#include <sys/socket.h>

#include <sys/poll.h>

#include <sys/types.h>

#include <sys/timerfd.h>

#include <assert.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <fcntl.h>

#include <stddef.h>

#include "systemd/sd-daemon.h"

#include "systemd/sd-shutdown.h"

#include "log.h"

#include "macro.h"

#include "util.h"

#include "utmp-wtmp.h"

#include "mkdir.h"

#include "fileio.h"

union shutdown_buffer {

struct sd_shutdown_command command;

char space[offsetof(struct sd_shutdown_command, wall_message) + LINE_MAX];

};

static int read_packet(int fd, union shutdown_buffer *_b) {

struct ucred *ucred;

ssize_t n;

union shutdown_buffer b; /* We maintain our own copy here, in

struct iovec iovec = {

.iov_base = &b,

.iov_len = sizeof(b) - 1,

};

union {

struct cmsghdr cmsghdr;

uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];

} control = {};

struct msghdr msghdr = {

.msg_iov = &iovec,

.msg_iovlen = 1,

.msg_control = &control,

.msg_controllen = sizeof(control),

};

assert(fd >= 0);

assert(_b);

n = recvmsg(fd, &msghdr, MSG_DONTWAIT);

if (n <= 0) {

if (n == 0) {

log_error("Short read");

return -EIO;

}

if (errno == EAGAIN || errno == EINTR)

return 0;

log_error("recvmsg(): %m");

return -errno;

}

if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||

control.cmsghdr.cmsg_level != SOL_SOCKET ||

control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||

control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {

log_warning("Received message without credentials. Ignoring.");

return 0;

}

ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);

if (ucred->uid != 0) {

log_warning("Got request from unprivileged user. Ignoring.");

return 0;

}

if ((size_t) n < offsetof(struct sd_shutdown_command, wall_message)) {

log_warning("Message has invalid size. Ignoring.");

return 0;

}

if (b.command.mode != SD_SHUTDOWN_NONE &&

b.command.mode != SD_SHUTDOWN_REBOOT &&

b.command.mode != SD_SHUTDOWN_POWEROFF &&

b.command.mode != SD_SHUTDOWN_HALT &&

b.command.mode != SD_SHUTDOWN_KEXEC) {

log_warning("Message has invalid mode. Ignoring.");

return 0;

}

b.space[n] = 0;

*_b = b;

return 1;

}

static void warn_wall(usec_t n, struct sd_shutdown_command *c) {

char date[FORMAT_TIMESTAMP_MAX];

const char *prefix;

_cleanup_free_ char *l = NULL;

assert(c);

assert(c->warn_wall);

if (n >= c->usec)

return;

if (c->mode == SD_SHUTDOWN_HALT)

prefix = "The system is going down for system halt at ";

else if (c->mode == SD_SHUTDOWN_POWEROFF)

prefix = "The system is going down for power-off at ";

else if (c->mode == SD_SHUTDOWN_REBOOT)

prefix = "The system is going down for reboot at ";

else if (c->mode == SD_SHUTDOWN_KEXEC)

prefix = "The system is going down for kexec reboot at ";

else if (c->mode == SD_SHUTDOWN_NONE)

prefix = "The system shutdown has been cancelled at ";

else

assert_not_reached("Unknown mode!");

if (asprintf(&l, "%s%s%s%s!", c->wall_message, c->wall_message[0] ? "\n" : "",

prefix, format_timestamp(date, sizeof(date), c->usec)) >= 0)

utmp_wall(l, NULL, NULL);

else

log_error("Failed to allocate wall message");

}

_const_ static usec_t when_wall(usec_t n, usec_t elapse) {

static const struct {

usec_t delay;

usec_t interval;

} table[] = {

{ 0, USEC_PER_MINUTE },

{ 10 * USEC_PER_MINUTE, 15 * USEC_PER_MINUTE },

{ USEC_PER_HOUR, 30 * USEC_PER_MINUTE },

{ 3 * USEC_PER_HOUR, USEC_PER_HOUR },

};

usec_t left, sub;

unsigned i = ELEMENTSOF(table) - 1;

