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