chrome/browser/zygote_host_linux.cc

// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/zygote_host_linux.h"

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>

#include "base/command_line.h"
#include "base/eintr_wrapper.h"
#include "base/logging.h"
#include "base/path_service.h"
#include "base/pickle.h"
#include "base/process_util.h"
#include "base/string_util.h"
#include "base/unix_domain_socket_posix.h"

#include "chrome/browser/renderer_host/render_sandbox_host_linux.h"
#include "chrome/common/chrome_constants.h"
#include "chrome/common/chrome_switches.h"

// Previously we just looked for the binary next to the Chromium binary. But
// this breaks people who do a build-all.
// NOTE packagers: change this.
static const char kSandboxBinary[] = "/opt/google/chrome/chrome-sandbox";

ZygoteHost::ZygoteHost() {
  std::wstring chrome_path;
  CHECK(PathService::Get(base::FILE_EXE, &chrome_path));
  CommandLine cmd_line(chrome_path);

  cmd_line.AppendSwitchWithValue(switches::kProcessType,
                                 switches::kZygoteProcess);

  int fds[2];
  CHECK(socketpair(PF_UNIX, SOCK_SEQPACKET, 0, fds) == 0);
  base::file_handle_mapping_vector fds_to_map;
  fds_to_map.push_back(std::make_pair(fds[1], 3));

  const CommandLine& browser_command_line = *CommandLine::ForCurrentProcess();
  if (browser_command_line.HasSwitch(switches::kZygoteCmdPrefix)) {
    const std::wstring prefix =
        browser_command_line.GetSwitchValue(switches::kZygoteCmdPrefix);
    cmd_line.PrependWrapper(prefix);
  }

  const std::string kSandboxPath =
    WideToASCII(std::wstring(L"/var/run/") +
                chrome::kBrowserProcessExecutableName +
                L"-sandbox");

  struct stat st;
  if (stat(kSandboxBinary, &st) == 0) {
    if (access(kSandboxBinary, X_OK) == 0 &&
        (st.st_mode & S_ISUID) &&
        (st.st_mode & S_IXOTH) &&
        access(kSandboxPath.c_str(), F_OK) == 0) {
      cmd_line.PrependWrapper(kSandboxBinary);
    } else {
      LOG(FATAL) << "The SUID sandbox helper binary was found, but is not "
                    "configured correctly. Rather than run without sandboxing "
                    "I'm aborting now. You need to make sure that "
                 << kSandboxBinary << " is mode 4755 and that "
                 << kSandboxPath << " exists";
    }
  }

  // Start up the sandbox host process and get the file descriptor for the
  // renderers to talk to it.
  const int sfd = Singleton<RenderSandboxHostLinux>()->GetRendererSocket();
  fds_to_map.push_back(std::make_pair(sfd, 5));

  base::ProcessHandle process;
  base::LaunchApp(cmd_line.argv(), fds_to_map, false, &process);
  CHECK(process != -1) << "Failed to launch zygote process";

  close(fds[1]);
  control_fd_ = fds[0];
}

ZygoteHost::~ZygoteHost() {
  close(control_fd_);
}

pid_t ZygoteHost::ForkRenderer(
    const std::vector<std::string>& argv,
    const base::GlobalDescriptors::Mapping& mapping) {
  Pickle pickle;

  pickle.WriteInt(kCmdFork);
  pickle.WriteInt(argv.size());
  for (std::vector<std::string>::const_iterator
       i = argv.begin(); i != argv.end(); ++i)
    pickle.WriteString(*i);

  pickle.WriteInt(mapping.size());

  std::vector<int> fds;
  for (base::GlobalDescriptors::Mapping::const_iterator
       i = mapping.begin(); i != mapping.end(); ++i) {
    pickle.WriteUInt32(i->first);
    fds.push_back(i->second);
  }

  if (!base::SendMsg(control_fd_, pickle.data(), pickle.size(), fds))
    return -1;

  pid_t pid;
  if (HANDLE_EINTR(read(control_fd_, &pid, sizeof(pid))) != sizeof(pid))
    return -1;

  return pid;
}

void ZygoteHost::EnsureProcessTerminated(pid_t process) {
  Pickle pickle;

  pickle.WriteInt(kCmdReap);
  pickle.WriteInt(process);

  HANDLE_EINTR(write(control_fd_, pickle.data(), pickle.size()));
}

bool ZygoteHost::DidProcessCrash(base::ProcessHandle handle,
                                 bool* child_exited) {
  Pickle pickle;
  pickle.WriteInt(kCmdDidProcessCrash);
  pickle.WriteInt(handle);

  HANDLE_EINTR(write(control_fd_, pickle.data(), pickle.size()));

  static const unsigned kMaxMessageLength = 128;
  char buf[kMaxMessageLength];
  const ssize_t len = HANDLE_EINTR(read(control_fd_, buf, sizeof(buf)));

  if (len == -1) {
    LOG(WARNING) << "Error reading message from zygote: " << errno;
    return false;
  } else if (len == 0) {
    LOG(WARNING) << "Socket closed prematurely.";
    return false;
  }

  Pickle read_pickle(buf, len);
  bool did_crash, tmp_child_exited;
  void* iter = NULL;
  if (!read_pickle.ReadBool(&iter, &did_crash) ||
      !read_pickle.ReadBool(&iter, &tmp_child_exited)) {
    LOG(WARNING) << "Error parsing DidProcessCrash response from zygote.";
    return false;
  }

  if (child_exited)
    *child_exited = tmp_child_exited;

  return did_crash;
}