Add an API around zygoteHost so that chrome doesn't reach into the internal content implementation.

content/browser/zygote_host_linux.cc

Index: content/browser/zygote_host_linux.cc
===================================================================
--- content/browser/zygote_host_linux.cc	(revision 123506)
+++ content/browser/zygote_host_linux.cc	(working copy)
@@ -1,445 +0,0 @@
-// Copyright (c) 2012 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 "content/browser/zygote_host_linux.h"
-
-#include <sys/socket.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <unistd.h>
-
-#include "base/base_switches.h"
-#include "base/command_line.h"
-#include "base/eintr_wrapper.h"
-#include "base/environment.h"
-#include "base/file_util.h"
-#include "base/linux_util.h"
-#include "base/logging.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/metrics/histogram.h"
-#include "base/path_service.h"
-#include "base/pickle.h"
-#include "base/process_util.h"
-#include "base/string_number_conversions.h"
-#include "base/string_util.h"
-#include "base/time.h"
-#include "base/utf_string_conversions.h"
-#include "content/browser/renderer_host/render_sandbox_host_linux.h"
-#include "content/common/unix_domain_socket_posix.h"
-#include "content/public/browser/content_browser_client.h"
-#include "content/public/common/content_switches.h"
-#include "content/public/common/result_codes.h"
-#include "sandbox/linux/suid/suid_unsafe_environment_variables.h"
-
-#if defined(USE_TCMALLOC)
-#include "third_party/tcmalloc/chromium/src/google/heap-profiler.h"
-#endif
-
-static void SaveSUIDUnsafeEnvironmentVariables() {
-  // The ELF loader will clear many environment variables so we save them to
-  // different names here so that the SUID sandbox can resolve them for the
-  // renderer.
-
-  for (unsigned i = 0; kSUIDUnsafeEnvironmentVariables[i]; ++i) {
-    const char* const envvar = kSUIDUnsafeEnvironmentVariables[i];
-    char* const saved_envvar = SandboxSavedEnvironmentVariable(envvar);
-    if (!saved_envvar)
-      continue;
-
-    scoped_ptr<base::Environment> env(base::Environment::Create());
-    std::string value;
-    if (env->GetVar(envvar, &value))
-      env->SetVar(saved_envvar, value);
-    else
-      env->UnSetVar(saved_envvar);
-
-    free(saved_envvar);
-  }
-}
-
-ZygoteHost::ZygoteHost()
-    : control_fd_(-1),
-      pid_(-1),
-      init_(false),
-      using_suid_sandbox_(false),
-      have_read_sandbox_status_word_(false),
-      sandbox_status_(0) {}
-
-ZygoteHost::~ZygoteHost() {
-  if (init_)
-    close(control_fd_);
-}
-
-// static
-ZygoteHost* ZygoteHost::GetInstance() {
-  return Singleton<ZygoteHost>::get();
-}
-
-void ZygoteHost::Init(const std::string& sandbox_cmd) {
-  DCHECK(!init_);
-  init_ = true;
-
-  FilePath chrome_path;
-  CHECK(PathService::Get(base::FILE_EXE, &chrome_path));
-  CommandLine cmd_line(chrome_path);
-
-  cmd_line.AppendSwitchASCII(switches::kProcessType, switches::kZygoteProcess);
-
-  int fds[2];
-#if defined(OS_FREEBSD) || defined(OS_OPENBSD)
-  // The BSDs often don't support SOCK_SEQPACKET yet, so fall back to
-  // SOCK_DGRAM if necessary.
-  if (socketpair(PF_UNIX, SOCK_SEQPACKET, 0, fds) != 0)
-    CHECK(socketpair(PF_UNIX, SOCK_DGRAM, 0, fds) == 0);
-#else
-  CHECK(socketpair(PF_UNIX, SOCK_SEQPACKET, 0, fds) == 0);
-#endif
-  base::FileHandleMappingVector 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)) {
-    cmd_line.PrependWrapper(
-        browser_command_line.GetSwitchValueNative(switches::kZygoteCmdPrefix));
-  }
-  // Append any switches from the browser process that need to be forwarded on
-  // to the zygote/renderers.
-  // Should this list be obtained from browser_render_process_host.cc?
-  static const char* kForwardSwitches[] = {
-    switches::kAllowSandboxDebugging,
-    switches::kLoggingLevel,
-    switches::kEnableLogging,  // Support, e.g., --enable-logging=stderr.
