]>
Commit | Line | Data |
---|---|---|
53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
f4f15635 | 2 | |
11c3a366 TA |
3 | #include <errno.h> |
4 | #include <stddef.h> | |
5 | #include <stdio.h> | |
6 | #include <stdlib.h> | |
7 | #include <string.h> | |
8 | #include <sys/stat.h> | |
655f2da0 | 9 | #include <linux/magic.h> |
11c3a366 TA |
10 | #include <time.h> |
11 | #include <unistd.h> | |
12 | ||
b5efdb8a | 13 | #include "alloc-util.h" |
f4f15635 LP |
14 | #include "dirent-util.h" |
15 | #include "fd-util.h" | |
f4f15635 | 16 | #include "fs-util.h" |
fd74c6f3 | 17 | #include "locale-util.h" |
11c3a366 TA |
18 | #include "log.h" |
19 | #include "macro.h" | |
20 | #include "missing.h" | |
93cc7779 TA |
21 | #include "mkdir.h" |
22 | #include "parse-util.h" | |
23 | #include "path-util.h" | |
dccca82b | 24 | #include "process-util.h" |
34a8f081 | 25 | #include "stat-util.h" |
430fbf8e | 26 | #include "stdio-util.h" |
f4f15635 LP |
27 | #include "string-util.h" |
28 | #include "strv.h" | |
93cc7779 | 29 | #include "time-util.h" |
e4de7287 | 30 | #include "tmpfile-util.h" |
ee104e11 | 31 | #include "user-util.h" |
f4f15635 LP |
32 | #include "util.h" |
33 | ||
34 | int unlink_noerrno(const char *path) { | |
35 | PROTECT_ERRNO; | |
36 | int r; | |
37 | ||
38 | r = unlink(path); | |
39 | if (r < 0) | |
40 | return -errno; | |
41 | ||
42 | return 0; | |
43 | } | |
44 | ||
45 | int rmdir_parents(const char *path, const char *stop) { | |
46 | size_t l; | |
47 | int r = 0; | |
48 | ||
49 | assert(path); | |
50 | assert(stop); | |
51 | ||
52 | l = strlen(path); | |
53 | ||
54 | /* Skip trailing slashes */ | |
55 | while (l > 0 && path[l-1] == '/') | |
56 | l--; | |
57 | ||
58 | while (l > 0) { | |
59 | char *t; | |
60 | ||
61 | /* Skip last component */ | |
62 | while (l > 0 && path[l-1] != '/') | |
63 | l--; | |
64 | ||
65 | /* Skip trailing slashes */ | |
66 | while (l > 0 && path[l-1] == '/') | |
67 | l--; | |
68 | ||
69 | if (l <= 0) | |
70 | break; | |
71 | ||
72 | t = strndup(path, l); | |
73 | if (!t) | |
74 | return -ENOMEM; | |
75 | ||
76 | if (path_startswith(stop, t)) { | |
77 | free(t); | |
78 | return 0; | |
79 | } | |
80 | ||
81 | r = rmdir(t); | |
82 | free(t); | |
83 | ||
84 | if (r < 0) | |
85 | if (errno != ENOENT) | |
86 | return -errno; | |
87 | } | |
88 | ||
89 | return 0; | |
90 | } | |
91 | ||
f4f15635 | 92 | int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath) { |
2f15b625 | 93 | int r; |
f4f15635 | 94 | |
2f15b625 LP |
95 | /* Try the ideal approach first */ |
96 | if (renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE) >= 0) | |
f4f15635 LP |
97 | return 0; |
98 | ||
2f15b625 LP |
99 | /* renameat2() exists since Linux 3.15, btrfs and FAT added support for it later. If it is not implemented, |
100 | * fall back to a different method. */ | |
101 | if (!IN_SET(errno, EINVAL, ENOSYS, ENOTTY)) | |
f4f15635 LP |
102 | return -errno; |
103 | ||
2f15b625 LP |
104 | /* Let's try to use linkat()+unlinkat() as fallback. This doesn't work on directories and on some file systems |
105 | * that do not support hard links (such as FAT, most prominently), but for files it's pretty close to what we | |
106 | * want — though not atomic (i.e. for a short period both the new and the old filename will exist). */ | |
107 | if (linkat(olddirfd, oldpath, newdirfd, newpath, 0) >= 0) { | |
108 | ||
109 | if (unlinkat(olddirfd, oldpath, 0) < 0) { | |
110 | r = -errno; /* Backup errno before the following unlinkat() alters it */ | |
111 | (void) unlinkat(newdirfd, newpath, 0); | |
112 | return r; | |
113 | } | |
114 | ||
115 | return 0; | |
f4f15635 LP |
116 | } |
117 | ||
2f15b625 | 118 | if (!IN_SET(errno, EINVAL, ENOSYS, ENOTTY, EPERM)) /* FAT returns EPERM on link()… */ |
f4f15635 LP |
119 | return -errno; |
120 | ||
2f15b625 LP |
121 | /* OK, neither RENAME_NOREPLACE nor linkat()+unlinkat() worked. Let's then fallback to the racy TOCTOU |
122 | * vulnerable accessat(F_OK) check followed by classic, replacing renameat(), we have nothing better. */ | |
123 | ||
124 | if (faccessat(newdirfd, newpath, F_OK, AT_SYMLINK_NOFOLLOW) >= 0) | |
125 | return -EEXIST; | |
126 | if (errno != ENOENT) | |
127 | return -errno; | |
128 | ||
129 | if (renameat(olddirfd, oldpath, newdirfd, newpath) < 0) | |
f4f15635 | 130 | return -errno; |
f4f15635 LP |
131 | |
132 | return 0; | |
133 | } | |
134 | ||
135 | int readlinkat_malloc(int fd, const char *p, char **ret) { | |
8e060ec2 | 136 | size_t l = FILENAME_MAX+1; |
f4f15635 LP |
137 | int r; |
138 | ||
139 | assert(p); | |
140 | assert(ret); | |
141 | ||
142 | for (;;) { | |
143 | char *c; | |
144 | ssize_t n; | |
145 | ||
146 | c = new(char, l); | |
147 | if (!c) | |
148 | return -ENOMEM; | |
149 | ||
150 | n = readlinkat(fd, p, c, l-1); | |
151 | if (n < 0) { | |
152 | r = -errno; | |
153 | free(c); | |
154 | return r; | |
155 | } | |
156 | ||
157 | if ((size_t) n < l-1) { | |
158 | c[n] = 0; | |
159 | *ret = c; | |
160 | return 0; | |
161 | } | |
162 | ||
163 | free(c); | |
164 | l *= 2; | |
165 | } | |
166 | } | |
167 | ||
168 | int readlink_malloc(const char *p, char **ret) { | |
169 | return readlinkat_malloc(AT_FDCWD, p, ret); | |
170 | } | |
171 | ||
172 | int readlink_value(const char *p, char **ret) { | |
173 | _cleanup_free_ char *link = NULL; | |
174 | char *value; | |
175 | int r; | |
176 | ||
177 | r = readlink_malloc(p, &link); | |
178 | if (r < 0) | |
179 | return r; | |
180 | ||
181 | value = basename(link); | |
182 | if (!value) | |
183 | return -ENOENT; | |
184 | ||
185 | value = strdup(value); | |
186 | if (!value) | |
187 | return -ENOMEM; | |
188 | ||
189 | *ret = value; | |
190 | ||
191 | return 0; | |
192 | } | |
193 | ||
194 | int readlink_and_make_absolute(const char *p, char **r) { | |
195 | _cleanup_free_ char *target = NULL; | |
196 | char *k; | |
197 | int j; | |
198 | ||
199 | assert(p); | |
200 | assert(r); | |
201 | ||
202 | j = readlink_malloc(p, &target); | |
203 | if (j < 0) | |
204 | return j; | |
205 | ||
206 | k = file_in_same_dir(p, target); | |
207 | if (!k) | |
208 | return -ENOMEM; | |
209 | ||
210 | *r = k; | |
211 | return 0; | |
212 | } | |
