Annotation of src/usr.bin/ssh/auth.c, Revision 1.121
1.121 ! markus 1: /* $OpenBSD: auth.c,v 1.120 2017/05/17 01:24:17 djm 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>
1.22 markus 29:
1.70 stevesk 30: #include <errno.h>
1.79 dtucker 31: #include <fcntl.h>
1.22 markus 32: #include <libgen.h>
1.77 djm 33: #include <login_cap.h>
1.61 stevesk 34: #include <paths.h>
1.68 stevesk 35: #include <pwd.h>
1.69 stevesk 36: #include <stdarg.h>
1.74 stevesk 37: #include <stdio.h>
1.72 stevesk 38: #include <string.h>
1.80 djm 39: #include <unistd.h>
1.109 deraadt 40: #include <limits.h>
1.114 djm 41: #include <netdb.h>
1.1 markus 42:
43: #include "xmalloc.h"
1.13 markus 44: #include "match.h"
1.14 markus 45: #include "groupaccess.h"
46: #include "log.h"
1.75 deraadt 47: #include "buffer.h"
1.106 millert 48: #include "misc.h"
1.1 markus 49: #include "servconf.h"
1.75 deraadt 50: #include "key.h"
51: #include "hostfile.h"
1.2 markus 52: #include "auth.h"
1.13 markus 53: #include "auth-options.h"
1.14 markus 54: #include "canohost.h"
1.24 markus 55: #include "uidswap.h"
1.42 markus 56: #include "packet.h"
1.75 deraadt 57: #ifdef GSSAPI
58: #include "ssh-gss.h"
59: #endif
1.85 djm 60: #include "authfile.h"
1.67 dtucker 61: #include "monitor_wrap.h"
1.107 djm 62: #include "authfile.h"
63: #include "ssherr.h"
1.103 djm 64: #include "compat.h"
1.2 markus 65:
1.1 markus 66: /* import */
67: extern ServerOptions options;
1.67 dtucker 68: extern int use_privsep;
1.1 markus 69:
1.42 markus 70: /* Debugging messages */
71: Buffer auth_debug;
72: int auth_debug_init;
73:
1.1 markus 74: /*
1.12 markus 75: * Check if the user is allowed to log in via ssh. If user is listed
76: * in DenyUsers or one of user's groups is listed in DenyGroups, false
77: * will be returned. If AllowUsers isn't empty and user isn't listed
78: * there, or if AllowGroups isn't empty and one of user's groups isn't
79: * listed there, false will be returned.
1.1 markus 80: * If the user's shell is not executable, false will be returned.
1.4 markus 81: * Otherwise true is returned.
1.1 markus 82: */
1.5 markus 83: int
1.1 markus 84: allowed_user(struct passwd * pw)
85: {
1.114 djm 86: struct ssh *ssh = active_state; /* XXX */
1.1 markus 87: struct stat st;
1.35 markus 88: const char *hostname = NULL, *ipaddr = NULL;
1.117 djm 89: int r;
1.60 djm 90: u_int i;
1.1 markus 91:
92: /* Shouldn't be called if pw is NULL, but better safe than sorry... */
1.12 markus 93: if (!pw || !pw->pw_name)
1.1 markus 94: return 0;
95:
1.7 deraadt 96: /*
1.84 djm 97: * Deny if shell does not exist or is not executable unless we
98: * are chrooting.
