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Commit | Line | Data |
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f4f15635 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 <errno.h> |
21 | #include <stddef.h> | |
22 | #include <stdio.h> | |
23 | #include <stdlib.h> | |
24 | #include <string.h> | |
25 | #include <sys/stat.h> | |
655f2da0 | 26 | #include <linux/magic.h> |
11c3a366 TA |
27 | #include <time.h> |
28 | #include <unistd.h> | |
29 | ||
b5efdb8a | 30 | #include "alloc-util.h" |
f4f15635 LP |
31 | #include "dirent-util.h" |
32 | #include "fd-util.h" | |
33 | #include "fileio.h" | |
34 | #include "fs-util.h" | |
11c3a366 TA |
35 | #include "log.h" |
36 | #include "macro.h" | |
37 | #include "missing.h" | |
93cc7779 TA |
38 | #include "mkdir.h" |
39 | #include "parse-util.h" | |
40 | #include "path-util.h" | |
34a8f081 | 41 | #include "stat-util.h" |
430fbf8e | 42 | #include "stdio-util.h" |
f4f15635 LP |
43 | #include "string-util.h" |
44 | #include "strv.h" | |
93cc7779 | 45 | #include "time-util.h" |
ee104e11 | 46 | #include "user-util.h" |
f4f15635 LP |
47 | #include "util.h" |
48 | ||
49 | int unlink_noerrno(const char *path) { | |
50 | PROTECT_ERRNO; | |
51 | int r; | |
52 | ||
53 | r = unlink(path); | |
54 | if (r < 0) | |
55 | return -errno; | |
56 | ||
57 | return 0; | |
58 | } | |
59 | ||
60 | int rmdir_parents(const char *path, const char *stop) { | |
61 | size_t l; | |
62 | int r = 0; | |
63 | ||
64 | assert(path); | |
65 | assert(stop); | |
66 | ||
67 | l = strlen(path); | |
68 | ||
69 | /* Skip trailing slashes */ | |
70 | while (l > 0 && path[l-1] == '/') | |
71 | l--; | |
72 | ||
73 | while (l > 0) { | |
74 | char *t; | |
75 | ||
76 | /* Skip last component */ | |
77 | while (l > 0 && path[l-1] != '/') | |
78 | l--; | |
79 | ||
80 | /* Skip trailing slashes */ | |
81 | while (l > 0 && path[l-1] == '/') | |
82 | l--; | |
83 | ||
84 | if (l <= 0) | |
85 | break; | |
86 | ||
87 | t = strndup(path, l); | |
88 | if (!t) | |
89 | return -ENOMEM; | |
90 | ||
91 | if (path_startswith(stop, t)) { | |
92 | free(t); | |
93 | return 0; | |
94 | } | |
95 | ||
96 | r = rmdir(t); | |
97 | free(t); | |
98 | ||
99 | if (r < 0) | |
100 | if (errno != ENOENT) | |
101 | return -errno; | |
102 | } | |
103 | ||
104 | return 0; | |
105 | } | |
106 | ||
107 | ||
108 | int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath) { | |
109 | struct stat buf; | |
110 | int ret; | |
111 | ||
112 | ret = renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE); | |
113 | if (ret >= 0) | |
114 | return 0; | |
115 | ||
116 | /* renameat2() exists since Linux 3.15, btrfs added support for it later. | |
117 | * If it is not implemented, fallback to another method. */ | |
118 | if (!IN_SET(errno, EINVAL, ENOSYS)) | |
119 | return -errno; | |
120 | ||
121 | /* The link()/unlink() fallback does not work on directories. But | |
122 | * renameat() without RENAME_NOREPLACE gives the same semantics on | |
123 | * directories, except when newpath is an *empty* directory. This is | |
124 | * good enough. */ | |
125 | ret = fstatat(olddirfd, oldpath, &buf, AT_SYMLINK_NOFOLLOW); | |
