Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 1 | /* $OpenBSD: auth.c,v 1.119 2016/12/15 21:29:05 dtucker Exp $ */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 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> |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 30 | #include <sys/socket.h> |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 31 | |
| 32 | #include <netinet/in.h> |
| 33 | |
| 34 | #include <errno.h> |
| 35 | #include <fcntl.h> |
| 36 | #ifdef HAVE_PATHS_H |
| 37 | # include <paths.h> |
| 38 | #endif |
| 39 | #include <pwd.h> |
| 40 | #ifdef HAVE_LOGIN_H |
| 41 | #include <login.h> |
| 42 | #endif |
| 43 | #ifdef USE_SHADOW |
| 44 | #include <shadow.h> |
| 45 | #endif |
| 46 | #ifdef HAVE_LIBGEN_H |
| 47 | #include <libgen.h> |
| 48 | #endif |
| 49 | #include <stdarg.h> |
| 50 | #include <stdio.h> |
| 51 | #include <string.h> |
| 52 | #include <unistd.h> |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 53 | #include <limits.h> |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 54 | #include <netdb.h> |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 55 | |
| 56 | #include "xmalloc.h" |
| 57 | #include "match.h" |
| 58 | #include "groupaccess.h" |
| 59 | #include "log.h" |
| 60 | #include "buffer.h" |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 61 | #include "misc.h" |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 62 | #include "servconf.h" |
| 63 | #include "key.h" |
| 64 | #include "hostfile.h" |
| 65 | #include "auth.h" |
| 66 | #include "auth-options.h" |
| 67 | #include "canohost.h" |
| 68 | #include "uidswap.h" |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 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" |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 76 | #include "authfile.h" |
| 77 | #include "ssherr.h" |
| 78 | #include "compat.h" |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 79 | |
| 80 | /* import */ |
| 81 | extern ServerOptions options; |
| 82 | extern int use_privsep; |
| 83 | extern Buffer loginmsg; |
| 84 | extern struct passwd *privsep_pw; |
| 85 | |
| 86 | /* Debugging messages */ |
| 87 | Buffer auth_debug; |
| 88 | int auth_debug_init; |
| 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 |
| 100 | allowed_user(struct passwd * pw) |
| 101 | { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 102 | struct ssh *ssh = active_state; /* XXX */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 103 | struct stat st; |
| 104 | const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL; |
| 105 | u_int i; |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 106 | int r; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 107 | #ifdef USE_SHADOW |
| 108 | struct spwd *spw = NULL; |
| 109 | #endif |
| 110 | |
| 111 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ |
| 112 | if (!pw || !pw->pw_name) |
| 113 | return 0; |
| 114 | |
| 115 | #ifdef USE_SHADOW |
| 116 | if (!options.use_pam) |
| 117 | spw = getspnam(pw->pw_name); |
| 118 | #ifdef HAS_SHADOW_EXPIRE |
| 119 | if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw)) |
| 120 | return 0; |
| 121 | #endif /* HAS_SHADOW_EXPIRE */ |
| 122 | #endif /* USE_SHADOW */ |
| 123 | |
| 124 | /* grab passwd field for locked account check */ |
| 125 | passwd = pw->pw_passwd; |
| 126 | #ifdef USE_SHADOW |
| 127 | if (spw != NULL) |
| 128 | #ifdef USE_LIBIAF |
| 129 | passwd = get_iaf_password(pw); |
| 130 | #else |
| 131 | passwd = spw->sp_pwdp; |
| 132 | #endif /* USE_LIBIAF */ |
| 133 | #endif |
| 134 | |
| 135 | /* check for locked account */ |
| 136 | if (!options.use_pam && passwd && *passwd) { |
| 137 | int locked = 0; |
| 138 | |
| 139 | #ifdef LOCKED_PASSWD_STRING |
| 140 | if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0) |
| 141 | locked = 1; |
| 142 | #endif |
| 143 | #ifdef LOCKED_PASSWD_PREFIX |
| 144 | if (strncmp(passwd, LOCKED_PASSWD_PREFIX, |
| 145 | strlen(LOCKED_PASSWD_PREFIX)) == 0) |
| 146 | locked = 1; |
| 147 | #endif |
| 148 | #ifdef LOCKED_PASSWD_SUBSTR |
| 149 | if (strstr(passwd, LOCKED_PASSWD_SUBSTR)) |
| 150 | locked = 1; |
| 151 | #endif |
| 152 | #ifdef USE_LIBIAF |
| 153 | free((void *) passwd); |
| 154 | #endif /* USE_LIBIAF */ |
| 155 | if (locked) { |
| 156 | logit("User %.100s not allowed because account is locked", |
| 157 | pw->pw_name); |
| 158 | return 0; |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | /* |
| 163 | * Deny if shell does not exist or is not executable unless we |
