4 * @brief The adacl (apply default acl) shared library.
8 /* Enables get_current_dir_name() in unistd.h, the O_PATH flag, and
9 * the asprintf() function.
13 #include <dirent.h> /* readdir(), etc. */
14 #include <errno.h> /* EINVAL, ELOOP, ENOTDIR, etc. */
15 #include <fcntl.h> /* openat() */
16 #include <libgen.h> /* basename(), dirname() */
17 #include <stdbool.h> /* the "bool" type */
18 #include <stdio.h> /* perror(), asprintf() */
19 #include <stdlib.h> /* free() */
20 #include <string.h> /* strdup() */
21 #include <sys/stat.h> /* fstat() */
22 #include <sys/xattr.h> /* fgetxattr(), fsetxattr() */
23 #include <unistd.h> /* get_current_dir_name() */
26 #include <acl/libacl.h> /* acl_get_perm, not portable */
27 #include <sys/acl.h> /* all other acl_foo functions */
29 /* XATTR_NAME_POSIX_ACL_ACCESS and XATTR_NAME_POSIX_ACL_DEFAULT */
30 #include <linux/xattr.h>
35 /* Even though most other library functions reliably return -1 for
36 * error, it feels a little wrong to re-use the ACL_ERROR constant.
38 #define CLOSE_ERROR -1
40 #define ASPRINTF_ERROR -1
42 #define XATTR_ERROR -1
46 int safe_open_ex(int at_fd
, char* pathname
, int flags
);
47 int safe_open(const char* pathname
, int flags
);
48 int acl_update_entry(acl_t aclp
, acl_entry_t entry
);
49 int acl_entry_count(acl_t acl
);
50 int acl_is_minimal(acl_t acl
);
51 int acl_execute_masked(acl_t acl
);
52 int any_can_execute(int fd
, const struct stat
* sp
);
53 int acl_copy_xattr(int src_fd
,
57 int has_default_acl_fd(int fd
);
58 int apply_default_acl_fds(int parent_fd
, int fd
, bool recursive
);
59 int apply_default_acl(const char* path
, bool recursive
);
64 * @brief The recursive portion of the @c safe_open function, used to
65 * open a file descriptor in a symlink-safe way when combined with
66 * the @c O_NOFOLLOW flag.
69 * A file descriptor relative to which @c pathname will be opened.
72 * The path to the file/directory/whatever whose descriptor you want.
75 * File status flags to be passed to @c openat.
77 * @return a file descriptor for @c pathname if everything goes well,
78 * and @c OPEN_ERROR if not.
80 int safe_open_ex(int at_fd
, char* pathname
, int flags
) {
81 if (pathname
== NULL
) {
83 perror("safe_open_ex (args)");
87 char* firstslash
= strchr(pathname
, '/');
88 if (firstslash
== NULL
) {
89 /* No more slashes, this is the base case. */
90 return openat(at_fd
, pathname
, flags
);
92 if (firstslash
[1] == '\0') {
93 /* The first slash is the last character; ensure that we open
96 return openat(at_fd
, pathname
, flags
| O_DIRECTORY
);
99 /* The first slash exists and isn't the last character in the path,
100 so we can split the path wherever that first slash lies and
103 int fd
= openat(at_fd
, pathname
, flags
| O_DIRECTORY
| O_PATH
);
104 if (fd
== OPEN_ERROR
) {
105 if (errno
!= ENOTDIR
) {
106 /* Don't output anything if we ignore a symlink */
107 perror("safe_open_ex (safe_open_ex)");
112 /* The +1 is safe because there needs to be at least one character
113 after the first slash (we checked this above). */
114 int result
= safe_open_ex(fd
, firstslash
+1, flags
);
115 if (close(fd
) == CLOSE_ERROR
) {
116 perror("safe_open_ex (close)");
124 * @brief A version of @c open that is completely symlink-safe when
125 * used with the @c O_NOFOLLOW flag.
127 * The @c openat function exists to ensure that you can anchor one
128 * path to a particular directory while opening it; however, if you
129 * open "b/c/d" relative to "/a", then even the @c openat function will
130 * still follow symlinks in the "b" component. This can be exploited
131 * by an attacker to make you open the wrong path.
