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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" | |
1ddf764b | 26 | RCSID("$OpenBSD: auth.c,v 1.23 2001/05/24 11:12:42 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 | |
c8445989 | 35 | #include <libgen.h> |
36 | ||
42f11eb2 | 37 | #include "xmalloc.h" |
38 | #include "match.h" | |
39 | #include "groupaccess.h" | |
40 | #include "log.h" | |
41 | #include "servconf.h" | |
e78a59f5 | 42 | #include "auth.h" |
59c97189 | 43 | #include "auth-options.h" |
42f11eb2 | 44 | #include "canohost.h" |
c8445989 | 45 | #include "buffer.h" |
46 | #include "bufaux.h" | |
e78a59f5 | 47 | |
7368a6c8 | 48 | /* import */ |
49 | extern ServerOptions options; | |
7368a6c8 | 50 | |
51 | /* | |
c6a69271 | 52 | * Check if the user is allowed to log in via ssh. If user is listed |
53 | * in DenyUsers or one of user's groups is listed in DenyGroups, false | |
54 | * will be returned. If AllowUsers isn't empty and user isn't listed | |
55 | * there, or if AllowGroups isn't empty and one of user's groups isn't | |
56 | * listed there, false will be returned. | |
7368a6c8 | 57 | * If the user's shell is not executable, false will be returned. |
6ae2364d | 58 | * Otherwise true is returned. |
7368a6c8 | 59 | */ |
a306f2dd | 60 | int |
7368a6c8 | 61 | allowed_user(struct passwd * pw) |
62 | { | |
63 | struct stat st; | |
614dee3a | 64 | char *shell; |
7368a6c8 | 65 | int i; |
66 | #ifdef WITH_AIXAUTHENTICATE | |
67 | char *loginmsg; | |
68 | #endif /* WITH_AIXAUTHENTICATE */ | |
75b90ced | 69 | #if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \ |
37c1c46d | 70 | !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE) |
c6a69271 | 71 | struct spwd *spw; |
7368a6c8 | 72 | |
73 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ | |
c6a69271 | 74 | if (!pw || !pw->pw_name) |
7368a6c8 | 75 | return 0; |
76 | ||
4cb5ffa0 | 77 | spw = getspnam(pw->pw_name); |
27494968 | 78 | if (spw != NULL) { |
79 | int days = time(NULL) / 86400; | |
4cb5ffa0 | 80 | |
27494968 | 81 | /* Check account expiry */ |
37c1c46d | 82 | if ((spw->sp_expire >= 0) && (days > spw->sp_expire)) |
27494968 | 83 | return 0; |
84 | ||
85 | /* Check password expiry */ | |
2b87da3b | 86 | if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) && |
7f8f5e00 | 87 | (days > (spw->sp_lstchg + spw->sp_max))) |
27494968 | 88 | return 0; |
89 | } | |
4cb5ffa0 | 90 | #else |
91 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ | |
c6a69271 | 92 | if (!pw || !pw->pw_name) |
4cb5ffa0 | 93 | return 0; |
94 | #endif | |
95 | ||
301e9b01 | 96 | /* |
97 | * Get the shell from the password data. An empty shell field is | |
98 | * legal, and means /bin/sh. | |
99 | */ | |
100 | shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; | |
101 | ||
102 | /* deny if shell does not exists or is not executable */ | |
103 | if (stat(shell, &st) != 0) | |
7368a6c8 | 104 | return 0; |
105 | if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)))) | |
106 | return 0; | |
107 | ||
108 | /* Return false if user is listed in DenyUsers */ | |
109 | if (options.num_deny_users > 0) { | |
7368a6c8 | 110 | for (i = 0; i < options.num_deny_users; i++) |
111 | if (match_pattern(pw->pw_name, options.deny_users[i])) | |
112 | return 0; | |
113 | } | |
114 | /* Return false if AllowUsers isn't empty and user isn't listed there */ | |
115 | if (options.num_allow_users > 0) { | |
7368a6c8 | 116 | for (i = 0; i < options.num_allow_users; i++) |
117 | if (match_pattern(pw->pw_name, options.allow_users[i])) | |
118 | break; | |
119 | /* i < options.num_allow_users iff we break for loop */ | |
120 | if (i >= options.num_allow_users) | |
121 | return 0; | |
122 | } | |
7368a6c8 | 123 | if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
c6a69271 | 124 | /* Get the user's group access list (primary and supplementary) */ |