| 164 | * are chrooting. |
| 165 | */ |
| 166 | if (options.chroot_directory == NULL || |
| 167 | strcasecmp(options.chroot_directory, "none") == 0) { |
| 168 | char *shell = xstrdup((pw->pw_shell[0] == '\0') ? |
| 169 | _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */ |
| 170 | |
| 171 | if (stat(shell, &st) != 0) { |
| 172 | logit("User %.100s not allowed because shell %.100s " |
| 173 | "does not exist", pw->pw_name, shell); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 174 | free(shell); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 175 | return 0; |
| 176 | } |
| 177 | if (S_ISREG(st.st_mode) == 0 || |
| 178 | (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { |
| 179 | logit("User %.100s not allowed because shell %.100s " |
| 180 | "is not executable", pw->pw_name, shell); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 181 | free(shell); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 182 | return 0; |
| 183 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 184 | free(shell); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 185 | } |
| 186 | |
| 187 | if (options.num_deny_users > 0 || options.num_allow_users > 0 || |
| 188 | options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 189 | hostname = auth_get_canonical_hostname(ssh, options.use_dns); |
| 190 | ipaddr = ssh_remote_ipaddr(ssh); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 191 | } |
| 192 | |
| 193 | /* Return false if user is listed in DenyUsers */ |
| 194 | if (options.num_deny_users > 0) { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 195 | for (i = 0; i < options.num_deny_users; i++) { |
| 196 | r = match_user(pw->pw_name, hostname, ipaddr, |
| 197 | options.deny_users[i]); |
| 198 | if (r < 0) { |
| 199 | fatal("Invalid DenyUsers pattern \"%.100s\"", |
| 200 | options.deny_users[i]); |
| 201 | } else if (r != 0) { |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 202 | logit("User %.100s from %.100s not allowed " |
| 203 | "because listed in DenyUsers", |
| 204 | pw->pw_name, hostname); |
| 205 | return 0; |
| 206 | } |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 207 | } |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 208 | } |
| 209 | /* Return false if AllowUsers isn't empty and user isn't listed there */ |
| 210 | if (options.num_allow_users > 0) { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 211 | for (i = 0; i < options.num_allow_users; i++) { |
| 212 | r = match_user(pw->pw_name, hostname, ipaddr, |
| 213 | options.allow_users[i]); |
| 214 | if (r < 0) { |
| 215 | fatal("Invalid AllowUsers pattern \"%.100s\"", |
| 216 | options.allow_users[i]); |
| 217 | } else if (r == 1) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 218 | break; |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 219 | } |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 220 | /* i < options.num_allow_users iff we break for loop */ |
| 221 | if (i >= options.num_allow_users) { |
| 222 | logit("User %.100s from %.100s not allowed because " |
| 223 | "not listed in AllowUsers", pw->pw_name, hostname); |
| 224 | return 0; |
| 225 | } |
| 226 | } |
| 227 | if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
| 228 | /* Get the user's group access list (primary and supplementary) */ |
| 229 | if (ga_init(pw->pw_name, pw->pw_gid) == 0) { |
| 230 | logit("User %.100s from %.100s not allowed because " |
| 231 | "not in any group", pw->pw_name, hostname); |
| 232 | return 0; |
| 233 | } |
| 234 | |
| 235 | /* Return false if one of user's groups is listed in DenyGroups */ |
| 236 | if (options.num_deny_groups > 0) |
| 237 | if (ga_match(options.deny_groups, |
| 238 | options.num_deny_groups)) { |
| 239 | ga_free(); |
| 240 | logit("User %.100s from %.100s not allowed " |
| 241 | "because a group is listed in DenyGroups", |
| 242 | pw->pw_name, hostname); |
| 243 | return 0; |
| 244 | } |
| 245 | /* |
| 246 | * Return false if AllowGroups isn't empty and one of user's groups |
| 247 | * isn't listed there |
| 248 | */ |
| 249 | if (options.num_allow_groups > 0) |
| 250 | if (!ga_match(options.allow_groups, |
| 251 | options.num_allow_groups)) { |
| 252 | ga_free(); |
| 253 | logit("User %.100s from %.100s not allowed " |
| 254 | "because none of user's groups are listed " |
| 255 | "in AllowGroups", pw->pw_name, hostname); |
| 256 | return 0; |
| 257 | } |
| 258 | ga_free(); |
| 259 | } |
| 260 | |
| 261 | #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER |
