71ba2000-04-29 23:57:08 +1000102
Darren Tucker4230a5d2008-07-02 22:56:09 +1000103char *
104auth2_read_banner(void)
105{
106 struct stat st;
107 char *banner = NULL;
108 size_t len, n;
109 int fd;
110
111 if ((fd = open(options.banner, O_RDONLY)) == -1)
112 return (NULL);
113 if (fstat(fd, &st) == -1) {
114 close(fd);
115 return (NULL);
116 }
Damien Miller8ed4de82011-12-19 10:52:50 +1100117 if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
Darren Tucker4230a5d2008-07-02 22:56:09 +1000118 close(fd);
119 return (NULL);
120 }
121
122 len = (size_t)st.st_size; /* truncate */
123 banner = xmalloc(len + 1);
124 n = atomicio(read, fd, banner, len);
125 close(fd);
126
127 if (n != len) {
Darren Tuckera627d422013-06-02 07:31:17 +1000128 free(banner);
Darren Tucker4230a5d2008-07-02 22:56:09 +1000129 return (NULL);
130 }
131 banner[n] = '\0';
132
133 return (banner);
134}
135
136void
137userauth_send_banner(const char *msg)
138{
139 if (datafellows & SSH_BUG_BANNER)
140 return;
141
142 packet_start(SSH2_MSG_USERAUTH_BANNER);
143 packet_put_cstring(msg);
144 packet_put_cstring(""); /* language, unused */
145 packet_send();
146 debug("%s: sent", __func__);
147}
148
149static void
150userauth_banner(void)
151{
152 char *banner = NULL;
153
djm@openbsd.org161cf412014-12-22 07:55:51 +0000154 if (options.banner == NULL || (datafellows & SSH_BUG_BANNER) != 0)
Darren Tucker4230a5d2008-07-02 22:56:09 +1000155 return;
156
157 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
158 goto done;
159 userauth_send_banner(banner);
160
161done:
Darren Tuckera627d422013-06-02 07:31:17 +1000162 free(banner);
Darren Tucker4230a5d2008-07-02 22:56:09 +1000163}
164
Damien Millereba71ba2000-04-29 23:57:08 +1000165/*
Damien Miller874d77b2000-10-14 16:23:11 +1100166 * loop until authctxt->success == TRUE
Damien Millereba71ba2000-04-29 23:57:08 +1000167 */
Darren Tucker3e33cec2003-10-02 16:12:36 +1000168void
169do_authentication2(Authctxt *authctxt)
Damien Millereba71ba2000-04-29 23:57:08 +1000170{
Damien Miller7d053392002-01-22 23:24:13 +1100171 dispatch_init(&dispatch_protocol_error);
Damien Millereba71ba2000-04-29 23:57:08 +1000172 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
Damien Miller874d77b2000-10-14 16:23:11 +1100173 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
Damien Millereba71ba2000-04-29 23:57:08 +1000174}
175
Damien Miller91d4b122006-03-26 14:05:20 +1100176/*ARGSUSED*/
markus@openbsd.org3fdc88a2015-01-19 20:07:45 +0000177static int
Damien Miller630d6f42002-01-22 23:17:30 +1100178input_service_request(int type, u_int32_t seq, void *ctxt)
Damien Millereba71ba2000-04-29 23:57:08 +1000179{
Damien Miller874d77b2000-10-14 16:23:11 +1100180 Authctxt *authctxt = ctxt;
Ben Lindstrom46c16222000-12-22 01:43:59 +0000181 u_int len;
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000182 int acceptit = 0;
Damien Millerda108ec2010-08-31 22:36:39 +1000183 char *service = packet_get_cstring(&len);
Damien Miller48b03fc2002-01-22 23:11:40 +1100184 packet_check_eom();
Damien Millereba71ba2000-04-29 23:57:08 +1000185
Damien Miller874d77b2000-10-14 16:23:11 +1100186 if (authctxt == NULL)
187 fatal("input_service_request: no authctxt");
188
Damien Millereba71ba2000-04-29 23:57:08 +1000189 if (strcmp(service, "ssh-userauth") == 0) {
Damien Miller874d77b2000-10-14 16:23:11 +1100190 if (!authctxt->success) {
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000191 acceptit = 1;
Damien Millereba71ba2000-04-29 23:57:08 +1000192 /* now we can handle user-auth requests */
193 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
