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 #include <stddef.h>
  32
  33 #include <systemd/sd-daemon.h>
  34 #include <systemd/sd-shutdown.h>
  35
  36 #include "log.h"
  37 #include "macro.h"
  38 #include "util.h"
  39 #include "utmp-wtmp.h"
  40 #include "mkdir.h"
  41
  42 union shutdown_buffer {
  43         struct sd_shutdown_command command;
  44         char space[offsetof(struct sd_shutdown_command, wall_message) + LINE_MAX];
  45 };
  46
  47 static int read_packet(int fd, union shutdown_buffer *_b) {
  48         struct msghdr msghdr;
  49         struct iovec iovec;
  50         struct ucred *ucred;
  51         union {
  52                 struct cmsghdr cmsghdr;
  53                 uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
  54         } control;
  55         ssize_t n;
  56         union shutdown_buffer b; /* We maintain our own copy here, in order not to corrupt the last message */
  57
  58         assert(fd >= 0);
  59         assert(_b);
  60
  61         zero(iovec);
  62         iovec.iov_base = &b;
  63         iovec.iov_len = sizeof(b) - 1;
  64
  65         zero(control);
  66         zero(msghdr);
  67         msghdr.msg_iov = &iovec;
  68         msghdr.msg_iovlen = 1;
  69         msghdr.msg_control = &control;
  70         msghdr.msg_controllen = sizeof(control);
  71
  72         n = recvmsg(fd, &msghdr, MSG_DONTWAIT);
  73         if (n <= 0) {
  74                 if (n == 0) {
  75                         log_error("Short read");
  76                         return -EIO;
  77                 }
  78
  79                 if (errno == EAGAIN || errno == EINTR)
  80                         return 0;
  81
  82                 log_error("recvmsg(): %m");
  83                 return -errno;
  84         }
  85
  86         if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
  87             control.cmsghdr.cmsg_level != SOL_SOCKET ||
  88             control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
  89             control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
  90                 log_warning("Received message without credentials. Ignoring.");
  91                 return 0;
  92         }
  93
  94         ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
  95         if (ucred->uid != 0) {
  96                 log_warning("Got request from unprivileged user. Ignoring.");
  97                 return 0;
  98         }
  99
 100         if ((size_t) n < offsetof(struct sd_shutdown_command, wall_message)) {
 101                 log_warning("Message has invalid size. Ignoring.");
 102                 return 0;
 103         }
 104
 105         if (b.command.mode != SD_SHUTDOWN_NONE &&
 106             b.command.mode != SD_SHUTDOWN_REBOOT &&
 107             b.command.mode != SD_SHUTDOWN_POWEROFF &&
 108             b.command.mode != SD_SHUTDOWN_HALT &&
 109             b.command.mode != SD_SHUTDOWN_KEXEC) {
 110                 log_warning("Message has invalid mode. Ignoring.");
 111                 return 0;
 112         }
 113
 114         b.space[n] = 0;
 115
 116         *_b = b;
 117         return 1;
 118 }
 119
 120 static void warn_wall(usec_t n, struct sd_shutdown_command *c) {
 121         char date[FORMAT_TIMESTAMP_MAX];
 122         const char *prefix;
 123         char *l = NULL;
 124
 125         assert(c);
 126         assert(c->warn_wall);
 127
 128         if (n >= c->usec)
 129                 return;
 130
 131         if (c->mode == SD_SHUTDOWN_HALT)
 132                 prefix = "The system is going down for system halt at ";
 133         else if (c->mode == SD_SHUTDOWN_POWEROFF)
 134                 prefix = "The system is going down for power-off at ";
 135         else if (c->mode == SD_SHUTDOWN_REBOOT)
 136                 prefix = "The system is going down for reboot at ";
 137         else if (c->mode == SD_SHUTDOWN_KEXEC)
 138                 prefix = "The system is going down for kexec reboot at ";
 139         else
 140                 assert_not_reached("Unknown mode!");
 141
 142         if (asprintf(&l, "%s%s%s%s!", c->wall_message, c->wall_message[0] ? "\n" : "",
 143                      prefix, format_timestamp(date, sizeof(date), c->usec)) < 0)
