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b1d4f8e1 LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2010 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU Lesser General Public License as published by | |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <pwd.h> | |
23 | #include <grp.h> | |
24 | ||
25 | #include "user-util.h" | |
26 | #include "macro.h" | |
27 | #include "util.h" | |
28 | #include "string-util.h" | |
29 | #include "path-util.h" | |
30 | ||
31 | bool uid_is_valid(uid_t uid) { | |
32 | ||
33 | /* Some libc APIs use UID_INVALID as special placeholder */ | |
b1d52773 | 34 | if (uid == (uid_t) UINT32_C(0xFFFFFFFF)) |
b1d4f8e1 LP |
35 | return false; |
36 | ||
37 | /* A long time ago UIDs where 16bit, hence explicitly avoid the 16bit -1 too */ | |
b1d52773 | 38 | if (uid == (uid_t) UINT32_C(0xFFFF)) |
b1d4f8e1 LP |
39 | return false; |
40 | ||
41 | return true; | |
42 | } | |
43 | ||
b1d52773 LP |
44 | int parse_uid(const char *s, uid_t *ret) { |
45 | uint32_t uid = 0; | |
b1d4f8e1 LP |
46 | int r; |
47 | ||
48 | assert(s); | |
49 | ||
b1d52773 LP |
50 | assert_cc(sizeof(uid_t) == sizeof(uint32_t)); |
51 | r = safe_atou32(s, &uid); | |
b1d4f8e1 LP |
52 | if (r < 0) |
53 | return r; | |
54 | ||
b1d4f8e1 LP |
55 | if (!uid_is_valid(uid)) |
56 | return -ENXIO; /* we return ENXIO instead of EINVAL | |
57 | * here, to make it easy to distuingish | |
58 | * invalid numeric uids invalid | |
59 | * strings. */ | |
60 | ||
b1d52773 LP |
61 | if (ret) |
62 | *ret = uid; | |
b1d4f8e1 LP |
63 | |
64 | return 0; | |
65 | } | |
66 | ||
b1d4f8e1 LP |
67 | char* getlogname_malloc(void) { |
68 | uid_t uid; | |
69 | struct stat st; | |
70 | ||
71 | if (isatty(STDIN_FILENO) && fstat(STDIN_FILENO, &st) >= 0) | |
72 | uid = st.st_uid; | |
73 | else | |
74 | uid = getuid(); | |
75 | ||
d0260817 | 76 | return uid_to_name(uid); |
b1d4f8e1 LP |
77 | } |
78 | ||
79 | char *getusername_malloc(void) { | |
80 | const char *e; | |
81 | ||
82 | e = getenv("USER"); | |
83 | if (e) | |
84 | return strdup(e); | |
85 | ||
d0260817 | 86 | return uid_to_name(getuid()); |
b1d4f8e1 LP |
87 | } |
88 | ||
89 | int get_user_creds( | |
90 | const char **username, | |
91 | uid_t *uid, gid_t *gid, | |
92 | const char **home, | |
93 | const char **shell) { | |
94 | ||
95 | struct passwd *p; | |
96 | uid_t u; | |
97 | ||
98 | assert(username); | |
99 | assert(*username); | |
100 | ||
101 | /* We enforce some special rules for uid=0: in order to avoid | |
102 | * NSS lookups for root we hardcode its data. */ | |
103 | ||
104 | if (streq(*username, "root") || streq(*username, "0")) { | |
105 | *username = "root"; | |
106 | ||
107 | if (uid) | |
108 | *uid = 0; | |
109 | ||
110 | if (gid) | |
111 | *gid = 0; | |
112 | ||
113 | if (home) | |
114 | *home = "/root"; | |
115 | ||
116 | if (shell) | |
117 | *shell = "/bin/sh"; | |
118 | ||
119 | return 0; | |
120 | } | |
121 | ||
122 | if (parse_uid(*username, &u) >= 0) { | |
123 | errno = 0; | |
124 | p = getpwuid(u); | |
125 | ||
126 | /* If there are multiple users with the same id, make | |
127 | * sure to leave $USER to the configured value instead | |
128 | * of the first occurrence in the database. However if | |
129 | * the uid was configured by a numeric uid, then let's | |
130 | * pick the real username from /etc/passwd. */ | |
131 | if (p) | |
132 | *username = p->pw_name; | |
133 | } else { | |
134 | errno = 0; | |
135 | p = getpwnam(*username); | |
136 | } | |
137 | ||
138 | if (!p) | |
