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f6903667 AK |
1 | /* |
2 | * nonlocal-passwd.c | |
3 | * passwd database for nss_nonlocal proxy. | |
4 | * | |
96a1ee0f AK |
5 | * Copyright © 2007–2010 Anders Kaseorg <andersk@mit.edu> and Tim |
6 | * Abbott <tabbott@mit.edu> | |
f6903667 | 7 | * |
96a1ee0f | 8 | * This file is part of nss_nonlocal. |
f6903667 | 9 | * |
96a1ee0f AK |
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. | |
f6903667 | 14 | * |
96a1ee0f AK |
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 | |
f6903667 AK |
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 | ||
c1812233 AK |
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); | |
f7293a54 | 50 | |
f6903667 | 51 | |
cbb0e3ea AK |
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) | |
f6903667 | 58 | { |
cbb0e3ea AK |
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; | |
f6903667 | 65 | |
cbb0e3ea AK |
66 | *fctp = __nss_lookup_function(*ni, fct_name); |
67 | return 0; | |
f6903667 AK |
68 | } |
69 | ||
70 | ||
f6903667 AK |
71 | enum nss_status |
72 | check_nonlocal_uid(const char *user, uid_t uid, int *errnop) | |
73 | { | |
30fb3957 | 74 | enum nss_status status; |
f7293a54 | 75 | struct passwd pwbuf; |
cbb0e3ea | 76 | char *buf; |
8870ee9c | 77 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); |
cbb0e3ea AK |
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 | |
30fb3957 AK |
86 | |
87 | if (status == NSS_STATUS_SUCCESS) { | |
f7293a54 | 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); |
cbb0e3ea | 89 | free(buf); |
f6903667 | 90 | status = NSS_STATUS_NOTFOUND; |
30fb3957 AK |
91 | } else if (status != NSS_STATUS_TRYAGAIN) { |
92 | status = NSS_STATUS_SUCCESS; | |
f6903667 | 93 | } |
30fb3957 | 94 | |
f6903667 AK |
95 | return status; |
96 | } | |
97 | ||
cf338316 AK |
98 | enum nss_status |
99 | check_nonlocal_passwd(const char *user, struct passwd *pwd, int *errnop) | |
100 | { | |
a07a7616 AK |
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); | |
f4061d47 AK |
108 | if (errno == 0 && *end == '\0' && (uid_t)uid == uid) { |
109 | errno = old_errno; | |
a07a7616 | 110 | status = check_nonlocal_uid(user, uid, errnop); |
f4061d47 AK |
111 | } else { |
112 | errno = old_errno; | |
113 | } | |
a07a7616 AK |
114 | if (status != NSS_STATUS_SUCCESS) |
115 | return status; | |
116 | ||
cf338316 AK |
117 | return check_nonlocal_uid(user, pwd->pw_uid, errnop); |
118 | } | |
119 | ||
48479fc7 TA |
120 | enum nss_status |
121 | check_nonlocal_user(const char *user, int *errnop) | |
122 | { | |
30fb3957 | 123 | enum nss_status status; |
48479fc7 | 124 | struct passwd pwbuf; |
cbb0e3ea | 125 | char *buf; |
8870ee9c | 126 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); |
cbb0e3ea AK |
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 | |
30fb3957 | 135 | |
cbb0e3ea | 136 | if (status == NSS_STATUS_SUCCESS) { |
30fb3957 | 137 | free(buf); |
30fb3957 | 138 | status = NSS_STATUS_NOTFOUND; |
cbb0e3ea | 139 | } else if (status != NSS_STATUS_TRYAGAIN) { |
30fb3957 | 140 | status = NSS_STATUS_SUCCESS; |
cbb0e3ea | 141 | } |
30fb3957 | 142 | |
48479fc7 TA |
143 | return status; |
144 | } | |
f6903667 | 145 | |
775f7dc3 AK |
146 | enum nss_status |
147 | get_nonlocal_passwd(const char *name, struct passwd *pwd, char **buffer, | |
148 | int *errnop) | |
