Annotation of src/usr.bin/ssh/auth.c, Revision 1.122
1.122 ! djm 1: /* $OpenBSD: auth.c,v 1.121 2017/05/30 08:52:19 markus 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:
1.122 ! djm 198: /*
! 199: * Formats any key left in authctxt->auth_method_key for inclusion in
! 200: * auth_log()'s message. Also includes authxtct->auth_method_info if present.
! 201: */
! 202: static char *
! 203: format_method_key(Authctxt *authctxt)
1.103 djm 204: {
1.122 ! djm 205: const struct sshkey *key = authctxt->auth_method_key;
! 206: const char *methinfo = authctxt->auth_method_info;
! 207: char *fp, *ret = NULL;
! 208:
! 209: if (key == NULL)
! 210: return NULL;
! 211:
! 212: if (key_is_cert(key)) {
! 213: fp = sshkey_fingerprint(key->cert->signature_key,
! 214: options.fingerprint_hash, SSH_FP_DEFAULT);
! 215: xasprintf(&ret, "%s ID %s (serial %llu) CA %s %s%s%s",
! 216: sshkey_type(key), key->cert->key_id,
! 217: (unsigned long long)key->cert->serial,
! 218: sshkey_type(key->cert->signature_key),
! 219: fp == NULL ? "(null)" : fp,
! 220: methinfo == NULL ? "" : ", ",
! 221: methinfo == NULL ? "" : methinfo);
! 222: free(fp);
! 223: } else {
! 224: fp = sshkey_fingerprint(key, options.fingerprint_hash,
! 225: SSH_FP_DEFAULT);
! 226: xasprintf(&ret, "%s %s%s%s", sshkey_type(key),
! 227: fp == NULL ? "(null)" : fp,
! 228: methinfo == NULL ? "" : ", ",
! 229: methinfo == NULL ? "" : methinfo);
! 230: free(fp);
! 231: }
! 232: return ret;
1.103 djm 233: }
234:
235: void
1.98 djm 236: auth_log(Authctxt *authctxt, int authenticated, int partial,
1.103 djm 237: const char *method, const char *submethod)
1.13 markus 238: {
1.114 djm 239: struct ssh *ssh = active_state; /* XXX */
1.13 markus 240: void (*authlog) (const char *fmt,...) = verbose;
1.122 ! djm 241: const char *authmsg;
! 242: char *extra = NULL;
1.67 dtucker 243:
244: if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
245: return;
1.13 markus 246:
247: /* Raise logging level */
248: if (authenticated == 1 ||
249: !authctxt->valid ||
1.54 dtucker 250: authctxt->failures >= options.max_authtries / 2 ||
1.13 markus 251: strcmp(method, "password") == 0)
1.47 itojun 252: authlog = logit;
1.13 markus 253:
254: if (authctxt->postponed)
255: authmsg = "Postponed";
1.98 djm 256: else if (partial)
257: authmsg = "Partial";
1.13 markus 258: else
259: authmsg = authenticated ? "Accepted" : "Failed";
260:
1.122 ! djm 261: if ((extra = format_method_key(authctxt)) == NULL) {
! 262: if (authctxt->auth_method_info != NULL)
! 263: extra = xstrdup(authctxt->auth_method_info);
! 264: }
! 265:
1.116 markus 266: authlog("%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
1.13 markus 267: authmsg,
268: method,
1.98 djm 269: submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
1.56 markus 270: authctxt->valid ? "" : "invalid user ",
1.29 markus 271: authctxt->user,
1.114 djm 272: ssh_remote_ipaddr(ssh),
273: ssh_remote_port(ssh),
1.122 ! djm 274: extra != NULL ? ": " : "",
! 275: extra != NULL ? extra : "");
! 276:
! 277: free(extra);
1.105 djm 278: }
279:
280: void
281: auth_maxtries_exceeded(Authctxt *authctxt)
282: {
1.114 djm 283: struct ssh *ssh = active_state; /* XXX */
284:
1.110 djm 285: error("maximum authentication attempts exceeded for "
1.116 markus 286: "%s%.100s from %.200s port %d ssh2",
1.105 djm 287: authctxt->valid ? "" : "invalid user ",
288: authctxt->user,
1.114 djm 289: ssh_remote_ipaddr(ssh),
1.116 markus 290: ssh_remote_port(ssh));
1.110 djm 291: packet_disconnect("Too many authentication failures");
1.105 djm 292: /* NOTREACHED */
1.13 markus 293: }
294:
295: /*
1.17 markus 296: * Check whether root logins are disallowed.
