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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 | #include <sys/types.h> | |
29 | #include <unistd.h> | |
30 | #include <stdlib.h> | |
31 | #include <stdint.h> | |
32 | #include <string.h> | |
33 | #include <dlfcn.h> | |
34 | #include <stdio.h> | |
35 | #include <syslog.h> | |
36 | #include <errno.h> | |
37 | #include <pwd.h> | |
38 | #include <grp.h> | |
39 | #include <nss.h> | |
40 | #include "nsswitch-internal.h" | |
41 | #include "nonlocal.h" | |
42 | ||
43 | ||
44 | enum nss_status | |
45 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
46 | char *buffer, size_t buflen, int *errnop); | |
47 | enum nss_status | |
48 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
49 | char *buffer, size_t buflen, int *errnop); | |
50 | ||
51 | ||
52 | static service_user *__nss_passwd_nonlocal_database; | |
53 | ||
54 | static int | |
55 | internal_function | |
56 | __nss_passwd_nonlocal_lookup(service_user **ni, const char *fct_name, | |
57 | void **fctp) | |
58 | { | |
59 | if (__nss_passwd_nonlocal_database == NULL | |
60 | && __nss_database_lookup("passwd_nonlocal", NULL, NULL, | |
61 | &__nss_passwd_nonlocal_database) < 0) | |
62 | return -1; | |
63 | ||
64 | *ni = __nss_passwd_nonlocal_database; | |
65 | ||
66 | *fctp = __nss_lookup_function(*ni, fct_name); | |
67 | return 0; | |
68 | } | |
69 | ||
70 | ||
71 | enum nss_status | |
72 | check_nonlocal_uid(const char *user, uid_t uid, int *errnop) | |
73 | { | |
74 | enum nss_status status; | |
75 | struct passwd pwbuf; | |
76 | char *buf; | |
77 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
78 | const struct walk_nss w = { | |
79 | .lookup = &__nss_passwd_lookup, .fct_name = "getpwuid_r", | |
80 | .status = &status, .errnop = errnop, .buf = &buf, .buflen = &buflen | |
81 | }; | |
82 | const __typeof__(&_nss_nonlocal_getpwuid_r) self = &_nss_nonlocal_getpwuid_r; | |
83 | #define args (uid, &pwbuf, buf, buflen, errnop) | |
84 | #include "walk_nss.h" | |
85 | #undef args | |
86 | ||
87 | if (status == NSS_STATUS_SUCCESS) { | |
88 | syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, pwbuf.pw_name); | |
89 | free(buf); | |
90 | status = NSS_STATUS_NOTFOUND; | |
91 | } else if (status != NSS_STATUS_TRYAGAIN) { | |
92 | status = NSS_STATUS_SUCCESS; | |
93 | } | |
94 | ||
95 | return status; | |
96 | } | |
97 | ||
98 | enum nss_status | |
99 | check_nonlocal_passwd(const char *user, struct passwd *pwd, int *errnop) | |
100 | { | |
101 | enum nss_status status = NSS_STATUS_SUCCESS; | |
102 | int old_errno = errno; | |
103 | char *end; | |
104 | unsigned long uid; | |
105 | ||
106 | errno = 0; | |
107 | uid = strtoul(pwd->pw_name, &end, 10); | |
108 | if (errno == 0 && *end == '\0' && (uid_t)uid == uid) { | |
109 | errno = old_errno; | |
110 | status = check_nonlocal_uid(user, uid, errnop); | |
111 | } else { | |
112 | errno = old_errno; | |
113 | } | |
114 | if (status != NSS_STATUS_SUCCESS) | |
115 | return status; | |
116 | ||
117 | return check_nonlocal_uid(user, pwd->pw_uid, errnop); | |
118 | } | |
119 | ||
120 | enum nss_status | |
121 | check_nonlocal_user(const char *user, int *errnop) | |
122 | { | |
123 | enum nss_status status; | |
124 | struct passwd pwbuf; | |
125 | char *buf; | |
126 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
127 | const struct walk_nss w = { | |
128 | .lookup = __nss_passwd_lookup, .fct_name = "getpwnam_r", | |
129 | .status = &status, .errnop = errnop, .buf = &buf, .buflen = &buflen | |
130 | }; | |
131 | const __typeof__(&_nss_nonlocal_getpwnam_r) self = &_nss_nonlocal_getpwnam_r; | |
132 | #define args (user, &pwbuf, buf, buflen, errnop) | |
133 | #include "walk_nss.h" | |
134 | #undef args | |
135 | ||
136 | if (status == NSS_STATUS_SUCCESS) { | |
137 | free(buf); | |
138 | status = NSS_STATUS_NOTFOUND; | |
139 | } else if (status != NSS_STATUS_TRYAGAIN) { | |
140 | status = NSS_STATUS_SUCCESS; | |
141 | } | |
142 | ||
143 | return status; | |
144 | } | |
145 | ||
146 | ||
147 | static service_user *pwent_startp, *pwent_nip; | |
148 | static void *pwent_fct_start; | |
149 | static union { | |
150 | enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen, | |
151 | int *errnop); | |
152 | void *ptr; | |
153 | } pwent_fct; | |
154 | static const char *pwent_fct_name = "getpwent_r"; | |
155 | ||
156 | enum nss_status | |
157 | _nss_nonlocal_setpwent(int stayopen) | |
158 | { | |
159 | enum nss_status status; | |
160 | const struct walk_nss w = { | |
161 | .lookup = &__nss_passwd_nonlocal_lookup, .fct_name = "setpwent", | |
162 | .status = &status | |
163 | }; | |
164 | const __typeof__(&_nss_nonlocal_setpwent) self = NULL; | |
165 | #define args (stayopen) | |
166 | #include "walk_nss.h" | |
167 | #undef args | |