149 | { | |
150 | enum nss_status status; | |
151 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
152 | const struct walk_nss w = { | |
153 | .lookup = __nss_passwd_nonlocal_lookup, .fct_name = "getpwnam_r", | |
154 | .status = &status, .errnop = errnop, .buf = buffer, .buflen = &buflen | |
155 | }; | |
156 | const __typeof__(&_nss_nonlocal_getpwnam_r) self = NULL; | |
157 | #define args (name, pwd, *buffer, buflen, errnop) | |
158 | #include "walk_nss.h" | |
159 | #undef args | |
160 | return status; | |
161 | } | |
162 | ||
1e78305d | 163 | |
cbb0e3ea | 164 | static service_user *pwent_startp, *pwent_nip; |
f6903667 AK |
165 | static void *pwent_fct_start; |
166 | static union { | |
167 | enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen, | |
168 | int *errnop); | |
169 | void *ptr; | |
170 | } pwent_fct; | |
171 | static const char *pwent_fct_name = "getpwent_r"; | |
172 | ||
173 | enum nss_status | |
174 | _nss_nonlocal_setpwent(int stayopen) | |
175 | { | |
f6903667 | 176 | enum nss_status status; |
cbb0e3ea AK |
177 | const struct walk_nss w = { |
178 | .lookup = &__nss_passwd_nonlocal_lookup, .fct_name = "setpwent", | |
179 | .status = &status | |
180 | }; | |
181 | const __typeof__(&_nss_nonlocal_setpwent) self = NULL; | |
182 | #define args (stayopen) | |
183 | #include "walk_nss.h" | |
184 | #undef args | |
f6903667 AK |
185 | if (status != NSS_STATUS_SUCCESS) |
186 | return status; | |
187 | ||
f6903667 | 188 | if (pwent_fct_start == NULL) |
cbb0e3ea AK |
189 | __nss_passwd_nonlocal_lookup(&pwent_startp, pwent_fct_name, |
190 | &pwent_fct_start); | |
191 | pwent_nip = pwent_startp; | |
f6903667 AK |
192 | pwent_fct.ptr = pwent_fct_start; |
193 | return NSS_STATUS_SUCCESS; | |
194 | } | |
195 | ||
196 | enum nss_status | |
197 | _nss_nonlocal_endpwent(void) | |
198 | { | |
f6903667 | 199 | enum nss_status status; |
cbb0e3ea AK |
200 | const struct walk_nss w = { |
201 | .lookup = &__nss_passwd_nonlocal_lookup, .fct_name = "endpwent", | |
202 | .status = &status | |
203 | }; | |
204 | const __typeof__(&_nss_nonlocal_endpwent) self = NULL; | |
f6903667 AK |
205 | |
206 | pwent_nip = NULL; | |
207 | ||
cbb0e3ea AK |
208 | #define args () |
209 | #include "walk_nss.h" | |
210 | #undef args | |
f6903667 AK |
211 | return status; |
212 | } | |
213 | ||
214 | enum nss_status | |
215 | _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, | |
216 | int *errnop) | |
217 | { | |
218 | enum nss_status status; | |
a360549e TA |
219 | |
220 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
c1812233 | 221 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
a360549e TA |
222 | return NSS_STATUS_UNAVAIL; |
223 | ||
f6903667 AK |
224 | if (pwent_nip == NULL) { |
225 | status = _nss_nonlocal_setpwent(0); | |
226 | if (status != NSS_STATUS_SUCCESS) | |
227 | return status; | |
228 | } | |
229 | do { | |
230 | if (pwent_fct.ptr == NULL) | |
231 | status = NSS_STATUS_UNAVAIL; | |
232 | else { | |
233 | int nonlocal_errno; | |
234 | do | |
a360549e | 235 | status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); |
f6903667 | 236 | while (status == NSS_STATUS_SUCCESS && |
cf338316 | 237 | check_nonlocal_passwd(pwd->pw_name, pwd, &nonlocal_errno) != NSS_STATUS_SUCCESS); |
f6903667 AK |
238 | } |
239 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
