Annotation of src/usr.bin/ssh/auth.c, Revision 1.160
1.160 ! dtucker 1: /* $OpenBSD: auth.c,v 1.159 2022/12/09 00:17:40 dtucker Exp $ */
1.1 markus 2: /*
1.19 deraadt 3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
1.9 deraadt 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.
1.1 markus 24: */
25:
1.62 stevesk 26: #include <sys/types.h>
27: #include <sys/stat.h>
1.114 djm 28: #include <sys/socket.h>
1.125 markus 29: #include <sys/wait.h>
1.22 markus 30:
1.140 djm 31: #include <stdlib.h>
1.70 stevesk 32: #include <errno.h>
1.79 dtucker 33: #include <fcntl.h>
1.77 djm 34: #include <login_cap.h>
1.61 stevesk 35: #include <paths.h>
1.68 stevesk 36: #include <pwd.h>
1.69 stevesk 37: #include <stdarg.h>
1.74 stevesk 38: #include <stdio.h>
1.72 stevesk 39: #include <string.h>
1.80 djm 40: #include <unistd.h>
1.109 deraadt 41: #include <limits.h>
1.114 djm 42: #include <netdb.h>
1.135 djm 43: #include <time.h>
1.1 markus 44:
45: #include "xmalloc.h"
1.13 markus 46: #include "match.h"
1.14 markus 47: #include "groupaccess.h"
48: #include "log.h"
1.131 markus 49: #include "sshbuf.h"
1.106 millert 50: #include "misc.h"
1.1 markus 51: #include "servconf.h"
1.131 markus 52: #include "sshkey.h"
1.75 deraadt 53: #include "hostfile.h"
1.2 markus 54: #include "auth.h"
1.13 markus 55: #include "auth-options.h"
1.14 markus 56: #include "canohost.h"
1.24 markus 57: #include "uidswap.h"
1.42 markus 58: #include "packet.h"
1.75 deraadt 59: #ifdef GSSAPI
60: #include "ssh-gss.h"
61: #endif
1.85 djm 62: #include "authfile.h"
1.67 dtucker 63: #include "monitor_wrap.h"
1.107 djm 64: #include "ssherr.h"
1.126 djm 65: #include "channels.h"
1.136 djm 66:
1.1 markus 67: /* import */
68: extern ServerOptions options;
1.146 djm 69: extern struct include_list includes;
1.67 dtucker 70: extern int use_privsep;
1.126 djm 71: extern struct sshauthopt *auth_opts;
1.1 markus 72:
1.42 markus 73: /* Debugging messages */
1.131 markus 74: static struct sshbuf *auth_debug;
1.42 markus 75:
1.1 markus 76: /*
1.12 markus 77: * Check if the user is allowed to log in via ssh. If user is listed
78: * in DenyUsers or one of user's groups is listed in DenyGroups, false
79: * will be returned. If AllowUsers isn't empty and user isn't listed
80: * there, or if AllowGroups isn't empty and one of user's groups isn't
81: * listed there, false will be returned.
1.1 markus 82: * If the user's shell is not executable, false will be returned.
1.4 markus 83: * Otherwise true is returned.
1.1 markus 84: */
1.5 markus 85: int
1.138 djm 86: allowed_user(struct ssh *ssh, struct passwd * pw)
1.1 markus 87: {
88: struct stat st;
1.35 markus 89: const char *hostname = NULL, *ipaddr = NULL;
1.117 djm 90: int r;
1.60 djm 91: u_int i;
1.1 markus 92:
93: /* Shouldn't be called if pw is NULL, but better safe than sorry... */
1.12 markus 94: if (!pw || !pw->pw_name)
1.1 markus 95: return 0;
96:
1.7 deraadt 97: /*
1.84 djm 98: * Deny if shell does not exist or is not executable unless we
99: * are chrooting.