139 | return errno > 0 ? -errno : -ESRCH; | |
140 | ||
67c7c892 LP |
141 | if (uid) { |
142 | if (!uid_is_valid(p->pw_uid)) | |
143 | return -EBADMSG; | |
144 | ||
b1d4f8e1 | 145 | *uid = p->pw_uid; |
67c7c892 LP |
146 | } |
147 | ||
148 | if (gid) { | |
149 | if (!gid_is_valid(p->pw_gid)) | |
150 | return -EBADMSG; | |
b1d4f8e1 | 151 | |
b1d4f8e1 | 152 | *gid = p->pw_gid; |
67c7c892 | 153 | } |
b1d4f8e1 LP |
154 | |
155 | if (home) | |
156 | *home = p->pw_dir; | |
157 | ||
158 | if (shell) | |
159 | *shell = p->pw_shell; | |
160 | ||
161 | return 0; | |
162 | } | |
163 | ||
164 | int get_group_creds(const char **groupname, gid_t *gid) { | |
165 | struct group *g; | |
166 | gid_t id; | |
167 | ||
168 | assert(groupname); | |
169 | ||
170 | /* We enforce some special rules for gid=0: in order to avoid | |
171 | * NSS lookups for root we hardcode its data. */ | |
172 | ||
173 | if (streq(*groupname, "root") || streq(*groupname, "0")) { | |
174 | *groupname = "root"; | |
175 | ||
176 | if (gid) | |
177 | *gid = 0; | |
178 | ||
179 | return 0; | |
180 | } | |
181 | ||
182 | if (parse_gid(*groupname, &id) >= 0) { | |
183 | errno = 0; | |
184 | g = getgrgid(id); | |
185 | ||
186 | if (g) | |
187 | *groupname = g->gr_name; | |
188 | } else { | |
189 | errno = 0; | |
190 | g = getgrnam(*groupname); | |
191 | } | |
192 | ||
193 | if (!g) | |
194 | return errno > 0 ? -errno : -ESRCH; | |
195 | ||
67c7c892 LP |
196 | if (gid) { |
197 | if (!gid_is_valid(g->gr_gid)) | |
198 | return -EBADMSG; | |
199 | ||
b1d4f8e1 | 200 | *gid = g->gr_gid; |
67c7c892 | 201 | } |
b1d4f8e1 LP |
202 | |
203 | return 0; | |
204 | } | |
205 | ||
206 | char* uid_to_name(uid_t uid) { | |
d0260817 LP |
207 | char *ret; |
208 | int r; | |
b1d4f8e1 | 209 | |
d0260817 | 210 | /* Shortcut things to avoid NSS lookups */ |
b1d4f8e1 LP |
211 | if (uid == 0) |
212 | return strdup("root"); | |
213 | ||
d0260817 LP |
214 | if (uid_is_valid(uid)) { |
215 | long bufsize; | |
216 | ||
217 | bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); | |
218 | if (bufsize <= 0) | |
219 | bufsize = 4096; | |
220 | ||
221 | for (;;) { | |
222 | struct passwd pwbuf, *pw = NULL; | |
223 | _cleanup_free_ char *buf = NULL; | |
224 | ||
225 | buf = malloc(bufsize); | |
226 | if (!buf) | |
227 | return NULL; | |
228 | ||
229 | r = getpwuid_r(uid, &pwbuf, buf, (size_t) bufsize, &pw); | |
230 | if (r == 0 && pw) | |
231 | return strdup(pw->pw_name); | |
232 | if (r != ERANGE) | |
233 | break; | |
234 | ||
235 | bufsize *= 2; | |
236 | } | |
237 | } | |
b1d4f8e1 | 238 | |
d0260817 | 239 | if (asprintf(&ret, UID_FMT, uid) < 0) |
b1d4f8e1 LP |
240 | return NULL; |
241 | ||
d0260817 | 242 | return ret; |
b1d4f8e1 LP |
243 | } |
244 | ||
245 | char* gid_to_name(gid_t gid) { | |
d0260817 LP |
246 | char *ret; |
247 | int r; | |
b1d4f8e1 LP |
248 | |
249 | if (gid == 0) | |
250 | return strdup("root"); | |
251 | ||
d0260817 LP |
252 | if (gid_is_valid(gid)) { |
253 | long bufsize; | |
254 | ||
255 | bufsize = sysconf(_SC_GETGR_R_SIZE_MAX); | |
256 | if (bufsize <= 0) | |
257 | bufsize = 4096; | |
258 | ||
259 | for (;;) { | |
260 | struct group grbuf, *gr = NULL; | |
261 | _cleanup_free_ char *buf = NULL; | |
262 | ||
263 | buf = malloc(bufsize); | |
264 | if (!buf) | |
265 | return NULL; | |
266 | ||
267 | r = getgrgid_r(gid, &grbuf, buf, (size_t) bufsize, &gr); | |
268 | if (r == 0 && gr) | |
269 | return strdup(gr->gr_name); | |
270 | if (r != ERANGE) | |
271 | break; | |
272 | ||
273 | bufsize *= 2; | |
274 | } | |
275 | } | |
b1d4f8e1 | 276 | |