-    switches::kV,
-    switches::kVModule,
-    switches::kRegisterPepperPlugins,
-    switches::kDisableSeccompSandbox,
-    switches::kEnableSeccompSandbox,
-  };
-  cmd_line.CopySwitchesFrom(browser_command_line, kForwardSwitches,
-                            arraysize(kForwardSwitches));
-
-  content::GetContentClient()->browser()->AppendExtraCommandLineSwitches(
-      &cmd_line, -1);
-
-  sandbox_binary_ = sandbox_cmd.c_str();
-
-  if (!sandbox_cmd.empty()) {
-    struct stat st;
-    if (stat(sandbox_binary_.c_str(), &st) != 0) {
-      LOG(FATAL) << "The SUID sandbox helper binary is missing: "
-                 << sandbox_binary_ << " Aborting now.";
-    }
-
-    if (access(sandbox_binary_.c_str(), X_OK) == 0 &&
-        (st.st_uid == 0) &&
-        (st.st_mode & S_ISUID) &&
-        (st.st_mode & S_IXOTH)) {
-      using_suid_sandbox_ = true;
-      cmd_line.PrependWrapper(sandbox_binary_);
-
-      SaveSUIDUnsafeEnvironmentVariables();
-    } 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 "
-                 << sandbox_binary_ << " is owned by root and has mode 4755.";
-    }
-  } else {
-    LOG(WARNING) << "Running without the SUID sandbox! See "
-        "http://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment "
-        "for more information on developing with the sandbox on.";
-  }
-
-  // Start up the sandbox host process and get the file descriptor for the
-  // renderers to talk to it.
-  const int sfd = RenderSandboxHostLinux::GetInstance()->GetRendererSocket();
-  fds_to_map.push_back(std::make_pair(sfd, 5));
-
-  int dummy_fd = -1;
-  if (using_suid_sandbox_) {
-    dummy_fd = socket(PF_UNIX, SOCK_DGRAM, 0);
-    CHECK(dummy_fd >= 0);
-    fds_to_map.push_back(std::make_pair(dummy_fd, 7));
-  }
-
-  base::ProcessHandle process = -1;
-  base::LaunchOptions options;
-  options.fds_to_remap = &fds_to_map;
-  base::LaunchProcess(cmd_line.argv(), options, &process);
-  CHECK(process != -1) << "Failed to launch zygote process";
-
-  if (using_suid_sandbox_) {
-    // In the SUID sandbox, the real zygote is forked from the sandbox.
-    // We need to look for it.
-    // But first, wait for the zygote to tell us it's running.
-    // The sending code is in content/browser/zygote_main_linux.cc.
-    std::vector<int> fds_vec;
-    const int kExpectedLength = sizeof(kZygoteMagic);
-    char buf[kExpectedLength];
-    const ssize_t len = UnixDomainSocket::RecvMsg(fds[0], buf, sizeof(buf),
-                                                  &fds_vec);
-    CHECK(len == kExpectedLength) << "Incorrect zygote magic length";
-    CHECK(0 == strcmp(buf, kZygoteMagic)) << "Incorrect zygote magic";
-
-    std::string inode_output;
-    ino_t inode = 0;
-    // Figure out the inode for |dummy_fd|, close |dummy_fd| on our end,
-    // and find the zygote process holding |dummy_fd|.
-    if (base::FileDescriptorGetInode(&inode, dummy_fd)) {
-      close(dummy_fd);
-      std::vector<std::string> get_inode_cmdline;
-      get_inode_cmdline.push_back(sandbox_binary_);
-      get_inode_cmdline.push_back(base::kFindInodeSwitch);
-      get_inode_cmdline.push_back(base::Int64ToString(inode));
-      CommandLine get_inode_cmd(get_inode_cmdline);
-      if (base::GetAppOutput(get_inode_cmd, &inode_output)) {
-        base::StringToInt(inode_output, &pid_);
-      }
-    }
-    CHECK(pid_ > 0) << "Did not find zygote process (using sandbox binary "
-        << sandbox_binary_ << ")";
-
-    if (process != pid_) {
-      // Reap the sandbox.
-      base::EnsureProcessGetsReaped(process);
-    }
-  } else {
-    // Not using the SUID sandbox.
-    pid_ = process;
-  }
-
-  close(fds[1]);
-  control_fd_ = fds[0];
-
-  Pickle pickle;
-  pickle.WriteInt(kCmdGetSandboxStatus);
-  std::vector<int> empty_fds;
-  if (!UnixDomainSocket::SendMsg(control_fd_, pickle.data(), pickle.size(),
-                                 empty_fds))
-    LOG(FATAL) << "Cannot communicate with zygote";
-  // We don't wait for the reply. We'll read it in ReadReply.