133 * To avoid that problem, this function uses a recursive
134 * implementation that opens every path from the root, one level at a
135 * time. So "a" is opened relative to "/", and then "b" is opened
136 * relative to "/a", and then "c" is opened relative to "/a/b",
137 * etc. When the @c O_NOFOLLOW flag is used, this approach ensures
138 * that no symlinks in any component are followed.
141 * The path to the file/directory/whatever whose descriptor you want.
144 * File status flags to be passed to @c openat.
146 * @return a file descriptor for @c pathname if everything goes well,
147 * and @c OPEN_ERROR if not.
149 int safe_open(const char* pathname
, int flags
) {
150 if (pathname
== NULL
) {
152 perror("safe_open (args)");
156 char* abspath
= NULL
;
157 int asprintf_result
= 0;
158 if (strchr(pathname
, '/') == pathname
) {
159 /* pathname is already absolute; just copy it. */
160 asprintf_result
= asprintf(&abspath
, "%s", pathname
);
163 /* Concatenate the current working directory and pathname into an
164 * absolute path. We use realpath() ONLY on the cwd part, and not
165 * on the pathname part, because realpath() resolves symlinks. And
166 * the whole point of all this crap is to avoid following symlinks
169 * Using realpath() on the cwd lets us operate on relative paths
170 * while we're sitting in a directory that happens to have a
171 * symlink in it; for example: cd /var/run && apply-default-acl foo.
173 char* cwd
= get_current_dir_name();
175 perror("safe_open (get_current_dir_name)");
179 char abs_cwd
[PATH_MAX
];
180 if (realpath(cwd
, abs_cwd
) == NULL
) {
181 perror("safe_open (realpath)");
185 asprintf_result
= asprintf(&abspath
, "%s/%s", abs_cwd
, pathname
);
188 if (asprintf_result
== ASPRINTF_ERROR
) {
189 perror("safe_open (asprintf)");
193 /* Beyond here, asprintf() worked, and we need to free abspath. */
194 int result
= OPEN_ERROR
;
196 bool abspath_is_root
= (strcmp(abspath
, "/") == 0);
197 int rootflags
= flags
| O_DIRECTORY
;
198 if (!abspath_is_root
) {
199 /* Use O_PATH for some added safety if "/" is not our target */
202 int rootfd
= open("/", rootflags
);
203 if (rootfd
== OPEN_ERROR
) {
204 perror("safe_open (open)");
209 if (abspath_is_root
) {
214 result
= safe_open_ex(rootfd
, abspath
+1, flags
);
215 if (close(rootfd
) == CLOSE_ERROR
) {
216 perror("safe_open (close)");
230 * @brief Update an entry in an @b minimal ACL.
233 * A pointer to the acl_t structure whose entry we want to update.
239 * - @c ACL_SUCCESS - If we update an existing entry.
240 * - @c ACL_FAILURE - If we don't find an entry to update.
241 * - @c ACL_ERROR - Unexpected library error.
243 int acl_update_entry(acl_t aclp
, acl_entry_t entry
) {
244 if (aclp
== NULL
|| entry
== NULL
) {
246 perror("acl_update_entry (args)");
251 if (acl_get_tag_type(entry
, &entry_tag
) == ACL_ERROR
) {
252 perror("acl_update_entry (acl_get_tag_type)");
256 acl_permset_t entry_permset
;
257 if (acl_get_permset(entry
, &entry_permset
) == ACL_ERROR
) {
258 perror("acl_update_entry (acl_get_permset)");
262 acl_entry_t existing_entry
;
263 /* Loop through the given ACL looking for matching entries. */
264 int result
= acl_get_entry(aclp
, ACL_FIRST_ENTRY
, &existing_entry
);
266 while (result
== ACL_SUCCESS
) {
267 acl_tag_t existing_tag
= ACL_UNDEFINED_TAG
;
269 if (acl_get_tag_type(existing_entry
, &existing_tag
) == ACL_ERROR
) {
270 perror("set_acl_tag_permset (acl_get_tag_type)");
274 if (existing_tag
== entry_tag
) {
275 /* If we update something, we're done and return ACL_SUCCESS */
276 if (acl_set_permset(existing_entry
, entry_permset
) == ACL_ERROR
) {
277 perror("acl_update_entry (acl_set_permset)");
284 result
= acl_get_entry(aclp
, ACL_NEXT_ENTRY
, &existing_entry
);
287 /* This catches both the initial acl_get_entry and the ones at the
289 if (result
== ACL_ERROR
) {
290 perror("acl_update_entry (acl_get_entry)");
300 * @brief Determine the number of entries in the given ACL.
