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Commit | Line | Data |
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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" |
36d85478 | 36 | #include "fileio.h" |
93cc7779 | 37 | #include "formats-util.h" |
b1d4f8e1 | 38 | #include "macro.h" |
be39ccf3 | 39 | #include "missing.h" |
6bedfcbb | 40 | #include "parse-util.h" |
b1d4f8e1 | 41 | #include "path-util.h" |
6bedfcbb | 42 | #include "string-util.h" |
be39ccf3 | 43 | #include "strv.h" |
6bedfcbb | 44 | #include "user-util.h" |
e4631b48 | 45 | #include "utf8.h" |
b1d4f8e1 LP |
46 | |
47 | bool uid_is_valid(uid_t uid) { | |
48 | ||
49 | /* Some libc APIs use UID_INVALID as special placeholder */ | |
b1d52773 | 50 | if (uid == (uid_t) UINT32_C(0xFFFFFFFF)) |
b1d4f8e1 LP |
51 | return false; |
52 | ||
53 | /* A long time ago UIDs where 16bit, hence explicitly avoid the 16bit -1 too */ | |
b1d52773 | 54 | if (uid == (uid_t) UINT32_C(0xFFFF)) |
b1d4f8e1 LP |
55 | return false; |
56 | ||
57 | return true; | |
58 | } | |
59 | ||
b1d52773 LP |
60 | int parse_uid(const char *s, uid_t *ret) { |
61 | uint32_t uid = 0; | |
b1d4f8e1 LP |
62 | int r; |
63 | ||
64 | assert(s); | |
65 | ||
b1d52773 LP |
66 | assert_cc(sizeof(uid_t) == sizeof(uint32_t)); |
67 | r = safe_atou32(s, &uid); | |
b1d4f8e1 LP |
68 | if (r < 0) |
69 | return r; | |
70 | ||
b1d4f8e1 LP |
71 | if (!uid_is_valid(uid)) |
72 | return -ENXIO; /* we return ENXIO instead of EINVAL | |
73 | * here, to make it easy to distuingish | |
ba60af86 | 74 | * invalid numeric uids from invalid |
b1d4f8e1 LP |
75 | * strings. */ |
76 | ||
b1d52773 LP |
77 | if (ret) |
78 | *ret = uid; | |
b1d4f8e1 LP |
79 | |
80 | return 0; | |
81 | } | |
82 | ||
b1d4f8e1 LP |
83 | char* getlogname_malloc(void) { |
84 | uid_t uid; | |
85 | struct stat st; | |
86 | ||
87 | if (isatty(STDIN_FILENO) && fstat(STDIN_FILENO, &st) >= 0) | |
88 | uid = st.st_uid; | |
89 | else | |
90 | uid = getuid(); | |
91 | ||
d0260817 | 92 | return uid_to_name(uid); |
b1d4f8e1 LP |
93 | } |
94 | ||
95 | char *getusername_malloc(void) { | |
96 | const char *e; | |
97 | ||
98 | e = getenv("USER"); | |
99 | if (e) | |
100 | return strdup(e); | |
101 | ||
d0260817 | 102 | return uid_to_name(getuid()); |
b1d4f8e1 LP |
103 | } |
104 | ||
105 | int get_user_creds( | |
106 | const char **username, | |
107 | uid_t *uid, gid_t *gid, | |
108 | const char **home, | |
109 | const char **shell) { | |
110 | ||
111 | struct passwd *p; | |
112 | uid_t u; | |
113 | ||
114 | assert(username); | |
115 | assert(*username); | |
116 | ||
117 | /* We enforce some special rules for uid=0: in order to avoid | |
118 | * NSS lookups for root we hardcode its data. */ | |
119 | ||
120 | if (streq(*username, "root") || streq(*username, "0")) { | |
121 | *username = "root"; | |
122 | ||
123 | if (uid) | |
124 | *uid = 0; | |
125 | ||
126 | if (gid) | |
127 | *gid = 0; | |
128 | ||
129 | if (home) | |
130 | *home = "/root"; | |
131 | ||
132 | if (shell) | |
133 | *shell = "/bin/sh"; | |
134 | ||
135 | return 0; | |
136 | } | |
137 | ||
138 | if (parse_uid(*username, &u) >= 0) { | |
139 | errno = 0; | |
140 | p = getpwuid(u); | |
141 | ||
142 | /* If there are multiple users with the same id, make | |
