1 /* $OpenBSD: auth.c,v 1.162 2024/09/15 01:18:26 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/socket.h>
31 #include <sys/wait.h>
32
33 #include <netinet/in.h>
34
35 #include <stdlib.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #ifdef HAVE_PATHS_H
39 # include <paths.h>
40 #endif
41 #include <pwd.h>
42 #ifdef HAVE_LOGIN_H
43 #include <login.h>
44 #endif
45 #ifdef USE_SHADOW
46 #include <shadow.h>
47 #endif
48 #include <stdarg.h>
49 #include <stdio.h>
50 #include <string.h>
51 #include <unistd.h>
52 #include <limits.h>
53 #include <netdb.h>
54 #include <time.h>
55
56 #include "xmalloc.h"
57 #include "match.h"
58 #include "groupaccess.h"
59 #include "log.h"
60 #include "sshbuf.h"
61 #include "misc.h"
62 #include "servconf.h"
63 #include "sshkey.h"
64 #include "hostfile.h"
65 #include "auth.h"
66 #include "auth-options.h"
67 #include "canohost.h"
68 #include "uidswap.h"
69 #include "packet.h"
70 #include "loginrec.h"
71 #ifdef GSSAPI
72 #include "ssh-gss.h"
73 #endif
74 #include "authfile.h"
75 #include "monitor_wrap.h"
76 #include "ssherr.h"
77 #include "channels.h"
78 #include "blacklist_client.h"
79
80 /* import */
81 extern ServerOptions options;
82 extern struct include_list includes;
83 extern struct sshbuf *loginmsg;
84 extern struct passwd *privsep_pw;
85 extern struct sshauthopt *auth_opts;
86
87 /* Debugging messages */
88 static struct sshbuf *auth_debug;
89
90 /*
91 * Check if the user is allowed to log in via ssh. If user is listed
92 * in DenyUsers or one of user's groups is listed in DenyGroups, false
93 * will be returned. If AllowUsers isn't empty and user isn't listed
94 * there, or if AllowGroups isn't empty and one of user's groups isn't
95 * listed there, false will be returned.
96 * If the user's shell is not executable, false will be returned.
97 * Otherwise true is returned.
98 */
99 int
allowed_user(struct ssh * ssh,struct passwd * pw)100 allowed_user(struct ssh *ssh, struct passwd * pw)
101 {
102 struct stat st;
103 const char *hostname = NULL, *ipaddr = NULL;
104 u_int i;
105 int r;
106
107 /* Shouldn't be called if pw is NULL, but better safe than sorry... */
108 if (!pw || !pw->pw_name)
109 return 0;
110
111 if (!options.use_pam && platform_locked_account(pw)) {
112 logit("User %.100s not allowed because account is locked",
113 pw->pw_name);
114 return 0;
115 }
116
117 /*
118 * Deny if shell does not exist or is not executable unless we
119 * are chrooting.
120 */
121 if (options.chroot_directory == NULL ||
122 strcasecmp(options.chroot_directory, "none") == 0) {
123 char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
124 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
125
126 if (stat(shell, &st) == -1) {
127 logit("User %.100s not allowed because shell %.100s "
128 "does not exist", pw->pw_name, shell);
129 free(shell);
130 return 0;
131 }
132 if (S_ISREG(st.st_mode) == 0 ||
133 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
134 logit("User %.100s not allowed because shell %.100s "
135 "is not executable", pw->pw_name, shell);
136 free(shell);
137 return 0;
138 }
139 free(shell);
140 }
141
142 if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
143 options.num_deny_groups > 0 || options.num_allow_groups > 0) {
144 hostname = auth_get_canonical_hostname(ssh, options.use_dns);
145 ipaddr = ssh_remote_ipaddr(ssh);
146 }
147
148 /* Return false if user is listed in DenyUsers */
149 if (options.num_deny_users > 0) {
150 for (i = 0; i < options.num_deny_users; i++) {
151 r = match_user(pw->pw_name, hostname, ipaddr,
152 options.deny_users[i]);
153 if (r < 0) {
