src/shutdownd.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/socket.h>
  23 #include <sys/poll.h>
  24 #include <sys/types.h>
  25 #include <sys/timerfd.h>
  26 #include <assert.h>
  27 #include <string.h>
  28 #include <errno.h>
  29 #include <unistd.h>
  30 #include <fcntl.h>
  31
  32 #include "shutdownd.h"
  33 #include "log.h"
  34 #include "macro.h"
  35 #include "util.h"
  36 #include "sd-daemon.h"
  37 #include "utmp-wtmp.h"
  38
  39 static int read_packet(int fd, struct shutdownd_command *_c) {
  40         struct msghdr msghdr;
  41         struct iovec iovec;
  42         struct ucred *ucred;
  43         union {
  44                 struct cmsghdr cmsghdr;
  45                 uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
  46         } control;
  47         struct shutdownd_command c;
  48         ssize_t n;
  49
  50         assert(fd >= 0);
  51         assert(_c);
  52
  53         zero(iovec);
  54         iovec.iov_base = &c;
  55         iovec.iov_len = sizeof(c);
  56
  57         zero(control);
  58         zero(msghdr);
  59         msghdr.msg_iov = &iovec;
  60         msghdr.msg_iovlen = 1;
  61         msghdr.msg_control = &control;
  62         msghdr.msg_controllen = sizeof(control);
  63
  64         if ((n = recvmsg(fd, &msghdr, MSG_DONTWAIT)) <= 0) {
  65                 if (n >= 0) {
  66                         log_error("Short read");
  67                         return -EIO;
  68                 }
  69
  70                 if (errno == EAGAIN || errno == EINTR)
  71                         return 0;
  72
  73                 log_error("recvmsg(): %m");
  74                 return -errno;
  75         }
  76
  77         if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
  78             control.cmsghdr.cmsg_level != SOL_SOCKET ||
  79             control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
  80             control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
  81                 log_warning("Received message without credentials. Ignoring.");
  82                 return 0;
  83         }
  84
  85         ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
  86         if (ucred->uid != 0) {
  87                 log_warning("Got request from unprivileged user. Ignoring.");
  88                 return 0;
  89         }
  90
  91         if (n != sizeof(c)) {
  92                 log_warning("Message has invalid size. Ignoring");
  93                 return 0;
  94         }
  95
  96         char_array_0(c.wall_message);
  97
  98         *_c = c;
  99         return 1;
 100 }
 101
 102 static void warn_wall(usec_t n, struct shutdownd_command *c) {
 103         char date[FORMAT_TIMESTAMP_MAX];
 104         const char *prefix;
 105         char *l = NULL;
 106
 107         assert(c);
 108         assert(c->warn_wall);
 109
 110         if (n >= c->elapse)
 111                 return;
 112
 113         if (c->mode == 'H')
 114                 prefix = "The system is going down for system halt at ";
 115         else if (c->mode == 'P')
 116                 prefix = "The system is going down for power-off at ";
 117         else if (c->mode == 'r')
 118                 prefix = "The system is going down for reboot at ";
 119         else
 120                 assert_not_reached("Unknown mode!");
 121
 122         if (asprintf(&l, "%s%s%s%s!", c->wall_message, c->wall_message[0] ? "\n" : "",
 123                      prefix, format_timestamp(date, sizeof(date), c->elapse)) < 0)
 124                 log_error("Failed to allocate wall message");
 125         else {
 126                 utmp_wall(l, NULL);
 127                 free(l);
 128         }
 129 }
 130
 131 static usec_t when_wall(usec_t n, usec_t elapse) {
 132
 133         static const struct {
 134                 usec_t delay;
 135                 usec_t interval;
 136         } table[] = {
 137                 { 10 * USEC_PER_MINUTE, USEC_PER_MINUTE      },
 138                 { USEC_PER_HOUR,        15 * USEC_PER_MINUTE },
 139                 { 3 * USEC_PER_HOUR,    30 * USEC_PER_MINUTE }
 140         };
 141
 142         usec_t left, sub;
 143         unsigned i;
 144
 145         /* If the time is already passed, then don't announce */
 146         if (n >= elapse)
 147                 return 0;
 148