1.7 deraadt 100: */
1.84 djm 101: if (options.chroot_directory == NULL ||
102: strcasecmp(options.chroot_directory, "none") == 0) {
103: char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
104: _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
105:
1.139 deraadt 106: if (stat(shell, &st) == -1) {
1.84 djm 107: logit("User %.100s not allowed because shell %.100s "
108: "does not exist", pw->pw_name, shell);
1.102 djm 109: free(shell);
1.84 djm 110: return 0;
111: }
112: if (S_ISREG(st.st_mode) == 0 ||
113: (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
114: logit("User %.100s not allowed because shell %.100s "
115: "is not executable", pw->pw_name, shell);
1.102 djm 116: free(shell);
1.84 djm 117: return 0;
118: }
1.102 djm 119: free(shell);
1.34 stevesk 120: }
1.1 markus 121:
1.58 dtucker 122: if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
123: options.num_deny_groups > 0 || options.num_allow_groups > 0) {
1.114 djm 124: hostname = auth_get_canonical_hostname(ssh, options.use_dns);
125: ipaddr = ssh_remote_ipaddr(ssh);
1.35 markus 126: }
127:
1.1 markus 128: /* Return false if user is listed in DenyUsers */
129: if (options.num_deny_users > 0) {
1.119 dtucker 130: for (i = 0; i < options.num_deny_users; i++) {
1.117 djm 131: r = match_user(pw->pw_name, hostname, ipaddr,
132: options.deny_users[i]);
133: if (r < 0) {
134: fatal("Invalid DenyUsers pattern \"%.100s\"",
135: options.deny_users[i]);
1.118 djm 136: } else if (r != 0) {
1.57 dtucker 137: logit("User %.100s from %.100s not allowed "
138: "because listed in DenyUsers",
139: pw->pw_name, hostname);
1.1 markus 140: return 0;
1.34 stevesk 141: }
1.119 dtucker 142: }
1.1 markus 143: }
144: /* Return false if AllowUsers isn't empty and user isn't listed there */
145: if (options.num_allow_users > 0) {
1.117 djm 146: for (i = 0; i < options.num_allow_users; i++) {
147: r = match_user(pw->pw_name, hostname, ipaddr,
148: options.allow_users[i]);
149: if (r < 0) {
150: fatal("Invalid AllowUsers pattern \"%.100s\"",
151: options.allow_users[i]);
152: } else if (r == 1)
1.1 markus 153: break;
1.117 djm 154: }
1.1 markus 155: /* i < options.num_allow_users iff we break for loop */
1.34 stevesk 156: if (i >= options.num_allow_users) {
1.57 dtucker 157: logit("User %.100s from %.100s not allowed because "
158: "not listed in AllowUsers", pw->pw_name, hostname);
1.1 markus 159: return 0;
1.34 stevesk 160: }
1.1 markus 161: }
162: if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
1.12 markus 163: /* Get the user's group access list (primary and supplementary) */
1.34 stevesk 164: if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
1.57 dtucker 165: logit("User %.100s from %.100s not allowed because "
166: "not in any group", pw->pw_name, hostname);
1.1 markus 167: return 0;
1.34 stevesk 168: }
1.1 markus 169:
1.12 markus 170: /* Return false if one of user's groups is listed in DenyGroups */
171: if (options.num_deny_groups > 0)
172: if (ga_match(options.deny_groups,
173: options.num_deny_groups)) {
174: ga_free();
1.57 dtucker 175: logit("User %.100s from %.100s not allowed "
176: "because a group is listed in DenyGroups",
177: pw->pw_name, hostname);
1.1 markus 178: return 0;
1.12 markus 179: }
1.1 markus 180: /*
1.12 markus 181: * Return false if AllowGroups isn't empty and one of user's groups
1.1 markus 182: * isn't listed there
183: */
1.12 markus 184: if (options.num_allow_groups > 0)
185: if (!ga_match(options.allow_groups,
186: options.num_allow_groups)) {
187: ga_free();
1.57 dtucker 188: logit("User %.100s from %.100s not allowed "
189: "because none of user's groups are listed "
190: "in AllowGroups", pw->pw_name, hostname);
1.1 markus 191: return 0;
1.12 markus 192: }
193: ga_free();
1.1 markus 194: }
195: /* We found no reason not to let this user try to log on... */
196: return 1;
1.13 markus 197: }
198:
1.122 djm 199: /*
200: * Formats any key left in authctxt->auth_method_key for inclusion in
201: * auth_log()'s message. Also includes authxtct->auth_method_info if present.
