dilim/systemd
1
0
Fork 0
mirror of https://github.com/systemd/systemd.git synced 2026-08-09 09:32:04 +00:00
Code Issues Packages Projects Releases Wiki Activity

machine-id-setup: follow symlink target on --commit

Browse Source 
Resolve /etc/machine-id before checking the mount state and before
writing back, so symlinked targets are committed correctly.

Fixes: #43104
Follow-up for: efabf4e044
This commit is contained in:
dongshengyuan
2026-07-22 19:55:32 +08:00
committed by Yu Watanabe
parent 9d217e051b
commit aa776aefba
2 changed files with 73 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

71
src/shared/machine-id-setup.c
View File

@@ -318,17 +318,37 @@ int machine_id_commit(const char *root) {
* in a mount namespace, a new file is created at the right place. Afterwards the mount is also removed in the
* original mount namespace, thus revealing the file that was just created. */
_cleanup_close_ int etc_fd = -EBADF;
_cleanup_free_ char *etc = NULL;
r = chase("/etc/", root, CHASE_PREFIX_ROOT|CHASE_MUST_BE_DIRECTORY, &etc, &etc_fd);
_cleanup_close_ int etc_machine_id_fd = -EBADF;
_cleanup_free_ char *etc_machine_id = NULL;
r = chase("/etc/machine-id", root, CHASE_PREFIX_ROOT|CHASE_MUST_BE_REGULAR,
&etc_machine_id, &etc_machine_id_fd);
if (r == -ENOENT) {
_cleanup_close_ int etc_fd = -EBADF;
_cleanup_free_ char *etc = NULL, *target = NULL;
r = chase("/etc/", root, CHASE_PREFIX_ROOT|CHASE_MUST_BE_DIRECTORY, &etc, &etc_fd);
if (r < 0)
return log_error_errno(r, "Failed to open %s: %m", "/etc/");
etc_machine_id = path_join(etc, "machine-id");
if (!etc_machine_id)
return log_oom();
r = readlinkat_malloc(etc_fd, "machine-id", &target);
if (r == -ENOENT) {
log_debug_errno(r, "%s does not exist. Nothing to do.", etc_machine_id);
return 0;
}
if (r < 0)
return log_error_errno(r, "Failed to read symlink target of %s: %m", etc_machine_id);
log_debug("%s is a dangling symlink to %s. Nothing to do.", etc_machine_id, target);
return 0;
}
if (r < 0)
return log_error_errno(r, "Failed to open %s: %m", "/etc/");
return log_error_errno(r, "Failed to open %s: %m", "/etc/machine-id");
_cleanup_free_ char *etc_machine_id = path_join(etc, "machine-id");
if (!etc_machine_id)
return log_oom();
r = is_mount_point_at(etc_fd, "machine-id", /* flags= */ 0);
r = is_mount_point_at(etc_machine_id_fd, /* path= */ NULL, /* flags= */ 0);
if (r < 0)
return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id);
if (r == 0) {
@@ -338,11 +358,12 @@ int machine_id_commit(const char *root) {
/* Read existing machine-id */
_cleanup_close_ int fd = xopenat_full(etc_fd, "machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, XO_REGULAR, MODE_INVALID);
_cleanup_close_ int fd = xopenat_full(etc_machine_id_fd, /* path= */ NULL,
O_RDONLY|O_CLOEXEC|O_NOCTTY, XO_REGULAR, MODE_INVALID);
if (fd < 0)
return log_error_errno(fd, "Cannot open %s: %m", etc_machine_id);
etc_fd = safe_close(etc_fd);
etc_machine_id_fd = safe_close(etc_machine_id_fd);
r = fd_is_temporary_fs(fd);
if (r < 0)
@@ -366,22 +387,34 @@ int machine_id_commit(const char *root) {
if (r < 0)
return log_error_errno(r, "Failed to set up new mount namespace: %m");
/* Open /etc/ again after we transitioned into our own private mount namespace */
_cleanup_close_ int etc_fd_again = -EBADF;
r = chase("/etc/", root, CHASE_PREFIX_ROOT|CHASE_MUST_BE_DIRECTORY, /* ret_path= */ NULL, &etc_fd_again);
if (r < 0)
return log_error_errno(r, "Failed to open %s: %m", "/etc/");
_cleanup_free_ char *etc_machine_id_filename = NULL;
_cleanup_close_ int etc_machine_id_dir_fd =
chase_and_open_parent("/etc/machine-id", root, CHASE_PREFIX_ROOT, &etc_machine_id_filename);
if (etc_machine_id_dir_fd < 0)
return log_error_errno(etc_machine_id_dir_fd,
"Failed to open parent directory of %s: %m",
etc_machine_id);
r = umountat_detach_verbose(LOG_ERR, etc_fd_again, "machine-id");
r = inode_same_at(fd, /* filea= */ NULL,
etc_machine_id_dir_fd, etc_machine_id_filename, AT_EMPTY_PATH);
if (r < 0)
return log_error_errno(r, "Failed to verify %s before unmounting: %m", etc_machine_id);
if (r == 0)
return log_error_errno(SYNTHETIC_ERRNO(ESTALE),
"%s changed while preparing to commit.",
etc_machine_id);
r = umountat_detach_verbose(LOG_ERR, etc_machine_id_dir_fd, etc_machine_id_filename);
if (r < 0)
return r;
/* Update a persistent version of etc_machine_id */
r = id128_write_at(etc_fd_again, "machine-id", ID128_FORMAT_PLAIN | ID128_SYNC_ON_WRITE, id);
r = id128_write_at(etc_machine_id_dir_fd, etc_machine_id_filename,
ID128_FORMAT_PLAIN | ID128_SYNC_ON_WRITE, id);
if (r < 0)
return log_error_errno(r, "Cannot write %s. This is mandatory to get a persistent machine ID: %m", etc_machine_id);
etc_fd_again = safe_close(etc_fd_again);
etc_machine_id_dir_fd = safe_close(etc_machine_id_dir_fd);
/* Return to initial namespace and proceed a lazy tmpfs unmount */
r = namespace_enter(/* pidns_fd= */ -EBADF,

21
test/units/TEST-74-AUX-UTILS.machine-id-setup.sh
View File

@@ -69,6 +69,27 @@ testcase_transient() {
diff "$root/etc/machine-id" "$root/run/machine-id"
}
testcase_transient_symlink() {
local root transient_id committed_id
root="$(mktemp -d)"
trap "root_cleanup $root" RETURN
root_mock "$root"
mkdir -p "$root/persist/etc"
echo abc >>"$root/persist/etc/machine-id"
ln -s /persist/etc/machine-id "$root/etc/machine-id"
mount -o remount,ro "$root"
mount -t tmpfs tmpfs "$root/run"
transient_id="$(systemd-machine-id-setup --print --root "$root")"
mountpoint "$root/persist/etc/machine-id"
mount -o remount,rw "$root"
committed_id="$(systemd-machine-id-setup --print --commit --root "$root")"
[[ "$transient_id" == "$committed_id" ]]
(! mountpoint "$root/persist/etc/machine-id")
diff "$root/persist/etc/machine-id" "$root/run/machine-id"
}
# Check if we correctly processed the invalid machine ID we set up in the respective
# test.sh file
systemctl --state=failed --no-legend --no-pager | tee /failed