 149         left = elapse - n;
 150         for (i = 0; i < ELEMENTSOF(table); i++)
 151                 if (n + table[i].delay >= elapse) {
 152                         sub = ((left / table[i].interval) * table[i].interval);
 153                         break;
 154                 }
 155
 156         if (i >= ELEMENTSOF(table))
 157                 sub = ((left / USEC_PER_HOUR) * USEC_PER_HOUR);
 158
 159         return elapse > sub ? elapse - sub : 1;
 160 }
 161
 162 static usec_t when_nologin(usec_t elapse) {
 163         return elapse > 5*USEC_PER_MINUTE ? elapse - 5*USEC_PER_MINUTE : 1;
 164 }
 165
 166 int main(int argc, char *argv[]) {
 167         enum {
 168                 FD_SOCKET,
 169                 FD_WALL_TIMER,
 170                 FD_NOLOGIN_TIMER,
 171                 FD_SHUTDOWN_TIMER,
 172                 _FD_MAX
 173         };
 174
 175         int r = EXIT_FAILURE, n_fds;
 176         struct shutdownd_command c;
 177         struct pollfd pollfd[_FD_MAX];
 178         bool exec_shutdown = false, unlink_nologin = false, failed = false;
 179         unsigned i;
 180
 181         if (getppid() != 1) {
 182                 log_error("This program should be invoked by init only.");
 183                 return EXIT_FAILURE;
 184         }
 185
 186         if (argc > 1) {
 187                 log_error("This program does not take arguments.");
 188                 return EXIT_FAILURE;
 189         }
 190
 191         log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
 192         log_parse_environment();
 193         log_open();
 194
 195         umask(0022);
 196
 197         if ((n_fds = sd_listen_fds(true)) < 0) {
 198                 log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
 199                 return EXIT_FAILURE;
 200         }
 201
 202         if (n_fds != 1) {
 203                 log_error("Need exactly one file descriptor.");
 204                 return EXIT_FAILURE;
 205         }
 206
 207         zero(c);
 208         zero(pollfd);
 209
 210         pollfd[FD_SOCKET].fd = SD_LISTEN_FDS_START;
 211         pollfd[FD_SOCKET].events = POLLIN;
 212
 213         for (i = 0; i < _FD_MAX; i++) {
 214
 215                 if (i == FD_SOCKET)
 216                         continue;
 217
 218                 pollfd[i].events = POLLIN;
 219
 220                 if ((pollfd[i].fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC)) < 0) {
 221                         log_error("timerfd_create(): %m");
 222                         failed = true;
 223                 }
 224         }
 225
 226         if (failed)
 227                 goto finish;
 228
 229         log_debug("systemd-shutdownd running as pid %lu", (unsigned long) getpid());
 230
 231         sd_notify(false,
 232                   "READY=1\n"
 233                   "STATUS=Processing requests...");
 234
 235         do {
 236                 int k;
 237                 usec_t n;
 238
 239                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 240
 241                         if (errno == EAGAIN || errno == EINTR)
 242                                 continue;
 243
 244                         log_error("poll(): %m");
 245                         goto finish;
 246                 }
 247
 248                 n = now(CLOCK_REALTIME);
 249
 250                 if (pollfd[FD_SOCKET].revents) {
 251
 252                         if ((k = read_packet(pollfd[FD_SOCKET].fd, &c)) < 0)
 253                                 goto finish;
 254                         else if (k > 0 && c.elapse > 0) {
 255                                 struct itimerspec its;
 256                                 char date[FORMAT_TIMESTAMP_MAX];
 257
 258                                 if (c.warn_wall) {
 259                                         /* Send wall messages every so often */
 260                                         zero(its);
 261                                         timespec_store(&its.it_value, when_wall(n, c.elapse));
 262                                         if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 263                                                 log_error("timerfd_settime(): %m");
 264                                                 goto finish;
 265                                         }
 266