194 }
195 }
196 /* XXX all other service requests are denied */
197
Ben Lindstrom5a9d0ea2002-07-04 00:12:53 +0000198 if (acceptit) {
Damien Millereba71ba2000-04-29 23:57:08 +1000199 packet_start(SSH2_MSG_SERVICE_ACCEPT);
200 packet_put_cstring(service);
201 packet_send();
202 packet_write_wait();
203 } else {
204 debug("bad service request %s", service);
205 packet_disconnect("bad service request %s", service);
206 }
Darren Tuckera627d422013-06-02 07:31:17 +1000207 free(service);
markus@openbsd.org3fdc88a2015-01-19 20:07:45 +0000208 return 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000209}
210
Damien Miller91d4b122006-03-26 14:05:20 +1100211/*ARGSUSED*/
markus@openbsd.org3fdc88a2015-01-19 20:07:45 +0000212static int
Damien Miller630d6f42002-01-22 23:17:30 +1100213input_userauth_request(int type, u_int32_t seq, void *ctxt)
Damien Millereba71ba2000-04-29 23:57:08 +1000214{
Damien Miller874d77b2000-10-14 16:23:11 +1100215 Authctxt *authctxt = ctxt;
216 Authmethod *m = NULL;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000217 char *user, *service, *method, *style = NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000218 int authenticated = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000219
Damien Miller874d77b2000-10-14 16:23:11 +1100220 if (authctxt == NULL)
221 fatal("input_userauth_request: no authctxt");
Damien Millereba71ba2000-04-29 23:57:08 +1000222
Damien Millerda108ec2010-08-31 22:36:39 +1000223 user = packet_get_cstring(NULL);
224 service = packet_get_cstring(NULL);
225 method = packet_get_cstring(NULL);
Damien Miller874d77b2000-10-14 16:23:11 +1100226 debug("userauth-request for user %s service %s method %s", user, service, method);
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000227 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
Damien Miller874d77b2000-10-14 16:23:11 +1100228
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000229 if ((style = strchr(user, ':')) != NULL)
230 *style++ = 0;
231
Kevin Stevesef4eea92001-02-05 12:42:17 +0000232 if (authctxt->attempt++ == 0) {
Damien Miller3a5b0232002-03-13 13:19:42 +1100233 /* setup auth context */
Kevin Steves205cc1e2002-03-22 20:43:05 +0000234 authctxt->pw = PRIVSEP(getpwnamallow(user));
Darren Tuckerdbf7a742004-03-08 23:04:06 +1100235 authctxt->user = xstrdup(user);
Kevin Steves205cc1e2002-03-22 20:43:05 +0000236 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
Damien Miller874d77b2000-10-14 16:23:11 +1100237 authctxt->valid = 1;
238 debug2("input_userauth_request: setting up authctxt for %s", user);
Damien Miller874d77b2000-10-14 16:23:11 +1100239 } else {
Darren Tucker5cb30ad2004-08-12 22:40:24 +1000240 logit("input_userauth_request: invalid user %s", user);
Damien Miller856f0be2003-09-03 07:32:45 +1000241 authctxt->pw = fakepw();
Darren Tucker2e0cf0d2005-02-08 21:52:47 +1100242#ifdef SSH_AUDIT_EVENTS
243 PRIVSEP(audit_event(SSH_INVALID_USER));
Darren Tucker269a1ea2005-02-03 00:20:53 +1100244#endif
Damien Miller874d77b2000-10-14 16:23:11 +1100245 }
Darren Tuckerd3eff2b2005-09-24 12:43:51 +1000246#ifdef USE_PAM
247 if (options.use_pam)
248 PRIVSEP(start_pam(authctxt));
249#endif
Damien Miller30d1f842004-07-21 20:48:53 +1000250 setproctitle("%s%s", authctxt->valid ? user : "unknown",
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000251 use_privsep ? " [net]" : "");
Damien Miller874d77b2000-10-14 16:23:11 +1100252 authctxt->service = xstrdup(service);
Ben Lindstrom9d0c0662001-06-09 01:40:00 +0000253 authctxt->style = style ? xstrdup(style) : NULL;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000254 if (use_privsep)