 144                 log_error("Failed to allocate wall message");
 145         else {
 146                 utmp_wall(l, NULL);
 147                 free(l);
 148         }
 149 }
 150
 151 static usec_t when_wall(usec_t n, usec_t elapse) {
 152
 153         static const struct {
 154                 usec_t delay;
 155                 usec_t interval;
 156         } table[] = {
 157                 { 10 * USEC_PER_MINUTE, USEC_PER_MINUTE      },
 158                 { USEC_PER_HOUR,        15 * USEC_PER_MINUTE },
 159                 { 3 * USEC_PER_HOUR,    30 * USEC_PER_MINUTE }
 160         };
 161
 162         usec_t left, sub;
 163         unsigned i;
 164
 165         /* If the time is already passed, then don't announce */
 166         if (n >= elapse)
 167                 return 0;
 168
 169         left = elapse - n;
 170         for (i = 0; i < ELEMENTSOF(table); i++)
 171                 if (n + table[i].delay >= elapse) {
 172                         sub = ((left / table[i].interval) * table[i].interval);
 173                         break;
 174                 }
 175
 176         if (i >= ELEMENTSOF(table))
 177                 sub = ((left / USEC_PER_HOUR) * USEC_PER_HOUR);
 178
 179         return elapse > sub ? elapse - sub : 1;
 180 }
 181
 182 static usec_t when_nologin(usec_t elapse) {
 183         return elapse > 5*USEC_PER_MINUTE ? elapse - 5*USEC_PER_MINUTE : 1;
 184 }
 185
 186 static const char *mode_to_string(enum sd_shutdown_mode m) {
 187         switch (m) {
 188         case SD_SHUTDOWN_REBOOT:
 189                 return "reboot";
 190         case SD_SHUTDOWN_POWEROFF:
 191                 return "poweroff";
 192         case SD_SHUTDOWN_HALT:
 193                 return "halt";
 194         case SD_SHUTDOWN_KEXEC:
 195                 return "kexec";
 196         default:
 197                 return NULL;
 198         }
 199 }
 200
 201 static int update_schedule_file(struct sd_shutdown_command *c) {
 202         int r;
 203         FILE *f;
 204         char *temp_path, *t;
 205
 206         assert(c);
 207
 208         r = safe_mkdir("/run/systemd/shutdown", 0755, 0, 0);
 209         if (r < 0) {
 210                 log_error("Failed to create shutdown subdirectory: %s", strerror(-r));
 211                 return r;
 212         }
 213
 214         t = cescape(c->wall_message);
 215         if (!t) {
 216                 log_error("Out of memory");
 217                 return -ENOMEM;
 218         }
 219
 220         r = fopen_temporary("/run/systemd/shutdown/scheduled", &f, &temp_path);
 221         if (r < 0) {
 222                 log_error("Failed to save information about scheduled shutdowns: %s", strerror(-r));
 223                 free(t);
 224                 return r;
 225         }
 226
 227         fchmod(fileno(f), 0644);
 228
 229         fprintf(f,
 230                 "USEC=%llu\n"
 231                 "WARN_WALL=%i\n"
 232                 "MODE=%s\n",
 233                 (unsigned long long) c->usec,
 234                 c->warn_wall,
 235                 mode_to_string(c->mode));
 236
 237         if (c->dry_run)
 238                 fputs("DRY_RUN=1\n", f);
 239
 240         if (!isempty(t))
 241                 fprintf(f, "WALL_MESSAGE=%s\n", t);
 242
 243         free(t);
 244
 245         fflush(f);
 246
 247         if (ferror(f) || rename(temp_path, "/run/systemd/shutdown/scheduled") < 0) {
 248                 log_error("Failed to write information about scheduled shutdowns: %m");
 249                 r = -errno;
 250
 251                 unlink(temp_path);
 252                 unlink("/run/systemd/shutdown/scheduled");
 253         }
 254
 255         fclose(f);
 256         free(temp_path);
 257
 258         return r;
 259 }
 260
 261 static bool scheduled(struct sd_shutdown_command *c) {
 262         return c->usec > 0 && c->mode != SD_SHUTDOWN_NONE;
 263 }
 264
 265 int main(int argc, char *argv[]) {
 266         enum {
 267                 FD_SOCKET,
 268                 FD_WALL_TIMER,
 269                 FD_NOLOGIN_TIMER,
 270                 FD_SHUTDOWN_TIMER,
 271                 _FD_MAX
 272         };
 273
 274         int r = EXIT_FAILURE, n_fds;