126 | if (ret >= 0 && S_ISDIR(buf.st_mode)) { | |
127 | ret = renameat(olddirfd, oldpath, newdirfd, newpath); | |
128 | return ret >= 0 ? 0 : -errno; | |
129 | } | |
130 | ||
131 | /* If it is not a directory, use the link()/unlink() fallback. */ | |
132 | ret = linkat(olddirfd, oldpath, newdirfd, newpath, 0); | |
133 | if (ret < 0) | |
134 | return -errno; | |
135 | ||
136 | ret = unlinkat(olddirfd, oldpath, 0); | |
137 | if (ret < 0) { | |
138 | /* backup errno before the following unlinkat() alters it */ | |
139 | ret = errno; | |
140 | (void) unlinkat(newdirfd, newpath, 0); | |
141 | errno = ret; | |
142 | return -errno; | |
143 | } | |
144 | ||
145 | return 0; | |
146 | } | |
147 | ||
148 | int readlinkat_malloc(int fd, const char *p, char **ret) { | |
149 | size_t l = 100; | |
150 | int r; | |
151 | ||
152 | assert(p); | |
153 | assert(ret); | |
154 | ||
155 | for (;;) { | |
156 | char *c; | |
157 | ssize_t n; | |
158 | ||
159 | c = new(char, l); | |
160 | if (!c) | |
161 | return -ENOMEM; | |
162 | ||
163 | n = readlinkat(fd, p, c, l-1); | |
164 | if (n < 0) { | |
165 | r = -errno; | |
166 | free(c); | |
167 | return r; | |
168 | } | |
169 | ||
170 | if ((size_t) n < l-1) { | |
171 | c[n] = 0; | |
172 | *ret = c; | |
173 | return 0; | |
174 | } | |
175 | ||
176 | free(c); | |
177 | l *= 2; | |
178 | } | |
179 | } | |
180 | ||
181 | int readlink_malloc(const char *p, char **ret) { | |
182 | return readlinkat_malloc(AT_FDCWD, p, ret); | |
183 | } | |
184 | ||
185 | int readlink_value(const char *p, char **ret) { | |
186 | _cleanup_free_ char *link = NULL; | |
187 | char *value; | |
188 | int r; | |
189 | ||
190 | r = readlink_malloc(p, &link); | |
191 | if (r < 0) | |
192 | return r; | |
193 | ||
194 | value = basename(link); | |
195 | if (!value) | |
196 | return -ENOENT; | |
197 | ||
198 | value = strdup(value); | |
199 | if (!value) | |
200 | return -ENOMEM; | |
201 | ||
202 | *ret = value; | |
203 | ||
204 | return 0; | |
205 | } | |
206 | ||
207 | int readlink_and_make_absolute(const char *p, char **r) { | |
208 | _cleanup_free_ char *target = NULL; | |
209 | char *k; | |
210 | int j; | |
211 | ||
212 | assert(p); | |
213 | assert(r); | |
214 | ||
215 | j = readlink_malloc(p, &target); | |
216 | if (j < 0) | |
217 | return j; | |
218 | ||
219 | k = file_in_same_dir(p, target); | |
220 | if (!k) | |
221 | return -ENOMEM; | |
222 | ||
223 | *r = k; | |
224 | return 0; | |
225 | } | |
226 | ||
e1873695 | 227 | int readlink_and_canonicalize(const char *p, const char *root, char **ret) { |
f4f15635 | 228 | char *t, *s; |
e1873695 | 229 | int r; |
f4f15635 LP |
230 | |
231 | assert(p); | |
e1873695 | 232 | assert(ret); |
f4f15635 | 233 | |
e1873695 LP |
234 | r = readlink_and_make_absolute(p, &t); |
235 | if (r < 0) | |
236 | return r; | |
f4f15635 | 237 | |
c4f4fce7 | 238 | r = chase_symlinks(t, root, 0, &s); |
e1873695 LP |
239 | if (r < 0) |
240 | /* If we can't follow up, then let's return the original string, slightly cleaned up. */ | |
241 | *ret = path_kill_slashes(t); | |
242 | else { | |
243 | *ret = s; | |
f4f15635 | 244 | free(t); |
e1873695 | 245 | } |