1.13 markus 297: */
298: int
1.98 djm 299: auth_root_allowed(const char *method)
1.13 markus 300: {
1.114 djm 301: struct ssh *ssh = active_state; /* XXX */
302:
1.17 markus 303: switch (options.permit_root_login) {
304: case PERMIT_YES:
1.13 markus 305: return 1;
1.17 markus 306: case PERMIT_NO_PASSWD:
1.112 deraadt 307: if (strcmp(method, "publickey") == 0 ||
308: strcmp(method, "hostbased") == 0 ||
1.113 djm 309: strcmp(method, "gssapi-with-mic") == 0)
1.17 markus 310: return 1;
311: break;
312: case PERMIT_FORCED_ONLY:
313: if (forced_command) {
1.47 itojun 314: logit("Root login accepted for forced command.");
1.17 markus 315: return 1;
316: }
317: break;
1.13 markus 318: }
1.114 djm 319: logit("ROOT LOGIN REFUSED FROM %.200s port %d",
320: ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1.22 markus 321: return 0;
322: }
323:
324:
325: /*
326: * Given a template and a passwd structure, build a filename
327: * by substituting % tokenised options. Currently, %% becomes '%',
328: * %h becomes the home directory and %u the username.
329: *
330: * This returns a buffer allocated by xmalloc.
331: */
1.93 djm 332: char *
1.59 djm 333: expand_authorized_keys(const char *filename, struct passwd *pw)
1.22 markus 334: {
1.109 deraadt 335: char *file, ret[PATH_MAX];
1.65 djm 336: int i;
1.22 markus 337:
1.59 djm 338: file = percent_expand(filename, "h", pw->pw_dir,
339: "u", pw->pw_name, (char *)NULL);
1.22 markus 340:
341: /*
342: * Ensure that filename starts anchored. If not, be backward
343: * compatible and prepend the '%h/'
344: */
1.59 djm 345: if (*file == '/')
346: return (file);
347:
1.65 djm 348: i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
349: if (i < 0 || (size_t)i >= sizeof(ret))
1.59 djm 350: fatal("expand_authorized_keys: path too long");
1.102 djm 351: free(file);
1.65 djm 352: return (xstrdup(ret));
1.22 markus 353: }
1.24 markus 354:
1.87 djm 355: char *
356: authorized_principals_file(struct passwd *pw)
357: {
1.111 djm 358: if (options.authorized_principals_file == NULL)
1.87 djm 359: return NULL;
360: return expand_authorized_keys(options.authorized_principals_file, pw);
361: }
362:
1.24 markus 363: /* return ok if key exists in sysfile or userfile */
364: HostStatus
1.121 markus 365: check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
1.24 markus 366: const char *sysfile, const char *userfile)
367: {
368: char *user_hostfile;
369: struct stat st;
1.30 stevesk 370: HostStatus host_status;
1.91 djm 371: struct hostkeys *hostkeys;
372: const struct hostkey_entry *found;
1.24 markus 373:
1.91 djm 374: hostkeys = init_hostkeys();
375: load_hostkeys(hostkeys, host, sysfile);
376: if (userfile != NULL) {
1.24 markus 377: user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
378: if (options.strict_modes &&
379: (stat(user_hostfile, &st) == 0) &&
380: ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
1.31 deraadt 381: (st.st_mode & 022) != 0)) {
1.47 itojun 382: logit("Authentication refused for %.100s: "
1.24 markus 383: "bad owner or modes for %.200s",
384: pw->pw_name, user_hostfile);
1.88 djm 385: auth_debug_add("Ignored %.200s: bad ownership or modes",
386: user_hostfile);
1.24 markus 387: } else {
388: temporarily_use_uid(pw);
1.91 djm 389: load_hostkeys(hostkeys, host, user_hostfile);
1.24 markus 390: restore_uid();
391: }
1.102 djm 392: free(user_hostfile);
1.24 markus 393: }
1.91 djm 394: host_status = check_key_in_hostkeys(hostkeys, key, &found);
395: if (host_status == HOST_REVOKED)
396: error("WARNING: revoked key for %s attempted authentication",
397: found->host);
398: else if (host_status == HOST_OK)
399: debug("%s: key for %s found at %s:%ld", __func__,
400: found->host, found->file, found->line);
401: else
402: debug("%s: key for host %s not found", __func__, host);
403:
404: free_hostkeys(hostkeys);
1.24 markus 405:
406: return host_status;
407: }
408:
1.22 markus 409: /*
1.97 djm 410: * Check a given path for security. This is defined as all components
1.44 stevesk 411: * of the path to the file must be owned by either the owner of
1.23 markus 412: * of the file or root and no directories must be group or world writable.
