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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 "first_stage_init.h"
#include <dirent.h>
#include <fcntl.h>
#include <paths.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <sys/utsname.h>
#include <unistd.h>
#include <filesystem>
#include <string>
#include <vector>
#include <android-base/chrono_utils.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <modprobe/modprobe.h>
#include <private/android_filesystem_config.h>
#include "debug_ramdisk.h"
#include "first_stage_console.h"
#include "first_stage_mount.h"
#include "reboot_utils.h"
#include "second_stage_resources.h"
#include "snapuserd_transition.h"
#include "switch_root.h"
#include "util.h"
using android::base::boot_clock;
using namespace std::literals;
namespace fs = std::filesystem;
namespace android {
namespace init {
namespace {
void FreeRamdisk(DIR* dir, dev_t dev) {
int dfd = dirfd(dir);
dirent* de;
while ((de = readdir(dir)) != nullptr) {
if (de->d_name == "."s || de->d_name == ".."s) {
continue;
}
bool is_dir = false;
if (de->d_type == DT_DIR || de->d_type == DT_UNKNOWN) {
struct stat info;
if (fstatat(dfd, de->d_name, &info, AT_SYMLINK_NOFOLLOW) != 0) {
continue;
}
if (info.st_dev != dev) {
continue;
}
if (S_ISDIR(info.st_mode)) {
is_dir = true;
auto fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
if (fd >= 0) {
auto subdir =
std::unique_ptr<DIR, decltype(&closedir)>{fdopendir(fd), closedir};
if (subdir) {
FreeRamdisk(subdir.get(), dev);
} else {
close(fd);
}
}
}
} else if (de->d_type == DT_REG) {
// Do not free snapuserd if we will need the ramdisk copy during the
// selinux transition.
if (de->d_name == "snapuserd"s && IsFirstStageSnapuserdRunning()) {
continue;
}
}
unlinkat(dfd, de->d_name, is_dir ? AT_REMOVEDIR : 0);
}
}
bool ForceNormalBoot(const std::string& cmdline) {
return cmdline.find("androidboot.force_normal_boot=1") != std::string::npos;
}
} // namespace
std::string GetModuleLoadList(bool recovery, const std::string& dir_path) {
auto module_load_file = "modules.load";
if (recovery) {
struct stat fileStat;
std::string recovery_load_path = dir_path + "/modules.load.recovery";
if (!stat(recovery_load_path.c_str(), &fileStat)) {
module_load_file = "modules.load.recovery";
}
}
return module_load_file;
}
#define MODULE_BASE_DIR "/lib/modules"
bool LoadKernelModules(bool recovery, bool want_console) {
struct utsname uts;
if (uname(&uts)) {
LOG(FATAL) << "Failed to get kernel version.";
}
int major, minor;
if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) {
LOG(FATAL) << "Failed to parse kernel version " << uts.release;
}
std::unique_ptr<DIR, decltype(&closedir)> base_dir(opendir(MODULE_BASE_DIR), closedir);
if (!base_dir) {
LOG(INFO) << "Unable to open /lib/modules, skipping module loading.";
return true;
}
dirent* entry;
std::vector<std::string> module_dirs;
while ((entry = readdir(base_dir.get()))) {
if (entry->d_type != DT_DIR) {
continue;
}
int dir_major, dir_minor;
if (sscanf(entry->d_name, "%d.%d", &dir_major, &dir_minor) != 2 || dir_major != major ||
dir_minor != minor) {
continue;
}
module_dirs.emplace_back(entry->d_name);
}
// Sort the directories so they are iterated over during module loading
// in a consistent order. Alphabetical sorting is fine here because the
// kernel version at the beginning of the directory name must match the
// current kernel version, so the sort only applies to a label that
// follows the kernel version, for example /lib/modules/5.4 vs.
