platform_system_core/init/util.h
Tom Cherry 48e83e629f init: move InitKernelLogging() to first stage init
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.  InitKernelLogging()
is used to close these existing fds if they exist and replace them
with /dev/null.

Currently, InitKernelLogging() is only called in second stage init,
which means that processes exec'ed from first stage init will inherit
the kernel provided fds if any are provided.

In the case that they are provided, 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 moving InitKernelLogging() to first stage init is not
enough, since first stage init still runs in kernel context and future
child processes will not have permissions to access kernel context
resources.  Therefore, it must be done for a second time in second
stage init.

Bug: 117281017
Test: no audits when booting marlin.
Change-Id: If27edab5c32b27765e24c32fbed506ef625889de
2018-10-05 10:36:38 -07:00

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2.5 KiB
C++

/*
* Copyright (C) 2010 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.
*/
#ifndef _INIT_UTIL_H_
#define _INIT_UTIL_H_
#include <sys/stat.h>
#include <sys/types.h>
#include <chrono>
#include <functional>
#include <ostream>
#include <string>
#include <android-base/chrono_utils.h>
#include <selinux/label.h>
#include "result.h"
#define COLDBOOT_DONE "/dev/.coldboot_done"
using android::base::boot_clock;
using namespace std::chrono_literals;
namespace android {
namespace init {
int CreateSocket(const char* name, int type, bool passcred, mode_t perm, uid_t uid, gid_t gid,
const char* socketcon);
Result<std::string> ReadFile(const std::string& path);
Result<Success> WriteFile(const std::string& path, const std::string& content);
Result<uid_t> DecodeUid(const std::string& name);
bool mkdir_recursive(const std::string& pathname, mode_t mode);
int wait_for_file(const char *filename, std::chrono::nanoseconds timeout);
void import_kernel_cmdline(bool in_qemu,
const std::function<void(const std::string&, const std::string&, bool)>&);
bool make_dir(const std::string& path, mode_t mode);
std::string bytes_to_hex(const uint8_t *bytes, size_t bytes_len);
bool is_dir(const char* pathname);
bool expand_props(const std::string& src, std::string* dst);
// Returns the platform's Android DT directory as specified in the kernel cmdline.
// If the platform does not configure a custom DT path, returns the standard one (based in procfs).
const std::string& get_android_dt_dir();
// Reads or compares the content of device tree file under the platform's Android DT directory.
bool read_android_dt_file(const std::string& sub_path, std::string* dt_content);
bool is_android_dt_value_expected(const std::string& sub_path, const std::string& expected_content);
bool IsLegalPropertyName(const std::string& name);
void InitKernelLogging(char** argv, std::function<void(const char*)> abort_function);
} // namespace init
} // namespace android
#endif