154 fatal("Invalid DenyUsers pattern \"%.100s\"",
155 options.deny_users[i]);
156 } else if (r != 0) {
157 logit("User %.100s from %.100s not allowed "
158 "because listed in DenyUsers",
159 pw->pw_name, hostname);
160 return 0;
161 }
162 }
163 }
164 /* Return false if AllowUsers isn't empty and user isn't listed there */
165 if (options.num_allow_users > 0) {
166 for (i = 0; i < options.num_allow_users; i++) {
167 r = match_user(pw->pw_name, hostname, ipaddr,
168 options.allow_users[i]);
169 if (r < 0) {
170 fatal("Invalid AllowUsers pattern \"%.100s\"",
171 options.allow_users[i]);
172 } else if (r == 1)
173 break;
174 }
175 /* i < options.num_allow_users iff we break for loop */
176 if (i >= options.num_allow_users) {
177 logit("User %.100s from %.100s not allowed because "
178 "not listed in AllowUsers", pw->pw_name, hostname);
179 return 0;
180 }
181 }
182 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
183 /* Get the user's group access list (primary and supplementary) */
184 if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
185 logit("User %.100s from %.100s not allowed because "
186 "not in any group", pw->pw_name, hostname);
187 return 0;
188 }
189
190 /* Return false if one of user's groups is listed in DenyGroups */
191 if (options.num_deny_groups > 0)
192 if (ga_match(options.deny_groups,
193 options.num_deny_groups)) {
194 ga_free();
195 logit("User %.100s from %.100s not allowed "
196 "because a group is listed in DenyGroups",
197 pw->pw_name, hostname);
198 return 0;
199 }
200 /*
201 * Return false if AllowGroups isn't empty and one of user's groups
202 * isn't listed there
203 */
204 if (options.num_allow_groups > 0)
205 if (!ga_match(options.allow_groups,
206 options.num_allow_groups)) {
207 ga_free();
208 logit("User %.100s from %.100s not allowed "
209 "because none of user's groups are listed "
210 "in AllowGroups", pw->pw_name, hostname);
211 return 0;
212 }
213 ga_free();
214 }
215
216 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
217 if (!sys_auth_allowed_user(pw, loginmsg))
218 return 0;
219 #endif
220
221 /* We found no reason not to let this user try to log on... */
222 return 1;
223 }
224
225 /*
226 * Formats any key left in authctxt->auth_method_key for inclusion in
227 * auth_log()'s message. Also includes authxtct->auth_method_info if present.
228 */
229 static char *
format_method_key(Authctxt * authctxt)230 format_method_key(Authctxt *authctxt)
231 {
232 const struct sshkey *key = authctxt->auth_method_key;
233 const char *methinfo = authctxt->auth_method_info;
234 char *fp, *cafp, *ret = NULL;
235
236 if (key == NULL)
237 return NULL;
238
239 if (sshkey_is_cert(key)) {
240 fp = sshkey_fingerprint(key,
241 options.fingerprint_hash, SSH_FP_DEFAULT);
242 cafp = sshkey_fingerprint(key->cert->signature_key,
243 options.fingerprint_hash, SSH_FP_DEFAULT);
244 xasprintf(&ret, "%s %s ID %s (serial %llu) CA %s %s%s%s",
245 sshkey_type(key), fp == NULL ? "(null)" : fp,
246 key->cert->key_id,
247 (unsigned long long)key->cert->serial,
248 sshkey_type(key->cert->signature_key),
249 cafp == NULL ? "(null)" : cafp,
250 methinfo == NULL ? "" : ", ",
251 methinfo == NULL ? "" : methinfo);
252 free(fp);
253 free(cafp);
254 } else {
255 fp = sshkey_fingerprint(key, options.fingerprint_hash,
256 SSH_FP_DEFAULT);
257 xasprintf(&ret, "%s %s%s%s", sshkey_type(key),
258 fp == NULL ? "(null)" : fp,
259 methinfo == NULL ? "" : ", ",
260 methinfo == NULL ? "" : methinfo);
261 free(fp);
262 }
263 return ret;
264 }
265
266 void
auth_log(struct ssh * ssh,int authenticated,int partial,const char * method,const char * submethod)267 auth_log(struct ssh *ssh, int authenticated, int partial,
