]>
Commit | Line | Data |
---|---|---|
b1d4f8e1 LP |
1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright 2010 Lennart Poettering | |
5 | ||
6 | systemd is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 2.1 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | systemd is distributed in the hope that it will be useful, but | |
12 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
18 | ***/ | |
19 | ||
11c3a366 TA |
20 | #include <alloca.h> |
21 | #include <errno.h> | |
22 | #include <fcntl.h> | |
b1d4f8e1 | 23 | #include <grp.h> |
cf0fbc49 | 24 | #include <pwd.h> |
11c3a366 TA |
25 | #include <stddef.h> |
26 | #include <stdint.h> | |
27 | #include <stdio.h> | |
28 | #include <stdlib.h> | |
29 | #include <string.h> | |
30 | #include <sys/stat.h> | |
31 | #include <unistd.h> | |
e4631b48 | 32 | #include <utmp.h> |
b1d4f8e1 | 33 | |
b5efdb8a | 34 | #include "alloc-util.h" |
e929bee0 | 35 | #include "fd-util.h" |
93cc7779 | 36 | #include "formats-util.h" |
b1d4f8e1 | 37 | #include "macro.h" |
be39ccf3 | 38 | #include "missing.h" |
6bedfcbb | 39 | #include "parse-util.h" |
b1d4f8e1 | 40 | #include "path-util.h" |
6bedfcbb | 41 | #include "string-util.h" |
be39ccf3 | 42 | #include "strv.h" |
6bedfcbb | 43 | #include "user-util.h" |
e4631b48 | 44 | #include "utf8.h" |
b1d4f8e1 LP |
45 | |
46 | bool uid_is_valid(uid_t uid) { | |
47 | ||
48 | /* Some libc APIs use UID_INVALID as special placeholder */ | |
b1d52773 | 49 | if (uid == (uid_t) UINT32_C(0xFFFFFFFF)) |
b1d4f8e1 LP |
50 | return false; |
51 | ||
52 | /* A long time ago UIDs where 16bit, hence explicitly avoid the 16bit -1 too */ | |
b1d52773 | 53 | if (uid == (uid_t) UINT32_C(0xFFFF)) |
b1d4f8e1 LP |
54 | return false; |
55 | ||
56 | return true; | |
57 | } | |
58 | ||
b1d52773 LP |
59 | int parse_uid(const char *s, uid_t *ret) { |
60 | uint32_t uid = 0; | |
b1d4f8e1 LP |
61 | int r; |
62 | ||
63 | assert(s); | |
64 | ||
b1d52773 LP |
65 | assert_cc(sizeof(uid_t) == sizeof(uint32_t)); |
66 | r = safe_atou32(s, &uid); | |
b1d4f8e1 LP |
67 | if (r < 0) |
68 | return r; | |
69 | ||
b1d4f8e1 LP |
70 | if (!uid_is_valid(uid)) |
71 | return -ENXIO; /* we return ENXIO instead of EINVAL | |
72 | * here, to make it easy to distuingish | |
ba60af86 | 73 | * invalid numeric uids from invalid |
b1d4f8e1 LP |
74 | * strings. */ |
75 | ||
b1d52773 LP |
76 | if (ret) |
77 | *ret = uid; | |
b1d4f8e1 LP |
78 | |
79 | return 0; | |
80 | } | |
81 | ||
b1d4f8e1 LP |
82 | char* getlogname_malloc(void) { |
83 | uid_t uid; | |
84 | struct stat st; | |
85 | ||
86 | if (isatty(STDIN_FILENO) && fstat(STDIN_FILENO, &st) >= 0) | |
87 | uid = st.st_uid; | |
88 | else | |
89 | uid = getuid(); | |
90 | ||
d0260817 | 91 | return uid_to_name(uid); |
b1d4f8e1 LP |
92 | } |
93 | ||
94 | char *getusername_malloc(void) { | |
95 | const char *e; | |
96 | ||
97 | e = getenv("USER"); | |
98 | if (e) | |
99 | return strdup(e); | |
100 | ||
d0260817 | 101 | return uid_to_name(getuid()); |
b1d4f8e1 LP |
102 | } |
103 | ||
104 | int get_user_creds( | |
105 | const char **username, | |
106 | uid_t *uid, gid_t *gid, | |
107 | const char **home, | |
108 | const char **shell) { | |
109 | ||