-}
-
-ssize_t ZygoteHost::ReadReply(void* buf, size_t buf_len) {
-  // At startup we send a kCmdGetSandboxStatus request to the zygote, but don't
-  // wait for the reply. Thus, the first time that we read from the zygote, we
-  // get the reply to that request.
-  if (!have_read_sandbox_status_word_) {
-    if (HANDLE_EINTR(read(control_fd_, &sandbox_status_,
-                          sizeof(sandbox_status_))) !=
-        sizeof(sandbox_status_)) {
-      return -1;
-    }
-    have_read_sandbox_status_word_ = true;
-  }
-
-  return HANDLE_EINTR(read(control_fd_, buf, buf_len));
-}
-
-pid_t ZygoteHost::ForkRequest(
-    const std::vector<std::string>& argv,
-    const base::GlobalDescriptors::Mapping& mapping,
-    const std::string& process_type) {
-  DCHECK(init_);
-  Pickle pickle;
-
-  pickle.WriteInt(kCmdFork);
-  pickle.WriteString(process_type);
-  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);
-  }
-
-  pid_t pid;
-  {
-    base::AutoLock lock(control_lock_);
-    if (!UnixDomainSocket::SendMsg(control_fd_, pickle.data(), pickle.size(),
-                                   fds))
-      return base::kNullProcessHandle;
-
-    // Read the reply, which pickles the PID and an optional UMA enumeration.
-    static const unsigned kMaxReplyLength = 2048;
-    char buf[kMaxReplyLength];
-    const ssize_t len = ReadReply(buf, sizeof(buf));
-
-    Pickle reply_pickle(buf, len);
-    void* iter = NULL;
-    if (len <= 0 || !reply_pickle.ReadInt(&iter, &pid))
-      return base::kNullProcessHandle;
-
-    // If there is a nonempty UMA name string, then there is a UMA
-    // enumeration to record.
-    std::string uma_name;
-    int uma_sample;
-    int uma_boundary_value;
-    if (reply_pickle.ReadString(&iter, &uma_name) &&
-        !uma_name.empty() &&
-        reply_pickle.ReadInt(&iter, &uma_sample) &&
-        reply_pickle.ReadInt(&iter, &uma_boundary_value)) {
-      // We cannot use the UMA_HISTOGRAM_ENUMERATION macro here,
-      // because that's only for when the name is the same every time.
-      // Here we're using whatever name we got from the other side.
-      // But since it's likely that the same one will be used repeatedly
-      // (even though it's not guaranteed), we cache it here.
-      static base::Histogram* uma_histogram;
-      if (!uma_histogram || uma_histogram->histogram_name() != uma_name) {
-        uma_histogram = base::LinearHistogram::FactoryGet(
-            uma_name, 1,
-            uma_boundary_value,
-            uma_boundary_value + 1, base::Histogram::kUmaTargetedHistogramFlag);
-      }
-      uma_histogram->Add(uma_sample);
-    }
-
-    if (pid <= 0)
-      return base::kNullProcessHandle;
-  }
-
-#if !defined(OS_OPENBSD)
-  // This is just a starting score for a renderer or extension (the
-  // only types of processes that will be started this way).  It will
-  // get adjusted as time goes on.  (This is the same value as
-  // chrome::kLowestRendererOomScore in chrome/chrome_constants.h, but
-  // that's not something we can include here.)
-  const int kLowestRendererOomScore = 300;
-  AdjustRendererOOMScore(pid, kLowestRendererOomScore);
-#endif
-
-  return pid;
-}
-
-#if !defined(OS_OPENBSD)
-void ZygoteHost::AdjustRendererOOMScore(base::ProcessHandle pid, int score) {
-  // 1) You can't change the oom_score_adj of a non-dumpable process
-  //    (EPERM) unless you're root. Because of this, we can't set the
-  //    oom_adj from the browser process.
-  //
-  // 2) We can't set the oom_score_adj before entering the sandbox
-  //    because the zygote is in the sandbox and the zygote is as
-  //    critical as the browser process. Its oom_adj value shouldn't
-  //    be changed.
-  //
-  // 3) A non-dumpable process can't even change its own oom_score_adj
-  //    because it's root owned 0644. The sandboxed processes don't
-  //    even have /proc, but one could imagine passing in a descriptor
-  //    from outside.
-  //
-  // So, in the normal case, we use the SUID binary to change it for us.
