Merge branch 'vendor/OPENSSH'
[dragonfly.git] / crypto / openssh / auth2.c
1 /* $OpenBSD: auth2.c,v 1.120 2008/11/04 08:22:12 djm Exp $ */
2 /*
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.
13  *
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  */
25
26 #include "includes.h"
27
28 #include <sys/types.h>
29 #include <sys/stat.h>
30 #include <sys/uio.h>
31
32 #include <fcntl.h>
33 #include <pwd.h>
34 #include <stdarg.h>
35 #include <string.h>
36 #include <unistd.h>
37
38 #include "xmalloc.h"
39 #include "canohost.h"
40 #include "atomicio.h"
41 #include "ssh2.h"
42 #include "packet.h"
43 #include "log.h"
44 #include "buffer.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
54 #ifdef GSSAPI
55 #include "ssh-gss.h"
56 #endif
57 #include "monitor_wrap.h"
58
59 /* import */
60 extern ServerOptions options;
61 extern u_char *session_id2;
62 extern u_int session_id2_len;
63 extern Buffer loginmsg;
64
65 /* methods */
66
67 extern Authmethod method_none;
68 extern Authmethod method_pubkey;
69 extern Authmethod method_passwd;
70 extern Authmethod method_kbdint;
71 extern Authmethod method_hostbased;
72 #ifdef GSSAPI
73 extern Authmethod method_gssapi;
74 #endif
75 #ifdef JPAKE
76 extern Authmethod method_jpake;
77 #endif
78
79 Authmethod *authmethods[] = {
80         &method_none,
81         &method_pubkey,
82 #ifdef GSSAPI
83         &method_gssapi,
84 #endif
85 #ifdef JPAKE
86         &method_jpake,
87 #endif
88         &method_passwd,
89         &method_kbdint,
90         &method_hostbased,
91         NULL
92 };
93
94 /* protocol */
95
96 static void input_service_request(int, u_int32_t, void *);
97 static void input_userauth_request(int, u_int32_t, void *);
98
99 /* helper */
100 static Authmethod *authmethod_lookup(const char *);
101 static char *authmethods_get(void);
102
103 char *
104 auth2_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         }
117         if (st.st_size > 1*1024*1024) {
118                 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) {
128                 xfree(banner);
129                 return (NULL);
130         }
131         banner[n] = '\0';
132
133         return (banner);
134 }
135
136 void
137 userauth_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
149 static void
150 userauth_banner(void)
151 {
152         char *banner = NULL;
153
154         if (options.banner == NULL ||
155             strcasecmp(options.banner, "none") == 0 ||
156             (datafellows & SSH_BUG_BANNER) != 0)
157                 return;
158
159         if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
160                 goto done;
161         userauth_send_banner(banner);
162
163 done:
164         if (banner)
165                 xfree(banner);
166 }
167
168 /*
169  * loop until authctxt->success == TRUE
170  */
171 void
172 do_authentication2(Authctxt *authctxt)
173 {
174         dispatch_init(&dispatch_protocol_error);
175         dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
176         dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
177 }
178
179 /*ARGSUSED*/
180 static void
181 input_service_request(int type, u_int32_t seq, void *ctxt)
182 {
183         Authctxt *authctxt = ctxt;
184         u_int len;
185         int acceptit = 0;
186         char *service = packet_get_string(&len);
187         packet_check_eom();
188
189         if (authctxt == NULL)
190                 fatal("input_service_request: no authctxt");
191
192         if (strcmp(service, "ssh-userauth") == 0) {
193                 if (!authctxt->success) {
194                         acceptit = 1;
195                         /* now we can handle user-auth requests */
196                         dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
197                 }
198         }
199         /* XXX all other service requests are denied */
200
201         if (acceptit) {
202                 packet_start(SSH2_MSG_SERVICE_ACCEPT);
203                 packet_put_cstring(service);
204                 packet_send();
205                 packet_write_wait();
206         } else {
207                 debug("bad service request %s", service);
208                 packet_disconnect("bad service request %s", service);
209         }
210         xfree(service);
211 }
212
213 /*ARGSUSED*/
214 static void
215 input_userauth_request(int type, u_int32_t seq, void *ctxt)
216 {
217         Authctxt *authctxt = ctxt;