| 262 | if (!sys_auth_allowed_user(pw, &loginmsg)) |
| 263 | return 0; |
| 264 | #endif |
| 265 | |
| 266 | /* We found no reason not to let this user try to log on... */ |
| 267 | return 1; |
| 268 | } |
| 269 | |
| 270 | void |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 271 | auth_info(Authctxt *authctxt, const char *fmt, ...) |
| 272 | { |
| 273 | va_list ap; |
| 274 | int i; |
| 275 | |
| 276 | free(authctxt->info); |
| 277 | authctxt->info = NULL; |
| 278 | |
| 279 | va_start(ap, fmt); |
| 280 | i = vasprintf(&authctxt->info, fmt, ap); |
| 281 | va_end(ap); |
| 282 | |
| 283 | if (i < 0 || authctxt->info == NULL) |
| 284 | fatal("vasprintf failed"); |
| 285 | } |
| 286 | |
| 287 | void |
| 288 | auth_log(Authctxt *authctxt, int authenticated, int partial, |
| 289 | const char *method, const char *submethod) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 290 | { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 291 | struct ssh *ssh = active_state; /* XXX */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 292 | void (*authlog) (const char *fmt,...) = verbose; |
| 293 | char *authmsg; |
| 294 | |
| 295 | if (use_privsep && !mm_is_monitor() && !authctxt->postponed) |
| 296 | return; |
| 297 | |
| 298 | /* Raise logging level */ |
| 299 | if (authenticated == 1 || |
| 300 | !authctxt->valid || |
| 301 | authctxt->failures >= options.max_authtries / 2 || |
| 302 | strcmp(method, "password") == 0) |
| 303 | authlog = logit; |
| 304 | |
| 305 | if (authctxt->postponed) |
| 306 | authmsg = "Postponed"; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 307 | else if (partial) |
| 308 | authmsg = "Partial"; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 309 | else |
| 310 | authmsg = authenticated ? "Accepted" : "Failed"; |
| 311 | |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 312 | authlog("%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s", |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 313 | authmsg, |
| 314 | method, |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 315 | submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod, |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 316 | authctxt->valid ? "" : "invalid user ", |
| 317 | authctxt->user, |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 318 | ssh_remote_ipaddr(ssh), |
| 319 | ssh_remote_port(ssh), |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 320 | authctxt->info != NULL ? ": " : "", |
| 321 | authctxt->info != NULL ? authctxt->info : ""); |
| 322 | free(authctxt->info); |
| 323 | authctxt->info = NULL; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 324 | |
| 325 | #ifdef CUSTOM_FAILED_LOGIN |
| 326 | if (authenticated == 0 && !authctxt->postponed && |
| 327 | (strcmp(method, "password") == 0 || |
| 328 | strncmp(method, "keyboard-interactive", 20) == 0 || |
| 329 | strcmp(method, "challenge-response") == 0)) |
| 330 | record_failed_login(authctxt->user, |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 331 | auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 332 | # ifdef WITH_AIXAUTHENTICATE |
| 333 | if (authenticated) |
| 334 | sys_auth_record_login(authctxt->user, |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 335 | auth_get_canonical_hostname(ssh, options.use_dns), "ssh", |
| 336 | &loginmsg); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 337 | # endif |
| 338 | #endif |
| 339 | #ifdef SSH_AUDIT_EVENTS |
| 340 | if (authenticated == 0 && !authctxt->postponed) |
| 341 | audit_event(audit_classify_auth(method)); |
| 342 | #endif |
| 343 | } |
| 344 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 345 | |
| 346 | void |
| 347 | auth_maxtries_exceeded(Authctxt *authctxt) |
| 348 | { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 349 | struct ssh *ssh = active_state; /* XXX */ |
| 350 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 351 | error("maximum authentication attempts exceeded for " |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 352 | "%s%.100s from %.200s port %d ssh2", |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 353 | authctxt->valid ? "" : "invalid user ", |
| 354 | authctxt->user, |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 355 | ssh_remote_ipaddr(ssh), |
| 356 | ssh_remote_port(ssh)); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 357 | packet_disconnect("Too many authentication failures"); |
| 358 | /* NOTREACHED */ |
| 359 | } |
