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1 | /* | |
2 | * nonlocal-passwd.c | |
3 | * passwd database for nss_nonlocal proxy. | |
4 | * | |
5 | * Copyright © 2007 Anders Kaseorg <andersk@mit.edu> and Tim Abbott | |
6 | * <tabbott@mit.edu> | |
7 | * | |
8 | * Permission is hereby granted, free of charge, to any person | |
9 | * obtaining a copy of this software and associated documentation | |
10 | * files (the "Software"), to deal in the Software without | |
11 | * restriction, including without limitation the rights to use, copy, | |
12 | * modify, merge, publish, distribute, sublicense, and/or sell copies | |
13 | * of the Software, and to permit persons to whom the Software is | |
14 | * furnished to do so, subject to the following conditions: | |
15 | * | |
16 | * The above copyright notice and this permission notice shall be | |
17 | * included in all copies or substantial portions of the Software. | |
18 | * | |
19 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
20 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |
21 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
22 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS | |
23 | * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN | |
24 | * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |
25 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
26 | * SOFTWARE. | |
27 | */ | |
28 | ||
29 | ||
30 | #define _GNU_SOURCE | |
31 | #include <sys/types.h> | |
32 | #include <unistd.h> | |
33 | #include <stdlib.h> | |
34 | #include <stdint.h> | |
35 | #include <string.h> | |
36 | #include <dlfcn.h> | |
37 | #include <stdio.h> | |
38 | #include <syslog.h> | |
39 | #include <errno.h> | |
40 | #include <pwd.h> | |
41 | #include <grp.h> | |
42 | #include <nss.h> | |
43 | #include "nsswitch-internal.h" | |
44 | #include "nonlocal.h" | |
45 | ||
46 | ||
47 | enum nss_status | |
48 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
49 | char *buffer, size_t buflen, int *errnop); | |
50 | enum nss_status | |
51 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
52 | char *buffer, size_t buflen, int *errnop); | |
53 | ||
54 | ||
55 | static service_user * | |
56 | nss_passwd_nonlocal_database(void) | |
57 | { | |
58 | static service_user *nip = NULL; | |
59 | if (nip == NULL) | |
60 | __nss_database_lookup("passwd_nonlocal", NULL, "", &nip); | |
61 | ||
62 | return nip; | |
63 | } | |
64 | ||
65 | ||
66 | enum nss_status | |
67 | check_nonlocal_uid(const char *user, uid_t uid, int *errnop) | |
68 | { | |
69 | static const char *fct_name = "getpwuid_r"; | |
70 | static service_user *startp = NULL; | |
71 | static void *fct_start = NULL; | |
72 | enum nss_status status; | |
73 | service_user *nip; | |
74 | union { | |
75 | enum nss_status (*l)(uid_t uid, struct passwd *pwd, | |
76 | char *buffer, size_t buflen, int *errnop); | |
77 | void *ptr; | |
78 | } fct; | |
79 | struct passwd pwbuf; | |
80 | int old_errno = errno; | |
81 | ||
82 | int buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
83 | char *buf = malloc(buflen); | |
84 | if (buf == NULL) { | |
85 | *errnop = ENOMEM; | |
86 | errno = old_errno; | |
87 | return NSS_STATUS_TRYAGAIN; | |
88 | } | |
89 | ||
90 | if (fct_start == NULL && | |
91 | __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { | |
92 | free(buf); | |
93 | return NSS_STATUS_UNAVAIL; | |
94 | } | |
95 | nip = startp; | |
96 | fct.ptr = fct_start; | |
97 | do { | |
98 | if (fct.l == _nss_nonlocal_getpwuid_r) | |
99 | status = NSS_STATUS_NOTFOUND; | |
100 | else | |
101 | status = DL_CALL_FCT(fct.l, (uid, &pwbuf, buf, buflen, errnop)); | |
102 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
103 | break; | |
104 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
105 | ||
106 | if (status == NSS_STATUS_SUCCESS) { | |
107 | syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, pwbuf.pw_name); | |
108 | status = NSS_STATUS_NOTFOUND; | |
109 | } else if (status != NSS_STATUS_TRYAGAIN) { | |
110 | status = NSS_STATUS_SUCCESS; | |
111 | } | |
112 | ||
113 | free(buf); | |
114 | return status; | |
115 | } | |
116 | ||
117 | enum nss_status | |
118 | check_nonlocal_user(const char *user, int *errnop) | |
