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
 104         assert(c);
 105         assert(c->warn_wall);
 106
 107         if (n >= c->elapse)
 108                 return;
 109
 110         if (c->wall_message[0])
 111                 utmp_wall(c->wall_message);
 112         else {
 113                 char date[FORMAT_TIMESTAMP_MAX];
 114                 const char* prefix;
 115                 char *l = NULL;
 116
 117                 if (c->mode == 'H')
 118                         prefix = "The system is going down for system halt at ";
 119                 else if (c->mode == 'P')
 120                         prefix = "The system is going down for power-off at ";
 121                 else if (c->mode == 'r')
 122                         prefix = "The system is going down for reboot at ";
 123                 else
 124                         assert_not_reached("Unknown mode!");
 125
 126                 if (asprintf(&l, "%s%s!", prefix, format_timestamp(date, sizeof(date), c->elapse)) < 0)
 127                         log_error("Failed to allocate wall message");
 128                 else {
 129                         utmp_wall(l);
 130                         free(l);
 131                 }
 132         }
 133 }
 134
 135 static usec_t when_wall(usec_t n, usec_t elapse) {
 136
 137         static const struct {
 138                 usec_t delay;
 139                 usec_t interval;
 140         } table[] = {
 141                 { 10 * USEC_PER_MINUTE, USEC_PER_MINUTE      },
 142                 { USEC_PER_HOUR,        15 * USEC_PER_MINUTE },
 143                 { 3 * USEC_PER_HOUR,    30 * USEC_PER_MINUTE }
 144         };
 145
 146         usec_t left, sub;
 147         unsigned i;
 148
 149         /* If the time is already passed, then don't announce */
 150         if (n >= elapse)
 151                 return 0;
 152
 153         left = elapse - n;
 154         for (i = 0; i < ELEMENTSOF(table); i++)
 155                 if (n + table[i].delay >= elapse) {
 156                         sub = ((left / table[i].interval) * table[i].interval);
 157                         break;
 158                 }
 159
 160         if (i >= ELEMENTSOF(table))
 161                 sub = ((left / USEC_PER_HOUR) * USEC_PER_HOUR);
 162
 163         return elapse > sub ? elapse - sub : 1;
 164 }
 165
 166 static usec_t when_nologin(usec_t elapse) {
 167         return elapse > 5*USEC_PER_MINUTE ? elapse - 5*USEC_PER_MINUTE : 1;
 168 }
 169
 170 int main(int argc, char *argv[]) {
 171         enum {
 172                 FD_SOCKET,
 173                 FD_WALL_TIMER,
 174                 FD_NOLOGIN_TIMER,
 175                 FD_SHUTDOWN_TIMER,
 176                 _FD_MAX
 177         };
 178
 179         int r = EXIT_FAILURE, n_fds;
 180         int one = 1;
 181         struct shutdownd_command c;
 182         struct pollfd pollfd[_FD_MAX];
 183         bool exec_shutdown = false, unlink_nologin = false, failed = false;
 184         unsigned i;
 185
 186         if (getppid() != 1) {
 187                 log_error("This program should be invoked by init only.");
 188                 return EXIT_FAILURE;
 189         }
 190
 191         if (argc > 1) {
 192                 log_error("This program does not take arguments.");
 193                 return EXIT_FAILURE;
 194         }
 195
 196         log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
 197         log_parse_environment();
 198         log_open();
 199
 200         if ((n_fds = sd_listen_fds(true)) < 0) {
 201                 log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
 202                 return EXIT_FAILURE;
 203         }
 204
 205         if (n_fds != 1) {
 206                 log_error("Need exactly one file descriptor.");
 207                 return EXIT_FAILURE;
 208         }
 209
 210         if (setsockopt(SD_LISTEN_FDS_START, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 211                 log_error("SO_PASSCRED failed: %m");
 212                 return EXIT_FAILURE;
 213         }
 214
 215         zero(c);
 216         zero(pollfd);
 217
 218         pollfd[FD_SOCKET].fd = SD_LISTEN_FDS_START;
 219         pollfd[FD_SOCKET].events = POLLIN;
 220
 221         for (i = 0; i < _FD_MAX; i++) {
 222
 223                 if (i == FD_SOCKET)
 224                         continue;
 225
 226                 pollfd[i].events = POLLIN;
 227
 228                 if ((pollfd[i].fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC)) < 0) {
 229                         log_error("timerfd_create(): %m");
 230                         failed = false;
 231                 }
 232         }
 233
 234         if (failed)
 235                 goto finish;
 236
 237         log_debug("systemd-shutdownd running as pid %lu", (unsigned long) getpid());
 238
 239         sd_notify(false,
 240                   "READY=1\n"
 241                   "STATUS=Processing requests...");
 242
 243         do {
 244                 int k;
 245                 usec_t n;
 246
 247                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 248
 249                         if (errno == EAGAIN || errno == EINTR)
 250                                 continue;
 251
 252                         log_error("poll(): %m");
 253                         goto finish;
 254                 }
