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platform_system_core
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platform_system_core/init/util.cpp

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/*
* Copyright (C) 2008 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 "util.h"
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <time.h>
#include <unistd.h>
#include <thread>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/scopeguard.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <cutils/sockets.h>
#include <selinux/android.h>
#ifdef INIT_FULL_SOURCES
#include <android/api-level.h>
#include <sys/system_properties.h>
#include "reboot_utils.h"
#include "selabel.h"
#include "selinux.h"
#else
#include "host_init_stubs.h"
#endif
using android::base::boot_clock;
using android::base::StartsWith;
using namespace std::literals::string_literals;
namespace android {
namespace init {
const std::string kDefaultAndroidDtDir("/proc/device-tree/firmware/android/");
void (*trigger_shutdown)(const std::string& command) = nullptr;
// DecodeUid() - decodes and returns the given string, which can be either the
// numeric or name representation, into the integer uid or gid.
Result<uid_t> DecodeUid(const std::string& name) {
if (isalpha(name[0])) {
passwd* pwd = getpwnam(name.c_str());
if (!pwd) return ErrnoError() << "getpwnam failed";
return pwd->pw_uid;
}
errno = 0;
uid_t result = static_cast<uid_t>(strtoul(name.c_str(), 0, 0));
if (errno) return ErrnoError() << "strtoul failed";
return result;
}
/*
* CreateSocket - creates a Unix domain socket in ANDROID_SOCKET_DIR
* ("/dev/socket") as dictated in init.rc. This socket is inherited by the
* daemon. We communicate the file descriptor's value via the environment
* variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
*/
Result<int> CreateSocket(const std::string& name, int type, bool passcred, mode_t perm, uid_t uid,
gid_t gid, const std::string& socketcon) {
if (!socketcon.empty()) {
if (setsockcreatecon(socketcon.c_str()) == -1) {
return ErrnoError() << "setsockcreatecon(\"" << socketcon << "\") failed";
}
}
android::base::unique_fd fd(socket(PF_UNIX, type, 0));
if (fd < 0) {
return ErrnoError() << "Failed to open socket '" << name << "'";
}
if (!socketcon.empty()) setsockcreatecon(nullptr);
struct sockaddr_un addr;
memset(&addr, 0 , sizeof(addr));
addr.sun_family = AF_UNIX;
snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR "/%s", name.c_str());
if ((unlink(addr.sun_path) != 0) && (errno != ENOENT)) {
return ErrnoError() << "Failed to unlink old socket '" << name << "'";
}
std::string secontext;
if (SelabelLookupFileContext(addr.sun_path, S_IFSOCK, &secontext) && !secontext.empty()) {
setfscreatecon(secontext.c_str());
}
if (passcred) {
int on = 1;
if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on))) {
return ErrnoError() << "Failed to set SO_PASSCRED '" << name << "'";
}
}
int ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
int savederrno = errno;
if (!secontext.empty()) {
setfscreatecon(nullptr);
}
auto guard = android::base::make_scope_guard([&addr] { unlink(addr.sun_path); });
if (ret) {
errno = savederrno;
return ErrnoError() << "Failed to bind socket '" << name << "'";
}
if (lchown(addr.sun_path, uid, gid)) {
return ErrnoError() << "Failed to lchown socket '" << addr.sun_path << "'";
}
if (fchmodat(AT_FDCWD, addr.sun_path, perm, AT_SYMLINK_NOFOLLOW)) {
return ErrnoError() << "Failed to fchmodat socket '" << addr.sun_path << "'";
}
LOG(INFO) << "Created socket '" << addr.sun_path << "'"
<< ", mode " << std::oct << perm << std::dec
<< ", user " << uid
<< ", group " << gid;
guard.Disable();
return fd.release();
}
Result<std::string> ReadFile(const std::string& path) {
android::base::unique_fd fd(
TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC)));
if (fd == -1) {
return ErrnoError() << "open() failed";
}
// For security reasons, disallow world-writable
// or group-writable files.