213 | ||
f4f15635 | 214 | int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid) { |
de321f52 LP |
215 | char fd_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1]; |
216 | _cleanup_close_ int fd = -1; | |
f4f15635 LP |
217 | assert(path); |
218 | ||
de321f52 | 219 | /* Under the assumption that we are running privileged we first change the access mode and only then hand out |
f4f15635 LP |
220 | * ownership to avoid a window where access is too open. */ |
221 | ||
de321f52 LP |
222 | fd = open(path, O_PATH|O_CLOEXEC|O_NOFOLLOW); /* Let's acquire an O_PATH fd, as precaution to change mode/owner |
223 | * on the same file */ | |
224 | if (fd < 0) | |
225 | return -errno; | |
226 | ||
227 | xsprintf(fd_path, "/proc/self/fd/%i", fd); | |
228 | ||
229 | if (mode != MODE_INVALID) { | |
230 | ||
231 | if ((mode & S_IFMT) != 0) { | |
232 | struct stat st; | |
233 | ||
234 | if (stat(fd_path, &st) < 0) | |
235 | return -errno; | |
236 | ||
237 | if ((mode & S_IFMT) != (st.st_mode & S_IFMT)) | |
238 | return -EINVAL; | |
239 | } | |
240 | ||
241 | if (chmod(fd_path, mode & 07777) < 0) | |
f4f15635 | 242 | return -errno; |
de321f52 | 243 | } |
f4f15635 LP |
244 | |
245 | if (uid != UID_INVALID || gid != GID_INVALID) | |
de321f52 | 246 | if (chown(fd_path, uid, gid) < 0) |
f4f15635 | 247 | return -errno; |
b8da477e YW |
248 | |
249 | return 0; | |
250 | } | |
251 | ||
252 | int fchmod_and_chown(int fd, mode_t mode, uid_t uid, gid_t gid) { | |
de321f52 | 253 | /* Under the assumption that we are running privileged we first change the access mode and only then hand out |
b8da477e YW |
254 | * ownership to avoid a window where access is too open. */ |
255 | ||
de321f52 LP |
256 | if (mode != MODE_INVALID) { |
257 | ||
258 | if ((mode & S_IFMT) != 0) { | |
259 | struct stat st; | |
260 | ||
261 | if (fstat(fd, &st) < 0) | |
262 | return -errno; | |
263 | ||
264 | if ((mode & S_IFMT) != (st.st_mode & S_IFMT)) | |
265 | return -EINVAL; | |
266 | } | |
267 | ||
268 | if (fchmod(fd, mode & 0777) < 0) | |
b8da477e | 269 | return -errno; |
de321f52 | 270 | } |
b8da477e YW |
271 | |
272 | if (uid != UID_INVALID || gid != GID_INVALID) | |
273 | if (fchown(fd, uid, gid) < 0) | |
274 | return -errno; | |
f4f15635 LP |
275 | |
276 | return 0; | |
277 | } | |
278 | ||
f4f15635 LP |
279 | int fchmod_umask(int fd, mode_t m) { |
280 | mode_t u; | |
281 | int r; | |
282 | ||
283 | u = umask(0777); | |
284 | r = fchmod(fd, m & (~u)) < 0 ? -errno : 0; | |
285 | umask(u); | |
286 | ||
287 | return r; | |
288 | } | |
289 | ||
4dfaa528 | 290 | int fchmod_opath(int fd, mode_t m) { |
22dd8d35 | 291 | char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; |
4dfaa528 FB |
292 | |
293 | /* This function operates also on fd that might have been opened with | |
294 | * O_PATH. Indeed fchmodat() doesn't have the AT_EMPTY_PATH flag like | |
295 | * fchownat() does. */ | |
296 | ||
297 | xsprintf(procfs_path, "/proc/self/fd/%i", fd); | |
4dfaa528 FB |
298 | if (chmod(procfs_path, m) < 0) |
299 | return -errno; | |
300 | ||
301 | return 0; | |
302 | } | |
303 | ||
f4f15635 LP |
304 | int fd_warn_permissions(const char *path, int fd) { |
305 | struct stat st; | |
306 | ||
307 | if (fstat(fd, &st) < 0) | |
308 | return -errno; | |
309 | ||
310 | if (st.st_mode & 0111) | |
311 | log_warning("Configuration file %s is marked executable. Please remove executable permission bits. Proceeding anyway.", path); | |
312 | ||
313 | if (st.st_mode & 0002) | |
314 | log_warning("Configuration file %s is marked world-writable. Please remove world writability permission bits. Proceeding anyway.", path); | |
315 | ||
df0ff127 | 316 | if (getpid_cached() == 1 && (st.st_mode & 0044) != 0044) |
f4f15635 LP |
317 | 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); |
318 | ||
319 | return 0; | |
320 | } | |
321 | ||
322 | int touch_file(const char *path, bool parents, usec_t stamp, uid_t uid, gid_t gid, mode_t mode) { | |
9e3fa6e8 LP |
323 | char fdpath[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; |
324 | _cleanup_close_ int fd = -1; | |
325 | int r, ret = 0; | |
f4f15635 LP |
326 | |
327 | assert(path); | |
328 | ||
9e3fa6e8 LP |
329 | /* Note that touch_file() does not follow symlinks: if invoked on an existing symlink, then it is the symlink |
330 | * itself which is updated, not its target | |
331 | * | |
332 | * Returns the first error we encounter, but tries to apply as much as possible. */ | |
f4f15635 | 333 | |
9e3fa6e8 LP |
334 | if (parents) |
335 | (void) mkdir_parents(path, 0755); | |
336 | ||
337 | /* Initially, we try to open the node with O_PATH, so that we get a reference to the node. This is useful in | |
338 | * case the path refers to an existing device or socket node, as we can open it successfully in all cases, and | |
339 | * won't trigger any driver magic or so. */ | |
340 | fd = open(path, O_PATH|O_CLOEXEC|O_NOFOLLOW); | |
341 | if (fd < 0) { | |
342 | if (errno != ENOENT) | |
f4f15635 | 343 | return -errno; |
f4f15635 | 344 | |
9e3fa6e8 LP |
345 | /* if the node doesn't exist yet, we create it, but with O_EXCL, so that we only create a regular file |
346 | * here, and nothing else */ | |
347 | fd = open(path, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, IN_SET(mode, 0, MODE_INVALID) ? 0644 : mode); | |
348 | if (fd < 0) | |
f4f15635 LP |
349 | return -errno; |
350 | } | |
351 | ||
9e3fa6e8 LP |
352 | /* Let's make a path from the fd, and operate on that. With this logic, we can adjust the access mode, |
353 | * ownership and time of the file node in all cases, even if the fd refers to an O_PATH object — which is | |
354 | * something fchown(), fchmod(), futimensat() don't allow. */ | |
355 | xsprintf(fdpath, "/proc/self/fd/%i", fd); | |
356 | ||
357 | if (mode != MODE_INVALID) | |
358 | if (chmod(fdpath, mode) < 0) | |
359 | ret = -errno; | |
360 | ||
361 | if (uid_is_valid(uid) || gid_is_valid(gid)) | |
362 | if (chown(fdpath, uid, gid) < 0 && ret >= 0) | |
363 | ret = -errno; | |
364 | ||
f4f15635 LP |
365 | if (stamp != USEC_INFINITY) { |
366 | struct timespec ts[2]; | |
367 | ||
368 | timespec_store(&ts[0], stamp); | |
369 | ts[1] = ts[0]; | |