| 360 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 361 | /* |
| 362 | * Check whether root logins are disallowed. |
| 363 | */ |
| 364 | int |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 365 | auth_root_allowed(const char *method) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 366 | { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 367 | struct ssh *ssh = active_state; /* XXX */ |
| 368 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 369 | switch (options.permit_root_login) { |
| 370 | case PERMIT_YES: |
| 371 | return 1; |
| 372 | case PERMIT_NO_PASSWD: |
Greg Hartman | ccacbc9 | 2016-02-03 09:59:44 -0800 | [diff] [blame] | 373 | if (strcmp(method, "publickey") == 0 || |
| 374 | strcmp(method, "hostbased") == 0 || |
| 375 | strcmp(method, "gssapi-with-mic") == 0) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 376 | return 1; |
| 377 | break; |
| 378 | case PERMIT_FORCED_ONLY: |
| 379 | if (forced_command) { |
| 380 | logit("Root login accepted for forced command."); |
| 381 | return 1; |
| 382 | } |
| 383 | break; |
| 384 | } |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 385 | logit("ROOT LOGIN REFUSED FROM %.200s port %d", |
| 386 | ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 387 | return 0; |
| 388 | } |
| 389 | |
| 390 | |
| 391 | /* |
| 392 | * Given a template and a passwd structure, build a filename |
| 393 | * by substituting % tokenised options. Currently, %% becomes '%', |
| 394 | * %h becomes the home directory and %u the username. |
| 395 | * |
| 396 | * This returns a buffer allocated by xmalloc. |
| 397 | */ |
| 398 | char * |
| 399 | expand_authorized_keys(const char *filename, struct passwd *pw) |
| 400 | { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 401 | char *file, ret[PATH_MAX]; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 402 | int i; |
| 403 | |
| 404 | file = percent_expand(filename, "h", pw->pw_dir, |
| 405 | "u", pw->pw_name, (char *)NULL); |
| 406 | |
| 407 | /* |
| 408 | * Ensure that filename starts anchored. If not, be backward |
| 409 | * compatible and prepend the '%h/' |
| 410 | */ |
| 411 | if (*file == '/') |
| 412 | return (file); |
| 413 | |
| 414 | i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file); |
| 415 | if (i < 0 || (size_t)i >= sizeof(ret)) |
| 416 | fatal("expand_authorized_keys: path too long"); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 417 | free(file); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 418 | return (xstrdup(ret)); |
| 419 | } |
| 420 | |
| 421 | char * |
| 422 | authorized_principals_file(struct passwd *pw) |
| 423 | { |
Greg Hartman | ccacbc9 | 2016-02-03 09:59:44 -0800 | [diff] [blame] | 424 | if (options.authorized_principals_file == NULL) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 425 | return NULL; |
| 426 | return expand_authorized_keys(options.authorized_principals_file, pw); |
| 427 | } |
| 428 | |
| 429 | /* return ok if key exists in sysfile or userfile */ |
| 430 | HostStatus |
| 431 | check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host, |
| 432 | const char *sysfile, const char *userfile) |
| 433 | { |
| 434 | char *user_hostfile; |
| 435 | struct stat st; |
| 436 | HostStatus host_status; |
| 437 | struct hostkeys *hostkeys; |
| 438 | const struct hostkey_entry *found; |
| 439 | |
| 440 | hostkeys = init_hostkeys(); |
| 441 | load_hostkeys(hostkeys, host, sysfile); |
| 442 | if (userfile != NULL) { |
| 443 | user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); |
| 444 | if (options.strict_modes && |
| 445 | (stat(user_hostfile, &st) == 0) && |
| 446 | ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || |
| 447 | (st.st_mode & 022) != 0)) { |
| 448 | logit("Authentication refused for %.100s: " |
| 449 | "bad owner or modes for %.200s", |
| 450 | pw->pw_name, user_hostfile); |
| 451 | auth_debug_add("Ignored %.200s: bad ownership or modes", |
| 452 | user_hostfile); |
| 453 | } else { |
| 454 | temporarily_use_uid(pw); |
| 455 | load_hostkeys(hostkeys, host, user_hostfile); |
| 456 | restore_uid(); |
| 457 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 458 | free(user_hostfile); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 459 | } |
| 460 | host_status = check_key_in_hostkeys(hostkeys, key, &found); |
| 461 | if (host_status == HOST_REVOKED) |
| 462 | error("WARNING: revoked key for %s attempted authentication", |
| 463 | found->host); |
| 464 | else if (host_status == HOST_OK) |