255 mm_inform_authserv(service, style);
Darren Tucker4230a5d2008-07-02 22:56:09 +1000256 userauth_banner();
Damien Millera6e3f012012-11-04 23:21:40 +1100257 if (auth2_setup_methods_lists(authctxt) != 0)
258 packet_disconnect("no authentication methods enabled");
Ben Lindstrom9d0c0662001-06-09 01:40:00 +0000259 } 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);
Damien Millereba71ba2000-04-29 23:57:08 +1000264 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000265 /* reset state */
Damien Milleree116252001-12-21 12:42:34 +1100266 auth2_challenge_stop(authctxt);
Darren Tucker0efd1552003-08-26 11:49:55 +1000267
268#ifdef GSSAPI
Damien Miller01ed2272008-11-05 16:20:46 +1100269 /* XXX move to auth2_gssapi_stop() */
Darren Tucker0efd1552003-08-26 11:49:55 +1000270 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
271 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
272#endif
273
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000274 authctxt->postponed = 0;
Damien Miller3fcdfd52011-05-05 14:04:11 +1000275 authctxt->server_caused_failure = 0;
Damien Millerb70b61f2000-09-16 16:25:12 +1100276
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000277 /* try to authenticate user */
Damien Millera6e3f012012-11-04 23:21:40 +1100278 m = authmethod_lookup(authctxt, method);
Darren Tucker4230a5d2008-07-02 22:56:09 +1000279 if (m != NULL && authctxt->failures < options.max_authtries) {
Damien Miller874d77b2000-10-14 16:23:11 +1100280 debug2("input_userauth_request: try method %s", method);
281 authenticated = m->userauth(authctxt);
Damien Miller874d77b2000-10-14 16:23:11 +1100282 }
Damien Miller15b05cf2012-12-03 09:53:20 +1100283 userauth_finish(authctxt, authenticated, method, NULL);
Damien Miller5d57e502001-03-30 10:48:31 +1000284
Darren Tuckera627d422013-06-02 07:31:17 +1000285 free(service);
286 free(user);
287 free(method);
markus@openbsd.org3fdc88a2015-01-19 20:07:45 +0000288 return 0;
Damien Miller5d57e502001-03-30 10:48:31 +1000289}
290
291void
Damien Miller15b05cf2012-12-03 09:53:20 +1100292userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
293 const char *submethod)
Damien Miller5d57e502001-03-30 10:48:31 +1000294{
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000295 char *methods;
Damien Millera6e3f012012-11-04 23:21:40 +1100296 int partial = 0;
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000297
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000298 if (!authctxt->valid && authenticated)
299 fatal("INTERNAL ERROR: authenticated invalid user %s",
300 authctxt->user);
Damien Miller15b05cf2012-12-03 09:53:20 +1100301 if (authenticated && authctxt->postponed)
302 fatal("INTERNAL ERROR: authenticated and postponed");
Damien Millerb70b61f2000-09-16 16:25:12 +1100303
Damien Miller874d77b2000-10-14 16:23:11 +1100304 /* Special handling for root */
Damien Miller556f9312003-02-24 11:59:26 +1100305 if (authenticated && authctxt->pw->pw_uid == 0 &&
Darren Tucker269a1ea2005-02-03 00:20:53 +1100306 !auth_root_allowed(method)) {
Damien Millereba71ba2000-04-29 23:57:08 +1000307 authenticated = 0;
Darren Tucker2e0cf0d2005-02-08 21:52:47 +1100308#ifdef SSH_AUDIT_EVENTS
309 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
Darren Tucker269a1ea2005-02-03 00:20:53 +1100310#endif
311 }
Damien Millereba71ba2000-04-29 23:57:08 +1000312
Damien Miller15b05cf2012-12-03 09:53:20 +1100313 if (authenticated && options.num_auth_methods != 0) {
Damien Miller91a55f22013-04-23 15:18:10 +1000314 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
