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Damien Millereba71ba2000-04-29 23:57:08 +10001/*
2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
Damien Millereba71ba2000-04-29 23:57:08 +100012 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
Damien Millere4340be2000-09-16 13:29:08 +110024
Damien Millereba71ba2000-04-29 23:57:08 +100025#include "includes.h"
Ben Lindstrom511bb242002-06-06 20:52:37 +000026RCSID("$OpenBSD: auth2.c,v 1.93 2002/05/31 11:35:15 markus Exp $");
Damien Millereba71ba2000-04-29 23:57:08 +100027
Ben Lindstrom226cfa02001-01-22 05:34:40 +000028#include "ssh2.h"
Damien Millereba71ba2000-04-29 23:57:08 +100029#include "xmalloc.h"
Damien Millereba71ba2000-04-29 23:57:08 +100030#include "packet.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000031#include "log.h"
Damien Millereba71ba2000-04-29 23:57:08 +100032#include "servconf.h"
33#include "compat.h"
Damien Millereba71ba2000-04-29 23:57:08 +100034#include "auth.h"
Damien Millereba71ba2000-04-29 23:57:08 +100035#include "dispatch.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000036#include "pathnames.h"
Ben Lindstrom7a2073c2002-03-22 02:30:41 +000037#include "monitor_wrap.h"
Damien Millereba71ba2000-04-29 23:57:08 +100038
39/* import */
40extern ServerOptions options;
Ben Lindstrom46c16222000-12-22 01:43:59 +000041extern u_char *session_id2;
Damien Millereba71ba2000-04-29 23:57:08 +100042extern int session_id2_len;
43
Ben Lindstrom7a2073c2002-03-22 02:30:41 +000044Authctxt *x_authctxt = NULL;
Damien Miller874d77b2000-10-14 16:23:11 +110045
Ben Lindstrom511bb242002-06-06 20:52:37 +000046/* methods */
47
48extern Authmethod method_none;
49extern Authmethod method_pubkey;
50extern Authmethod method_passwd;
51extern Authmethod method_kbdint;
52extern Authmethod method_hostbased;
53
54Authmethod *authmethods[] = {
55 &method_none,
56 &method_pubkey,
57 &method_passwd,
58 &method_kbdint,
59 &method_hostbased,
60 NULL
Damien Miller874d77b2000-10-14 16:23:11 +110061};
62
Damien Millereba71ba2000-04-29 23:57:08 +100063/* protocol */
64
Damien Miller630d6f42002-01-22 23:17:30 +110065static void input_service_request(int, u_int32_t, void *);
66static void input_userauth_request(int, u_int32_t, void *);
Damien Millereba71ba2000-04-29 23:57:08 +100067
Damien Millereba71ba2000-04-29 23:57:08 +100068/* helper */
Ben Lindstrombba81212001-06-25 05:01:22 +000069static Authmethod *authmethod_lookup(const char *);
Ben Lindstrom79073822001-07-04 03:42:30 +000070static char *authmethods_get(void);
Ben Lindstrom7a2073c2002-03-22 02:30:41 +000071int user_key_allowed(struct passwd *, Key *);
72int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
Damien Millereba71ba2000-04-29 23:57:08 +100073
Damien Millereba71ba2000-04-29 23:57:08 +100074/*
Damien Miller874d77b2000-10-14 16:23:11 +110075 * loop until authctxt->success == TRUE
Damien Millereba71ba2000-04-29 23:57:08 +100076 */
77
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +000078Authctxt *
Ben Lindstrom3c36bb22001-12-06 17:55:26 +000079do_authentication2(void)
Damien Millereba71ba2000-04-29 23:57:08 +100080{
Ben Lindstromdb65e8f2001-01-19 04:26:52 +000081 Authctxt *authctxt = authctxt_new();
82
Damien Miller874d77b2000-10-14 16:23:11 +110083 x_authctxt = authctxt; /*XXX*/
84
Ben Lindstrombdfb4df2001-10-03 17:12:43 +000085 /* challenge-response is implemented via keyboard interactive */
Ben Lindstrom551ea372001-06-05 18:56:16 +000086 if (options.challenge_response_authentication)
Ben Lindstrom95fb2dd2001-01-23 03:12:10 +000087 options.kbd_interactive_authentication = 1;
Damien Millerf8154422001-04-25 22:44:14 +100088 if (options.pam_authentication_via_kbd_int)