303 * The ACL to inspect.
305 * @return Either the non-negative number of entries in @c acl, or
306 * @c ACL_ERROR on error.
308 int acl_entry_count(acl_t acl
) {
312 int result
= acl_get_entry(acl
, ACL_FIRST_ENTRY
, &entry
);
314 while (result
== ACL_SUCCESS
) {
316 result
= acl_get_entry(acl
, ACL_NEXT_ENTRY
, &entry
);
319 if (result
== ACL_ERROR
) {
320 perror("acl_entry_count (acl_get_entry)");
330 * @brief Determine whether or not the given ACL is minimal.
332 * An ACL is minimal if it has fewer than four entries.
335 * The ACL whose minimality is in question.
338 * - @c ACL_SUCCESS - @c acl is minimal
339 * - @c ACL_FAILURE - @c acl is not minimal
340 * - @c ACL_ERROR - Unexpected library error
342 int acl_is_minimal(acl_t acl
) {
345 perror("acl_is_minimal (args)");
349 int ec
= acl_entry_count(acl
);
351 if (ec
== ACL_ERROR
) {
352 perror("acl_is_minimal (acl_entry_count)");
367 * @brief Determine whether the given ACL's mask denies execute.
370 * The ACL whose mask we want to check.
373 * - @c ACL_SUCCESS - The @c acl has a mask which denies execute.
374 * - @c ACL_FAILURE - The @c acl has a mask which does not deny execute.
375 * - @c ACL_ERROR - Unexpected library error.
377 int acl_execute_masked(acl_t acl
) {
380 perror("acl_execute_masked (args)");
385 int ge_result
= acl_get_entry(acl
, ACL_FIRST_ENTRY
, &entry
);
387 while (ge_result
== ACL_SUCCESS
) {
388 acl_tag_t tag
= ACL_UNDEFINED_TAG
;
390 if (acl_get_tag_type(entry
, &tag
) == ACL_ERROR
) {
391 perror("acl_execute_masked (acl_get_tag_type)");
395 if (tag
== ACL_MASK
) {
396 /* This is the mask entry, get its permissions, and see if
397 execute is specified. */
398 acl_permset_t permset
;
400 if (acl_get_permset(entry
, &permset
) == ACL_ERROR
) {
401 perror("acl_execute_masked (acl_get_permset)");
405 int gp_result
= acl_get_perm(permset
, ACL_EXECUTE
);
406 if (gp_result
== ACL_ERROR
) {
407 perror("acl_execute_masked (acl_get_perm)");
411 if (gp_result
== ACL_FAILURE
) {
412 /* No execute bit set in the mask; execute not allowed. */
417 ge_result
= acl_get_entry(acl
, ACL_NEXT_ENTRY
, &entry
);
426 * @brief Determine whether @c fd is executable by anyone.
429 * This is used as part of the heuristic to determine whether or not
430 * we should mask the execute bit when inheriting an ACL. If @c fd
431 * describes a file, we check the @a effective permissions, contrary
432 * to what setfacl does.
435 * The file descriptor to check.
438 * A pointer to a stat structure for @c fd.
441 * - @c ACL_SUCCESS - Someone has effective execute permissions on @c fd.
442 * - @c ACL_FAILURE - Nobody can execute @c fd.
443 * - @c ACL_ERROR - Unexpected library error.