110 | struct passwd *p; | |
111 | uid_t u; | |
112 | ||
113 | assert(username); | |
114 | assert(*username); | |
115 | ||
116 | /* We enforce some special rules for uid=0: in order to avoid | |
117 | * NSS lookups for root we hardcode its data. */ | |
118 | ||
119 | if (streq(*username, "root") || streq(*username, "0")) { | |
120 | *username = "root"; | |
121 | ||
122 | if (uid) | |
123 | *uid = 0; | |
124 | ||
125 | if (gid) | |
126 | *gid = 0; | |
127 | ||
128 | if (home) | |
129 | *home = "/root"; | |
130 | ||
131 | if (shell) | |
132 | *shell = "/bin/sh"; | |
133 | ||
134 | return 0; | |
135 | } | |
136 | ||
137 | if (parse_uid(*username, &u) >= 0) { | |
138 | errno = 0; | |
139 | p = getpwuid(u); | |
140 | ||
141 | /* If there are multiple users with the same id, make | |
142 | * sure to leave $USER to the configured value instead | |
143 | * of the first occurrence in the database. However if | |
144 | * the uid was configured by a numeric uid, then let's | |
145 | * pick the real username from /etc/passwd. */ | |
146 | if (p) | |
147 | *username = p->pw_name; | |
148 | } else { | |
149 | errno = 0; | |
150 | p = getpwnam(*username); | |
151 | } | |
152 | ||
153 | if (!p) | |
154 | return errno > 0 ? -errno : -ESRCH; | |
155 | ||
67c7c892 LP |
156 | if (uid) { |
157 | if (!uid_is_valid(p->pw_uid)) | |
158 | return -EBADMSG; | |
159 | ||
b1d4f8e1 | 160 | *uid = p->pw_uid; |
67c7c892 LP |
161 | } |
162 | ||
163 | if (gid) { | |
164 | if (!gid_is_valid(p->pw_gid)) | |
165 | return -EBADMSG; | |
b1d4f8e1 | 166 | |
b1d4f8e1 | 167 | *gid = p->pw_gid; |
67c7c892 | 168 | } |
b1d4f8e1 LP |
169 | |
170 | if (home) | |
171 | *home = p->pw_dir; | |
172 | ||
173 | if (shell) | |
174 | *shell = p->pw_shell; | |
175 | ||
176 | return 0; | |
177 | } | |
178 | ||
be39ccf3 LP |
179 | int get_user_creds_clean( |
180 | const char **username, | |
181 | uid_t *uid, gid_t *gid, | |
182 | const char **home, | |
183 | const char **shell) { | |
184 | ||
185 | int r; | |
186 | ||
187 | /* Like get_user_creds(), but resets home/shell to NULL if they don't contain anything relevant. */ | |
188 | ||
189 | r = get_user_creds(username, uid, gid, home, shell); | |
190 | if (r < 0) | |
191 | return r; | |
192 | ||
193 | if (shell && | |
194 | (isempty(*shell) || PATH_IN_SET(*shell, | |
195 | "/bin/nologin", | |
196 | "/sbin/nologin", | |
197 | "/usr/bin/nologin", | |
198 | "/usr/sbin/nologin"))) | |
199 | *shell = NULL; | |
200 | ||
201 | if (home && | |
202 | (isempty(*home) || path_equal(*home, "/"))) | |
203 | *home = NULL; | |
204 | ||
205 | return 0; | |
206 | } | |
207 | ||
b1d4f8e1 LP |
208 | int get_group_creds(const char **groupname, gid_t *gid) { |
209 | struct group *g; | |
210 | gid_t id; | |
211 | ||
212 | assert(groupname); | |
213 | ||
214 | /* We enforce some special rules for gid=0: in order to avoid | |
215 | * NSS lookups for root we hardcode its data. */ | |
216 | ||
217 | if (streq(*groupname, "root") || streq(*groupname, "0")) { | |
218 | *groupname = "root"; | |
219 | ||
220 | if (gid) | |
221 | *gid = 0; | |
222 | ||
223 | return 0; | |
224 | } | |
225 | ||
226 | if (parse_gid(*groupname, &id) >= 0) { | |
227 | errno = 0; | |