 267                                         /* Warn immediately if less than 15 minutes are left */
 268                                         if (n < c.elapse &&
 269                                             n + 15*USEC_PER_MINUTE >= c.elapse)
 270                                                 warn_wall(n, &c);
 271                                 }
 272
 273                                 /* Disallow logins 5 minutes prior to shutdown */
 274                                 zero(its);
 275                                 timespec_store(&its.it_value, when_nologin(c.elapse));
 276                                 if (timerfd_settime(pollfd[FD_NOLOGIN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 277                                         log_error("timerfd_settime(): %m");
 278                                         goto finish;
 279                                 }
 280
 281                                 /* Shutdown after the specified time is reached */
 282                                 zero(its);
 283                                 timespec_store(&its.it_value, c.elapse);
 284                                 if (timerfd_settime(pollfd[FD_SHUTDOWN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 285                                         log_error("timerfd_settime(): %m");
 286                                         goto finish;
 287                                 }
 288
 289                                 sd_notifyf(false,
 290                                            "STATUS=Shutting down at %s...",
 291                                            format_timestamp(date, sizeof(date), c.elapse));
 292                         }
 293                 }
 294
 295                 if (pollfd[FD_WALL_TIMER].revents) {
 296                         struct itimerspec its;
 297
 298                         warn_wall(n, &c);
 299                         flush_fd(pollfd[FD_WALL_TIMER].fd);
 300
 301                         /* Restart timer */
 302                         zero(its);
 303                         timespec_store(&its.it_value, when_wall(n, c.elapse));
 304                         if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 305                                 log_error("timerfd_settime(): %m");
 306                                 goto finish;
 307                         }
 308                 }
 309
 310                 if (pollfd[FD_NOLOGIN_TIMER].revents) {
 311                         int e;
 312
 313                         log_info("Creating /run/nologin, blocking further logins...");
 314
 315                         if ((e = write_one_line_file_atomic("/run/nologin", "System is going down.")) < 0)
 316                                 log_error("Failed to create /run/nologin: %s", strerror(-e));
 317                         else
 318                                 unlink_nologin = true;
 319
 320                         flush_fd(pollfd[FD_NOLOGIN_TIMER].fd);
 321                 }
 322
 323                 if (pollfd[FD_SHUTDOWN_TIMER].revents) {
 324                         exec_shutdown = true;
 325                         goto finish;
 326                 }
 327
 328         } while (c.elapse > 0);
 329
 330         r = EXIT_SUCCESS;
 331
 332         log_debug("systemd-shutdownd stopped as pid %lu", (unsigned long) getpid());
 333
 334 finish:
 335
 336         for (i = 0; i < _FD_MAX; i++)
 337                 if (pollfd[i].fd >= 0)
 338                         close_nointr_nofail(pollfd[i].fd);
 339
 340         if (unlink_nologin)
 341                 unlink("/run/nologin");
 342
 343         if (exec_shutdown && !c.dry_run) {
 344                 char sw[3];
 345
 346                 sw[0] = '-';
 347                 sw[1] = c.mode;
 348                 sw[2] = 0;
 349
 350                 execl(SYSTEMCTL_BINARY_PATH,
 351                       "shutdown",
 352                       sw,
 353                       "now",
 354                       (c.warn_wall && c.wall_message[0]) ? c.wall_message :
 355                       (c.warn_wall ? NULL : "--no-wall"),
 356                       NULL);
 357
 358                 log_error("Failed to execute /sbin/shutdown: %m");
 359         }
 360
 361         sd_notify(false,
 362                   "STATUS=Exiting...");
 363
 364         return r;
 365 }