143 | * sure to leave $USER to the configured value instead | |
144 | * of the first occurrence in the database. However if | |
145 | * the uid was configured by a numeric uid, then let's | |
146 | * pick the real username from /etc/passwd. */ | |
147 | if (p) | |
148 | *username = p->pw_name; | |
149 | } else { | |
150 | errno = 0; | |
151 | p = getpwnam(*username); | |
152 | } | |
153 | ||
154 | if (!p) | |
155 | return errno > 0 ? -errno : -ESRCH; | |
156 | ||
67c7c892 LP |
157 | if (uid) { |
158 | if (!uid_is_valid(p->pw_uid)) | |
159 | return -EBADMSG; | |
160 | ||
b1d4f8e1 | 161 | *uid = p->pw_uid; |
67c7c892 LP |
162 | } |
163 | ||
164 | if (gid) { | |
165 | if (!gid_is_valid(p->pw_gid)) | |
166 | return -EBADMSG; | |
b1d4f8e1 | 167 | |
b1d4f8e1 | 168 | *gid = p->pw_gid; |
67c7c892 | 169 | } |
b1d4f8e1 LP |
170 | |
171 | if (home) | |
172 | *home = p->pw_dir; | |
173 | ||
174 | if (shell) | |
175 | *shell = p->pw_shell; | |
176 | ||
177 | return 0; | |
178 | } | |
179 | ||
be39ccf3 LP |
180 | int get_user_creds_clean( |
181 | const char **username, | |
182 | uid_t *uid, gid_t *gid, | |
183 | const char **home, | |
184 | const char **shell) { | |
185 | ||
186 | int r; | |
187 | ||
188 | /* Like get_user_creds(), but resets home/shell to NULL if they don't contain anything relevant. */ | |
189 | ||
190 | r = get_user_creds(username, uid, gid, home, shell); | |
191 | if (r < 0) | |
192 | return r; | |
193 | ||
194 | if (shell && | |
195 | (isempty(*shell) || PATH_IN_SET(*shell, | |
196 | "/bin/nologin", | |
197 | "/sbin/nologin", | |
198 | "/usr/bin/nologin", | |
199 | "/usr/sbin/nologin"))) | |
200 | *shell = NULL; | |
201 | ||
202 | if (home && | |
203 | (isempty(*home) || path_equal(*home, "/"))) | |
204 | *home = NULL; | |
205 | ||
206 | return 0; | |
207 | } | |
208 | ||
b1d4f8e1 LP |
209 | int get_group_creds(const char **groupname, gid_t *gid) { |
210 | struct group *g; | |
211 | gid_t id; | |
212 | ||
213 | assert(groupname); | |
214 | ||
215 | /* We enforce some special rules for gid=0: in order to avoid | |
216 | * NSS lookups for root we hardcode its data. */ | |
217 | ||
218 | if (streq(*groupname, "root") || streq(*groupname, "0")) { | |
219 | *groupname = "root"; | |
220 | ||
221 | if (gid) | |
222 | *gid = 0; | |
223 | ||
224 | return 0; | |
225 | } | |
226 | ||
227 | if (parse_gid(*groupname, &id) >= 0) { | |
228 | errno = 0; | |
229 | g = getgrgid(id); | |
230 | ||
231 | if (g) | |
232 | *groupname = g->gr_name; | |
233 | } else { | |
234 | errno = 0; | |
235 | g = getgrnam(*groupname); | |
236 | } | |
237 | ||
238 | if (!g) | |
239 | return errno > 0 ? -errno : -ESRCH; | |
240 | ||
67c7c892 LP |
241 | if (gid) { |
242 | if (!gid_is_valid(g->gr_gid)) | |
243 | return -EBADMSG; | |
244 | ||
b1d4f8e1 | 245 | *gid = g->gr_gid; |
67c7c892 | 246 | } |
b1d4f8e1 LP |
247 | |
248 | return 0; | |
249 | } | |
250 | ||
251 | char* uid_to_name(uid_t uid) { | |
d0260817 LP |
252 | char *ret; |
253 | int r; | |
b1d4f8e1 | 254 | |
d0260817 | 255 | /* Shortcut things to avoid NSS lookups */ |
b1d4f8e1 LP |
256 | if (uid == 0) |
257 | return strdup("root"); | |
258 | ||
d0260817 LP |
259 | if (uid_is_valid(uid)) { |
260 | long bufsize; | |
261 | ||