445 int any_can_execute(int fd
, const struct stat
* sp
) {
448 perror("any_can_execute (args)");
452 acl_t acl
= acl_get_fd(fd
);
454 if (acl
== (acl_t
)NULL
) {
455 perror("any_can_execute (acl_get_fd)");
459 /* Our return value. */
460 int result
= ACL_FAILURE
;
462 if (acl_is_minimal(acl
)) {
463 if (sp
->st_mode
& (S_IXUSR
| S_IXOTH
| S_IXGRP
)) {
464 result
= ACL_SUCCESS
;
468 result
= ACL_FAILURE
;
474 int ge_result
= acl_get_entry(acl
, ACL_FIRST_ENTRY
, &entry
);
476 while (ge_result
== ACL_SUCCESS
) {
477 /* The first thing we do is check to see if this is a mask
478 entry. If it is, we skip it entirely. */
479 acl_tag_t tag
= ACL_UNDEFINED_TAG
;
481 if (acl_get_tag_type(entry
, &tag
) == ACL_ERROR
) {
482 perror("any_can_execute_or (acl_get_tag_type)");
487 if (tag
== ACL_MASK
) {
488 ge_result
= acl_get_entry(acl
, ACL_NEXT_ENTRY
, &entry
);
492 /* Ok, so it's not a mask entry. Check the execute perms. */
493 acl_permset_t permset
;
495 if (acl_get_permset(entry
, &permset
) == ACL_ERROR
) {
496 perror("any_can_execute_or (acl_get_permset)");
501 int gp_result
= acl_get_perm(permset
, ACL_EXECUTE
);
502 if (gp_result
== ACL_ERROR
) {
503 perror("any_can_execute (acl_get_perm)");
508 if (gp_result
== ACL_SUCCESS
) {
509 /* Only return ACL_SUCCESS if this execute bit is not masked. */
510 if (acl_execute_masked(acl
) != ACL_SUCCESS
) {
511 result
= ACL_SUCCESS
;
516 ge_result
= acl_get_entry(acl
, ACL_NEXT_ENTRY
, &entry
);
519 if (ge_result
== ACL_ERROR
) {
520 perror("any_can_execute (acl_get_entry)");
533 * @brief Copy ACLs between file descriptors as xattrs, verbatim.
535 * There is a small deficiency in libacl, namely that there is no way
536 * to get or set default ACLs through file descriptors. The @c
537 * acl_get_file and @c acl_set_file functions can do it, but they use
538 * paths, and are vulnerable to symlink attacks.
540 * Fortunately, when inheriting an ACL, we don't really need to look
541 * at what it contains. That means that we can copy the on-disk xattrs
542 * from the source directory to the destination file/directory without
543 * passing through libacl, and this can be done with file descriptors
544 * through @c fgetxattr and @c fsetxattr. That's what this function
548 * The file descriptor from which the ACL will be copied.
551 * The type of ACL (either @c ACL_TYPE_ACCESS or @c ACL_TYPE_DEFAULT)
552 * to copy from @c src_fd.
555 * The file descriptor whose ACL will be overwritten with the one
559 * The type of ACL (either @c ACL_TYPE_ACCESS or @c ACL_TYPE_DEFAULT)
560 * to replace on @c dst_fd.
563 * - @c ACL_SUCCESS - The ACL was copied successfully.
564 * - @c ACL_FAILURE - There was no ACL on @c src_fd.
565 * - @c ACL_ERROR - Unexpected library error.
567 int acl_copy_xattr(int src_fd
,
570 acl_type_t dst_type
) {
572 const char* src_name
;
573 if (src_type
== ACL_TYPE_ACCESS
) {
574 src_name
= XATTR_NAME_POSIX_ACL_ACCESS
;
576 else if (src_type
== ACL_TYPE_DEFAULT
) {
577 src_name
= XATTR_NAME_POSIX_ACL_DEFAULT
;
581 perror("acl_copy_xattr (src type)");
585 const char* dst_name
;
586 if (dst_type
== ACL_TYPE_ACCESS
) {
587 dst_name
= XATTR_NAME_POSIX_ACL_ACCESS
;
589 else if (dst_type
== ACL_TYPE_DEFAULT
) {
590 dst_name
= XATTR_NAME_POSIX_ACL_DEFAULT
;
594 perror("acl_copy_xattr (dst type)");
598 ssize_t src_size_guess
= fgetxattr(src_fd
, src_name
, NULL
, 0);
599 if (src_size_guess
== XATTR_ERROR
) {
600 if (errno
== ENODATA
) {
601 /* A missing ACL isn't really an error. ENOATTR and ENODATA are
602 synonyms, but using ENODATA here lets us avoid another
603 "include" directive. */
606 perror("acl_copy_xattr (fgetxattr size guess)");
609 char* src_acl_p
= alloca(src_size_guess
);
610 /* The actual size may be smaller than our guess? I don't know. */
611 ssize_t src_size
= fgetxattr(src_fd
, src_name
, src_acl_p
, src_size_guess
);
612 if (src_size
== XATTR_ERROR
) {
613 if (errno
== ENODATA
) {
614 /* A missing ACL isn't an error. */
617 perror("acl_copy_xattr (fgetxattr)");
621 if (fsetxattr(dst_fd
, dst_name
, src_acl_p
, src_size
, 0) == XATTR_ERROR
) {
622 perror("acl_copy_xattr (fsetxattr)");
631 * @brief Determine if a file descriptor has a default ACL.
