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7368a6c8 | 1 | /* |
f3c7c613 | 2 | * Copyright (c) 2000 Markus Friedl. All rights reserved. |
bcbf86ec | 3 | * |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
7368a6c8 | 23 | */ |
24 | ||
25 | #include "includes.h" | |
06bea668 | 26 | RCSID("$OpenBSD: auth.c,v 1.41 2002/03/19 15:31:47 markus Exp $"); |
7368a6c8 | 27 | |
c1ef8333 | 28 | #ifdef HAVE_LOGIN_H |
29 | #include <login.h> | |
30 | #endif | |
4cb5ffa0 | 31 | #if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) |
32 | #include <shadow.h> | |
33 | #endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */ | |
7368a6c8 | 34 | |
b4d02860 | 35 | #ifdef HAVE_LIBGEN_H |
c8445989 | 36 | #include <libgen.h> |
b4d02860 | 37 | #endif |
c8445989 | 38 | |
42f11eb2 | 39 | #include "xmalloc.h" |
40 | #include "match.h" | |
41 | #include "groupaccess.h" | |
42 | #include "log.h" | |
43 | #include "servconf.h" | |
e78a59f5 | 44 | #include "auth.h" |
59c97189 | 45 | #include "auth-options.h" |
42f11eb2 | 46 | #include "canohost.h" |
c8445989 | 47 | #include "buffer.h" |
48 | #include "bufaux.h" | |
d0c8ca5c | 49 | #include "uidswap.h" |
50 | #include "tildexpand.h" | |
5f1f36b5 | 51 | #include "misc.h" |
e78a59f5 | 52 | |
7368a6c8 | 53 | /* import */ |
54 | extern ServerOptions options; | |
7368a6c8 | 55 | |
56 | /* | |
c6a69271 | 57 | * Check if the user is allowed to log in via ssh. If user is listed |
58 | * in DenyUsers or one of user's groups is listed in DenyGroups, false | |
59 | * will be returned. If AllowUsers isn't empty and user isn't listed | |
60 | * there, or if AllowGroups isn't empty and one of user's groups isn't | |
61 | * listed there, false will be returned. | |
7368a6c8 | 62 | * If the user's shell is not executable, false will be returned. |
6ae2364d | 63 | * Otherwise true is returned. |
7368a6c8 | 64 | */ |
a306f2dd | 65 | int |
7368a6c8 | 66 | allowed_user(struct passwd * pw) |
67 | { | |
68 | struct stat st; | |
6805fc56 | 69 | const char *hostname = NULL, *ipaddr = NULL; |
614dee3a | 70 | char *shell; |
7368a6c8 | 71 | int i; |
72 | #ifdef WITH_AIXAUTHENTICATE | |
73 | char *loginmsg; | |
74 | #endif /* WITH_AIXAUTHENTICATE */ | |
75b90ced | 75 | #if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \ |
37c1c46d | 76 | !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE) |
c6a69271 | 77 | struct spwd *spw; |
7368a6c8 | 78 | |
79 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ | |
c6a69271 | 80 | if (!pw || !pw->pw_name) |
7368a6c8 | 81 | return 0; |
82 | ||
5b29f152 | 83 | #define DAY (24L * 60 * 60) /* 1 day in seconds */ |
4cb5ffa0 | 84 | spw = getspnam(pw->pw_name); |
27494968 | 85 | if (spw != NULL) { |
5b29f152 | 86 | time_t today = time(NULL) / DAY; |
87 | debug3("allowed_user: today %d sp_expire %d sp_lstchg %d" | |
88 | " sp_max %d", (int)today, (int)spw->sp_expire, | |
89 | (int)spw->sp_lstchg, (int)spw->sp_max); | |
4cb5ffa0 | 90 | |
5b29f152 | 91 | /* |
92 | * We assume account and password expiration occurs the | |
93 | * day after the day specified. | |
94 | */ | |
95 | if (spw->sp_expire != -1 && today > spw->sp_expire) { | |
96 | log("Account %.100s has expired", pw->pw_name); | |
27494968 | 97 | return 0; |
5b29f152 | 98 | } |
27494968 | 99 | |
5b29f152 | 100 | if (spw->sp_lstchg == 0) { |
101 | log("User %.100s password has expired (root forced)", | |
102 | pw->pw_name); | |
27494968 | 103 | return 0; |
5b29f152 | 104 | } |
105 | ||