 275         union shutdown_buffer b;
 276         struct pollfd pollfd[_FD_MAX];
 277         bool exec_shutdown = false, unlink_nologin = false;
 278         unsigned i;
 279
 280         if (getppid() != 1) {
 281                 log_error("This program should be invoked by init only.");
 282                 return EXIT_FAILURE;
 283         }
 284
 285         if (argc > 1) {
 286                 log_error("This program does not take arguments.");
 287                 return EXIT_FAILURE;
 288         }
 289
 290         log_set_target(LOG_TARGET_AUTO);
 291         log_parse_environment();
 292         log_open();
 293
 294         umask(0022);
 295
 296         n_fds = sd_listen_fds(true);
 297         if (n_fds < 0) {
 298                 log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
 299                 return EXIT_FAILURE;
 300         }
 301
 302         if (n_fds != 1) {
 303                 log_error("Need exactly one file descriptor.");
 304                 return EXIT_FAILURE;
 305         }
 306
 307         zero(b);
 308         zero(pollfd);
 309
 310         pollfd[FD_SOCKET].fd = SD_LISTEN_FDS_START;
 311         pollfd[FD_SOCKET].events = POLLIN;
 312
 313         for (i = FD_WALL_TIMER; i < _FD_MAX; i++) {
 314                 pollfd[i].events = POLLIN;
 315                 pollfd[i].fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC);
 316                 if (pollfd[i].fd < 0) {
 317                         log_error("timerfd_create(): %m");
 318                         goto finish;
 319                 }
 320         }
 321
 322         log_debug("systemd-shutdownd running as pid %lu", (unsigned long) getpid());
 323
 324         sd_notify(false,
 325                   "READY=1\n"
 326                   "STATUS=Processing requests...");
 327
 328         for (;;) {
 329                 int k;
 330                 usec_t n;
 331
 332                 k = poll(pollfd, _FD_MAX, scheduled(&b.command) ? -1 : 0);
 333                 if (k < 0) {
 334
 335                         if (errno == EAGAIN || errno == EINTR)
 336                                 continue;
 337
 338                         log_error("poll(): %m");
 339                         goto finish;
 340                 }
 341
 342                 /* Exit on idle */
 343                 if (k == 0)
 344                         break;
 345
 346                 n = now(CLOCK_REALTIME);
 347
 348                 if (pollfd[FD_SOCKET].revents) {
 349
 350                         k = read_packet(pollfd[FD_SOCKET].fd, &b);
 351                         if (k < 0)
 352                                 goto finish;
 353                         else if (k > 0) {
 354                                 struct itimerspec its;
 355                                 char date[FORMAT_TIMESTAMP_MAX];
 356
 357                                 if (!scheduled(&b.command)) {
 358                                         log_info("Shutdown canceled.");
 359                                         break;
 360                                 }
 361
 362                                 zero(its);
 363                                 if (b.command.warn_wall) {
 364                                         /* Send wall messages every so often */
 365                                         timespec_store(&its.it_value, when_wall(n, b.command.usec));
 366
 367                                         /* Warn immediately if less than 15 minutes are left */
 368                                         if (n < b.command.usec &&
 369                                             n + 15*USEC_PER_MINUTE >= b.command.usec)
 370                                                 warn_wall(n, &b.command);
 371                                 }
 372                                 if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 373                                         log_error("timerfd_settime(): %m");
 374                                         goto finish;
 375                                 }
 376
 377                                 /* Disallow logins 5 minutes prior to shutdown */
 378                                 zero(its);
 379                                 timespec_store(&its.it_value, when_nologin(b.command.usec));