125 | if (ga_init(pw->pw_name, pw->pw_gid) == 0) | |
7368a6c8 | 126 | return 0; |
127 | ||
c6a69271 | 128 | /* Return false if one of user's groups is listed in DenyGroups */ |
129 | if (options.num_deny_groups > 0) | |
130 | if (ga_match(options.deny_groups, | |
131 | options.num_deny_groups)) { | |
132 | ga_free(); | |
7368a6c8 | 133 | return 0; |
c6a69271 | 134 | } |
7368a6c8 | 135 | /* |
c6a69271 | 136 | * Return false if AllowGroups isn't empty and one of user's groups |
7368a6c8 | 137 | * isn't listed there |
138 | */ | |
c6a69271 | 139 | if (options.num_allow_groups > 0) |
140 | if (!ga_match(options.allow_groups, | |
141 | options.num_allow_groups)) { | |
142 | ga_free(); | |
7368a6c8 | 143 | return 0; |
c6a69271 | 144 | } |
145 | ga_free(); | |
7368a6c8 | 146 | } |
147 | ||
148 | #ifdef WITH_AIXAUTHENTICATE | |
5daf7064 | 149 | if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) { |
c1ef8333 | 150 | if (loginmsg && *loginmsg) { |
151 | /* Remove embedded newlines (if any) */ | |
152 | char *p; | |
5daf7064 | 153 | for (p = loginmsg; *p; p++) { |
c1ef8333 | 154 | if (*p == '\n') |
155 | *p = ' '; | |
5daf7064 | 156 | } |
c1ef8333 | 157 | /* Remove trailing newline */ |
158 | *--p = '\0'; | |
5daf7064 | 159 | log("Login restricted for %s: %.100s", pw->pw_name, loginmsg); |
c1ef8333 | 160 | } |
7368a6c8 | 161 | return 0; |
c1ef8333 | 162 | } |
7368a6c8 | 163 | #endif /* WITH_AIXAUTHENTICATE */ |
164 | ||
165 | /* We found no reason not to let this user try to log on... */ | |
166 | return 1; | |
167 | } | |
59c97189 | 168 | |
169 | Authctxt * | |
170 | authctxt_new(void) | |
171 | { | |
2b87da3b | 172 | Authctxt *authctxt = xmalloc(sizeof(*authctxt)); |
173 | memset(authctxt, 0, sizeof(*authctxt)); | |
174 | return authctxt; | |
59c97189 | 175 | } |
176 | ||
59c97189 | 177 | void |
178 | auth_log(Authctxt *authctxt, int authenticated, char *method, char *info) | |
179 | { | |
180 | void (*authlog) (const char *fmt,...) = verbose; | |
181 | char *authmsg; | |
182 | ||
183 | /* Raise logging level */ | |
184 | if (authenticated == 1 || | |
185 | !authctxt->valid || | |
186 | authctxt->failures >= AUTH_FAIL_LOG || | |
187 | strcmp(method, "password") == 0) | |
188 | authlog = log; | |
189 | ||
190 | if (authctxt->postponed) | |
191 | authmsg = "Postponed"; | |
192 | else | |
193 | authmsg = authenticated ? "Accepted" : "Failed"; | |
194 | ||
195 | authlog("%s %s for %s%.100s from %.200s port %d%s", | |
196 | authmsg, | |
197 | method, | |
198 | authctxt->valid ? "" : "illegal user ", | |
199 | authctxt->valid && authctxt->pw->pw_uid == 0 ? "ROOT" : authctxt->user, | |
200 | get_remote_ipaddr(), | |
201 | get_remote_port(), | |
202 | info); | |
203 | } | |
204 | ||
205 | /* | |
15853e93 | 206 | * Check whether root logins are disallowed. |
59c97189 | 207 | */ |
208 | int | |
15853e93 | 209 | auth_root_allowed(char *method) |
59c97189 | 210 | { |
15853e93 | 211 | switch (options.permit_root_login) { |
212 | case PERMIT_YES: | |
59c97189 | 213 | return 1; |
15853e93 | 214 | break; |
215 | case PERMIT_NO_PASSWD: | |
216 | if (strcmp(method, "password") != 0) | |
217 | return 1; | |
218 | break; | |
219 | case PERMIT_FORCED_ONLY: | |
220 | if (forced_command) { | |
221 | log("Root login accepted for forced command."); | |
222 | return 1; | |
223 | } | |
224 | break; | |
59c97189 | 225 | } |
15853e93 | 226 | log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr()); |
227 | return 0; | |
59c97189 | 228 | } |
c8445989 | 229 | |
230 | ||
231 | /* | |
232 | * Given a template and a passwd structure, build a filename | |
233 | * by substituting % tokenised options. Currently, %% becomes '%', | |
234 | * %h becomes the home directory and %u the username. | |
235 | * | |
236 | * This returns a buffer allocated by xmalloc. | |
237 | */ | |
238 | char * | |