218         Authmethod *m = NULL;
219         char *user, *service, *method, *style = NULL;
220         int authenticated = 0;
221 #ifdef HAVE_LOGIN_CAP
222         login_cap_t *lc;
223         const char *from_host, *from_ip;
224
225         from_host = get_canonical_hostname(options.use_dns);
226         from_ip = get_remote_ipaddr();
227 #endif
228
229         if (authctxt == NULL)
230                 fatal("input_userauth_request: no authctxt");
231
232         user = packet_get_string(NULL);
233         service = packet_get_string(NULL);
234         method = packet_get_string(NULL);
235         debug("userauth-request for user %s service %s method %s", user, service, method);
236         debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
237
238         if ((style = strchr(user, ':')) != NULL)
239                 *style++ = 0;
240
241         if (authctxt->attempt++ == 0) {
242                 /* setup auth context */
243                 authctxt->pw = PRIVSEP(getpwnamallow(user));
244                 authctxt->user = xstrdup(user);
245                 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
246                         authctxt->valid = 1;
247                         debug2("input_userauth_request: setting up authctxt for %s", user);
248                 } else {
249                         logit("input_userauth_request: invalid user %s", user);
250                         authctxt->pw = fakepw();
251 #ifdef SSH_AUDIT_EVENTS
252                         PRIVSEP(audit_event(SSH_INVALID_USER));
253 #endif
254                 }
255 #ifdef USE_PAM
256                 if (options.use_pam)
257                         PRIVSEP(start_pam(authctxt));
258 #endif
259                 setproctitle("%s%s", authctxt->valid ? user : "unknown",
260                     use_privsep ? " [net]" : "");
261                 authctxt->service = xstrdup(service);
262                 authctxt->style = style ? xstrdup(style) : NULL;
263                 if (use_privsep)
264                         mm_inform_authserv(service, style);
265                 userauth_banner();
266         } else if (strcmp(user, authctxt->user) != 0 ||
267             strcmp(service, authctxt->service) != 0) {
268                 packet_disconnect("Change of username or service not allowed: "
269                     "(%s,%s) -> (%s,%s)",
270                     authctxt->user, authctxt->service, user, service);
271         }
272
273 #ifdef HAVE_LOGIN_CAP
274         if (authctxt->pw != NULL) {
275                 lc = login_getpwclass(authctxt->pw);
276                 if (lc == NULL)
277                         lc = login_getclassbyname(NULL, authctxt->pw);
278                 if (!auth_hostok(lc, from_host, from_ip)) {
279                         logit("Denied connection for %.200s from %.200s [%.200s].",
280                             authctxt->pw->pw_name, from_host, from_ip);
281                         packet_disconnect("Sorry, you are not allowed to connect.");
282                 }
283                 if (!auth_timeok(lc, time(NULL))) {
284                         logit("LOGIN %.200s REFUSED (TIME) FROM %.200s",
285                             authctxt->pw->pw_name, from_host);
286                         packet_disconnect("Logins not available right now.");
287                 }
288                 login_close(lc);
289                 lc = NULL;
290         }
291 #endif  /* HAVE_LOGIN_CAP */
292
293         /* reset state */
294         auth2_challenge_stop(authctxt);
295 #ifdef JPAKE
296         auth2_jpake_stop(authctxt);
297 #endif
298
299 #ifdef GSSAPI
300         /* XXX move to auth2_gssapi_stop() */
301         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
302         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
303 #endif
304
305         authctxt->postponed = 0;
306
307         /* try to authenticate user */
308         m = authmethod_lookup(method);
309         if (m != NULL && authctxt->failures < options.max_authtries) {
310                 debug2("input_userauth_request: try method %s", method);
311                 authenticated = m->userauth(authctxt);
312         }
313         userauth_finish(authctxt, authenticated, method);
314
315         xfree(service);
316         xfree(user);
317         xfree(method);
318 }
319
320 void
321 userauth_finish(Authctxt *authctxt, int authenticated, char *method)
322 {
323         char *methods;
324