228 | g = getgrgid(id); | |
229 | ||
230 | if (g) | |
231 | *groupname = g->gr_name; | |
232 | } else { | |
233 | errno = 0; | |
234 | g = getgrnam(*groupname); | |
235 | } | |
236 | ||
237 | if (!g) | |
238 | return errno > 0 ? -errno : -ESRCH; | |
239 | ||
67c7c892 LP |
240 | if (gid) { |
241 | if (!gid_is_valid(g->gr_gid)) | |
242 | return -EBADMSG; | |
243 | ||
b1d4f8e1 | 244 | *gid = g->gr_gid; |
67c7c892 | 245 | } |
b1d4f8e1 LP |
246 | |
247 | return 0; | |
248 | } | |
249 | ||
250 | char* uid_to_name(uid_t uid) { | |
d0260817 LP |
251 | char *ret; |
252 | int r; | |
b1d4f8e1 | 253 | |
d0260817 | 254 | /* Shortcut things to avoid NSS lookups */ |
b1d4f8e1 LP |
255 | if (uid == 0) |
256 | return strdup("root"); | |
257 | ||
d0260817 LP |
258 | if (uid_is_valid(uid)) { |
259 | long bufsize; | |
260 | ||
261 | bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); | |
262 | if (bufsize <= 0) | |
263 | bufsize = 4096; | |
264 | ||
265 | for (;;) { | |
266 | struct passwd pwbuf, *pw = NULL; | |
267 | _cleanup_free_ char *buf = NULL; | |
268 | ||
269 | buf = malloc(bufsize); | |
270 | if (!buf) | |
271 | return NULL; | |
272 | ||
273 | r = getpwuid_r(uid, &pwbuf, buf, (size_t) bufsize, &pw); | |
274 | if (r == 0 && pw) | |
275 | return strdup(pw->pw_name); | |
276 | if (r != ERANGE) | |
277 | break; | |
278 | ||
279 | bufsize *= 2; | |
280 | } | |
281 | } | |
b1d4f8e1 | 282 | |
d0260817 | 283 | if (asprintf(&ret, UID_FMT, uid) < 0) |
b1d4f8e1 LP |
284 | return NULL; |
285 | ||
d0260817 | 286 | return ret; |
b1d4f8e1 LP |
287 | } |
288 | ||
289 | char* gid_to_name(gid_t gid) { | |
d0260817 LP |
290 | char *ret; |
291 | int r; | |
b1d4f8e1 LP |
292 | |
293 | if (gid == 0) | |
294 | return strdup("root"); | |
295 | ||
d0260817 LP |
296 | if (gid_is_valid(gid)) { |
297 | long bufsize; | |
298 | ||
299 | bufsize = sysconf(_SC_GETGR_R_SIZE_MAX); | |
300 | if (bufsize <= 0) | |
301 | bufsize = 4096; | |
302 | ||
303 | for (;;) { | |
304 | struct group grbuf, *gr = NULL; | |
305 | _cleanup_free_ char *buf = NULL; | |
306 | ||
307 | buf = malloc(bufsize); | |
308 | if (!buf) | |
309 | return NULL; | |
310 | ||
311 | r = getgrgid_r(gid, &grbuf, buf, (size_t) bufsize, &gr); | |
312 | if (r == 0 && gr) | |
313 | return strdup(gr->gr_name); | |
314 | if (r != ERANGE) | |
315 | break; | |
316 | ||
317 | bufsize *= 2; | |
318 | } | |
319 | } | |
b1d4f8e1 | 320 | |
d0260817 | 321 | if (asprintf(&ret, GID_FMT, gid) < 0) |
b1d4f8e1 LP |
322 | return NULL; |
323 | ||
d0260817 | 324 | return ret; |
b1d4f8e1 LP |
325 | } |
326 | ||
327 | int in_gid(gid_t gid) { | |
328 | gid_t *gids; | |
329 | int ngroups_max, r, i; | |
330 | ||
331 | if (getgid() == gid) | |
332 | return 1; | |
333 | ||
334 | if (getegid() == gid) | |
335 | return 1; | |
336 | ||
67c7c892 LP |
337 | if (!gid_is_valid(gid)) |
338 | return -EINVAL; | |
339 | ||
b1d4f8e1 LP |
340 | ngroups_max = sysconf(_SC_NGROUPS_MAX); |
341 | assert(ngroups_max > 0); | |
342 | ||
343 | gids = alloca(sizeof(gid_t) * ngroups_max); | |
344 | ||
345 | r = getgroups(ngroups_max, gids); | |
346 | if (r < 0) | |
347 | return -errno; | |
348 | ||
349 | for (i = 0; i < r; i++) | |
350 | if (gids[i] == gid) | |