9e3fa6e8 | 370 | r = utimensat(AT_FDCWD, fdpath, ts, 0); |
f4f15635 | 371 | } else |
9e3fa6e8 LP |
372 | r = utimensat(AT_FDCWD, fdpath, NULL, 0); |
373 | if (r < 0 && ret >= 0) | |
f4f15635 LP |
374 | return -errno; |
375 | ||
9e3fa6e8 | 376 | return ret; |
f4f15635 LP |
377 | } |
378 | ||
379 | int touch(const char *path) { | |
ee735086 | 380 | return touch_file(path, false, USEC_INFINITY, UID_INVALID, GID_INVALID, MODE_INVALID); |
f4f15635 LP |
381 | } |
382 | ||
6c9c51e5 YW |
383 | int symlink_idempotent(const char *from, const char *to, bool make_relative) { |
384 | _cleanup_free_ char *relpath = NULL; | |
f4f15635 LP |
385 | int r; |
386 | ||
387 | assert(from); | |
388 | assert(to); | |
389 | ||
6c9c51e5 YW |
390 | if (make_relative) { |
391 | _cleanup_free_ char *parent = NULL; | |
392 | ||
393 | parent = dirname_malloc(to); | |
394 | if (!parent) | |
395 | return -ENOMEM; | |
396 | ||
397 | r = path_make_relative(parent, from, &relpath); | |
398 | if (r < 0) | |
399 | return r; | |
400 | ||
401 | from = relpath; | |
402 | } | |
403 | ||
f4f15635 | 404 | if (symlink(from, to) < 0) { |
77b79723 LP |
405 | _cleanup_free_ char *p = NULL; |
406 | ||
f4f15635 LP |
407 | if (errno != EEXIST) |
408 | return -errno; | |
409 | ||
410 | r = readlink_malloc(to, &p); | |
77b79723 LP |
411 | if (r == -EINVAL) /* Not a symlink? In that case return the original error we encountered: -EEXIST */ |
412 | return -EEXIST; | |
413 | if (r < 0) /* Any other error? In that case propagate it as is */ | |
f4f15635 LP |
414 | return r; |
415 | ||
77b79723 LP |
416 | if (!streq(p, from)) /* Not the symlink we want it to be? In that case, propagate the original -EEXIST */ |
417 | return -EEXIST; | |
f4f15635 LP |
418 | } |
419 | ||
420 | return 0; | |
421 | } | |
422 | ||
423 | int symlink_atomic(const char *from, const char *to) { | |
424 | _cleanup_free_ char *t = NULL; | |
425 | int r; | |
426 | ||
427 | assert(from); | |
428 | assert(to); | |
429 | ||
430 | r = tempfn_random(to, NULL, &t); | |
431 | if (r < 0) | |
432 | return r; | |
433 | ||
434 | if (symlink(from, t) < 0) | |
435 | return -errno; | |
436 | ||
437 | if (rename(t, to) < 0) { | |
438 | unlink_noerrno(t); | |
439 | return -errno; | |
440 | } | |
441 | ||
442 | return 0; | |
443 | } | |
444 | ||
445 | int mknod_atomic(const char *path, mode_t mode, dev_t dev) { | |
446 | _cleanup_free_ char *t = NULL; | |
447 | int r; | |
448 | ||
449 | assert(path); | |
450 | ||
451 | r = tempfn_random(path, NULL, &t); | |
452 | if (r < 0) | |
453 | return r; | |
454 | ||
455 | if (mknod(t, mode, dev) < 0) | |
456 | return -errno; | |
457 | ||
458 | if (rename(t, path) < 0) { | |
459 | unlink_noerrno(t); | |
460 | return -errno; | |
461 | } | |
462 | ||
463 | return 0; | |
464 | } | |
465 | ||
466 | int mkfifo_atomic(const char *path, mode_t mode) { | |
467 | _cleanup_free_ char *t = NULL; | |
468 | int r; | |
469 | ||
470 | assert(path); | |
471 | ||
472 | r = tempfn_random(path, NULL, &t); | |
473 | if (r < 0) | |
474 | return r; | |
475 | ||
476 | if (mkfifo(t, mode) < 0) | |
477 | return -errno; | |
478 | ||
479 | if (rename(t, path) < 0) { | |
4fe3828c FB |
480 | unlink_noerrno(t); |
481 | return -errno; | |
482 | } | |
483 | ||
484 | return 0; | |
485 | } | |
486 | ||
487 | int mkfifoat_atomic(int dirfd, const char *path, mode_t mode) { | |
488 | _cleanup_free_ char *t = NULL; | |
489 | int r; | |
490 | ||
491 | assert(path); | |
492 | ||
493 | if (path_is_absolute(path)) | |
494 | return mkfifo_atomic(path, mode); | |
495 | ||
496 | /* We're only interested in the (random) filename. */ | |
497 | r = tempfn_random_child("", NULL, &t); | |
498 | if (r < 0) | |
499 | return r; | |
500 | ||
501 | if (mkfifoat(dirfd, t, mode) < 0) | |
502 | return -errno; | |
503 | ||
504 | if (renameat(dirfd, t, dirfd, path) < 0) { | |
f4f15635 LP |
505 | unlink_noerrno(t); |
506 | return -errno; | |
507 | } | |
508 | ||
509 | return 0; | |
510 | } | |
511 | ||
512 | int get_files_in_directory(const char *path, char ***list) { | |
513 | _cleanup_closedir_ DIR *d = NULL; | |
8fb3f009 | 514 | struct dirent *de; |
f4f15635 LP |
515 | size_t bufsize = 0, n = 0; |
516 | _cleanup_strv_free_ char **l = NULL; | |
517 | ||
518 | assert(path); | |
519 | ||
520 | /* Returns all files in a directory in *list, and the number | |
521 | * of files as return value. If list is NULL returns only the | |
522 | * number. */ | |
523 | ||
524 | d = opendir(path); | |
525 | if (!d) | |
526 | return -errno; | |
527 | ||
8fb3f009 | 528 | FOREACH_DIRENT_ALL(de, d, return -errno) { |
f4f15635 LP |
529 | dirent_ensure_type(d, de); |
530 | ||
531 | if (!dirent_is_file(de)) | |
532 | continue; | |
533 | ||
534 | if (list) { | |
535 | /* one extra slot is needed for the terminating NULL */ | |
536 | if (!GREEDY_REALLOC(l, bufsize, n + 2)) | |
537 | return -ENOMEM; | |
538 | ||
539 | l[n] = strdup(de->d_name); | |
540 | if (!l[n]) | |
541 | return -ENOMEM; | |
542 | ||
543 | l[++n] = NULL; | |
544 | } else | |
545 | n++; | |
546 | } | |
547 | ||
ae2a15bc LP |
548 | if (list) |
549 | *list = TAKE_PTR(l); | |
f4f15635 LP |
550 | |
551 | return n; | |
552 | } | |
430fbf8e | 553 | |
992e8f22 LP |
554 | static int getenv_tmp_dir(const char **ret_path) { |
555 | const char *n; | |
556 | int r, ret = 0; | |
34a8f081 | 557 | |
992e8f22 | 558 | assert(ret_path); |
34a8f081 | 559 | |
992e8f22 LP |
560 | /* We use the same order of environment variables python uses in tempfile.gettempdir(): |
561 | * https://docs.python.org/3/library/tempfile.html#tempfile.gettempdir */ | |
562 | FOREACH_STRING(n, "TMPDIR", "TEMP", "TMP") { | |
563 | const char *e; | |
564 | ||
565 | e = secure_getenv(n); | |
566 | if (!e) | |
567 | continue; | |
568 | if (!path_is_absolute(e)) { | |
569 | r = -ENOTDIR; | |
570 | goto next; | |
571 | } | |
99be45a4 | 572 | if (!path_is_normalized(e)) { |
992e8f22 LP |
573 | r = -EPERM; |
574 | goto next; | |
575 | } | |
576 | ||
577 | r = is_dir(e, true); | |
578 | if (r < 0) | |
579 | goto next; | |
580 | if (r == 0) { | |
581 | r = -ENOTDIR; | |
582 | goto next; | |
583 | } | |
584 | ||
585 | *ret_path = e; | |
586 | return 1; | |
