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 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 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 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 56 void Die::RawSandboxDie(const char* msg) { 57 if (!msg) 58 msg = ""; 59 RAW_LOG(FATAL, msg); 60 ExitGroup(); 61 } 62 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 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(SandboxSyscall(__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
