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(struct shutdownd_command *c) {
 103
 104         assert(c);
 105         assert(c->warn_wall);
 106
 107         if (c->wall_message[0])
 108                 utmp_wall(c->wall_message);
 109         else {
 110                 char date[FORMAT_TIMESTAMP_MAX];
 111                 const char* prefix;
 112                 char *l;
 113
 114                 if (c->mode == 'H')
 115                         prefix = "The system is going down for system halt at";
 116                 else if (c->mode == 'P')
 117                         prefix = "The system is going down for power-off at";
 118                 else if (c->mode == 'r')
 119                         prefix = "The system is going down for reboot at";
 120                 else
 121                         assert_not_reached("Unknown mode!");
 122
 123                 if (asprintf(&l, "%s %s!",
 124                              prefix,
 125                              format_timestamp(date, sizeof(date), c->elapse)) < 0)
 126                         log_error("Failed to allocate wall message");
 127                 else {
 128                         utmp_wall(l);
 129                         free(l);
 130                 }
 131         }
 132 }
 133
 134 static usec_t when_wall(usec_t n, usec_t elapse) {
 135
 136         static const struct {
 137                 usec_t delay;
 138                 usec_t interval;
 139         } table[] = {
 140                 { 10 * USEC_PER_MINUTE, USEC_PER_MINUTE      },
 141                 { USEC_PER_HOUR,        15 * USEC_PER_MINUTE },
 142                 { 3 * USEC_PER_HOUR,    30 * USEC_PER_MINUTE }
 143         };
 144
 145         usec_t left, sub;
 146         unsigned i;
 147
 148         /* If the time is already passed, then don't announce */
 149         if (n >= elapse)
 150                 return 0;
 151
 152         left = elapse - n;
 153         for (i = 0; i < ELEMENTSOF(table); i++)
 154                 if (n + table[i].delay >= elapse)
 155                         sub = ((left / table[i].interval) * table[i].interval);
 156
 157         if (i >= ELEMENTSOF(table))
 158                 sub = ((left / USEC_PER_HOUR) * USEC_PER_HOUR);
 159
 160         return elapse > sub ? elapse - sub : 1;
 161 }
 162
 163 static usec_t when_nologin(usec_t elapse) {
 164         return elapse > 5*USEC_PER_MINUTE ? elapse - 5*USEC_PER_MINUTE : 1;
 165 }
 166
 167 int main(int argc, char *argv[]) {
 168         enum {
 169                 FD_SOCKET,
 170                 FD_WALL_TIMER,
 171                 FD_NOLOGIN_TIMER,
 172                 FD_SHUTDOWN_TIMER,
 173                 _FD_MAX
 174         };
 175
 176         int r = 4, n_fds;
 177         int one = 1;
 178         struct shutdownd_command c;
 179         struct pollfd pollfd[_FD_MAX];
 180         bool exec_shutdown = false, unlink_nologin = false, failed = false;
 181         unsigned i;
 182
 183         if (getppid() != 1) {
 184                 log_error("This program should be invoked by init only.");
 185                 return 1;
 186         }
 187
 188         if (argc > 1) {
 189                 log_error("This program does not take arguments.");
 190                 return 1;
 191         }
 192
 193         log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
 194         log_parse_environment();
 195
 196         if ((n_fds = sd_listen_fds(true)) < 0) {
 197                 log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
 198                 return 1;
 199         }
 200
 201         if (n_fds != 1) {
 202                 log_error("Need exactly one file descriptor.");
 203                 return 2;
 204         }
 205
 206         if (setsockopt(SD_LISTEN_FDS_START, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 207                 log_error("SO_PASSCRED failed: %m");
 208                 return 3;
 209         }
 210
 211         zero(c);
 212         zero(pollfd);
 213
 214         pollfd[FD_SOCKET].fd = SD_LISTEN_FDS_START;
 215         pollfd[FD_SOCKET].events = POLLIN;
 216
 217         for (i = 0; i < _FD_MAX; i++) {
 218
 219                 if (i == FD_SOCKET)
 220                         continue;
 221
 222                 pollfd[i].events = POLLIN;
 223
 224                 if ((pollfd[i].fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC)) < 0) {
 225                         log_error("timerfd_create(): %m");
 226                         failed = false;
 227                 }
 228         }
 229
 230         if (failed)
 231                 goto finish;
 232
 233         log_debug("systemd-shutdownd running as pid %lu", (unsigned long) getpid());
 234
 235         sd_notify(false,
 236                   "READY=1\n"
 237                   "STATUS=Processing requests...");
 238
 239         do {
 240                 int k;
 241                 usec_t n;
 242
 243                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 244
 245                         if (errno == EAGAIN || errno == EINTR)
 246                                 continue;