1.22 markus 413: *
414: * XXX Should any specific check be done for sym links ?
415: *
1.101 dtucker 416: * Takes a file name, its stat information (preferably from fstat() to
1.97 djm 417: * avoid races), the uid of the expected owner, their home directory and an
1.22 markus 418: * error buffer plus max size as arguments.
419: *
420: * Returns 0 on success and -1 on failure
421: */
1.97 djm 422: int
423: auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
424: uid_t uid, char *err, size_t errlen)
1.22 markus 425: {
1.109 deraadt 426: char buf[PATH_MAX], homedir[PATH_MAX];
1.22 markus 427: char *cp;
1.46 markus 428: int comparehome = 0;
1.22 markus 429: struct stat st;
430:
1.97 djm 431: if (realpath(name, buf) == NULL) {
432: snprintf(err, errlen, "realpath %s failed: %s", name,
1.22 markus 433: strerror(errno));
434: return -1;
435: }
1.97 djm 436: if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
1.46 markus 437: comparehome = 1;
1.22 markus 438:
1.97 djm 439: if (!S_ISREG(stp->st_mode)) {
440: snprintf(err, errlen, "%s is not a regular file", buf);
441: return -1;
442: }
443: if ((stp->st_uid != 0 && stp->st_uid != uid) ||
444: (stp->st_mode & 022) != 0) {
1.22 markus 445: snprintf(err, errlen, "bad ownership or modes for file %s",
446: buf);
447: return -1;
448: }
449:
450: /* for each component of the canonical path, walking upwards */
451: for (;;) {
452: if ((cp = dirname(buf)) == NULL) {
453: snprintf(err, errlen, "dirname() failed");
454: return -1;
455: }
456: strlcpy(buf, cp, sizeof(buf));
1.25 provos 457:
1.22 markus 458: if (stat(buf, &st) < 0 ||
459: (st.st_uid != 0 && st.st_uid != uid) ||
460: (st.st_mode & 022) != 0) {
1.31 deraadt 461: snprintf(err, errlen,
1.22 markus 462: "bad ownership or modes for directory %s", buf);
463: return -1;
464: }
465:
1.82 dtucker 466: /* If are past the homedir then we can stop */
1.94 djm 467: if (comparehome && strcmp(homedir, buf) == 0)
1.27 markus 468: break;
1.94 djm 469:
1.22 markus 470: /*
471: * dirname should always complete with a "/" path,
472: * but we can be paranoid and check for "." too
473: */
474: if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
475: break;
476: }
1.17 markus 477: return 0;
1.97 djm 478: }
479:
480: /*
481: * Version of secure_path() that accepts an open file descriptor to
482: * avoid races.
483: *
484: * Returns 0 on success and -1 on failure
485: */
486: static int
487: secure_filename(FILE *f, const char *file, struct passwd *pw,
488: char *err, size_t errlen)
489: {
490: struct stat st;
491:
492: /* check the open file to avoid races */
493: if (fstat(fileno(f), &st) < 0) {
494: snprintf(err, errlen, "cannot stat file %s: %s",
1.99 dtucker 495: file, strerror(errno));
1.97 djm 496: return -1;
497: }
498: return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
1.79 dtucker 499: }
500:
1.87 djm 501: static FILE *
502: auth_openfile(const char *file, struct passwd *pw, int strict_modes,
503: int log_missing, char *file_type)
1.79 dtucker 504: {
505: char line[1024];
506: struct stat st;
507: int fd;
508: FILE *f;
509:
1.81 dtucker 510: if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
1.87 djm 511: if (log_missing || errno != ENOENT)
512: debug("Could not open %s '%s': %s", file_type, file,
1.81 dtucker 513: strerror(errno));
1.79 dtucker 514: return NULL;
1.81 dtucker 515: }
1.79 dtucker 516:
517: if (fstat(fd, &st) < 0) {
518: close(fd);
519: return NULL;
520: }