-  // However, Fedora (and other SELinux systems) don't like us touching other
-  // process's oom_score_adj (or oom_adj) values
-  // (https://bugzilla.redhat.com/show_bug.cgi?id=581256).
-  //
-  // The offical way to get the SELinux mode is selinux_getenforcemode, but I
-  // don't want to add another library to the build as it's sure to cause
-  // problems with other, non-SELinux distros.
-  //
-  // So we just check for files in /selinux. This isn't foolproof, but it's not
-  // bad and it's easy.
-
-  static bool selinux;
-  static bool selinux_valid = false;
-
-  if (!selinux_valid) {
-    const FilePath kSelinuxPath("/selinux");
-    selinux = access(kSelinuxPath.value().c_str(), X_OK) == 0 &&
-        file_util::CountFilesCreatedAfter(kSelinuxPath,
-                                          base::Time::UnixEpoch()) > 0;
-    selinux_valid = true;
-  }
-
-  if (using_suid_sandbox_ && !selinux) {
-#if defined(USE_TCMALLOC)
-    // If heap profiling is running, these processes are not exiting, at least
-    // on ChromeOS. The easiest thing to do is not launch them when profiling.
-    // TODO(stevenjb): Investigate further and fix.
-    if (IsHeapProfilerRunning())
-      return;
-#endif
-    // The command line switch used for supplying the OOM adjustment score
-    // to the setuid sandbox.
-    static const char kAdjustOOMScoreSwitch[] = "--adjust-oom-score";
-
-    std::vector<std::string> adj_oom_score_cmdline;
-    adj_oom_score_cmdline.push_back(sandbox_binary_);
-    adj_oom_score_cmdline.push_back(kAdjustOOMScoreSwitch);
-    adj_oom_score_cmdline.push_back(base::Int64ToString(pid));
-    adj_oom_score_cmdline.push_back(base::IntToString(score));
-
-    base::ProcessHandle sandbox_helper_process;
-    if (base::LaunchProcess(adj_oom_score_cmdline, base::LaunchOptions(),
-                            &sandbox_helper_process)) {
-      base::EnsureProcessGetsReaped(sandbox_helper_process);
-    }
-  } else if (!using_suid_sandbox_) {
-    if (!base::AdjustOOMScore(pid, score))
-      PLOG(ERROR) << "Failed to adjust OOM score of renderer with pid " << pid;
-  }
-}
-#endif
-
-void ZygoteHost::EnsureProcessTerminated(pid_t process) {
-  DCHECK(init_);
-  Pickle pickle;
-
-  pickle.WriteInt(kCmdReap);
-  pickle.WriteInt(process);
-
-  if (HANDLE_EINTR(write(control_fd_, pickle.data(), pickle.size())) < 0)
-    PLOG(ERROR) << "write";
-}
-
-base::TerminationStatus ZygoteHost::GetTerminationStatus(
-    base::ProcessHandle handle,
-    int* exit_code) {
-  DCHECK(init_);
-  Pickle pickle;
-  pickle.WriteInt(kCmdGetTerminationStatus);
-  pickle.WriteInt(handle);
-
-  // Set this now to handle the early termination cases.
-  if (exit_code)
-    *exit_code = content::RESULT_CODE_NORMAL_EXIT;
-
-  static const unsigned kMaxMessageLength = 128;
-  char buf[kMaxMessageLength];
-  ssize_t len;
-  {
-    base::AutoLock lock(control_lock_);
-    if (HANDLE_EINTR(write(control_fd_, pickle.data(), pickle.size())) < 0)
-      PLOG(ERROR) << "write";
-
-    len = ReadReply(buf, sizeof(buf));
-  }
-
-  if (len == -1) {
-    LOG(WARNING) << "Error reading message from zygote: " << errno;
-    return base::TERMINATION_STATUS_NORMAL_TERMINATION;
-  } else if (len == 0) {
-    LOG(WARNING) << "Socket closed prematurely.";
-    return base::TERMINATION_STATUS_NORMAL_TERMINATION;
-  }
-
-  Pickle read_pickle(buf, len);
-  int status, tmp_exit_code;
-  void* iter = NULL;
-  if (!read_pickle.ReadInt(&iter, &status) ||
-      !read_pickle.ReadInt(&iter, &tmp_exit_code)) {
-    LOG(WARNING) << "Error parsing GetTerminationStatus response from zygote.";
-    return base::TERMINATION_STATUS_NORMAL_TERMINATION;
-  }
-
-  if (exit_code)
-    *exit_code = tmp_exit_code;
-
-  return static_cast<base::TerminationStatus>(status);
-}