201 lines
7.7 KiB
C
201 lines
7.7 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <sys/ioctl.h>
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#include <sys/reboot.h>
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#include <sys/wait.h>
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#include <sys/prctl.h>
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#include <unistd.h>
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#include "def.h"
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#include "exit-status.h"
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#include "fd-util.h"
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#include "log.h"
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#include "nspawn-stub-pid1.h"
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#include "process-util.h"
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#include "signal-util.h"
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#include "time-util.h"
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static int reset_environ(const char *new_environment, size_t length) {
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unsigned long start, end;
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start = (unsigned long) new_environment;
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end = start + length;
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_START, start, 0, 0) < 0)
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return -errno;
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_END, end, 0, 0) < 0)
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return -errno;
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return 0;
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}
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int stub_pid1(sd_id128_t uuid) {
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enum {
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STATE_RUNNING,
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STATE_REBOOT,
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STATE_POWEROFF,
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} state = STATE_RUNNING;
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sigset_t fullmask, oldmask, waitmask;
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usec_t quit_usec = USEC_INFINITY;
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pid_t pid;
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int r;
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/* The new environment we set up, on the stack. */
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char new_environment[] =
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"container=systemd-nspawn\0"
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"container_uuid=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
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/* Implements a stub PID 1, that reaps all processes and processes a couple of standard signals. This is useful
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* for allowing arbitrary processes run in a container, and still have all zombies reaped. */
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assert_se(sigfillset(&fullmask) >= 0);
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assert_se(sigprocmask(SIG_BLOCK, &fullmask, &oldmask) >= 0);
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pid = fork();
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if (pid < 0)
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return log_error_errno(errno, "Failed to fork child pid: %m");
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if (pid == 0) {
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/* Return in the child */
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assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) >= 0);
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if (setsid() < 0)
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return log_error_errno(errno, "Failed to become session leader in payload process: %m");
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return 0;
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}
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reset_all_signal_handlers();
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log_close();
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(void) close_all_fds(NULL, 0);
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log_open();
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if (ioctl(STDIN_FILENO, TIOCNOTTY) < 0) {
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if (errno != ENOTTY)
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log_warning_errno(errno, "Unexpected error from TIOCNOTTY ioctl in init stub process, ignoring: %m");
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} else
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log_warning("Expected TIOCNOTTY to fail, but it succeeded in init stub process, ignoring.");
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/* Flush out /proc/self/environ, so that we don't leak the environment from the host into the container. Also,
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* set $container= and $container_uuid= so that clients in the container that query it from /proc/1/environ
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* find them set. */
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sd_id128_to_string(uuid, new_environment + sizeof(new_environment) - SD_ID128_STRING_MAX);
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reset_environ(new_environment, sizeof(new_environment));
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(void) rename_process("(sd-stubinit)");
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assert_se(sigemptyset(&waitmask) >= 0);
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assert_se(sigset_add_many(&waitmask,
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SIGCHLD, /* posix: process died */
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SIGINT, /* sysv: ctrl-alt-del */
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SIGRTMIN+3, /* systemd: halt */
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SIGRTMIN+4, /* systemd: poweroff */
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SIGRTMIN+5, /* systemd: reboot */
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SIGRTMIN+6, /* systemd: kexec */
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SIGRTMIN+13, /* systemd: halt */
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SIGRTMIN+14, /* systemd: poweroff */
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SIGRTMIN+15, /* systemd: reboot */
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SIGRTMIN+16, /* systemd: kexec */
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-1) >= 0);
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/* Note that we ignore SIGTERM (sysv's reexec), SIGHUP (reload), and all other signals here, since we don't
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* support reexec/reloading in this stub process. */
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for (;;) {
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siginfo_t si;
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usec_t current_usec;
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si.si_pid = 0;
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r = waitid(P_ALL, 0, &si, WEXITED|WNOHANG);
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if (r < 0) {
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r = log_error_errno(errno, "Failed to reap children: %m");
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goto finish;
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}
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current_usec = now(CLOCK_MONOTONIC);
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if (si.si_pid == pid || current_usec >= quit_usec) {
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/* The child we started ourselves died or we reached a timeout. */
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if (state == STATE_REBOOT) { /* dispatch a queued reboot */
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(void) reboot(RB_AUTOBOOT);
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r = log_error_errno(errno, "Failed to reboot: %m");
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goto finish;
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} else if (state == STATE_POWEROFF)
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(void) reboot(RB_POWER_OFF); /* if this fails, fall back to normal exit. */
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if (si.si_pid == pid && si.si_code == CLD_EXITED)
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r = si.si_status; /* pass on exit code */
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else
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r = EXIT_EXCEPTION; /* signal, coredump, timeout, … */
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goto finish;
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}
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if (si.si_pid != 0)
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/* We reaped something. Retry until there's nothing more to reap. */
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continue;
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if (quit_usec == USEC_INFINITY)
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r = sigwaitinfo(&waitmask, &si);
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else {
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struct timespec ts;
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r = sigtimedwait(&waitmask, &si, timespec_store(&ts, quit_usec - current_usec));
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}
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if (r < 0) {
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if (errno == EINTR) /* strace -p attach can result in EINTR, let's handle this nicely. */
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continue;
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if (errno == EAGAIN) /* timeout reached */
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continue;
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r = log_error_errno(errno, "Failed to wait for signal: %m");
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goto finish;
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}
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if (si.si_signo == SIGCHLD)
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continue; /* Let's reap this */
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if (state != STATE_RUNNING)
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continue;
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/* Would love to use a switch() statement here, but SIGRTMIN is actually a function call, not a
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* constant… */
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if (si.si_signo == SIGRTMIN+3 ||
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si.si_signo == SIGRTMIN+4 ||
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si.si_signo == SIGRTMIN+13 ||
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si.si_signo == SIGRTMIN+14)
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state = STATE_POWEROFF;
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else if (si.si_signo == SIGINT ||
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si.si_signo == SIGRTMIN+5 ||
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si.si_signo == SIGRTMIN+6 ||
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si.si_signo == SIGRTMIN+15 ||
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si.si_signo == SIGRTMIN+16)
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state = STATE_REBOOT;
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else
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assert_not_reached("Got unexpected signal");
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r = kill_and_sigcont(pid, SIGTERM);
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/* Let's send a SIGHUP after the SIGTERM, as shells tend to ignore SIGTERM but do react to SIGHUP. We
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* do it strictly in this order, so that the SIGTERM is dispatched first, and SIGHUP second for those
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* processes which handle both. That's because services tend to bind configuration reload or something
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* else to SIGHUP. */
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if (r != -ESRCH)
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(void) kill(pid, SIGHUP);
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quit_usec = now(CLOCK_MONOTONIC) + DEFAULT_TIMEOUT_USEC;
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}
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finish:
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_exit(r < 0 ? EXIT_FAILURE : r);
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}
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