/* If the time is already passed, then don't announce */

if (n >= elapse)

return 0;

left = elapse - n;

while (left < table[i].delay)

i--;

sub = (left / table[i].interval) * table[i].interval;

assert(sub < elapse);

return elapse - sub;

}

static usec_t when_nologin(usec_t elapse) {

return elapse > 5*USEC_PER_MINUTE ? elapse - 5*USEC_PER_MINUTE : 1;

}

static const char *mode_to_string(enum sd_shutdown_mode m) {

switch (m) {

case SD_SHUTDOWN_REBOOT:

return "reboot";

case SD_SHUTDOWN_POWEROFF:

return "poweroff";

case SD_SHUTDOWN_HALT:

return "halt";

case SD_SHUTDOWN_KEXEC:

return "kexec";

default:

return NULL;

}

}

static int update_schedule_file(struct sd_shutdown_command *c) {

int r;

_cleanup_fclose_ FILE *f = NULL;

_cleanup_free_ char *t = NULL, *temp_path = NULL;

assert(c);

r = mkdir_safe_label("/run/systemd/shutdown", 0755, 0, 0);

if (r < 0) {

log_error_errno(-r, "Failed to create shutdown subdirectory: %m");

return r;

}

t = cescape(c->wall_message);

if (!t)

return log_oom();

r = fopen_temporary("/run/systemd/shutdown/scheduled", &f, &temp_path);

if (r < 0) {

log_error_errno(-r, "Failed to save information about scheduled shutdowns: %m");

return r;

}

fchmod(fileno(f), 0644);

fprintf(f,

"USEC="USEC_FMT"\n"

"WARN_WALL=%i\n"

"MODE=%s\n",

c->usec,

c->warn_wall,

mode_to_string(c->mode));

if (c->dry_run)

fputs("DRY_RUN=1\n", f);

if (!isempty(t))

fprintf(f, "WALL_MESSAGE=%s\n", t);

fflush(f);

if (ferror(f) || rename(temp_path, "/run/systemd/shutdown/scheduled") < 0) {

log_error("Failed to write information about scheduled shutdowns: %m");

r = -errno;

unlink(temp_path);

unlink("/run/systemd/shutdown/scheduled");

}

return r;

}

static bool scheduled(struct sd_shutdown_command *c) {

return c->usec > 0 && c->mode != SD_SHUTDOWN_NONE;

}

int main(int argc, char *argv[]) {

enum {

FD_SOCKET,

FD_WALL_TIMER,

FD_NOLOGIN_TIMER,

FD_SHUTDOWN_TIMER,

_FD_MAX

};

int r = EXIT_FAILURE, n_fds;

union shutdown_buffer b = {};

struct pollfd pollfd[_FD_MAX] = {};

bool exec_shutdown = false, unlink_nologin = false;

unsigned i;

if (getppid() != 1) {

log_error("This program should be invoked by init only.");

return EXIT_FAILURE;

}

if (argc > 1) {

log_error("This program does not take arguments.");

return EXIT_FAILURE;

}

log_set_target(LOG_TARGET_AUTO);

log_parse_environment();

log_open();

umask(0022);

n_fds = sd_listen_fds(true);

if (n_fds < 0) {

log_error_errno(-r, "Failed to read listening file descriptors from environment: %m");

return EXIT_FAILURE;

}

if (n_fds != 1) {

log_error("Need exactly one file descriptor.");

return EXIT_FAILURE;

}

pollfd[FD_SOCKET].fd = SD_LISTEN_FDS_START;

pollfd[FD_SOCKET].events = POLLIN;

for (i = FD_WALL_TIMER; i < _FD_MAX; i++) {

pollfd[i].events = POLLIN;

pollfd[i].fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC);

if (pollfd[i].fd < 0) {

log_error("timerfd_create(): %m");

goto finish;

