1/*
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.
12 *
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 */
24
25#include "includes.h"
26RCSID("$OpenBSD: auth2.c,v 1.107 2004/07/28 09:40:29 markus Exp $");
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27RCSID("$FreeBSD: head/crypto/openssh/auth2.c 149753 2005-09-03 07:04:25Z des $");
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| 27RCSID("$FreeBSD: head/crypto/openssh/auth2.c 157019 2006-03-22 20:41:37Z des $"); |
28
29#include "canohost.h"
30#include "ssh2.h"
31#include "xmalloc.h"
32#include "packet.h"
33#include "log.h"
34#include "servconf.h"
35#include "compat.h"
36#include "auth.h"
37#include "dispatch.h"
38#include "pathnames.h"
39#include "monitor_wrap.h"
40#include "buffer.h"
41
42#ifdef GSSAPI
43#include "ssh-gss.h"
44#endif
45
46/* import */
47extern ServerOptions options;
48extern u_char *session_id2;
49extern u_int session_id2_len;
50extern Buffer loginmsg;
51
52/* methods */
53
54extern Authmethod method_none;
55extern Authmethod method_pubkey;
56extern Authmethod method_passwd;
57extern Authmethod method_kbdint;
58extern Authmethod method_hostbased;
59#ifdef GSSAPI
60extern Authmethod method_gssapi;
61#endif
62
63Authmethod *authmethods[] = {
64 &method_none,
65 &method_pubkey,
66#ifdef GSSAPI
67 &method_gssapi,
68#endif
69 &method_passwd,
70 &method_kbdint,
71 &method_hostbased,
72 NULL
73};
74
75/* protocol */
76
77static void input_service_request(int, u_int32_t, void *);
78static void input_userauth_request(int, u_int32_t, void *);
79
80/* helper */
81static Authmethod *authmethod_lookup(const char *);
82static char *authmethods_get(void);
83int user_key_allowed(struct passwd *, Key *);
84
85/*
86 * loop until authctxt->success == TRUE
87 */
88
89void
90do_authentication2(Authctxt *authctxt)
91{
92 /* challenge-response is implemented via keyboard interactive */
93 if (options.challenge_response_authentication)
94 options.kbd_interactive_authentication = 1;
95
96 dispatch_init(&dispatch_protocol_error);
97 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
98 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
99}
100
101static void
102input_service_request(int type, u_int32_t seq, void *ctxt)
103{
104 Authctxt *authctxt = ctxt;
105 u_int len;
106 int acceptit = 0;
107 char *service = packet_get_string(&len);
108 packet_check_eom();
109
110 if (authctxt == NULL)
111 fatal("input_service_request: no authctxt");
112
113 if (strcmp(service, "ssh-userauth") == 0) {
114 if (!authctxt->success) {
115 acceptit = 1;
116 /* now we can handle user-auth requests */
117 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
118 }
119 }
120 /* XXX all other service requests are denied */
121
122 if (acceptit) {
123 packet_start(SSH2_MSG_SERVICE_ACCEPT);
124 packet_put_cstring(service);
125 packet_send();
126 packet_write_wait();
127 } else {
128 debug("bad service request %s", service);
129 packet_disconnect("bad service request %s", service);
130 }
131 xfree(service);
132}
133
134static void
135input_userauth_request(int type, u_int32_t seq, void *ctxt)
136{
137 Authctxt *authctxt = ctxt;
138 Authmethod *m = NULL;
139 char *user, *service, *method, *style = NULL;
140 int authenticated = 0;
141#ifdef HAVE_LOGIN_CAP
142 login_cap_t *lc;
143 const char *from_host, *from_ip;
144
145 from_host = get_canonical_hostname(options.use_dns);
146 from_ip = get_remote_ipaddr();
147#endif
148
149 if (authctxt == NULL)
150 fatal("input_userauth_request: no authctxt");
151
152 user = packet_get_string(NULL);
153 service = packet_get_string(NULL);
154 method = packet_get_string(NULL);
155 debug("userauth-request for user %s service %s method %s", user, service, method);
156 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
157
158 if ((style = strchr(user, ':')) != NULL)
159 *style++ = 0;
160
161 if (authctxt->attempt++ == 0) {
162 /* setup auth context */
163 authctxt->pw = PRIVSEP(getpwnamallow(user));
164 authctxt->user = xstrdup(user);
165 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
166 authctxt->valid = 1;
167 debug2("input_userauth_request: setting up authctxt for %s", user);
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168#ifdef USE_PAM
169 if (options.use_pam)
170 PRIVSEP(start_pam(authctxt));
171#endif
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168 } else {
169 logit("input_userauth_request: invalid user %s", user);
170 authctxt->pw = fakepw();
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175#ifdef USE_PAM
176 if (options.use_pam)
177 PRIVSEP(start_pam(authctxt));
178#endif
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171#ifdef SSH_AUDIT_EVENTS
172 PRIVSEP(audit_event(SSH_INVALID_USER));
173#endif
174 }
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175#ifdef USE_PAM
176 if (options.use_pam)
177 PRIVSEP(start_pam(authctxt));
178#endif |