634 * The file descriptor whose default ACL is in question.
637 * - @c ACL_SUCCESS - If @c fd has a default ACL.
638 * - @c ACL_FAILURE - If @c fd does not have a default ACL.
639 * - @c ACL_ERROR - Unexpected library error.
641 int has_default_acl_fd(int fd
) {
642 if (fgetxattr(fd
, XATTR_NAME_POSIX_ACL_DEFAULT
, NULL
, 0) == XATTR_ERROR
) {
643 if (errno
== ENODATA
) {
646 perror("has_default_acl_fd (fgetxattr)");
656 * @brief The recursive portion of @c apply_default_acl.
658 * The @c apply_default_acl function takes a path, but then opens file
659 * descriptors for the path and its parent. Afterwards, everything is
660 * done using file descriptors, including the recursive application on
661 * the path's children. This function encapsulates the portion of @c
662 * apply_default_acl that uses only file descriptors; for the
663 * recursion, this function ultimately calls itself.
665 * This overwrites any existing ACLs on @c fd and, if @c recursive is
666 * @c true, its children. When @c recursive is @c true, the "worst"
667 * result encountered is returned as the overall result.
670 * A file descriptor for the parent directory of @c fd.
673 * The file descriptor that should inherit its parent's default ACL.
676 * Should we recurse into subdirectories?
679 * - @c ACL_SUCCESS - The parent default ACLs were inherited successfully.
680 * - @c ACL_FAILURE - If symlinks or hard links are encountered.
681 * - @c ACL_ERROR - Unexpected library error.
683 int apply_default_acl_fds(int parent_fd
,
686 int result
= ACL_SUCCESS
;
688 /* The new ACL for this path */
689 acl_t new_acl
= (acl_t
)NULL
;
691 /* A copy of new_acl, to be made before we begin mangling new_acl in
692 order to mask the execute bit. */
693 acl_t new_acl_unmasked
= (acl_t
)NULL
;
695 /* Refuse to operate on hard links, which can be abused by an
696 * attacker to trick us into changing the ACL on a file we didn't
697 * intend to; namely the "target" of the hard link. There is TOCTOU
698 * race condition here, but the window is as small as possible
699 * between when we open the file descriptor (look above) and when we
703 if (fstat(fd
, &s
) == STAT_ERROR
) {
704 perror("apply_default_acl_fds (fstat)");
705 /* We can't recurse without the stat struct for fd */
710 /* Check to make sure the parent descriptor actually has a default
711 ACL. If it doesn't, then we can "succeed" immediately, saving a
712 little work, particularly in any_can_execute(). Note that we
713 can't skip the fstat() above, because we need it in case we
715 if (has_default_acl_fd(parent_fd
) == ACL_FAILURE
) {
716 result
= ACL_SUCCESS
;
717 /* Just because this target can't inherit anything doesn't mean
718 that one of it's children can't. For example, if there's a
719 default on "c" in "a/b/c/d", then we don't want to skip all
725 if (!S_ISDIR(s
.st_mode
)) {
726 /* If it's not a directory, make sure it's a regular,
727 non-hard-linked file. */
728 if (!S_ISREG(s
.st_mode
) || s
.st_nlink
!= 1) {
729 result
= ACL_FAILURE
;
730 goto cleanup
; /* It's not a directory, so we can skip the recursion. */
735 /* Next We try to guess whether or not to strip the execute bits.
736 * This behavior is modeled after the capital 'X' perms of setfacl.