89 options.kbd_interactive_authentication = 1;
Damien Millerffc868f2002-05-09 15:59:13 +100090 if (use_privsep)
91 options.pam_authentication_via_kbd_int = 0;
Ben Lindstrom95fb2dd2001-01-23 03:12:10 +000092
Damien Miller7d053392002-01-22 23:24:13 +110093 dispatch_init(&dispatch_protocol_error);
Damien Millereba71ba2000-04-29 23:57:08 +100094 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
Damien Miller874d77b2000-10-14 16:23:11 +110095 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
Ben Lindstrom73ab9ba2002-03-22 01:27:35 +000096
97 return (authctxt);
Damien Millereba71ba2000-04-29 23:57:08 +100098}
99
Ben Lindstrombba81212001-06-25 05:01:22 +0000100static void
Damien Miller630d6f42002-01-22 23:17:30 +1100101input_service_request(int type, u_int32_t seq, void *ctxt)
Damien Millereba71ba2000-04-29 23:57:08 +1000102{
Damien Miller874d77b2000-10-14 16:23:11 +1100103 Authctxt *authctxt = ctxt;
Ben Lindstrom46c16222000-12-22 01:43:59 +0000104 u_int len;
Damien Millereba71ba2000-04-29 23:57:08 +1000105 int accept = 0;
106 char *service = packet_get_string(&len);
Damien Miller48b03fc2002-01-22 23:11:40 +1100107 packet_check_eom();
Damien Millereba71ba2000-04-29 23:57:08 +1000108
Damien Miller874d77b2000-10-14 16:23:11 +1100109 if (authctxt == NULL)
110 fatal("input_service_request: no authctxt");
111
Damien Millereba71ba2000-04-29 23:57:08 +1000112 if (strcmp(service, "ssh-userauth") == 0) {
Damien Miller874d77b2000-10-14 16:23:11 +1100113 if (!authctxt->success) {
Damien Millereba71ba2000-04-29 23:57:08 +1000114 accept = 1;
115 /* now we can handle user-auth requests */
116 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
117 }
118 }
119 /* XXX all other service requests are denied */
120
121 if (accept) {
122 packet_start(SSH2_MSG_SERVICE_ACCEPT);
123 packet_put_cstring(service);
124 packet_send();
125 packet_write_wait();
126 } else {
127 debug("bad service request %s", service);
128 packet_disconnect("bad service request %s", service);
129 }
130 xfree(service);
131}
132
Ben Lindstrombba81212001-06-25 05:01:22 +0000133static void
Damien Miller630d6f42002-01-22 23:17:30 +1100134input_userauth_request(int type, u_int32_t seq, void *ctxt)
Damien Millereba71ba2000-04-29 23:57:08 +1000135{
Damien Miller874d77b2000-10-14 16:23:11 +1100136 Authctxt *authctxt = ctxt;
137 Authmethod *m = NULL;
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000138 char *user, *service, *method, *style = NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000139 int authenticated = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000140
Damien Miller874d77b2000-10-14 16:23:11 +1100141 if (authctxt == NULL)
142 fatal("input_userauth_request: no authctxt");
Damien Millereba71ba2000-04-29 23:57:08 +1000143
Damien Miller874d77b2000-10-14 16:23:11 +1100144 user = packet_get_string(NULL);
145 service = packet_get_string(NULL);
146 method = packet_get_string(NULL);
147 debug("userauth-request for user %s service %s method %s", user, service, method);
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000148 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
Damien Miller874d77b2000-10-14 16:23:11 +1100149
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000150 if ((style = strchr(user, ':')) != NULL)
151 *style++ = 0;
152
Kevin Stevesef4eea92001-02-05 12:42:17 +0000153 if (authctxt->attempt++ == 0) {
Damien Miller3a5b0232002-03-13 13:19:42 +1100154 /* setup auth context */
Kevin Steves205cc1e2002-03-22 20:43:05 +0000155 authctxt->pw = PRIVSEP(getpwnamallow(user));
156 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