106 | if (spw->sp_max != -1 && | |
107 | today > spw->sp_lstchg + spw->sp_max) { | |
108 | log("User %.100s password has expired (password aged)", | |
109 | pw->pw_name); | |
110 | return 0; | |
111 | } | |
27494968 | 112 | } |
4cb5ffa0 | 113 | #else |
114 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ | |
c6a69271 | 115 | if (!pw || !pw->pw_name) |
4cb5ffa0 | 116 | return 0; |
117 | #endif | |
118 | ||
301e9b01 | 119 | /* |
120 | * Get the shell from the password data. An empty shell field is | |
121 | * legal, and means /bin/sh. | |
122 | */ | |
123 | shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; | |
124 | ||
125 | /* deny if shell does not exists or is not executable */ | |
b334badd | 126 | if (stat(shell, &st) != 0) { |
127 | log("User %.100s not allowed because shell %.100s does not exist", | |
128 | pw->pw_name, shell); | |
7368a6c8 | 129 | return 0; |
b334badd | 130 | } |
c390a3c8 | 131 | if (S_ISREG(st.st_mode) == 0 || |
132 | (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { | |
b334badd | 133 | log("User %.100s not allowed because shell %.100s is not executable", |
134 | pw->pw_name, shell); | |
7368a6c8 | 135 | return 0; |
b334badd | 136 | } |
7368a6c8 | 137 | |
6805fc56 | 138 | if (options.num_deny_users > 0 || options.num_allow_users > 0) { |
139 | hostname = get_canonical_hostname(options.verify_reverse_mapping); | |
140 | ipaddr = get_remote_ipaddr(); | |
141 | } | |
142 | ||
7368a6c8 | 143 | /* Return false if user is listed in DenyUsers */ |
144 | if (options.num_deny_users > 0) { | |
7368a6c8 | 145 | for (i = 0; i < options.num_deny_users; i++) |
762715ce | 146 | if (match_user(pw->pw_name, hostname, ipaddr, |
b334badd | 147 | options.deny_users[i])) { |
762715ce | 148 | log("User %.100s not allowed because listed in DenyUsers", |
149 | pw->pw_name); | |
7368a6c8 | 150 | return 0; |
b334badd | 151 | } |
7368a6c8 | 152 | } |
153 | /* Return false if AllowUsers isn't empty and user isn't listed there */ | |
154 | if (options.num_allow_users > 0) { | |
7368a6c8 | 155 | for (i = 0; i < options.num_allow_users; i++) |
762715ce | 156 | if (match_user(pw->pw_name, hostname, ipaddr, |
80f8f24f | 157 | options.allow_users[i])) |
7368a6c8 | 158 | break; |
159 | /* i < options.num_allow_users iff we break for loop */ | |
b334badd | 160 | if (i >= options.num_allow_users) { |
161 | log("User %.100s not allowed because not listed in AllowUsers", | |
162 | pw->pw_name); | |
7368a6c8 | 163 | return 0; |
b334badd | 164 | } |
7368a6c8 | 165 | } |
7368a6c8 | 166 | if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
c6a69271 | 167 | /* Get the user's group access list (primary and supplementary) */ |
b334badd | 168 | if (ga_init(pw->pw_name, pw->pw_gid) == 0) { |
169 | log("User %.100s not allowed because not in any group", | |
170 | pw->pw_name); | |
7368a6c8 | 171 | return 0; |
b334badd | 172 | } |
7368a6c8 | 173 | |
c6a69271 | 174 | /* Return false if one of user's groups is listed in DenyGroups */ |
175 | if (options.num_deny_groups > 0) | |
176 | if (ga_match(options.deny_groups, | |
177 | options.num_deny_groups)) { | |
178 | ga_free(); | |
b334badd | 179 | log("User %.100s not allowed because a group is listed in DenyGroups", |
180 | pw->pw_name); | |
7368a6c8 | 181 | return 0; |
c6a69271 | 182 | } |
7368a6c8 | 183 | /* |
c6a69271 | 184 | * Return false if AllowGroups isn't empty and one of user's groups |
7368a6c8 | 185 | * isn't listed there |
186 | */ | |