f4f15635 LP |
246 | |
247 | return 0; | |
248 | } | |
249 | ||
0ec0deaa LP |
250 | int readlink_and_make_absolute_root(const char *root, const char *path, char **ret) { |
251 | _cleanup_free_ char *target = NULL, *t = NULL; | |
252 | const char *full; | |
253 | int r; | |
254 | ||
255 | full = prefix_roota(root, path); | |
256 | r = readlink_malloc(full, &target); | |
257 | if (r < 0) | |
258 | return r; | |
259 | ||
260 | t = file_in_same_dir(path, target); | |
261 | if (!t) | |
262 | return -ENOMEM; | |
263 | ||
264 | *ret = t; | |
265 | t = NULL; | |
266 | ||
267 | return 0; | |
268 | } | |
269 | ||
f4f15635 LP |
270 | int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid) { |
271 | assert(path); | |
272 | ||
273 | /* Under the assumption that we are running privileged we | |
274 | * first change the access mode and only then hand out | |
275 | * ownership to avoid a window where access is too open. */ | |
276 | ||
277 | if (mode != MODE_INVALID) | |
278 | if (chmod(path, mode) < 0) | |
279 | return -errno; | |
280 | ||
281 | if (uid != UID_INVALID || gid != GID_INVALID) | |
282 | if (chown(path, uid, gid) < 0) | |
283 | return -errno; | |
284 | ||
285 | return 0; | |
286 | } | |
287 | ||
f4f15635 LP |
288 | int fchmod_umask(int fd, mode_t m) { |
289 | mode_t u; | |
290 | int r; | |
291 | ||
292 | u = umask(0777); | |
293 | r = fchmod(fd, m & (~u)) < 0 ? -errno : 0; | |
294 | umask(u); | |
295 | ||
296 | return r; | |
297 | } | |
298 | ||
299 | int fd_warn_permissions(const char *path, int fd) { | |
300 | struct stat st; | |
301 | ||
302 | if (fstat(fd, &st) < 0) | |
303 | return -errno; | |
304 | ||
305 | if (st.st_mode & 0111) | |
306 | log_warning("Configuration file %s is marked executable. Please remove executable permission bits. Proceeding anyway.", path); | |
307 | ||
308 | if (st.st_mode & 0002) | |
309 | log_warning("Configuration file %s is marked world-writable. Please remove world writability permission bits. Proceeding anyway.", path); | |
310 | ||
df0ff127 | 311 | if (getpid_cached() == 1 && (st.st_mode & 0044) != 0044) |
f4f15635 LP |
312 | log_warning("Configuration file %s is marked world-inaccessible. This has no effect as configuration data is accessible via APIs without restrictions. Proceeding anyway.", path); |
313 | ||
314 | return 0; | |
315 | } | |
316 | ||
317 | int touch_file(const char *path, bool parents, usec_t stamp, uid_t uid, gid_t gid, mode_t mode) { | |
318 | _cleanup_close_ int fd; | |
319 | int r; | |
320 | ||
321 | assert(path); | |
322 | ||
323 | if (parents) | |
324 | mkdir_parents(path, 0755); | |
325 | ||
06eeacb6 | 326 | fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, |
4c701096 | 327 | IN_SET(mode, 0, MODE_INVALID) ? 0644 : mode); |
f4f15635 LP |
328 | if (fd < 0) |
329 | return -errno; | |
330 | ||
ee735086 | 331 | if (mode != MODE_INVALID) { |
f4f15635 LP |
332 | r = fchmod(fd, mode); |
333 | if (r < 0) | |
334 | return -errno; | |
335 | } | |
336 | ||
337 | if (uid != UID_INVALID || gid != GID_INVALID) { | |
338 | r = fchown(fd, uid, gid); | |
339 | if (r < 0) | |
340 | return -errno; | |
341 | } | |