202: */
203: static char *
204: format_method_key(Authctxt *authctxt)
1.103 djm 205: {
1.122 djm 206: const struct sshkey *key = authctxt->auth_method_key;
207: const char *methinfo = authctxt->auth_method_info;
1.133 djm 208: char *fp, *cafp, *ret = NULL;
1.122 djm 209:
210: if (key == NULL)
211: return NULL;
212:
1.131 markus 213: if (sshkey_is_cert(key)) {
1.133 djm 214: fp = sshkey_fingerprint(key,
1.122 djm 215: options.fingerprint_hash, SSH_FP_DEFAULT);
1.133 djm 216: cafp = sshkey_fingerprint(key->cert->signature_key,
217: options.fingerprint_hash, SSH_FP_DEFAULT);
218: xasprintf(&ret, "%s %s ID %s (serial %llu) CA %s %s%s%s",
219: sshkey_type(key), fp == NULL ? "(null)" : fp,
220: key->cert->key_id,
1.122 djm 221: (unsigned long long)key->cert->serial,
222: sshkey_type(key->cert->signature_key),
1.133 djm 223: cafp == NULL ? "(null)" : cafp,
1.122 djm 224: methinfo == NULL ? "" : ", ",
225: methinfo == NULL ? "" : methinfo);
226: free(fp);
1.133 djm 227: free(cafp);
1.122 djm 228: } else {
229: fp = sshkey_fingerprint(key, options.fingerprint_hash,
230: SSH_FP_DEFAULT);
231: xasprintf(&ret, "%s %s%s%s", sshkey_type(key),
232: fp == NULL ? "(null)" : fp,
233: methinfo == NULL ? "" : ", ",
234: methinfo == NULL ? "" : methinfo);
235: free(fp);
236: }
237: return ret;
1.103 djm 238: }
239:
240: void
1.138 djm 241: auth_log(struct ssh *ssh, int authenticated, int partial,
1.103 djm 242: const char *method, const char *submethod)
1.13 markus 243: {
1.138 djm 244: Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1.133 djm 245: int level = SYSLOG_LEVEL_VERBOSE;
1.122 djm 246: const char *authmsg;
247: char *extra = NULL;
1.67 dtucker 248:
249: if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
250: return;
1.13 markus 251:
252: /* Raise logging level */
253: if (authenticated == 1 ||
254: !authctxt->valid ||
1.54 dtucker 255: authctxt->failures >= options.max_authtries / 2 ||
1.13 markus 256: strcmp(method, "password") == 0)
1.133 djm 257: level = SYSLOG_LEVEL_INFO;
1.13 markus 258:
259: if (authctxt->postponed)
260: authmsg = "Postponed";
1.98 djm 261: else if (partial)
262: authmsg = "Partial";
1.13 markus 263: else
264: authmsg = authenticated ? "Accepted" : "Failed";
265:
1.122 djm 266: if ((extra = format_method_key(authctxt)) == NULL) {
267: if (authctxt->auth_method_info != NULL)
268: extra = xstrdup(authctxt->auth_method_info);
269: }
270:
1.133 djm 271: do_log2(level, "%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
1.13 markus 272: authmsg,
273: method,
1.98 djm 274: submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
1.56 markus 275: authctxt->valid ? "" : "invalid user ",
1.29 markus 276: authctxt->user,
1.114 djm 277: ssh_remote_ipaddr(ssh),
278: ssh_remote_port(ssh),
1.122 djm 279: extra != NULL ? ": " : "",
280: extra != NULL ? extra : "");
281:
282: free(extra);
1.105 djm 283: }
284:
285: void
1.138 djm 286: auth_maxtries_exceeded(struct ssh *ssh)
1.105 djm 287: {
1.138 djm 288: Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1.114 djm 289:
1.110 djm 290: error("maximum authentication attempts exceeded for "
1.116 markus 291: "%s%.100s from %.200s port %d ssh2",
1.105 djm 292: authctxt->valid ? "" : "invalid user ",
293: authctxt->user,
1.114 djm 294: ssh_remote_ipaddr(ssh),
1.116 markus 295: ssh_remote_port(ssh));
1.138 djm 296: ssh_packet_disconnect(ssh, "Too many authentication failures");
1.105 djm 297: /* NOTREACHED */
1.13 markus 298: }
299:
300: /*
1.17 markus 301: * Check whether root logins are disallowed.