1.7 deraadt 99: */
1.84 djm 100: if (options.chroot_directory == NULL ||
101: strcasecmp(options.chroot_directory, "none") == 0) {
102: char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
103: _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
104:
105: if (stat(shell, &st) != 0) {
106: logit("User %.100s not allowed because shell %.100s "
107: "does not exist", pw->pw_name, shell);
1.102 djm 108: free(shell);
1.84 djm 109: return 0;
110: }
111: if (S_ISREG(st.st_mode) == 0 ||
112: (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
113: logit("User %.100s not allowed because shell %.100s "
114: "is not executable", pw->pw_name, shell);
1.102 djm 115: free(shell);
1.84 djm 116: return 0;
117: }
1.102 djm 118: free(shell);
1.34 stevesk 119: }
1.1 markus 120:
1.58 dtucker 121: if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
122: options.num_deny_groups > 0 || options.num_allow_groups > 0) {
1.114 djm 123: hostname = auth_get_canonical_hostname(ssh, options.use_dns);
124: ipaddr = ssh_remote_ipaddr(ssh);
1.35 markus 125: }
126:
1.1 markus 127: /* Return false if user is listed in DenyUsers */
128: if (options.num_deny_users > 0) {
1.119 dtucker 129: for (i = 0; i < options.num_deny_users; i++) {
1.117 djm 130: r = match_user(pw->pw_name, hostname, ipaddr,
131: options.deny_users[i]);
132: if (r < 0) {
133: fatal("Invalid DenyUsers pattern \"%.100s\"",
134: options.deny_users[i]);
1.118 djm 135: } else if (r != 0) {
1.57 dtucker 136: logit("User %.100s from %.100s not allowed "
137: "because listed in DenyUsers",
138: pw->pw_name, hostname);
1.1 markus 139: return 0;
1.34 stevesk 140: }
1.119 dtucker 141: }
1.1 markus 142: }
143: /* Return false if AllowUsers isn't empty and user isn't listed there */
144: if (options.num_allow_users > 0) {
1.117 djm 145: for (i = 0; i < options.num_allow_users; i++) {
146: r = match_user(pw->pw_name, hostname, ipaddr,
147: options.allow_users[i]);
148: if (r < 0) {
149: fatal("Invalid AllowUsers pattern \"%.100s\"",
150: options.allow_users[i]);
151: } else if (r == 1)
1.1 markus 152: break;
1.117 djm 153: }
1.1 markus 154: /* i < options.num_allow_users iff we break for loop */
1.34 stevesk 155: if (i >= options.num_allow_users) {
1.57 dtucker 156: logit("User %.100s from %.100s not allowed because "
157: "not listed in AllowUsers", pw->pw_name, hostname);
1.1 markus 158: return 0;
1.34 stevesk 159: }
1.1 markus 160: }
161: if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
1.12 markus 162: /* Get the user's group access list (primary and supplementary) */
1.34 stevesk 163: if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
1.57 dtucker 164: logit("User %.100s from %.100s not allowed because "
165: "not in any group", pw->pw_name, hostname);
1.1 markus 166: return 0;
1.34 stevesk 167: }
1.1 markus 168:
1.12 markus 169: /* Return false if one of user's groups is listed in DenyGroups */
170: if (options.num_deny_groups > 0)
171: if (ga_match(options.deny_groups,
172: options.num_deny_groups)) {
173: ga_free();
1.57 dtucker 174: logit("User %.100s from %.100s not allowed "
175: "because a group is listed in DenyGroups",
176: pw->pw_name, hostname);
1.1 markus 177: return 0;
1.12 markus 178: }
1.1 markus 179: /*
1.12 markus 180: * Return false if AllowGroups isn't empty and one of user's groups
1.1 markus 181: * isn't listed there
182: */
1.12 markus 183: if (options.num_allow_groups > 0)
184: if (!ga_match(options.allow_groups,
185: options.num_allow_groups)) {
186: ga_free();
1.57 dtucker 187: logit("User %.100s from %.100s not allowed "
188: "because none of user's groups are listed "
189: "in AllowGroups", pw->pw_name, hostname);
1.1 markus 190: return 0;
1.12 markus 191: }
192: ga_free();
1.1 markus 193: }
194: /* We found no reason not to let this user try to log on... */
195: return 1;
1.13 markus 196: }
197:
198: void
1.103 djm 199: auth_info(Authctxt *authctxt, const char *fmt, ...)