342 | ||
343 | if (stamp != USEC_INFINITY) { | |
344 | struct timespec ts[2]; | |
345 | ||
346 | timespec_store(&ts[0], stamp); | |
347 | ts[1] = ts[0]; | |
348 | r = futimens(fd, ts); | |
349 | } else | |
350 | r = futimens(fd, NULL); | |
351 | if (r < 0) | |
352 | return -errno; | |
353 | ||
354 | return 0; | |
355 | } | |
356 | ||
357 | int touch(const char *path) { | |
ee735086 | 358 | return touch_file(path, false, USEC_INFINITY, UID_INVALID, GID_INVALID, MODE_INVALID); |
f4f15635 LP |
359 | } |
360 | ||
361 | int symlink_idempotent(const char *from, const char *to) { | |
f4f15635 LP |
362 | int r; |
363 | ||
364 | assert(from); | |
365 | assert(to); | |
366 | ||
367 | if (symlink(from, to) < 0) { | |
77b79723 LP |
368 | _cleanup_free_ char *p = NULL; |
369 | ||
f4f15635 LP |
370 | if (errno != EEXIST) |
371 | return -errno; | |
372 | ||
373 | r = readlink_malloc(to, &p); | |
77b79723 LP |
374 | if (r == -EINVAL) /* Not a symlink? In that case return the original error we encountered: -EEXIST */ |
375 | return -EEXIST; | |
376 | if (r < 0) /* Any other error? In that case propagate it as is */ | |
f4f15635 LP |
377 | return r; |
378 | ||
77b79723 LP |
379 | if (!streq(p, from)) /* Not the symlink we want it to be? In that case, propagate the original -EEXIST */ |
380 | return -EEXIST; | |
f4f15635 LP |
381 | } |
382 | ||
383 | return 0; | |
384 | } | |
385 | ||
386 | int symlink_atomic(const char *from, const char *to) { | |
387 | _cleanup_free_ char *t = NULL; | |
388 | int r; | |
389 | ||
390 | assert(from); | |
391 | assert(to); | |
392 | ||
393 | r = tempfn_random(to, NULL, &t); | |
394 | if (r < 0) | |
395 | return r; | |
396 | ||
397 | if (symlink(from, t) < 0) | |
398 | return -errno; | |
399 | ||
400 | if (rename(t, to) < 0) { | |
401 | unlink_noerrno(t); | |
402 | return -errno; | |
403 | } | |
404 | ||
405 | return 0; | |
406 | } | |
407 | ||
408 | int mknod_atomic(const char *path, mode_t mode, dev_t dev) { | |
409 | _cleanup_free_ char *t = NULL; | |
410 | int r; | |
411 | ||
412 | assert(path); | |
413 | ||
414 | r = tempfn_random(path, NULL, &t); | |
415 | if (r < 0) | |
416 | return r; | |
417 | ||
418 | if (mknod(t, mode, dev) < 0) | |
419 | return -errno; | |
420 | ||
421 | if (rename(t, path) < 0) { | |
422 | unlink_noerrno(t); | |
423 | return -errno; | |
424 | } | |
425 | ||
426 | return 0; | |
427 | } | |
428 | ||
429 | int mkfifo_atomic(const char *path, mode_t mode) { | |
430 | _cleanup_free_ char *t = NULL; | |
431 | int r; | |
432 | ||
433 | assert(path); | |
434 | ||
435 | r = tempfn_random(path, NULL, &t); | |
436 | if (r < 0) | |
437 | return r; | |
438 | ||
439 | if (mkfifo(t, mode) < 0) | |
440 | return -errno; | |
441 | ||
442 | if (rename(t, path) < 0) { | |
443 | unlink_noerrno(t); | |
444 | return -errno; | |
445 | } | |
446 | ||
447 | return 0; | |
448 | } | |
449 | ||
450 | int get_files_in_directory(const char *path, char ***list) { | |
451 | _cleanup_closedir_ DIR *d = NULL; | |
8fb3f009 | 452 | struct dirent *de; |
f4f15635 LP |
453 | size_t bufsize = 0, n = 0; |
454 | _cleanup_strv_free_ char **l = NULL; | |
455 | ||