| 465 | debug("%s: key for %s found at %s:%ld", __func__, |
| 466 | found->host, found->file, found->line); |
| 467 | else |
| 468 | debug("%s: key for host %s not found", __func__, host); |
| 469 | |
| 470 | free_hostkeys(hostkeys); |
| 471 | |
| 472 | return host_status; |
| 473 | } |
| 474 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 475 | /* |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 476 | * Check a given path for security. This is defined as all components |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 477 | * of the path to the file must be owned by either the owner of |
| 478 | * of the file or root and no directories must be group or world writable. |
| 479 | * |
| 480 | * XXX Should any specific check be done for sym links ? |
| 481 | * |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 482 | * Takes a file name, its stat information (preferably from fstat() to |
| 483 | * avoid races), the uid of the expected owner, their home directory and an |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 484 | * error buffer plus max size as arguments. |
| 485 | * |
| 486 | * Returns 0 on success and -1 on failure |
| 487 | */ |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 488 | int |
| 489 | auth_secure_path(const char *name, struct stat *stp, const char *pw_dir, |
| 490 | uid_t uid, char *err, size_t errlen) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 491 | { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 492 | char buf[PATH_MAX], homedir[PATH_MAX]; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 493 | char *cp; |
| 494 | int comparehome = 0; |
| 495 | struct stat st; |
| 496 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 497 | if (realpath(name, buf) == NULL) { |
| 498 | snprintf(err, errlen, "realpath %s failed: %s", name, |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 499 | strerror(errno)); |
| 500 | return -1; |
| 501 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 502 | if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 503 | comparehome = 1; |
| 504 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 505 | if (!S_ISREG(stp->st_mode)) { |
| 506 | snprintf(err, errlen, "%s is not a regular file", buf); |
| 507 | return -1; |
| 508 | } |
| 509 | if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) || |
| 510 | (stp->st_mode & 022) != 0) { |
| 511 | #if defined(ANDROID) |
| 512 | /* needed to allow root login on Android. */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 513 | if (getuid() != 0) |
| 514 | #endif |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 515 | { |
| 516 | snprintf(err, errlen, "bad ownership or modes for file %s", |
| 517 | buf); |
| 518 | return -1; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 519 | } |
| 520 | } |
| 521 | |
| 522 | /* for each component of the canonical path, walking upwards */ |
| 523 | for (;;) { |
| 524 | if ((cp = dirname(buf)) == NULL) { |
| 525 | snprintf(err, errlen, "dirname() failed"); |
| 526 | return -1; |
| 527 | } |
| 528 | strlcpy(buf, cp, sizeof(buf)); |
| 529 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 530 | #if !defined(ANDROID) |
| 531 | /* /data is owned by system user, which causes this check to fail */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 532 | if (stat(buf, &st) < 0 || |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 533 | (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) || |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 534 | (st.st_mode & 022) != 0) { |
| 535 | snprintf(err, errlen, |
| 536 | "bad ownership or modes for directory %s", buf); |
| 537 | return -1; |
| 538 | } |
| 539 | #endif |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 540 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 541 | /* If are past the homedir then we can stop */ |
| 542 | if (comparehome && strcmp(homedir, buf) == 0) |
| 543 | break; |
| 544 | |
| 545 | /* |
| 546 | * dirname should always complete with a "/" path, |
| 547 | * but we can be paranoid and check for "." too |
| 548 | */ |
| 549 | if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) |
| 550 | break; |
| 551 | } |
| 552 | return 0; |
| 553 | } |
| 554 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 555 | /* |
| 556 | * Version of secure_path() that accepts an open file descriptor to |
| 557 | * avoid races. |
| 558 | * |
| 559 | * Returns 0 on success and -1 on failure |
| 560 | */ |
| 561 | static int |