Damien Miller874d77b2000-10-14 16:23:11 +1100157 authctxt->valid = 1;
158 debug2("input_userauth_request: setting up authctxt for %s", user);
159#ifdef USE_PAM
Damien Miller79418552002-04-23 20:28:48 +1000160 PRIVSEP(start_pam(authctxt->pw->pw_name));
Damien Miller874d77b2000-10-14 16:23:11 +1100161#endif
162 } else {
163 log("input_userauth_request: illegal user %s", user);
Damien Miller22e22bf2001-01-19 15:46:38 +1100164#ifdef USE_PAM
Damien Miller79418552002-04-23 20:28:48 +1000165 PRIVSEP(start_pam("NOUSER"));
Damien Miller22e22bf2001-01-19 15:46:38 +1100166#endif
Damien Miller874d77b2000-10-14 16:23:11 +1100167 }
Ben Lindstrom7ebb6352002-03-22 03:04:08 +0000168 setproctitle("%s%s", authctxt->pw ? user : "unknown",
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000169 use_privsep ? " [net]" : "");
Damien Miller874d77b2000-10-14 16:23:11 +1100170 authctxt->user = xstrdup(user);
171 authctxt->service = xstrdup(service);
Ben Lindstrom9d0c0662001-06-09 01:40:00 +0000172 authctxt->style = style ? xstrdup(style) : NULL;
Ben Lindstrom7a2073c2002-03-22 02:30:41 +0000173 if (use_privsep)
174 mm_inform_authserv(service, style);
Ben Lindstrom9d0c0662001-06-09 01:40:00 +0000175 } else if (strcmp(user, authctxt->user) != 0 ||
176 strcmp(service, authctxt->service) != 0) {
177 packet_disconnect("Change of username or service not allowed: "
178 "(%s,%s) -> (%s,%s)",
179 authctxt->user, authctxt->service, user, service);
Damien Millereba71ba2000-04-29 23:57:08 +1000180 }
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000181 /* reset state */
Damien Milleree116252001-12-21 12:42:34 +1100182 auth2_challenge_stop(authctxt);
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000183 authctxt->postponed = 0;
Damien Millerb70b61f2000-09-16 16:25:12 +1100184
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000185 /* try to authenticate user */
Damien Miller874d77b2000-10-14 16:23:11 +1100186 m = authmethod_lookup(method);
187 if (m != NULL) {
188 debug2("input_userauth_request: try method %s", method);
189 authenticated = m->userauth(authctxt);
Damien Miller874d77b2000-10-14 16:23:11 +1100190 }
Damien Miller5d57e502001-03-30 10:48:31 +1000191 userauth_finish(authctxt, authenticated, method);
192
193 xfree(service);
194 xfree(user);
195 xfree(method);
196}
197
198void
199userauth_finish(Authctxt *authctxt, int authenticated, char *method)
200{
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000201 char *methods;
202
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000203 if (!authctxt->valid && authenticated)
204 fatal("INTERNAL ERROR: authenticated invalid user %s",
205 authctxt->user);
Damien Millerb70b61f2000-09-16 16:25:12 +1100206
Damien Miller874d77b2000-10-14 16:23:11 +1100207 /* Special handling for root */
Ben Lindstromd8a90212001-02-15 03:08:27 +0000208 if (authenticated && authctxt->pw->pw_uid == 0 &&
209 !auth_root_allowed(method))
Damien Millereba71ba2000-04-29 23:57:08 +1000210 authenticated = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000211
212#ifdef USE_PAM
Damien Miller79418552002-04-23 20:28:48 +1000213 if (!use_privsep && authenticated && authctxt->user &&
214 !do_pam_account(authctxt->user, NULL))
Damien Millerb70b61f2000-09-16 16:25:12 +1100215 authenticated = 0;
Damien Millereba71ba2000-04-29 23:57:08 +1000216#endif /* USE_PAM */
217
Damien Miller874d77b2000-10-14 16:23:11 +1100218 /* Log before sending the reply */
Ben Lindstromdb65e8f2001-01-19 04:26:52 +0000219 auth_log(authctxt, authenticated, method, " ssh2");
220
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000221 if (authctxt->postponed)
222 return;
223