// /lib/modules/5.4-gki.
std::sort(module_dirs.begin(), module_dirs.end());
for (const auto& module_dir : module_dirs) {
std::string dir_path = MODULE_BASE_DIR "/";
dir_path.append(module_dir);
Modprobe m({dir_path}, GetModuleLoadList(recovery, dir_path));
bool retval = m.LoadListedModules(!want_console);
int modules_loaded = m.GetModuleCount();
if (modules_loaded > 0) {
return retval;
}
}
Modprobe m({MODULE_BASE_DIR}, GetModuleLoadList(recovery, MODULE_BASE_DIR));
bool retval = m.LoadListedModules(!want_console);
int modules_loaded = m.GetModuleCount();
if (modules_loaded > 0) {
return retval;
}
return true;
}
int FirstStageMain(int argc, char** argv) {
if (REBOOT_BOOTLOADER_ON_PANIC) {
InstallRebootSignalHandlers();
}
boot_clock::time_point start_time = boot_clock::now();
std::vector<std::pair<std::string, int>> errors;
#define CHECKCALL(x) \
if ((x) != 0) errors.emplace_back(#x " failed", errno);
// Clear the umask.
umask(0);
CHECKCALL(clearenv());
CHECKCALL(setenv("PATH", _PATH_DEFPATH, 1));
// Get the basic filesystem setup we need put together in the initramdisk
// on / and then we'll let the rc file figure out the rest.
CHECKCALL(mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755"));
CHECKCALL(mkdir("/dev/pts", 0755));
CHECKCALL(mkdir("/dev/socket", 0755));
CHECKCALL(mkdir("/dev/dm-user", 0755));
CHECKCALL(mount("devpts", "/dev/pts", "devpts", 0, NULL));
#define MAKE_STR(x) __STRING(x)
CHECKCALL(mount("proc", "/proc", "proc", 0, "hidepid=2,gid=" MAKE_STR(AID_READPROC)));
#undef MAKE_STR
// Don't expose the raw commandline to unprivileged processes.
CHECKCALL(chmod("/proc/cmdline", 0440));
std::string cmdline;
android::base::ReadFileToString("/proc/cmdline", &cmdline);
gid_t groups[] = {AID_READPROC};
CHECKCALL(setgroups(arraysize(groups), groups));
CHECKCALL(mount("sysfs", "/sys", "sysfs", 0, NULL));
CHECKCALL(mount("selinuxfs", "/sys/fs/selinux", "selinuxfs", 0, NULL));
CHECKCALL(mknod("/dev/kmsg", S_IFCHR | 0600, makedev(1, 11)));
if constexpr (WORLD_WRITABLE_KMSG) {
CHECKCALL(mknod("/dev/kmsg_debug", S_IFCHR | 0622, makedev(1, 11)));
}
CHECKCALL(mknod("/dev/random", S_IFCHR | 0666, makedev(1, 8)));
CHECKCALL(mknod("/dev/urandom", S_IFCHR | 0666, makedev(1, 9)));
// This is needed for log wrapper, which gets called before ueventd runs.
CHECKCALL(mknod("/dev/ptmx", S_IFCHR | 0666, makedev(5, 2)));
CHECKCALL(mknod("/dev/null", S_IFCHR | 0666, makedev(1, 3)));
// These below mounts are done in first stage init so that first stage mount can mount
// subdirectories of /mnt/{vendor,product}/. Other mounts, not required by first stage mount,
// should be done in rc files.
// Mount staging areas for devices managed by vold
// See storage config details at http://source.android.com/devices/storage/
CHECKCALL(mount("tmpfs", "/mnt", "tmpfs", MS_NOEXEC | MS_NOSUID | MS_NODEV,
"mode=0755,uid=0,gid=1000"));
// /mnt/vendor is used to mount vendor-specific partitions that can not be
// part of the vendor partition, e.g. because they are mounted read-write.
CHECKCALL(mkdir("/mnt/vendor", 0755));
// /mnt/product is used to mount product-specific partitions that can not be
// part of the product partition, e.g. because they are mounted read-write.
CHECKCALL(mkdir("/mnt/product", 0755));
// /debug_ramdisk is used to preserve additional files from the debug ramdisk
CHECKCALL(mount("tmpfs", "/debug_ramdisk", "tmpfs", MS_NOEXEC | MS_NOSUID | MS_NODEV,
"mode=0755,uid=0,gid=0"));
// /second_stage_resources is used to preserve files from first to second
// stage init
CHECKCALL(mount("tmpfs", kSecondStageRes, "tmpfs", MS_NOEXEC | MS_NOSUID | MS_NODEV,
"mode=0755,uid=0,gid=0"))
#undef CHECKCALL
SetStdioToDevNull(argv);
// Now that tmpfs is mounted on /dev and we have /dev/kmsg, we can actually
// talk to the outside world...
