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
17 namespace sandbox {
18
ExitGroup()19 void 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 Syscall::Call(__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 Syscall::Call(__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 Syscall::Call(__NR_exit_group, 1);
44 }
45 }
46
SandboxDie(const char * msg,const char * file,int line)47 void 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
RawSandboxDie(const char * msg)56 void Die::RawSandboxDie(const char* msg) {
57 if (!msg)
58 msg = "";
59 RAW_LOG(FATAL, msg);
60 ExitGroup();
61 }
62
SandboxInfo(const char * msg,const char * file,int line)63 void 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
LogToStderr(const char * msg,const char * file,int line)69 void 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(Syscall::Call(__NR_write, 2, s.c_str(), s.length())));
79 }
80 }
81
82 bool Die::simple_exit_ = false;
83 bool Die::suppress_info_ = false;
84
85 } // namespace sandbox
86