struct stat sb;
if (fstat(fd, &sb) == -1) {
return ErrnoError() << "fstat failed()";
}
if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
return Error() << "Skipping insecure file";
}
std::string content;
if (!android::base::ReadFdToString(fd, &content)) {
return ErrnoError() << "Unable to read file contents";
}
return content;
}
static int OpenFile(const std::string& path, int flags, mode_t mode) {
std::string secontext;
if (SelabelLookupFileContext(path, mode, &secontext) && !secontext.empty()) {
setfscreatecon(secontext.c_str());
}
int rc = open(path.c_str(), flags, mode);
if (!secontext.empty()) {
int save_errno = errno;
setfscreatecon(nullptr);
errno = save_errno;
}
return rc;
}
Result<void> WriteFile(const std::string& path, const std::string& content) {
android::base::unique_fd fd(TEMP_FAILURE_RETRY(
OpenFile(path, O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0600)));
if (fd == -1) {
return ErrnoError() << "open() failed";
}
if (!android::base::WriteStringToFd(content, fd)) {
return ErrnoError() << "Unable to write file contents";
}
return {};
}
bool mkdir_recursive(const std::string& path, mode_t mode) {
std::string::size_type slash = 0;
while ((slash = path.find('/', slash + 1)) != std::string::npos) {
auto directory = path.substr(0, slash);
struct stat info;
if (stat(directory.c_str(), &info) != 0) {
auto ret = make_dir(directory, mode);
if (!ret && errno != EEXIST) return false;
}
}
auto ret = make_dir(path, mode);
if (!ret && errno != EEXIST) return false;
return true;
}
int wait_for_file(const char* filename, std::chrono::nanoseconds timeout) {
android::base::Timer t;
while (t.duration() < timeout) {
struct stat sb;
if (stat(filename, &sb) != -1) {
LOG(INFO) << "wait for '" << filename << "' took " << t;
return 0;
}
std::this_thread::sleep_for(10ms);
}
LOG(WARNING) << "wait for '" << filename << "' timed out and took " << t;
return -1;
}
void ImportKernelCmdline(const std::function<void(const std::string&, const std::string&)>& fn) {
std::string cmdline;
android::base::ReadFileToString("/proc/cmdline", &cmdline);
for (const auto& entry : android::base::Split(android::base::Trim(cmdline), " ")) {
std::vector<std::string> pieces = android::base::Split(entry, "=");
if (pieces.size() == 2) {
fn(pieces[0], pieces[1]);
}
}
}
bool make_dir(const std::string& path, mode_t mode) {
std::string secontext;
if (SelabelLookupFileContext(path, mode, &secontext) && !secontext.empty()) {
setfscreatecon(secontext.c_str());
}
int rc = mkdir(path.c_str(), mode);
if (!secontext.empty()) {
int save_errno = errno;
setfscreatecon(nullptr);
errno = save_errno;
}
return rc == 0;
}
/*
* Returns true is pathname is a directory
*/
bool is_dir(const char* pathname) {
struct stat info;
if (stat(pathname, &info) == -1) {
return false;
}
return S_ISDIR(info.st_mode);
}
Result<std::string> ExpandProps(const std::string& src) {
const char* src_ptr = src.c_str();
std::string dst;
/* - variables can either be $x.y or ${x.y}, in case they are only part
* of the string.
* - will accept $$ as a literal $.
* - no nested property expansion, i.e. ${foo.${bar}} is not supported,
* bad things will happen
* - ${x.y:-default} will return default value if property empty.
*/
while (*src_ptr) {
const char* c;
c = strchr(src_ptr, '$');
if (!c) {
dst.append(src_ptr);
return dst;
}
dst.append(src_ptr, c);
c++;
if (*c == '$') {
dst.push_back(*(c++));
src_ptr = c;
continue;
} else if (*c == '\0') {
return dst;
}
std::string prop_name;
std::string def_val;
if (*c == '{') {
c++;
const char* end = strchr(c, '}');
if (!end) {
// failed to find closing brace, abort.