587 | ||
588 | next: | |
589 | /* Remember first error, to make this more debuggable */ | |
590 | if (ret >= 0) | |
591 | ret = r; | |
34a8f081 OW |
592 | } |
593 | ||
992e8f22 LP |
594 | if (ret < 0) |
595 | return ret; | |
34a8f081 | 596 | |
992e8f22 LP |
597 | *ret_path = NULL; |
598 | return ret; | |
599 | } | |
34a8f081 | 600 | |
992e8f22 LP |
601 | static int tmp_dir_internal(const char *def, const char **ret) { |
602 | const char *e; | |
603 | int r, k; | |
604 | ||
605 | assert(def); | |
606 | assert(ret); | |
607 | ||
608 | r = getenv_tmp_dir(&e); | |
609 | if (r > 0) { | |
610 | *ret = e; | |
611 | return 0; | |
612 | } | |
613 | ||
614 | k = is_dir(def, true); | |
615 | if (k == 0) | |
616 | k = -ENOTDIR; | |
617 | if (k < 0) | |
618 | return r < 0 ? r : k; | |
619 | ||
620 | *ret = def; | |
34a8f081 OW |
621 | return 0; |
622 | } | |
623 | ||
992e8f22 LP |
624 | int var_tmp_dir(const char **ret) { |
625 | ||
626 | /* Returns the location for "larger" temporary files, that is backed by physical storage if available, and thus | |
627 | * even might survive a boot: /var/tmp. If $TMPDIR (or related environment variables) are set, its value is | |
628 | * returned preferably however. Note that both this function and tmp_dir() below are affected by $TMPDIR, | |
629 | * making it a variable that overrides all temporary file storage locations. */ | |
630 | ||
631 | return tmp_dir_internal("/var/tmp", ret); | |
632 | } | |
633 | ||
634 | int tmp_dir(const char **ret) { | |
635 | ||
636 | /* Similar to var_tmp_dir() above, but returns the location for "smaller" temporary files, which is usually | |
637 | * backed by an in-memory file system: /tmp. */ | |
638 | ||
639 | return tmp_dir_internal("/tmp", ret); | |
640 | } | |
641 | ||
af229d7a ZJS |
642 | int unlink_or_warn(const char *filename) { |
643 | if (unlink(filename) < 0 && errno != ENOENT) | |
644 | /* If the file doesn't exist and the fs simply was read-only (in which | |
645 | * case unlink() returns EROFS even if the file doesn't exist), don't | |
646 | * complain */ | |
647 | if (errno != EROFS || access(filename, F_OK) >= 0) | |
648 | return log_error_errno(errno, "Failed to remove \"%s\": %m", filename); | |
649 | ||
650 | return 0; | |
651 | } | |
652 | ||
430fbf8e | 653 | int inotify_add_watch_fd(int fd, int what, uint32_t mask) { |
fbd0b64f | 654 | char path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1]; |
430fbf8e LP |
655 | int r; |
656 | ||
657 | /* This is like inotify_add_watch(), except that the file to watch is not referenced by a path, but by an fd */ | |
658 | xsprintf(path, "/proc/self/fd/%i", what); | |
659 | ||
660 | r = inotify_add_watch(fd, path, mask); | |
661 | if (r < 0) | |
662 | return -errno; | |
663 | ||
664 | return r; | |
665 | } | |
d944dc95 | 666 | |
b85ee2ec | 667 | static bool unsafe_transition(const struct stat *a, const struct stat *b) { |
f14f1806 LP |
668 | /* Returns true if the transition from a to b is safe, i.e. that we never transition from unprivileged to |
669 | * privileged files or directories. Why bother? So that unprivileged code can't symlink to privileged files | |
670 | * making us believe we read something safe even though it isn't safe in the specific context we open it in. */ | |
671 | ||
672 | if (a->st_uid == 0) /* Transitioning from privileged to unprivileged is always fine */ | |
b85ee2ec | 673 | return false; |
f14f1806 | 674 | |
b85ee2ec | 675 | return a->st_uid != b->st_uid; /* Otherwise we need to stay within the same UID */ |
f14f1806 LP |
676 | } |
677 | ||
fd74c6f3 FB |
678 | static int log_unsafe_transition(int a, int b, const char *path, unsigned flags) { |
679 | _cleanup_free_ char *n1 = NULL, *n2 = NULL; | |
680 | ||
681 | if (!FLAGS_SET(flags, CHASE_WARN)) | |
36c97dec | 682 | return -ENOLINK; |
fd74c6f3 FB |
683 | |
684 | (void) fd_get_path(a, &n1); | |
685 | (void) fd_get_path(b, &n2); | |
686 | ||
36c97dec | 687 | return log_warning_errno(SYNTHETIC_ERRNO(ENOLINK), |
fd74c6f3 | 688 | "Detected unsafe path transition %s %s %s during canonicalization of %s.", |
9a6f746f | 689 | n1, special_glyph(SPECIAL_GLYPH_ARROW), n2, path); |
fd74c6f3 FB |
690 | } |
691 | ||
145b8d0f FB |
692 | static int log_autofs_mount_point(int fd, const char *path, unsigned flags) { |
693 | _cleanup_free_ char *n1 = NULL; | |
694 | ||
695 | if (!FLAGS_SET(flags, CHASE_WARN)) | |
696 | return -EREMOTE; | |
697 | ||
698 | (void) fd_get_path(fd, &n1); | |
699 | ||
700 | return log_warning_errno(SYNTHETIC_ERRNO(EREMOTE), | |
701 | "Detected autofs mount point %s during canonicalization of %s.", | |
702 | n1, path); | |
f14f1806 LP |
703 | } |
704 | ||
c4f4fce7 | 705 | int chase_symlinks(const char *path, const char *original_root, unsigned flags, char **ret) { |
d944dc95 LP |
706 | _cleanup_free_ char *buffer = NULL, *done = NULL, *root = NULL; |
707 | _cleanup_close_ int fd = -1; | |
f10f4215 | 708 | unsigned max_follow = CHASE_SYMLINKS_MAX; /* how many symlinks to follow before giving up and returning ELOOP */ |
f14f1806 | 709 | struct stat previous_stat; |
a9fb0867 | 710 | bool exists = true; |
d944dc95 LP |
711 | char *todo; |
712 | int r; | |
713 | ||
714 | assert(path); | |
715 | ||
1ed34d75 | 716 | /* Either the file may be missing, or we return an fd to the final object, but both make no sense */ |
d94a24ca | 717 | if (FLAGS_SET(flags, CHASE_NONEXISTENT | CHASE_OPEN)) |
1ed34d75 LP |
718 | return -EINVAL; |
719 | ||
d94a24ca | 720 | if (FLAGS_SET(flags, CHASE_STEP | CHASE_OPEN)) |
49eb3659 LP |
721 | return -EINVAL; |
722 | ||
a49424af LP |
723 | if (isempty(path)) |
724 | return -EINVAL; | |
725 | ||
d944dc95 LP |
726 | /* This is a lot like canonicalize_file_name(), but takes an additional "root" parameter, that allows following |
727 | * symlinks relative to a root directory, instead of the root of the host. | |
728 | * | |
fc4b68e5 | 729 | * Note that "root" primarily matters if we encounter an absolute symlink. It is also used when following |
c4f4fce7 LP |
730 | * relative symlinks to ensure they cannot be used to "escape" the root directory. The path parameter passed is |