 380                                 if (timerfd_settime(pollfd[FD_NOLOGIN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 381                                         log_error("timerfd_settime(): %m");
 382                                         goto finish;
 383                                 }
 384
 385                                 /* Shutdown after the specified time is reached */
 386                                 zero(its);
 387                                 timespec_store(&its.it_value, b.command.usec);
 388                                 if (timerfd_settime(pollfd[FD_SHUTDOWN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 389                                         log_error("timerfd_settime(): %m");
 390                                         goto finish;
 391                                 }
 392
 393                                 update_schedule_file(&b.command);
 394
 395                                 sd_notifyf(false,
 396                                            "STATUS=Shutting down at %s (%s)...",
 397                                            format_timestamp(date, sizeof(date), b.command.usec),
 398                                            mode_to_string(b.command.mode));
 399
 400                                 log_info("Shutting down at %s (%s)...", date, mode_to_string(b.command.mode));
 401                         }
 402                 }
 403
 404                 if (pollfd[FD_WALL_TIMER].revents) {
 405                         struct itimerspec its;
 406
 407                         warn_wall(n, &b.command);
 408                         flush_fd(pollfd[FD_WALL_TIMER].fd);
 409
 410                         /* Restart timer */
 411                         zero(its);
 412                         timespec_store(&its.it_value, when_wall(n, b.command.usec));
 413                         if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 414                                 log_error("timerfd_settime(): %m");
 415                                 goto finish;
 416                         }
 417                 }
 418
 419                 if (pollfd[FD_NOLOGIN_TIMER].revents) {
 420                         int e;
 421
 422                         log_info("Creating /run/nologin, blocking further logins...");
 423
 424                         e = write_one_line_file_atomic("/run/nologin", "System is going down.");
 425                         if (e < 0)
 426                                 log_error("Failed to create /run/nologin: %s", strerror(-e));
 427                         else
 428                                 unlink_nologin = true;
 429
 430                         flush_fd(pollfd[FD_NOLOGIN_TIMER].fd);
 431                 }
 432
 433                 if (pollfd[FD_SHUTDOWN_TIMER].revents) {
 434                         exec_shutdown = true;
 435                         goto finish;
 436                 }
 437         }
 438
 439         r = EXIT_SUCCESS;
 440
 441         log_debug("systemd-shutdownd stopped as pid %lu", (unsigned long) getpid());
 442
 443 finish:
 444
 445         for (i = 0; i < _FD_MAX; i++)
 446                 if (pollfd[i].fd >= 0)
 447                         close_nointr_nofail(pollfd[i].fd);
 448
 449         if (unlink_nologin)
 450                 unlink("/run/nologin");
 451
 452         unlink("/run/systemd/shutdown/scheduled");
 453
 454         if (exec_shutdown && !b.command.dry_run) {
 455                 char sw[3];
 456
 457                 sw[0] = '-';
 458                 sw[1] = b.command.mode;
 459                 sw[2] = 0;
 460
 461                 execl(SYSTEMCTL_BINARY_PATH,
 462                       "shutdown",
 463                       sw,
 464                       "now",
 465                       (b.command.warn_wall && b.command.wall_message[0]) ? b.command.wall_message :
 466                       (b.command.warn_wall ? NULL : "--no-wall"),
 467                       NULL);
 468
 469                 log_error("Failed to execute /sbin/shutdown: %m");
 470         }
 471
 472         sd_notify(false,
 473                   "STATUS=Exiting...");
 474
 475         return r;
 476 }