268 const char *method, const char *submethod)
269 {
270 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
271 int level = SYSLOG_LEVEL_VERBOSE;
272 const char *authmsg;
273 char *extra = NULL;
274
275 if (!mm_is_monitor() && !authctxt->postponed)
276 return;
277
278 /* Raise logging level */
279 if (authenticated == 1 ||
280 !authctxt->valid ||
281 authctxt->failures >= options.max_authtries / 2 ||
282 strcmp(method, "password") == 0)
283 level = SYSLOG_LEVEL_INFO;
284
285 if (authctxt->postponed)
286 authmsg = "Postponed";
287 else if (partial)
288 authmsg = "Partial";
289 else {
290 authmsg = authenticated ? "Accepted" : "Failed";
291 if (authenticated)
292 BLACKLIST_NOTIFY(ssh, BLACKLIST_AUTH_OK, "ssh");
293 }
294
295 if ((extra = format_method_key(authctxt)) == NULL) {
296 if (authctxt->auth_method_info != NULL)
297 extra = xstrdup(authctxt->auth_method_info);
298 }
299
300 do_log2(level, "%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
301 authmsg,
302 method,
303 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
304 authctxt->valid ? "" : "invalid user ",
305 authctxt->user,
306 ssh_remote_ipaddr(ssh),
307 ssh_remote_port(ssh),
308 extra != NULL ? ": " : "",
309 extra != NULL ? extra : "");
310
311 free(extra);
312
313 #if defined(CUSTOM_FAILED_LOGIN) || defined(SSH_AUDIT_EVENTS)
314 if (authenticated == 0 && !(authctxt->postponed || partial)) {
315 /* Log failed login attempt */
316 # ifdef CUSTOM_FAILED_LOGIN
317 if (strcmp(method, "password") == 0 ||
318 strncmp(method, "keyboard-interactive", 20) == 0 ||
319 strcmp(method, "challenge-response") == 0)
320 record_failed_login(ssh, authctxt->user,
321 auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
322 # endif
323 # ifdef SSH_AUDIT_EVENTS
324 audit_event(ssh, audit_classify_auth(method));
325 # endif
326 }
327 #endif
328 #if defined(CUSTOM_FAILED_LOGIN) && defined(WITH_AIXAUTHENTICATE)
329 if (authenticated)
330 sys_auth_record_login(authctxt->user,
331 auth_get_canonical_hostname(ssh, options.use_dns), "ssh",
332 loginmsg);
333 #endif
334 }
335
336 void
auth_maxtries_exceeded(struct ssh * ssh)337 auth_maxtries_exceeded(struct ssh *ssh)
338 {
339 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
340
341 error("maximum authentication attempts exceeded for "
342 "%s%.100s from %.200s port %d ssh2",
343 authctxt->valid ? "" : "invalid user ",
344 authctxt->user,
345 ssh_remote_ipaddr(ssh),
346 ssh_remote_port(ssh));
347 ssh_packet_disconnect(ssh, "Too many authentication failures");
348 /* NOTREACHED */
349 }
350
351 /*
352 * Check whether root logins are disallowed.
353 */
354 int
auth_root_allowed(struct ssh * ssh,const char * method)355 auth_root_allowed(struct ssh *ssh, const char *method)
356 {
357 switch (options.permit_root_login) {
358 case PERMIT_YES:
359 return 1;
360 case PERMIT_NO_PASSWD:
361 if (strcmp(method, "publickey") == 0 ||
362 strcmp(method, "hostbased") == 0 ||
363 strcmp(method, "gssapi-with-mic") == 0)
364 return 1;
365 break;
366 case PERMIT_FORCED_ONLY:
367 if (auth_opts->force_command != NULL) {
368 logit("Root login accepted for forced command.");
369 return 1;
370 }
371 break;
372 }
373 logit("ROOT LOGIN REFUSED FROM %.200s port %d",
374 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
375 return 0;
376 }
377
378
379 /*
380 * Given a template and a passwd structure, build a filename
381 * by substituting % tokenised options. Currently, %% becomes '%',
382 * %h becomes the home directory and %u the username.
383 *
384 * This returns a buffer allocated by xmalloc.