 247
 248                         log_error("poll(): %m");
 249                         goto finish;
 250                 }
 251
 252                 n = now(CLOCK_REALTIME);
 253
 254                 if (pollfd[FD_SOCKET].revents) {
 255
 256                         if ((k = read_packet(pollfd[FD_SOCKET].fd, &c)) < 0)
 257                                 goto finish;
 258                         else if (k > 0 && c.elapse > 0) {
 259                                 struct itimerspec its;
 260                                 char date[FORMAT_TIMESTAMP_MAX];
 261
 262                                 if (c.warn_wall) {
 263                                         /* Send wall messages every so often */
 264                                         zero(its);
 265                                         timespec_store(&its.it_value, when_wall(n, c.elapse));
 266                                         if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 267                                                 log_error("timerfd_settime(): %m");
 268                                                 goto finish;
 269                                         }
 270
 271                                         /* Warn immediately if less than 15 minutes are left */
 272                                         if (n < c.elapse &&
 273                                             n + 15*USEC_PER_MINUTE >= c.elapse)
 274                                                 warn_wall(&c);
 275                                 }
 276
 277                                 /* Disallow logins 5 minutes prior to shutdown */
 278                                 zero(its);
 279                                 timespec_store(&its.it_value, when_nologin(c.elapse));
 280                                 if (timerfd_settime(pollfd[FD_NOLOGIN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 281                                         log_error("timerfd_settime(): %m");
 282                                         goto finish;
 283                                 }
 284
 285                                 /* Shutdown after the specified time is reached */
 286                                 zero(its);
 287                                 timespec_store(&its.it_value, c.elapse);
 288                                 if (timerfd_settime(pollfd[FD_SHUTDOWN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 289                                         log_error("timerfd_settime(): %m");
 290                                         goto finish;
 291                                 }
 292
 293                                 sd_notifyf(false,
 294                                            "STATUS=Shutting down at %s...",
 295                                            format_timestamp(date, sizeof(date), c.elapse));
 296                         }
 297                 }
 298
 299                 if (pollfd[FD_WALL_TIMER].revents) {
 300                         struct itimerspec its;
 301
 302                         warn_wall(&c);
 303                         flush_fd(pollfd[FD_WALL_TIMER].fd);
 304
 305                         /* Restart timer */
 306                         zero(its);
 307                         timespec_store(&its.it_value, when_wall(n, c.elapse));
 308                         if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 309                                 log_error("timerfd_settime(): %m");
 310                                 goto finish;
 311                         }
 312                 }
 313
 314                 if (pollfd[FD_NOLOGIN_TIMER].revents) {
 315                         int e;
 316
 317                         if ((e = touch("/etc/nologin")) < 0)
 318                                 log_error("Failed to create /etc/nologin: %s", strerror(-e));
 319                         else
 320                                 unlink_nologin = true;
 321
 322                         flush_fd(pollfd[FD_NOLOGIN_TIMER].fd);
 323                 }
 324
 325                 if (pollfd[FD_SHUTDOWN_TIMER].revents) {
 326                         exec_shutdown = true;
 327                         goto finish;
 328                 }
 329
 330         } while (c.elapse > 0);
 331
 332         r = 0;
 333
 334         log_debug("systemd-shutdownd stopped as pid %lu", (unsigned long) getpid());
 335
 336 finish:
 337
 338         for (i = 0; i < _FD_MAX; i++)
 339                 if (pollfd[i].fd >= 0)
 340                         close_nointr_nofail(pollfd[i].fd);
 341
 342         if (exec_shutdown) {
 343                 char sw[3];
 344
 345                 sw[0] = '-';
 346                 sw[1] = c.mode;
 347                 sw[2] = 0;
 348
 349                 execl(SYSTEMCTL_BINARY_PATH, "shutdown", sw, "now", NULL);
 350                 log_error("Failed to execute /sbin/shutdown: %m");
 351         }
 352
 353         if (unlink_nologin)
 354                 unlink("/etc/nologin");
 355
 356         sd_notify(false,
 357                   "STATUS=Exiting...");
 358
 359         return r;
 360 }