return Error() << "unexpected end of string in '" << src << "', looking for }";
}
prop_name = std::string(c, end);
c = end + 1;
size_t def = prop_name.find(":-");
if (def < prop_name.size()) {
def_val = prop_name.substr(def + 2);
prop_name = prop_name.substr(0, def);
}
} else {
prop_name = c;
if (SelinuxGetVendorAndroidVersion() >= __ANDROID_API_R__) {
return Error() << "using deprecated syntax for specifying property '" << c
<< "', use ${name} instead";
} else {
LOG(ERROR) << "using deprecated syntax for specifying property '" << c
<< "', use ${name} instead";
}
c += prop_name.size();
}
if (prop_name.empty()) {
return Error() << "invalid zero-length property name in '" << src << "'";
}
std::string prop_val = android::base::GetProperty(prop_name, "");
if (prop_val.empty()) {
if (def_val.empty()) {
return Error() << "property '" << prop_name << "' doesn't exist while expanding '"
<< src << "'";
}
prop_val = def_val;
}
dst.append(prop_val);
src_ptr = c;
}
return dst;
}
static std::string init_android_dt_dir() {
// Use the standard procfs-based path by default
std::string android_dt_dir = kDefaultAndroidDtDir;
// The platform may specify a custom Android DT path in kernel cmdline
ImportKernelCmdline([&](const std::string& key, const std::string& value) {
if (key == "androidboot.android_dt_dir") {
android_dt_dir = value;
}
});
LOG(INFO) << "Using Android DT directory " << android_dt_dir;
return android_dt_dir;
}
// FIXME: The same logic is duplicated in system/core/fs_mgr/
const std::string& get_android_dt_dir() {
// Set once and saves time for subsequent calls to this function
static const std::string kAndroidDtDir = init_android_dt_dir();
return kAndroidDtDir;
}
// Reads the content of device tree file under the platform's Android DT directory.
// Returns true if the read is success, false otherwise.
bool read_android_dt_file(const std::string& sub_path, std::string* dt_content) {
const std::string file_name = get_android_dt_dir() + sub_path;
if (android::base::ReadFileToString(file_name, dt_content)) {
if (!dt_content->empty()) {
dt_content->pop_back(); // Trims the trailing '\0' out.
return true;
}
}
return false;
}
bool is_android_dt_value_expected(const std::string& sub_path, const std::string& expected_content) {
std::string dt_content;
if (read_android_dt_file(sub_path, &dt_content)) {
if (dt_content == expected_content) {
return true;
}
}
return false;
}
bool IsLegalPropertyName(const std::string& name) {
size_t namelen = name.size();
if (namelen < 1) return false;
if (name[0] == '.') return false;
if (name[namelen - 1] == '.') return false;
/* Only allow alphanumeric, plus '.', '-', '@', ':', or '_' */
/* Don't allow ".." to appear in a property name */
for (size_t i = 0; i < namelen; i++) {
if (name[i] == '.') {
// i=0 is guaranteed to never have a dot. See above.
if (name[i - 1] == '.') return false;
continue;
}
if (name[i] == '_' || name[i] == '-' || name[i] == '@' || name[i] == ':') continue;
if (name[i] >= 'a' && name[i] <= 'z') continue;
if (name[i] >= 'A' && name[i] <= 'Z') continue;
if (name[i] >= '0' && name[i] <= '9') continue;
return false;
}
return true;
}
Result<void> IsLegalPropertyValue(const std::string& name, const std::string& value) {
if (value.size() >= PROP_VALUE_MAX && !StartsWith(name, "ro.")) {
return Error() << "Property value too long";
}
if (mbstowcs(nullptr, value.data(), 0) == static_cast<std::size_t>(-1)) {
return Error() << "Value is not a UTF8 encoded string";
}
return {};
}
static FscryptAction FscryptInferAction(const std::string& dir) {
const std::string prefix = "/data/";
if (!android::base::StartsWith(dir, prefix)) {
return FscryptAction::kNone;
}
// Special-case /data/media/obb per b/64566063
if (dir == "/data/media/obb") {
// Try to set policy on this directory, but if it is non-empty this may fail.
return FscryptAction::kAttempt;
}
// Only set policy on first level /data directories
// To make this less restrictive, consider using a policy file.
// However this is overkill for as long as the policy is simply
// to apply a global policy to all /data folders created via makedir
if (dir.find_first_of('/', prefix.size()) != std::string::npos) {
return FscryptAction::kNone;
}
// Special case various directories that must not be encrypted,
// often because their subdirectories must be encrypted.
