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1 | /* | |
2 | * nonlocal-passwd.c | |
3 | * passwd database for nss_nonlocal proxy. | |
4 | * | |
5 | * Copyright © 2007–2010 Anders Kaseorg <andersk@mit.edu> and Tim | |
6 | * Abbott <tabbott@mit.edu> | |
7 | * | |
8 | * This file is part of nss_nonlocal. | |
9 | * | |
10 | * nss_nonlocal is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU Lesser General Public License | |
12 | * as published by the Free Software Foundation; either version 2.1 of | |
13 | * the License, or (at your option) any later version. | |
14 | * | |
15 | * nss_nonlocal is distributed in the hope that it will be useful, but | |
16 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | * Lesser General Public License for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU Lesser General Public | |
21 | * License along with nss_nonlocal; if not, write to the Free Software | |
22 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | |
23 | * 02110-1301 USA | |
24 | */ | |
25 | ||
26 | ||
27 | #define _GNU_SOURCE | |
28 | ||
29 | #include <sys/types.h> | |
30 | #include <dlfcn.h> | |
31 | #include <errno.h> | |
32 | #include <nss.h> | |
33 | #include <pwd.h> | |
34 | #include <stdbool.h> | |
35 | #include <stddef.h> | |
36 | #include <stdlib.h> | |
37 | #include <string.h> | |
38 | #include <syslog.h> | |
39 | #include <unistd.h> | |
40 | ||
41 | #include "nsswitch-internal.h" | |
42 | #include "nonlocal.h" | |
43 | ||
44 | ||
45 | enum nss_status | |
46 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
47 | char *buffer, size_t buflen, int *errnop); | |
48 | enum nss_status | |
49 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
50 | char *buffer, size_t buflen, int *errnop); | |
51 | ||
52 | ||
53 | static service_user *__nss_passwd_nonlocal_database; | |
54 | ||
55 | static int | |
56 | internal_function | |
57 | __nss_passwd_nonlocal_lookup2(service_user **ni, const char *fct_name, | |
58 | const char *fct2_name, void **fctp) | |
59 | { | |
60 | if (__nss_passwd_nonlocal_database == NULL | |
61 | && __nss_database_lookup("passwd_nonlocal", NULL, NULL, | |
62 | &__nss_passwd_nonlocal_database) < 0) | |
63 | return -1; | |
64 | ||
65 | *ni = __nss_passwd_nonlocal_database; | |
66 | ||
67 | *fctp = __nss_lookup_function(*ni, fct_name); | |
68 | if (*fctp == NULL && fct2_name != NULL) | |
69 | *fctp = __nss_lookup_function(*ni, fct2_name); | |
70 | return 0; | |
71 | } | |
72 | ||
73 | ||
74 | enum nss_status | |
75 | check_nonlocal_uid(const char *user, uid_t uid, int *errnop) | |
76 | { | |
77 | enum nss_status status; | |
78 | struct passwd pwbuf; | |
79 | char *buf; | |
80 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
81 | const struct walk_nss w = { | |
82 | .lookup2 = &__nss_passwd_lookup2, .fct_name = "getpwuid_r", | |
83 | .status = &status, .errnop = errnop, .buf = &buf, .buflen = &buflen | |
84 | }; | |
85 | const __typeof__(&_nss_nonlocal_getpwuid_r) self = &_nss_nonlocal_getpwuid_r; | |
86 | #define args (uid, &pwbuf, buf, buflen, errnop) | |
87 | #include "walk_nss.h" | |
88 | #undef args | |
89 | ||
90 | if (status == NSS_STATUS_SUCCESS) { | |
91 | syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, pwbuf.pw_name); | |
92 | free(buf); | |
93 | status = NSS_STATUS_NOTFOUND; | |
94 | } else if (status != NSS_STATUS_TRYAGAIN) { | |
95 | status = NSS_STATUS_SUCCESS; | |
96 | } | |
97 | ||
98 | return status; | |
99 | } | |
100 | ||
101 | enum nss_status | |
102 | check_nonlocal_passwd(const char *user, struct passwd *pwd, int *errnop) | |
103 | { | |
104 | enum nss_status status = NSS_STATUS_SUCCESS; | |
105 | int old_errno = errno; | |
106 | char *end; | |
107 | unsigned long uid; | |
108 | ||
109 | errno = 0; | |
110 | uid = strtoul(pwd->pw_name, &end, 10); | |
111 | if (errno == 0 && *end == '\0' && (uid_t)uid == uid) { | |