262 | bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); | |
263 | if (bufsize <= 0) | |
264 | bufsize = 4096; | |
265 | ||
266 | for (;;) { | |
267 | struct passwd pwbuf, *pw = NULL; | |
268 | _cleanup_free_ char *buf = NULL; | |
269 | ||
270 | buf = malloc(bufsize); | |
271 | if (!buf) | |
272 | return NULL; | |
273 | ||
274 | r = getpwuid_r(uid, &pwbuf, buf, (size_t) bufsize, &pw); | |
275 | if (r == 0 && pw) | |
276 | return strdup(pw->pw_name); | |
277 | if (r != ERANGE) | |
278 | break; | |
279 | ||
280 | bufsize *= 2; | |
281 | } | |
282 | } | |
b1d4f8e1 | 283 | |
d0260817 | 284 | if (asprintf(&ret, UID_FMT, uid) < 0) |
b1d4f8e1 LP |
285 | return NULL; |
286 | ||
d0260817 | 287 | return ret; |
b1d4f8e1 LP |
288 | } |
289 | ||
290 | char* gid_to_name(gid_t gid) { | |
d0260817 LP |
291 | char *ret; |
292 | int r; | |
b1d4f8e1 LP |
293 | |
294 | if (gid == 0) | |
295 | return strdup("root"); | |
296 | ||
d0260817 LP |
297 | if (gid_is_valid(gid)) { |
298 | long bufsize; | |
299 | ||
300 | bufsize = sysconf(_SC_GETGR_R_SIZE_MAX); | |
301 | if (bufsize <= 0) | |
302 | bufsize = 4096; | |
303 | ||
304 | for (;;) { | |
305 | struct group grbuf, *gr = NULL; | |
306 | _cleanup_free_ char *buf = NULL; | |
307 | ||
308 | buf = malloc(bufsize); | |
309 | if (!buf) | |
310 | return NULL; | |
311 | ||
312 | r = getgrgid_r(gid, &grbuf, buf, (size_t) bufsize, &gr); | |
313 | if (r == 0 && gr) | |
314 | return strdup(gr->gr_name); | |
315 | if (r != ERANGE) | |
316 | break; | |
317 | ||
318 | bufsize *= 2; | |
319 | } | |
320 | } | |
b1d4f8e1 | 321 | |
d0260817 | 322 | if (asprintf(&ret, GID_FMT, gid) < 0) |
b1d4f8e1 LP |
323 | return NULL; |
324 | ||
d0260817 | 325 | return ret; |
b1d4f8e1 LP |
326 | } |
327 | ||
328 | int in_gid(gid_t gid) { | |
329 | gid_t *gids; | |
330 | int ngroups_max, r, i; | |
331 | ||
332 | if (getgid() == gid) | |
333 | return 1; | |
334 | ||
335 | if (getegid() == gid) | |
336 | return 1; | |
337 | ||
67c7c892 LP |
338 | if (!gid_is_valid(gid)) |
339 | return -EINVAL; | |
340 | ||
b1d4f8e1 LP |
341 | ngroups_max = sysconf(_SC_NGROUPS_MAX); |
342 | assert(ngroups_max > 0); | |
343 | ||
344 | gids = alloca(sizeof(gid_t) * ngroups_max); | |
345 | ||
346 | r = getgroups(ngroups_max, gids); | |
347 | if (r < 0) | |
348 | return -errno; | |
349 | ||
350 | for (i = 0; i < r; i++) | |
351 | if (gids[i] == gid) | |
352 | return 1; | |
353 | ||
354 | return 0; | |
355 | } | |
356 | ||
357 | int in_group(const char *name) { | |
358 | int r; | |
359 | gid_t gid; | |
360 | ||
361 | r = get_group_creds(&name, &gid); | |
362 | if (r < 0) | |
363 | return r; | |
364 | ||
365 | return in_gid(gid); | |
366 | } | |
367 | ||
368 | int get_home_dir(char **_h) { | |
369 | struct passwd *p; | |
370 | const char *e; | |
371 | char *h; | |
372 | uid_t u; | |
373 | ||
374 | assert(_h); | |
375 | ||
376 | /* Take the user specified one */ | |
377 | e = secure_getenv("HOME"); | |
378 | if (e && path_is_absolute(e)) { | |
379 | h = strdup(e); | |
380 | if (!h) | |
381 | return -ENOMEM; | |
382 | ||
383 | *_h = h; | |
384 | return 0; | |
385 | } | |
386 | ||
387 | /* Hardcode home directory for root to avoid NSS */ | |
388 | u = getuid(); | |
389 | if (u == 0) { | |
390 | h = strdup("/root"); | |
391 | if (!h) | |
