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// 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"
#include "sandbox/linux/suid/suid_unsafe_environment_variables.h"
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;
const char* const value = getenv(envvar);
if (value)
setenv(saved_envvar, value, 1 /* overwrite */);
else
unsetenv(saved_envvar);
free(saved_envvar);
}
}
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);
}
// 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?
if (browser_command_line.HasSwitch(switches::kAllowSandboxDebugging)) {
cmd_line.AppendSwitch(switches::kAllowSandboxDebugging);
}
if (browser_command_line.HasSwitch(switches::kLoggingLevel)) {
cmd_line.AppendSwitchWithValue(switches::kLoggingLevel,
browser_command_line.GetSwitchValue(
switches::kLoggingLevel));
}
if (browser_command_line.HasSwitch(switches::kEnableLogging)) {
// Append with value to support --enable-logging=stderr.
cmd_line.AppendSwitchWithValue(switches::kEnableLogging,
browser_command_line.GetSwitchValue(
switches::kEnableLogging));
}
const char* sandbox_binary = NULL;
struct stat st;
// In Chromium branded builds, developers can set an environment variable to
// use the development sandbox. See
// http://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment
if (stat("/proc/self/exe", &st) == 0 &&
st.st_uid == getuid()) {
sandbox_binary = getenv("CHROME_DEVEL_SANDBOX");
}
#if defined(LINUX_SANDBOX_PATH)
if (!sandbox_binary)
sandbox_binary = LINUX_SANDBOX_PATH;
#endif
if (sandbox_binary && stat(sandbox_binary, &st) == 0) {
if (access(sandbox_binary, X_OK) == 0 &&
(st.st_mode & S_ISUID) &&
(st.st_mode & S_IXOTH)) {
cmd_line.PrependWrapper(ASCIIToWide(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 mode 4755.";
}
}
// 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";
pid_ = 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;
}
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