351 | return 1; | |
352 | ||
353 | return 0; | |
354 | } | |
355 | ||
356 | int in_group(const char *name) { | |
357 | int r; | |
358 | gid_t gid; | |
359 | ||
360 | r = get_group_creds(&name, &gid); | |
361 | if (r < 0) | |
362 | return r; | |
363 | ||
364 | return in_gid(gid); | |
365 | } | |
366 | ||
367 | int get_home_dir(char **_h) { | |
368 | struct passwd *p; | |
369 | const char *e; | |
370 | char *h; | |
371 | uid_t u; | |
372 | ||
373 | assert(_h); | |
374 | ||
375 | /* Take the user specified one */ | |
376 | e = secure_getenv("HOME"); | |
377 | if (e && path_is_absolute(e)) { | |
378 | h = strdup(e); | |
379 | if (!h) | |
380 | return -ENOMEM; | |
381 | ||
382 | *_h = h; | |
383 | return 0; | |
384 | } | |
385 | ||
386 | /* Hardcode home directory for root to avoid NSS */ | |
387 | u = getuid(); | |
388 | if (u == 0) { | |
389 | h = strdup("/root"); | |
390 | if (!h) | |
391 | return -ENOMEM; | |
392 | ||
393 | *_h = h; | |
394 | return 0; | |
395 | } | |
396 | ||
397 | /* Check the database... */ | |
398 | errno = 0; | |
399 | p = getpwuid(u); | |
400 | if (!p) | |
401 | return errno > 0 ? -errno : -ESRCH; | |
402 | ||
403 | if (!path_is_absolute(p->pw_dir)) | |
404 | return -EINVAL; | |
405 | ||
406 | h = strdup(p->pw_dir); | |
407 | if (!h) | |
408 | return -ENOMEM; | |
409 | ||
410 | *_h = h; | |
411 | return 0; | |
412 | } | |
413 | ||
414 | int get_shell(char **_s) { | |
415 | struct passwd *p; | |
416 | const char *e; | |
417 | char *s; | |
418 | uid_t u; | |
419 | ||
420 | assert(_s); | |
421 | ||
422 | /* Take the user specified one */ | |
423 | e = getenv("SHELL"); | |
424 | if (e) { | |
425 | s = strdup(e); | |
426 | if (!s) | |
427 | return -ENOMEM; | |
428 | ||
429 | *_s = s; | |
430 | return 0; | |
431 | } | |
432 | ||
433 | /* Hardcode home directory for root to avoid NSS */ | |
434 | u = getuid(); | |
435 | if (u == 0) { | |
436 | s = strdup("/bin/sh"); | |
437 | if (!s) | |
438 | return -ENOMEM; | |
439 | ||
440 | *_s = s; | |
441 | return 0; | |
442 | } | |
443 | ||
444 | /* Check the database... */ | |
445 | errno = 0; | |
446 | p = getpwuid(u); | |
447 | if (!p) | |
448 | return errno > 0 ? -errno : -ESRCH; | |
449 | ||
450 | if (!path_is_absolute(p->pw_shell)) | |
451 | return -EINVAL; | |
452 | ||
453 | s = strdup(p->pw_shell); | |
454 | if (!s) | |
455 | return -ENOMEM; | |
456 | ||
457 | *_s = s; | |
458 | return 0; | |
459 | } | |
460 | ||
461 | int reset_uid_gid(void) { | |
462 | ||
463 | if (setgroups(0, NULL) < 0) | |
464 | return -errno; | |
465 | ||
466 | if (setresgid(0, 0, 0) < 0) | |
467 | return -errno; | |
468 | ||
469 | if (setresuid(0, 0, 0) < 0) | |
470 | return -errno; | |
471 | ||
472 | return 0; | |
473 | } | |
e929bee0 LP |
474 | |
475 | int take_etc_passwd_lock(const char *root) { | |
476 | ||
477 | struct flock flock = { | |
478 | .l_type = F_WRLCK, | |
479 | .l_whence = SEEK_SET, | |
480 | .l_start = 0, | |
481 | .l_len = 0, | |
482 | }; | |
483 | ||
484 | const char *path; | |
485 | int fd, r; | |
486 | ||
487 | /* This is roughly the same as lckpwdf(), but not as awful. We | |
488 | * don't want to use alarm() and signals, hence we implement | |
489 | * our own trivial version of this. | |