325         if (!authctxt->valid && authenticated)
326                 fatal("INTERNAL ERROR: authenticated invalid user %s",
327                     authctxt->user);
328
329         /* Special handling for root */
330         if (authenticated && authctxt->pw->pw_uid == 0 &&
331             !auth_root_allowed(method)) {
332                 authenticated = 0;
333 #ifdef SSH_AUDIT_EVENTS
334                 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
335 #endif
336         }
337
338 #ifdef USE_PAM
339         if (options.use_pam && authenticated) {
340                 if (!PRIVSEP(do_pam_account())) {
341                         /* if PAM returned a message, send it to the user */
342                         if (buffer_len(&loginmsg) > 0) {
343                                 buffer_append(&loginmsg, "\0", 1);
344                                 userauth_send_banner(buffer_ptr(&loginmsg));
345                                 packet_write_wait();
346                         }
347                         fatal("Access denied for user %s by PAM account "
348                             "configuration", authctxt->user);
349                 }
350         }
351 #endif
352
353 #ifdef _UNICOS
354         if (authenticated && cray_access_denied(authctxt->user)) {
355                 authenticated = 0;
356                 fatal("Access denied for user %s.",authctxt->user);
357         }
358 #endif /* _UNICOS */
359
360         /* Log before sending the reply */
361         auth_log(authctxt, authenticated, method, " ssh2");
362
363         if (authctxt->postponed)
364                 return;
365
366         /* XXX todo: check if multiple auth methods are needed */
367         if (authenticated == 1) {
368                 /* turn off userauth */
369                 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
370                 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
371                 packet_send();
372                 packet_write_wait();
373                 /* now we can break out */
374                 authctxt->success = 1;
375         } else {
376
377                 /* Allow initial try of "none" auth without failure penalty */
378                 if (authctxt->attempt > 1 || strcmp(method, "none") != 0)
379                         authctxt->failures++;
380                 if (authctxt->failures >= options.max_authtries) {
381 #ifdef SSH_AUDIT_EVENTS
382                         PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
383 #endif
384                         packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
385                 }
386                 methods = authmethods_get();
387                 packet_start(SSH2_MSG_USERAUTH_FAILURE);
388                 packet_put_cstring(methods);
389                 packet_put_char(0);     /* XXX partial success, unused */
390                 packet_send();
391                 packet_write_wait();
392                 xfree(methods);
393         }
394 }
395
396 static char *
397 authmethods_get(void)
398 {
399         Buffer b;
400         char *list;
401         int i;
402
403         buffer_init(&b);
404         for (i = 0; authmethods[i] != NULL; i++) {
405                 if (strcmp(authmethods[i]->name, "none") == 0)
406                         continue;
407                 if (authmethods[i]->enabled != NULL &&
408                     *(authmethods[i]->enabled) != 0) {
409                         if (buffer_len(&b) > 0)
410                                 buffer_append(&b, ",", 1);
411                         buffer_append(&b, authmethods[i]->name,
412                             strlen(authmethods[i]->name));
413                 }
414         }
415         buffer_append(&b, "\0", 1);
416         list = xstrdup(buffer_ptr(&b));
417         buffer_free(&b);
418         return list;
419 }
420
421 static Authmethod *
422 authmethod_lookup(const char *name)
423 {
424         int i;
425
426         if (name != NULL)
427                 for (i = 0; authmethods[i] != NULL; i++)
428                         if (authmethods[i]->enabled != NULL &&
429                             *(authmethods[i]->enabled) != 0 &&
430                             strcmp(name, authmethods[i]->name) == 0)
431                                 return authmethods[i];
432         debug2("Unrecognized authentication method name: %s",
433             name ? name : "NULL");
434         return NULL;
435 }
436