112 | errno = old_errno; | |
113 | status = check_nonlocal_uid(user, uid, errnop); | |
114 | } else { | |
115 | errno = old_errno; | |
116 | } | |
117 | if (status != NSS_STATUS_SUCCESS) | |
118 | return status; | |
119 | ||
120 | return check_nonlocal_uid(user, pwd->pw_uid, errnop); | |
121 | } | |
122 | ||
123 | enum nss_status | |
124 | check_nonlocal_user(const char *user, int *errnop) | |
125 | { | |
126 | enum nss_status status; | |
127 | struct passwd pwbuf; | |
128 | char *buf; | |
129 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
130 | const struct walk_nss w = { | |
131 | .lookup2 = __nss_passwd_lookup2, .fct_name = "getpwnam_r", | |
132 | .status = &status, .errnop = errnop, .buf = &buf, .buflen = &buflen | |
133 | }; | |
134 | const __typeof__(&_nss_nonlocal_getpwnam_r) self = &_nss_nonlocal_getpwnam_r; | |
135 | #define args (user, &pwbuf, buf, buflen, errnop) | |
136 | #include "walk_nss.h" | |
137 | #undef args | |
138 | ||
139 | if (status == NSS_STATUS_SUCCESS) { | |
140 | free(buf); | |
141 | status = NSS_STATUS_NOTFOUND; | |
142 | } else if (status != NSS_STATUS_TRYAGAIN) { | |
143 | status = NSS_STATUS_SUCCESS; | |
144 | } | |
145 | ||
146 | return status; | |
147 | } | |
148 | ||
149 | enum nss_status | |
150 | get_nonlocal_passwd(const char *name, struct passwd *pwd, char **buffer, | |
151 | int *errnop) | |
152 | { | |
153 | enum nss_status status; | |
154 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
155 | const struct walk_nss w = { | |
156 | .lookup2 = __nss_passwd_nonlocal_lookup2, .fct_name = "getpwnam_r", | |
157 | .status = &status, .errnop = errnop, .buf = buffer, .buflen = &buflen | |
158 | }; | |
159 | const __typeof__(&_nss_nonlocal_getpwnam_r) self = NULL; | |
160 | #define args (name, pwd, *buffer, buflen, errnop) | |
161 | #include "walk_nss.h" | |
162 | #undef args | |
163 | return status; | |
164 | } | |
165 | ||
166 | ||
167 | static bool pwent_initialized = false; | |
168 | static service_user *pwent_startp, *pwent_nip; | |
169 | static void *pwent_fct_start; | |
170 | static union { | |
171 | enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen, | |
172 | int *errnop); | |
173 | void *ptr; | |
174 | } pwent_fct; | |
175 | static const char *pwent_fct_name = "getpwent_r"; | |
176 | ||
177 | enum nss_status | |
178 | _nss_nonlocal_setpwent(int stayopen) | |
179 | { | |
180 | enum nss_status status; | |
181 | const struct walk_nss w = { | |
182 | .lookup2 = &__nss_passwd_nonlocal_lookup2, .fct_name = "setpwent", | |
183 | .status = &status | |
184 | }; | |
185 | const __typeof__(&_nss_nonlocal_setpwent) self = NULL; | |
186 | #define args (stayopen) | |
187 | #include "walk_nss.h" | |
188 | #undef args | |
189 | if (status != NSS_STATUS_SUCCESS) | |
190 | return status; | |
191 | ||
192 | if (!pwent_initialized) { | |
193 | __nss_passwd_nonlocal_lookup2(&pwent_startp, pwent_fct_name, NULL, | |
194 | &pwent_fct_start); | |
195 | __sync_synchronize(); | |
196 | pwent_initialized = true; | |
197 | } | |
198 | pwent_nip = pwent_startp; | |
199 | pwent_fct.ptr = pwent_fct_start; | |
200 | return NSS_STATUS_SUCCESS; | |
201 | } | |
202 | ||
203 | enum nss_status | |
204 | _nss_nonlocal_endpwent(void) | |
205 | { | |
206 | enum nss_status status; | |
207 | const struct walk_nss w = { | |
208 | .lookup2 = &__nss_passwd_nonlocal_lookup2, .fct_name = "endpwent", | |
209 | .status = &status, .all_values = 1, | |
210 | }; | |
211 | const __typeof__(&_nss_nonlocal_endpwent) self = NULL; | |
212 | ||
213 | pwent_nip = NULL; | |
214 | ||
215 | #define args () | |
216 | #include "walk_nss.h" | |
217 | #undef args | |
218 | return status; | |
219 | } | |
220 | ||
221 | enum nss_status | |
222 | _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, | |
223 | int *errnop) | |
224 | { | |
225 | enum nss_status status; | |