385 */
386 char *
expand_authorized_keys(const char * filename,struct passwd * pw)387 expand_authorized_keys(const char *filename, struct passwd *pw)
388 {
389 char *file, uidstr[32], ret[PATH_MAX];
390 int i;
391
392 snprintf(uidstr, sizeof(uidstr), "%llu",
393 (unsigned long long)pw->pw_uid);
394 file = percent_expand(filename, "h", pw->pw_dir,
395 "u", pw->pw_name, "U", uidstr, (char *)NULL);
396
397 /*
398 * Ensure that filename starts anchored. If not, be backward
399 * compatible and prepend the '%h/'
400 */
401 if (path_absolute(file))
402 return (file);
403
404 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
405 if (i < 0 || (size_t)i >= sizeof(ret))
406 fatal("expand_authorized_keys: path too long");
407 free(file);
408 return (xstrdup(ret));
409 }
410
411 char *
authorized_principals_file(struct passwd * pw)412 authorized_principals_file(struct passwd *pw)
413 {
414 if (options.authorized_principals_file == NULL)
415 return NULL;
416 return expand_authorized_keys(options.authorized_principals_file, pw);
417 }
418
419 /* return ok if key exists in sysfile or userfile */
420 HostStatus
check_key_in_hostfiles(struct passwd * pw,struct sshkey * key,const char * host,const char * sysfile,const char * userfile)421 check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
422 const char *sysfile, const char *userfile)
423 {
424 char *user_hostfile;
425 struct stat st;
426 HostStatus host_status;
427 struct hostkeys *hostkeys;
428 const struct hostkey_entry *found;
429
430 hostkeys = init_hostkeys();
431 load_hostkeys(hostkeys, host, sysfile, 0);
432 if (userfile != NULL) {
433 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
434 if (options.strict_modes &&
435 (stat(user_hostfile, &st) == 0) &&
436 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
437 (st.st_mode & 022) != 0)) {
438 logit("Authentication refused for %.100s: "
439 "bad owner or modes for %.200s",
440 pw->pw_name, user_hostfile);
441 auth_debug_add("Ignored %.200s: bad ownership or modes",
442 user_hostfile);
443 } else {
444 temporarily_use_uid(pw);
445 load_hostkeys(hostkeys, host, user_hostfile, 0);
446 restore_uid();
447 }
448 free(user_hostfile);
449 }
450 host_status = check_key_in_hostkeys(hostkeys, key, &found);
451 if (host_status == HOST_REVOKED)
452 error("WARNING: revoked key for %s attempted authentication",
453 host);
454 else if (host_status == HOST_OK)
455 debug_f("key for %s found at %s:%ld",
456 found->host, found->file, found->line);
457 else
458 debug_f("key for host %s not found", host);
459
460 free_hostkeys(hostkeys);
461
462 return host_status;
463 }
464
465 struct passwd *
getpwnamallow(struct ssh * ssh,const char * user)466 getpwnamallow(struct ssh *ssh, const char *user)
467 {
468 #ifdef HAVE_LOGIN_CAP
469 extern login_cap_t *lc;
470 #ifdef HAVE_AUTH_HOSTOK
471 const char *from_host, *from_ip;
472 #endif
473 #ifdef BSD_AUTH
474 auth_session_t *as;
475 #endif
476 #endif
477 struct passwd *pw;
478 struct connection_info *ci;
479 u_int i;
480
481 ci = server_get_connection_info(ssh, 1, options.use_dns);
482 ci->user = user;
483 ci->user_invalid = getpwnam(user) == NULL;
484 parse_server_match_config(&options, &includes, ci);
485 log_change_level(options.log_level);
486 log_verbose_reset();
487 for (i = 0; i < options.num_log_verbose; i++)
488 log_verbose_add(options.log_verbose[i]);
489 server_process_permitopen(ssh);
490
491 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
492 aix_setauthdb(user);
493 #endif
494
495 pw = getpwnam(user);
496
497 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
498 aix_restoreauthdb();
499 #endif
500 if (pw == NULL) {
501 BLACKLIST_NOTIFY(ssh, BLACKLIST_BAD_USER, user);
502 logit("Invalid user %.100s from %.100s port %d",
503 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
504 #ifdef CUSTOM_FAILED_LOGIN
505 record_failed_login(ssh, user,
506 auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
507 #endif
508 #ifdef SSH_AUDIT_EVENTS
509 audit_event(ssh, SSH_INVALID_USER);
510 #endif /* SSH_AUDIT_EVENTS */
511 return (NULL);
512 }
513 if (!allowed_user(ssh, pw))
514 return (NULL);