738 int ace_result
= any_can_execute(fd
, &s
);
740 if (ace_result
== ACL_ERROR
) {
741 perror("apply_default_acl_fds (any_can_execute)");
746 /* Never mask the execute bit on directories. */
747 bool allow_exec
= (bool)ace_result
|| S_ISDIR(s
.st_mode
);
750 /* If it's a directory, inherit the parent's default. */
751 if (S_ISDIR(s
.st_mode
)) {
752 if (acl_copy_xattr(parent_fd
,
755 ACL_TYPE_DEFAULT
) == ACL_ERROR
) {
756 perror("apply_default_acl_fds (acl_copy_xattr default)");
762 /* If it's anything, _apply_ the parent's default. */
763 if (acl_copy_xattr(parent_fd
,
766 ACL_TYPE_ACCESS
) == ACL_ERROR
) {
767 perror("apply_default_acl_fds (acl_copy_xattr access)");
772 /* There's a good reason why we saved the ACL above, even though
773 * we're about to read it back into memory and mess with it on the
774 * next line. The acl_copy_xattr() function is already a hack to let
775 * us copy default ACLs without resorting to path names; we simply
776 * have no way to read the parent's default ACL into memory using
777 * parent_fd. We can, however, copy the parent's ACL to a file (with
778 * acl_copy_xattr), and then read the ACL from a file using
779 * "fd". It's quite the circus, but it works and should be safe from
780 * sym/hardlink attacks.
783 /* Now we potentially need to mask the execute permissions in the
784 ACL on fd; or maybe not. */
786 /* Skip the mask code for this target, but don't skip its children! */
790 /* OK, we need to mask some execute permissions. First obtain the
792 new_acl
= acl_get_fd(fd
);
793 if (new_acl
== (acl_t
)NULL
) {
794 perror("apply_default_acl_fds (acl_get_fd)");
799 /* ...and now make a copy of it, because otherwise when we loop
800 below, some shit gets stuck (modifying the structure while
801 looping over it no worky). */
802 new_acl_unmasked
= acl_dup(new_acl
);
803 if (new_acl_unmasked
== (acl_t
)NULL
) {
804 perror("apply_default_acl_fds (acl_dup)");
810 int ge_result
= acl_get_entry(new_acl_unmasked
, ACL_FIRST_ENTRY
, &entry
);
812 while (ge_result
== ACL_SUCCESS
) {
813 acl_tag_t tag
= ACL_UNDEFINED_TAG
;
815 if (acl_get_tag_type(entry
, &tag
) == ACL_ERROR
) {
816 perror("apply_default_acl_fds (acl_get_tag_type)");
822 /* We've got an entry/tag from the default ACL. Get its permset. */
823 acl_permset_t permset
;
824 if (acl_get_permset(entry
, &permset
) == ACL_ERROR
) {
825 perror("apply_default_acl_fds (acl_get_permset)");
830 /* To mimic what the kernel does, I think we could drop
831 ACL_GROUP_OBJ from the list below? */
832 if (tag
== ACL_MASK
||
833 tag
== ACL_USER_OBJ
||
834 tag
== ACL_GROUP_OBJ
||
837 /* The mask doesn't affect acl_user_obj, acl_group_obj (in
838 minimal ACLs) or acl_other entries, so if execute should be
839 masked, we have to do it manually. */
840 if (acl_delete_perm(permset
, ACL_EXECUTE
) == ACL_ERROR
) {
841 perror("apply_default_acl_fds (acl_delete_perm)");
846 if (acl_set_permset(entry
, permset
) == ACL_ERROR
) {
847 perror("apply_default_acl_fds (acl_set_permset)");
853 if (acl_update_entry(new_acl
, entry
) == ACL_ERROR
) {
854 perror("apply_default_acl_fds (acl_update_entry)");
859 ge_result
= acl_get_entry(new_acl_unmasked
, ACL_NEXT_ENTRY
, &entry
);
862 /* Catches the first acl_get_entry as well as the ones at the end of
864 if (ge_result
== ACL_ERROR
) {
865 perror("apply_default_acl_fds (acl_get_entry)");
870 if (acl_set_fd(fd
, new_acl
) == ACL_ERROR
) {
871 perror("apply_default_acl_fds (acl_set_fd)");
877 if (recursive
&& S_ISDIR(s
.st_mode
)) {
878 /* Recurse into subdirectories. Don't call closedir() on d! It
879 closes the open file descriptor as well, and subsequent calls
880 to close() then throw errors. */
881 DIR* d
= fdopendir(fd
);
883 perror("apply_default_acl_fds (fdopendir)");
890 while ((de
= readdir(d
)) != NULL
) {
891 if (de
->d_type
!= DT_DIR
&& de
->d_type
!= DT_REG
) {
892 /* Hit a symlink or whatever. */
893 result
= ACL_FAILURE
;
896 if (strcmp(de
->d_name
, ".") == 0) { continue; }
897 if (strcmp(de
->d_name
, "..") == 0) { continue; }
899 /* Be careful not to "return" out of this loop and leave the
901 new_fd
= openat(fd
, de
->d_name
, O_NOFOLLOW
);
902 if (new_fd
== OPEN_ERROR
) {
903 if (errno
== ELOOP
|| errno
== ENOTDIR
) {
904 /* We hit a symlink, either in the last path component (ELOOP)
905 or higher up (ENOTDIR). */
906 if (result
== ACL_SUCCESS
) {
907 /* Don't overwrite an error result with success/failure. */
908 result
= ACL_FAILURE
;
913 perror("apply_default_acl_fds (openat)");
918 switch (apply_default_acl_fds(fd
, new_fd
, recursive
)) {
919 /* Don't overwrite an error result with success/failure. */
921 if (result
== ACL_SUCCESS
) {
922 result
= ACL_FAILURE
;
928 if (close(new_fd
) == CLOSE_ERROR
) {
929 perror("apply_default_acl_fds (close)");
938 acl_free(new_acl_unmasked
);
944 * @brief Apply parent default ACL to a path and optionally its children.
