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 "blocklist_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 BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_OK,
293 "Authenticated");
294 }
295
296 if ((extra = format_method_key(authctxt)) == NULL) {
297 if (authctxt->auth_method_info != NULL)
298 extra = xstrdup(authctxt->auth_method_info);
299 }
300
301 do_log2(level, "%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
302 authmsg,
303 method,
304 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
305 authctxt->valid ? "" : "invalid user ",
306 authctxt->user,
307 ssh_remote_ipaddr(ssh),
308 ssh_remote_port(ssh),
309 extra != NULL ? ": " : "",
310 extra != NULL ? extra : "");
311
312 free(extra);
313
314 #if defined(CUSTOM_FAILED_LOGIN) || defined(SSH_AUDIT_EVENTS)
315 if (authenticated == 0 && !(authctxt->postponed || partial)) {
316 /* Log failed login attempt */
317 # ifdef CUSTOM_FAILED_LOGIN
318 if (strcmp(method, "password") == 0 ||
319 strncmp(method, "keyboard-interactive", 20) == 0 ||
320 strcmp(method, "challenge-response") == 0)
321 record_failed_login(ssh, authctxt->user,
322 auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
323 # endif
324 # ifdef SSH_AUDIT_EVENTS
325 audit_event(ssh, audit_classify_auth(method));
326 # endif
327 }
328 #endif
329 #if defined(CUSTOM_FAILED_LOGIN) && defined(WITH_AIXAUTHENTICATE)
330 if (authenticated)
331 sys_auth_record_login(authctxt->user,
332 auth_get_canonical_hostname(ssh, options.use_dns), "ssh",
333 loginmsg);
334 #endif
335 }
336
337 void
auth_maxtries_exceeded(struct ssh * ssh)338 auth_maxtries_exceeded(struct ssh *ssh)
339 {
340 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
341
342 BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_FAIL, "Maximum attempts exceeded");
343 error("maximum authentication attempts exceeded for "
344 "%s%.100s from %.200s port %d ssh2",
345 authctxt->valid ? "" : "invalid user ",
346 authctxt->user,
347 ssh_remote_ipaddr(ssh),
348 ssh_remote_port(ssh));
349 ssh_packet_disconnect(ssh, "Too many authentication failures");
350 /* NOTREACHED */
351 }
352
353 /*
354 * Check whether root logins are disallowed.
355 */
356 int
auth_root_allowed(struct ssh * ssh,const char * method)357 auth_root_allowed(struct ssh *ssh, const char *method)
358 {
359 switch (options.permit_root_login) {
360 case PERMIT_YES:
361 return 1;
362 case PERMIT_NO_PASSWD:
363 if (strcmp(method, "publickey") == 0 ||
364 strcmp(method, "hostbased") == 0 ||
365 strcmp(method, "gssapi-with-mic") == 0)
366 return 1;
367 break;
368 case PERMIT_FORCED_ONLY:
369 if (auth_opts->force_command != NULL) {
370 logit("Root login accepted for forced command.");
371 return 1;
372 }
373 break;
374 }
375 logit("ROOT LOGIN REFUSED FROM %.200s port %d",
376 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
377 return 0;
378 }
379
380
381 /*
382 * Given a template and a passwd structure, build a filename
383 * by substituting % tokenised options. Currently, %% becomes '%',
384 * %h becomes the home directory and %u the username.
385 *
386 * This returns a buffer allocated by xmalloc.
