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f6903667 AK |
1 | /* |
2 | * nonlocal-passwd.c | |
3 | * passwd database for nss_nonlocal proxy. | |
4 | * | |
48479fc7 TA |
5 | * Copyright © 2007 Anders Kaseorg <andersk@mit.edu> and Tim Abbott |
6 | * <tabbott@mit.edu> | |
f6903667 AK |
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 | ||
c1812233 AK |
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); | |
f7293a54 | 53 | |
f6903667 AK |
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 | ||
f6903667 AK |
66 | enum nss_status |
67 | check_nonlocal_uid(const char *user, uid_t uid, int *errnop) | |
68 | { | |
30fb3957 AK |
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; | |
f7293a54 | 79 | struct passwd pwbuf; |
f7293a54 | 80 | int old_errno = errno; |
c1812233 | 81 | |
8870ee9c | 82 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); |
f7293a54 AK |
83 | char *buf = malloc(buflen); |
84 | if (buf == NULL) { | |
f6903667 | 85 | *errnop = ENOMEM; |
f7293a54 | 86 | errno = old_errno; |
f6903667 AK |
87 | return NSS_STATUS_TRYAGAIN; |
88 | } | |
30fb3957 AK |
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 { | |
d905b369 | 98 | morebuf: |
c1812233 AK |
99 | if (fct.l == _nss_nonlocal_getpwuid_r) |
100 | status = NSS_STATUS_NOTFOUND; | |
101 | else | |
102 | status = DL_CALL_FCT(fct.l, (uid, &pwbuf, buf, buflen, errnop)); | |
d905b369 AK |
103 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { |
104 | free(buf); | |
105 | buflen *= 2; | |
106 | buf = malloc(buflen); | |
107 | if (buf == NULL) { | |
108 | *errnop = ENOMEM; | |
109 | errno = old_errno; | |
110 | return NSS_STATUS_TRYAGAIN; | |
111 | } | |
112 | goto morebuf; | |
113 | } | |
30fb3957 AK |
114 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); |
115 | ||
116 | if (status == NSS_STATUS_SUCCESS) { | |
f7293a54 | 117 | syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, pwbuf.pw_name); |
f6903667 | 118 | status = NSS_STATUS_NOTFOUND; |
30fb3957 AK |
119 | } else if (status != NSS_STATUS_TRYAGAIN) { |
120 | status = NSS_STATUS_SUCCESS; | |
f6903667 | 121 | } |
30fb3957 | 122 | |
f7293a54 | 123 | free(buf); |
f6903667 AK |
124 | return status; |
125 | } | |
126 | ||
cf338316 AK |
127 | enum nss_status |
128 | check_nonlocal_passwd(const char *user, struct passwd *pwd, int *errnop) | |
129 | { | |
130 | return check_nonlocal_uid(user, pwd->pw_uid, errnop); | |
131 | } | |
132 | ||
48479fc7 TA |
133 | enum nss_status |
134 | check_nonlocal_user(const char *user, int *errnop) | |
135 | { | |
30fb3957 AK |
136 | static const char *fct_name = "getpwnam_r"; |
137 | static service_user *startp = NULL; | |
138 | static void *fct_start = NULL; | |
139 | enum nss_status status; | |
140 | service_user *nip; | |
141 | union { | |
142 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
143 | char *buffer, size_t buflen, int *errnop); | |
144 | void *ptr; | |
145 | } fct; | |
48479fc7 | 146 | struct passwd pwbuf; |
48479fc7 | 147 | int old_errno = errno; |
c1812233 | 148 | |
8870ee9c | 149 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); |
48479fc7 TA |
150 | char *buf = malloc(buflen); |
151 | if (buf == NULL) { | |
152 | *errnop = ENOMEM; | |
153 | errno = old_errno; | |
154 | return NSS_STATUS_TRYAGAIN; | |
155 | } | |
30fb3957 AK |
156 | |
157 | if (fct_start == NULL && | |
158 | __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { | |
159 | free(buf); | |
160 | return NSS_STATUS_UNAVAIL; | |
48479fc7 | 161 | } |
30fb3957 AK |
162 | nip = startp; |
163 | fct.ptr = fct_start; | |
164 | do { | |
d905b369 | 165 | morebuf: |
c1812233 AK |
166 | if (fct.l == _nss_nonlocal_getpwnam_r) |
167 | status = NSS_STATUS_NOTFOUND; | |
168 | else | |
169 | status = DL_CALL_FCT(fct.l, (user, &pwbuf, buf, buflen, errnop)); | |
d905b369 AK |
170 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { |
171 | free(buf); | |
172 | buflen *= 2; | |