c6a69271 | 187 | if (options.num_allow_groups > 0) |
188 | if (!ga_match(options.allow_groups, | |
189 | options.num_allow_groups)) { | |
190 | ga_free(); | |
b334badd | 191 | log("User %.100s not allowed because none of user's groups are listed in AllowGroups", |
192 | pw->pw_name); | |
7368a6c8 | 193 | return 0; |
c6a69271 | 194 | } |
195 | ga_free(); | |
7368a6c8 | 196 | } |
197 | ||
198 | #ifdef WITH_AIXAUTHENTICATE | |
5daf7064 | 199 | if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) { |
c1ef8333 | 200 | if (loginmsg && *loginmsg) { |
201 | /* Remove embedded newlines (if any) */ | |
202 | char *p; | |
5daf7064 | 203 | for (p = loginmsg; *p; p++) { |
c1ef8333 | 204 | if (*p == '\n') |
205 | *p = ' '; | |
5daf7064 | 206 | } |
c1ef8333 | 207 | /* Remove trailing newline */ |
208 | *--p = '\0'; | |
5daf7064 | 209 | log("Login restricted for %s: %.100s", pw->pw_name, loginmsg); |
c1ef8333 | 210 | } |
7368a6c8 | 211 | return 0; |
c1ef8333 | 212 | } |
7368a6c8 | 213 | #endif /* WITH_AIXAUTHENTICATE */ |
214 | ||
215 | /* We found no reason not to let this user try to log on... */ | |
216 | return 1; | |
217 | } | |
59c97189 | 218 | |
219 | Authctxt * | |
220 | authctxt_new(void) | |
221 | { | |
2b87da3b | 222 | Authctxt *authctxt = xmalloc(sizeof(*authctxt)); |
223 | memset(authctxt, 0, sizeof(*authctxt)); | |
224 | return authctxt; | |
59c97189 | 225 | } |
226 | ||
59c97189 | 227 | void |
228 | auth_log(Authctxt *authctxt, int authenticated, char *method, char *info) | |
229 | { | |
230 | void (*authlog) (const char *fmt,...) = verbose; | |
231 | char *authmsg; | |
232 | ||
233 | /* Raise logging level */ | |
234 | if (authenticated == 1 || | |
235 | !authctxt->valid || | |
236 | authctxt->failures >= AUTH_FAIL_LOG || | |
237 | strcmp(method, "password") == 0) | |
238 | authlog = log; | |
239 | ||
240 | if (authctxt->postponed) | |
241 | authmsg = "Postponed"; | |
242 | else | |
243 | authmsg = authenticated ? "Accepted" : "Failed"; | |
244 | ||
245 | authlog("%s %s for %s%.100s from %.200s port %d%s", | |
246 | authmsg, | |
247 | method, | |
248 | authctxt->valid ? "" : "illegal user ", | |
fad3754c | 249 | authctxt->user, |
59c97189 | 250 | get_remote_ipaddr(), |
251 | get_remote_port(), | |
252 | info); | |
253 | } | |
254 | ||
255 | /* | |
15853e93 | 256 | * Check whether root logins are disallowed. |
59c97189 | 257 | */ |
258 | int | |
15853e93 | 259 | auth_root_allowed(char *method) |
59c97189 | 260 | { |
15853e93 | 261 | switch (options.permit_root_login) { |
262 | case PERMIT_YES: | |
59c97189 | 263 | return 1; |
15853e93 | 264 | break; |
265 | case PERMIT_NO_PASSWD: | |
266 | if (strcmp(method, "password") != 0) | |
267 | return 1; | |
268 | break; | |
269 | case PERMIT_FORCED_ONLY: | |
270 | if (forced_command) { | |
271 | log("Root login accepted for forced command."); | |
272 | return 1; | |
273 | } | |
274 | break; | |
59c97189 | 275 | } |
15853e93 | 276 | log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr()); |
277 | return 0; | |
59c97189 | 278 | } |
c8445989 | 279 | |
280 | ||
281 | /* | |
282 | * Given a template and a passwd structure, build a filename | |
283 | * by substituting % tokenised options. Currently, %% becomes '%', | |
284 | * %h becomes the home directory and %u the username. | |
285 | * | |
286 | * This returns a buffer allocated by xmalloc. | |
287 | */ | |
288 | char * | |
289 | expand_filename(const char *filename, struct passwd *pw) | |
290 | { | |