387 */
388 char *
expand_authorized_keys(const char * filename,struct passwd * pw)389 expand_authorized_keys(const char *filename, struct passwd *pw)
390 {
391 char *file, uidstr[32], ret[PATH_MAX];
392 int i;
393
394 snprintf(uidstr, sizeof(uidstr), "%llu",
395 (unsigned long long)pw->pw_uid);
396 file = percent_expand(filename, "h", pw->pw_dir,
397 "u", pw->pw_name, "U", uidstr, (char *)NULL);
398
399 /*
400 * Ensure that filename starts anchored. If not, be backward
401 * compatible and prepend the '%h/'
402 */
403 if (path_absolute(file))
404 return (file);
405
406 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
407 if (i < 0 || (size_t)i >= sizeof(ret))
408 fatal("expand_authorized_keys: path too long");
409 free(file);
410 return (xstrdup(ret));
411 }
412
413 char *
authorized_principals_file(struct passwd * pw)414 authorized_principals_file(struct passwd *pw)
415 {
416 if (options.authorized_principals_file == NULL)
417 return NULL;
418 return expand_authorized_keys(options.authorized_principals_file, pw);
419 }
420
421 /* return ok if key exists in sysfile or userfile */
422 HostStatus
check_key_in_hostfiles(struct passwd * pw,struct sshkey * key,const char * host,const char * sysfile,const char * userfile)423 check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
424 const char *sysfile, const char *userfile)
425 {
426 char *user_hostfile;
427 struct stat st;
428 HostStatus host_status;
429 struct hostkeys *hostkeys;
430 const struct hostkey_entry *found;
431
432 hostkeys = init_hostkeys();
433 load_hostkeys(hostkeys, host, sysfile, 0);
434 if (userfile != NULL) {
435 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
436 if (options.strict_modes &&
437 (stat(user_hostfile, &st) == 0) &&
438 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
439 (st.st_mode & 022) != 0)) {
440 logit("Authentication refused for %.100s: "
441 "bad owner or modes for %.200s",
442 pw->pw_name, user_hostfile);
443 auth_debug_add("Ignored %.200s: bad ownership or modes",
444 user_hostfile);
445 } else {
446 temporarily_use_uid(pw);
447 load_hostkeys(hostkeys, host, user_hostfile, 0);
448 restore_uid();
449 }
450 free(user_hostfile);
451 }
452 host_status = check_key_in_hostkeys(hostkeys, key, &found);
453 if (host_status == HOST_REVOKED)
454 error("WARNING: revoked key for %s attempted authentication",
455 host);
456 else if (host_status == HOST_OK)
457 debug_f("key for %s found at %s:%ld",
458 found->host, found->file, found->line);
459 else
460 debug_f("key for host %s not found", host);
461
462 free_hostkeys(hostkeys);
463
464 return host_status;
465 }
466
467 struct passwd *
getpwnamallow(struct ssh * ssh,const char * user)468 getpwnamallow(struct ssh *ssh, const char *user)
469 {
470 #ifdef HAVE_LOGIN_CAP
471 extern login_cap_t *lc;
472 #ifdef HAVE_AUTH_HOSTOK
473 const char *from_host, *from_ip;
474 #endif
475 #ifdef BSD_AUTH
476 auth_session_t *as;
477 #endif
478 #endif
479 struct passwd *pw;
480 struct connection_info *ci;
481 u_int i;
482
483 ci = server_get_connection_info(ssh, 1, options.use_dns);
484 ci->user = user;
485 ci->user_invalid = getpwnam(user) == NULL;
486 parse_server_match_config(&options, &includes, ci);
487 log_change_level(options.log_level);
488 log_verbose_reset();
489 for (i = 0; i < options.num_log_verbose; i++)
490 log_verbose_add(options.log_verbose[i]);
491 server_process_permitopen(ssh);
492
493 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
494 aix_setauthdb(user);
495 #endif
496
497 pw = getpwnam(user);
498
499 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
500 aix_restoreauthdb();
501 #endif
502 if (pw == NULL) {
503 BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_FAIL, "Invalid user");
504 logit("Invalid user %.100s from %.100s port %d",
505 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
506 #ifdef CUSTOM_FAILED_LOGIN
507 record_failed_login(ssh, user,
508 auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
509 #endif
510 #ifdef SSH_AUDIT_EVENTS
511 audit_event(ssh, SSH_INVALID_USER);
512 #endif /* SSH_AUDIT_EVENTS */
513 return (NULL);
514 }
515 if (!allowed_user(ssh, pw))
516 return (NULL);