// This isn't a nice way to do this, see b/26641735
std::vector<std::string> directories_to_exclude = {
"lost+found", "system_ce", "system_de", "misc_ce", "misc_de",
"vendor_ce", "vendor_de", "media", "data", "user",
"user_de", "apex", "preloads", "app-staging", "gsi",
};
for (const auto& d : directories_to_exclude) {
if ((prefix + d) == dir) {
return FscryptAction::kNone;
}
}
// Empty these directories if policy setting fails.
std::vector<std::string> wipe_on_failure = {
"rollback", "rollback-observer", // b/139193659
};
for (const auto& d : wipe_on_failure) {
if ((prefix + d) == dir) {
return FscryptAction::kDeleteIfNecessary;
}
}
return FscryptAction::kRequire;
}
Result<MkdirOptions> ParseMkdir(const std::vector<std::string>& args) {
mode_t mode = 0755;
Result<uid_t> uid = -1;
Result<gid_t> gid = -1;
FscryptAction fscrypt_inferred_action = FscryptInferAction(args[1]);
FscryptAction fscrypt_action = fscrypt_inferred_action;
std::string ref_option = "ref";
bool set_option_encryption = false;
bool set_option_key = false;
for (size_t i = 2; i < args.size(); i++) {
switch (i) {
case 2:
mode = std::strtoul(args[2].c_str(), 0, 8);
break;
case 3:
uid = DecodeUid(args[3]);
if (!uid.ok()) {
return Error()
<< "Unable to decode UID for '" << args[3] << "': " << uid.error();
}
break;
case 4:
gid = DecodeUid(args[4]);
if (!gid.ok()) {
return Error()
<< "Unable to decode GID for '" << args[4] << "': " << gid.error();
}
break;
default:
auto parts = android::base::Split(args[i], "=");
if (parts.size() != 2) {
return Error() << "Can't parse option: '" << args[i] << "'";
}
auto optname = parts[0];
auto optval = parts[1];
if (optname == "encryption") {
if (set_option_encryption) {
return Error() << "Duplicated option: '" << optname << "'";
}
if (optval == "Require") {
fscrypt_action = FscryptAction::kRequire;
} else if (optval == "None") {
fscrypt_action = FscryptAction::kNone;
} else if (optval == "Attempt") {
fscrypt_action = FscryptAction::kAttempt;
} else if (optval == "DeleteIfNecessary") {
fscrypt_action = FscryptAction::kDeleteIfNecessary;
} else {
return Error() << "Unknown encryption option: '" << optval << "'";
}
set_option_encryption = true;
} else if (optname == "key") {
if (set_option_key) {
return Error() << "Duplicated option: '" << optname << "'";
}
if (optval == "ref" || optval == "per_boot_ref") {
ref_option = optval;
} else {
return Error() << "Unknown key option: '" << optval << "'";
}
set_option_key = true;
} else {
return Error() << "Unknown option: '" << args[i] << "'";
}
}
}
if (set_option_key && fscrypt_action == FscryptAction::kNone) {
return Error() << "Key option set but encryption action is none";
}
const std::string prefix = "/data/";
if (StartsWith(args[1], prefix) &&
args[1].find_first_of('/', prefix.size()) == std::string::npos) {
if (!set_option_encryption) {
LOG(WARNING) << "Top-level directory needs encryption action, eg mkdir " << args[1]
<< " <mode> <uid> <gid> encryption=Require";
}
if (fscrypt_action == FscryptAction::kNone) {
LOG(INFO) << "Not setting encryption policy on: " << args[1];
}
}
if (fscrypt_action != fscrypt_inferred_action) {
LOG(WARNING) << "Inferred action different from explicit one, expected "
<< static_cast<int>(fscrypt_inferred_action) << " but got "
<< static_cast<int>(fscrypt_action);
}
return MkdirOptions{args[1], mode, *uid, *gid, fscrypt_action, ref_option};
}
Result<MountAllOptions> ParseMountAll(const std::vector<std::string>& args) {
bool compat_mode = false;
bool import_rc = false;
if (SelinuxGetVendorAndroidVersion() <= __ANDROID_API_Q__) {
if (args.size() <= 1) {
return Error() << "mount_all requires at least 1 argument";
}
compat_mode = true;
import_rc = true;
}
std::size_t first_option_arg = args.size();
enum mount_mode mode = MOUNT_MODE_DEFAULT;
// If we are <= Q, then stop looking for non-fstab arguments at slot 2.