456 | assert(path); | |
457 | ||
458 | /* Returns all files in a directory in *list, and the number | |
459 | * of files as return value. If list is NULL returns only the | |
460 | * number. */ | |
461 | ||
462 | d = opendir(path); | |
463 | if (!d) | |
464 | return -errno; | |
465 | ||
8fb3f009 | 466 | FOREACH_DIRENT_ALL(de, d, return -errno) { |
f4f15635 LP |
467 | dirent_ensure_type(d, de); |
468 | ||
469 | if (!dirent_is_file(de)) | |
470 | continue; | |
471 | ||
472 | if (list) { | |
473 | /* one extra slot is needed for the terminating NULL */ | |
474 | if (!GREEDY_REALLOC(l, bufsize, n + 2)) | |
475 | return -ENOMEM; | |
476 | ||
477 | l[n] = strdup(de->d_name); | |
478 | if (!l[n]) | |
479 | return -ENOMEM; | |
480 | ||
481 | l[++n] = NULL; | |
482 | } else | |
483 | n++; | |
484 | } | |
485 | ||
486 | if (list) { | |
487 | *list = l; | |
488 | l = NULL; /* avoid freeing */ | |
489 | } | |
490 | ||
491 | return n; | |
492 | } | |
430fbf8e | 493 | |
992e8f22 LP |
494 | static int getenv_tmp_dir(const char **ret_path) { |
495 | const char *n; | |
496 | int r, ret = 0; | |
34a8f081 | 497 | |
992e8f22 | 498 | assert(ret_path); |
34a8f081 | 499 | |
992e8f22 LP |
500 | /* We use the same order of environment variables python uses in tempfile.gettempdir(): |
501 | * https://docs.python.org/3/library/tempfile.html#tempfile.gettempdir */ | |
502 | FOREACH_STRING(n, "TMPDIR", "TEMP", "TMP") { | |
503 | const char *e; | |
504 | ||
505 | e = secure_getenv(n); | |
506 | if (!e) | |
507 | continue; | |
508 | if (!path_is_absolute(e)) { | |
509 | r = -ENOTDIR; | |
510 | goto next; | |
511 | } | |
512 | if (!path_is_safe(e)) { | |
513 | r = -EPERM; | |
514 | goto next; | |
515 | } | |
516 | ||
517 | r = is_dir(e, true); | |
518 | if (r < 0) | |
519 | goto next; | |
520 | if (r == 0) { | |
521 | r = -ENOTDIR; | |
522 | goto next; | |
523 | } | |
524 | ||
525 | *ret_path = e; | |
526 | return 1; | |
527 | ||
528 | next: | |
529 | /* Remember first error, to make this more debuggable */ | |
530 | if (ret >= 0) | |
531 | ret = r; | |
34a8f081 OW |
532 | } |
533 | ||
992e8f22 LP |
534 | if (ret < 0) |
535 | return ret; | |
34a8f081 | 536 | |
992e8f22 LP |
537 | *ret_path = NULL; |
538 | return ret; | |
539 | } | |
34a8f081 | 540 | |
992e8f22 LP |
541 | static int tmp_dir_internal(const char *def, const char **ret) { |
542 | const char *e; | |
543 | int r, k; | |
544 | ||
545 | assert(def); | |
546 | assert(ret); | |
547 | ||
548 | r = getenv_tmp_dir(&e); | |
549 | if (r > 0) { | |
550 | *ret = e; | |
551 | return 0; | |
552 | } | |
553 | ||
554 | k = is_dir(def, true); | |
555 | if (k == 0) | |
556 | k = -ENOTDIR; | |
557 | if (k < 0) | |
558 | return r < 0 ? r : k; | |
559 | ||
560 | *ret = def; | |
34a8f081 OW |
561 | return 0; |
562 | } | |
563 | ||
992e8f22 LP |
564 | int var_tmp_dir(const char **ret) { |
565 | ||
566 | /* Returns the location for "larger" temporary files, that is backed by physical storage if available, and thus | |
567 | * even might survive a boot: /var/tmp. If $TMPDIR (or related environment variables) are set, its value is | |