239 | expand_filename(const char *filename, struct passwd *pw) | |
240 | { | |
241 | Buffer buffer; | |
242 | char *file; | |
243 | const char *cp; | |
244 | ||
245 | /* | |
246 | * Build the filename string in the buffer by making the appropriate | |
247 | * substitutions to the given file name. | |
248 | */ | |
249 | buffer_init(&buffer); | |
250 | for (cp = filename; *cp; cp++) { | |
251 | if (cp[0] == '%' && cp[1] == '%') { | |
252 | buffer_append(&buffer, "%", 1); | |
253 | cp++; | |
254 | continue; | |
255 | } | |
256 | if (cp[0] == '%' && cp[1] == 'h') { | |
257 | buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir)); | |
258 | cp++; | |
259 | continue; | |
260 | } | |
261 | if (cp[0] == '%' && cp[1] == 'u') { | |
262 | buffer_append(&buffer, pw->pw_name, | |
263 | strlen(pw->pw_name)); | |
264 | cp++; | |
265 | continue; | |
266 | } | |
267 | buffer_append(&buffer, cp, 1); | |
268 | } | |
269 | buffer_append(&buffer, "\0", 1); | |
270 | ||
271 | /* | |
272 | * Ensure that filename starts anchored. If not, be backward | |
273 | * compatible and prepend the '%h/' | |
274 | */ | |
275 | file = xmalloc(MAXPATHLEN); | |
276 | cp = buffer_ptr(&buffer); | |
277 | if (*cp != '/') | |
278 | snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp); | |
279 | else | |
280 | strlcpy(file, cp, MAXPATHLEN); | |
281 | ||
282 | buffer_free(&buffer); | |
283 | return file; | |
284 | } | |
285 | ||
286 | char * | |
287 | authorized_keys_file(struct passwd *pw) | |
288 | { | |
289 | return expand_filename(options.authorized_keys_file, pw); | |
290 | } | |
291 | ||
292 | char * | |
293 | authorized_keys_file2(struct passwd *pw) | |
294 | { | |
295 | return expand_filename(options.authorized_keys_file2, pw); | |
296 | } | |
297 | ||
298 | /* | |
299 | * Check a given file for security. This is defined as all components | |
300 | * of the path to the file must either be owned by either the owner of | |
1ddf764b | 301 | * of the file or root and no directories must be group or world writable. |
c8445989 | 302 | * |
303 | * XXX Should any specific check be done for sym links ? | |
304 | * | |
305 | * Takes an open file descriptor, the file name, a uid and and | |
306 | * error buffer plus max size as arguments. | |
307 | * | |
308 | * Returns 0 on success and -1 on failure | |
309 | */ | |
310 | int | |
311 | secure_filename(FILE *f, const char *file, uid_t uid, char *err, size_t errlen) | |
312 | { | |
313 | char buf[MAXPATHLEN]; | |
314 | char *cp; | |
315 | struct stat st; | |
316 | ||
317 | if (realpath(file, buf) == NULL) { | |
318 | snprintf(err, errlen, "realpath %s failed: %s", file, | |
319 | strerror(errno)); | |
320 | return -1; | |
321 | } | |
322 | ||
323 | /* check the open file to avoid races */ | |
324 | if (fstat(fileno(f), &st) < 0 || | |
325 | (st.st_uid != 0 && st.st_uid != uid) || | |
326 | (st.st_mode & 022) != 0) { | |
327 | snprintf(err, errlen, "bad ownership or modes for file %s", | |
328 | buf); | |
329 | return -1; | |
330 | } | |
331 | ||
332 | /* for each component of the canonical path, walking upwards */ | |
333 | for (;;) { | |
334 | if ((cp = dirname(buf)) == NULL) { | |
335 | snprintf(err, errlen, "dirname() failed"); | |
336 | return -1; | |
337 | } | |
338 | strlcpy(buf, cp, sizeof(buf)); | |
339 | ||
340 | debug3("secure_filename: checking '%s'", buf); | |
341 | if (stat(buf, &st) < 0 || | |
342 | (st.st_uid != 0 && st.st_uid != uid) || | |
343 | (st.st_mode & 022) != 0) { | |
344 | snprintf(err, errlen, | |
345 | "bad ownership or modes for directory %s", buf); | |
346 | return -1; | |
347 | } | |
348 | ||
349 | /* | |
350 | * dirname should always complete with a "/" path, | |
351 | * but we can be paranoid and check for "." too | |
352 | */ | |
353 | if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) | |
354 | break; | |
355 | } | |
356 | return 0; | |
357 | } |