Merge branch 'vendor/OPENSSH'
[dragonfly.git] / crypto / openssh / auth2.c
1 /* $OpenBSD: auth2.c,v 1.124 2011/12/07 05:44:38 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 "atomicio.h"
39 #include "xmalloc.h"
40 #include "ssh2.h"
41 #include "packet.h"
42 #include "log.h"
43 #include "buffer.h"
44 #include "servconf.h"
45 #include "compat.h"
46 #include "key.h"
47 #include "hostfile.h"
48 #include "auth.h"
49 #include "dispatch.h"
50 #include "pathnames.h"
51 #include "buffer.h"
52 #include "canohost.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 static int log_flag = 0;
80
81
82 Authmethod *authmethods[] = {
83         &method_none,
84         &method_pubkey,
85 #ifdef GSSAPI
86         &method_gssapi,
87 #endif
88 #ifdef JPAKE
89         &method_jpake,
90 #endif
91         &method_passwd,
92         &method_kbdint,
93         &method_hostbased,
94         NULL
95 };
96
97 /* protocol */
98
99 static void input_service_request(int, u_int32_t, void *);
100 static void input_userauth_request(int, u_int32_t, void *);
101
102 /* helper */
103 static Authmethod *authmethod_lookup(const char *);
104 static char *authmethods_get(void);
105
106 char *
107 auth2_read_banner(void)
108 {
109         struct stat st;
110         char *banner = NULL;
111         size_t len, n;
112         int fd;
113
114         if ((fd = open(options.banner, O_RDONLY)) == -1)
115                 return (NULL);
116         if (fstat(fd, &st) == -1) {
117                 close(fd);
118                 return (NULL);
119         }
120         if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
121                 close(fd);
122                 return (NULL);
123         }
124
125         len = (size_t)st.st_size;               /* truncate */
126         banner = xmalloc(len + 1);
127         n = atomicio(read, fd, banner, len);
128         close(fd);
129
130         if (n != len) {
131                 xfree(banner);
132                 return (NULL);
133         }
134         banner[n] = '\0';
135
136         return (banner);
137 }
138
139 void
140 userauth_send_banner(const char *msg)
141 {
142         if (datafellows & SSH_BUG_BANNER)
143                 return;
144
145         packet_start(SSH2_MSG_USERAUTH_BANNER);
146         packet_put_cstring(msg);
147         packet_put_cstring("");         /* language, unused */
148         packet_send();
149         debug("%s: sent", __func__);
150 }
151
152 static void
153 userauth_banner(void)
154 {
155         char *banner = NULL;
156
157         if (options.banner == NULL ||
158             strcasecmp(options.banner, "none") == 0 ||
159             (datafellows & SSH_BUG_BANNER) != 0)
160                 return;
161
162         if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
163                 goto done;
164         userauth_send_banner(banner);
165
166 done:
167         if (banner)
168                 xfree(banner);
169 }
170
171 /*
172  * loop until authctxt->success == TRUE
173  */
174 void
175 do_authentication2(Authctxt *authctxt)
176 {
177         dispatch_init(&dispatch_protocol_error);
178         dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
179         dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
180 }
181
182 /*ARGSUSED*/
183 static void
184 input_service_request(int type, u_int32_t seq, void *ctxt)
185 {
186         Authctxt *authctxt = ctxt;
187         u_int len;
188         int acceptit = 0;
189         char *service = packet_get_cstring(&len);
190         packet_check_eom();
191
192         if (authctxt == NULL)
193                 fatal("input_service_request: no authctxt");
194
195         if (strcmp(service, "ssh-userauth") == 0) {
196                 if (!authctxt->success) {
197                         acceptit = 1;
198                         /* now we can handle user-auth requests */
199                         dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
200                 }
201         }
202         /* XXX all other service requests are denied */
203
204         if (acceptit) {
205                 packet_start(SSH2_MSG_SERVICE_ACCEPT);
206                 packet_put_cstring(service);
207                 packet_send();
208                 packet_write_wait();
209         } else {
210                 debug("bad service request %s", service);
211                 packet_disconnect("bad service request %s", service);
212         }
213         xfree(service);
214 }
215
216 /*ARGSUSED*/
217 static void
218 input_userauth_request(int type, u_int32_t seq, void *ctxt)
219 {
220         Authctxt *authctxt = ctxt;
