134 lines
4.7 KiB
C
134 lines
4.7 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/xattr.h>
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#include "chown-recursive.h"
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#include "dirent-util.h"
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#include "fd-util.h"
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#include "macro.h"
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#include "stdio-util.h"
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#include "strv.h"
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#include "user-util.h"
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static int chown_one(int fd, const struct stat *st, uid_t uid, gid_t gid) {
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char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
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const char *n;
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assert(fd >= 0);
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assert(st);
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if ((!uid_is_valid(uid) || st->st_uid == uid) &&
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(!gid_is_valid(gid) || st->st_gid == gid))
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return 0;
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/* We change ownership through the /proc/self/fd/%i path, so that we have a stable reference that works with
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* O_PATH. (Note: fchown() and fchmod() do not work with O_PATH, the kernel refuses that. */
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xsprintf(procfs_path, "/proc/self/fd/%i", fd);
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/* Drop any ACL if there is one */
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FOREACH_STRING(n, "system.posix_acl_access", "system.posix_acl_default")
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if (removexattr(procfs_path, n) < 0)
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if (!IN_SET(errno, ENODATA, EOPNOTSUPP, ENOSYS, ENOTTY))
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return -errno;
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if (chown(procfs_path, uid, gid) < 0)
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return -errno;
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/* The linux kernel alters the mode in some cases of chown(), as well when we change ACLs. Let's undo this. We
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* do this only for non-symlinks however. That's because for symlinks the access mode is ignored anyway and
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* because on some kernels/file systems trying to change the access mode will succeed but has no effect while
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* on others it actively fails. */
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if (!S_ISLNK(st->st_mode))
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if (chmod(procfs_path, st->st_mode & 07777) < 0)
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return -errno;
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return 1;
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}
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static int chown_recursive_internal(int fd, const struct stat *st, uid_t uid, gid_t gid) {
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_cleanup_closedir_ DIR *d = NULL;
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bool changed = false;
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struct dirent *de;
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int r;
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assert(fd >= 0);
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assert(st);
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d = fdopendir(fd);
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if (!d) {
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safe_close(fd);
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return -errno;
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}
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FOREACH_DIRENT_ALL(de, d, return -errno) {
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_cleanup_close_ int path_fd = -1;
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struct stat fst;
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if (dot_or_dot_dot(de->d_name))
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continue;
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/* Let's pin the child inode we want to fix now with an O_PATH fd, so that it cannot be swapped out
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* while we manipulate it. */
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path_fd = openat(dirfd(d), de->d_name, O_PATH|O_CLOEXEC|O_NOFOLLOW);
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if (path_fd < 0)
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return -errno;
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if (fstat(path_fd, &fst) < 0)
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return -errno;
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if (S_ISDIR(fst.st_mode)) {
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int subdir_fd;
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/* Convert it to a "real" (i.e. non-O_PATH) fd now */
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subdir_fd = fd_reopen(path_fd, O_RDONLY|O_CLOEXEC|O_NOATIME);
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if (subdir_fd < 0)
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return subdir_fd;
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r = chown_recursive_internal(subdir_fd, &fst, uid, gid); /* takes possession of subdir_fd even on failure */
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if (r < 0)
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return r;
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if (r > 0)
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changed = true;
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} else {
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r = chown_one(path_fd, &fst, uid, gid);
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if (r < 0)
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return r;
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if (r > 0)
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changed = true;
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}
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}
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r = chown_one(dirfd(d), st, uid, gid);
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if (r < 0)
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return r;
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return r > 0 || changed;
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}
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int path_chown_recursive(const char *path, uid_t uid, gid_t gid) {
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_cleanup_close_ int fd = -1;
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struct stat st;
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fd = open(path, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
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if (fd < 0)
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return -errno;
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if (!uid_is_valid(uid) && !gid_is_valid(gid))
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return 0; /* nothing to do */
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if (fstat(fd, &st) < 0)
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return -errno;
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/* Let's take a shortcut: if the top-level directory is properly owned, we don't descend into the whole tree,
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* under the assumption that all is OK anyway. */
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if ((!uid_is_valid(uid) || st.st_uid == uid) &&
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(!gid_is_valid(gid) || st.st_gid == gid))
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return 0;
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return chown_recursive_internal(TAKE_FD(fd), &st, uid, gid); /* we donate the fd to the call, regardless if it succeeded or failed */
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}
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