Damien Miller15b05cf2012-12-03 09:53:20 +1100315 authenticated = 0;
316 partial = 1;
317 }
318 }
319
320 /* Log before sending the reply */
Darren Tucker0acca372013-06-02 07:41:51 +1000321 auth_log(authctxt, authenticated, partial, method, submethod);
Damien Miller15b05cf2012-12-03 09:53:20 +1100322
323 if (authctxt->postponed)
324 return;
325
Damien Miller1f499fd2003-08-25 13:08:49 +1000326#ifdef USE_PAM
Darren Tucker77fc29e2004-09-11 23:07:03 +1000327 if (options.use_pam && authenticated) {
328 if (!PRIVSEP(do_pam_account())) {
Darren Tucker77fc29e2004-09-11 23:07:03 +1000329 /* if PAM returned a message, send it to the user */
330 if (buffer_len(&loginmsg) > 0) {
331 buffer_append(&loginmsg, "\0", 1);
332 userauth_send_banner(buffer_ptr(&loginmsg));
Darren Tuckerc1386672004-12-03 14:33:47 +1100333 packet_write_wait();
Darren Tucker77fc29e2004-09-11 23:07:03 +1000334 }
Darren Tuckerc1386672004-12-03 14:33:47 +1100335 fatal("Access denied for user %s by PAM account "
Damien Millerb6f72f52005-07-17 17:26:43 +1000336 "configuration", authctxt->user);
Darren Tucker77fc29e2004-09-11 23:07:03 +1000337 }
338 }
Damien Miller1f499fd2003-08-25 13:08:49 +1000339#endif
340
Tim Rice81ed5182002-09-25 17:38:46 -0700341#ifdef _UNICOS
342 if (authenticated && cray_access_denied(authctxt->user)) {
343 authenticated = 0;
Damien Miller15b05cf2012-12-03 09:53:20 +1100344 fatal("Access denied for user %s.", authctxt->user);
Tim Rice81ed5182002-09-25 17:38:46 -0700345 }
346#endif /* _UNICOS */
347
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000348 if (authenticated == 1) {
349 /* turn off userauth */
Damien Miller7d053392002-01-22 23:24:13 +1100350 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000351 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
352 packet_send();
353 packet_write_wait();
354 /* now we can break out */
355 authctxt->success = 1;
356 } else {
Damien Miller0b4d48b2008-07-05 09:44:53 +1000357
358 /* Allow initial try of "none" auth without failure penalty */
djm@openbsd.org058f8392014-12-18 23:58:04 +0000359 if (!partial && !authctxt->server_caused_failure &&
Damien Miller3fcdfd52011-05-05 14:04:11 +1000360 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
Damien Miller0b4d48b2008-07-05 09:44:53 +1000361 authctxt->failures++;
362 if (authctxt->failures >= options.max_authtries) {
Darren Tucker2e0cf0d2005-02-08 21:52:47 +1100363#ifdef SSH_AUDIT_EVENTS
364 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
Darren Tucker269a1ea2005-02-03 00:20:53 +1100365#endif
Damien Miller686feb52014-07-03 21:29:38 +1000366 auth_maxtries_exceeded(authctxt);
Darren Tucker269a1ea2005-02-03 00:20:53 +1100367 }
Damien Millera6e3f012012-11-04 23:21:40 +1100368 methods = authmethods_get(authctxt);
369 debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
370 partial, methods);
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000371 packet_start(SSH2_MSG_USERAUTH_FAILURE);
372 packet_put_cstring(methods);
Damien Millera6e3f012012-11-04 23:21:40 +1100373 packet_put_char(partial);
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000374 packet_send();
375 packet_write_wait();
Darren Tuckera627d422013-06-02 07:31:17 +1000376 free(methods);
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000377 }
Damien Miller874d77b2000-10-14 16:23:11 +1100378}
379
Damien Millera6e3f012012-11-04 23:21:40 +1100380/*
381 * Checks whether method is allowed by at least one AuthenticationMethods
382 * methods list. Returns 1 if allowed, or no methods lists configured.