568 | * returned preferably however. Note that both this function and tmp_dir() below are affected by $TMPDIR, | |
569 | * making it a variable that overrides all temporary file storage locations. */ | |
570 | ||
571 | return tmp_dir_internal("/var/tmp", ret); | |
572 | } | |
573 | ||
574 | int tmp_dir(const char **ret) { | |
575 | ||
576 | /* Similar to var_tmp_dir() above, but returns the location for "smaller" temporary files, which is usually | |
577 | * backed by an in-memory file system: /tmp. */ | |
578 | ||
579 | return tmp_dir_internal("/tmp", ret); | |
580 | } | |
581 | ||
430fbf8e LP |
582 | int inotify_add_watch_fd(int fd, int what, uint32_t mask) { |
583 | char path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1]; | |
584 | int r; | |
585 | ||
586 | /* This is like inotify_add_watch(), except that the file to watch is not referenced by a path, but by an fd */ | |
587 | xsprintf(path, "/proc/self/fd/%i", what); | |
588 | ||
589 | r = inotify_add_watch(fd, path, mask); | |
590 | if (r < 0) | |
591 | return -errno; | |
592 | ||
593 | return r; | |
594 | } | |
d944dc95 | 595 | |
c4f4fce7 | 596 | int chase_symlinks(const char *path, const char *original_root, unsigned flags, char **ret) { |
d944dc95 LP |
597 | _cleanup_free_ char *buffer = NULL, *done = NULL, *root = NULL; |
598 | _cleanup_close_ int fd = -1; | |
599 | unsigned max_follow = 32; /* how many symlinks to follow before giving up and returning ELOOP */ | |
a9fb0867 | 600 | bool exists = true; |
d944dc95 LP |
601 | char *todo; |
602 | int r; | |
603 | ||
604 | assert(path); | |
605 | ||
606 | /* This is a lot like canonicalize_file_name(), but takes an additional "root" parameter, that allows following | |
607 | * symlinks relative to a root directory, instead of the root of the host. | |
608 | * | |
fc4b68e5 | 609 | * Note that "root" primarily matters if we encounter an absolute symlink. It is also used when following |
c4f4fce7 LP |
610 | * relative symlinks to ensure they cannot be used to "escape" the root directory. The path parameter passed is |
611 | * assumed to be already prefixed by it, except if the CHASE_PREFIX_ROOT flag is set, in which case it is first | |
612 | * prefixed accordingly. | |
d944dc95 LP |
613 | * |
614 | * Algorithmically this operates on two path buffers: "done" are the components of the path we already | |
615 | * processed and resolved symlinks, "." and ".." of. "todo" are the components of the path we still need to | |
616 | * process. On each iteration, we move one component from "todo" to "done", processing it's special meaning | |
617 | * each time. The "todo" path always starts with at least one slash, the "done" path always ends in no | |
618 | * slash. We always keep an O_PATH fd to the component we are currently processing, thus keeping lookup races | |
fc4b68e5 LP |
619 | * at a minimum. |
620 | * | |
621 | * Suggested usage: whenever you want to canonicalize a path, use this function. Pass the absolute path you got | |
622 | * as-is: fully qualified and relative to your host's root. Optionally, specify the root parameter to tell this | |