291 | Buffer buffer; | |
292 | char *file; | |
293 | const char *cp; | |
294 | ||
295 | /* | |
296 | * Build the filename string in the buffer by making the appropriate | |
297 | * substitutions to the given file name. | |
298 | */ | |
299 | buffer_init(&buffer); | |
300 | for (cp = filename; *cp; cp++) { | |
301 | if (cp[0] == '%' && cp[1] == '%') { | |
302 | buffer_append(&buffer, "%", 1); | |
303 | cp++; | |
304 | continue; | |
305 | } | |
306 | if (cp[0] == '%' && cp[1] == 'h') { | |
307 | buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir)); | |
308 | cp++; | |
309 | continue; | |
310 | } | |
311 | if (cp[0] == '%' && cp[1] == 'u') { | |
312 | buffer_append(&buffer, pw->pw_name, | |
184eed6a | 313 | strlen(pw->pw_name)); |
c8445989 | 314 | cp++; |
315 | continue; | |
316 | } | |
317 | buffer_append(&buffer, cp, 1); | |
318 | } | |
319 | buffer_append(&buffer, "\0", 1); | |
320 | ||
321 | /* | |
322 | * Ensure that filename starts anchored. If not, be backward | |
323 | * compatible and prepend the '%h/' | |
324 | */ | |
325 | file = xmalloc(MAXPATHLEN); | |
326 | cp = buffer_ptr(&buffer); | |
327 | if (*cp != '/') | |
328 | snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp); | |
329 | else | |
330 | strlcpy(file, cp, MAXPATHLEN); | |
331 | ||
332 | buffer_free(&buffer); | |
333 | return file; | |
334 | } | |
335 | ||
336 | char * | |
337 | authorized_keys_file(struct passwd *pw) | |
338 | { | |
339 | return expand_filename(options.authorized_keys_file, pw); | |
340 | } | |
341 | ||
342 | char * | |
343 | authorized_keys_file2(struct passwd *pw) | |
344 | { | |
345 | return expand_filename(options.authorized_keys_file2, pw); | |
346 | } | |
347 | ||
d0c8ca5c | 348 | /* return ok if key exists in sysfile or userfile */ |
349 | HostStatus | |
350 | check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host, | |
351 | const char *sysfile, const char *userfile) | |
352 | { | |
353 | Key *found; | |
354 | char *user_hostfile; | |
355 | struct stat st; | |
17a3011c | 356 | HostStatus host_status; |
d0c8ca5c | 357 | |
358 | /* Check if we know the host and its host key. */ | |
359 | found = key_new(key->type); | |
360 | host_status = check_host_in_hostfile(sysfile, host, key, found, NULL); | |
361 | ||
362 | if (host_status != HOST_OK && userfile != NULL) { | |
363 | user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); | |
364 | if (options.strict_modes && | |
365 | (stat(user_hostfile, &st) == 0) && | |
366 | ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || | |
184eed6a | 367 | (st.st_mode & 022) != 0)) { |
d0c8ca5c | 368 | log("Authentication refused for %.100s: " |
369 | "bad owner or modes for %.200s", | |
370 | pw->pw_name, user_hostfile); | |
371 | } else { | |
372 | temporarily_use_uid(pw); | |
373 | host_status = check_host_in_hostfile(user_hostfile, | |
374 | host, key, found, NULL); | |
375 | restore_uid(); | |
376 | } | |
377 | xfree(user_hostfile); | |
378 | } | |
379 | key_free(found); | |
380 | ||
381 | debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ? | |
382 | "ok" : "not found", host); | |
383 | return host_status; | |
384 | } | |
385 | ||
386 | ||
c8445989 | 387 | /* |
388 | * Check a given file for security. This is defined as all components | |
389 | * of the path to the file must either be owned by either the owner of | |
1ddf764b | 390 | * of the file or root and no directories must be group or world writable. |
c8445989 | 391 | * |
