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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "Policy.h"
#include <windows.h>
#include <shlwapi.h>
#include <fstream>
#include "common.h"
#include "Registry.h"
#include "UtfConvert.h"
#include "json/json.h"
#include "mozilla/HelperMacros.h"
#include "mozilla/Maybe.h"
#include "mozilla/WinHeaderOnlyUtils.h"
// There is little logging or error handling in this file, because the file and
// registry values we are reading here are normally absent, so never finding
// anything that we look for at all would not be an error worth generating an
// event log for.
#define AGENT_POLICY_NAME "DisableDefaultBrowserAgent"
#define TELEMETRY_POLICY_NAME "DisableTelemetry"
// The Firefox policy engine hardcodes the string "Mozilla" in its registry
// key accesses rather than using the configured vendor name, so we should do
// the same here to be sure we're compatible with it.
#define POLICY_REGKEY_NAME L"SOFTWARE\\Policies\\Mozilla\\" MOZ_APP_BASENAME
namespace mozilla::default_agent {
// This enum is the return type for the functions that check policy values.
enum class PolicyState {
Enabled, // There is a policy explicitly set to enabled
Disabled, // There is a policy explicitly set to disabled
NoPolicy, // This policy isn't configured
};
static PolicyState FindPolicyInRegistry(HKEY rootKey,
const wchar_t* policyName) {
HKEY rawRegKey = nullptr;
RegOpenKeyExW(rootKey, POLICY_REGKEY_NAME, 0, KEY_READ, &rawRegKey);
nsAutoRegKey regKey(rawRegKey);
if (!regKey) {
return PolicyState::NoPolicy;
}
// If this key is empty and doesn't have any actual policies in it,
// treat that the same as the key not existing and return no result.
DWORD numSubKeys = 0, numValues = 0;
LSTATUS ls = RegQueryInfoKeyW(regKey.get(), nullptr, nullptr, nullptr,
&numSubKeys, nullptr, nullptr, &numValues,
nullptr, nullptr, nullptr, nullptr);
if (ls != ERROR_SUCCESS) {
return PolicyState::NoPolicy;
}
DWORD policyValue = UINT32_MAX;
DWORD policyValueSize = sizeof(policyValue);
ls = RegGetValueW(regKey.get(), nullptr, policyName, RRF_RT_REG_DWORD,
nullptr, &policyValue, &policyValueSize);
if (ls != ERROR_SUCCESS) {
return PolicyState::NoPolicy;
}
return policyValue == 0 ? PolicyState::Disabled : PolicyState::Enabled;
}
static PolicyState FindPolicyInFile(const char* policyName) {
mozilla::UniquePtr<wchar_t[]> thisBinaryPath = mozilla::GetFullBinaryPath();
if (!PathRemoveFileSpecW(thisBinaryPath.get())) {
return PolicyState::NoPolicy;
}
wchar_t policiesFilePath[MAX_PATH] = L"";
if (!PathCombineW(policiesFilePath, thisBinaryPath.get(), L"distribution")) {
return PolicyState::NoPolicy;
}
if (!PathAppendW(policiesFilePath, L"policies.json")) {
return PolicyState::NoPolicy;
}
// We need a narrow string-based std::ifstream because that's all jsoncpp can
// use; that means we need to supply it the file path as a narrow string.
Utf16ToUtf8Result policiesFilePathToUtf8 = Utf16ToUtf8(policiesFilePath);
if (policiesFilePathToUtf8.isErr()) {
return PolicyState::NoPolicy;
}
std::string policiesFilePathA = policiesFilePathToUtf8.unwrap();
Json::Value jsonRoot;
std::ifstream stream(policiesFilePathA);
Json::Reader().parse(stream, jsonRoot);
if (jsonRoot.isObject() && jsonRoot.isMember("Policies") &&
jsonRoot["Policies"].isObject()) {
if (jsonRoot["Policies"].isMember(policyName) &&
jsonRoot["Policies"][policyName].isBool()) {
return jsonRoot["Policies"][policyName].asBool() ? PolicyState::Enabled
: PolicyState::Disabled;
} else {
return PolicyState::NoPolicy;
}
}
return PolicyState::NoPolicy;
}
static PolicyState IsDisabledByPref(const wchar_t* prefRegValue) {
auto prefValueResult =
RegistryGetValueBool(IsPrefixed::Prefixed, prefRegValue);
if (prefValueResult.isErr()) {
return PolicyState::NoPolicy;
}
auto prefValue = prefValueResult.unwrap();
if (prefValue.isNothing()) {
return PolicyState::NoPolicy;
}
return prefValue.value() ? PolicyState::Enabled : PolicyState::Disabled;
}
// Everything we call from this function wants wide strings, except for jsoncpp,
// which cannot work with them at all, so at some point we need both formats.
// It's awkward to take both formats as individual arguments, but it would be
// more awkward to take one and runtime convert it to the other, or to turn
// this function into a macro so that the preprocessor can trigger the
// conversion for us, so this is what we've got.
static bool IsThingDisabled(const char* thing, const wchar_t* wideThing) {
// The logic here is intended to be the same as that used by Firefox's policy
// engine implementation; they should be kept in sync. We have added the pref
// check at the end though, since that's our own custom mechanism.
PolicyState state = FindPolicyInRegistry(HKEY_LOCAL_MACHINE, wideThing);
if (state == PolicyState::NoPolicy) {
state = FindPolicyInRegistry(HKEY_CURRENT_USER, wideThing);
}
if (state == PolicyState::NoPolicy) {
state = FindPolicyInFile(thing);
}
if (state == PolicyState::NoPolicy) {
state = IsDisabledByPref(wideThing);
}
return state == PolicyState::Enabled ? true : false;
}
bool IsAgentDisabled() {
return IsThingDisabled(AGENT_POLICY_NAME, L"" AGENT_POLICY_NAME);
}
bool IsTelemetryDisabled() {
return IsThingDisabled(TELEMETRY_POLICY_NAME, L"" TELEMETRY_POLICY_NAME);
}
} // namespace mozilla::default_agent
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