// Copyright (c) 2010 Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <assert.h>
#include <dirent.h>
#include <fcntl.h>
#include <limits.h>
#include <poll.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <vector>
#include "client/linux/crash_generation/crash_generation_server.h"
#include "client/linux/crash_generation/client_info.h"
#include "client/linux/handler/exception_handler.h"
#include "client/linux/minidump_writer/minidump_writer.h"
#include "common/linux/eintr_wrapper.h"
#include "common/linux/guid_creator.h"
#include "common/linux/safe_readlink.h"
static const char kCommandQuit = 'x';
namespace google_breakpad {
CrashGenerationServer::CrashGenerationServer(
const int listen_fd,
OnClientDumpRequestCallback dump_callback,
void* dump_context,
OnClientExitingCallback exit_callback,
void* exit_context,
bool generate_dumps,
const string* dump_path) :
server_fd_(listen_fd),
dump_callback_(dump_callback),
dump_context_(dump_context),
exit_callback_(exit_callback),
exit_context_(exit_context),
generate_dumps_(generate_dumps),
started_(false)
{
if (dump_path)
dump_dir_ = *dump_path;
else
dump_dir_ = "/tmp";
}
CrashGenerationServer::~CrashGenerationServer()
{
if (started_)
Stop();
}
bool
CrashGenerationServer::Start()
{
if (started_ || 0 > server_fd_)
return false;
int control_pipe[2];
if (pipe(control_pipe))
return false;
if (fcntl(control_pipe[0], F_SETFD, FD_CLOEXEC))
return false;
if (fcntl(control_pipe[1], F_SETFD, FD_CLOEXEC))
return false;
if (fcntl(control_pipe[0], F_SETFL, O_NONBLOCK))
return false;
control_pipe_in_ = control_pipe[0];
control_pipe_out_ = control_pipe[1];
if (pthread_create(&thread_, NULL,
ThreadMain, reinterpret_cast<void*>(this)))
return false;
started_ = true;
return true;
}
void
CrashGenerationServer::Stop()
{
assert(pthread_self() != thread_);
if (!started_)
return;
HANDLE_EINTR(write(control_pipe_out_, &kCommandQuit, 1));
void* dummy;
pthread_join(thread_, &dummy);
started_ = false;
}
//static
bool
CrashGenerationServer::CreateReportChannel(int* server_fd, int* client_fd)
{
int fds[2];
if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, fds))
return false;
static const int on = 1;
// Enable passcred on the server end of the socket
if (setsockopt(fds[1], SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)))
return false;
if (fcntl(fds[1], F_SETFL, O_NONBLOCK))
return false;
if (fcntl(fds[1], F_SETFD, FD_CLOEXEC))
return false;
*client_fd = fds[0];
*server_fd = fds[1];
return true;
}
// The following methods/functions execute on the server thread
void
CrashGenerationServer::Run()
{
struct pollfd pollfds[2];
memset(&pollfds, 0, sizeof(pollfds));
pollfds[0].fd = server_fd_;
pollfds[0].events = POLLIN;
pollfds[1].fd = control_pipe_in_;
pollfds[1].events = POLLIN;
while (true) {
// infinite timeout
int nevents = poll(pollfds, sizeof(pollfds)/sizeof(pollfds[0]), -1);
if (-1 == nevents) {
if (EINTR == errno) {
continue;
} else {
return;
}
}
if (pollfds[0].revents && !ClientEvent(pollfds[0].revents))
return;
if (pollfds[1].revents && !ControlEvent(pollfds[1].revents))
return;
}
}
bool
CrashGenerationServer::ClientEvent(short revents)
{
if (POLLHUP & revents)
return false;
assert(POLLIN & revents);
// A process has crashed and has signaled us by writing a datagram
// to the death signal socket. The datagram contains the crash context needed
// for writing the minidump as well as a file descriptor and a credentials
// block so that they can't lie about their pid.