168 | if (status != NSS_STATUS_SUCCESS) | |
169 | return status; | |
170 | ||
171 | if (pwent_fct_start == NULL) | |
172 | __nss_passwd_nonlocal_lookup(&pwent_startp, pwent_fct_name, | |
173 | &pwent_fct_start); | |
174 | pwent_nip = pwent_startp; | |
175 | pwent_fct.ptr = pwent_fct_start; | |
176 | return NSS_STATUS_SUCCESS; | |
177 | } | |
178 | ||
179 | enum nss_status | |
180 | _nss_nonlocal_endpwent(void) | |
181 | { | |
182 | enum nss_status status; | |
183 | const struct walk_nss w = { | |
184 | .lookup = &__nss_passwd_nonlocal_lookup, .fct_name = "endpwent", | |
185 | .status = &status | |
186 | }; | |
187 | const __typeof__(&_nss_nonlocal_endpwent) self = NULL; | |
188 | ||
189 | pwent_nip = NULL; | |
190 | ||
191 | #define args () | |
192 | #include "walk_nss.h" | |
193 | #undef args | |
194 | return status; | |
195 | } | |
196 | ||
197 | enum nss_status | |
198 | _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, | |
199 | int *errnop) | |
200 | { | |
201 | enum nss_status status; | |
202 | ||
203 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
204 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
205 | return NSS_STATUS_UNAVAIL; | |
206 | ||
207 | if (pwent_nip == NULL) { | |
208 | status = _nss_nonlocal_setpwent(0); | |
209 | if (status != NSS_STATUS_SUCCESS) | |
210 | return status; | |
211 | } | |
212 | do { | |
213 | if (pwent_fct.ptr == NULL) | |
214 | status = NSS_STATUS_UNAVAIL; | |
215 | else { | |
216 | int nonlocal_errno; | |
217 | do | |
218 | status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); | |
219 | while (status == NSS_STATUS_SUCCESS && | |
220 | check_nonlocal_passwd(pwd->pw_name, pwd, &nonlocal_errno) != NSS_STATUS_SUCCESS); | |
221 | } | |
222 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
223 | return status; | |
224 | ||
225 | if (status == NSS_STATUS_SUCCESS) | |
226 | return NSS_STATUS_SUCCESS; | |
227 | } while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0); | |
228 | ||
229 | pwent_nip = NULL; | |
230 | return NSS_STATUS_NOTFOUND; | |
231 | } | |
232 | ||
233 | ||
234 | enum nss_status | |
235 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
236 | char *buffer, size_t buflen, int *errnop) | |
237 | { | |
238 | enum nss_status status; | |
239 | int group_errno; | |
240 | const struct walk_nss w = { | |
241 | .lookup = __nss_passwd_nonlocal_lookup, .fct_name = "getpwnam_r", | |
242 | .status = &status, .errnop = errnop | |
243 | }; | |
244 | const __typeof__(&_nss_nonlocal_getpwnam_r) self = NULL; | |
245 | ||
246 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
247 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
248 | return NSS_STATUS_UNAVAIL; | |
249 | ||
250 | #define args (name, pwd, buffer, buflen, errnop) | |
251 | #include "walk_nss.h" | |
252 | #undef args | |
253 | if (status != NSS_STATUS_SUCCESS) | |
254 | return status; | |
255 | ||
256 | if (strcmp(name, pwd->pw_name) != 0) { | |
257 | syslog(LOG_ERR, "nss_nonlocal: discarding user %s from lookup for user %s\n", pwd->pw_name, name); | |
258 | return NSS_STATUS_NOTFOUND; | |
259 | } | |
260 | ||
261 | status = check_nonlocal_passwd(name, pwd, errnop); | |
262 | if (status != NSS_STATUS_SUCCESS) | |
263 | return status; | |
264 | ||
265 | if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) != | |
266 | NSS_STATUS_SUCCESS) | |
267 | pwd->pw_gid = 65534 /* nogroup */; | |
268 | return NSS_STATUS_SUCCESS; | |
269 | } | |
270 | ||
271 | enum nss_status | |
272 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
273 | char *buffer, size_t buflen, int *errnop) | |
274 | { | |
275 | enum nss_status status; | |
276 | int group_errno; | |
277 | const struct walk_nss w = { | |
278 | .lookup = &__nss_passwd_nonlocal_lookup, .fct_name = "getpwuid_r", | |
279 | .status = &status, .errnop = errnop | |
280 | }; | |
281 | const __typeof__(&_nss_nonlocal_getpwuid_r) self = NULL; | |
282 | ||
283 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
284 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
285 | return NSS_STATUS_UNAVAIL; | |
286 | ||
287 | #define args (uid, pwd, buffer, buflen, errnop) | |
288 | #include "walk_nss.h" | |
289 | #undef args | |
290 | if (status != NSS_STATUS_SUCCESS) | |
291 | return status; | |
292 | ||
293 | if (uid != pwd->pw_uid) { | |
294 | syslog(LOG_ERR, "nss_nonlocal: discarding uid %d from lookup for uid %d\n", pwd->pw_uid, uid); | |
295 | return NSS_STATUS_NOTFOUND; | |
296 | } | |
297 | ||
298 | status = check_nonlocal_passwd(pwd->pw_name, pwd, errnop); | |
299 | if (status != NSS_STATUS_SUCCESS) | |
300 | return status; | |
301 | ||
302 | if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) != | |
303 | NSS_STATUS_SUCCESS) | |
304 | pwd->pw_gid = 65534 /* nogroup */; | |
305 | return NSS_STATUS_SUCCESS; | |
306 | } |