200: {
201: va_list ap;
202: int i;
203:
204: free(authctxt->info);
205: authctxt->info = NULL;
206:
207: va_start(ap, fmt);
208: i = vasprintf(&authctxt->info, fmt, ap);
209: va_end(ap);
210:
211: if (i < 0 || authctxt->info == NULL)
212: fatal("vasprintf failed");
213: }
214:
215: void
1.98 djm 216: auth_log(Authctxt *authctxt, int authenticated, int partial,
1.103 djm 217: const char *method, const char *submethod)
1.13 markus 218: {
1.114 djm 219: struct ssh *ssh = active_state; /* XXX */
1.13 markus 220: void (*authlog) (const char *fmt,...) = verbose;
221: char *authmsg;
1.67 dtucker 222:
223: if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
224: return;
1.13 markus 225:
226: /* Raise logging level */
227: if (authenticated == 1 ||
228: !authctxt->valid ||
1.54 dtucker 229: authctxt->failures >= options.max_authtries / 2 ||
1.13 markus 230: strcmp(method, "password") == 0)
1.47 itojun 231: authlog = logit;
1.13 markus 232:
233: if (authctxt->postponed)
234: authmsg = "Postponed";
1.98 djm 235: else if (partial)
236: authmsg = "Partial";
1.13 markus 237: else
238: authmsg = authenticated ? "Accepted" : "Failed";
239:
1.116 markus 240: authlog("%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
1.13 markus 241: authmsg,
242: method,
1.98 djm 243: submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
1.56 markus 244: authctxt->valid ? "" : "invalid user ",
1.29 markus 245: authctxt->user,
1.114 djm 246: ssh_remote_ipaddr(ssh),
247: ssh_remote_port(ssh),
1.103 djm 248: authctxt->info != NULL ? ": " : "",
249: authctxt->info != NULL ? authctxt->info : "");
250: free(authctxt->info);
251: authctxt->info = NULL;
1.105 djm 252: }
253:
254: void
255: auth_maxtries_exceeded(Authctxt *authctxt)
256: {
1.114 djm 257: struct ssh *ssh = active_state; /* XXX */
258:
1.110 djm 259: error("maximum authentication attempts exceeded for "
1.116 markus 260: "%s%.100s from %.200s port %d ssh2",
1.105 djm 261: authctxt->valid ? "" : "invalid user ",
262: authctxt->user,
1.114 djm 263: ssh_remote_ipaddr(ssh),
1.116 markus 264: ssh_remote_port(ssh));
1.110 djm 265: packet_disconnect("Too many authentication failures");
1.105 djm 266: /* NOTREACHED */
1.13 markus 267: }
268:
269: /*
1.17 markus 270: * Check whether root logins are disallowed.
1.13 markus 271: */
272: int
1.98 djm 273: auth_root_allowed(const char *method)
1.13 markus 274: {
1.114 djm 275: struct ssh *ssh = active_state; /* XXX */
276:
1.17 markus 277: switch (options.permit_root_login) {
278: case PERMIT_YES:
1.13 markus 279: return 1;
1.17 markus 280: case PERMIT_NO_PASSWD:
1.112 deraadt 281: if (strcmp(method, "publickey") == 0 ||
282: strcmp(method, "hostbased") == 0 ||
1.113 djm 283: strcmp(method, "gssapi-with-mic") == 0)
1.17 markus 284: return 1;
285: break;
286: case PERMIT_FORCED_ONLY:
287: if (forced_command) {
1.47 itojun 288: logit("Root login accepted for forced command.");
1.17 markus 289: return 1;
290: }
291: break;
1.13 markus 292: }
1.114 djm 293: logit("ROOT LOGIN REFUSED FROM %.200s port %d",
294: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1.22 markus 295: return 0;
296: }
297:
298:
299: /*
300: * Given a template and a passwd structure, build a filename
301: * by substituting % tokenised options. Currently, %% becomes '%',
302: * %h becomes the home directory and %u the username.
303: *
304: * This returns a buffer allocated by xmalloc.