119 | { | |
120 | static const char *fct_name = "getpwnam_r"; | |
121 | static service_user *startp = NULL; | |
122 | static void *fct_start = NULL; | |
123 | enum nss_status status; | |
124 | service_user *nip; | |
125 | union { | |
126 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
127 | char *buffer, size_t buflen, int *errnop); | |
128 | void *ptr; | |
129 | } fct; | |
130 | struct passwd pwbuf; | |
131 | int old_errno = errno; | |
132 | ||
133 | int buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
134 | char *buf = malloc(buflen); | |
135 | if (buf == NULL) { | |
136 | *errnop = ENOMEM; | |
137 | errno = old_errno; | |
138 | return NSS_STATUS_TRYAGAIN; | |
139 | } | |
140 | ||
141 | if (fct_start == NULL && | |
142 | __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { | |
143 | free(buf); | |
144 | return NSS_STATUS_UNAVAIL; | |
145 | } | |
146 | nip = startp; | |
147 | fct.ptr = fct_start; | |
148 | do { | |
149 | if (fct.l == _nss_nonlocal_getpwnam_r) | |
150 | status = NSS_STATUS_NOTFOUND; | |
151 | else | |
152 | status = DL_CALL_FCT(fct.l, (user, &pwbuf, buf, buflen, errnop)); | |
153 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
154 | break; | |
155 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
156 | ||
157 | if (status == NSS_STATUS_SUCCESS) | |
158 | status = NSS_STATUS_NOTFOUND; | |
159 | else if (status != NSS_STATUS_TRYAGAIN) | |
160 | status = NSS_STATUS_SUCCESS; | |
161 | ||
162 | free(buf); | |
163 | return status; | |
164 | } | |
165 | ||
166 | ||
167 | static service_user *pwent_nip = NULL; | |
168 | static void *pwent_fct_start; | |
169 | static union { | |
170 | enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen, | |
171 | int *errnop); | |
172 | void *ptr; | |
173 | } pwent_fct; | |
174 | static const char *pwent_fct_name = "getpwent_r"; | |
175 | ||
176 | enum nss_status | |
177 | _nss_nonlocal_setpwent(int stayopen) | |
178 | { | |
179 | static const char *fct_name = "setpwent"; | |
180 | static void *fct_start = NULL; | |
181 | enum nss_status status; | |
182 | service_user *nip; | |
183 | union { | |
184 | enum nss_status (*l)(int stayopen); | |
185 | void *ptr; | |
186 | } fct; | |
187 | ||
188 | nip = nss_passwd_nonlocal_database(); | |
189 | if (nip == NULL) | |
190 | return NSS_STATUS_UNAVAIL; | |
191 | if (fct_start == NULL) | |
192 | fct_start = __nss_lookup_function(nip, fct_name); | |
193 | fct.ptr = fct_start; | |
194 | do { | |
195 | if (fct.ptr == NULL) | |
196 | status = NSS_STATUS_UNAVAIL; | |
197 | else | |
198 | status = DL_CALL_FCT(fct.l, (stayopen)); | |
199 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
200 | if (status != NSS_STATUS_SUCCESS) | |
201 | return status; | |
202 | ||
203 | pwent_nip = nip; | |
204 | if (pwent_fct_start == NULL) | |
205 | pwent_fct_start = __nss_lookup_function(nip, pwent_fct_name); | |
206 | pwent_fct.ptr = pwent_fct_start; | |
207 | return NSS_STATUS_SUCCESS; | |
208 | } | |
209 | ||
210 | enum nss_status | |
211 | _nss_nonlocal_endpwent(void) | |
212 | { | |
213 | static const char *fct_name = "endpwent"; | |
214 | static void *fct_start = NULL; | |
215 | enum nss_status status; | |
216 | service_user *nip; | |
217 | union { | |
218 | enum nss_status (*l)(void); | |
219 | void *ptr; | |
220 | } fct; | |
221 | ||
222 | pwent_nip = NULL; | |
223 | ||
224 | nip = nss_passwd_nonlocal_database(); | |
225 | if (nip == NULL) | |
226 | return NSS_STATUS_UNAVAIL; | |
227 | if (fct_start == NULL) | |
228 | fct_start = __nss_lookup_function(nip, fct_name); | |
229 | fct.ptr = fct_start; | |
230 | do { | |
231 | if (fct.ptr == NULL) | |
232 | status = NSS_STATUS_UNAVAIL; | |
233 | else | |
234 | status = DL_CALL_FCT(fct.l, ()); | |
235 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
236 | return status; | |
237 | } | |
238 | ||
239 | enum nss_status | |
240 | _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, | |
241 | int *errnop) | |
242 | { | |
243 | enum nss_status status; | |
244 | ||
245 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
246 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
247 | return NSS_STATUS_UNAVAIL; | |
248 | ||
249 | if (pwent_nip == NULL) { | |