d0260817 | 277 | if (asprintf(&ret, GID_FMT, gid) < 0) |
b1d4f8e1 LP |
278 | return NULL; |
279 | ||
d0260817 | 280 | return ret; |
b1d4f8e1 LP |
281 | } |
282 | ||
283 | int in_gid(gid_t gid) { | |
284 | gid_t *gids; | |
285 | int ngroups_max, r, i; | |
286 | ||
287 | if (getgid() == gid) | |
288 | return 1; | |
289 | ||
290 | if (getegid() == gid) | |
291 | return 1; | |
292 | ||
67c7c892 LP |
293 | if (!gid_is_valid(gid)) |
294 | return -EINVAL; | |
295 | ||
b1d4f8e1 LP |
296 | ngroups_max = sysconf(_SC_NGROUPS_MAX); |
297 | assert(ngroups_max > 0); | |
298 | ||
299 | gids = alloca(sizeof(gid_t) * ngroups_max); | |
300 | ||
301 | r = getgroups(ngroups_max, gids); | |
302 | if (r < 0) | |
303 | return -errno; | |
304 | ||
305 | for (i = 0; i < r; i++) | |
306 | if (gids[i] == gid) | |
307 | return 1; | |
308 | ||
309 | return 0; | |
310 | } | |
311 | ||
312 | int in_group(const char *name) { | |
313 | int r; | |
314 | gid_t gid; | |
315 | ||
316 | r = get_group_creds(&name, &gid); | |
317 | if (r < 0) | |
318 | return r; | |
319 | ||
320 | return in_gid(gid); | |
321 | } | |
322 | ||
323 | int get_home_dir(char **_h) { | |
324 | struct passwd *p; | |
325 | const char *e; | |
326 | char *h; | |
327 | uid_t u; | |
328 | ||
329 | assert(_h); | |
330 | ||
331 | /* Take the user specified one */ | |
332 | e = secure_getenv("HOME"); | |
333 | if (e && path_is_absolute(e)) { | |
334 | h = strdup(e); | |
335 | if (!h) | |
336 | return -ENOMEM; | |
337 | ||
338 | *_h = h; | |
339 | return 0; | |
340 | } | |
341 | ||
342 | /* Hardcode home directory for root to avoid NSS */ | |
343 | u = getuid(); | |
344 | if (u == 0) { | |
345 | h = strdup("/root"); | |
346 | if (!h) | |
347 | return -ENOMEM; | |
348 | ||
349 | *_h = h; | |
350 | return 0; | |
351 | } | |
352 | ||
353 | /* Check the database... */ | |
354 | errno = 0; | |
355 | p = getpwuid(u); | |
356 | if (!p) | |
357 | return errno > 0 ? -errno : -ESRCH; | |
358 | ||
359 | if (!path_is_absolute(p->pw_dir)) | |
360 | return -EINVAL; | |
361 | ||
362 | h = strdup(p->pw_dir); | |
363 | if (!h) | |
364 | return -ENOMEM; | |
365 | ||
366 | *_h = h; | |
367 | return 0; | |
368 | } | |
369 | ||
370 | int get_shell(char **_s) { | |
371 | struct passwd *p; | |
372 | const char *e; | |
373 | char *s; | |
374 | uid_t u; | |
375 | ||
376 | assert(_s); | |
377 | ||
378 | /* Take the user specified one */ | |
379 | e = getenv("SHELL"); | |
380 | if (e) { | |
381 | s = strdup(e); | |
382 | if (!s) | |
383 | return -ENOMEM; | |
384 | ||
385 | *_s = s; | |
386 | return 0; | |
387 | } | |
388 | ||
389 | /* Hardcode home directory for root to avoid NSS */ | |
390 | u = getuid(); | |
391 | if (u == 0) { | |
392 | s = strdup("/bin/sh"); | |
393 | if (!s) | |
394 | return -ENOMEM; | |
395 | ||
396 | *_s = s; | |
397 | return 0; | |
398 | } | |
399 | ||
400 | /* Check the database... */ | |
401 | errno = 0; | |
402 | p = getpwuid(u); | |
403 | if (!p) | |
404 | return errno > 0 ? -errno : -ESRCH; | |
405 | ||
406 | if (!path_is_absolute(p->pw_shell)) | |
407 | return -EINVAL; | |
408 | ||
409 | s = strdup(p->pw_shell); | |
410 | if (!s) | |
411 | return -ENOMEM; | |
412 | ||
413 | *_s = s; | |
414 | return 0; | |
415 | } | |
416 | ||
417 | int reset_uid_gid(void) { | |
418 | ||
419 | if (setgroups(0, NULL) < 0) | |
420 | return -errno; | |
421 | ||
422 | if (setresgid(0, 0, 0) < 0) | |
423 | return -errno; | |
424 | ||
425 | if (setresuid(0, 0, 0) < 0) | |
426 | return -errno; | |
427 | ||
428 | return 0; | |
429 | } |