521: if (!S_ISREG(st.st_mode)) {
1.87 djm 522: logit("User %s %s %s is not a regular file",
523: pw->pw_name, file_type, file);
1.79 dtucker 524: close(fd);
525: return NULL;
526: }
527: unset_nonblock(fd);
528: if ((f = fdopen(fd, "r")) == NULL) {
529: close(fd);
530: return NULL;
531: }
1.90 djm 532: if (strict_modes &&
1.79 dtucker 533: secure_filename(f, file, pw, line, sizeof(line)) != 0) {
534: fclose(f);
535: logit("Authentication refused: %s", line);
1.88 djm 536: auth_debug_add("Ignored %s: %s", file_type, line);
1.79 dtucker 537: return NULL;
538: }
539:
540: return f;
1.87 djm 541: }
542:
543:
544: FILE *
545: auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
546: {
547: return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
548: }
549:
550: FILE *
551: auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
552: {
553: return auth_openfile(file, pw, strict_modes, 0,
554: "authorized principals");
1.37 provos 555: }
556:
557: struct passwd *
558: getpwnamallow(const char *user)
559: {
1.114 djm 560: struct ssh *ssh = active_state; /* XXX */
1.38 provos 561: extern login_cap_t *lc;
562: auth_session_t *as;
1.37 provos 563: struct passwd *pw;
1.96 dtucker 564: struct connection_info *ci = get_connection_info(1, options.use_dns);
1.71 dtucker 565:
1.96 dtucker 566: ci->user = user;
567: parse_server_match_config(&options, ci);
1.120 djm 568: log_change_level(options.log_level);
1.37 provos 569:
570: pw = getpwnam(user);
1.45 stevesk 571: if (pw == NULL) {
1.114 djm 572: logit("Invalid user %.100s from %.100s port %d",
573: user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1.45 stevesk 574: return (NULL);
575: }
576: if (!allowed_user(pw))
1.38 provos 577: return (NULL);
578: if ((lc = login_getclass(pw->pw_class)) == NULL) {
579: debug("unable to get login class: %s", user);
580: return (NULL);
581: }
582: if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
1.43 millert 583: auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
1.38 provos 584: debug("Approval failure for %s", user);
1.37 provos 585: pw = NULL;
1.38 provos 586: }
587: if (as != NULL)
588: auth_close(as);
1.41 markus 589: if (pw != NULL)
590: return (pwcopy(pw));
591: return (NULL);
1.85 djm 592: }
593:
594: /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
595: int
1.121 markus 596: auth_key_is_revoked(struct sshkey *key)
1.85 djm 597: {
1.107 djm 598: char *fp = NULL;
599: int r;
1.85 djm 600:
601: if (options.revoked_keys_file == NULL)
602: return 0;
1.108 djm 603: if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
604: SSH_FP_DEFAULT)) == NULL) {
1.107 djm 605: r = SSH_ERR_ALLOC_FAIL;
606: error("%s: fingerprint key: %s", __func__, ssh_err(r));
607: goto out;
608: }
609:
610: r = sshkey_check_revoked(key, options.revoked_keys_file);
611: switch (r) {
1.100 djm 612: case 0:
1.107 djm 613: break; /* not revoked */
614: case SSH_ERR_KEY_REVOKED:
615: error("Authentication key %s %s revoked by file %s",
616: sshkey_type(key), fp, options.revoked_keys_file);
617: goto out;
1.100 djm 618: default:
1.107 djm 619: error("Error checking authentication key %s %s in "
620: "revoked keys file %s: %s", sshkey_type(key), fp,
621: options.revoked_keys_file, ssh_err(r));
622: goto out;
1.100 djm 623: }
1.107 djm 624:
625: /* Success */
626: r = 0;
627:
628: out:
629: free(fp);
630: return r == 0 ? 0 : 1;
1.42 markus 631: }
632:
633: void
634: auth_debug_add(const char *fmt,...)
