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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <sys/capability.h>
#include <sys/reboot.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <optional>
#include <string>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/strings.h>
#include <backtrace/Backtrace.h>
#include <cutils/android_reboot.h>
#include "capabilities.h"
#include "reboot_utils.h"
#include "util.h"
namespace android {
namespace init {
static std::string init_fatal_reboot_target = "bootloader";
static bool init_fatal_panic = false;
// this needs to read the /proc/* files directly because it is called before
// ro.boot.* properties are initialized
void SetFatalRebootTarget(const std::optional<std::string>& reboot_target) {
std::string cmdline;
android::base::ReadFileToString("/proc/cmdline", &cmdline);
cmdline = android::base::Trim(cmdline);
const std::string kInitFatalPanicParamString = "androidboot.init_fatal_panic";
if (cmdline.find(kInitFatalPanicParamString) == std::string::npos) {
init_fatal_panic = false;
ImportBootconfig(
[kInitFatalPanicParamString](const std::string& key, const std::string& value) {
if (key == kInitFatalPanicParamString && value == "true") {
init_fatal_panic = true;
}
});
} else {
const std::string kInitFatalPanicString = kInitFatalPanicParamString + "=true";
init_fatal_panic = cmdline.find(kInitFatalPanicString) != std::string::npos;
}
if (reboot_target) {
init_fatal_reboot_target = *reboot_target;
return;
}
const std::string kRebootTargetString = "androidboot.init_fatal_reboot_target";
auto start_pos = cmdline.find(kRebootTargetString);
if (start_pos == std::string::npos) {
ImportBootconfig([kRebootTargetString](const std::string& key, const std::string& value) {
if (key == kRebootTargetString) {
init_fatal_reboot_target = value;
}
});
// We already default to bootloader if no setting is provided.
} else {
const std::string kRebootTargetStringPattern = kRebootTargetString + "=";
start_pos += sizeof(kRebootTargetStringPattern) - 1;
auto end_pos = cmdline.find(' ', start_pos);
// if end_pos isn't found, then we've run off the end, but this is okay as this is the last
// entry, and -1 is a valid size for string::substr();
auto size = end_pos == std::string::npos ? -1 : end_pos - start_pos;
init_fatal_reboot_target = cmdline.substr(start_pos, size);
}
}
bool IsRebootCapable() {
if (!CAP_IS_SUPPORTED(CAP_SYS_BOOT)) {
PLOG(WARNING) << "CAP_SYS_BOOT is not supported";
return true;
}
ScopedCaps caps(cap_get_proc());
if (!caps) {
PLOG(WARNING) << "cap_get_proc() failed";
return true;
}
cap_flag_value_t value = CAP_SET;
if (cap_get_flag(caps.get(), CAP_SYS_BOOT, CAP_EFFECTIVE, &value) != 0) {
PLOG(WARNING) << "cap_get_flag(CAP_SYS_BOOT, EFFECTIVE) failed";
return true;
}
return value == CAP_SET;
}
void __attribute__((noreturn)) RebootSystem(unsigned int cmd, const std::string& rebootTarget) {
LOG(INFO) << "Reboot ending, jumping to kernel";
if (!IsRebootCapable()) {
// On systems where init does not have the capability of rebooting the
// device, just exit cleanly.
exit(0);
}
switch (cmd) {
case ANDROID_RB_POWEROFF:
reboot(RB_POWER_OFF);
break;
case ANDROID_RB_RESTART2:
syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, rebootTarget.c_str());
break;
case ANDROID_RB_THERMOFF:
if (android::base::GetBoolProperty("ro.thermal_warmreset", false)) {
LOG(INFO) << "Try to trigger a warm reset for thermal shutdown";
static constexpr const char kThermalShutdownTarget[] = "shutdown,thermal";
syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, kThermalShutdownTarget);
} else {
reboot(RB_POWER_OFF);
}
break;
}
// In normal case, reboot should not return.
PLOG(ERROR) << "reboot call returned";
abort();
}
void __attribute__((noreturn)) InitFatalReboot(int signal_number) {
auto pid = fork();
if (pid == -1) {
// Couldn't fork, don't even try to backtrace, just reboot.
RebootSystem(ANDROID_RB_RESTART2, init_fatal_reboot_target);
} else if (pid == 0) {
// Fork a child for safety, since we always want to shut down if something goes wrong, but
// its worth trying to get the backtrace, even in the signal handler, since typically it
// does work despite not being async-signal-safe.
sleep(5);
RebootSystem(ANDROID_RB_RESTART2, init_fatal_reboot_target);
}
// In the parent, let's try to get a backtrace then shutdown.
LOG(ERROR) << __FUNCTION__ << ": signal " << signal_number;
std::unique_ptr<Backtrace> backtrace(
Backtrace::Create(BACKTRACE_CURRENT_PROCESS, BACKTRACE_CURRENT_THREAD));
if (!backtrace->Unwind(0)) {
LOG(ERROR) << __FUNCTION__ << ": Failed to unwind callstack.";
}
for (size_t i = 0; i < backtrace->NumFrames(); i++) {
LOG(ERROR) << backtrace->FormatFrameData(i);
}
if (init_fatal_panic) {
LOG(ERROR) << __FUNCTION__ << ": Trigger crash";
android::base::WriteStringToFile("c", PROC_SYSRQ);
LOG(ERROR) << __FUNCTION__ << ": Sys-Rq failed to crash the system; fallback to exit().";
_exit(signal_number);
}
RebootSystem(ANDROID_RB_RESTART2, init_fatal_reboot_target);
}
void InstallRebootSignalHandlers() {
// Instead of panic'ing the kernel as is the default behavior when init crashes,
// we prefer to reboot to bootloader on development builds, as this will prevent
// boot looping bad configurations and allow both developers and test farms to easily
// recover.
struct sigaction action;
memset(&action, 0, sizeof(action));
sigfillset(&action.sa_mask);
action.sa_handler = [](int signal) {
// These signal handlers are also caught for processes forked from init, however we do not
// want them to trigger reboot, so we directly call _exit() for children processes here.
if (getpid() != 1) {
_exit(signal);
}
// Calling DoReboot() or LOG(FATAL) is not a good option as this is a signal handler.
// RebootSystem uses syscall() which isn't actually async-signal-safe, but our only option
// and probably good enough given this is already an error case and only enabled for
// development builds.
InitFatalReboot(signal);
};
action.sa_flags = SA_RESTART;
sigaction(SIGABRT, &action, nullptr);
sigaction(SIGBUS, &action, nullptr);
sigaction(SIGFPE, &action, nullptr);
sigaction(SIGILL, &action, nullptr);
sigaction(SIGSEGV, &action, nullptr);
#if defined(SIGSTKFLT)
sigaction(SIGSTKFLT, &action, nullptr);
#endif
sigaction(SIGSYS, &action, nullptr);
sigaction(SIGTRAP, &action, nullptr);
}
} // namespace init
} // namespace android