1.13 markus 302: */
303: int
1.126 djm 304: auth_root_allowed(struct ssh *ssh, const char *method)
1.13 markus 305: {
1.17 markus 306: switch (options.permit_root_login) {
307: case PERMIT_YES:
1.13 markus 308: return 1;
1.17 markus 309: case PERMIT_NO_PASSWD:
1.112 deraadt 310: if (strcmp(method, "publickey") == 0 ||
311: strcmp(method, "hostbased") == 0 ||
1.113 djm 312: strcmp(method, "gssapi-with-mic") == 0)
1.17 markus 313: return 1;
314: break;
315: case PERMIT_FORCED_ONLY:
1.126 djm 316: if (auth_opts->force_command != NULL) {
1.47 itojun 317: logit("Root login accepted for forced command.");
1.17 markus 318: return 1;
319: }
320: break;
1.13 markus 321: }
1.114 djm 322: logit("ROOT LOGIN REFUSED FROM %.200s port %d",
323: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1.22 markus 324: return 0;
325: }
326:
327:
328: /*
329: * Given a template and a passwd structure, build a filename
330: * by substituting % tokenised options. Currently, %% becomes '%',
331: * %h becomes the home directory and %u the username.
332: *
333: * This returns a buffer allocated by xmalloc.
334: */
1.93 djm 335: char *
1.59 djm 336: expand_authorized_keys(const char *filename, struct passwd *pw)
1.22 markus 337: {
1.129 djm 338: char *file, uidstr[32], ret[PATH_MAX];
1.65 djm 339: int i;
1.22 markus 340:
1.129 djm 341: snprintf(uidstr, sizeof(uidstr), "%llu",
342: (unsigned long long)pw->pw_uid);
1.59 djm 343: file = percent_expand(filename, "h", pw->pw_dir,
1.129 djm 344: "u", pw->pw_name, "U", uidstr, (char *)NULL);
1.22 markus 345:
346: /*
347: * Ensure that filename starts anchored. If not, be backward
348: * compatible and prepend the '%h/'
349: */
1.134 djm 350: if (path_absolute(file))
1.59 djm 351: return (file);
352:
1.65 djm 353: i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
354: if (i < 0 || (size_t)i >= sizeof(ret))
1.59 djm 355: fatal("expand_authorized_keys: path too long");
1.102 djm 356: free(file);
1.65 djm 357: return (xstrdup(ret));
1.22 markus 358: }
1.24 markus 359:
1.87 djm 360: char *
361: authorized_principals_file(struct passwd *pw)
362: {
1.111 djm 363: if (options.authorized_principals_file == NULL)
1.87 djm 364: return NULL;
365: return expand_authorized_keys(options.authorized_principals_file, pw);
366: }
367:
1.24 markus 368: /* return ok if key exists in sysfile or userfile */
369: HostStatus
1.121 markus 370: check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
1.24 markus 371: const char *sysfile, const char *userfile)
372: {
373: char *user_hostfile;
374: struct stat st;
1.30 stevesk 375: HostStatus host_status;
1.91 djm 376: struct hostkeys *hostkeys;
377: const struct hostkey_entry *found;
1.24 markus 378:
1.91 djm 379: hostkeys = init_hostkeys();
1.150 djm 380: load_hostkeys(hostkeys, host, sysfile, 0);
1.91 djm 381: if (userfile != NULL) {
1.24 markus 382: user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
383: if (options.strict_modes &&
384: (stat(user_hostfile, &st) == 0) &&
385: ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
1.31 deraadt 386: (st.st_mode & 022) != 0)) {
1.47 itojun 387: logit("Authentication refused for %.100s: "
1.24 markus 388: "bad owner or modes for %.200s",
389: pw->pw_name, user_hostfile);
1.88 djm 390: auth_debug_add("Ignored %.200s: bad ownership or modes",
391: user_hostfile);
1.24 markus 392: } else {
393: temporarily_use_uid(pw);