515 #ifdef HAVE_LOGIN_CAP
516 if ((lc = login_getpwclass(pw)) == NULL) {
517 debug("unable to get login class: %s", user);
518 return (NULL);
519 }
520 #ifdef HAVE_AUTH_HOSTOK
521 from_host = auth_get_canonical_hostname(ssh, options.use_dns);
522 from_ip = ssh_remote_ipaddr(ssh);
523 if (!auth_hostok(lc, from_host, from_ip)) {
524 debug("Denied connection for %.200s from %.200s [%.200s].",
525 pw->pw_name, from_host, from_ip);
526 return (NULL);
527 }
528 #endif /* HAVE_AUTH_HOSTOK */
529 #ifdef HAVE_AUTH_TIMEOK
530 if (!auth_timeok(lc, time(NULL))) {
531 debug("LOGIN %.200s REFUSED (TIME)", pw->pw_name);
532 return (NULL);
533 }
534 #endif /* HAVE_AUTH_TIMEOK */
535 #ifdef BSD_AUTH
536 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
537 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
538 debug("Approval failure for %s", user);
539 pw = NULL;
540 }
541 if (as != NULL)
542 auth_close(as);
543 #endif
544 #endif
545 if (pw != NULL)
546 return (pwcopy(pw));
547 return (NULL);
548 }
549
550 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
551 int
auth_key_is_revoked(struct sshkey * key)552 auth_key_is_revoked(struct sshkey *key)
553 {
554 char *fp = NULL;
555 int r;
556
557 if (options.revoked_keys_file == NULL)
558 return 0;
559 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
560 SSH_FP_DEFAULT)) == NULL) {
561 r = SSH_ERR_ALLOC_FAIL;
562 error_fr(r, "fingerprint key");
563 goto out;
564 }
565
566 r = sshkey_check_revoked(key, options.revoked_keys_file);
567 switch (r) {
568 case 0:
569 break; /* not revoked */
570 case SSH_ERR_KEY_REVOKED:
571 error("Authentication key %s %s revoked by file %s",
572 sshkey_type(key), fp, options.revoked_keys_file);
573 goto out;
574 default:
575 error_r(r, "Error checking authentication key %s %s in "
576 "revoked keys file %s", sshkey_type(key), fp,
577 options.revoked_keys_file);
578 goto out;
579 }
580
581 /* Success */
582 r = 0;
583
584 out:
585 free(fp);
586 return r == 0 ? 0 : 1;
587 }
588
589 void
auth_debug_add(const char * fmt,...)590 auth_debug_add(const char *fmt,...)
591 {
592 char buf[1024];
593 va_list args;
594 int r;
595
596 va_start(args, fmt);
597 vsnprintf(buf, sizeof(buf), fmt, args);
598 va_end(args);
599 debug3("%s", buf);
600 if (auth_debug != NULL)
601 if ((r = sshbuf_put_cstring(auth_debug, buf)) != 0)
602 fatal_fr(r, "sshbuf_put_cstring");
603 }
604
605 void
auth_debug_send(struct ssh * ssh)606 auth_debug_send(struct ssh *ssh)
607 {
608 char *msg;
609 int r;
610
611 if (auth_debug == NULL)
612 return;
613 while (sshbuf_len(auth_debug) != 0) {
614 if ((r = sshbuf_get_cstring(auth_debug, &msg, NULL)) != 0)
615 fatal_fr(r, "sshbuf_get_cstring");
616 ssh_packet_send_debug(ssh, "%s", msg);
617 free(msg);
618 }
619 }
620
621 void
auth_debug_reset(void)622 auth_debug_reset(void)
623 {
624 if (auth_debug != NULL)
625 sshbuf_reset(auth_debug);
626 else if ((auth_debug = sshbuf_new()) == NULL)
627 fatal_f("sshbuf_new failed");
628 }
629
630 struct passwd *
fakepw(void)631 fakepw(void)
632 {
633 static int done = 0;
634 static struct passwd fake;
635 const char hashchars[] = "./ABCDEFGHIJKLMNOPQRSTUVWXYZ"
636 "abcdefghijklmnopqrstuvwxyz0123456789"; /* from bcrypt.c */
637 char *cp;
638
639 if (done)
640 return (&fake);
641
642 memset(&fake, 0, sizeof(fake));
643 fake.pw_name = "NOUSER";
644 fake.pw_passwd = xstrdup("$2a$10$"
645 "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
646 for (cp = fake.pw_passwd + 7; *cp != '\0'; cp++)
647 *cp = hashchars[arc4random_uniform(sizeof(hashchars) - 1)];
648 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
649 fake.pw_gecos = "NOUSER";
650 #endif
651 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
652 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
653 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
654 fake.pw_class = "";
655 #endif
656 fake.pw_dir = "/nonexist";
657 fake.pw_shell = "/nonexist";
658 done = 1;
659
660 return (&fake);
661 }
662
663 /*
664 * Return the canonical name of the host in the other side of the current
665 * connection. The host name is cached, so it is efficient to call this
666 * several times.