179 setproctitle("%s%s", authctxt->valid ? user : "unknown",
180 use_privsep ? " [net]" : "");
181 authctxt->service = xstrdup(service);
182 authctxt->style = style ? xstrdup(style) : NULL;
183 if (use_privsep)
184 mm_inform_authserv(service, style);
185 } else if (strcmp(user, authctxt->user) != 0 ||
186 strcmp(service, authctxt->service) != 0) {
187 packet_disconnect("Change of username or service not allowed: "
188 "(%s,%s) -> (%s,%s)",
189 authctxt->user, authctxt->service, user, service);
190 }
191
192#ifdef HAVE_LOGIN_CAP
193 if (authctxt->pw != NULL) {
194 lc = login_getpwclass(authctxt->pw);
195 if (lc == NULL)
196 lc = login_getclassbyname(NULL, authctxt->pw);
197 if (!auth_hostok(lc, from_host, from_ip)) {
198 logit("Denied connection for %.200s from %.200s [%.200s].",
199 authctxt->pw->pw_name, from_host, from_ip);
200 packet_disconnect("Sorry, you are not allowed to connect.");
201 }
202 if (!auth_timeok(lc, time(NULL))) {
203 logit("LOGIN %.200s REFUSED (TIME) FROM %.200s",
204 authctxt->pw->pw_name, from_host);
205 packet_disconnect("Logins not available right now.");
206 }
207 login_close(lc);
208 lc = NULL;
209 }
210#endif /* HAVE_LOGIN_CAP */
211
212 /* reset state */
213 auth2_challenge_stop(authctxt);
214
215#ifdef GSSAPI
216 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
217 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
218#endif
219
220 authctxt->postponed = 0;
221
222 /* try to authenticate user */
223 m = authmethod_lookup(method);
224 if (m != NULL) {
225 debug2("input_userauth_request: try method %s", method);
226 authenticated = m->userauth(authctxt);
227 }
228 userauth_finish(authctxt, authenticated, method);
229
230 xfree(service);
231 xfree(user);
232 xfree(method);
233}
234
235void
236userauth_finish(Authctxt *authctxt, int authenticated, char *method)
237{
238 char *methods;
239
240 if (!authctxt->valid && authenticated)
241 fatal("INTERNAL ERROR: authenticated invalid user %s",
242 authctxt->user);
243
244 /* Special handling for root */
245 if (authenticated && authctxt->pw->pw_uid == 0 &&
246 !auth_root_allowed(method)) {
247 authenticated = 0;
248#ifdef SSH_AUDIT_EVENTS
249 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
250#endif
251 }
252
253#ifdef USE_PAM
254 if (options.use_pam && authenticated) {
255 if (!PRIVSEP(do_pam_account())) {
256 /* if PAM returned a message, send it to the user */
257 if (buffer_len(&loginmsg) > 0) {
258 buffer_append(&loginmsg, "\0", 1);
259 userauth_send_banner(buffer_ptr(&loginmsg));
260 packet_write_wait();
261 }
262 fatal("Access denied for user %s by PAM account "
263 "configuration", authctxt->user);
264 }
265 }
266#endif
267
268#ifdef _UNICOS
269 if (authenticated && cray_access_denied(authctxt->user)) {
270 authenticated = 0;
271 fatal("Access denied for user %s.",authctxt->user);
272 }
273#endif /* _UNICOS */
274
275 /* Log before sending the reply */
276 auth_log(authctxt, authenticated, method, " ssh2");
277
278 if (authctxt->postponed)
279 return;
280
281 /* XXX todo: check if multiple auth methods are needed */
282 if (authenticated == 1) {
283 /* turn off userauth */
284 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
285 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
286 packet_send();
287 packet_write_wait();
288 /* now we can break out */
289 authctxt->success = 1;
290 } else {
291 if (authctxt->failures++ > options.max_authtries) {
292#ifdef SSH_AUDIT_EVENTS
293 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
294#endif
295 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
296 }
297 methods = authmethods_get();
298 packet_start(SSH2_MSG_USERAUTH_FAILURE);
299 packet_put_cstring(methods);
300 packet_put_char(0); /* XXX partial success, unused */
301 packet_send();
302 packet_write_wait();
303 xfree(methods);
304 }
305}
306
307#define DELIM ","
308
309static char *
310authmethods_get(void)
311{
312 Buffer b;
313 char *list;
314 int i;
315
316 buffer_init(&b);
317 for (i = 0; authmethods[i] != NULL; i++) {
318 if (strcmp(authmethods[i]->name, "none") == 0)
319 continue;
320 if (authmethods[i]->enabled != NULL &&
321 *(authmethods[i]->enabled) != 0) {
322 if (buffer_len(&b) > 0)
323 buffer_append(&b, ",", 1);
324 buffer_append(&b, authmethods[i]->name,
325 strlen(authmethods[i]->name));
326 }
327 }
328 buffer_append(&b, "\0", 1);
329 list = xstrdup(buffer_ptr(&b));
330 buffer_free(&b);
331 return list;
332}
333
334static Authmethod *
335authmethod_lookup(const char *name)
336{
337 int i;
338
339 if (name != NULL)
340 for (i = 0; authmethods[i] != NULL; i++)
341 if (authmethods[i]->enabled != NULL &&
342 *(authmethods[i]->enabled) != 0 &&
343 strcmp(name, authmethods[i]->name) == 0)
344 return authmethods[i];
345 debug2("Unrecognized authentication method name: %s",
346 name ? name : "NULL");
347 return NULL;
348}
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