1.150 djm 394: load_hostkeys(hostkeys, host, user_hostfile, 0);
1.24 markus 395: restore_uid();
396: }
1.102 djm 397: free(user_hostfile);
1.24 markus 398: }
1.91 djm 399: host_status = check_key_in_hostkeys(hostkeys, key, &found);
400: if (host_status == HOST_REVOKED)
401: error("WARNING: revoked key for %s attempted authentication",
1.142 djm 402: host);
1.91 djm 403: else if (host_status == HOST_OK)
1.149 djm 404: debug_f("key for %s found at %s:%ld",
1.91 djm 405: found->host, found->file, found->line);
406: else
1.149 djm 407: debug_f("key for host %s not found", host);
1.91 djm 408:
409: free_hostkeys(hostkeys);
1.24 markus 410:
411: return host_status;
1.37 provos 412: }
413:
414: struct passwd *
1.138 djm 415: getpwnamallow(struct ssh *ssh, const char *user)
1.37 provos 416: {
1.38 provos 417: extern login_cap_t *lc;
418: auth_session_t *as;
1.37 provos 419: struct passwd *pw;
1.137 djm 420: struct connection_info *ci;
1.148 djm 421: u_int i;
1.71 dtucker 422:
1.137 djm 423: ci = get_connection_info(ssh, 1, options.use_dns);
1.96 dtucker 424: ci->user = user;
1.146 djm 425: parse_server_match_config(&options, &includes, ci);
1.120 djm 426: log_change_level(options.log_level);
1.148 djm 427: log_verbose_reset();
428: for (i = 0; i < options.num_log_verbose; i++)
429: log_verbose_add(options.log_verbose[i]);
1.124 djm 430: process_permitopen(ssh, &options);
1.37 provos 431:
432: pw = getpwnam(user);
1.45 stevesk 433: if (pw == NULL) {
1.114 djm 434: logit("Invalid user %.100s from %.100s port %d",
435: user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1.45 stevesk 436: return (NULL);
437: }
1.138 djm 438: if (!allowed_user(ssh, pw))
1.38 provos 439: return (NULL);
440: if ((lc = login_getclass(pw->pw_class)) == NULL) {
441: debug("unable to get login class: %s", user);
442: return (NULL);
443: }
444: if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
1.43 millert 445: auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
1.38 provos 446: debug("Approval failure for %s", user);
1.37 provos 447: pw = NULL;
1.38 provos 448: }
449: if (as != NULL)
450: auth_close(as);
1.41 markus 451: if (pw != NULL)
452: return (pwcopy(pw));
453: return (NULL);
1.85 djm 454: }
455:
456: /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
457: int
1.121 markus 458: auth_key_is_revoked(struct sshkey *key)
1.85 djm 459: {
1.107 djm 460: char *fp = NULL;
461: int r;
1.85 djm 462:
463: if (options.revoked_keys_file == NULL)
464: return 0;
1.108 djm 465: if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
466: SSH_FP_DEFAULT)) == NULL) {
1.107 djm 467: r = SSH_ERR_ALLOC_FAIL;
1.149 djm 468: error_fr(r, "fingerprint key");
1.107 djm 469: goto out;
470: }
471:
472: r = sshkey_check_revoked(key, options.revoked_keys_file);
473: switch (r) {
1.100 djm 474: case 0:
1.107 djm 475: break; /* not revoked */
476: case SSH_ERR_KEY_REVOKED:
477: error("Authentication key %s %s revoked by file %s",
478: sshkey_type(key), fp, options.revoked_keys_file);
479: goto out;
1.100 djm 480: default:
1.149 djm 481: error_r(r, "Error checking authentication key %s %s in "
482: "revoked keys file %s", sshkey_type(key), fp,
483: options.revoked_keys_file);
1.107 djm 484: goto out;
1.100 djm 485: }
1.107 djm 486:
487: /* Success */
488: r = 0;
489:
490: out:
491: free(fp);
492: return r == 0 ? 0 : 1;
1.42 markus 493: }
494:
495: void
496: auth_debug_add(const char *fmt,...)