383 * 0 otherwise.
384 */
Damien Miller91a55f22013-04-23 15:18:10 +1000385int
386auth2_method_allowed(Authctxt *authctxt, const char *method,
387 const char *submethod)
Damien Millera6e3f012012-11-04 23:21:40 +1100388{
389 u_int i;
390
391 /*
392 * NB. authctxt->num_auth_methods might be zero as a result of
393 * auth2_setup_methods_lists(), so check the configuration.
394 */
395 if (options.num_auth_methods == 0)
396 return 1;
397 for (i = 0; i < authctxt->num_auth_methods; i++) {
Damien Miller91a55f22013-04-23 15:18:10 +1000398 if (list_starts_with(authctxt->auth_methods[i], method,
399 submethod) != MATCH_NONE)
Damien Millera6e3f012012-11-04 23:21:40 +1100400 return 1;
401 }
402 return 0;
403}
404
Ben Lindstrom79073822001-07-04 03:42:30 +0000405static char *
Damien Millera6e3f012012-11-04 23:21:40 +1100406authmethods_get(Authctxt *authctxt)
Damien Miller874d77b2000-10-14 16:23:11 +1100407{
Damien Miller0e3b8722002-01-22 23:26:38 +1100408 Buffer b;
Damien Miller874d77b2000-10-14 16:23:11 +1100409 char *list;
Damien Millera6e3f012012-11-04 23:21:40 +1100410 u_int i;
Damien Miller874d77b2000-10-14 16:23:11 +1100411
Damien Miller0e3b8722002-01-22 23:26:38 +1100412 buffer_init(&b);
Ben Lindstrom511bb242002-06-06 20:52:37 +0000413 for (i = 0; authmethods[i] != NULL; i++) {
414 if (strcmp(authmethods[i]->name, "none") == 0)
Damien Miller874d77b2000-10-14 16:23:11 +1100415 continue;
Damien Millera6e3f012012-11-04 23:21:40 +1100416 if (authmethods[i]->enabled == NULL ||
417 *(authmethods[i]->enabled) == 0)
418 continue;
Damien Miller91a55f22013-04-23 15:18:10 +1000419 if (!auth2_method_allowed(authctxt, authmethods[i]->name,
420 NULL))
Damien Millera6e3f012012-11-04 23:21:40 +1100421 continue;
422 if (buffer_len(&b) > 0)
423 buffer_append(&b, ",", 1);
424 buffer_append(&b, authmethods[i]->name,
425 strlen(authmethods[i]->name));
Damien Millereba71ba2000-04-29 23:57:08 +1000426 }
djm@openbsd.org1a31d022016-05-02 08:49:03 +0000427 if ((list = sshbuf_dup_string(&b)) == NULL)
428 fatal("%s: sshbuf_dup_string failed", __func__);
Damien Miller0e3b8722002-01-22 23:26:38 +1100429 buffer_free(&b);
Damien Miller874d77b2000-10-14 16:23:11 +1100430 return list;
431}
432
Ben Lindstrombba81212001-06-25 05:01:22 +0000433static Authmethod *
Damien Millera6e3f012012-11-04 23:21:40 +1100434authmethod_lookup(Authctxt *authctxt, const char *name)
Damien Miller874d77b2000-10-14 16:23:11 +1100435{
Ben Lindstrom511bb242002-06-06 20:52:37 +0000436 int i;
437
Damien Miller874d77b2000-10-14 16:23:11 +1100438 if (name != NULL)
Ben Lindstrom511bb242002-06-06 20:52:37 +0000439 for (i = 0; authmethods[i] != NULL; i++)
440 if (authmethods[i]->enabled != NULL &&
441 *(authmethods[i]->enabled) != 0 &&
Damien Millera6e3f012012-11-04 23:21:40 +1100442 strcmp(name, authmethods[i]->name) == 0 &&
Damien Miller91a55f22013-04-23 15:18:10 +1000443 auth2_method_allowed(authctxt,
444 authmethods[i]->name, NULL))
Ben Lindstrom511bb242002-06-06 20:52:37 +0000445 return authmethods[i];
446 debug2("Unrecognized authentication method name: %s",
447 name ? name : "NULL");
Damien Miller874d77b2000-10-14 16:23:11 +1100448 return NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000449}
Darren Tucker4230a5d2008-07-02 22:56:09 +1000450
Damien Millera6e3f012012-11-04 23:21:40 +1100451/*
452 * Check a comma-separated list of methods for validity. Is need_enable is
453 * non-zero, then also require that the methods are enabled.