305: */
1.93 djm 306: char *
1.59 djm 307: expand_authorized_keys(const char *filename, struct passwd *pw)
1.22 markus 308: {
1.109 deraadt 309: char *file, ret[PATH_MAX];
1.65 djm 310: int i;
1.22 markus 311:
1.59 djm 312: file = percent_expand(filename, "h", pw->pw_dir,
313: "u", pw->pw_name, (char *)NULL);
1.22 markus 314:
315: /*
316: * Ensure that filename starts anchored. If not, be backward
317: * compatible and prepend the '%h/'
318: */
1.59 djm 319: if (*file == '/')
320: return (file);
321:
1.65 djm 322: i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
323: if (i < 0 || (size_t)i >= sizeof(ret))
1.59 djm 324: fatal("expand_authorized_keys: path too long");
1.102 djm 325: free(file);
1.65 djm 326: return (xstrdup(ret));
1.22 markus 327: }
1.24 markus 328:
1.87 djm 329: char *
330: authorized_principals_file(struct passwd *pw)
331: {
1.111 djm 332: if (options.authorized_principals_file == NULL)
1.87 djm 333: return NULL;
334: return expand_authorized_keys(options.authorized_principals_file, pw);
335: }
336:
1.24 markus 337: /* return ok if key exists in sysfile or userfile */
338: HostStatus
1.121 ! markus 339: check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
1.24 markus 340: const char *sysfile, const char *userfile)
341: {
342: char *user_hostfile;
343: struct stat st;
1.30 stevesk 344: HostStatus host_status;
1.91 djm 345: struct hostkeys *hostkeys;
346: const struct hostkey_entry *found;
1.24 markus 347:
1.91 djm 348: hostkeys = init_hostkeys();
349: load_hostkeys(hostkeys, host, sysfile);
350: if (userfile != NULL) {
1.24 markus 351: user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
352: if (options.strict_modes &&
353: (stat(user_hostfile, &st) == 0) &&
354: ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
1.31 deraadt 355: (st.st_mode & 022) != 0)) {
1.47 itojun 356: logit("Authentication refused for %.100s: "
1.24 markus 357: "bad owner or modes for %.200s",
358: pw->pw_name, user_hostfile);
1.88 djm 359: auth_debug_add("Ignored %.200s: bad ownership or modes",
360: user_hostfile);
1.24 markus 361: } else {
362: temporarily_use_uid(pw);
1.91 djm 363: load_hostkeys(hostkeys, host, user_hostfile);
1.24 markus 364: restore_uid();
365: }
1.102 djm 366: free(user_hostfile);
1.24 markus 367: }
1.91 djm 368: host_status = check_key_in_hostkeys(hostkeys, key, &found);
369: if (host_status == HOST_REVOKED)
370: error("WARNING: revoked key for %s attempted authentication",
371: found->host);
372: else if (host_status == HOST_OK)
373: debug("%s: key for %s found at %s:%ld", __func__,
374: found->host, found->file, found->line);
375: else
376: debug("%s: key for host %s not found", __func__, host);
377:
378: free_hostkeys(hostkeys);
1.24 markus 379:
380: return host_status;
381: }
382:
1.22 markus 383: /*
1.97 djm 384: * Check a given path for security. This is defined as all components
1.44 stevesk 385: * of the path to the file must be owned by either the owner of
1.23 markus 386: * of the file or root and no directories must be group or world writable.
1.22 markus 387: *
388: * XXX Should any specific check be done for sym links ?
389: *
1.101 dtucker 390: * Takes a file name, its stat information (preferably from fstat() to
1.97 djm 391: * avoid races), the uid of the expected owner, their home directory and an
1.22 markus 392: * error buffer plus max size as arguments.