173 | buf = malloc(buflen); | |
174 | if (buf == NULL) { | |
175 | *errnop = ENOMEM; | |
176 | errno = old_errno; | |
177 | return NSS_STATUS_TRYAGAIN; | |
178 | } | |
179 | goto morebuf; | |
180 | } | |
30fb3957 AK |
181 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); |
182 | ||
183 | if (status == NSS_STATUS_SUCCESS) | |
184 | status = NSS_STATUS_NOTFOUND; | |
185 | else if (status != NSS_STATUS_TRYAGAIN) | |
186 | status = NSS_STATUS_SUCCESS; | |
187 | ||
48479fc7 | 188 | free(buf); |
48479fc7 TA |
189 | return status; |
190 | } | |
f6903667 | 191 | |
1e78305d | 192 | |
f6903667 AK |
193 | static service_user *pwent_nip = NULL; |
194 | static void *pwent_fct_start; | |
195 | static union { | |
196 | enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen, | |
197 | int *errnop); | |
198 | void *ptr; | |
199 | } pwent_fct; | |
200 | static const char *pwent_fct_name = "getpwent_r"; | |
201 | ||
202 | enum nss_status | |
203 | _nss_nonlocal_setpwent(int stayopen) | |
204 | { | |
205 | static const char *fct_name = "setpwent"; | |
206 | static void *fct_start = NULL; | |
207 | enum nss_status status; | |
208 | service_user *nip; | |
209 | union { | |
210 | enum nss_status (*l)(int stayopen); | |
211 | void *ptr; | |
212 | } fct; | |
213 | ||
214 | nip = nss_passwd_nonlocal_database(); | |
215 | if (nip == NULL) | |
216 | return NSS_STATUS_UNAVAIL; | |
217 | if (fct_start == NULL) | |
218 | fct_start = __nss_lookup_function(nip, fct_name); | |
219 | fct.ptr = fct_start; | |
220 | do { | |
221 | if (fct.ptr == NULL) | |
222 | status = NSS_STATUS_UNAVAIL; | |
223 | else | |
224 | status = DL_CALL_FCT(fct.l, (stayopen)); | |
225 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
226 | if (status != NSS_STATUS_SUCCESS) | |
227 | return status; | |
228 | ||
229 | pwent_nip = nip; | |
230 | if (pwent_fct_start == NULL) | |
231 | pwent_fct_start = __nss_lookup_function(nip, pwent_fct_name); | |
232 | pwent_fct.ptr = pwent_fct_start; | |
233 | return NSS_STATUS_SUCCESS; | |
234 | } | |
235 | ||
236 | enum nss_status | |
237 | _nss_nonlocal_endpwent(void) | |
238 | { | |
239 | static const char *fct_name = "endpwent"; | |
240 | static void *fct_start = NULL; | |
241 | enum nss_status status; | |
242 | service_user *nip; | |
243 | union { | |
244 | enum nss_status (*l)(void); | |
245 | void *ptr; | |
246 | } fct; | |
247 | ||
248 | pwent_nip = NULL; | |
249 | ||
250 | nip = nss_passwd_nonlocal_database(); | |
251 | if (nip == NULL) | |
252 | return NSS_STATUS_UNAVAIL; | |
253 | if (fct_start == NULL) | |
254 | fct_start = __nss_lookup_function(nip, fct_name); | |
255 | fct.ptr = fct_start; | |
256 | do { | |
257 | if (fct.ptr == NULL) | |
258 | status = NSS_STATUS_UNAVAIL; | |
259 | else | |
260 | status = DL_CALL_FCT(fct.l, ()); | |
261 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
262 | return status; | |
263 | } | |
264 | ||
265 | enum nss_status | |
266 | _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, | |
267 | int *errnop) | |
268 | { | |
269 | enum nss_status status; | |
a360549e TA |
270 | |
271 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
c1812233 | 272 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
a360549e TA |
273 | return NSS_STATUS_UNAVAIL; |
274 | ||
f6903667 AK |
275 | if (pwent_nip == NULL) { |
276 | status = _nss_nonlocal_setpwent(0); | |
277 | if (status != NSS_STATUS_SUCCESS) | |
278 | return status; | |
279 | } | |
280 | do { | |
281 | if (pwent_fct.ptr == NULL) | |
282 | status = NSS_STATUS_UNAVAIL; | |
283 | else { | |
284 | int nonlocal_errno; | |
285 | do | |
a360549e | 286 | status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); |
f6903667 | 287 | while (status == NSS_STATUS_SUCCESS && |
cf338316 | 288 | check_nonlocal_passwd(pwd->pw_name, pwd, &nonlocal_errno) != NSS_STATUS_SUCCESS); |
f6903667 AK |
289 | } |
290 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