250 | status = _nss_nonlocal_setpwent(0); | |
251 | if (status != NSS_STATUS_SUCCESS) | |
252 | return status; | |
253 | } | |
254 | do { | |
255 | if (pwent_fct.ptr == NULL) | |
256 | status = NSS_STATUS_UNAVAIL; | |
257 | else { | |
258 | int nonlocal_errno; | |
259 | do | |
260 | status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); | |
261 | while (status == NSS_STATUS_SUCCESS && | |
262 | check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, &nonlocal_errno) != NSS_STATUS_SUCCESS); | |
263 | } | |
264 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
265 | return status; | |
266 | ||
267 | if (status == NSS_STATUS_SUCCESS) | |
268 | return NSS_STATUS_SUCCESS; | |
269 | } while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0); | |
270 | ||
271 | pwent_nip = NULL; | |
272 | return NSS_STATUS_NOTFOUND; | |
273 | } | |
274 | ||
275 | ||
276 | enum nss_status | |
277 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
278 | char *buffer, size_t buflen, int *errnop) | |
279 | { | |
280 | static const char *fct_name = "getpwnam_r"; | |
281 | static void *fct_start = NULL; | |
282 | enum nss_status status; | |
283 | service_user *nip; | |
284 | union { | |
285 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
286 | char *buffer, size_t buflen, int *errnop); | |
287 | void *ptr; | |
288 | } fct; | |
289 | int group_errno; | |
290 | ||
291 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
292 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
293 | return NSS_STATUS_UNAVAIL; | |
294 | ||
295 | nip = nss_passwd_nonlocal_database(); | |
296 | if (nip == NULL) | |
297 | return NSS_STATUS_UNAVAIL; | |
298 | if (fct_start == NULL) | |
299 | fct_start = __nss_lookup_function(nip, fct_name); | |
300 | fct.ptr = fct_start; | |
301 | do { | |
302 | if (fct.ptr == NULL) | |
303 | status = NSS_STATUS_UNAVAIL; | |
304 | else | |
305 | status = DL_CALL_FCT(fct.l, (name, pwd, buffer, buflen, errnop)); | |
306 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
307 | break; | |
308 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
309 | if (status != NSS_STATUS_SUCCESS) | |
310 | return status; | |
311 | ||
312 | status = check_nonlocal_uid(name, pwd->pw_uid, errnop); | |
313 | if (status != NSS_STATUS_SUCCESS) | |
314 | return status; | |
315 | ||
316 | if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) != | |
317 | NSS_STATUS_SUCCESS) | |
318 | pwd->pw_gid = 65534 /* nogroup */; | |
319 | return NSS_STATUS_SUCCESS; | |
320 | } | |
321 | ||
322 | enum nss_status | |
323 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
324 | char *buffer, size_t buflen, int *errnop) | |
325 | { | |
326 | static const char *fct_name = "getpwuid_r"; | |
327 | static void *fct_start = NULL; | |
328 | enum nss_status status; | |
329 | service_user *nip; | |
330 | union { | |
331 | enum nss_status (*l)(uid_t uid, struct passwd *pwd, | |
332 | char *buffer, size_t buflen, int *errnop); | |
333 | void *ptr; | |
334 | } fct; | |
335 | int group_errno; | |
336 | ||
337 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
338 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
339 | return NSS_STATUS_UNAVAIL; | |
340 | ||
341 | nip = nss_passwd_nonlocal_database(); | |
342 | if (nip == NULL) | |
343 | return NSS_STATUS_UNAVAIL; | |
344 | if (fct_start == NULL) | |
345 | fct_start = __nss_lookup_function(nip, fct_name); | |
346 | fct.ptr = fct_start; | |
347 | do { | |
348 | if (fct.ptr == NULL) | |
349 | status = NSS_STATUS_UNAVAIL; | |
350 | else | |
351 | status = DL_CALL_FCT(fct.l, (uid, pwd, buffer, buflen, errnop)); | |
352 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
353 | break; | |
354 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
355 | if (status != NSS_STATUS_SUCCESS) | |
356 | return status; | |
357 | ||
358 | status = check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, errnop); | |
359 | if (status != NSS_STATUS_SUCCESS) | |
360 | return status; | |
361 | ||
362 | if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) != | |
363 | NSS_STATUS_SUCCESS) | |
364 | pwd->pw_gid = 65534 /* nogroup */; | |
365 | return NSS_STATUS_SUCCESS; | |
366 | } |