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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 AK |
81 | |
82 | int 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 | ||
48479fc7 TA |
127 | enum nss_status |
128 | check_nonlocal_user(const char *user, int *errnop) | |
129 | { | |
30fb3957 AK |
130 | static const char *fct_name = "getpwnam_r"; |
131 | static service_user *startp = NULL; | |
132 | static void *fct_start = NULL; | |
133 | enum nss_status status; | |
134 | service_user *nip; | |
135 | union { | |
136 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
137 | char *buffer, size_t buflen, int *errnop); | |
138 | void *ptr; | |
139 | } fct; | |
48479fc7 | 140 | struct passwd pwbuf; |
48479fc7 | 141 | int old_errno = errno; |
c1812233 AK |
142 | |
143 | int buflen = sysconf(_SC_GETPW_R_SIZE_MAX); | |
48479fc7 TA |
144 | char *buf = malloc(buflen); |
145 | if (buf == NULL) { | |
146 | *errnop = ENOMEM; | |
147 | errno = old_errno; | |
148 | return NSS_STATUS_TRYAGAIN; | |
149 | } | |
30fb3957 AK |
150 | |
151 | if (fct_start == NULL && | |
152 | __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { | |
153 | free(buf); | |
154 | return NSS_STATUS_UNAVAIL; | |
48479fc7 | 155 | } |
30fb3957 AK |
156 | nip = startp; |
157 | fct.ptr = fct_start; | |
158 | do { | |
d905b369 | 159 | morebuf: |
c1812233 AK |
160 | if (fct.l == _nss_nonlocal_getpwnam_r) |
161 | status = NSS_STATUS_NOTFOUND; | |
162 | else | |
163 | status = DL_CALL_FCT(fct.l, (user, &pwbuf, buf, buflen, errnop)); | |
d905b369 AK |
164 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { |
165 | free(buf); | |
166 | buflen *= 2; | |
167 | buf = malloc(buflen); | |
168 | if (buf == NULL) { | |
169 | *errnop = ENOMEM; | |
170 | errno = old_errno; | |
171 | return NSS_STATUS_TRYAGAIN; | |
172 | } | |
173 | goto morebuf; | |
174 | } | |
30fb3957 AK |
175 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); |
176 | ||
177 | if (status == NSS_STATUS_SUCCESS) | |
178 | status = NSS_STATUS_NOTFOUND; | |
179 | else if (status != NSS_STATUS_TRYAGAIN) | |
180 | status = NSS_STATUS_SUCCESS; | |
181 | ||
48479fc7 | 182 | free(buf); |
48479fc7 TA |
183 | return status; |
184 | } | |
f6903667 | 185 | |
1e78305d | 186 | |
f6903667 AK |
187 | static service_user *pwent_nip = NULL; |
188 | static void *pwent_fct_start; | |
189 | static union { | |
190 | enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen, | |
191 | int *errnop); | |
192 | void *ptr; | |
193 | } pwent_fct; | |
194 | static const char *pwent_fct_name = "getpwent_r"; | |
195 | ||
196 | enum nss_status | |
197 | _nss_nonlocal_setpwent(int stayopen) | |
198 | { | |
199 | static const char *fct_name = "setpwent"; | |
200 | static void *fct_start = NULL; | |
201 | enum nss_status status; | |
202 | service_user *nip; | |
203 | union { | |
204 | enum nss_status (*l)(int stayopen); | |
205 | void *ptr; | |
206 | } fct; | |
207 | ||
208 | nip = nss_passwd_nonlocal_database(); | |
209 | if (nip == NULL) | |
210 | return NSS_STATUS_UNAVAIL; | |
211 | if (fct_start == NULL) | |
212 | fct_start = __nss_lookup_function(nip, fct_name); | |
213 | fct.ptr = fct_start; | |
214 | do { | |
215 | if (fct.ptr == NULL) | |
216 | status = NSS_STATUS_UNAVAIL; | |
217 | else | |
218 | status = DL_CALL_FCT(fct.l, (stayopen)); | |
219 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
220 | if (status != NSS_STATUS_SUCCESS) | |
221 | return status; | |
222 | ||
223 | pwent_nip = nip; | |
224 | if (pwent_fct_start == NULL) | |
225 | pwent_fct_start = __nss_lookup_function(nip, pwent_fct_name); | |
226 | pwent_fct.ptr = pwent_fct_start; | |
227 | return NSS_STATUS_SUCCESS; | |
228 | } | |
229 | ||
230 | enum nss_status | |
231 | _nss_nonlocal_endpwent(void) | |
232 | { | |
233 | static const char *fct_name = "endpwent"; | |
234 | static void *fct_start = NULL; | |
235 | enum nss_status status; | |
236 | service_user *nip; | |
237 | union { | |
238 | enum nss_status (*l)(void); | |
239 | void *ptr; | |
240 | } fct; | |
241 | ||
242 | pwent_nip = NULL; | |
243 | ||
244 | nip = nss_passwd_nonlocal_database(); | |
245 | if (nip == NULL) | |
246 | return NSS_STATUS_UNAVAIL; | |
247 | if (fct_start == NULL) | |
248 | fct_start = __nss_lookup_function(nip, fct_name); | |
249 | fct.ptr = fct_start; | |
250 | do { | |
251 | if (fct.ptr == NULL) | |
252 | status = NSS_STATUS_UNAVAIL; | |
253 | else | |
254 | status = DL_CALL_FCT(fct.l, ()); | |
255 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
256 | return status; | |
257 | } | |
258 | ||
259 | enum nss_status | |
260 | _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, | |