497: {
498: char buf[1024];
499: va_list args;
1.131 markus 500: int r;
1.42 markus 501:
502: va_start(args, fmt);
503: vsnprintf(buf, sizeof(buf), fmt, args);
504: va_end(args);
1.159 dtucker 505: debug3("%s", buf);
506: if (auth_debug != NULL)
507: if ((r = sshbuf_put_cstring(auth_debug, buf)) != 0)
508: fatal_fr(r, "sshbuf_put_cstring");
1.42 markus 509: }
510:
511: void
1.138 djm 512: auth_debug_send(struct ssh *ssh)
1.42 markus 513: {
514: char *msg;
1.131 markus 515: int r;
1.42 markus 516:
1.131 markus 517: if (auth_debug == NULL)
1.42 markus 518: return;
1.131 markus 519: while (sshbuf_len(auth_debug) != 0) {
520: if ((r = sshbuf_get_cstring(auth_debug, &msg, NULL)) != 0)
1.149 djm 521: fatal_fr(r, "sshbuf_get_cstring");
1.131 markus 522: ssh_packet_send_debug(ssh, "%s", msg);
1.102 djm 523: free(msg);
1.42 markus 524: }
525: }
526:
527: void
528: auth_debug_reset(void)
529: {
1.131 markus 530: if (auth_debug != NULL)
531: sshbuf_reset(auth_debug);
532: else if ((auth_debug = sshbuf_new()) == NULL)
1.149 djm 533: fatal_f("sshbuf_new failed");
1.49 markus 534: }
535:
536: struct passwd *
537: fakepw(void)
538: {
1.154 djm 539: static int done = 0;
1.49 markus 540: static struct passwd fake;
1.154 djm 541: const char hashchars[] = "./ABCDEFGHIJKLMNOPQRSTUVWXYZ"
542: "abcdefghijklmnopqrstuvwxyz0123456789"; /* from bcrypt.c */
543: char *cp;
544:
545: if (done)
546: return (&fake);
1.49 markus 547:
548: memset(&fake, 0, sizeof(fake));
549: fake.pw_name = "NOUSER";
1.154 djm 550: fake.pw_passwd = xstrdup("$2a$10$"
551: "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
552: for (cp = fake.pw_passwd + 7; *cp != '\0'; cp++)
553: *cp = hashchars[arc4random_uniform(sizeof(hashchars) - 1)];
1.49 markus 554: fake.pw_gecos = "NOUSER";
1.53 deraadt 555: fake.pw_uid = (uid_t)-1;
556: fake.pw_gid = (gid_t)-1;
1.49 markus 557: fake.pw_class = "";
558: fake.pw_dir = "/nonexist";
559: fake.pw_shell = "/nonexist";
1.154 djm 560: done = 1;
1.49 markus 561:
562: return (&fake);
1.114 djm 563: }
564:
565: /*
566: * Returns the remote DNS hostname as a string. The returned string must not
567: * be freed. NB. this will usually trigger a DNS query the first time it is
568: * called.
569: * This function does additional checks on the hostname to mitigate some
1.153 dtucker 570: * attacks on based on conflation of hostnames and IP addresses.