454 * Returns 0 on success or -1 if the methods list is invalid.
455 */
456int
457auth2_methods_valid(const char *_methods, int need_enable)
458{
Damien Miller91a55f22013-04-23 15:18:10 +1000459 char *methods, *omethods, *method, *p;
Damien Millera6e3f012012-11-04 23:21:40 +1100460 u_int i, found;
461 int ret = -1;
462
463 if (*_methods == '\0') {
464 error("empty authentication method list");
465 return -1;
466 }
467 omethods = methods = xstrdup(_methods);
468 while ((method = strsep(&methods, ",")) != NULL) {
469 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
Damien Miller91a55f22013-04-23 15:18:10 +1000470 if ((p = strchr(method, ':')) != NULL)
471 *p = '\0';
Damien Millera6e3f012012-11-04 23:21:40 +1100472 if (strcmp(method, authmethods[i]->name) != 0)
473 continue;
474 if (need_enable) {
475 if (authmethods[i]->enabled == NULL ||
476 *(authmethods[i]->enabled) == 0) {
477 error("Disabled method \"%s\" in "
478 "AuthenticationMethods list \"%s\"",
479 method, _methods);
480 goto out;
481 }
482 }
483 found = 1;
484 break;
485 }
486 if (!found) {
487 error("Unknown authentication method \"%s\" in list",
488 method);
489 goto out;
490 }
491 }
492 ret = 0;
493 out:
494 free(omethods);
495 return ret;
496}
497
498/*
499 * Prune the AuthenticationMethods supplied in the configuration, removing
500 * any methods lists that include disabled methods. Note that this might
501 * leave authctxt->num_auth_methods == 0, even when multiple required auth
502 * has been requested. For this reason, all tests for whether multiple is
503 * enabled should consult options.num_auth_methods directly.