517 #ifdef HAVE_LOGIN_CAP
518 if ((lc = login_getpwclass(pw)) == NULL) {
519 debug("unable to get login class: %s", user);
520 return (NULL);
521 }
522 #ifdef HAVE_AUTH_HOSTOK
523 from_host = auth_get_canonical_hostname(ssh, options.use_dns);
524 from_ip = ssh_remote_ipaddr(ssh);
525 if (!auth_hostok(lc, from_host, from_ip)) {
526 debug("Denied connection for %.200s from %.200s [%.200s].",
527 pw->pw_name, from_host, from_ip);
528 return (NULL);
529 }
530 #endif /* HAVE_AUTH_HOSTOK */
531 #ifdef HAVE_AUTH_TIMEOK
532 if (!auth_timeok(lc, time(NULL))) {
533 debug("LOGIN %.200s REFUSED (TIME)", pw->pw_name);
534 return (NULL);
535 }
536 #endif /* HAVE_AUTH_TIMEOK */
537 #ifdef BSD_AUTH
538 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
539 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
540 debug("Approval failure for %s", user);
541 pw = NULL;
542 }
543 if (as != NULL)
544 auth_close(as);
545 #endif
546 #endif
547 if (pw != NULL)
548 return (pwcopy(pw));
549 return (NULL);
550 }
551
552 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
553 int
auth_key_is_revoked(struct sshkey * key)554 auth_key_is_revoked(struct sshkey *key)
555 {
556 char *fp = NULL;
557 int r;
558
559 if (options.revoked_keys_file == NULL)
560 return 0;
561 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
562 SSH_FP_DEFAULT)) == NULL) {
563 r = SSH_ERR_ALLOC_FAIL;
564 error_fr(r, "fingerprint key");
565 goto out;
566 }
567
568 r = sshkey_check_revoked(key, options.revoked_keys_file);
569 switch (r) {
570 case 0:
571 break; /* not revoked */
572 case SSH_ERR_KEY_REVOKED:
573 error("Authentication key %s %s revoked by file %s",
574 sshkey_type(key), fp, options.revoked_keys_file);
575 goto out;
576 default:
577 error_r(r, "Error checking authentication key %s %s in "
578 "revoked keys file %s", sshkey_type(key), fp,
579 options.revoked_keys_file);
580 goto out;
581 }
582
583 /* Success */
584 r = 0;
585
586 out:
587 free(fp);
588 return r == 0 ? 0 : 1;
589 }
590
591 void
auth_debug_add(const char * fmt,...)592 auth_debug_add(const char *fmt,...)
593 {
594 char buf[1024];
595 va_list args;
596 int r;
597
598 va_start(args, fmt);
599 vsnprintf(buf, sizeof(buf), fmt, args);
600 va_end(args);
601 debug3("%s", buf);
602 if (auth_debug != NULL)
603 if ((r = sshbuf_put_cstring(auth_debug, buf)) != 0)
604 fatal_fr(r, "sshbuf_put_cstring");
605 }
606
607 void
auth_debug_send(struct ssh * ssh)608 auth_debug_send(struct ssh *ssh)
609 {
610 char *msg;
611 int r;
612
613 if (auth_debug == NULL)
614 return;
615 while (sshbuf_len(auth_debug) != 0) {
616 if ((r = sshbuf_get_cstring(auth_debug, &msg, NULL)) != 0)
617 fatal_fr(r, "sshbuf_get_cstring");
618 ssh_packet_send_debug(ssh, "%s", msg);
619 free(msg);
620 }
621 }
622
623 void
auth_debug_reset(void)624 auth_debug_reset(void)
625 {
626 if (auth_debug != NULL)
627 sshbuf_reset(auth_debug);
628 else if ((auth_debug = sshbuf_new()) == NULL)
629 fatal_f("sshbuf_new failed");
630 }
631
632 struct passwd *
fakepw(void)633 fakepw(void)
634 {
635 static int done = 0;
636 static struct passwd fake;
637 const char hashchars[] = "./ABCDEFGHIJKLMNOPQRSTUVWXYZ"
638 "abcdefghijklmnopqrstuvwxyz0123456789"; /* from bcrypt.c */
639 char *cp;
640
641 if (done)
642 return (&fake);
643
644 memset(&fake, 0, sizeof(fake));
645 fake.pw_name = "NOUSER";
646 fake.pw_passwd = xstrdup("$2a$10$"
647 "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
648 for (cp = fake.pw_passwd + 7; *cp != '\0'; cp++)
649 *cp = hashchars[arc4random_uniform(sizeof(hashchars) - 1)];
650 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
651 fake.pw_gecos = "NOUSER";
652 #endif
653 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
654 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
655 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
656 fake.pw_class = "";
657 #endif
658 fake.pw_dir = "/nonexist";
659 fake.pw_shell = "/nonexist";
660 done = 1;
661
662 return (&fake);
663 }
664
665 /*
666 * Return the canonical name of the host in the other side of the current
667 * connection. The host name is cached, so it is efficient to call this
668 * several times.