}

}

log_debug("systemd-shutdownd running as pid "PID_FMT, getpid());

sd_notify(false,

"READY=1\n"

"STATUS=Processing requests...");

for (;;) {

int k;

usec_t n;

k = poll(pollfd, _FD_MAX, scheduled(&b.command) ? -1 : 0);

if (k < 0) {

if (errno == EAGAIN || errno == EINTR)

continue;

log_error("poll(): %m");

goto finish;

}

/* Exit on idle */

if (k == 0)

break;

n = now(CLOCK_REALTIME);

if (pollfd[FD_SOCKET].revents) {

k = read_packet(pollfd[FD_SOCKET].fd, &b);

if (k < 0)

goto finish;

else if (k > 0) {

struct itimerspec its;

char date[FORMAT_TIMESTAMP_MAX];

if (!scheduled(&b.command)) {

log_info("Shutdown canceled.");

if (b.command.warn_wall)

warn_wall(0, &b.command);

break;

}

zero(its);

if (b.command.warn_wall) {

/* Send wall messages every so often */

timespec_store(&its.it_value, when_wall(n, b.command.usec));

/* Warn immediately if less than 15 minutes are left */

if (n < b.command.usec &&

n + 15*USEC_PER_MINUTE >= b.command.usec)

warn_wall(n, &b.command);

}

if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {

log_error("timerfd_settime(): %m");

goto finish;

}

/* Disallow logins 5 minutes prior to shutdown */

zero(its);

timespec_store(&its.it_value, when_nologin(b.command.usec));

if (timerfd_settime(pollfd[FD_NOLOGIN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {

log_error("timerfd_settime(): %m");

goto finish;

}

/* Shutdown after the specified time is reached */

zero(its);

timespec_store(&its.it_value, b.command.usec);

if (timerfd_settime(pollfd[FD_SHUTDOWN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {

log_error("timerfd_settime(): %m");

goto finish;

}

update_schedule_file(&b.command);

sd_notifyf(false,

"STATUS=Shutting down at %s (%s)...",

format_timestamp(date, sizeof(date), b.command.usec),

mode_to_string(b.command.mode));

log_info("Shutting down at %s (%s)...", date, mode_to_string(b.command.mode));

}

}

if (pollfd[FD_WALL_TIMER].revents) {

struct itimerspec its = {};

warn_wall(n, &b.command);

flush_fd(pollfd[FD_WALL_TIMER].fd);

/* Restart timer */

timespec_store(&its.it_value, when_wall(n, b.command.usec));

if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {

log_error("timerfd_settime(): %m");

goto finish;

}

}

if (pollfd[FD_NOLOGIN_TIMER].revents) {

int e;

log_info("Creating /run/nologin, blocking further logins...");

e = write_string_file_atomic("/run/nologin", "System is going down.");

if (e < 0)

log_error_errno(-e, "Failed to create /run/nologin: %m");

else

unlink_nologin = true;

flush_fd(pollfd[FD_NOLOGIN_TIMER].fd);

}

if (pollfd[FD_SHUTDOWN_TIMER].revents) {

exec_shutdown = true;

goto finish;

}

}

r = EXIT_SUCCESS;

log_debug("systemd-shutdownd stopped as pid "PID_FMT, getpid());

finish:

for (i = 0; i < _FD_MAX; i++)

safe_close(pollfd[i].fd);

if (unlink_nologin)

unlink("/run/nologin");

unlink("/run/systemd/shutdown/scheduled");

if (exec_shutdown && !b.command.dry_run) {

char sw[3];

sw[0] = '-';

sw[1] = b.command.mode;

sw[2] = 0;

execl(SYSTEMCTL_BINARY_PATH,

"shutdown",

sw,

"now",

(b.command.warn_wall && b.command.wall_message[0]) ? b.command.wall_message :

(b.command.warn_wall ? NULL : "--no-wall"),

NULL);

log_error("Failed to execute /sbin/shutdown: %m");

}

sd_notify(false,

"STOPPING=\n"

"STATUS=Exiting...");

return r;

}