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// 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 "chrome/browser/nacl_host/pnacl_file_host.h"
#include "base/bind.h"
#include "base/file_util.h"
#include "base/files/file_path.h"
#include "base/memory/ref_counted.h"
#include "base/path_service.h"
#include "base/platform_file.h"
#include "base/utf_string_conversions.h"
#include "chrome/browser/renderer_host/chrome_render_message_filter.h"
#include "chrome/common/chrome_paths.h"
#include "chrome/common/render_messages.h"
#include "content/public/browser/browser_thread.h"
#include "ipc/ipc_platform_file.h"
using content::BrowserThread;
namespace {
// Force a prefix to prevent user from opening "magic" files.
const char* kExpectedFilePrefix = "pnacl_public_";
// Restrict PNaCl file lengths to reduce likelyhood of hitting bugs
// in file name limit error-handling-code-paths, etc.
const size_t kMaxFileLength = 40;
void NotifyRendererOfError(
ChromeRenderMessageFilter* chrome_render_message_filter,
IPC::Message* reply_msg) {
reply_msg->set_reply_error();
chrome_render_message_filter->Send(reply_msg);
}
bool PnaclDoOpenFile(const base::FilePath& file_to_open,
base::PlatformFile* out_file) {
base::PlatformFileError error_code;
*out_file = base::CreatePlatformFile(file_to_open,
base::PLATFORM_FILE_OPEN |
base::PLATFORM_FILE_READ,
NULL,
&error_code);
if (error_code != base::PLATFORM_FILE_OK) {
return false;
}
return true;
}
void DoOpenPnaclFile(
ChromeRenderMessageFilter* chrome_render_message_filter,
const std::string& filename,
IPC::Message* reply_msg) {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
base::FilePath full_filepath;
// Do some validation.
if (!pnacl_file_host::PnaclCanOpenFile(filename, &full_filepath)) {
NotifyRendererOfError(chrome_render_message_filter, reply_msg);
return;
}
base::PlatformFile file_to_open;
if (!PnaclDoOpenFile(full_filepath, &file_to_open)) {
NotifyRendererOfError(chrome_render_message_filter, reply_msg);
return;
}
// Send the reply!
// Do any DuplicateHandle magic that is necessary first.
IPC::PlatformFileForTransit target_desc =
IPC::GetFileHandleForProcess(file_to_open,
chrome_render_message_filter->peer_handle(),
true /* Close source */);
if (target_desc == IPC::InvalidPlatformFileForTransit()) {
NotifyRendererOfError(chrome_render_message_filter, reply_msg);
return;
}
ChromeViewHostMsg_GetReadonlyPnaclFD::WriteReplyParams(
reply_msg, target_desc);
chrome_render_message_filter->Send(reply_msg);
}
void DoCreateTemporaryFile(
ChromeRenderMessageFilter* chrome_render_message_filter,
IPC::Message* reply_msg) {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
base::FilePath file_path;
if (!file_util::CreateTemporaryFile(&file_path)) {
NotifyRendererOfError(chrome_render_message_filter, reply_msg);
return;
}
base::PlatformFileError error;
base::PlatformFile file_handle = base::CreatePlatformFile(
file_path,
base::PLATFORM_FILE_CREATE_ALWAYS | base::PLATFORM_FILE_READ |
base::PLATFORM_FILE_WRITE | base::PLATFORM_FILE_TEMPORARY |
base::PLATFORM_FILE_DELETE_ON_CLOSE,
NULL, &error);
if (error != base::PLATFORM_FILE_OK) {
NotifyRendererOfError(chrome_render_message_filter, reply_msg);
return;
}
// Send the reply!
// Do any DuplicateHandle magic that is necessary first.
IPC::PlatformFileForTransit target_desc =
IPC::GetFileHandleForProcess(file_handle,
chrome_render_message_filter->peer_handle(),
true);
if (target_desc == IPC::InvalidPlatformFileForTransit()) {
NotifyRendererOfError(chrome_render_message_filter, reply_msg);
return;
}
ChromeViewHostMsg_NaClCreateTemporaryFile::WriteReplyParams(
reply_msg, target_desc);
chrome_render_message_filter->Send(reply_msg);
}
} // namespace
namespace pnacl_file_host {
void GetReadonlyPnaclFd(
ChromeRenderMessageFilter* chrome_render_message_filter,
const std::string& filename,
IPC::Message* reply_msg) {
if (!BrowserThread::PostTask(
BrowserThread::FILE, FROM_HERE,
base::Bind(&DoOpenPnaclFile,
make_scoped_refptr(chrome_render_message_filter),
filename,
reply_msg))) {
NotifyRendererOfError(chrome_render_message_filter, reply_msg);
}
}
// This function is security sensitive. Be sure to check with a security
// person before you modify it.
bool PnaclCanOpenFile(const std::string& filename,
base::FilePath* file_to_open) {
if (filename.length() > kMaxFileLength)
return false;
if (filename.empty())
return false;
// Restrict character set of the file name to something really simple
// (a-z, 0-9, and underscores).
for (size_t i = 0; i < filename.length(); ++i) {
char charAt = filename[i];
if (charAt < 'a' || charAt > 'z')
if (charAt < '0' || charAt > '9')
if (charAt != '_')
return false;
}
// PNaCl must be installed.
base::FilePath pnacl_dir;
if (!PathService::Get(chrome::DIR_PNACL_COMPONENT, &pnacl_dir) ||
pnacl_dir.empty())
return false;
// Prepend the prefix to restrict files to a whitelisted set.
base::FilePath full_path = pnacl_dir.AppendASCII(
std::string(kExpectedFilePrefix) + filename);
*file_to_open = full_path;
return true;
}
void CreateTemporaryFile(
ChromeRenderMessageFilter* chrome_render_message_filter,
IPC::Message* reply_msg) {
if (!BrowserThread::PostTask(
BrowserThread::FILE, FROM_HERE,
base::Bind(&DoCreateTemporaryFile,
make_scoped_refptr(chrome_render_message_filter),
reply_msg))) {
NotifyRendererOfError(chrome_render_message_filter, reply_msg);
}
}
} // namespace pnacl_file_host
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