1.114 djm 571: */
572:
573: static char *
574: remote_hostname(struct ssh *ssh)
575: {
576: struct sockaddr_storage from;
577: socklen_t fromlen;
578: struct addrinfo hints, *ai, *aitop;
579: char name[NI_MAXHOST], ntop2[NI_MAXHOST];
580: const char *ntop = ssh_remote_ipaddr(ssh);
581:
582: /* Get IP address of client. */
583: fromlen = sizeof(from);
584: memset(&from, 0, sizeof(from));
585: if (getpeername(ssh_packet_get_connection_in(ssh),
1.139 deraadt 586: (struct sockaddr *)&from, &fromlen) == -1) {
1.114 djm 587: debug("getpeername failed: %.100s", strerror(errno));
1.144 tobhe 588: return xstrdup(ntop);
1.114 djm 589: }
590:
591: debug3("Trying to reverse map address %.100s.", ntop);
592: /* Map the IP address to a host name. */
593: if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
594: NULL, 0, NI_NAMEREQD) != 0) {
595: /* Host name not found. Use ip address. */
1.144 tobhe 596: return xstrdup(ntop);
1.114 djm 597: }
598:
599: /*
600: * if reverse lookup result looks like a numeric hostname,
601: * someone is trying to trick us by PTR record like following:
602: * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
603: */
604: memset(&hints, 0, sizeof(hints));
605: hints.ai_socktype = SOCK_DGRAM; /*dummy*/
606: hints.ai_flags = AI_NUMERICHOST;
607: if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
608: logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
609: name, ntop);
610: freeaddrinfo(ai);
1.144 tobhe 611: return xstrdup(ntop);
1.114 djm 612: }
613:
614: /* Names are stored in lowercase. */
615: lowercase(name);
616:
617: /*
618: * Map it back to an IP address and check that the given
619: * address actually is an address of this host. This is
620: * necessary because anyone with access to a name server can
621: * define arbitrary names for an IP address. Mapping from
622: * name to IP address can be trusted better (but can still be
623: * fooled if the intruder has access to the name server of
624: * the domain).
625: */
626: memset(&hints, 0, sizeof(hints));
627: hints.ai_family = from.ss_family;
628: hints.ai_socktype = SOCK_STREAM;
629: if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
630: logit("reverse mapping checking getaddrinfo for %.700s "
1.115 dtucker 631: "[%s] failed.", name, ntop);
1.144 tobhe 632: return xstrdup(ntop);
1.114 djm 633: }
634: /* Look for the address from the list of addresses. */
635: for (ai = aitop; ai; ai = ai->ai_next) {
636: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
637: sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
638: (strcmp(ntop, ntop2) == 0))
639: break;
640: }
641: freeaddrinfo(aitop);
642: /* If we reached the end of the list, the address was not there. */
643: if (ai == NULL) {
644: /* Address not found for the host name. */
645: logit("Address %.100s maps to %.600s, but this does not "
1.115 dtucker 646: "map back to the address.", ntop, name);
1.144 tobhe 647: return xstrdup(ntop);
1.114 djm 648: }
1.144 tobhe 649: return xstrdup(name);
1.114 djm 650: }
651:
652: /*
653: * Return the canonical name of the host in the other side of the current
654: * connection. The host name is cached, so it is efficient to call this
655: * several times.