393: *
394: * Returns 0 on success and -1 on failure
395: */
1.97 djm 396: int
397: auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
398: uid_t uid, char *err, size_t errlen)
1.22 markus 399: {
1.109 deraadt 400: char buf[PATH_MAX], homedir[PATH_MAX];
1.22 markus 401: char *cp;
1.46 markus 402: int comparehome = 0;
1.22 markus 403: struct stat st;
404:
1.97 djm 405: if (realpath(name, buf) == NULL) {
406: snprintf(err, errlen, "realpath %s failed: %s", name,
1.22 markus 407: strerror(errno));
408: return -1;
409: }
1.97 djm 410: if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
1.46 markus 411: comparehome = 1;
1.22 markus 412:
1.97 djm 413: if (!S_ISREG(stp->st_mode)) {
414: snprintf(err, errlen, "%s is not a regular file", buf);
415: return -1;
416: }
417: if ((stp->st_uid != 0 && stp->st_uid != uid) ||
418: (stp->st_mode & 022) != 0) {
1.22 markus 419: snprintf(err, errlen, "bad ownership or modes for file %s",
420: buf);
421: return -1;
422: }
423:
424: /* for each component of the canonical path, walking upwards */
425: for (;;) {
426: if ((cp = dirname(buf)) == NULL) {
427: snprintf(err, errlen, "dirname() failed");
428: return -1;
429: }
430: strlcpy(buf, cp, sizeof(buf));
1.25 provos 431:
1.22 markus 432: if (stat(buf, &st) < 0 ||
433: (st.st_uid != 0 && st.st_uid != uid) ||
434: (st.st_mode & 022) != 0) {
1.31 deraadt 435: snprintf(err, errlen,
1.22 markus 436: "bad ownership or modes for directory %s", buf);
437: return -1;
438: }
439:
1.82 dtucker 440: /* If are past the homedir then we can stop */
1.94 djm 441: if (comparehome && strcmp(homedir, buf) == 0)
1.27 markus 442: break;
1.94 djm 443:
1.22 markus 444: /*
445: * dirname should always complete with a "/" path,
446: * but we can be paranoid and check for "." too
447: */
448: if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
449: break;
450: }
1.17 markus 451: return 0;
1.97 djm 452: }
453:
454: /*
455: * Version of secure_path() that accepts an open file descriptor to
456: * avoid races.
457: *
458: * Returns 0 on success and -1 on failure
459: */
460: static int
461: secure_filename(FILE *f, const char *file, struct passwd *pw,
462: char *err, size_t errlen)
463: {
464: struct stat st;
465:
466: /* check the open file to avoid races */
467: if (fstat(fileno(f), &st) < 0) {
468: snprintf(err, errlen, "cannot stat file %s: %s",
1.99 dtucker 469: file, strerror(errno));
1.97 djm 470: return -1;
471: }
472: return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
1.79 dtucker 473: }
474:
1.87 djm 475: static FILE *
476: auth_openfile(const char *file, struct passwd *pw, int strict_modes,
477: int log_missing, char *file_type)
1.79 dtucker 478: {
479: char line[1024];
480: struct stat st;
481: int fd;
482: FILE *f;
483:
1.81 dtucker 484: if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
1.87 djm 485: if (log_missing || errno != ENOENT)
486: debug("Could not open %s '%s': %s", file_type, file,
1.81 dtucker 487: strerror(errno));
1.79 dtucker 488: return NULL;
1.81 dtucker 489: }
1.79 dtucker 490:
491: if (fstat(fd, &st) < 0) {
492: close(fd);
493: return NULL;
494: }
495: if (!S_ISREG(st.st_mode)) {
1.87 djm 496: logit("User %s %s %s is not a regular file",
497: pw->pw_name, file_type, file);
1.79 dtucker 498: close(fd);
499: return NULL;
500: }
501: unset_nonblock(fd);
502: if ((f = fdopen(fd, "r")) == NULL) {
503: close(fd);
504: return NULL;
505: }
1.90 djm 506: if (strict_modes &&
1.79 dtucker 507: secure_filename(f, file, pw, line, sizeof(line)) != 0) {
508: fclose(f);
509: logit("Authentication refused: %s", line);
1.88 djm 510: auth_debug_add("Ignored %s: %s", file_type, line);
1.79 dtucker 511: return NULL;
512: }
513:
514: return f;
1.87 djm 515: }
516:
517:
518: FILE *
519: auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
520: {
521: return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
522: }
523:
524: FILE *
525: auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
526: {