635: {
636: char buf[1024];
637: va_list args;
638:
639: if (!auth_debug_init)
640: return;
641:
642: va_start(args, fmt);
643: vsnprintf(buf, sizeof(buf), fmt, args);
644: va_end(args);
645: buffer_put_cstring(&auth_debug, buf);
646: }
647:
648: void
649: auth_debug_send(void)
650: {
651: char *msg;
652:
653: if (!auth_debug_init)
654: return;
655: while (buffer_len(&auth_debug)) {
656: msg = buffer_get_string(&auth_debug, NULL);
657: packet_send_debug("%s", msg);
1.102 djm 658: free(msg);
1.42 markus 659: }
660: }
661:
662: void
663: auth_debug_reset(void)
664: {
665: if (auth_debug_init)
666: buffer_clear(&auth_debug);
667: else {
668: buffer_init(&auth_debug);
669: auth_debug_init = 1;
670: }
1.49 markus 671: }
672:
673: struct passwd *
674: fakepw(void)
675: {
676: static struct passwd fake;
677:
678: memset(&fake, 0, sizeof(fake));
679: fake.pw_name = "NOUSER";
680: fake.pw_passwd =
1.51 djm 681: "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
1.49 markus 682: fake.pw_gecos = "NOUSER";
1.53 deraadt 683: fake.pw_uid = (uid_t)-1;
684: fake.pw_gid = (gid_t)-1;
1.49 markus 685: fake.pw_class = "";
686: fake.pw_dir = "/nonexist";
687: fake.pw_shell = "/nonexist";
688:
689: return (&fake);
1.114 djm 690: }
691:
692: /*
693: * Returns the remote DNS hostname as a string. The returned string must not
694: * be freed. NB. this will usually trigger a DNS query the first time it is
695: * called.
696: * This function does additional checks on the hostname to mitigate some
697: * attacks on legacy rhosts-style authentication.
698: * XXX is RhostsRSAAuthentication vulnerable to these?
699: * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
700: */
701:
702: static char *
703: remote_hostname(struct ssh *ssh)
704: {
705: struct sockaddr_storage from;
706: socklen_t fromlen;
707: struct addrinfo hints, *ai, *aitop;
708: char name[NI_MAXHOST], ntop2[NI_MAXHOST];
709: const char *ntop = ssh_remote_ipaddr(ssh);
710:
711: /* Get IP address of client. */
712: fromlen = sizeof(from);
713: memset(&from, 0, sizeof(from));
714: if (getpeername(ssh_packet_get_connection_in(ssh),
715: (struct sockaddr *)&from, &fromlen) < 0) {
716: debug("getpeername failed: %.100s", strerror(errno));
717: return strdup(ntop);
718: }
719:
720: debug3("Trying to reverse map address %.100s.", ntop);
721: /* Map the IP address to a host name. */
722: if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
723: NULL, 0, NI_NAMEREQD) != 0) {
724: /* Host name not found. Use ip address. */
725: return strdup(ntop);
726: }
727:
728: /*
729: * if reverse lookup result looks like a numeric hostname,
730: * someone is trying to trick us by PTR record like following:
731: * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
732: */
733: memset(&hints, 0, sizeof(hints));
734: hints.ai_socktype = SOCK_DGRAM; /*dummy*/
735: hints.ai_flags = AI_NUMERICHOST;
736: if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
737: logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
738: name, ntop);
739: freeaddrinfo(ai);
740: return strdup(ntop);
741: }
742:
743: /* Names are stored in lowercase. */
744: lowercase(name);
745:
746: /*
747: * Map it back to an IP address and check that the given
748: * address actually is an address of this host. This is
749: * necessary because anyone with access to a name server can
750: * define arbitrary names for an IP address. Mapping from
751: * name to IP address can be trusted better (but can still be
752: * fooled if the intruder has access to the name server of
753: * the domain).
754: */
755: memset(&hints, 0, sizeof(hints));
756: hints.ai_family = from.ss_family;
757: hints.ai_socktype = SOCK_STREAM;
758: if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
759: logit("reverse mapping checking getaddrinfo for %.700s "
1.115 dtucker 760: "[%s] failed.", name, ntop);
1.114 djm 761: return strdup(ntop);
762: }
763: /* Look for the address from the list of addresses. */
764: for (ai = aitop; ai; ai = ai->ai_next) {
765: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
766: sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
767: (strcmp(ntop, ntop2) == 0))
768: break;
769: }
770: freeaddrinfo(aitop);
771: /* If we reached the end of the list, the address was not there. */
772: if (ai == NULL) {
773: /* Address not found for the host name. */
774: logit("Address %.100s maps to %.600s, but this does not "
1.115 dtucker 775: "map back to the address.", ntop, name);
1.114 djm 776: return strdup(ntop);
777: }
778: return strdup(name);
779: }
780:
781: /*
782: * Return the canonical name of the host in the other side of the current
783: * connection. The host name is cached, so it is efficient to call this
784: * several times.
785: */
786:
787: const char *
788: auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
789: {
790: static char *dnsname;
791:
792: if (!use_dns)
793: return ssh_remote_ipaddr(ssh);
794: else if (dnsname != NULL)
795: return dnsname;
796: else {
797: dnsname = remote_hostname(ssh);
798: return dnsname;
799: }
1.1 markus 800: }