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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// Copyright (c) 2008 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 "base/process_util.h"
#include <ctype.h>
#include <fcntl.h>
#include <memory>
#include <unistd.h>
#include <string>
#include <sys/types.h>
#include <sys/wait.h>
#include "base/eintr_wrapper.h"
#include "base/file_util.h"
#include "base/logging.h"
#include "base/string_util.h"
#include "nsLiteralString.h"
#include "mozilla/UniquePtr.h"
#include "prenv.h"
#include "prmem.h"
/*
* On our platforms we use an arbitrary UID.
* This is generally the UID for user `nobody', albeit it is not
* always the case.
*/
# define CHILD_UNPRIVILEGED_UID 65534
# define CHILD_UNPRIVILEGED_GID 65534
namespace {
static mozilla::EnvironmentLog gProcessLog("MOZ_PROCESS_LOG");
} // namespace
namespace base {
class EnvironmentEnvp
{
public:
EnvironmentEnvp()
: mEnvp(PR_DuplicateEnvironment()) {}
explicit EnvironmentEnvp(const environment_map &em)
{
mEnvp = (char **)PR_Malloc(sizeof(char *) * (em.size() + 1));
if (!mEnvp) {
return;
}
char **e = mEnvp;
for (environment_map::const_iterator it = em.begin();
it != em.end(); ++it, ++e) {
std::string str = it->first;
str += "=";
str += it->second;
size_t len = str.length() + 1;
*e = static_cast<char*>(PR_Malloc(len));
memcpy(*e, str.c_str(), len);
}
*e = NULL;
}
~EnvironmentEnvp()
{
if (!mEnvp) {
return;
}
for (char **e = mEnvp; *e; ++e) {
PR_Free(*e);
}
PR_Free(mEnvp);
}
char * const *AsEnvp() { return mEnvp; }
void ToMap(environment_map &em)
{
if (!mEnvp) {
return;
}
em.clear();
for (char **e = mEnvp; *e; ++e) {
const char *eq;
if ((eq = strchr(*e, '=')) != NULL) {
std::string varname(*e, eq - *e);
em[varname.c_str()] = &eq[1];
}
}
}
private:
char **mEnvp;
};
class Environment : public environment_map
{
public:
Environment()
{
EnvironmentEnvp envp;
envp.ToMap(*this);
}
char * const *AsEnvp() {
mEnvp.reset(new EnvironmentEnvp(*this));
return mEnvp->AsEnvp();
}
void Merge(const environment_map &em)
{
for (const_iterator it = em.begin(); it != em.end(); ++it) {
(*this)[it->first] = it->second;
}
}
private:
std::auto_ptr<EnvironmentEnvp> mEnvp;
};
bool LaunchApp(const std::vector<std::string>& argv,
const file_handle_mapping_vector& fds_to_remap,
bool wait, ProcessHandle* process_handle) {
return LaunchApp(argv, fds_to_remap, environment_map(),
wait, process_handle);
}
bool LaunchApp(const std::vector<std::string>& argv,
const file_handle_mapping_vector& fds_to_remap,
const environment_map& env_vars_to_set,
bool wait, ProcessHandle* process_handle,
ProcessArchitecture arch) {
return LaunchApp(argv, fds_to_remap, env_vars_to_set,
PRIVILEGES_INHERIT,
wait, process_handle);
}
bool LaunchApp(const std::vector<std::string>& argv,
const file_handle_mapping_vector& fds_to_remap,
const environment_map& env_vars_to_set,
ChildPrivileges privs,
bool wait, ProcessHandle* process_handle,
ProcessArchitecture arch) {
mozilla::UniquePtr<char*[]> argv_cstr(new char*[argv.size() + 1]);
// Illegal to allocate memory after fork and before execvp
InjectiveMultimap fd_shuffle1, fd_shuffle2;
fd_shuffle1.reserve(fds_to_remap.size());
fd_shuffle2.reserve(fds_to_remap.size());
Environment env;
env.Merge(env_vars_to_set);
char * const *envp = env.AsEnvp();
if (!envp) {
DLOG(ERROR) << "FAILED to duplicate environment for: " << argv_cstr[0];
return false;
}
pid_t pid = fork();
if (pid < 0)
return false;
if (pid == 0) {
for (file_handle_mapping_vector::const_iterator
it = fds_to_remap.begin(); it != fds_to_remap.end(); ++it) {
fd_shuffle1.push_back(InjectionArc(it->first, it->second, false));
fd_shuffle2.push_back(InjectionArc(it->first, it->second, false));
}
if (!ShuffleFileDescriptors(&fd_shuffle1))
_exit(127);
CloseSuperfluousFds(fd_shuffle2);
for (size_t i = 0; i < argv.size(); i++)
argv_cstr[i] = const_cast<char*>(argv[i].c_str());
argv_cstr[argv.size()] = NULL;
SetCurrentProcessPrivileges(privs);
execve(argv_cstr[0], argv_cstr.get(), envp);
// if we get here, we're in serious trouble and should complain loudly
// NOTE: This is async signal unsafe; it could deadlock instead. (But
// only on debug builds; otherwise it's a signal-safe no-op.)
DLOG(ERROR) << "FAILED TO exec() CHILD PROCESS, path: " << argv_cstr[0];
_exit(127);
} else {
gProcessLog.print("==> process %d launched child process %d\n",
GetCurrentProcId(), pid);
if (wait)
HANDLE_EINTR(waitpid(pid, 0, 0));
if (process_handle)
*process_handle = pid;
}
return true;
}
bool LaunchApp(const CommandLine& cl,
bool wait, bool start_hidden,
ProcessHandle* process_handle) {
file_handle_mapping_vector no_files;
return LaunchApp(cl.argv(), no_files, wait, process_handle);
}
void SetCurrentProcessPrivileges(ChildPrivileges privs) {
if (privs == PRIVILEGES_INHERIT) {
return;
}
gid_t gid = CHILD_UNPRIVILEGED_GID;
uid_t uid = CHILD_UNPRIVILEGED_UID;
if (setgid(gid) != 0) {
DLOG(ERROR) << "FAILED TO setgid() CHILD PROCESS";
_exit(127);
}
if (setuid(uid) != 0) {
DLOG(ERROR) << "FAILED TO setuid() CHILD PROCESS";
_exit(127);
}
if (chdir("/") != 0)
gProcessLog.print("==> could not chdir()\n");
}
} // namespace base
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