527: return auth_openfile(file, pw, strict_modes, 0,
528: "authorized principals");
1.37 provos 529: }
530:
531: struct passwd *
532: getpwnamallow(const char *user)
533: {
1.114 djm 534: struct ssh *ssh = active_state; /* XXX */
1.38 provos 535: extern login_cap_t *lc;
536: auth_session_t *as;
1.37 provos 537: struct passwd *pw;
1.96 dtucker 538: struct connection_info *ci = get_connection_info(1, options.use_dns);
1.71 dtucker 539:
1.96 dtucker 540: ci->user = user;
541: parse_server_match_config(&options, ci);
1.120 djm 542: log_change_level(options.log_level);
1.37 provos 543:
544: pw = getpwnam(user);
1.45 stevesk 545: if (pw == NULL) {
1.114 djm 546: logit("Invalid user %.100s from %.100s port %d",
547: user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1.45 stevesk 548: return (NULL);
549: }
550: if (!allowed_user(pw))
1.38 provos 551: return (NULL);
552: if ((lc = login_getclass(pw->pw_class)) == NULL) {
553: debug("unable to get login class: %s", user);
554: return (NULL);
555: }
556: if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
1.43 millert 557: auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
1.38 provos 558: debug("Approval failure for %s", user);
1.37 provos 559: pw = NULL;
1.38 provos 560: }
561: if (as != NULL)
562: auth_close(as);
1.41 markus 563: if (pw != NULL)
564: return (pwcopy(pw));
565: return (NULL);
1.85 djm 566: }
567:
568: /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
569: int
1.121 ! markus 570: auth_key_is_revoked(struct sshkey *key)
1.85 djm 571: {
1.107 djm 572: char *fp = NULL;
573: int r;
1.85 djm 574:
575: if (options.revoked_keys_file == NULL)
576: return 0;
1.108 djm 577: if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
578: SSH_FP_DEFAULT)) == NULL) {
1.107 djm 579: r = SSH_ERR_ALLOC_FAIL;
580: error("%s: fingerprint key: %s", __func__, ssh_err(r));
581: goto out;
582: }
583:
584: r = sshkey_check_revoked(key, options.revoked_keys_file);
585: switch (r) {
1.100 djm 586: case 0:
1.107 djm 587: break; /* not revoked */
588: case SSH_ERR_KEY_REVOKED:
589: error("Authentication key %s %s revoked by file %s",
590: sshkey_type(key), fp, options.revoked_keys_file);
591: goto out;
1.100 djm 592: default:
1.107 djm 593: error("Error checking authentication key %s %s in "
594: "revoked keys file %s: %s", sshkey_type(key), fp,
595: options.revoked_keys_file, ssh_err(r));
596: goto out;
1.100 djm 597: }
1.107 djm 598:
599: /* Success */
600: r = 0;
601:
602: out:
603: free(fp);
604: return r == 0 ? 0 : 1;
1.42 markus 605: }
606:
607: void
608: auth_debug_add(const char *fmt,...)
609: {
610: char buf[1024];
611: va_list args;
612:
613: if (!auth_debug_init)
614: return;
615:
616: va_start(args, fmt);
617: vsnprintf(buf, sizeof(buf), fmt, args);
618: va_end(args);
619: buffer_put_cstring(&auth_debug, buf);
620: }
621:
622: void
623: auth_debug_send(void)
624: {
625: char *msg;
626:
627: if (!auth_debug_init)
628: return;
629: while (buffer_len(&auth_debug)) {
630: msg = buffer_get_string(&auth_debug, NULL);
631: packet_send_debug("%s", msg);
1.102 djm 632: free(msg);
1.42 markus 633: }
634: }
635:
636: void
637: auth_debug_reset(void)
638: {
639: if (auth_debug_init)
640: buffer_clear(&auth_debug);
641: else {
642: buffer_init(&auth_debug);
643: auth_debug_init = 1;
644: }
1.49 markus 645: }
646:
647: struct passwd *
648: fakepw(void)
649: {
650: static struct passwd fake;
651:
652: memset(&fake, 0, sizeof(fake));
653: fake.pw_name = "NOUSER";
654: fake.pw_passwd =
1.51 djm 655: "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
1.49 markus 656: fake.pw_gecos = "NOUSER";
1.53 deraadt 657: fake.pw_uid = (uid_t)-1;
658: fake.pw_gid = (gid_t)-1;
1.49 markus 659: fake.pw_class = "";
660: fake.pw_dir = "/nonexist";
661: fake.pw_shell = "/nonexist";
662:
663: return (&fake);
1.114 djm 664: }
665:
666: /*
667: * Returns the remote DNS hostname as a string. The returned string must not
668: * be freed. NB. this will usually trigger a DNS query the first time it is
669: * called.
