1 /* $OpenBSD: auth2.c,v 1.113 2006/08/03 03:34:41 deraadt 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>
45 #include "pathnames.h"
51 #include "monitor_wrap.h"
54 extern ServerOptions options;
55 extern u_char *session_id2;
56 extern u_int session_id2_len;
57 extern Buffer loginmsg;
61 extern Authmethod method_none;
62 extern Authmethod method_pubkey;
63 extern Authmethod method_passwd;
64 extern Authmethod method_kbdint;
65 extern Authmethod method_hostbased;
67 extern Authmethod method_external;
68 extern Authmethod method_gsskeyex;
69 extern Authmethod method_gssapi;
70 extern Authmethod method_gssapi_compat;
73 Authmethod *authmethods[] = {
80 &method_gssapi_compat,
90 static void input_service_request(int, u_int32_t, void *);
91 static void input_userauth_request(int, u_int32_t, void *);
94 static Authmethod *authmethod_lookup(const char *);
95 static char *authmethods_get(void);
96 int user_key_allowed(struct passwd *, Key *);
99 * loop until authctxt->success == TRUE
103 do_authentication2(Authctxt *authctxt)
105 /* challenge-response is implemented via keyboard interactive */
106 if (options.challenge_response_authentication)
107 options.kbd_interactive_authentication = 1;
109 dispatch_init(&dispatch_protocol_error);
110 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
111 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
116 input_service_request(int type, u_int32_t seq, void *ctxt)
118 Authctxt *authctxt = ctxt;
121 char *service = packet_get_string(&len);
124 if (authctxt == NULL)
125 fatal("input_service_request: no authctxt");
127 if (strcmp(service, "ssh-userauth") == 0) {
128 if (!authctxt->success) {
130 /* now we can handle user-auth requests */
131 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
134 /* XXX all other service requests are denied */
137 packet_start(SSH2_MSG_SERVICE_ACCEPT);
138 packet_put_cstring(service);
142 debug("bad service request %s", service);
143 packet_disconnect("bad service request %s", service);
150 input_userauth_request(int type, u_int32_t seq, void *ctxt)
152 Authctxt *authctxt = ctxt;
153 Authmethod *m = NULL;
154 char *user, *service, *method, *style = NULL;
155 int authenticated = 0;
157 if (authctxt == NULL)
158 fatal("input_userauth_request: no authctxt");
160 user = packet_get_string(NULL);
161 service = packet_get_string(NULL);
162 method = packet_get_string(NULL);
165 if (user[0] == '\0') {
166 debug("received empty username for %s", method);
167 if (strcmp(method, "external-keyx") == 0 ||
168 strcmp(method, "gssapi-keyex") == 0) {
170 PRIVSEP(ssh_gssapi_localname(&lname));
171 if (lname && lname[0] != '\0') {
174 debug("set username to %s from gssapi context", user);
176 debug("failed to set username from gssapi context");
177 packet_send_debug("failed to set username from gssapi context");
183 debug("userauth-request for user %s service %s method %s",
184 user[0] ? user : "<implicit>", service, method);
185 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
187 if ((style = strchr(user, ':')) != NULL)
190 /* If first time or username changed or implicit username,
191 setup/reset authentication context. */
192 if ((authctxt->attempt++ == 0) ||
193 (strcmp(user, authctxt->user) != 0) ||
194 (strcmp(user, "") == 0)) {
195 if (authctxt->user) {
196 xfree(authctxt->user);
197 authctxt->user = NULL;
201 /* If we're going to set the username based on the
202 GSSAPI context later, then wait until then to
203 verify it. Just put in placeholders for now. */
204 if ((strcmp(user, "") == 0) &&
205 ((strcmp(method, "gssapi") == 0) ||
206 (strcmp(method, "gssapi-with-mic") == 0))) {
207 authctxt->pw = fakepw();
208 authctxt->user = xstrdup(user);
211 authctxt->pw = PRIVSEP(getpwnamallow(user));
212 authctxt->user = xstrdup(user);
