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chown-recursive.c
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178 lines (140 loc) · 5.7 KB
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/xattr.h>
#include "chown-recursive.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "fs-util.h"
#include "macro.h"
#include "stdio-util.h"
#include "strv.h"
#include "user-util.h"
static int chown_one(
int fd,
const struct stat *st,
uid_t uid,
gid_t gid,
mode_t mask) {
char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
const char *n;
int r;
assert(fd >= 0);
assert(st);
/* We change ACLs through the /proc/self/fd/%i path, so that we have a stable reference that works
* with O_PATH. */
xsprintf(procfs_path, "/proc/self/fd/%i", fd);
/* Drop any ACL if there is one */
FOREACH_STRING(n, "system.posix_acl_access", "system.posix_acl_default")
if (removexattr(procfs_path, n) < 0)
if (!IN_SET(errno, ENODATA, EOPNOTSUPP, ENOSYS, ENOTTY))
return -errno;
r = fchmod_and_chown(fd, st->st_mode & mask, uid, gid);
if (r < 0)
return r;
return 1;
}
static int chown_recursive_internal(
int fd,
const struct stat *st,
uid_t uid,
gid_t gid,
mode_t mask) {
_cleanup_closedir_ DIR *d = NULL;
bool changed = false;
struct dirent *de;
int r;
assert(fd >= 0);
assert(st);
d = fdopendir(fd);
if (!d) {
safe_close(fd);
return -errno;
}
FOREACH_DIRENT_ALL(de, d, return -errno) {
_cleanup_close_ int path_fd = -1;
struct stat fst;
if (dot_or_dot_dot(de->d_name))
continue;
/* Let's pin the child inode we want to fix now with an O_PATH fd, so that it cannot be swapped out
* while we manipulate it. */
path_fd = openat(dirfd(d), de->d_name, O_PATH|O_CLOEXEC|O_NOFOLLOW);
if (path_fd < 0)
return -errno;
if (fstat(path_fd, &fst) < 0)
return -errno;
if (S_ISDIR(fst.st_mode)) {
int subdir_fd;
/* Convert it to a "real" (i.e. non-O_PATH) fd now */
subdir_fd = fd_reopen(path_fd, O_RDONLY|O_CLOEXEC|O_NOATIME);
if (subdir_fd < 0)
return subdir_fd;
r = chown_recursive_internal(subdir_fd, &fst, uid, gid, mask); /* takes possession of subdir_fd even on failure */
if (r < 0)
return r;
if (r > 0)
changed = true;
} else {
r = chown_one(path_fd, &fst, uid, gid, mask);
if (r < 0)
return r;
if (r > 0)
changed = true;
}
}
r = chown_one(dirfd(d), st, uid, gid, mask);
if (r < 0)
return r;
return r > 0 || changed;
}
int path_chown_recursive(
const char *path,
uid_t uid,
gid_t gid,
mode_t mask) {
_cleanup_close_ int fd = -1;
struct stat st;
fd = open(path, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
if (fd < 0)
return -errno;
if (!uid_is_valid(uid) && !gid_is_valid(gid) && FLAGS_SET(mask, 07777))
return 0; /* nothing to do */
if (fstat(fd, &st) < 0)
return -errno;
/* Let's take a shortcut: if the top-level directory is properly owned, we don't descend into the
* whole tree, under the assumption that all is OK anyway. */
if ((!uid_is_valid(uid) || st.st_uid == uid) &&
(!gid_is_valid(gid) || st.st_gid == gid) &&
((st.st_mode & ~mask & 07777) == 0))
return 0;
return chown_recursive_internal(TAKE_FD(fd), &st, uid, gid, mask); /* we donate the fd to the call, regardless if it succeeded or failed */
}
int fd_chown_recursive(
int fd,
uid_t uid,
gid_t gid,
mode_t mask) {
int duplicated_fd = -1;
struct stat st;
/* Note that the slightly different order of fstat() and the checks here and in
* path_chown_recursive(). That's because when we open the directory ourselves we can specify
* O_DIRECTORY and we always want to ensure we are operating on a directory before deciding whether
* the operation is otherwise redundant. */
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISDIR(st.st_mode))
return -ENOTDIR;
if (!uid_is_valid(uid) && !gid_is_valid(gid) && FLAGS_SET(mask, 07777))
return 0; /* nothing to do */
/* Shortcut, as above */
if ((!uid_is_valid(uid) || st.st_uid == uid) &&
(!gid_is_valid(gid) || st.st_gid == gid) &&
((st.st_mode & ~mask & 07777) == 0))
return 0;
/* Let's duplicate the fd here, as opendir() wants to take possession of it and close it afterwards */
duplicated_fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
if (duplicated_fd < 0)
return -errno;
return chown_recursive_internal(duplicated_fd, &st, uid, gid, mask); /* fd donated even on failure */
}