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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "sandbox/linux/seccomp-bpf/die.h"
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <sys/prctl.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <string>
#include "base/logging.h"
#include "base/posix/eintr_wrapper.h"
#include "sandbox/linux/seccomp-bpf/syscall.h"
#include "sandbox/linux/services/syscall_wrappers.h"
#include "sandbox/linux/system_headers/linux_signal.h"
namespace sandbox {
void Die::ExitGroup() {
// exit_group() should exit our program. After all, it is defined as a
// function that doesn't return. But things can theoretically go wrong.
// Especially, since we are dealing with system call filters. Continuing
// execution would be very bad in most cases where ExitGroup() gets called.
// So, we'll try a few other strategies too.
Syscall::Call(__NR_exit_group, 1);
// We have no idea what our run-time environment looks like. So, signal
// handlers might or might not do the right thing. Try to reset settings
// to a defined state; but we have not way to verify whether we actually
// succeeded in doing so. Nonetheless, triggering a fatal signal could help
// us terminate.
struct sigaction sa = {};
sa.sa_handler = LINUX_SIG_DFL;
sa.sa_flags = LINUX_SA_RESTART;
sys_sigaction(LINUX_SIGSEGV, &sa, nullptr);
Syscall::Call(__NR_prctl, PR_SET_DUMPABLE, (void*)0, (void*)0, (void*)0);
if (*(volatile char*)0) {
}
// If there is no way for us to ask for the program to exit, the next
// best thing we can do is to loop indefinitely. Maybe, somebody will notice
// and file a bug...
// We in fact retry the system call inside of our loop so that it will
// stand out when somebody tries to diagnose the problem by using "strace".
for (;;) {
Syscall::Call(__NR_exit_group, 1);
}
}
void Die::SandboxDie(const char* msg, const char* file, int line) {
if (simple_exit_) {
LogToStderr(msg, file, line);
} else {
logging::LogMessage(file, line, logging::LOG_FATAL).stream() << msg;
}
ExitGroup();
}
void Die::RawSandboxDie(const char* msg) {
if (!msg)
msg = "";
RAW_LOG(FATAL, msg);
ExitGroup();
}
void Die::SandboxInfo(const char* msg, const char* file, int line) {
if (!suppress_info_) {
logging::LogMessage(file, line, logging::LOG_INFO).stream() << msg;
}
}
void Die::LogToStderr(const char* msg, const char* file, int line) {
if (msg) {
char buf[40];
snprintf(buf, sizeof(buf), "%d", line);
std::string s = std::string(file) + ":" + buf + ":" + msg + "\n";
// No need to loop. Short write()s are unlikely and if they happen we
// probably prefer them over a loop that blocks.
ignore_result(
HANDLE_EINTR(Syscall::Call(__NR_write, 2, s.c_str(), s.length())));
}
}
bool Die::simple_exit_ = false;
bool Die::suppress_info_ = false;
} // namespace sandbox
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