#include <unistd.h>

#include <stdio.h>

#include <errno.h>

#include <string.h>

#include <fcntl.h>

#include <sys/mount.h>

#include "systemd/sd-id128.h"

#include "machine-id-setup.h"

#include "macro.h"

#include "util.h"

#include "mkdir.h"

#include "log.h"

#include "virt.h"

#include "fileio.h"

#include "path-util.h"

#include "process-util.h"

static int shorten_uuid(char destination[34], const char source[36]) {

unsigned i, j;

assert(destination);

assert(source);

/* Converts a UUID into a machine ID, by lowercasing it and

for (i = 0, j = 0; i < 36 && j < 32; i++) {

int t;

t = unhexchar(source[i]);

if (t < 0)

continue;

destination[j++] = hexchar(t);

}

if (i != 36 || j != 32)

return -EINVAL;

destination[32] = '\n';

destination[33] = 0;

return 0;

}

static int read_machine_id(int fd, char id[34]) {

char id_to_validate[34];

int r;

assert(fd >= 0);

assert(id);

/* Reads a machine ID from a file, validates it, and returns

r = loop_read_exact(fd, id_to_validate, 33, false);

if (r < 0)

return r;

if (id_to_validate[32] != '\n')

return -EINVAL;

id_to_validate[32] = 0;

if (!id128_is_valid(id_to_validate))

return -EINVAL;

memcpy(id, id_to_validate, 32);

id[32] = '\n';

id[33] = 0;

return 0;

}

static int write_machine_id(int fd, char id[34]) {

assert(fd >= 0);

assert(id);

if (lseek(fd, 0, SEEK_SET) < 0)

return -errno;

return loop_write(fd, id, 33, false);

}

static int generate_machine_id(char id[34], const char *root) {

int fd, r;

unsigned char *p;

sd_id128_t buf;

char *q;

const char *vm_id, *dbus_machine_id;

assert(id);

if (isempty(root))

dbus_machine_id = "/var/lib/dbus/machine-id";

else

dbus_machine_id = strjoina(root, "/var/lib/dbus/machine-id");

/* First, try reading the D-Bus machine id, unless it is a symlink */

fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);

if (fd >= 0) {

r = read_machine_id(fd, id);

safe_close(fd);

if (r >= 0) {

log_info("Initializing machine ID from D-Bus machine ID.");

return 0;

}

}

if (isempty(root)) {

/* If that didn't work, see if we are running in a container,

r = detect_container(NULL);

if (r > 0) {

_cleanup_free_ char *e = NULL;

r = getenv_for_pid(1, "container_uuid", &e);

if (r > 0) {

r = shorten_uuid(id, e);

if (r >= 0) {

log_info("Initializing machine ID from container UUID.");

return 0;

}

}

} else {

/* If we are not running in a container, see if we are

r = detect_vm(&vm_id);

if (r > 0 && streq(vm_id, "kvm")) {

char uuid[36];

fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);

if (fd >= 0) {

r = loop_read_exact(fd, uuid, 36, false);

safe_close(fd);

if (r >= 0) {

r = shorten_uuid(id, uuid);

if (r >= 0) {

log_info("Initializing machine ID from KVM UUID.");

return 0;

}

}

}

}

}

}

/* If that didn't work, generate a random machine id */

r = sd_id128_randomize(&buf);

if (r < 0)

return log_error_errno(r, "Failed to open /dev/urandom: %m");

for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) {

q[0] = hexchar(*p >> 4);

q[1] = hexchar(*p & 15);

}

id[32] = '\n';

id[33] = 0;

log_info("Initializing machine ID from random generator.");

return 0;

}

int machine_id_setup(const char *root) {

const char *etc_machine_id, *run_machine_id;

_cleanup_close_ int fd = -1;

bool writable = true;

char id[34]; /* 32 + \n + \0 */

int r;

if (isempty(root)) {

etc_machine_id = "/etc/machine-id";

run_machine_id = "/run/machine-id";

} else {

char *x;

x = strjoina(root, "/etc/machine-id");

etc_machine_id = path_kill_slashes(x);

x = strjoina(root, "/run/machine-id");

run_machine_id = path_kill_slashes(x);

}

RUN_WITH_UMASK(0000) {

/* We create this 0444, to indicate that this isn't really

mkdir_parents(etc_machine_id, 0755);

fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);

if (fd < 0) {

int old_errno = errno;

fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);

if (fd < 0) {

if (old_errno == EROFS && errno == ENOENT)

log_error_errno(errno,

"System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"

"Booting up is supported only when:\n"

"1) /etc/machine-id exists and is populated.\n"

"2) /etc/machine-id exists and is empty.\n"

"3) /etc/machine-id is missing and /etc is writable.\n");

else

log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);

return -errno;

}

writable = false;

}

}

if (read_machine_id(fd, id) >= 0)

return 0;

/* Hmm, so, the id currently stored is not useful, then let's

r = generate_machine_id(id, root);

if (r < 0)

return r;

if (writable)

if (write_machine_id(fd, id) >= 0)

return 0;

fd = safe_close(fd);

/* Hmm, we couldn't write it? So let's write it to

RUN_WITH_UMASK(0022) {

r = write_string_file(run_machine_id, id, WRITE_STRING_FILE_CREATE);

}

if (r < 0) {

(void) unlink(run_machine_id);

return log_error_errno(r, "Cannot write %s: %m", run_machine_id);

}

/* And now, let's mount it over */

if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) {

(void) unlink_noerrno(run_machine_id);

return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);

}

log_info("Installed transient %s file.", etc_machine_id);

/* Mark the mount read-only */

if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)

log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);

return 0;

}

int machine_id_commit(const char *root) {

_cleanup_close_ int fd = -1, initial_mntns_fd = -1;

const char *etc_machine_id;

char id[34]; /* 32 + \n + \0 */

int r;

if (isempty(root))

etc_machine_id = "/etc/machine-id";

else {

char *x;

x = strjoina(root, "/etc/machine-id");

etc_machine_id = path_kill_slashes(x);

}

r = path_is_mount_point(etc_machine_id, 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) {

log_debug("%s is is not a mount point. Nothing to do.", etc_machine_id);

return 0;

}

/* Read existing machine-id */

fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);

if (fd < 0)

return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);

r = read_machine_id(fd, id);

if (r < 0)

return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id);

r = fd_is_temporary_fs(fd);

if (r < 0)

return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id);

if (r == 0) {

log_error("%s is not on a temporary file system.", etc_machine_id);

return -EROFS;

}

fd = safe_close(fd);

/* Store current mount namespace */

r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL, NULL);

if (r < 0)

return log_error_errno(r, "Can't fetch current mount namespace: %m");

/* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */

if (unshare(CLONE_NEWNS) < 0)

return log_error_errno(errno, "Failed to enter new namespace: %m");

if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0)

return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m");

if (umount(etc_machine_id) < 0)

return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id);

/* Update a persistent version of etc_machine_id */

fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);

if (fd < 0)

return log_error_errno(errno, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m", etc_machine_id);

r = write_machine_id(fd, id);

if (r < 0)

return log_error_errno(r, "Cannot write %s: %m", etc_machine_id);

fd = safe_close(fd);

/* Return to initial namespace and proceed a lazy tmpfs unmount */

r = namespace_enter(-1, initial_mntns_fd, -1, -1, -1);

if (r < 0)

return log_warning_errno(r, "Failed to switch back to initial mount namespace: %m.\nWe'll keep transient %s file until next reboot.", etc_machine_id);

if (umount2(etc_machine_id, MNT_DETACH) < 0)

return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id);

return 0;

}