// The length of the control message:
static const unsigned kControlMsgSize =
CMSG_SPACE(sizeof(int)) + CMSG_SPACE(sizeof(struct ucred));
// The length of the regular payload:
static const unsigned kCrashContextSize =
sizeof(google_breakpad::ExceptionHandler::CrashContext);
struct msghdr msg = {0};
struct iovec iov[1];
char crash_context[kCrashContextSize];
char control[kControlMsgSize];
const ssize_t expected_msg_size = sizeof(crash_context);
iov[0].iov_base = crash_context;
iov[0].iov_len = sizeof(crash_context);
msg.msg_iov = iov;
msg.msg_iovlen = sizeof(iov)/sizeof(iov[0]);
msg.msg_control = control;
msg.msg_controllen = kControlMsgSize;
const ssize_t msg_size = HANDLE_EINTR(recvmsg(server_fd_, &msg, 0));
if (msg_size != expected_msg_size)
return true;
if (msg.msg_controllen != kControlMsgSize ||
msg.msg_flags & ~MSG_TRUNC)
return true;
// Walk the control payload and extract the file descriptor and validated pid.
pid_t crashing_pid = -1;
int signal_fd = -1;
for (struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg); hdr;
hdr = CMSG_NXTHDR(&msg, hdr)) {
if (hdr->cmsg_level != SOL_SOCKET)
continue;
if (hdr->cmsg_type == SCM_RIGHTS) {
const unsigned len = hdr->cmsg_len -
(((uint8_t*)CMSG_DATA(hdr)) - (uint8_t*)hdr);
assert(len % sizeof(int) == 0u);
const unsigned num_fds = len / sizeof(int);
if (num_fds > 1 || num_fds == 0) {
// A nasty process could try and send us too many descriptors and
// force a leak.
for (unsigned i = 0; i < num_fds; ++i)
close(reinterpret_cast<int*>(CMSG_DATA(hdr))[i]);
return true;
} else {
signal_fd = reinterpret_cast<int*>(CMSG_DATA(hdr))[0];
}
} else if (hdr->cmsg_type == SCM_CREDENTIALS) {
const struct ucred *cred =
reinterpret_cast<struct ucred*>(CMSG_DATA(hdr));
crashing_pid = cred->pid;
}
}
if (crashing_pid == -1 || signal_fd == -1) {
if (signal_fd)
close(signal_fd);
return true;
}
string minidump_filename;
if (!MakeMinidumpFilename(minidump_filename))
return true;
if (!google_breakpad::WriteMinidump(minidump_filename.c_str(),
crashing_pid, crash_context,
kCrashContextSize)) {
close(signal_fd);
return true;
}
if (dump_callback_) {
ClientInfo info(crashing_pid, this);
dump_callback_(dump_context_, &info, &minidump_filename);
}
// Send the done signal to the process: it can exit now.
// (Closing this will make the child's sys_read unblock and return 0.)
close(signal_fd);
return true;
}
bool
CrashGenerationServer::ControlEvent(short revents)
{
if (POLLHUP & revents)
return false;
assert(POLLIN & revents);
char command;
if (read(control_pipe_in_, &command, 1))
return false;
switch (command) {
case kCommandQuit:
return false;
default:
assert(0);
}
return true;
}
bool
CrashGenerationServer::MakeMinidumpFilename(string& outFilename)
{
GUID guid;
char guidString[kGUIDStringLength+1];
if (!(CreateGUID(&guid)
&& GUIDToString(&guid, guidString, sizeof(guidString))))
return false;
char path[PATH_MAX];
snprintf(path, sizeof(path), "%s/%s.dmp", dump_dir_.c_str(), guidString);
outFilename = path;
return true;
}
// static
void*
CrashGenerationServer::ThreadMain(void *arg)
{
reinterpret_cast<CrashGenerationServer*>(arg)->Run();
return NULL;
}
} // namespace google_breakpad