// Otherwise, stop looking at slot 1 (as the fstab path argument is optional >= R).
for (std::size_t na = args.size() - 1; na > (compat_mode ? 1 : 0); --na) {
if (args[na] == "--early") {
first_option_arg = na;
mode = MOUNT_MODE_EARLY;
} else if (args[na] == "--late") {
first_option_arg = na;
mode = MOUNT_MODE_LATE;
import_rc = false;
}
}
std::string fstab_path;
if (first_option_arg > 1) {
fstab_path = args[1];
} else if (compat_mode) {
return Error() << "mount_all argument 1 must be the fstab path";
}
std::vector<std::string> rc_paths;
for (std::size_t na = 2; na < first_option_arg; ++na) {
rc_paths.push_back(args[na]);
}
return MountAllOptions{rc_paths, fstab_path, mode, import_rc};
}
Result<std::pair<int, std::vector<std::string>>> ParseRestorecon(
const std::vector<std::string>& args) {
struct flag_type {
const char* name;
int value;
};
static const flag_type flags[] = {
{"--recursive", SELINUX_ANDROID_RESTORECON_RECURSE},
{"--skip-ce", SELINUX_ANDROID_RESTORECON_SKIPCE},
{"--cross-filesystems", SELINUX_ANDROID_RESTORECON_CROSS_FILESYSTEMS},
{0, 0}};
int flag = 0;
std::vector<std::string> paths;
bool in_flags = true;
for (size_t i = 1; i < args.size(); ++i) {
if (android::base::StartsWith(args[i], "--")) {
if (!in_flags) {
return Error() << "flags must precede paths";
}
bool found = false;
for (size_t j = 0; flags[j].name; ++j) {
if (args[i] == flags[j].name) {
flag |= flags[j].value;
found = true;
break;
}
}
if (!found) {
return Error() << "bad flag " << args[i];
}
} else {
in_flags = false;
paths.emplace_back(args[i]);
}
}
return std::pair(flag, paths);
}
Result<std::string> ParseSwaponAll(const std::vector<std::string>& args) {
if (args.size() <= 1) {
if (SelinuxGetVendorAndroidVersion() <= __ANDROID_API_Q__) {
return Error() << "swapon_all requires at least 1 argument";
}
return {};
}
return args[1];
}
Result<std::string> ParseUmountAll(const std::vector<std::string>& args) {
if (args.size() <= 1) {
if (SelinuxGetVendorAndroidVersion() <= __ANDROID_API_Q__) {
return Error() << "umount_all requires at least 1 argument";
}
return {};
}
return args[1];
}
static void InitAborter(const char* abort_message) {
// When init forks, it continues to use this aborter for LOG(FATAL), but we want children to
// simply abort instead of trying to reboot the system.
if (getpid() != 1) {
android::base::DefaultAborter(abort_message);
return;
}
InitFatalReboot(SIGABRT);
}
// The kernel opens /dev/console and uses that fd for stdin/stdout/stderr if there is a serial
// console enabled and no initramfs, otherwise it does not provide any fds for stdin/stdout/stderr.
// SetStdioToDevNull() is used to close these existing fds if they exist and replace them with
// /dev/null regardless.
//
// In the case that these fds are provided by the kernel, the exec of second stage init causes an
// SELinux denial as it does not have access to /dev/console. In the case that they are not
// provided, exec of any further process is potentially dangerous as the first fd's opened by that
// process will take the stdin/stdout/stderr fileno's, which can cause issues if printf(), etc is
// then used by that process.
//
// Lastly, simply calling SetStdioToDevNull() in first stage init is not enough, since first
// stage init still runs in kernel context, future child processes will not have permissions to
// access any fds that it opens, including the one opened below for /dev/null. Therefore,
// SetStdioToDevNull() must be called again in second stage init.
void SetStdioToDevNull(char** argv) {
// Make stdin/stdout/stderr all point to /dev/null.
int fd = open("/dev/null", O_RDWR); // NOLINT(android-cloexec-open)
if (fd == -1) {
int saved_errno = errno;
android::base::InitLogging(argv, &android::base::KernelLogger, InitAborter);
errno = saved_errno;
PLOG(FATAL) << "Couldn't open /dev/null";
}
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
if (fd > STDERR_FILENO) close(fd);
}
void InitKernelLogging(char** argv) {
SetFatalRebootTarget();
android::base::InitLogging(argv, &android::base::KernelLogger, InitAborter);
}
bool IsRecoveryMode() {
return access("/system/bin/recovery", F_OK) == 0;
}
} // namespace init
} // namespace android
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