224 /* XXX todo: check if multiple auth methods are needed */
225 if (authenticated == 1) {
226 /* turn off userauth */
Damien Miller7d053392002-01-22 23:24:13 +1100227 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000228 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
229 packet_send();
230 packet_write_wait();
231 /* now we can break out */
232 authctxt->success = 1;
233 } else {
Damien Millere49d0962001-11-13 23:46:18 +1100234 if (authctxt->failures++ > AUTH_FAIL_MAX) {
235#ifdef WITH_AIXAUTHENTICATE
236 loginfailed(authctxt->user,
Damien Millerf3451a22002-02-05 12:40:46 +1100237 get_canonical_hostname(options.verify_reverse_mapping),
Damien Millere49d0962001-11-13 23:46:18 +1100238 "ssh");
239#endif /* WITH_AIXAUTHENTICATE */
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000240 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
Damien Millere49d0962001-11-13 23:46:18 +1100241 }
Ben Lindstromcd4349f2001-06-09 00:23:17 +0000242 methods = authmethods_get();
243 packet_start(SSH2_MSG_USERAUTH_FAILURE);
244 packet_put_cstring(methods);
245 packet_put_char(0); /* XXX partial success, unused */
246 packet_send();
247 packet_write_wait();
248 xfree(methods);
249 }
Damien Miller874d77b2000-10-14 16:23:11 +1100250}
251
Damien Miller874d77b2000-10-14 16:23:11 +1100252/* get current user */
Damien Millereba71ba2000-04-29 23:57:08 +1000253
254struct passwd*
255auth_get_user(void)
256{
Damien Miller874d77b2000-10-14 16:23:11 +1100257 return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000258}
259
Damien Miller874d77b2000-10-14 16:23:11 +1100260#define DELIM ","
Damien Millereba71ba2000-04-29 23:57:08 +1000261
Ben Lindstrom79073822001-07-04 03:42:30 +0000262static char *
Damien Miller874d77b2000-10-14 16:23:11 +1100263authmethods_get(void)
264{
Damien Miller0e3b8722002-01-22 23:26:38 +1100265 Buffer b;
Damien Miller874d77b2000-10-14 16:23:11 +1100266 char *list;
Ben Lindstrom511bb242002-06-06 20:52:37 +0000267 int i;
Damien Miller874d77b2000-10-14 16:23:11 +1100268
Damien Miller0e3b8722002-01-22 23:26:38 +1100269 buffer_init(&b);
Ben Lindstrom511bb242002-06-06 20:52:37 +0000270 for (i = 0; authmethods[i] != NULL; i++) {
271 if (strcmp(authmethods[i]->name, "none") == 0)
Damien Miller874d77b2000-10-14 16:23:11 +1100272 continue;
Ben Lindstrom511bb242002-06-06 20:52:37 +0000273 if (authmethods[i]->enabled != NULL &&
274 *(authmethods[i]->enabled) != 0) {
Damien Miller0e3b8722002-01-22 23:26:38 +1100275 if (buffer_len(&b) > 0)
276 buffer_append(&b, ",", 1);
Ben Lindstrom511bb242002-06-06 20:52:37 +0000277 buffer_append(&b, authmethods[i]->name,
278 strlen(authmethods[i]->name));
Damien Millereba71ba2000-04-29 23:57:08 +1000279 }
280 }
Damien Miller0e3b8722002-01-22 23:26:38 +1100281 buffer_append(&b, "\0", 1);
282 list = xstrdup(buffer_ptr(&b));
283 buffer_free(&b);
Damien Miller874d77b2000-10-14 16:23:11 +1100284 return list;
285}
286
Ben Lindstrombba81212001-06-25 05:01:22 +0000287static Authmethod *
Damien Miller874d77b2000-10-14 16:23:11 +1100288authmethod_lookup(const char *name)
289{
Ben Lindstrom511bb242002-06-06 20:52:37 +0000290 int i;
291
Damien Miller874d77b2000-10-14 16:23:11 +1100292 if (name != NULL)
Ben Lindstrom511bb242002-06-06 20:52:37 +0000293 for (i = 0; authmethods[i] != NULL; i++)
294 if (authmethods[i]->enabled != NULL &&
295 *(authmethods[i]->enabled) != 0 &&
296 strcmp(name, authmethods[i]->name) == 0)
297 return authmethods[i];
298 debug2("Unrecognized authentication method name: %s",
299 name ? name : "NULL");
Damien Miller874d77b2000-10-14 16:23:11 +1100300 return NULL;
Damien Millereba71ba2000-04-29 23:57:08 +1000301}