731 | * assumed to be already prefixed by it, except if the CHASE_PREFIX_ROOT flag is set, in which case it is first | |
732 | * prefixed accordingly. | |
d944dc95 LP |
733 | * |
734 | * Algorithmically this operates on two path buffers: "done" are the components of the path we already | |
735 | * processed and resolved symlinks, "." and ".." of. "todo" are the components of the path we still need to | |
736 | * process. On each iteration, we move one component from "todo" to "done", processing it's special meaning | |
737 | * each time. The "todo" path always starts with at least one slash, the "done" path always ends in no | |
738 | * slash. We always keep an O_PATH fd to the component we are currently processing, thus keeping lookup races | |
fc4b68e5 LP |
739 | * at a minimum. |
740 | * | |
741 | * Suggested usage: whenever you want to canonicalize a path, use this function. Pass the absolute path you got | |
742 | * as-is: fully qualified and relative to your host's root. Optionally, specify the root parameter to tell this | |
743 | * function what to do when encountering a symlink with an absolute path as directory: prefix it by the | |
49eb3659 LP |
744 | * specified path. |
745 | * | |
746 | * There are three ways to invoke this function: | |
747 | * | |
748 | * 1. Without CHASE_STEP or CHASE_OPEN: in this case the path is resolved and the normalized path is returned | |
749 | * in `ret`. The return value is < 0 on error. If CHASE_NONEXISTENT is also set 0 is returned if the file | |
750 | * doesn't exist, > 0 otherwise. If CHASE_NONEXISTENT is not set >= 0 is returned if the destination was | |
751 | * found, -ENOENT if it doesn't. | |
752 | * | |
753 | * 2. With CHASE_OPEN: in this case the destination is opened after chasing it as O_PATH and this file | |
754 | * descriptor is returned as return value. This is useful to open files relative to some root | |
755 | * directory. Note that the returned O_PATH file descriptors must be converted into a regular one (using | |
756 | * fd_reopen() or such) before it can be used for reading/writing. CHASE_OPEN may not be combined with | |
757 | * CHASE_NONEXISTENT. | |
758 | * | |
759 | * 3. With CHASE_STEP: in this case only a single step of the normalization is executed, i.e. only the first | |
760 | * symlink or ".." component of the path is resolved, and the resulting path is returned. This is useful if | |
761 | * a caller wants to trace the a path through the file system verbosely. Returns < 0 on error, > 0 if the | |
762 | * path is fully normalized, and == 0 for each normalization step. This may be combined with | |
763 | * CHASE_NONEXISTENT, in which case 1 is returned when a component is not found. | |
764 | * | |
36c97dec FB |
765 | * 4. With CHASE_SAFE: in this case the path must not contain unsafe transitions, i.e. transitions from |
766 | * unprivileged to privileged files or directories. In such cases the return value is -ENOLINK. If | |
767 | * CHASE_WARN is also set a warning describing the unsafe transition is emitted. | |
768 | * | |
145b8d0f FB |
769 | * 5. With CHASE_NO_AUTOFS: in this case if an autofs mount point is encountered, the path normalization is |
770 | * aborted and -EREMOTE is returned. If CHASE_WARN is also set a warning showing the path of the mount point | |
771 | * is emitted. | |
772 | * | |
49eb3659 | 773 | * */ |
d944dc95 | 774 | |
22bc57c5 | 775 | /* A root directory of "/" or "" is identical to none */ |
57ea45e1 | 776 | if (empty_or_root(original_root)) |
22bc57c5 | 777 | original_root = NULL; |
b1bfb848 | 778 | |
49eb3659 | 779 | if (!original_root && !ret && (flags & (CHASE_NONEXISTENT|CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_OPEN|CHASE_STEP)) == CHASE_OPEN) { |
244d2f07 LP |
780 | /* Shortcut the CHASE_OPEN case if the caller isn't interested in the actual path and has no root set |
781 | * and doesn't care about any of the other special features we provide either. */ | |
1f56e4ce | 782 | r = open(path, O_PATH|O_CLOEXEC|((flags & CHASE_NOFOLLOW) ? O_NOFOLLOW : 0)); |
244d2f07 LP |
783 | if (r < 0) |
784 | return -errno; | |
785 | ||
786 | return r; | |
787 | } | |
788 | ||
c4f4fce7 LP |
789 | if (original_root) { |
790 | r = path_make_absolute_cwd(original_root, &root); | |
d944dc95 LP |
791 | if (r < 0) |
792 | return r; | |
c4f4fce7 | 793 | |
382a5078 LP |
794 | if (flags & CHASE_PREFIX_ROOT) { |
795 | ||
796 | /* We don't support relative paths in combination with a root directory */ | |
797 | if (!path_is_absolute(path)) | |
798 | return -EINVAL; | |
799 | ||
c4f4fce7 | 800 | path = prefix_roota(root, path); |
382a5078 | 801 | } |
d944dc95 LP |
802 | } |
803 | ||
c4f4fce7 LP |
804 | r = path_make_absolute_cwd(path, &buffer); |
805 | if (r < 0) | |
806 | return r; | |
807 | ||
d944dc95 LP |
808 | fd = open("/", O_CLOEXEC|O_NOFOLLOW|O_PATH); |
809 | if (fd < 0) | |
810 | return -errno; | |
811 | ||
f14f1806 LP |
812 | if (flags & CHASE_SAFE) { |
813 | if (fstat(fd, &previous_stat) < 0) | |
814 | return -errno; | |
815 | } | |
816 | ||
d944dc95 LP |
817 | todo = buffer; |
818 | for (;;) { | |
819 | _cleanup_free_ char *first = NULL; | |
820 | _cleanup_close_ int child = -1; | |
821 | struct stat st; | |
822 | size_t n, m; | |
823 | ||
824 | /* Determine length of first component in the path */ | |
825 | n = strspn(todo, "/"); /* The slashes */ | |
826 | m = n + strcspn(todo + n, "/"); /* The entire length of the component */ | |
827 | ||
828 | /* Extract the first component. */ | |
829 | first = strndup(todo, m); | |
830 | if (!first) | |
831 | return -ENOMEM; | |
832 | ||
833 | todo += m; | |
834 | ||
b12d25a8 ZJS |
835 | /* Empty? Then we reached the end. */ |
836 | if (isempty(first)) | |
837 | break; | |
838 | ||
d944dc95 | 839 | /* Just a single slash? Then we reached the end. */ |
b12d25a8 ZJS |
840 | if (path_equal(first, "/")) { |
841 | /* Preserve the trailing slash */ | |
62570f6f LP |
842 | |
843 | if (flags & CHASE_TRAIL_SLASH) | |
844 | if (!strextend(&done, "/", NULL)) | |
845 | return -ENOMEM; | |
b12d25a8 | 846 | |
d944dc95 | 847 | break; |
b12d25a8 | 848 | } |
d944dc95 LP |
849 | |
850 | /* Just a dot? Then let's eat this up. */ | |