| 562 | secure_filename(FILE *f, const char *file, struct passwd *pw, |
| 563 | char *err, size_t errlen) |
| 564 | { |
| 565 | struct stat st; |
| 566 | |
| 567 | /* check the open file to avoid races */ |
| 568 | if (fstat(fileno(f), &st) < 0) { |
| 569 | snprintf(err, errlen, "cannot stat file %s: %s", |
| 570 | file, strerror(errno)); |
| 571 | return -1; |
| 572 | } |
| 573 | return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen); |
| 574 | } |
| 575 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 576 | static FILE * |
| 577 | auth_openfile(const char *file, struct passwd *pw, int strict_modes, |
| 578 | int log_missing, char *file_type) |
| 579 | { |
| 580 | char line[1024]; |
| 581 | struct stat st; |
| 582 | int fd; |
| 583 | FILE *f; |
| 584 | |
| 585 | if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) { |
| 586 | if (log_missing || errno != ENOENT) |
| 587 | debug("Could not open %s '%s': %s", file_type, file, |
| 588 | strerror(errno)); |
| 589 | return NULL; |
| 590 | } |
| 591 | |
| 592 | if (fstat(fd, &st) < 0) { |
| 593 | close(fd); |
| 594 | return NULL; |
| 595 | } |
| 596 | if (!S_ISREG(st.st_mode)) { |
| 597 | logit("User %s %s %s is not a regular file", |
| 598 | pw->pw_name, file_type, file); |
| 599 | close(fd); |
| 600 | return NULL; |
| 601 | } |
| 602 | unset_nonblock(fd); |
| 603 | if ((f = fdopen(fd, "r")) == NULL) { |
| 604 | close(fd); |
| 605 | return NULL; |
| 606 | } |
| 607 | if (strict_modes && |
| 608 | secure_filename(f, file, pw, line, sizeof(line)) != 0) { |
| 609 | fclose(f); |
| 610 | logit("Authentication refused: %s", line); |
| 611 | auth_debug_add("Ignored %s: %s", file_type, line); |
| 612 | return NULL; |
| 613 | } |
| 614 | |
| 615 | return f; |
| 616 | } |
| 617 | |
| 618 | |
| 619 | FILE * |
| 620 | auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes) |
| 621 | { |
| 622 | return auth_openfile(file, pw, strict_modes, 1, "authorized keys"); |
| 623 | } |
| 624 | |
| 625 | FILE * |
| 626 | auth_openprincipals(const char *file, struct passwd *pw, int strict_modes) |
| 627 | { |
| 628 | return auth_openfile(file, pw, strict_modes, 0, |
| 629 | "authorized principals"); |
| 630 | } |
| 631 | |
| 632 | struct passwd * |
| 633 | getpwnamallow(const char *user) |
| 634 | { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 635 | struct ssh *ssh = active_state; /* XXX */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 636 | #ifdef HAVE_LOGIN_CAP |
| 637 | extern login_cap_t *lc; |
| 638 | #ifdef BSD_AUTH |
| 639 | auth_session_t *as; |
| 640 | #endif |
| 641 | #endif |
| 642 | struct passwd *pw; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 643 | struct connection_info *ci = get_connection_info(1, options.use_dns); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 644 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 645 | ci->user = user; |
| 646 | parse_server_match_config(&options, ci); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 647 | |
| 648 | #if defined(_AIX) && defined(HAVE_SETAUTHDB) |
| 649 | aix_setauthdb(user); |
| 650 | #endif |
| 651 | |
Greg Hartman | e7f7ce9 | 2016-06-10 14:05:35 -0700 | [diff] [blame] | 652 | #if defined(ANDROID) |
Greg Hartman | 95194cb | 2015-11-10 13:41:08 -0800 | [diff] [blame] | 653 | // Android has a fixed set of users. Any incoming user that we can't |
| 654 | // identify should be authenticated as the shell user. |
| 655 | if (strcmp(user, "root") && strcmp(user, "shell")) { |
| 656 | logit("Login name %.100s forced to shell", user); |
| 657 | user = "shell"; |
| 658 | } |
| 659 | #endif |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 660 | pw = getpwnam(user); |
| 661 | |
| 662 | #if defined(_AIX) && defined(HAVE_SETAUTHDB) |
| 663 | aix_restoreauthdb(); |
| 664 | #endif |
| 665 | #ifdef HAVE_CYGWIN |
| 666 | /* |
| 667 | * Windows usernames are case-insensitive. To avoid later problems |
| 668 | * when trying to match the username, the user is only allowed to |
| 669 | * login if the username is given in the same case as stored in the |
| 670 | * user database. |
| 671 | */ |
| 672 | if (pw != NULL && strcmp(user, pw->pw_name) != 0) { |
| 673 | logit("Login name %.100s does not match stored username %.100s", |
| 674 | user, pw->pw_name); |
| 675 | pw = NULL; |
| 676 | } |
| 677 | #endif |
| 678 | if (pw == NULL) { |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 679 | logit("Invalid user %.100s from %.100s port %d", |
| 680 | user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 681 | #ifdef CUSTOM_FAILED_LOGIN |