221         Authmethod *m = NULL;
222         char *user, *service, *method, *style = NULL;
223         int authenticated = 0;
224 #ifdef HAVE_LOGIN_CAP
225         login_cap_t *lc;
226         const char *from_host, *from_ip;
227
228         from_host = get_canonical_hostname(options.use_dns);
229         from_ip = get_remote_ipaddr();
230 #endif
231
232         if (authctxt == NULL)
233                 fatal("input_userauth_request: no authctxt");
234
235         user = packet_get_cstring(NULL);
236         service = packet_get_cstring(NULL);
237         method = packet_get_cstring(NULL);
238         debug("userauth-request for user %s service %s method %s", user, service, method);
239         if (!log_flag) {
240                 logit("SSH: Server;Ltype: Authname;Remote: %s-%d;Name: %s",
241                       get_remote_ipaddr(), get_remote_port(), user);
242                 log_flag = 1;
243         }
244         debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
245
246         if ((style = strchr(user, ':')) != NULL)
247                 *style++ = 0;
248
249         if (authctxt->attempt++ == 0) {
250                 /* setup auth context */
251                 authctxt->pw = PRIVSEP(getpwnamallow(user));
252                 authctxt->user = xstrdup(user);
253                 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
254                         authctxt->valid = 1;
255                         debug2("input_userauth_request: setting up authctxt for %s", user);
256                 } else {
257                         logit("input_userauth_request: invalid user %s", user);
258                         authctxt->pw = fakepw();
259 #ifdef SSH_AUDIT_EVENTS
260                         PRIVSEP(audit_event(SSH_INVALID_USER));
261 #endif
262                 }
263 #ifdef USE_PAM
264                 if (options.use_pam)
265                         PRIVSEP(start_pam(authctxt));
266 #endif
267                 setproctitle("%s%s", authctxt->valid ? user : "unknown",
268                     use_privsep ? " [net]" : "");
269                 authctxt->service = xstrdup(service);
270                 authctxt->style = style ? xstrdup(style) : NULL;
271                 if (use_privsep)
272                         mm_inform_authserv(service, style);
273                 userauth_banner();
274         } else if (strcmp(user, authctxt->user) != 0 ||
275             strcmp(service, authctxt->service) != 0) {
276                 packet_disconnect("Change of username or service not allowed: "
277                     "(%s,%s) -> (%s,%s)",
278                     authctxt->user, authctxt->service, user, service);
279         }
280
281 #ifdef HAVE_LOGIN_CAP
282         if (authctxt->pw != NULL) {
283                 lc = login_getpwclass(authctxt->pw);
284                 if (lc == NULL)
285                         lc = login_getclassbyname(NULL, authctxt->pw);
286                 if (!auth_hostok(lc, from_host, from_ip)) {
287                         logit("Denied connection for %.200s from %.200s [%.200s].",
288                             authctxt->pw->pw_name, from_host, from_ip);
289                         packet_disconnect("Sorry, you are not allowed to connect.");
290                 }
291                 if (!auth_timeok(lc, time(NULL))) {
292                         logit("LOGIN %.200s REFUSED (TIME) FROM %.200s",
293                             authctxt->pw->pw_name, from_host);
294                         packet_disconnect("Logins not available right now.");
295                 }
296                 login_close(lc);
297                 lc = NULL;
298         }
299 #endif  /* HAVE_LOGIN_CAP */
300
301         /* reset state */
302         auth2_challenge_stop(authctxt);
303 #ifdef JPAKE
304         auth2_jpake_stop(authctxt);
305 #endif
306
307 #ifdef GSSAPI
308         /* XXX move to auth2_gssapi_stop() */
309         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
310         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
311 #endif
312
313         authctxt->postponed = 0;
314         authctxt->server_caused_failure = 0;
315
316         /* try to authenticate user */
317         m = authmethod_lookup(method);
318         if (m != NULL && authctxt->failures < options.max_authtries) {
319                 debug2("input_userauth_request: try method %s", method);
320                 authenticated = m->userauth(authctxt);
321         }
322         userauth_finish(authctxt, authenticated, method);
323
324         xfree(service);
325         xfree(user);
326         xfree(method);
327 }
328
329 void