946 * This overwrites any existing ACLs on the target, and, if @c
947 * recursive is @c true, its children. When @c recursive is @c true,
948 * the "worst" result encountered is returned as the overall result.
951 * The path whose ACL we would like to reset to its default.
954 * Should we recurse into subdirectories?
957 * - @c ACL_SUCCESS - The parent default ACLs were inherited successfully.
958 * - @c ACL_FAILURE - If symlinks or hard links are encountered.
959 * - @c ACL_ERROR - Unexpected library error.
961 int apply_default_acl(const char* path
, bool recursive
) {
965 perror("apply_default_acl (args)");
969 /* Define these next three variables here because we may have to
970 * jump to the cleanup routine which expects them to exist.
973 /* Our return value. */
974 int result
= ACL_SUCCESS
;
976 /* The file descriptor corresponding to "path" */
979 /* The file descriptor for the directory containing "path" */
982 /* dirname() and basename() mangle their arguments, so we need
983 to make copies of "path" before using them. */
984 char* dirname_path_copy
= NULL
;
985 char* basename_path_copy
= NULL
;
987 /* Get the parent directory of "path" with dirname(), which happens
988 * to murder its argument and necessitates a path_copy. */
989 dirname_path_copy
= strdup(path
);
990 if (dirname_path_copy
== NULL
) {
991 perror("apply_default_acl (strdup)");
994 char* parent
= dirname(dirname_path_copy
);
995 parent_fd
= safe_open(parent
, O_DIRECTORY
| O_NOFOLLOW
);
996 if (parent_fd
== OPEN_ERROR
) {
997 if (errno
== ELOOP
|| errno
== ENOTDIR
) {
998 /* We hit a symlink, either in the last path component (ELOOP)
999 or higher up (ENOTDIR). */
1000 result
= ACL_FAILURE
;
1004 perror("apply_default_acl (open parent fd)");
1010 /* We already obtained the parent fd safely, so if we use the
1011 basename of path here instead of the full thing, then we can get
1012 away with using openat() and spare ourselves the slowness of
1013 another safe_open(). */
1014 basename_path_copy
= strdup(path
);
1015 if (basename_path_copy
== NULL
) {
1016 perror("apply_default_acl (strdup)");
1019 fd
= openat(parent_fd
, basename(basename_path_copy
), O_NOFOLLOW
);
1020 if (fd
== OPEN_ERROR
) {
1021 if (errno
== ELOOP
|| errno
== ENOTDIR
) {
1022 /* We hit a symlink, either in the last path component (ELOOP)
1023 or higher up (ENOTDIR). */
1024 result
= ACL_FAILURE
;
1028 perror("apply_default_acl (open fd)");
1034 result
= apply_default_acl_fds(parent_fd
, fd
, recursive
);
1037 free(dirname_path_copy
);
1038 free(basename_path_copy
);
1040 if (parent_fd
> 0 && close(parent_fd
) == CLOSE_ERROR
) {
1041 perror("apply_default_acl (close parent_fd)");
1044 if (fd
> 0 && close(fd
) == CLOSE_ERROR
) {
1045 perror("apply_default_acl (close fd)");