platform_system_core/init/util.cpp
Jiyong Park 6866041ff0 Proper mount namespace configuration for bionic
This CL fixes the design problem of the previous mechanism for providing
the bootstrap bionic and the runtime bionic to the same path.

Previously, bootstrap bionic was self-bind-mounted; i.e.
/system/bin/libc.so is bind-mounted to itself. And the runtime bionic
was bind-mounted on top of the bootstrap bionic. This has not only caused
problems like `adb sync` not working(b/122737045), but also is quite
difficult to understand due to the double-and-self mounting.

This is the new design:

Most importantly, these four are all distinct:
1) bootstrap bionic (/system/lib/bootstrap/libc.so)
2) runtime bionic (/apex/com.android.runtime/lib/bionic/libc.so)
3) mount point for 1) and 2) (/bionic/lib/libc.so)
4) symlink for 3) (/system/lib/libc.so -> /bionic/lib/libc.so)

Inside the mount namespace of the pre-apexd processes, 1) is
bind-mounted to 3). Likewise, inside the mount namespace of the
post-apexd processes, 2) is bind-mounted to 3). In other words, there is
no self-mount, and no double-mount.

Another change is that mount points are under /bionic and the legacy
paths become symlinks to the mount points. This is to make sure that
there is no bind mounts under /system, which is breaking some apps.

Finally, code for creating mount namespaces, mounting bionic, etc are
refactored to mount_namespace.cpp

Bug: 120266448
Bug: 123275379
Test: m, device boots, adb sync/push/pull works,
especially with following paths:
/bionic/lib64/libc.so
/bionic/bin/linker64
/system/lib64/bootstrap/libc.so
/system/bin/bootstrap/linker64
Change-Id: Icdfbdcc1efca540ac854d4df79e07ee61fca559f
2019-01-30 19:18:22 +09:00

449 lines
14 KiB
C++

/*
* 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 <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/strings.h>
#include <android-base/unique_fd.h>
#include <cutils/sockets.h>
#include <selinux/android.h>
#if defined(__ANDROID__)
#include "selinux.h"
#else
#include "host_init_stubs.h"
#endif
#ifdef _INIT_INIT_H
#error "Do not include init.h in files used by ueventd; it will expose init's globals"
#endif
using android::base::boot_clock;
using namespace std::literals::string_literals;
namespace android {
namespace init {
const std::string kDefaultAndroidDtDir("/proc/device-tree/firmware/android/");
// 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").
*/
int CreateSocket(const char* name, int type, bool passcred, mode_t perm, uid_t uid, gid_t gid,
const char* socketcon) {
if (socketcon) {
if (setsockcreatecon(socketcon) == -1) {
PLOG(ERROR) << "setsockcreatecon(\"" << socketcon << "\") failed";
return -1;
}
}
android::base::unique_fd fd(socket(PF_UNIX, type, 0));
if (fd < 0) {
PLOG(ERROR) << "Failed to open socket '" << name << "'";
return -1;
}
if (socketcon) setsockcreatecon(NULL);
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);
if ((unlink(addr.sun_path) != 0) && (errno != ENOENT)) {
PLOG(ERROR) << "Failed to unlink old socket '" << name << "'";
return -1;
}
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))) {
PLOG(ERROR) << "Failed to set SO_PASSCRED '" << name << "'";
return -1;
}
}
int ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
int savederrno = errno;
if (!secontext.empty()) {
setfscreatecon(nullptr);
}
if (ret) {
errno = savederrno;
PLOG(ERROR) << "Failed to bind socket '" << name << "'";
goto out_unlink;
}
if (lchown(addr.sun_path, uid, gid)) {
PLOG(ERROR) << "Failed to lchown socket '" << addr.sun_path << "'";
goto out_unlink;
}
if (fchmodat(AT_FDCWD, addr.sun_path, perm, AT_SYMLINK_NOFOLLOW)) {
PLOG(ERROR) << "Failed to fchmodat socket '" << addr.sun_path << "'";
goto out_unlink;
}
LOG(INFO) << "Created socket '" << addr.sun_path << "'"
<< ", mode " << std::oct << perm << std::dec
<< ", user " << uid
<< ", group " << gid;
return fd.release();
out_unlink:
unlink(addr.sun_path);
return -1;
}
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<Success> 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 Success();
}
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 import_kernel_cmdline(bool in_qemu,
const std::function<void(const std::string&, const std::string&, bool)>& 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], in_qemu);
}
}
}
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);
}
bool expand_props(const std::string& src, std::string* dst) {
const char* src_ptr = src.c_str();
if (!dst) {
return false;
}
/* - 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 true;
}
dst->append(src_ptr, c);
c++;
if (*c == '$') {
dst->push_back(*(c++));
src_ptr = c;
continue;
} else if (*c == '\0') {
return true;
}
std::string prop_name;
std::string def_val;
if (*c == '{') {
c++;
const char* end = strchr(c, '}');
if (!end) {
// failed to find closing brace, abort.
LOG(ERROR) << "unexpected end of string in '" << src << "', looking for }";
return false;
}
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;
LOG(ERROR) << "using deprecated syntax for specifying property '" << c << "', use ${name} instead";
c += prop_name.size();
}
if (prop_name.empty()) {
LOG(ERROR) << "invalid zero-length property name in '" << src << "'";
return false;
}
std::string prop_val = android::base::GetProperty(prop_name, "");
if (prop_val.empty()) {
if (def_val.empty()) {
LOG(ERROR) << "property '" << prop_name << "' doesn't exist while expanding '" << src << "'";
return false;
}
prop_val = def_val;
}
dst->append(prop_val);
src_ptr = c;
}
return true;
}
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
import_kernel_cmdline(false,
[&](const std::string& key, const std::string& value, bool in_qemu) {
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;
}
void InitKernelLogging(char** argv, std::function<void(const char*)> abort_function) {
// Make stdin/stdout/stderr all point to /dev/null.
int fd = open("/dev/null", O_RDWR);
if (fd == -1) {
int saved_errno = errno;
android::base::InitLogging(argv, &android::base::KernelLogger, std::move(abort_function));
errno = saved_errno;
PLOG(FATAL) << "Couldn't open /dev/null";
}
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
if (fd > 2) close(fd);
android::base::InitLogging(argv, &android::base::KernelLogger, std::move(abort_function));
}
bool IsRecoveryMode() {
return access("/system/bin/recovery", F_OK) == 0;
}
} // namespace init
} // namespace android