623 | * function what to do when encountering a symlink with an absolute path as directory: prefix it by the | |
624 | * specified path. | |
625 | * | |
626 | * Note: there's also chase_symlinks_prefix() (see below), which as first step prefixes the passed path by the | |
627 | * passed root. */ | |
d944dc95 | 628 | |
c4f4fce7 LP |
629 | if (original_root) { |
630 | r = path_make_absolute_cwd(original_root, &root); | |
d944dc95 LP |
631 | if (r < 0) |
632 | return r; | |
c4f4fce7 LP |
633 | |
634 | if (flags & CHASE_PREFIX_ROOT) | |
635 | path = prefix_roota(root, path); | |
d944dc95 LP |
636 | } |
637 | ||
c4f4fce7 LP |
638 | r = path_make_absolute_cwd(path, &buffer); |
639 | if (r < 0) | |
640 | return r; | |
641 | ||
d944dc95 LP |
642 | fd = open("/", O_CLOEXEC|O_NOFOLLOW|O_PATH); |
643 | if (fd < 0) | |
644 | return -errno; | |
645 | ||
646 | todo = buffer; | |
647 | for (;;) { | |
648 | _cleanup_free_ char *first = NULL; | |
649 | _cleanup_close_ int child = -1; | |
650 | struct stat st; | |
651 | size_t n, m; | |
652 | ||
653 | /* Determine length of first component in the path */ | |
654 | n = strspn(todo, "/"); /* The slashes */ | |
655 | m = n + strcspn(todo + n, "/"); /* The entire length of the component */ | |
656 | ||
657 | /* Extract the first component. */ | |
658 | first = strndup(todo, m); | |
659 | if (!first) | |
660 | return -ENOMEM; | |
661 | ||
662 | todo += m; | |
663 | ||
664 | /* Just a single slash? Then we reached the end. */ | |
665 | if (isempty(first) || path_equal(first, "/")) | |
666 | break; | |
667 | ||
668 | /* Just a dot? Then let's eat this up. */ | |
669 | if (path_equal(first, "/.")) | |
670 | continue; | |
671 | ||
672 | /* Two dots? Then chop off the last bit of what we already found out. */ | |
673 | if (path_equal(first, "/..")) { | |
674 | _cleanup_free_ char *parent = NULL; | |
675 | int fd_parent = -1; | |
676 | ||
a4eaf3cf LP |
677 | /* If we already are at the top, then going up will not change anything. This is in-line with |
678 | * how the kernel handles this. */ | |
d944dc95 | 679 | if (isempty(done) || path_equal(done, "/")) |
a4eaf3cf | 680 | continue; |
d944dc95 LP |
681 | |
682 | parent = dirname_malloc(done); | |
683 | if (!parent) | |
684 | return -ENOMEM; | |
685 | ||
a4eaf3cf | 686 | /* Don't allow this to leave the root dir. */ |
d944dc95 LP |
687 | if (root && |
688 | path_startswith(done, root) && | |
689 | !path_startswith(parent, root)) | |
a4eaf3cf | 690 | continue; |
d944dc95 | 691 | |
3b319885 | 692 | free_and_replace(done, parent); |
d944dc95 LP |
693 | |
694 | fd_parent = openat(fd, "..", O_CLOEXEC|O_NOFOLLOW|O_PATH); | |
695 | if (fd_parent < 0) | |
696 | return -errno; | |
697 | ||
698 | safe_close(fd); | |
699 | fd = fd_parent; | |
700 | ||
701 | continue; | |
702 | } | |
703 | ||
704 | /* Otherwise let's see what this is. */ | |
705 | child = openat(fd, first + n, O_CLOEXEC|O_NOFOLLOW|O_PATH); | |
a9fb0867 LP |
706 | if (child < 0) { |
707 | ||
708 | if (errno == ENOENT && | |
cb638b5e | 709 | (flags & CHASE_NONEXISTENT) && |
a9fb0867 LP |
710 | (isempty(todo) || path_is_safe(todo))) { |
711 | ||
cb638b5e | 712 | /* If CHASE_NONEXISTENT is set, and the path does not exist, then that's OK, return |