851 | if (path_equal(first, "/.")) | |
852 | continue; | |
853 | ||
854 | /* Two dots? Then chop off the last bit of what we already found out. */ | |
855 | if (path_equal(first, "/..")) { | |
856 | _cleanup_free_ char *parent = NULL; | |
2b6d2dda | 857 | _cleanup_close_ int fd_parent = -1; |
d944dc95 | 858 | |
a4eaf3cf LP |
859 | /* If we already are at the top, then going up will not change anything. This is in-line with |
860 | * how the kernel handles this. */ | |
57ea45e1 | 861 | if (empty_or_root(done)) |
a4eaf3cf | 862 | continue; |
d944dc95 LP |
863 | |
864 | parent = dirname_malloc(done); | |
865 | if (!parent) | |
866 | return -ENOMEM; | |
867 | ||
a4eaf3cf | 868 | /* Don't allow this to leave the root dir. */ |
d944dc95 LP |
869 | if (root && |
870 | path_startswith(done, root) && | |
871 | !path_startswith(parent, root)) | |
a4eaf3cf | 872 | continue; |
d944dc95 | 873 | |
3b319885 | 874 | free_and_replace(done, parent); |
d944dc95 | 875 | |
49eb3659 LP |
876 | if (flags & CHASE_STEP) |
877 | goto chased_one; | |
878 | ||
d944dc95 LP |
879 | fd_parent = openat(fd, "..", O_CLOEXEC|O_NOFOLLOW|O_PATH); |
880 | if (fd_parent < 0) | |
881 | return -errno; | |
882 | ||
f14f1806 LP |
883 | if (flags & CHASE_SAFE) { |
884 | if (fstat(fd_parent, &st) < 0) | |
885 | return -errno; | |
886 | ||
b85ee2ec | 887 | if (unsafe_transition(&previous_stat, &st)) |
fd74c6f3 | 888 | return log_unsafe_transition(fd, fd_parent, path, flags); |
f14f1806 LP |
889 | |
890 | previous_stat = st; | |
891 | } | |
892 | ||
d944dc95 | 893 | safe_close(fd); |
c10d6bdb | 894 | fd = TAKE_FD(fd_parent); |
d944dc95 LP |
895 | |
896 | continue; | |
897 | } | |
898 | ||
899 | /* Otherwise let's see what this is. */ | |
900 | child = openat(fd, first + n, O_CLOEXEC|O_NOFOLLOW|O_PATH); | |
a9fb0867 LP |
901 | if (child < 0) { |
902 | ||
903 | if (errno == ENOENT && | |
cb638b5e | 904 | (flags & CHASE_NONEXISTENT) && |
99be45a4 | 905 | (isempty(todo) || path_is_normalized(todo))) { |
a9fb0867 | 906 | |
cb638b5e | 907 | /* If CHASE_NONEXISTENT is set, and the path does not exist, then that's OK, return |
a9fb0867 LP |
908 | * what we got so far. But don't allow this if the remaining path contains "../ or "./" |
909 | * or something else weird. */ | |
910 | ||
a1904a46 YW |
911 | /* If done is "/", as first also contains slash at the head, then remove this redundant slash. */ |
912 | if (streq_ptr(done, "/")) | |
913 | *done = '\0'; | |
914 | ||
a9fb0867 LP |
915 | if (!strextend(&done, first, todo, NULL)) |
916 | return -ENOMEM; | |
917 | ||
918 | exists = false; | |
919 | break; | |
920 | } | |
921 | ||
d944dc95 | 922 | return -errno; |
a9fb0867 | 923 | } |
d944dc95 LP |
924 | |
925 | if (fstat(child, &st) < 0) | |
926 | return -errno; | |
f14f1806 | 927 | if ((flags & CHASE_SAFE) && |
b85ee2ec | 928 | unsafe_transition(&previous_stat, &st)) |
fd74c6f3 | 929 | return log_unsafe_transition(fd, child, path, flags); |
f14f1806 LP |
930 | |
931 | previous_stat = st; | |
932 | ||
655f2da0 | 933 | if ((flags & CHASE_NO_AUTOFS) && |
a66fee2e | 934 | fd_is_fs_type(child, AUTOFS_SUPER_MAGIC) > 0) |
145b8d0f | 935 | return log_autofs_mount_point(child, path, flags); |
d944dc95 | 936 | |
1f56e4ce | 937 | if (S_ISLNK(st.st_mode) && !((flags & CHASE_NOFOLLOW) && isempty(todo))) { |
877777d7 CCW |
938 | char *joined; |
939 | ||
d944dc95 LP |
940 | _cleanup_free_ char *destination = NULL; |
941 | ||
942 | /* This is a symlink, in this case read the destination. But let's make sure we don't follow | |
943 | * symlinks without bounds. */ | |
944 | if (--max_follow <= 0) | |
945 | return -ELOOP; | |
946 | ||
947 | r = readlinkat_malloc(fd, first + n, &destination); | |
948 | if (r < 0) | |
949 | return r; | |
950 | if (isempty(destination)) | |
951 | return -EINVAL; | |
952 | ||
953 | if (path_is_absolute(destination)) { | |
954 | ||
955 | /* An absolute destination. Start the loop from the beginning, but use the root | |
956 | * directory as base. */ | |
957 | ||
958 | safe_close(fd); | |
959 | fd = open(root ?: "/", O_CLOEXEC|O_NOFOLLOW|O_PATH); | |
960 | if (fd < 0) | |
961 | return -errno; | |
962 | ||
f14f1806 LP |
963 | if (flags & CHASE_SAFE) { |
964 | if (fstat(fd, &st) < 0) | |
965 | return -errno; | |
966 | ||
b85ee2ec | 967 | if (unsafe_transition(&previous_stat, &st)) |
fd74c6f3 | 968 | return log_unsafe_transition(child, fd, path, flags); |
f14f1806 LP |
969 | |
970 | previous_stat = st; | |
971 | } | |
972 | ||
b539437a YW |
973 | free(done); |
974 | ||
d944dc95 LP |
975 | /* Note that we do not revalidate the root, we take it as is. */ |
976 | if (isempty(root)) | |
977 | done = NULL; | |
978 | else { | |
979 | done = strdup(root); | |
980 | if (!done) | |
981 | return -ENOMEM; | |
982 | } | |
983 | ||
8c4a8ea2 LP |
984 | /* Prefix what's left to do with what we just read, and start the loop again, but |
985 | * remain in the current directory. */ | |
986 | joined = strjoin(destination, todo); | |
987 | } else | |
988 | joined = strjoin("/", destination, todo); | |
877777d7 CCW |
989 | if (!joined) |
990 | return -ENOMEM; | |
d944dc95 | 991 | |
877777d7 CCW |
992 | free(buffer); |
993 | todo = buffer = joined; | |
d944dc95 | 994 | |
49eb3659 LP |
995 | if (flags & CHASE_STEP) |
996 | goto chased_one; | |
997 | ||
d944dc95 LP |
998 | continue; |
999 | } | |
1000 | ||
1001 | /* If this is not a symlink, then let's just add the name we read to what we already verified. */ | |
ae2a15bc LP |
1002 | if (!done) |
1003 | done = TAKE_PTR(first); | |
1004 | else { | |
a1904a46 YW |
1005 | /* If done is "/", as first also contains slash at the head, then remove this redundant slash. */ |
1006 | if (streq(done, "/")) | |
1007 | *done = '\0'; | |
1008 | ||
d944dc95 LP |
1009 | if (!strextend(&done, first, NULL)) |
1010 | return -ENOMEM; | |
1011 | } | |
1012 | ||
1013 | /* And iterate again, but go one directory further down. */ | |
1014 | safe_close(fd); | |
c10d6bdb | 1015 | fd = TAKE_FD(child); |
d944dc95 LP |
1016 | } |
1017 | ||
1018 | if (!done) { | |
1019 | /* Special case, turn the empty string into "/", to indicate the root directory. */ | |
1020 | done = strdup("/"); | |