| 682 | record_failed_login(user, |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 683 | auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 684 | #endif |
| 685 | #ifdef SSH_AUDIT_EVENTS |
| 686 | audit_event(SSH_INVALID_USER); |
| 687 | #endif /* SSH_AUDIT_EVENTS */ |
| 688 | return (NULL); |
| 689 | } |
| 690 | if (!allowed_user(pw)) |
| 691 | return (NULL); |
| 692 | #ifdef HAVE_LOGIN_CAP |
| 693 | if ((lc = login_getclass(pw->pw_class)) == NULL) { |
| 694 | debug("unable to get login class: %s", user); |
| 695 | return (NULL); |
| 696 | } |
| 697 | #ifdef BSD_AUTH |
| 698 | if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || |
| 699 | auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { |
| 700 | debug("Approval failure for %s", user); |
| 701 | pw = NULL; |
| 702 | } |
| 703 | if (as != NULL) |
| 704 | auth_close(as); |
| 705 | #endif |
| 706 | #endif |
| 707 | if (pw != NULL) |
| 708 | return (pwcopy(pw)); |
| 709 | return (NULL); |
| 710 | } |
| 711 | |
| 712 | /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */ |
| 713 | int |
| 714 | auth_key_is_revoked(Key *key) |
| 715 | { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 716 | char *fp = NULL; |
| 717 | int r; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 718 | |
| 719 | if (options.revoked_keys_file == NULL) |
| 720 | return 0; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 721 | if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, |
| 722 | SSH_FP_DEFAULT)) == NULL) { |
| 723 | r = SSH_ERR_ALLOC_FAIL; |
| 724 | error("%s: fingerprint key: %s", __func__, ssh_err(r)); |
| 725 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 726 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 727 | |
| 728 | r = sshkey_check_revoked(key, options.revoked_keys_file); |
| 729 | switch (r) { |
| 730 | case 0: |
| 731 | break; /* not revoked */ |
| 732 | case SSH_ERR_KEY_REVOKED: |
| 733 | error("Authentication key %s %s revoked by file %s", |
| 734 | sshkey_type(key), fp, options.revoked_keys_file); |
| 735 | goto out; |
| 736 | default: |
| 737 | error("Error checking authentication key %s %s in " |
| 738 | "revoked keys file %s: %s", sshkey_type(key), fp, |
| 739 | options.revoked_keys_file, ssh_err(r)); |
| 740 | goto out; |
| 741 | } |
| 742 | |
| 743 | /* Success */ |
| 744 | r = 0; |
| 745 | |
| 746 | out: |
| 747 | free(fp); |
| 748 | return r == 0 ? 0 : 1; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 749 | } |
| 750 | |
| 751 | void |
| 752 | auth_debug_add(const char *fmt,...) |
| 753 | { |
| 754 | char buf[1024]; |
| 755 | va_list args; |
| 756 | |
| 757 | if (!auth_debug_init) |
| 758 | return; |
| 759 | |
| 760 | va_start(args, fmt); |
| 761 | vsnprintf(buf, sizeof(buf), fmt, args); |
| 762 | va_end(args); |
| 763 | buffer_put_cstring(&auth_debug, buf); |
| 764 | } |
| 765 | |
| 766 | void |
| 767 | auth_debug_send(void) |
| 768 | { |
| 769 | char *msg; |
| 770 | |
| 771 | if (!auth_debug_init) |
| 772 | return; |
| 773 | while (buffer_len(&auth_debug)) { |
| 774 | msg = buffer_get_string(&auth_debug, NULL); |
| 775 | packet_send_debug("%s", msg); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 776 | free(msg); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 777 | } |
| 778 | } |
| 779 | |
| 780 | void |
| 781 | auth_debug_reset(void) |
| 782 | { |
| 783 | if (auth_debug_init) |
| 784 | buffer_clear(&auth_debug); |
| 785 | else { |
| 786 | buffer_init(&auth_debug); |
| 787 | auth_debug_init = 1; |
| 788 | } |
| 789 | } |
| 790 | |
| 791 | struct passwd * |
| 792 | fakepw(void) |
| 793 | { |
| 794 | static struct passwd fake; |
| 795 | |
| 796 | memset(&fake, 0, sizeof(fake)); |
| 797 | fake.pw_name = "NOUSER"; |
| 798 | fake.pw_passwd = |
| 799 | "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK"; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 800 | #ifdef HAVE_STRUCT_PASSWD_PW_GECOS |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 801 | fake.pw_gecos = "NOUSER"; |
| 802 | #endif |
| 803 | fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid; |
| 804 | fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 805 | #ifdef HAVE_STRUCT_PASSWD_PW_CLASS |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 806 | fake.pw_class = ""; |
| 807 | #endif |
| 808 | fake.pw_dir = "/nonexist"; |
| 809 | fake.pw_shell = "/nonexist"; |
| 810 | |
| 811 | return (&fake); |
| 812 | } |
Greg Hartman | 9768ca4 | 2017-06-22 20:49:52 -0700 | [diff] [blame] | 813 | |