213 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
215 debug2("input_userauth_request: setting up authctxt for %s", user);
217 logit("input_userauth_request: invalid user %s", user);
218 authctxt->pw = fakepw();
219 #ifdef SSH_AUDIT_EVENTS
220 PRIVSEP(audit_event(SSH_INVALID_USER));
224 } /* endif for setting username based on GSSAPI context */
228 PRIVSEP(start_pam(authctxt));
230 setproctitle("%s%s", authctxt->valid ? user : "unknown",
231 use_privsep ? " [net]" : "");
233 if (authctxt->attempt == 1) {
235 authctxt->service = xstrdup(service);
236 authctxt->style = style ? xstrdup(style) : NULL;
238 mm_inform_authserv(service, style);
240 } /* if (authctxt->attempt == 1) */
243 if (strcmp(service, authctxt->service) != 0) {
244 packet_disconnect("Change of service not allowed: "
245 "(%s,%s) -> (%s,%s)",
246 authctxt->user, authctxt->service, user, service);
249 auth2_challenge_stop(authctxt);
252 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
253 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
256 authctxt->postponed = 0;
257 authctxt->server_caused_failure = 0;
259 /* try to authenticate user */
260 m = authmethod_lookup(method);
262 debug2("input_userauth_request: try method %s", method);
263 authenticated = m->userauth(authctxt);
265 userauth_finish(authctxt, authenticated, method);
273 userauth_finish(Authctxt *authctxt, int authenticated, char *method)
277 if (!authctxt->valid && authenticated)
278 fatal("INTERNAL ERROR: authenticated invalid user %s",
281 /* Special handling for root */
282 if (authenticated && authctxt->pw->pw_uid == 0 &&
283 !auth_root_allowed(method)) {
285 #ifdef SSH_AUDIT_EVENTS
286 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
291 if (options.use_pam && authenticated) {
292 if (!PRIVSEP(do_pam_account())) {
293 /* if PAM returned a message, send it to the user */
294 if (buffer_len(&loginmsg) > 0) {
295 buffer_append(&loginmsg, "\0", 1);
296 userauth_send_banner(buffer_ptr(&loginmsg));
299 fatal("Access denied for user %s by PAM account "
300 "configuration", authctxt->user);
306 if (authenticated && cray_access_denied(authctxt->user)) {
308 fatal("Access denied for user %s.",authctxt->user);
312 /* Log before sending the reply */
313 auth_log(authctxt, authenticated, method, " ssh2");
315 if (authctxt->postponed)
318 /* XXX todo: check if multiple auth methods are needed */
319 if (authenticated == 1) {
320 /* turn off userauth */
321 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
322 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
325 /* now we can break out */
326 authctxt->success = 1;
328 /* Dont count server configuration issues against the client */
329 if (!authctxt->server_caused_failure &&
330 authctxt->failures++ > options.max_authtries) {
331 #ifdef SSH_AUDIT_EVENTS
332 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
334 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
336 methods = authmethods_get();
337 packet_start(SSH2_MSG_USERAUTH_FAILURE);
338 packet_put_cstring(methods);
339 packet_put_char(0); /* XXX partial success, unused */
349 authmethods_get(void)
356 for (i = 0; authmethods[i] != NULL; i++) {
357 if (strcmp(authmethods[i]->name, "none") == 0)
359 if (authmethods[i]->enabled != NULL &&
360 *(authmethods[i]->enabled) != 0) {
361 if (buffer_len(&b) > 0)
362 buffer_append(&b, ",", 1);
363 buffer_append(&b, authmethods[i]->name,
364 strlen(authmethods[i]->name));
367 buffer_append(&b, "\0", 1);
368 list = xstrdup(buffer_ptr(&b));
374 authmethod_lookup(const char *name)
379 for (i = 0; authmethods[i] != NULL; i++)
380 if (authmethods[i]->enabled != NULL &&
381 *(authmethods[i]->enabled) != 0 &&
382 strcmp(name, authmethods[i]->name) == 0)
383 return authmethods[i];
384 debug2("Unrecognized authentication method name: %s",
385 name ? name : "NULL");