330 userauth_finish(Authctxt *authctxt, int authenticated, char *method)
331 {
332         char *methods;
333
334         if (!authctxt->valid && authenticated)
335                 fatal("INTERNAL ERROR: authenticated invalid user %s",
336                     authctxt->user);
337
338         /* Special handling for root */
339         if (authenticated && authctxt->pw->pw_uid == 0 &&
340             !auth_root_allowed(method)) {
341                 authenticated = 0;
342 #ifdef SSH_AUDIT_EVENTS
343                 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
344 #endif
345         }
346
347 #ifdef USE_PAM
348         if (options.use_pam && authenticated) {
349                 if (!PRIVSEP(do_pam_account())) {
350                         /* if PAM returned a message, send it to the user */
351                         if (buffer_len(&loginmsg) > 0) {
352                                 buffer_append(&loginmsg, "\0", 1);
353                                 userauth_send_banner(buffer_ptr(&loginmsg));
354                                 packet_write_wait();
355                         }
356                         fatal("Access denied for user %s by PAM account "
357                             "configuration", authctxt->user);
358                 }
359         }
360 #endif
361
362 #ifdef _UNICOS
363         if (authenticated && cray_access_denied(authctxt->user)) {
364                 authenticated = 0;
365                 fatal("Access denied for user %s.",authctxt->user);
366         }
367 #endif /* _UNICOS */
368
369         /* Log before sending the reply */
370         auth_log(authctxt, authenticated, method, " ssh2");
371
372         if (authctxt->postponed)
373                 return;
374
375         /* XXX todo: check if multiple auth methods are needed */
376         if (authenticated == 1) {
377                 /* turn off userauth */
378                 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
379                 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
380                 packet_send();
381                 packet_write_wait();
382                 /* now we can break out */
383                 authctxt->success = 1;
384         } else {
385
386                 /* Allow initial try of "none" auth without failure penalty */
387                 if (!authctxt->server_caused_failure &&
388                     (authctxt->attempt > 1 || strcmp(method, "none") != 0))
389                         authctxt->failures++;
390                 if (authctxt->failures >= options.max_authtries) {
391 #ifdef SSH_AUDIT_EVENTS
392                         PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
393 #endif
394                         packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
395                 }
396                 methods = authmethods_get();
397                 packet_start(SSH2_MSG_USERAUTH_FAILURE);
398                 packet_put_cstring(methods);
399                 packet_put_char(0);     /* XXX partial success, unused */
400                 packet_send();
401                 packet_write_wait();
402                 xfree(methods);
403         }
404 }
405
406 static char *
407 authmethods_get(void)
408 {
409         Buffer b;
410         char *list;
411         int i;
412
413         buffer_init(&b);
414         for (i = 0; authmethods[i] != NULL; i++) {
415                 if (strcmp(authmethods[i]->name, "none") == 0)
416                         continue;
417                 if (authmethods[i]->enabled != NULL &&
418                     *(authmethods[i]->enabled) != 0) {
419                         if (buffer_len(&b) > 0)
420                                 buffer_append(&b, ",", 1);
421                         buffer_append(&b, authmethods[i]->name,
422                             strlen(authmethods[i]->name));
423                 }
424         }
425         buffer_append(&b, "\0", 1);
426         list = xstrdup(buffer_ptr(&b));
427         buffer_free(&b);
428         return list;
429 }
430
431 static Authmethod *
432 authmethod_lookup(const char *name)
433 {
434         int i;
435
436         if (name != NULL)
437                 for (i = 0; authmethods[i] != NULL; i++)
438                         if (authmethods[i]->enabled != NULL &&
439                             *(authmethods[i]->enabled) != 0 &&
440                             strcmp(name, authmethods[i]->name) == 0)
441                                 return authmethods[i];
442         debug2("Unrecognized authentication method name: %s",
443             name ? name : "NULL");
444         return NULL;
445 }
446