291 | return status; | |
292 | ||
293 | if (status == NSS_STATUS_SUCCESS) | |
294 | return NSS_STATUS_SUCCESS; | |
295 | } while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0); | |
296 | ||
297 | pwent_nip = NULL; | |
298 | return NSS_STATUS_NOTFOUND; | |
299 | } | |
300 | ||
301 | ||
302 | enum nss_status | |
303 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
304 | char *buffer, size_t buflen, int *errnop) | |
305 | { | |
306 | static const char *fct_name = "getpwnam_r"; | |
307 | static void *fct_start = NULL; | |
308 | enum nss_status status; | |
309 | service_user *nip; | |
310 | union { | |
311 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
312 | char *buffer, size_t buflen, int *errnop); | |
313 | void *ptr; | |
314 | } fct; | |
315 | int group_errno; | |
316 | ||
a360549e | 317 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 318 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
48479fc7 TA |
319 | return NSS_STATUS_UNAVAIL; |
320 | ||
f6903667 AK |
321 | nip = nss_passwd_nonlocal_database(); |
322 | if (nip == NULL) | |
323 | return NSS_STATUS_UNAVAIL; | |
324 | if (fct_start == NULL) | |
325 | fct_start = __nss_lookup_function(nip, fct_name); | |
326 | fct.ptr = fct_start; | |
327 | do { | |
328 | if (fct.ptr == NULL) | |
329 | status = NSS_STATUS_UNAVAIL; | |
330 | else | |
331 | status = DL_CALL_FCT(fct.l, (name, pwd, buffer, buflen, errnop)); | |
332 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
333 | break; | |
334 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
335 | if (status != NSS_STATUS_SUCCESS) | |
336 | return status; | |
337 | ||
22562df0 AK |
338 | if (strcmp(name, pwd->pw_name) != 0) { |
339 | syslog(LOG_ERR, "nss_nonlocal: discarding user %s from lookup for user %s\n", pwd->pw_name, name); | |
340 | return NSS_STATUS_NOTFOUND; | |
341 | } | |
342 | ||
cf338316 | 343 | status = check_nonlocal_passwd(name, pwd, errnop); |
f6903667 AK |
344 | if (status != NSS_STATUS_SUCCESS) |
345 | return status; | |
346 | ||
347 | if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) != | |
348 | NSS_STATUS_SUCCESS) | |
349 | pwd->pw_gid = 65534 /* nogroup */; | |
350 | return NSS_STATUS_SUCCESS; | |
351 | } | |
352 | ||
353 | enum nss_status | |
354 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
355 | char *buffer, size_t buflen, int *errnop) | |
356 | { | |
357 | static const char *fct_name = "getpwuid_r"; | |
358 | static void *fct_start = NULL; | |
359 | enum nss_status status; | |
360 | service_user *nip; | |
361 | union { | |
362 | enum nss_status (*l)(uid_t uid, struct passwd *pwd, | |
363 | char *buffer, size_t buflen, int *errnop); | |
364 | void *ptr; | |
365 | } fct; | |
366 | int group_errno; | |
367 | ||
a360549e | 368 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 369 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
f6903667 AK |
370 | return NSS_STATUS_UNAVAIL; |
371 | ||
372 | nip = nss_passwd_nonlocal_database(); | |
373 | if (nip == NULL) | |
374 | return NSS_STATUS_UNAVAIL; | |
375 | if (fct_start == NULL) | |
376 | fct_start = __nss_lookup_function(nip, fct_name); | |
377 | fct.ptr = fct_start; | |
378 | do { | |
379 | if (fct.ptr == NULL) | |
380 | status = NSS_STATUS_UNAVAIL; | |
381 | else | |
382 | status = DL_CALL_FCT(fct.l, (uid, pwd, buffer, buflen, errnop)); | |
383 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
384 | break; | |
385 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
386 | if (status != NSS_STATUS_SUCCESS) | |
387 | return status; | |
388 | ||
cf338316 | 389 | status = check_nonlocal_passwd(pwd->pw_name, pwd, errnop); |
f6903667 AK |
390 | if (status != NSS_STATUS_SUCCESS) |
391 | return status; | |
392 | ||
393 | if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) != | |
394 | NSS_STATUS_SUCCESS) | |
395 | pwd->pw_gid = 65534 /* nogroup */; | |
396 | return NSS_STATUS_SUCCESS; | |
397 | } |