656: */
657:
658: const char *
659: auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
660: {
661: static char *dnsname;
662:
663: if (!use_dns)
664: return ssh_remote_ipaddr(ssh);
665: else if (dnsname != NULL)
666: return dnsname;
667: else {
668: dnsname = remote_hostname(ssh);
669: return dnsname;
670: }
1.126 djm 671: }
672:
673: /* These functions link key/cert options to the auth framework */
674:
675: /* Log sshauthopt options locally and (optionally) for remote transmission */
676: void
677: auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote)
678: {
679: int do_env = options.permit_user_env && opts->nenv > 0;
680: int do_permitopen = opts->npermitopen > 0 &&
681: (options.allow_tcp_forwarding & FORWARD_LOCAL) != 0;
1.130 djm 682: int do_permitlisten = opts->npermitlisten > 0 &&
683: (options.allow_tcp_forwarding & FORWARD_REMOTE) != 0;
1.126 djm 684: size_t i;
1.127 djm 685: char msg[1024], buf[64];
1.126 djm 686:
1.127 djm 687: snprintf(buf, sizeof(buf), "%d", opts->force_tun_device);
1.126 djm 688: /* Try to keep this alphabetically sorted */
1.147 djm 689: snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
1.126 djm 690: opts->permit_agent_forwarding_flag ? " agent-forwarding" : "",
691: opts->force_command == NULL ? "" : " command",
692: do_env ? " environment" : "",
1.127 djm 693: opts->valid_before == 0 ? "" : "expires",
1.147 djm 694: opts->no_require_user_presence ? " no-touch-required" : "",
1.126 djm 695: do_permitopen ? " permitopen" : "",
1.130 djm 696: do_permitlisten ? " permitlisten" : "",
1.126 djm 697: opts->permit_port_forwarding_flag ? " port-forwarding" : "",
698: opts->cert_principals == NULL ? "" : " principals",
699: opts->permit_pty_flag ? " pty" : "",
1.147 djm 700: opts->require_verify ? " uv" : "",
1.126 djm 701: opts->force_tun_device == -1 ? "" : " tun=",
1.127 djm 702: opts->force_tun_device == -1 ? "" : buf,
1.126 djm 703: opts->permit_user_rc ? " user-rc" : "",
1.147 djm 704: opts->permit_x11_forwarding_flag ? " x11-forwarding" : "");
1.126 djm 705:
706: debug("%s: %s", loc, msg);
707: if (do_remote)
708: auth_debug_add("%s: %s", loc, msg);
709:
710: if (options.permit_user_env) {
711: for (i = 0; i < opts->nenv; i++) {
712: debug("%s: environment: %s", loc, opts->env[i]);
713: if (do_remote) {
714: auth_debug_add("%s: environment: %s",
715: loc, opts->env[i]);
716: }
717: }
718: }
719:
720: /* Go into a little more details for the local logs. */
1.127 djm 721: if (opts->valid_before != 0) {
722: format_absolute_time(opts->valid_before, buf, sizeof(buf));
723: debug("%s: expires at %s", loc, buf);
724: }
1.126 djm 725: if (opts->cert_principals != NULL) {
726: debug("%s: authorized principals: \"%s\"",
727: loc, opts->cert_principals);
728: }
729: if (opts->force_command != NULL)
730: debug("%s: forced command: \"%s\"", loc, opts->force_command);
1.130 djm 731: if (do_permitopen) {
1.126 djm 732: for (i = 0; i < opts->npermitopen; i++) {
733: debug("%s: permitted open: %s",
734: loc, opts->permitopen[i]);
1.130 djm 735: }
736: }
737: if (do_permitlisten) {
738: for (i = 0; i < opts->npermitlisten; i++) {
739: debug("%s: permitted listen: %s",
740: loc, opts->permitlisten[i]);
1.126 djm 741: }
742: }
743: }
744:
745: /* Activate a new set of key/cert options; merging with what is there. */
746: int
747: auth_activate_options(struct ssh *ssh, struct sshauthopt *opts)
748: {
749: struct sshauthopt *old = auth_opts;
750: const char *emsg = NULL;
751:
1.149 djm 752: debug_f("setting new authentication options");
1.126 djm 753: if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) {
754: error("Inconsistent authentication options: %s", emsg);
755: return -1;
756: }
757: return 0;
758: }
759:
760: /* Disable forwarding, etc for the session */
761: void
762: auth_restrict_session(struct ssh *ssh)
763: {
764: struct sshauthopt *restricted;
765:
1.149 djm 766: debug_f("restricting session");
1.126 djm 767:
768: /* A blank sshauthopt defaults to permitting nothing */
1.155 dtucker 769: if ((restricted = sshauthopt_new()) == NULL)
770: fatal_f("sshauthopt_new failed");
1.128 djm 771: restricted->permit_pty_flag = 1;
1.126 djm 772: restricted->restricted = 1;
773:
774: if (auth_activate_options(ssh, restricted) != 0)
1.149 djm 775: fatal_f("failed to restrict session");
1.126 djm 776: sshauthopt_free(restricted);
1.1 markus 777: }
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