 255
 256                 n = now(CLOCK_REALTIME);
 257
 258                 if (pollfd[FD_SOCKET].revents) {
 259
 260                         if ((k = read_packet(pollfd[FD_SOCKET].fd, &c)) < 0)
 261                                 goto finish;
 262                         else if (k > 0 && c.elapse > 0) {
 263                                 struct itimerspec its;
 264                                 char date[FORMAT_TIMESTAMP_MAX];
 265
 266                                 if (c.warn_wall) {
 267                                         /* Send wall messages every so often */
 268                                         zero(its);
 269                                         timespec_store(&its.it_value, when_wall(n, c.elapse));
 270                                         if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 271                                                 log_error("timerfd_settime(): %m");
 272                                                 goto finish;
 273                                         }
 274
 275                                         /* Warn immediately if less than 15 minutes are left */
 276                                         if (n < c.elapse &&
 277                                             n + 15*USEC_PER_MINUTE >= c.elapse)
 278                                                 warn_wall(n, &c);
 279                                 }
 280
 281                                 /* Disallow logins 5 minutes prior to shutdown */
 282                                 zero(its);
 283                                 timespec_store(&its.it_value, when_nologin(c.elapse));
 284                                 if (timerfd_settime(pollfd[FD_NOLOGIN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 285                                         log_error("timerfd_settime(): %m");
 286                                         goto finish;
 287                                 }
 288
 289                                 /* Shutdown after the specified time is reached */
 290                                 zero(its);
 291                                 timespec_store(&its.it_value, c.elapse);
 292                                 if (timerfd_settime(pollfd[FD_SHUTDOWN_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 293                                         log_error("timerfd_settime(): %m");
 294                                         goto finish;
 295                                 }
 296
 297                                 sd_notifyf(false,
 298                                            "STATUS=Shutting down at %s...",
 299                                            format_timestamp(date, sizeof(date), c.elapse));
 300                         }
 301                 }
 302
 303                 if (pollfd[FD_WALL_TIMER].revents) {
 304                         struct itimerspec its;
 305
 306                         warn_wall(n, &c);
 307                         flush_fd(pollfd[FD_WALL_TIMER].fd);
 308
 309                         /* Restart timer */
 310                         zero(its);
 311                         timespec_store(&its.it_value, when_wall(n, c.elapse));
 312                         if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
 313                                 log_error("timerfd_settime(): %m");
 314                                 goto finish;
 315                         }
 316                 }
 317
 318                 if (pollfd[FD_NOLOGIN_TIMER].revents) {
 319                         int e;
 320
 321                         log_info("Creating /etc/nologin, blocking further logins...");
 322
 323                         if ((e = touch("/etc/nologin")) < 0)
 324                                 log_error("Failed to create /etc/nologin: %s", strerror(-e));
 325                         else
 326                                 unlink_nologin = true;
 327
 328                         flush_fd(pollfd[FD_NOLOGIN_TIMER].fd);
 329                 }
 330
 331                 if (pollfd[FD_SHUTDOWN_TIMER].revents) {
 332                         exec_shutdown = true;
 333                         goto finish;
 334                 }
 335
 336         } while (c.elapse > 0);
 337
 338         r = EXIT_SUCCESS;
 339
 340         log_debug("systemd-shutdownd stopped as pid %lu", (unsigned long) getpid());
 341
 342 finish:
 343
 344         for (i = 0; i < _FD_MAX; i++)
 345                 if (pollfd[i].fd >= 0)
 346                         close_nointr_nofail(pollfd[i].fd);
 347
 348         if (unlink_nologin)
 349                 unlink("/etc/nologin");
 350
 351         if (exec_shutdown) {
 352                 char sw[3];
 353
 354                 sw[0] = '-';
 355                 sw[1] = c.mode;
 356                 sw[2] = 0;
 357
 358                 execl(SYSTEMCTL_BINARY_PATH,
 359                       "shutdown",
 360                       sw,
 361                       "now",
 362                       (c.warn_wall && c.wall_message[0]) ? c.wall_message :
 363                       (c.warn_wall ? NULL : "--no-wall"),
 364                       NULL);
 365
 366                 log_error("Failed to execute /sbin/shutdown: %m");
 367         }
 368
 369         sd_notify(false,
 370                   "STATUS=Exiting...");
 371
 372         return r;
 373 }