die.cc revision a3f6a49ab37290eeeb8db0f41ec0f1cb74a68be7 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include <errno.h>
6#include <linux/unistd.h>
7#include <stdio.h>
8#include <sys/prctl.h>
9
10#include <string>
11
12#include "base/logging.h"
13#include "base/posix/eintr_wrapper.h"
14#include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
15#include "sandbox/linux/seccomp-bpf/syscall.h"
16
17namespace sandbox {
18
19void Die::ExitGroup() {
20  // exit_group() should exit our program. After all, it is defined as a
21  // function that doesn't return. But things can theoretically go wrong.
22  // Especially, since we are dealing with system call filters. Continuing
23  // execution would be very bad in most cases where ExitGroup() gets called.
24  // So, we'll try a few other strategies too.
25  SandboxSyscall(__NR_exit_group, 1);
26
27  // We have no idea what our run-time environment looks like. So, signal
28  // handlers might or might not do the right thing. Try to reset settings
29  // to a defined state; but we have not way to verify whether we actually
30  // succeeded in doing so. Nonetheless, triggering a fatal signal could help
31  // us terminate.
32  signal(SIGSEGV, SIG_DFL);
33  SandboxSyscall(__NR_prctl, PR_SET_DUMPABLE, (void*)0, (void*)0, (void*)0);
34  if (*(volatile char*)0) {
35  }
36
37  // If there is no way for us to ask for the program to exit, the next
38  // best thing we can do is to loop indefinitely. Maybe, somebody will notice
39  // and file a bug...
40  // We in fact retry the system call inside of our loop so that it will
41  // stand out when somebody tries to diagnose the problem by using "strace".
42  for (;;) {
43    SandboxSyscall(__NR_exit_group, 1);
44  }
45}
46
47void Die::SandboxDie(const char* msg, const char* file, int line) {
48  if (simple_exit_) {
49    LogToStderr(msg, file, line);
50  } else {
51    logging::LogMessage(file, line, logging::LOG_FATAL).stream() << msg;
52  }
53  ExitGroup();
54}
55
56void Die::RawSandboxDie(const char* msg) {
57  if (!msg)
58    msg = "";
59  RAW_LOG(FATAL, msg);
60  ExitGroup();
61}
62
63void Die::SandboxInfo(const char* msg, const char* file, int line) {
64  if (!suppress_info_) {
65    logging::LogMessage(file, line, logging::LOG_INFO).stream() << msg;
66  }
67}
68
69void Die::LogToStderr(const char* msg, const char* file, int line) {
70  if (msg) {
71    char buf[40];
72    snprintf(buf, sizeof(buf), "%d", line);
73    std::string s = std::string(file) + ":" + buf + ":" + msg + "\n";
74
75    // No need to loop. Short write()s are unlikely and if they happen we
76    // probably prefer them over a loop that blocks.
77    ignore_result(
78        HANDLE_EINTR(SandboxSyscall(__NR_write, 2, s.c_str(), s.length())));
79  }
80}
81
82bool Die::simple_exit_ = false;
83bool Die::suppress_info_ = false;
84
85}  // namespace sandbox
86