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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/renderer_host/renderer_sandboxed_process_launcher_delegate.h"
#include <string_view>
#include "base/strings/string_split.h"
#include "build/build_config.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/common/content_client.h"
#if BUILDFLAG(IS_WIN)
#include <windows.h>
#include "base/check.h"
#include "base/feature_list.h"
#include "base/metrics/histogram_functions.h"
#include "base/time/time.h"
#include "base/win/nt_status.h"
#include "sandbox/policy/features.h"
#include "sandbox/policy/win/sandbox_win.h"
#include "sandbox/win/src/sandbox_policy_base.h"
#include "sandbox/win/src/security_level.h"
#include "third_party/blink/public/common/switches.h"
#endif
#if BUILDFLAG(USE_ZYGOTE)
#include "content/public/common/content_switches.h"
#include "content/public/common/zygote/zygote_handle.h" // nogncheck
#endif
namespace content {
#if BUILDFLAG(USE_ZYGOTE)
ZygoteCommunication* RendererSandboxedProcessLauncherDelegate::GetZygote() {
const base::CommandLine& browser_command_line =
*base::CommandLine::ForCurrentProcess();
base::CommandLine::StringType renderer_prefix =
browser_command_line.GetSwitchValueNative(switches::kRendererCmdPrefix);
if (!renderer_prefix.empty())
return nullptr;
return GetGenericZygote();
}
#endif // BUILDFLAG(USE_ZYGOTE)
#if BUILDFLAG(IS_MAC)
bool RendererSandboxedProcessLauncherDelegate::EnableCpuSecurityMitigations() {
return true;
}
#endif // BUILDFLAG(IS_MAC)
sandbox::mojom::Sandbox
RendererSandboxedProcessLauncherDelegate::GetSandboxType() {
return sandbox::mojom::Sandbox::kRenderer;
}
#if BUILDFLAG(IS_WIN)
RendererSandboxedProcessLauncherDelegateWin::
RendererSandboxedProcessLauncherDelegateWin(
const base::CommandLine& cmd_line,
bool is_pdf_renderer,
bool is_jit_disabled)
: renderer_code_integrity_enabled_(
GetContentClient()->browser()->IsRendererCodeIntegrityEnabled()),
renderer_app_container_disabled_(
GetContentClient()->browser()->IsAppContainerDisabled(
sandbox::mojom::Sandbox::kRenderer)),
is_pdf_renderer_(is_pdf_renderer) {
// PDF renderers must be jitless.
CHECK(!is_pdf_renderer || is_jit_disabled);
if (is_jit_disabled) {
dynamic_code_can_be_disabled_ = true;
return;
}
if (cmd_line.HasSwitch(blink::switches::kJavaScriptFlags)) {
std::string js_flags =
cmd_line.GetSwitchValueASCII(blink::switches::kJavaScriptFlags);
std::vector<std::string_view> js_flag_list = base::SplitStringPiece(
js_flags, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
for (const auto& js_flag : js_flag_list) {
if (js_flag == "--jitless") {
// If v8 is running jitless then there is no need for the ability to
// mark writable pages as executable to be available to the process.
dynamic_code_can_be_disabled_ = true;
break;
}
}
}
}
std::string RendererSandboxedProcessLauncherDelegateWin::GetSandboxTag() {
if (is_pdf_renderer_) {
// All pdf renderers are jitless so only need one tag for these.
return sandbox::policy::SandboxWin::GetSandboxTagForDelegate(
"renderer-pdfium", GetSandboxType());
} else {
// Some renderers can be jitless so need different tags.
return sandbox::policy::SandboxWin::GetSandboxTagForDelegate(
dynamic_code_can_be_disabled_ ? "renderer-jitless" : "renderer",
GetSandboxType());
}
}
bool RendererSandboxedProcessLauncherDelegateWin::InitializeConfig(
sandbox::TargetConfig* config) {
DCHECK(!config->IsConfigured());
sandbox::policy::SandboxWin::AddBaseHandleClosePolicy(config);
ContentBrowserClient::AppContainerFlags ac_flags(
ContentBrowserClient::AppContainerFlags::kAppContainerFlagNone);
if (renderer_app_container_disabled_) {
ac_flags = ContentBrowserClient::AppContainerFlags::
kAppContainerFlagDisableAppContainer;
}
const std::wstring& sid =
GetContentClient()->browser()->GetAppContainerSidForSandboxType(
GetSandboxType(), ac_flags);
if (!sid.empty()) {
sandbox::policy::SandboxWin::AddAppContainerPolicy(config, sid.c_str());
}
// If the renderer process is protected by code integrity, more
// mitigations become available.
if (renderer_code_integrity_enabled_ && dynamic_code_can_be_disabled_) {
sandbox::MitigationFlags mitigation_flags =
config->GetDelayedProcessMitigations();
mitigation_flags |= sandbox::MITIGATION_DYNAMIC_CODE_DISABLE;
if (sandbox::SBOX_ALL_OK !=
config->SetDelayedProcessMitigations(mitigation_flags)) {
return false;
}
}
config->SetFilterEnvironment(/*filter=*/true);
ContentBrowserClient::ChildSpawnFlags flags(
ContentBrowserClient::ChildSpawnFlags::kChildSpawnFlagNone);
if (renderer_code_integrity_enabled_) {
flags = ContentBrowserClient::ChildSpawnFlags::
kChildSpawnFlagRendererCodeIntegrity;
}
return GetContentClient()->browser()->PreSpawnChild(
config, sandbox::mojom::Sandbox::kRenderer, flags);
}
void RendererSandboxedProcessLauncherDelegateWin::PostSpawnTarget(
base::ProcessHandle process) {
FILETIME creation_time, exit_time, kernel_time, user_time;
// Should never fail. If it does, then something really bad has happened, such
// as something external unsuspending the renderer process.
if (!::GetProcessTimes(process, &creation_time, &exit_time, &kernel_time,
&user_time)) {
return;
}
// These should always be zero but if they are not, then something on the
// client has triggered execution in the child process putting it into a
// undefined state. Try and detect this here to diagnose this happening in the
// wild.
base::UmaHistogramBoolean(
"BrowserRenderProcessHost.SuspendedChild.UserExecutionRecorded",
base::TimeDelta::FromFileTime(user_time).InMicroseconds() > 0);
base::UmaHistogramBoolean(
"BrowserRenderProcessHost.SuspendedChild.KernelExecutionRecorded",
base::TimeDelta::FromFileTime(kernel_time).InMicroseconds() > 0);
}
bool RendererSandboxedProcessLauncherDelegateWin::CetCompatible() {
// Disable CET for renderer because v8 deoptimization swaps stacks in a
// non-compliant way. CET can be enabled where the renderer is known to
// be jitless.
return dynamic_code_can_be_disabled_;
}
bool RendererSandboxedProcessLauncherDelegateWin::
ShouldUseUntrustedMojoInvitation() {
return true;
}
#endif // BUILDFLAG(IS_WIN)
} // namespace content
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