1021 | if (!done) | |
1022 | return -ENOMEM; | |
1023 | } | |
1024 | ||
ae2a15bc LP |
1025 | if (ret) |
1026 | *ret = TAKE_PTR(done); | |
d944dc95 | 1027 | |
1ed34d75 | 1028 | if (flags & CHASE_OPEN) { |
1ed34d75 LP |
1029 | /* Return the O_PATH fd we currently are looking to the caller. It can translate it to a proper fd by |
1030 | * opening /proc/self/fd/xyz. */ | |
1031 | ||
1032 | assert(fd >= 0); | |
c10d6bdb | 1033 | return TAKE_FD(fd); |
1ed34d75 LP |
1034 | } |
1035 | ||
49eb3659 LP |
1036 | if (flags & CHASE_STEP) |
1037 | return 1; | |
1038 | ||
a9fb0867 | 1039 | return exists; |
49eb3659 LP |
1040 | |
1041 | chased_one: | |
49eb3659 LP |
1042 | if (ret) { |
1043 | char *c; | |
1044 | ||
027cc9c9 ZJS |
1045 | c = strjoin(strempty(done), todo); |
1046 | if (!c) | |
1047 | return -ENOMEM; | |
49eb3659 LP |
1048 | |
1049 | *ret = c; | |
1050 | } | |
1051 | ||
1052 | return 0; | |
d944dc95 | 1053 | } |
57a4359e | 1054 | |
21c692e9 LP |
1055 | int chase_symlinks_and_open( |
1056 | const char *path, | |
1057 | const char *root, | |
1058 | unsigned chase_flags, | |
1059 | int open_flags, | |
1060 | char **ret_path) { | |
1061 | ||
1062 | _cleanup_close_ int path_fd = -1; | |
1063 | _cleanup_free_ char *p = NULL; | |
1064 | int r; | |
1065 | ||
1066 | if (chase_flags & CHASE_NONEXISTENT) | |
1067 | return -EINVAL; | |
1068 | ||
57ea45e1 | 1069 | if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { |
21c692e9 LP |
1070 | /* Shortcut this call if none of the special features of this call are requested */ |
1071 | r = open(path, open_flags); | |
1072 | if (r < 0) | |
1073 | return -errno; | |
1074 | ||
1075 | return r; | |
1076 | } | |
1077 | ||
1078 | path_fd = chase_symlinks(path, root, chase_flags|CHASE_OPEN, ret_path ? &p : NULL); | |
1079 | if (path_fd < 0) | |
1080 | return path_fd; | |
1081 | ||
1082 | r = fd_reopen(path_fd, open_flags); | |
1083 | if (r < 0) | |
1084 | return r; | |
1085 | ||
1086 | if (ret_path) | |
1087 | *ret_path = TAKE_PTR(p); | |
1088 | ||
1089 | return r; | |
1090 | } | |
1091 | ||
1092 | int chase_symlinks_and_opendir( | |
1093 | const char *path, | |
1094 | const char *root, | |
1095 | unsigned chase_flags, | |
1096 | char **ret_path, | |
1097 | DIR **ret_dir) { | |
1098 | ||
1099 | char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; | |
1100 | _cleanup_close_ int path_fd = -1; | |
1101 | _cleanup_free_ char *p = NULL; | |
1102 | DIR *d; | |
1103 | ||
1104 | if (!ret_dir) | |
1105 | return -EINVAL; | |
1106 | if (chase_flags & CHASE_NONEXISTENT) | |
1107 | return -EINVAL; | |
1108 | ||
57ea45e1 | 1109 | if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { |
21c692e9 LP |
1110 | /* Shortcut this call if none of the special features of this call are requested */ |
1111 | d = opendir(path); | |
1112 | if (!d) | |
1113 | return -errno; | |
1114 | ||
1115 | *ret_dir = d; | |
1116 | return 0; | |
1117 | } | |
1118 | ||
1119 | path_fd = chase_symlinks(path, root, chase_flags|CHASE_OPEN, ret_path ? &p : NULL); | |
1120 | if (path_fd < 0) | |
1121 | return path_fd; | |
1122 | ||
1123 | xsprintf(procfs_path, "/proc/self/fd/%i", path_fd); | |
1124 | d = opendir(procfs_path); | |
1125 | if (!d) | |
1126 | return -errno; | |
1127 | ||
1128 | if (ret_path) | |
1129 | *ret_path = TAKE_PTR(p); | |
1130 | ||
1131 | *ret_dir = d; | |
1132 | return 0; | |
1133 | } | |
1134 | ||
d2bcd0ba LP |
1135 | int chase_symlinks_and_stat( |
1136 | const char *path, | |
1137 | const char *root, | |
1138 | unsigned chase_flags, | |
1139 | char **ret_path, | |
1140 | struct stat *ret_stat) { | |
1141 | ||
1142 | _cleanup_close_ int path_fd = -1; | |
1143 | _cleanup_free_ char *p = NULL; | |
1144 | ||
1145 | assert(path); | |
1146 | assert(ret_stat); | |
1147 | ||
1148 | if (chase_flags & CHASE_NONEXISTENT) | |
1149 | return -EINVAL; | |
1150 | ||
1151 | if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { | |
1152 | /* Shortcut this call if none of the special features of this call are requested */ | |
1153 | if (stat(path, ret_stat) < 0) | |
1154 | return -errno; | |
1155 | ||
1156 | return 1; | |
1157 | } | |
1158 | ||
1159 | path_fd = chase_symlinks(path, root, chase_flags|CHASE_OPEN, ret_path ? &p : NULL); | |
1160 | if (path_fd < 0) | |
1161 | return path_fd; | |
1162 | ||
1163 | if (fstat(path_fd, ret_stat) < 0) | |
1164 | return -errno; | |
1165 | ||
1166 | if (ret_path) | |
1167 | *ret_path = TAKE_PTR(p); | |
1168 | ||
1169 | if (chase_flags & CHASE_OPEN) | |
1170 | return TAKE_FD(path_fd); | |
1171 | ||
1172 | return 1; | |
1173 | } | |
1174 | ||
57a4359e | 1175 | int access_fd(int fd, int mode) { |
fbd0b64f | 1176 | char p[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(fd) + 1]; |
57a4359e LP |
1177 | int r; |
1178 | ||
1179 | /* Like access() but operates on an already open fd */ | |
1180 | ||
1181 | xsprintf(p, "/proc/self/fd/%i", fd); | |
57a4359e LP |
1182 | r = access(p, mode); |
1183 | if (r < 0) | |
21c692e9 | 1184 | return -errno; |
57a4359e LP |
1185 | |
1186 | return r; | |
1187 | } | |
43767d9d | 1188 | |
627d2bac ZJS |
1189 | void unlink_tempfilep(char (*p)[]) { |
1190 | /* If the file is created with mkstemp(), it will (almost always) | |
1191 | * change the suffix. Treat this as a sign that the file was | |
1192 | * successfully created. We ignore both the rare case where the | |
1193 | * original suffix is used and unlink failures. */ | |
1194 | if (!endswith(*p, ".XXXXXX")) | |
69821560 | 1195 | (void) unlink_noerrno(*p); |
627d2bac ZJS |
1196 | } |
1197 | ||
43767d9d LP |
1198 | int unlinkat_deallocate(int fd, const char *name, int flags) { |
1199 | _cleanup_close_ int truncate_fd = -1; | |
1200 | struct stat st; | |
1201 | off_t l, bs; | |
1202 | ||
1203 | /* Operates like unlinkat() but also deallocates the file contents if it is a regular file and there's no other | |
1204 | * link to it. This is useful to ensure that other processes that might have the file open for reading won't be | |
1205 | * able to keep the data pinned on disk forever. This call is particular useful whenever we execute clean-up | |
1206 | * jobs ("vacuuming"), where we want to make sure the data is really gone and the disk space released and | |