392 | * XXX Should any specific check be done for sym links ? | |
393 | * | |
394 | * Takes an open file descriptor, the file name, a uid and and | |
395 | * error buffer plus max size as arguments. | |
396 | * | |
397 | * Returns 0 on success and -1 on failure | |
398 | */ | |
399 | int | |
6978866a | 400 | secure_filename(FILE *f, const char *file, struct passwd *pw, |
401 | char *err, size_t errlen) | |
c8445989 | 402 | { |
6978866a | 403 | uid_t uid = pw->pw_uid; |
76fbdd47 | 404 | char buf[MAXPATHLEN], homedir[MAXPATHLEN]; |
c8445989 | 405 | char *cp; |
406 | struct stat st; | |
407 | ||
408 | if (realpath(file, buf) == NULL) { | |
409 | snprintf(err, errlen, "realpath %s failed: %s", file, | |
410 | strerror(errno)); | |
411 | return -1; | |
412 | } | |
76fbdd47 | 413 | if (realpath(pw->pw_dir, homedir) == NULL) { |
414 | snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir, | |
415 | strerror(errno)); | |
416 | return -1; | |
417 | } | |
c8445989 | 418 | |
419 | /* check the open file to avoid races */ | |
420 | if (fstat(fileno(f), &st) < 0 || | |
421 | (st.st_uid != 0 && st.st_uid != uid) || | |
422 | (st.st_mode & 022) != 0) { | |
423 | snprintf(err, errlen, "bad ownership or modes for file %s", | |
424 | buf); | |
425 | return -1; | |
426 | } | |
427 | ||
428 | /* for each component of the canonical path, walking upwards */ | |
429 | for (;;) { | |
430 | if ((cp = dirname(buf)) == NULL) { | |
431 | snprintf(err, errlen, "dirname() failed"); | |
432 | return -1; | |
433 | } | |
434 | strlcpy(buf, cp, sizeof(buf)); | |
435 | ||
436 | debug3("secure_filename: checking '%s'", buf); | |
437 | if (stat(buf, &st) < 0 || | |
438 | (st.st_uid != 0 && st.st_uid != uid) || | |
439 | (st.st_mode & 022) != 0) { | |
184eed6a | 440 | snprintf(err, errlen, |
c8445989 | 441 | "bad ownership or modes for directory %s", buf); |
442 | return -1; | |
443 | } | |
444 | ||
afd501f9 | 445 | /* If are passed the homedir then we can stop */ |
76fbdd47 | 446 | if (strcmp(homedir, buf) == 0) { |
afd501f9 | 447 | debug3("secure_filename: terminating check at '%s'", |
448 | buf); | |
449 | break; | |
450 | } | |
c8445989 | 451 | /* |
452 | * dirname should always complete with a "/" path, | |
453 | * but we can be paranoid and check for "." too | |
454 | */ | |
455 | if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) | |
456 | break; | |
457 | } | |
458 | return 0; | |
459 | } | |
443fa1cd | 460 | |
461 | struct passwd * | |
462 | getpwnamallow(const char *user) | |
463 | { | |
1836f69f | 464 | #ifdef HAVE_LOGIN_CAP |
465 | extern login_cap_t *lc; | |
466 | #ifdef BSD_AUTH | |
467 | auth_session_t *as; | |
468 | #endif | |
469 | #endif | |
443fa1cd | 470 | struct passwd *pw; |
471 | ||
472 | pw = getpwnam(user); | |
1836f69f | 473 | if (pw == NULL || !allowed_user(pw)) |
474 | return (NULL); | |
475 | #ifdef HAVE_LOGIN_CAP | |
476 | if ((lc = login_getclass(pw->pw_class)) == NULL) { | |
477 | debug("unable to get login class: %s", user); | |
478 | return (NULL); | |
479 | } | |
480 | #ifdef BSD_AUTH | |
481 | if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || | |
482 | auth_approval(NULL, lc, pw->pw_name, "ssh") <= 0) { | |
483 | debug("Approval failure for %s", user); | |
443fa1cd | 484 | pw = NULL; |
1836f69f | 485 | } |
486 | if (as != NULL) | |
487 | auth_close(as); | |
488 | #endif | |
489 | #endif | |
06bea668 | 490 | if (pw != NULL) |
491 | return (pwcopy(pw)); | |
492 | return (NULL); | |
443fa1cd | 493 | } |