670: * This function does additional checks on the hostname to mitigate some
671: * attacks on legacy rhosts-style authentication.
672: * XXX is RhostsRSAAuthentication vulnerable to these?
673: * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
674: */
675:
676: static char *
677: remote_hostname(struct ssh *ssh)
678: {
679: struct sockaddr_storage from;
680: socklen_t fromlen;
681: struct addrinfo hints, *ai, *aitop;
682: char name[NI_MAXHOST], ntop2[NI_MAXHOST];
683: const char *ntop = ssh_remote_ipaddr(ssh);
684:
685: /* Get IP address of client. */
686: fromlen = sizeof(from);
687: memset(&from, 0, sizeof(from));
688: if (getpeername(ssh_packet_get_connection_in(ssh),
689: (struct sockaddr *)&from, &fromlen) < 0) {
690: debug("getpeername failed: %.100s", strerror(errno));
691: return strdup(ntop);
692: }
693:
694: debug3("Trying to reverse map address %.100s.", ntop);
695: /* Map the IP address to a host name. */
696: if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
697: NULL, 0, NI_NAMEREQD) != 0) {
698: /* Host name not found. Use ip address. */
699: return strdup(ntop);
700: }
701:
702: /*
703: * if reverse lookup result looks like a numeric hostname,
704: * someone is trying to trick us by PTR record like following:
705: * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
706: */
707: memset(&hints, 0, sizeof(hints));
708: hints.ai_socktype = SOCK_DGRAM; /*dummy*/
709: hints.ai_flags = AI_NUMERICHOST;
710: if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
711: logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
712: name, ntop);
713: freeaddrinfo(ai);
714: return strdup(ntop);
715: }
716:
717: /* Names are stored in lowercase. */
718: lowercase(name);
719:
720: /*
721: * Map it back to an IP address and check that the given
722: * address actually is an address of this host. This is
723: * necessary because anyone with access to a name server can
724: * define arbitrary names for an IP address. Mapping from
725: * name to IP address can be trusted better (but can still be
726: * fooled if the intruder has access to the name server of
727: * the domain).
728: */
729: memset(&hints, 0, sizeof(hints));
730: hints.ai_family = from.ss_family;
731: hints.ai_socktype = SOCK_STREAM;
732: if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
733: logit("reverse mapping checking getaddrinfo for %.700s "
1.115 dtucker 734: "[%s] failed.", name, ntop);
1.114 djm 735: return strdup(ntop);
736: }
737: /* Look for the address from the list of addresses. */
738: for (ai = aitop; ai; ai = ai->ai_next) {
739: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
740: sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
741: (strcmp(ntop, ntop2) == 0))
742: break;
743: }
744: freeaddrinfo(aitop);
745: /* If we reached the end of the list, the address was not there. */
746: if (ai == NULL) {
747: /* Address not found for the host name. */
748: logit("Address %.100s maps to %.600s, but this does not "
1.115 dtucker 749: "map back to the address.", ntop, name);
1.114 djm 750: return strdup(ntop);
751: }
752: return strdup(name);
753: }
754:
755: /*
756: * Return the canonical name of the host in the other side of the current
757: * connection. The host name is cached, so it is efficient to call this
758: * several times.
759: */
760:
761: const char *
762: auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
763: {
764: static char *dnsname;
765:
766: if (!use_dns)
767: return ssh_remote_ipaddr(ssh);
768: else if (dnsname != NULL)
769: return dnsname;
770: else {
771: dnsname = remote_hostname(ssh);
772: return dnsname;
773: }
1.1 markus 774: }
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