392 | return -ENOMEM; | |
393 | ||
394 | *_h = h; | |
395 | return 0; | |
396 | } | |
397 | ||
398 | /* Check the database... */ | |
399 | errno = 0; | |
400 | p = getpwuid(u); | |
401 | if (!p) | |
402 | return errno > 0 ? -errno : -ESRCH; | |
403 | ||
404 | if (!path_is_absolute(p->pw_dir)) | |
405 | return -EINVAL; | |
406 | ||
407 | h = strdup(p->pw_dir); | |
408 | if (!h) | |
409 | return -ENOMEM; | |
410 | ||
411 | *_h = h; | |
412 | return 0; | |
413 | } | |
414 | ||
415 | int get_shell(char **_s) { | |
416 | struct passwd *p; | |
417 | const char *e; | |
418 | char *s; | |
419 | uid_t u; | |
420 | ||
421 | assert(_s); | |
422 | ||
423 | /* Take the user specified one */ | |
424 | e = getenv("SHELL"); | |
425 | if (e) { | |
426 | s = strdup(e); | |
427 | if (!s) | |
428 | return -ENOMEM; | |
429 | ||
430 | *_s = s; | |
431 | return 0; | |
432 | } | |
433 | ||
434 | /* Hardcode home directory for root to avoid NSS */ | |
435 | u = getuid(); | |
436 | if (u == 0) { | |
437 | s = strdup("/bin/sh"); | |
438 | if (!s) | |
439 | return -ENOMEM; | |
440 | ||
441 | *_s = s; | |
442 | return 0; | |
443 | } | |
444 | ||
445 | /* Check the database... */ | |
446 | errno = 0; | |
447 | p = getpwuid(u); | |
448 | if (!p) | |
449 | return errno > 0 ? -errno : -ESRCH; | |
450 | ||
451 | if (!path_is_absolute(p->pw_shell)) | |
452 | return -EINVAL; | |
453 | ||
454 | s = strdup(p->pw_shell); | |
455 | if (!s) | |
456 | return -ENOMEM; | |
457 | ||
458 | *_s = s; | |
459 | return 0; | |
460 | } | |
461 | ||
462 | int reset_uid_gid(void) { | |
463 | ||
36d85478 | 464 | if (maybe_setgroups(0, NULL) < 0) |
b1d4f8e1 LP |
465 | return -errno; |
466 | ||
467 | if (setresgid(0, 0, 0) < 0) | |
468 | return -errno; | |
469 | ||
470 | if (setresuid(0, 0, 0) < 0) | |
471 | return -errno; | |
472 | ||
473 | return 0; | |
474 | } | |
e929bee0 LP |
475 | |
476 | int take_etc_passwd_lock(const char *root) { | |
477 | ||
478 | struct flock flock = { | |
479 | .l_type = F_WRLCK, | |
480 | .l_whence = SEEK_SET, | |
481 | .l_start = 0, | |
482 | .l_len = 0, | |
483 | }; | |
484 | ||
485 | const char *path; | |
486 | int fd, r; | |
487 | ||
488 | /* This is roughly the same as lckpwdf(), but not as awful. We | |
489 | * don't want to use alarm() and signals, hence we implement | |
490 | * our own trivial version of this. | |
491 | * | |
492 | * Note that shadow-utils also takes per-database locks in | |
493 | * addition to lckpwdf(). However, we don't given that they | |
61233823 | 494 | * are redundant as they invoke lckpwdf() first and keep |
e929bee0 LP |
495 | * it during everything they do. The per-database locks are |
496 | * awfully racy, and thus we just won't do them. */ | |
497 | ||
498 | if (root) | |
499 | path = prefix_roota(root, "/etc/.pwd.lock"); | |
500 | else | |
501 | path = "/etc/.pwd.lock"; | |
502 | ||
503 | fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0600); | |
504 | if (fd < 0) | |
505 | return -errno; | |
506 | ||
507 | r = fcntl(fd, F_SETLKW, &flock); | |
508 | if (r < 0) { | |
509 | safe_close(fd); | |
510 | return -errno; | |
511 | } | |
512 | ||
513 | return fd; | |
514 | } | |
e4631b48 LP |
515 | |
516 | bool valid_user_group_name(const char *u) { | |
517 | const char *i; | |