490 | * | |
491 | * Note that shadow-utils also takes per-database locks in | |
492 | * addition to lckpwdf(). However, we don't given that they | |
61233823 | 493 | * are redundant as they invoke lckpwdf() first and keep |
e929bee0 LP |
494 | * it during everything they do. The per-database locks are |
495 | * awfully racy, and thus we just won't do them. */ | |
496 | ||
497 | if (root) | |
498 | path = prefix_roota(root, "/etc/.pwd.lock"); | |
499 | else | |
500 | path = "/etc/.pwd.lock"; | |
501 | ||
502 | fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0600); | |
503 | if (fd < 0) | |
504 | return -errno; | |
505 | ||
506 | r = fcntl(fd, F_SETLKW, &flock); | |
507 | if (r < 0) { | |
508 | safe_close(fd); | |
509 | return -errno; | |
510 | } | |
511 | ||
512 | return fd; | |
513 | } | |
e4631b48 LP |
514 | |
515 | bool valid_user_group_name(const char *u) { | |
516 | const char *i; | |
517 | long sz; | |
518 | ||
519 | /* Checks if the specified name is a valid user/group name. */ | |
520 | ||
521 | if (isempty(u)) | |
522 | return false; | |
523 | ||
524 | if (!(u[0] >= 'a' && u[0] <= 'z') && | |
525 | !(u[0] >= 'A' && u[0] <= 'Z') && | |
526 | u[0] != '_') | |
527 | return false; | |
528 | ||
529 | for (i = u+1; *i; i++) { | |
530 | if (!(*i >= 'a' && *i <= 'z') && | |
531 | !(*i >= 'A' && *i <= 'Z') && | |
532 | !(*i >= '0' && *i <= '9') && | |
533 | *i != '_' && | |
534 | *i != '-') | |
535 | return false; | |
536 | } | |
537 | ||
538 | sz = sysconf(_SC_LOGIN_NAME_MAX); | |
539 | assert_se(sz > 0); | |
540 | ||
541 | if ((size_t) (i-u) > (size_t) sz) | |
542 | return false; | |
543 | ||
544 | if ((size_t) (i-u) > UT_NAMESIZE - 1) | |
545 | return false; | |
546 | ||
547 | return true; | |
548 | } | |
549 | ||
550 | bool valid_user_group_name_or_id(const char *u) { | |
551 | ||
552 | /* Similar as above, but is also fine with numeric UID/GID specifications, as long as they are in the right | |
553 | * range, and not the invalid user ids. */ | |
554 | ||
555 | if (isempty(u)) | |
556 | return false; | |
557 | ||
558 | if (valid_user_group_name(u)) | |
559 | return true; | |
560 | ||
561 | return parse_uid(u, NULL) >= 0; | |
562 | } | |
563 | ||
564 | bool valid_gecos(const char *d) { | |
565 | ||
566 | if (!d) | |
567 | return false; | |
568 | ||
569 | if (!utf8_is_valid(d)) | |
570 | return false; | |
571 | ||
572 | if (string_has_cc(d, NULL)) | |
573 | return false; | |
574 | ||
575 | /* Colons are used as field separators, and hence not OK */ | |
576 | if (strchr(d, ':')) | |
577 | return false; | |
578 | ||
579 | return true; | |
580 | } | |
581 | ||
582 | bool valid_home(const char *p) { | |
583 | ||
584 | if (isempty(p)) | |
585 | return false; | |
586 | ||
587 | if (!utf8_is_valid(p)) | |
588 | return false; | |
589 | ||
590 | if (string_has_cc(p, NULL)) | |
591 | return false; | |
592 | ||
593 | if (!path_is_absolute(p)) | |
594 | return false; | |
595 | ||
596 | if (!path_is_safe(p)) | |
597 | return false; | |
598 | ||
599 | /* Colons are used as field separators, and hence not OK */ | |
600 | if (strchr(p, ':')) | |
601 | return false; | |
602 | ||
603 | return true; | |
604 | } |