a9fb0867 LP |
713 | * what we got so far. But don't allow this if the remaining path contains "../ or "./" |
714 | * or something else weird. */ | |
715 | ||
716 | if (!strextend(&done, first, todo, NULL)) | |
717 | return -ENOMEM; | |
718 | ||
719 | exists = false; | |
720 | break; | |
721 | } | |
722 | ||
d944dc95 | 723 | return -errno; |
a9fb0867 | 724 | } |
d944dc95 LP |
725 | |
726 | if (fstat(child, &st) < 0) | |
727 | return -errno; | |
655f2da0 N |
728 | if ((flags & CHASE_NO_AUTOFS) && |
729 | fd_check_fstype(child, AUTOFS_SUPER_MAGIC) > 0) | |
730 | return -EREMOTE; | |
d944dc95 LP |
731 | |
732 | if (S_ISLNK(st.st_mode)) { | |
877777d7 CCW |
733 | char *joined; |
734 | ||
d944dc95 LP |
735 | _cleanup_free_ char *destination = NULL; |
736 | ||
737 | /* This is a symlink, in this case read the destination. But let's make sure we don't follow | |
738 | * symlinks without bounds. */ | |
739 | if (--max_follow <= 0) | |
740 | return -ELOOP; | |
741 | ||
742 | r = readlinkat_malloc(fd, first + n, &destination); | |
743 | if (r < 0) | |
744 | return r; | |
745 | if (isempty(destination)) | |
746 | return -EINVAL; | |
747 | ||
748 | if (path_is_absolute(destination)) { | |
749 | ||
750 | /* An absolute destination. Start the loop from the beginning, but use the root | |
751 | * directory as base. */ | |
752 | ||
753 | safe_close(fd); | |
754 | fd = open(root ?: "/", O_CLOEXEC|O_NOFOLLOW|O_PATH); | |
755 | if (fd < 0) | |
756 | return -errno; | |
757 | ||
d944dc95 LP |
758 | free(done); |
759 | ||
760 | /* Note that we do not revalidate the root, we take it as is. */ | |
761 | if (isempty(root)) | |
762 | done = NULL; | |
763 | else { | |
764 | done = strdup(root); | |
765 | if (!done) | |
766 | return -ENOMEM; | |
767 | } | |
768 | ||
877777d7 | 769 | } |
d944dc95 | 770 | |
877777d7 CCW |
771 | /* Prefix what's left to do with what we just read, and start the loop again, |
772 | * but remain in the current directory. */ | |
d944dc95 | 773 | |
877777d7 CCW |
774 | joined = strjoin("/", destination, todo); |
775 | if (!joined) | |
776 | return -ENOMEM; | |
d944dc95 | 777 | |
877777d7 CCW |
778 | free(buffer); |
779 | todo = buffer = joined; | |
d944dc95 LP |
780 | |
781 | continue; | |
782 | } | |
783 | ||
784 | /* If this is not a symlink, then let's just add the name we read to what we already verified. */ | |
785 | if (!done) { | |
786 | done = first; | |
787 | first = NULL; | |
788 | } else { | |
789 | if (!strextend(&done, first, NULL)) | |
790 | return -ENOMEM; | |
791 | } | |
792 | ||
793 | /* And iterate again, but go one directory further down. */ | |
794 | safe_close(fd); | |
795 | fd = child; | |
796 | child = -1; | |
797 | } | |
798 | ||
799 | if (!done) { | |
800 | /* Special case, turn the empty string into "/", to indicate the root directory. */ | |
801 | done = strdup("/"); | |
802 | if (!done) | |
803 | return -ENOMEM; | |
804 | } | |
805 | ||
245f1d24 LP |
806 | if (ret) { |
807 | *ret = done; | |
808 | done = NULL; | |
809 | } | |
d944dc95 | 810 | |
a9fb0867 | 811 | return exists; |
d944dc95 | 812 | } |