667 */
668
669 const char *
auth_get_canonical_hostname(struct ssh * ssh,int use_dns)670 auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
671 {
672 static char *dnsname;
673
674 if (!use_dns)
675 return ssh_remote_ipaddr(ssh);
676 if (dnsname != NULL)
677 return dnsname;
678 dnsname = ssh_remote_hostname(ssh);
679 return dnsname;
680 }
681
682 /* These functions link key/cert options to the auth framework */
683
684 /* Log sshauthopt options locally and (optionally) for remote transmission */
685 void
auth_log_authopts(const char * loc,const struct sshauthopt * opts,int do_remote)686 auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote)
687 {
688 int do_env = options.permit_user_env && opts->nenv > 0;
689 int do_permitopen = opts->npermitopen > 0 &&
690 (options.allow_tcp_forwarding & FORWARD_LOCAL) != 0;
691 int do_permitlisten = opts->npermitlisten > 0 &&
692 (options.allow_tcp_forwarding & FORWARD_REMOTE) != 0;
693 size_t i;
694 char msg[1024], buf[64];
695
696 snprintf(buf, sizeof(buf), "%d", opts->force_tun_device);
697 /* Try to keep this alphabetically sorted */
698 snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
699 opts->permit_agent_forwarding_flag ? " agent-forwarding" : "",
700 opts->force_command == NULL ? "" : " command",
701 do_env ? " environment" : "",
702 opts->valid_before == 0 ? "" : "expires",
703 opts->no_require_user_presence ? " no-touch-required" : "",
704 do_permitopen ? " permitopen" : "",
705 do_permitlisten ? " permitlisten" : "",
706 opts->permit_port_forwarding_flag ? " port-forwarding" : "",
707 opts->cert_principals == NULL ? "" : " principals",
708 opts->permit_pty_flag ? " pty" : "",
709 opts->require_verify ? " uv" : "",
710 opts->force_tun_device == -1 ? "" : " tun=",
711 opts->force_tun_device == -1 ? "" : buf,
712 opts->permit_user_rc ? " user-rc" : "",
713 opts->permit_x11_forwarding_flag ? " x11-forwarding" : "");
714
715 debug("%s: %s", loc, msg);
716 if (do_remote)
717 auth_debug_add("%s: %s", loc, msg);
718
719 if (options.permit_user_env) {
720 for (i = 0; i < opts->nenv; i++) {
721 debug("%s: environment: %s", loc, opts->env[i]);
722 if (do_remote) {
723 auth_debug_add("%s: environment: %s",
724 loc, opts->env[i]);
725 }
726 }
727 }
728
729 /* Go into a little more details for the local logs. */
730 if (opts->valid_before != 0) {
731 format_absolute_time(opts->valid_before, buf, sizeof(buf));
732 debug("%s: expires at %s", loc, buf);
733 }
734 if (opts->cert_principals != NULL) {
735 debug("%s: authorized principals: \"%s\"",
736 loc, opts->cert_principals);
737 }
738 if (opts->force_command != NULL)
739 debug("%s: forced command: \"%s\"", loc, opts->force_command);
740 if (do_permitopen) {
741 for (i = 0; i < opts->npermitopen; i++) {
742 debug("%s: permitted open: %s",
743 loc, opts->permitopen[i]);
744 }
745 }
746 if (do_permitlisten) {
747 for (i = 0; i < opts->npermitlisten; i++) {
748 debug("%s: permitted listen: %s",
749 loc, opts->permitlisten[i]);
750 }
751 }
752 }
753
754 /* Activate a new set of key/cert options; merging with what is there. */
755 int
auth_activate_options(struct ssh * ssh,struct sshauthopt * opts)756 auth_activate_options(struct ssh *ssh, struct sshauthopt *opts)
757 {
758 struct sshauthopt *old = auth_opts;
759 const char *emsg = NULL;
760
761 debug_f("setting new authentication options");
762 if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) {
763 error("Inconsistent authentication options: %s", emsg);
764 return -1;
765 }
766 return 0;
767 }
768
769 /* Disable forwarding, etc for the session */
770 void
auth_restrict_session(struct ssh * ssh)771 auth_restrict_session(struct ssh *ssh)
772 {
773 struct sshauthopt *restricted;
774
775 debug_f("restricting session");
776
777 /* A blank sshauthopt defaults to permitting nothing */
778 if ((restricted = sshauthopt_new()) == NULL)
779 fatal_f("sshauthopt_new failed");
780 restricted->permit_pty_flag = 1;
781 restricted->restricted = 1;
782
783 if (auth_activate_options(ssh, restricted) != 0)
784 fatal_f("failed to restrict session");
785 sshauthopt_free(restricted);
786 }
787