226 | ||
227 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
228 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
229 | return NSS_STATUS_UNAVAIL; | |
230 | ||
231 | if (pwent_nip == NULL) { | |
232 | status = _nss_nonlocal_setpwent(0); | |
233 | if (status != NSS_STATUS_SUCCESS) | |
234 | return status; | |
235 | } | |
236 | do { | |
237 | if (pwent_fct.ptr == NULL) | |
238 | status = NSS_STATUS_UNAVAIL; | |
239 | else { | |
240 | int nonlocal_errno; | |
241 | do | |
242 | status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); | |
243 | while (status == NSS_STATUS_SUCCESS && | |
244 | check_nonlocal_passwd(pwd->pw_name, pwd, &nonlocal_errno) != NSS_STATUS_SUCCESS); | |
245 | } | |
246 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
247 | return status; | |
248 | ||
249 | if (status == NSS_STATUS_SUCCESS) | |
250 | return NSS_STATUS_SUCCESS; | |
251 | } while (__nss_next2(&pwent_nip, pwent_fct_name, 0, &pwent_fct.ptr, status, | |
252 | 0) == 0); | |
253 | ||
254 | pwent_nip = NULL; | |
255 | return NSS_STATUS_NOTFOUND; | |
256 | } | |
257 | ||
258 | ||
259 | enum nss_status | |
260 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
261 | char *buffer, size_t buflen, int *errnop) | |
262 | { | |
263 | enum nss_status status; | |
264 | int group_errno; | |
265 | const struct walk_nss w = { | |
266 | .lookup2 = __nss_passwd_nonlocal_lookup2, .fct_name = "getpwnam_r", | |
267 | .status = &status, .errnop = errnop | |
268 | }; | |
269 | const __typeof__(&_nss_nonlocal_getpwnam_r) self = NULL; | |
270 | ||
271 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
272 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
273 | return NSS_STATUS_UNAVAIL; | |
274 | ||
275 | #define args (name, pwd, buffer, buflen, errnop) | |
276 | #include "walk_nss.h" | |
277 | #undef args | |
278 | if (status != NSS_STATUS_SUCCESS) | |
279 | return status; | |
280 | ||
281 | if (strcmp(name, pwd->pw_name) != 0) { | |
282 | syslog(LOG_ERR, "nss_nonlocal: discarding user %s from lookup for user %s\n", pwd->pw_name, name); | |
283 | return NSS_STATUS_NOTFOUND; | |
284 | } | |
285 | ||
286 | status = check_nonlocal_passwd(name, pwd, errnop); | |
287 | if (status != NSS_STATUS_SUCCESS) | |
288 | return status; | |
289 | ||
290 | if (check_nonlocal_gid(name, NULL, pwd->pw_gid, &group_errno) != | |
291 | NSS_STATUS_SUCCESS) | |
292 | pwd->pw_gid = 65534 /* nogroup */; | |
293 | return NSS_STATUS_SUCCESS; | |
294 | } | |
295 | ||
296 | enum nss_status | |
297 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
298 | char *buffer, size_t buflen, int *errnop) | |
299 | { | |
300 | enum nss_status status; | |
301 | int group_errno; | |
302 | const struct walk_nss w = { | |
303 | .lookup2 = &__nss_passwd_nonlocal_lookup2, .fct_name = "getpwuid_r", | |
304 | .status = &status, .errnop = errnop | |
305 | }; | |
306 | const __typeof__(&_nss_nonlocal_getpwuid_r) self = NULL; | |
307 | ||
308 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
309 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
310 | return NSS_STATUS_UNAVAIL; | |
311 | ||
312 | #define args (uid, pwd, buffer, buflen, errnop) | |
313 | #include "walk_nss.h" | |
314 | #undef args | |
315 | if (status != NSS_STATUS_SUCCESS) | |
316 | return status; | |
317 | ||
318 | if (uid != pwd->pw_uid) { | |
319 | syslog(LOG_ERR, "nss_nonlocal: discarding uid %d from lookup for uid %d\n", pwd->pw_uid, uid); | |
320 | return NSS_STATUS_NOTFOUND; | |
321 | } | |
322 | ||
323 | status = check_nonlocal_passwd(pwd->pw_name, pwd, errnop); | |
324 | if (status != NSS_STATUS_SUCCESS) | |
325 | return status; | |
326 | ||
327 | if (check_nonlocal_gid(pwd->pw_name, NULL, pwd->pw_gid, &group_errno) != | |
328 | NSS_STATUS_SUCCESS) | |
329 | pwd->pw_gid = 65534 /* nogroup */; | |
330 | return NSS_STATUS_SUCCESS; | |
331 | } |