1207 | * returned to the free pool. | |
1208 | * | |
1209 | * Deallocation is preferably done by FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE (👊) if supported, which means | |
1210 | * the file won't change size. That's a good thing since we shouldn't needlessly trigger SIGBUS in other | |
1211 | * programs that have mmap()ed the file. (The assumption here is that changing file contents to all zeroes | |
1212 | * underneath those programs is the better choice than simply triggering SIGBUS in them which truncation does.) | |
1213 | * However if hole punching is not implemented in the kernel or file system we'll fall back to normal file | |
1214 | * truncation (🔪), as our goal of deallocating the data space trumps our goal of being nice to readers (💐). | |
1215 | * | |
1216 | * Note that we attempt deallocation, but failure to succeed with that is not considered fatal, as long as the | |
1217 | * primary job – to delete the file – is accomplished. */ | |
1218 | ||
1219 | if ((flags & AT_REMOVEDIR) == 0) { | |
1220 | truncate_fd = openat(fd, name, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_NONBLOCK); | |
1221 | if (truncate_fd < 0) { | |
1222 | ||
1223 | /* If this failed because the file doesn't exist propagate the error right-away. Also, | |
1224 | * AT_REMOVEDIR wasn't set, and we tried to open the file for writing, which means EISDIR is | |
1225 | * returned when this is a directory but we are not supposed to delete those, hence propagate | |
1226 | * the error right-away too. */ | |
1227 | if (IN_SET(errno, ENOENT, EISDIR)) | |
1228 | return -errno; | |
1229 | ||
1230 | if (errno != ELOOP) /* don't complain if this is a symlink */ | |
1231 | log_debug_errno(errno, "Failed to open file '%s' for deallocation, ignoring: %m", name); | |
1232 | } | |
1233 | } | |
1234 | ||
1235 | if (unlinkat(fd, name, flags) < 0) | |
1236 | return -errno; | |
1237 | ||
1238 | if (truncate_fd < 0) /* Don't have a file handle, can't do more ☹️ */ | |
1239 | return 0; | |
1240 | ||
1241 | if (fstat(truncate_fd, &st) < 0) { | |
011723a4 | 1242 | log_debug_errno(errno, "Failed to stat file '%s' for deallocation, ignoring: %m", name); |
43767d9d LP |
1243 | return 0; |
1244 | } | |
1245 | ||
1246 | if (!S_ISREG(st.st_mode) || st.st_blocks == 0 || st.st_nlink > 0) | |
1247 | return 0; | |
1248 | ||
1249 | /* If this is a regular file, it actually took up space on disk and there are no other links it's time to | |
1250 | * punch-hole/truncate this to release the disk space. */ | |
1251 | ||
1252 | bs = MAX(st.st_blksize, 512); | |
1253 | l = DIV_ROUND_UP(st.st_size, bs) * bs; /* Round up to next block size */ | |
1254 | ||
1255 | if (fallocate(truncate_fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE, 0, l) >= 0) | |
1256 | return 0; /* Successfully punched a hole! 😊 */ | |
1257 | ||
1258 | /* Fall back to truncation */ | |
1259 | if (ftruncate(truncate_fd, 0) < 0) { | |
1260 | log_debug_errno(errno, "Failed to truncate file to 0, ignoring: %m"); | |
1261 | return 0; | |
1262 | } | |
1263 | ||
1264 | return 0; | |
1265 | } | |
11b29a96 LP |
1266 | |
1267 | int fsync_directory_of_file(int fd) { | |
0c462ea4 | 1268 | _cleanup_free_ char *path = NULL; |
11b29a96 LP |
1269 | _cleanup_close_ int dfd = -1; |
1270 | int r; | |
1271 | ||
1272 | r = fd_verify_regular(fd); | |
1273 | if (r < 0) | |
1274 | return r; | |
1275 | ||
1276 | r = fd_get_path(fd, &path); | |
3ceae1bc | 1277 | if (r < 0) { |
b8b846d7 LP |
1278 | log_debug_errno(r, "Failed to query /proc/self/fd/%d%s: %m", |
1279 | fd, | |
1280 | r == -EOPNOTSUPP ? ", ignoring" : ""); | |
3ceae1bc ZJS |
1281 | |
1282 | if (r == -EOPNOTSUPP) | |
1283 | /* If /proc is not available, we're most likely running in some | |
1284 | * chroot environment, and syncing the directory is not very | |
1285 | * important in that case. Let's just silently do nothing. */ | |
1286 | return 0; | |
1287 | ||
11b29a96 | 1288 | return r; |
3ceae1bc | 1289 | } |
11b29a96 LP |
1290 | |
1291 | if (!path_is_absolute(path)) | |
1292 | return -EINVAL; | |
1293 | ||
0c462ea4 | 1294 | dfd = open_parent(path, O_CLOEXEC, 0); |
11b29a96 | 1295 | if (dfd < 0) |
0c462ea4 | 1296 | return dfd; |
11b29a96 LP |
1297 | |
1298 | if (fsync(dfd) < 0) | |
1299 | return -errno; | |
1300 | ||
1301 | return 0; | |
1302 | } | |
ef8becfa | 1303 | |
36695e88 LP |
1304 | int fsync_path_at(int at_fd, const char *path) { |
1305 | _cleanup_close_ int opened_fd = -1; | |
1306 | int fd; | |
1307 | ||
1308 | if (isempty(path)) { | |
1309 | if (at_fd == AT_FDCWD) { | |
1310 | opened_fd = open(".", O_RDONLY|O_DIRECTORY|O_CLOEXEC); | |
1311 | if (opened_fd < 0) | |
1312 | return -errno; | |
1313 | ||
1314 | fd = opened_fd; | |
1315 | } else | |
1316 | fd = at_fd; | |
1317 | } else { | |
1318 | ||
1319 | opened_fd = openat(at_fd, path, O_RDONLY|O_CLOEXEC); | |
1320 | if (opened_fd < 0) | |
1321 | return -errno; | |
1322 | ||
1323 | fd = opened_fd; | |
1324 | } | |
1325 | ||
1326 | if (fsync(fd) < 0) | |
1327 | return -errno; | |
1328 | ||
1329 | return 0; | |
1330 | } | |
1331 | ||
ef8becfa LP |
1332 | int open_parent(const char *path, int flags, mode_t mode) { |
1333 | _cleanup_free_ char *parent = NULL; | |
1334 | int fd; | |
1335 | ||
1336 | if (isempty(path)) | |
1337 | return -EINVAL; | |
1338 | if (path_equal(path, "/")) /* requesting the parent of the root dir is fishy, let's prohibit that */ | |
1339 | return -EINVAL; | |
1340 | ||
1341 | parent = dirname_malloc(path); | |
1342 | if (!parent) | |
1343 | return -ENOMEM; | |
1344 | ||
1345 | /* Let's insist on O_DIRECTORY since the parent of a file or directory is a directory. Except if we open an | |
1346 | * O_TMPFILE file, because in that case we are actually create a regular file below the parent directory. */ | |
1347 | ||
1348 | if ((flags & O_PATH) == O_PATH) | |
1349 | flags |= O_DIRECTORY; | |
1350 | else if ((flags & O_TMPFILE) != O_TMPFILE) | |
1351 | flags |= O_DIRECTORY|O_RDONLY; | |
1352 | ||
1353 | fd = open(parent, flags, mode); | |
1354 | if (fd < 0) | |
1355 | return -errno; | |
1356 | ||
1357 | return fd; | |
1358 | } |