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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <sys/reboot.h>
#include "crash-handler.h"
#include "exit-status.h"
#include "macro.h"
#include "main.h"
#include "missing_syscall.h"
#include "process-util.h"
#include "raw-clone.h"
#include "rlimit-util.h"
#include "signal-util.h"
#include "terminal-util.h"
#include "virt.h"
_noreturn_ void freeze_or_exit_or_reboot(void) {
/* If we are running in a container, let's prefer exiting, after all we can propagate an exit code to
* the container manager, and thus inform it that something went wrong. */
if (detect_container() > 0) {
log_emergency("Exiting PID 1...");
_exit(EXIT_EXCEPTION);
}
if (arg_crash_reboot) {
log_notice("Rebooting in 10s...");
(void) sleep(10);
log_notice("Rebooting now...");
(void) reboot(RB_AUTOBOOT);
log_emergency_errno(errno, "Failed to reboot: %m");
}
log_emergency("Freezing execution.");
sync();
freeze();
}
_noreturn_ static void crash(int sig, siginfo_t *siginfo, void *context) {
struct sigaction sa;
pid_t pid;
/* NB: 💣 💣 💣 This is a signal handler, most likely executed in a situation where we have corrupted
* memory. Thus: please avoid any libc memory allocation here, or any functions that internally use
* memory allocation, as we cannot rely on memory allocation still working at this point! (Note that
* memory allocation is not async-signal-safe anyway — see signal-safety(7) for details —, and thus
* is not permissible in signal handlers.) */
if (getpid_cached() != 1)
/* Pass this on immediately, if this is not PID 1 */
propagate_signal(sig, siginfo);
else if (!arg_dump_core)
log_emergency("Caught <%s>, not dumping core.", signal_to_string(sig));
else {
sa = (struct sigaction) {
.sa_handler = nop_signal_handler,
.sa_flags = SA_NOCLDSTOP|SA_RESTART,
};
/* We want to wait for the core process, hence let's enable SIGCHLD */
(void) sigaction(SIGCHLD, &sa, NULL);
pid = raw_clone(SIGCHLD);
if (pid < 0)
log_emergency_errno(errno, "Caught <%s>, cannot fork for core dump: %m", signal_to_string(sig));
else if (pid == 0) {
/* Enable default signal handler for core dump */
sa = (struct sigaction) {
.sa_handler = SIG_DFL,
};
(void) sigaction(sig, &sa, NULL);
/* Don't limit the coredump size */
(void) setrlimit(RLIMIT_CORE, &RLIMIT_MAKE_CONST(RLIM_INFINITY));
/* Just to be sure... */
(void) chdir("/");
/* Raise the signal again */
propagate_signal(sig, siginfo);
assert_not_reached();
_exit(EXIT_EXCEPTION);
} else {
siginfo_t status;
int r;
if (siginfo) {
if (siginfo->si_pid == 0)
log_emergency("Caught <%s> from unknown sender process.", signal_to_string(sig));
else if (siginfo->si_pid == 1)
log_emergency("Caught <%s> from our own process.", signal_to_string(sig));
else
log_emergency("Caught <%s> from PID "PID_FMT".", signal_to_string(sig), siginfo->si_pid);
}
/* Order things nicely. */
r = wait_for_terminate(pid, &status);
if (r < 0)
log_emergency_errno(r, "Caught <%s>, waitpid() failed: %m", signal_to_string(sig));
else if (status.si_code != CLD_DUMPED) {
const char *s = status.si_code == CLD_EXITED
? exit_status_to_string(status.si_status, EXIT_STATUS_LIBC)
: signal_to_string(status.si_status);
log_emergency("Caught <%s>, core dump failed (child "PID_FMT", code=%s, status=%i/%s).",
signal_to_string(sig),
pid,
sigchld_code_to_string(status.si_code),
status.si_status, strna(s));
} else
log_emergency("Caught <%s>, dumped core as pid "PID_FMT".",
signal_to_string(sig), pid);
}
}
if (arg_crash_chvt >= 0)
(void) chvt(arg_crash_chvt);
sa = (struct sigaction) {
.sa_handler = SIG_IGN,
.sa_flags = SA_NOCLDSTOP|SA_NOCLDWAIT|SA_RESTART,
};
/* Let the kernel reap children for us */
(void) sigaction(SIGCHLD, &sa, NULL);
if (arg_crash_shell) {
log_notice("Executing crash shell in 10s...");
(void) sleep(10);
pid = raw_clone(SIGCHLD);
if (pid < 0)
log_emergency_errno(errno, "Failed to fork off crash shell: %m");
else if (pid == 0) {
(void) setsid();
(void) make_console_stdio();
(void) rlimit_nofile_safe();
(void) execle("/bin/sh", "/bin/sh", NULL, environ);
log_emergency_errno(errno, "execle() failed: %m");
_exit(EXIT_EXCEPTION);
} else {
log_info("Spawned crash shell as PID "PID_FMT".", pid);
(void) wait_for_terminate(pid, NULL);
}
}
freeze_or_exit_or_reboot();
}
void install_crash_handler(void) {
static const struct sigaction sa = {
.sa_sigaction = crash,
.sa_flags = SA_NODEFER | SA_SIGINFO, /* So that we can raise the signal again from the signal handler */
};
int r;
/* We ignore the return value here, since, we don't mind if we cannot set up a crash handler */
r = sigaction_many(&sa, SIGNALS_CRASH_HANDLER);
if (r < 0)
log_debug_errno(r, "I had trouble setting up the crash handler, ignoring: %m");
}
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