| 814 | /* |
| 815 | * Returns the remote DNS hostname as a string. The returned string must not |
| 816 | * be freed. NB. this will usually trigger a DNS query the first time it is |
| 817 | * called. |
| 818 | * This function does additional checks on the hostname to mitigate some |
| 819 | * attacks on legacy rhosts-style authentication. |
| 820 | * XXX is RhostsRSAAuthentication vulnerable to these? |
| 821 | * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?) |
| 822 | */ |
| 823 | |
| 824 | static char * |
| 825 | remote_hostname(struct ssh *ssh) |
| 826 | { |
| 827 | struct sockaddr_storage from; |
| 828 | socklen_t fromlen; |
| 829 | struct addrinfo hints, *ai, *aitop; |
| 830 | char name[NI_MAXHOST], ntop2[NI_MAXHOST]; |
| 831 | const char *ntop = ssh_remote_ipaddr(ssh); |
| 832 | |
| 833 | /* Get IP address of client. */ |
| 834 | fromlen = sizeof(from); |
| 835 | memset(&from, 0, sizeof(from)); |
| 836 | if (getpeername(ssh_packet_get_connection_in(ssh), |
| 837 | (struct sockaddr *)&from, &fromlen) < 0) { |
| 838 | debug("getpeername failed: %.100s", strerror(errno)); |
| 839 | return strdup(ntop); |
| 840 | } |
| 841 | |
| 842 | ipv64_normalise_mapped(&from, &fromlen); |
| 843 | if (from.ss_family == AF_INET6) |
| 844 | fromlen = sizeof(struct sockaddr_in6); |
| 845 | |
| 846 | debug3("Trying to reverse map address %.100s.", ntop); |
| 847 | /* Map the IP address to a host name. */ |
| 848 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), |
| 849 | NULL, 0, NI_NAMEREQD) != 0) { |
| 850 | /* Host name not found. Use ip address. */ |
| 851 | return strdup(ntop); |
| 852 | } |
| 853 | |
| 854 | /* |
| 855 | * if reverse lookup result looks like a numeric hostname, |
| 856 | * someone is trying to trick us by PTR record like following: |
| 857 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 |
| 858 | */ |
| 859 | memset(&hints, 0, sizeof(hints)); |
| 860 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ |
| 861 | hints.ai_flags = AI_NUMERICHOST; |
| 862 | if (getaddrinfo(name, NULL, &hints, &ai) == 0) { |
| 863 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", |
| 864 | name, ntop); |
| 865 | freeaddrinfo(ai); |
| 866 | return strdup(ntop); |
| 867 | } |
| 868 | |
| 869 | /* Names are stored in lowercase. */ |
| 870 | lowercase(name); |
| 871 | |
| 872 | /* |
| 873 | * Map it back to an IP address and check that the given |
| 874 | * address actually is an address of this host. This is |
| 875 | * necessary because anyone with access to a name server can |
| 876 | * define arbitrary names for an IP address. Mapping from |
| 877 | * name to IP address can be trusted better (but can still be |
| 878 | * fooled if the intruder has access to the name server of |
| 879 | * the domain). |
| 880 | */ |
| 881 | memset(&hints, 0, sizeof(hints)); |
| 882 | hints.ai_family = from.ss_family; |
| 883 | hints.ai_socktype = SOCK_STREAM; |
| 884 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { |
| 885 | logit("reverse mapping checking getaddrinfo for %.700s " |
| 886 | "[%s] failed.", name, ntop); |
| 887 | return strdup(ntop); |
| 888 | } |
| 889 | /* Look for the address from the list of addresses. */ |
| 890 | for (ai = aitop; ai; ai = ai->ai_next) { |
| 891 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, |
| 892 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && |
| 893 | (strcmp(ntop, ntop2) == 0)) |
| 894 | break; |
| 895 | } |
| 896 | freeaddrinfo(aitop); |
| 897 | /* If we reached the end of the list, the address was not there. */ |
| 898 | if (ai == NULL) { |
| 899 | /* Address not found for the host name. */ |
| 900 | logit("Address %.100s maps to %.600s, but this does not " |
| 901 | "map back to the address.", ntop, name); |
| 902 | return strdup(ntop); |
| 903 | } |
| 904 | return strdup(name); |
| 905 | } |
| 906 | |
| 907 | /* |
| 908 | * Return the canonical name of the host in the other side of the current |
| 909 | * connection. The host name is cached, so it is efficient to call this |
| 910 | * several times. |
| 911 | */ |
| 912 | |
| 913 | const char * |
| 914 | auth_get_canonical_hostname(struct ssh *ssh, int use_dns) |
| 915 | { |
| 916 | static char *dnsname; |
| 917 | |
| 918 | if (!use_dns) |
| 919 | return ssh_remote_ipaddr(ssh); |
| 920 | else if (dnsname != NULL) |
| 921 | return dnsname; |
| 922 | else { |
| 923 | dnsname = remote_hostname(ssh); |
| 924 | return dnsname; |
| 925 | } |
| 926 | } |