240 | return status; | |
241 | ||
242 | if (status == NSS_STATUS_SUCCESS) | |
243 | return NSS_STATUS_SUCCESS; | |
244 | } while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0); | |
245 | ||
246 | pwent_nip = NULL; | |
247 | return NSS_STATUS_NOTFOUND; | |
248 | } | |
249 | ||
250 | ||
251 | enum nss_status | |
252 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
253 | char *buffer, size_t buflen, int *errnop) | |
254 | { | |
f6903667 | 255 | enum nss_status status; |
f6903667 | 256 | int group_errno; |
cbb0e3ea AK |
257 | const struct walk_nss w = { |
258 | .lookup = __nss_passwd_nonlocal_lookup, .fct_name = "getpwnam_r", | |
259 | .status = &status, .errnop = errnop | |
260 | }; | |
261 | const __typeof__(&_nss_nonlocal_getpwnam_r) self = NULL; | |
f6903667 | 262 | |
a360549e | 263 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 264 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
48479fc7 TA |
265 | return NSS_STATUS_UNAVAIL; |
266 | ||
cbb0e3ea AK |
267 | #define args (name, pwd, buffer, buflen, errnop) |
268 | #include "walk_nss.h" | |
269 | #undef args | |
f6903667 AK |
270 | if (status != NSS_STATUS_SUCCESS) |
271 | return status; | |
272 | ||
22562df0 AK |
273 | if (strcmp(name, pwd->pw_name) != 0) { |
274 | syslog(LOG_ERR, "nss_nonlocal: discarding user %s from lookup for user %s\n", pwd->pw_name, name); | |
275 | return NSS_STATUS_NOTFOUND; | |
276 | } | |
277 | ||
cf338316 | 278 | status = check_nonlocal_passwd(name, pwd, errnop); |
f6903667 AK |
279 | if (status != NSS_STATUS_SUCCESS) |
280 | return status; | |
281 | ||
25468b96 | 282 | if (check_nonlocal_gid(name, NULL, pwd->pw_gid, &group_errno) != |
f6903667 AK |
283 | NSS_STATUS_SUCCESS) |
284 | pwd->pw_gid = 65534 /* nogroup */; | |
285 | return NSS_STATUS_SUCCESS; | |
286 | } | |
287 | ||
288 | enum nss_status | |
289 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
290 | char *buffer, size_t buflen, int *errnop) | |
291 | { | |
f6903667 | 292 | enum nss_status status; |
f6903667 | 293 | int group_errno; |
cbb0e3ea AK |
294 | const struct walk_nss w = { |
295 | .lookup = &__nss_passwd_nonlocal_lookup, .fct_name = "getpwuid_r", | |
296 | .status = &status, .errnop = errnop | |
297 | }; | |
298 | const __typeof__(&_nss_nonlocal_getpwuid_r) self = NULL; | |
f6903667 | 299 | |
a360549e | 300 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 301 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
f6903667 AK |
302 | return NSS_STATUS_UNAVAIL; |
303 | ||
cbb0e3ea AK |
304 | #define args (uid, pwd, buffer, buflen, errnop) |
305 | #include "walk_nss.h" | |
306 | #undef args | |
f6903667 AK |
307 | if (status != NSS_STATUS_SUCCESS) |
308 | return status; | |
309 | ||
8027fdc4 AK |
310 | if (uid != pwd->pw_uid) { |
311 | syslog(LOG_ERR, "nss_nonlocal: discarding uid %d from lookup for uid %d\n", pwd->pw_uid, uid); | |
312 | return NSS_STATUS_NOTFOUND; | |
313 | } | |
314 | ||
cf338316 | 315 | status = check_nonlocal_passwd(pwd->pw_name, pwd, errnop); |
f6903667 AK |
316 | if (status != NSS_STATUS_SUCCESS) |
317 | return status; | |
318 | ||
25468b96 | 319 | if (check_nonlocal_gid(pwd->pw_name, NULL, pwd->pw_gid, &group_errno) != |
f6903667 AK |
320 | NSS_STATUS_SUCCESS) |
321 | pwd->pw_gid = 65534 /* nogroup */; | |
322 | return NSS_STATUS_SUCCESS; | |
323 | } |