669 */
670
671 const char *
auth_get_canonical_hostname(struct ssh * ssh,int use_dns)672 auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
673 {
674 static char *dnsname;
675
676 if (!use_dns)
677 return ssh_remote_ipaddr(ssh);
678 if (dnsname != NULL)
679 return dnsname;
680 dnsname = ssh_remote_hostname(ssh);
681 return dnsname;
682 }
683
684 /* These functions link key/cert options to the auth framework */
685
686 /* Log sshauthopt options locally and (optionally) for remote transmission */
687 void
auth_log_authopts(const char * loc,const struct sshauthopt * opts,int do_remote)688 auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote)
689 {
690 int do_env = options.permit_user_env && opts->nenv > 0;
691 int do_permitopen = opts->npermitopen > 0 &&
692 (options.allow_tcp_forwarding & FORWARD_LOCAL) != 0;
693 int do_permitlisten = opts->npermitlisten > 0 &&
694 (options.allow_tcp_forwarding & FORWARD_REMOTE) != 0;
695 size_t i;
696 char msg[1024], buf[64];
697
698 snprintf(buf, sizeof(buf), "%d", opts->force_tun_device);
699 /* Try to keep this alphabetically sorted */
700 snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
701 opts->permit_agent_forwarding_flag ? " agent-forwarding" : "",
702 opts->force_command == NULL ? "" : " command",
703 do_env ? " environment" : "",
704 opts->valid_before == 0 ? "" : "expires",
705 opts->no_require_user_presence ? " no-touch-required" : "",
706 do_permitopen ? " permitopen" : "",
707 do_permitlisten ? " permitlisten" : "",
708 opts->permit_port_forwarding_flag ? " port-forwarding" : "",
709 opts->cert_principals == NULL ? "" : " principals",
710 opts->permit_pty_flag ? " pty" : "",
711 opts->require_verify ? " uv" : "",
712 opts->force_tun_device == -1 ? "" : " tun=",
713 opts->force_tun_device == -1 ? "" : buf,
714 opts->permit_user_rc ? " user-rc" : "",
715 opts->permit_x11_forwarding_flag ? " x11-forwarding" : "");
716
717 debug("%s: %s", loc, msg);
718 if (do_remote)
719 auth_debug_add("%s: %s", loc, msg);
720
721 if (options.permit_user_env) {
722 for (i = 0; i < opts->nenv; i++) {
723 debug("%s: environment: %s", loc, opts->env[i]);
724 if (do_remote) {
725 auth_debug_add("%s: environment: %s",
726 loc, opts->env[i]);
727 }
728 }
729 }
730
731 /* Go into a little more details for the local logs. */
732 if (opts->valid_before != 0) {
733 format_absolute_time(opts->valid_before, buf, sizeof(buf));
734 debug("%s: expires at %s", loc, buf);
735 }
736 if (opts->cert_principals != NULL) {
737 debug("%s: authorized principals: \"%s\"",
738 loc, opts->cert_principals);
739 }
740 if (opts->force_command != NULL)
741 debug("%s: forced command: \"%s\"", loc, opts->force_command);
742 if (do_permitopen) {
743 for (i = 0; i < opts->npermitopen; i++) {
744 debug("%s: permitted open: %s",
745 loc, opts->permitopen[i]);
746 }
747 }
748 if (do_permitlisten) {
749 for (i = 0; i < opts->npermitlisten; i++) {
750 debug("%s: permitted listen: %s",
751 loc, opts->permitlisten[i]);
752 }
753 }
754 }
755
756 /* Activate a new set of key/cert options; merging with what is there. */
757 int
auth_activate_options(struct ssh * ssh,struct sshauthopt * opts)758 auth_activate_options(struct ssh *ssh, struct sshauthopt *opts)
759 {
760 struct sshauthopt *old = auth_opts;
761 const char *emsg = NULL;
762
763 debug_f("setting new authentication options");
764 if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) {
765 error("Inconsistent authentication options: %s", emsg);
766 return -1;
767 }
768 return 0;
769 }
770
771 /* Disable forwarding, etc for the session */
772 void
auth_restrict_session(struct ssh * ssh)773 auth_restrict_session(struct ssh *ssh)
774 {
775 struct sshauthopt *restricted;
776
777 debug_f("restricting session");
778
779 /* A blank sshauthopt defaults to permitting nothing */
780 if ((restricted = sshauthopt_new()) == NULL)
781 fatal_f("sshauthopt_new failed");
782 restricted->permit_pty_flag = 1;
783 restricted->restricted = 1;
784
785 if (auth_activate_options(ssh, restricted) != 0)
786 fatal_f("failed to restrict session");
787 sshauthopt_free(restricted);
788 }
789