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 "sandbox/linux/seccomp-bpf/die.h"
6
7#include <errno.h>
8#include <signal.h>
9#include <stdio.h>
10#include <sys/prctl.h>
11#include <sys/syscall.h>
12#include <unistd.h>
13
14#include <string>
15
16#include "base/logging.h"
17#include "base/posix/eintr_wrapper.h"
18#include "sandbox/linux/seccomp-bpf/syscall.h"
19
20namespace sandbox {
21
22void Die::ExitGroup() {
23  // exit_group() should exit our program. After all, it is defined as a
24  // function that doesn't return. But things can theoretically go wrong.
25  // Especially, since we are dealing with system call filters. Continuing
26  // execution would be very bad in most cases where ExitGroup() gets called.
27  // So, we'll try a few other strategies too.
28  Syscall::Call(__NR_exit_group, 1);
29
30  // We have no idea what our run-time environment looks like. So, signal
31  // handlers might or might not do the right thing. Try to reset settings
32  // to a defined state; but we have not way to verify whether we actually
33  // succeeded in doing so. Nonetheless, triggering a fatal signal could help
34  // us terminate.
35  signal(SIGSEGV, SIG_DFL);
36  Syscall::Call(__NR_prctl, PR_SET_DUMPABLE, (void*)0, (void*)0, (void*)0);
37  if (*(volatile char*)0) {
38  }
39
40  // If there is no way for us to ask for the program to exit, the next
41  // best thing we can do is to loop indefinitely. Maybe, somebody will notice
42  // and file a bug...
43  // We in fact retry the system call inside of our loop so that it will
44  // stand out when somebody tries to diagnose the problem by using "strace".
45  for (;;) {
46    Syscall::Call(__NR_exit_group, 1);
47  }
48}
49
50void Die::SandboxDie(const char* msg, const char* file, int line) {
51  if (simple_exit_) {
52    LogToStderr(msg, file, line);
53  } else {
54    logging::LogMessage(file, line, logging::LOG_FATAL).stream() << msg;
55  }
56  ExitGroup();
57}
58
59void Die::RawSandboxDie(const char* msg) {
60  if (!msg)
61    msg = "";
62  RAW_LOG(FATAL, msg);
63  ExitGroup();
64}
65
66void Die::SandboxInfo(const char* msg, const char* file, int line) {
67  if (!suppress_info_) {
68    logging::LogMessage(file, line, logging::LOG_INFO).stream() << msg;
69  }
70}
71
72void Die::LogToStderr(const char* msg, const char* file, int line) {
73  if (msg) {
74    char buf[40];
75    snprintf(buf, sizeof(buf), "%d", line);
76    std::string s = std::string(file) + ":" + buf + ":" + msg + "\n";
77
78    // No need to loop. Short write()s are unlikely and if they happen we
79    // probably prefer them over a loop that blocks.
80    ignore_result(
81        HANDLE_EINTR(Syscall::Call(__NR_write, 2, s.c_str(), s.length())));
82  }
83}
84
85bool Die::simple_exit_ = false;
86bool Die::suppress_info_ = false;
87
88}  // namespace sandbox
89