InitKernelLogging(argv);
if (!errors.empty()) {
for (const auto& [error_string, error_errno] : errors) {
LOG(ERROR) << error_string << " " << strerror(error_errno);
}
LOG(FATAL) << "Init encountered errors starting first stage, aborting";
}
LOG(INFO) << "init first stage started!";
auto old_root_dir = std::unique_ptr<DIR, decltype(&closedir)>{opendir("/"), closedir};
if (!old_root_dir) {
PLOG(ERROR) << "Could not opendir(\"/\"), not freeing ramdisk";
}
struct stat old_root_info;
if (stat("/", &old_root_info) != 0) {
PLOG(ERROR) << "Could not stat(\"/\"), not freeing ramdisk";
old_root_dir.reset();
}
auto want_console = ALLOW_FIRST_STAGE_CONSOLE ? FirstStageConsole(cmdline) : 0;
if (!LoadKernelModules(IsRecoveryMode() && !ForceNormalBoot(cmdline), want_console)) {
if (want_console != FirstStageConsoleParam::DISABLED) {
LOG(ERROR) << "Failed to load kernel modules, starting console";
} else {
LOG(FATAL) << "Failed to load kernel modules";
}
}
if (want_console == FirstStageConsoleParam::CONSOLE_ON_FAILURE) {
StartConsole(cmdline);
}
if (access(kBootImageRamdiskProp, F_OK) == 0) {
std::string dest = GetRamdiskPropForSecondStage();
std::string dir = android::base::Dirname(dest);
std::error_code ec;
if (!fs::create_directories(dir, ec) && !!ec) {
LOG(FATAL) << "Can't mkdir " << dir << ": " << ec.message();
}
if (!fs::copy_file(kBootImageRamdiskProp, dest, ec)) {
LOG(FATAL) << "Can't copy " << kBootImageRamdiskProp << " to " << dest << ": "
<< ec.message();
}
LOG(INFO) << "Copied ramdisk prop to " << dest;
}
if (ForceNormalBoot(cmdline)) {
mkdir("/first_stage_ramdisk", 0755);
// SwitchRoot() must be called with a mount point as the target, so we bind mount the
// target directory to itself here.
if (mount("/first_stage_ramdisk", "/first_stage_ramdisk", nullptr, MS_BIND, nullptr) != 0) {
LOG(FATAL) << "Could not bind mount /first_stage_ramdisk to itself";
}
SwitchRoot("/first_stage_ramdisk");
}
// If this file is present, the second-stage init will use a userdebug sepolicy
// and load adb_debug.prop to allow adb root, if the device is unlocked.
if (access("/force_debuggable", F_OK) == 0) {
std::error_code ec; // to invoke the overloaded copy_file() that won't throw.
if (!fs::copy_file("/adb_debug.prop", kDebugRamdiskProp, ec) ||
!fs::copy_file("/userdebug_plat_sepolicy.cil", kDebugRamdiskSEPolicy, ec)) {
LOG(ERROR) << "Failed to setup debug ramdisk";
} else {
// setenv for second-stage init to read above kDebugRamdisk* files.
setenv("INIT_FORCE_DEBUGGABLE", "true", 1);
}
}
if (!DoFirstStageMount()) {
LOG(FATAL) << "Failed to mount required partitions early ...";
}
struct stat new_root_info;
if (stat("/", &new_root_info) != 0) {
PLOG(ERROR) << "Could not stat(\"/\"), not freeing ramdisk";
old_root_dir.reset();
}
if (old_root_dir && old_root_info.st_dev != new_root_info.st_dev) {
FreeRamdisk(old_root_dir.get(), old_root_info.st_dev);
}
SetInitAvbVersionInRecovery();
setenv(kEnvFirstStageStartedAt, std::to_string(start_time.time_since_epoch().count()).c_str(),
1);
const char* path = "/system/bin/init";
const char* args[] = {path, "selinux_setup", nullptr};
auto fd = open("/dev/kmsg", O_WRONLY | O_CLOEXEC);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
close(fd);
execv(path, const_cast<char**>(args));
// execv() only returns if an error happened, in which case we
// panic and never fall through this conditional.
PLOG(FATAL) << "execv(\"" << path << "\") failed";
return 1;
}
} // namespace init
} // namespace android