261 | int *errnop) | |
262 | { | |
263 | enum nss_status status; | |
a360549e TA |
264 | |
265 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
c1812233 | 266 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
a360549e TA |
267 | return NSS_STATUS_UNAVAIL; |
268 | ||
f6903667 AK |
269 | if (pwent_nip == NULL) { |
270 | status = _nss_nonlocal_setpwent(0); | |
271 | if (status != NSS_STATUS_SUCCESS) | |
272 | return status; | |
273 | } | |
274 | do { | |
275 | if (pwent_fct.ptr == NULL) | |
276 | status = NSS_STATUS_UNAVAIL; | |
277 | else { | |
278 | int nonlocal_errno; | |
279 | do | |
a360549e | 280 | status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); |
f6903667 AK |
281 | while (status == NSS_STATUS_SUCCESS && |
282 | check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, &nonlocal_errno) != NSS_STATUS_SUCCESS); | |
283 | } | |
284 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
285 | return status; | |
286 | ||
287 | if (status == NSS_STATUS_SUCCESS) | |
288 | return NSS_STATUS_SUCCESS; | |
289 | } while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0); | |
290 | ||
291 | pwent_nip = NULL; | |
292 | return NSS_STATUS_NOTFOUND; | |
293 | } | |
294 | ||
295 | ||
296 | enum nss_status | |
297 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
298 | char *buffer, size_t buflen, int *errnop) | |
299 | { | |
300 | static const char *fct_name = "getpwnam_r"; | |
301 | static void *fct_start = NULL; | |
302 | enum nss_status status; | |
303 | service_user *nip; | |
304 | union { | |
305 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
306 | char *buffer, size_t buflen, int *errnop); | |
307 | void *ptr; | |
308 | } fct; | |
309 | int group_errno; | |
310 | ||
a360549e | 311 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 312 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
48479fc7 TA |
313 | return NSS_STATUS_UNAVAIL; |
314 | ||
f6903667 AK |
315 | nip = nss_passwd_nonlocal_database(); |
316 | if (nip == NULL) | |
317 | return NSS_STATUS_UNAVAIL; | |
318 | if (fct_start == NULL) | |
319 | fct_start = __nss_lookup_function(nip, fct_name); | |
320 | fct.ptr = fct_start; | |
321 | do { | |
322 | if (fct.ptr == NULL) | |
323 | status = NSS_STATUS_UNAVAIL; | |
324 | else | |
325 | status = DL_CALL_FCT(fct.l, (name, pwd, buffer, buflen, errnop)); | |
326 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
327 | break; | |
328 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
329 | if (status != NSS_STATUS_SUCCESS) | |
330 | return status; | |
331 | ||
332 | status = check_nonlocal_uid(name, pwd->pw_uid, errnop); | |
333 | if (status != NSS_STATUS_SUCCESS) | |
334 | return status; | |
335 | ||
336 | if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) != | |
337 | NSS_STATUS_SUCCESS) | |
338 | pwd->pw_gid = 65534 /* nogroup */; | |
339 | return NSS_STATUS_SUCCESS; | |
340 | } | |
341 | ||
342 | enum nss_status | |
343 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
344 | char *buffer, size_t buflen, int *errnop) | |
345 | { | |
346 | static const char *fct_name = "getpwuid_r"; | |
347 | static void *fct_start = NULL; | |
348 | enum nss_status status; | |
349 | service_user *nip; | |
350 | union { | |
351 | enum nss_status (*l)(uid_t uid, struct passwd *pwd, | |
352 | char *buffer, size_t buflen, int *errnop); | |
353 | void *ptr; | |
354 | } fct; | |
355 | int group_errno; | |
356 | ||
a360549e | 357 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 358 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
f6903667 AK |
359 | return NSS_STATUS_UNAVAIL; |
360 | ||
361 | nip = nss_passwd_nonlocal_database(); | |
362 | if (nip == NULL) | |
363 | return NSS_STATUS_UNAVAIL; | |
364 | if (fct_start == NULL) | |
365 | fct_start = __nss_lookup_function(nip, fct_name); | |
366 | fct.ptr = fct_start; | |
367 | do { | |
368 | if (fct.ptr == NULL) | |
369 | status = NSS_STATUS_UNAVAIL; | |
370 | else | |
371 | status = DL_CALL_FCT(fct.l, (uid, pwd, buffer, buflen, errnop)); | |
372 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
373 | break; | |
374 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
375 | if (status != NSS_STATUS_SUCCESS) | |
376 | return status; | |
377 | ||
378 | status = check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, errnop); | |
379 | if (status != NSS_STATUS_SUCCESS) | |
380 | return status; | |
381 | ||
382 | if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) != | |
383 | NSS_STATUS_SUCCESS) | |
384 | pwd->pw_gid = 65534 /* nogroup */; | |
385 | return NSS_STATUS_SUCCESS; | |
386 | } |