504 */
505int
506auth2_setup_methods_lists(Authctxt *authctxt)
507{
508 u_int i;
509
510 if (options.num_auth_methods == 0)
511 return 0;
512 debug3("%s: checking methods", __func__);
513 authctxt->auth_methods = xcalloc(options.num_auth_methods,
514 sizeof(*authctxt->auth_methods));
515 authctxt->num_auth_methods = 0;
516 for (i = 0; i < options.num_auth_methods; i++) {
517 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
518 logit("Authentication methods list \"%s\" contains "
519 "disabled method, skipping",
520 options.auth_methods[i]);
521 continue;
522 }
523 debug("authentication methods list %d: %s",
524 authctxt->num_auth_methods, options.auth_methods[i]);
525 authctxt->auth_methods[authctxt->num_auth_methods++] =
526 xstrdup(options.auth_methods[i]);
527 }
528 if (authctxt->num_auth_methods == 0) {
529 error("No AuthenticationMethods left after eliminating "
530 "disabled methods");
531 return -1;
532 }
533 return 0;
534}
535
536static int
Damien Miller91a55f22013-04-23 15:18:10 +1000537list_starts_with(const char *methods, const char *method,
538 const char *submethod)
Damien Millera6e3f012012-11-04 23:21:40 +1100539{
540 size_t l = strlen(method);
Damien Miller91a55f22013-04-23 15:18:10 +1000541 int match;
542 const char *p;
Damien Millera6e3f012012-11-04 23:21:40 +1100543
544 if (strncmp(methods, method, l) != 0)
Damien Miller91a55f22013-04-23 15:18:10 +1000545 return MATCH_NONE;
546 p = methods + l;
547 match = MATCH_METHOD;
548 if (*p == ':') {
549 if (!submethod)
550 return MATCH_PARTIAL;
551 l = strlen(submethod);
552 p += 1;
553 if (strncmp(submethod, p, l))
554 return MATCH_NONE;
555 p += l;
556 match = MATCH_BOTH;
557 }
558 if (*p != ',' && *p != '\0')
559 return MATCH_NONE;
560 return match;
Damien Millera6e3f012012-11-04 23:21:40 +1100561}
562
563/*
564 * Remove method from the start of a comma-separated list of methods.
565 * Returns 0 if the list of methods did not start with that method or 1
566 * if it did.
567 */
568static int
Damien Miller91a55f22013-04-23 15:18:10 +1000569remove_method(char **methods, const char *method, const char *submethod)
Damien Millera6e3f012012-11-04 23:21:40 +1100570{
Damien Miller91a55f22013-04-23 15:18:10 +1000571 char *omethods = *methods, *p;
Damien Millera6e3f012012-11-04 23:21:40 +1100572 size_t l = strlen(method);
Damien Miller91a55f22013-04-23 15:18:10 +1000573 int match;
Damien Millera6e3f012012-11-04 23:21:40 +1100574
Damien Miller91a55f22013-04-23 15:18:10 +1000575 match = list_starts_with(omethods, method, submethod);
576 if (match != MATCH_METHOD && match != MATCH_BOTH)
Damien Millera6e3f012012-11-04 23:21:40 +1100577 return 0;
Damien Miller91a55f22013-04-23 15:18:10 +1000578 p = omethods + l;
579 if (submethod && match == MATCH_BOTH)
580 p += 1 + strlen(submethod); /* include colon */
581 if (*p == ',')
582 p++;
583 *methods = xstrdup(p);
Damien Millera6e3f012012-11-04 23:21:40 +1100584 free(omethods);
585 return 1;
586}
587
588/*
589 * Called after successful authentication. Will remove the successful method
590 * from the start of each list in which it occurs. If it was the last method
591 * in any list, then authentication is deemed successful.
592 * Returns 1 if the method completed any authentication list or 0 otherwise.
593 */
594int
Damien Miller91a55f22013-04-23 15:18:10 +1000595auth2_update_methods_lists(Authctxt *authctxt, const char *method,
596 const char *submethod)
Damien Millera6e3f012012-11-04 23:21:40 +1100597{
598 u_int i, found = 0;
599
600 debug3("%s: updating methods list after \"%s\"", __func__, method);
601 for (i = 0; i < authctxt->num_auth_methods; i++) {
Damien Miller91a55f22013-04-23 15:18:10 +1000602 if (!remove_method(&(authctxt->auth_methods[i]), method,
603 submethod))
Damien Millera6e3f012012-11-04 23:21:40 +1100604 continue;
605 found = 1;
606 if (*authctxt->auth_methods[i] == '\0') {
607 debug2("authentication methods list %d complete", i);
608 return 1;
609 }
610 debug3("authentication methods list %d remaining: \"%s\"",
611 i, authctxt->auth_methods[i]);
612 }
613 /* This should not happen, but would be bad if it did */
614 if (!found)
615 fatal("%s: method not in AuthenticationMethods", __func__);
616 return 0;
617}
618
619