518 | long sz; | |
519 | ||
520 | /* Checks if the specified name is a valid user/group name. */ | |
521 | ||
522 | if (isempty(u)) | |
523 | return false; | |
524 | ||
525 | if (!(u[0] >= 'a' && u[0] <= 'z') && | |
526 | !(u[0] >= 'A' && u[0] <= 'Z') && | |
527 | u[0] != '_') | |
528 | return false; | |
529 | ||
530 | for (i = u+1; *i; i++) { | |
531 | if (!(*i >= 'a' && *i <= 'z') && | |
532 | !(*i >= 'A' && *i <= 'Z') && | |
533 | !(*i >= '0' && *i <= '9') && | |
534 | *i != '_' && | |
535 | *i != '-') | |
536 | return false; | |
537 | } | |
538 | ||
539 | sz = sysconf(_SC_LOGIN_NAME_MAX); | |
540 | assert_se(sz > 0); | |
541 | ||
542 | if ((size_t) (i-u) > (size_t) sz) | |
543 | return false; | |
544 | ||
545 | if ((size_t) (i-u) > UT_NAMESIZE - 1) | |
546 | return false; | |
547 | ||
548 | return true; | |
549 | } | |
550 | ||
551 | bool valid_user_group_name_or_id(const char *u) { | |
552 | ||
553 | /* Similar as above, but is also fine with numeric UID/GID specifications, as long as they are in the right | |
554 | * range, and not the invalid user ids. */ | |
555 | ||
556 | if (isempty(u)) | |
557 | return false; | |
558 | ||
559 | if (valid_user_group_name(u)) | |
560 | return true; | |
561 | ||
562 | return parse_uid(u, NULL) >= 0; | |
563 | } | |
564 | ||
565 | bool valid_gecos(const char *d) { | |
566 | ||
567 | if (!d) | |
568 | return false; | |
569 | ||
570 | if (!utf8_is_valid(d)) | |
571 | return false; | |
572 | ||
573 | if (string_has_cc(d, NULL)) | |
574 | return false; | |
575 | ||
576 | /* Colons are used as field separators, and hence not OK */ | |
577 | if (strchr(d, ':')) | |
578 | return false; | |
579 | ||
580 | return true; | |
581 | } | |
582 | ||
583 | bool valid_home(const char *p) { | |
584 | ||
585 | if (isempty(p)) | |
586 | return false; | |
587 | ||
588 | if (!utf8_is_valid(p)) | |
589 | return false; | |
590 | ||
591 | if (string_has_cc(p, NULL)) | |
592 | return false; | |
593 | ||
594 | if (!path_is_absolute(p)) | |
595 | return false; | |
596 | ||
597 | if (!path_is_safe(p)) | |
598 | return false; | |
599 | ||
600 | /* Colons are used as field separators, and hence not OK */ | |
601 | if (strchr(p, ':')) | |
602 | return false; | |
603 | ||
604 | return true; | |
605 | } | |
36d85478 GS |
606 | |
607 | int maybe_setgroups(size_t size, const gid_t *list) { | |
608 | static int cached_can_setgroups = -1; | |
609 | /* check if setgroups is allowed before we try to drop all the auxiliary groups */ | |
610 | if (size == 0) { | |
611 | if (cached_can_setgroups < 0) { | |
612 | _cleanup_free_ char *setgroups_content = NULL; | |
613 | int r = read_one_line_file("/proc/self/setgroups", &setgroups_content); | |
614 | if (r < 0 && errno != ENOENT) | |
615 | return r; | |
616 | if (r < 0) { | |
617 | /* old kernels don't have /proc/self/setgroups, so assume we can use setgroups */ | |
618 | cached_can_setgroups = true; | |
619 | } else { | |
620 | cached_can_setgroups = streq(setgroups_content, "allow"); | |
621 | if (!cached_can_setgroups) | |
622 | log_debug("skip setgroups, /proc/self/setgroups is set to 'deny'"); | |
623 | } | |
624 | } | |
625 | if (!cached_can_setgroups) | |
626 | return 0; | |
627 | } | |
628 | return setgroups(size, list); | |
629 | } |