| /* |
| * Copyright (C) 2019 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.server.integrity.engine; |
| |
| import static android.content.integrity.Rule.DENY; |
| import static android.content.integrity.Rule.FORCE_ALLOW; |
| |
| import android.annotation.NonNull; |
| import android.content.integrity.AppInstallMetadata; |
| import android.content.integrity.Rule; |
| |
| import com.android.server.integrity.model.IntegrityCheckResult; |
| |
| import java.util.List; |
| import java.util.stream.Collectors; |
| |
| /** |
| * A helper class for evaluating rules against app install metadata to find if there are matching |
| * rules. |
| */ |
| final class RuleEvaluator { |
| |
| /** |
| * Match the list of rules against an app install metadata. |
| * |
| * <p>Rules must be in disjunctive normal form (DNF). A rule should contain AND'ed formulas |
| * only. All rules are OR'ed together by default. |
| * |
| * @param rules The list of rules to evaluate. |
| * @param appInstallMetadata Metadata of the app to be installed, and to evaluate the rules |
| * against. |
| * @return result of the integrity check |
| */ |
| @NonNull |
| static IntegrityCheckResult evaluateRules( |
| List<Rule> rules, AppInstallMetadata appInstallMetadata) { |
| |
| // Identify the rules that match the {@code appInstallMetadata}. |
| List<Rule> matchedRules = |
| rules.stream() |
| .filter(rule -> rule.getFormula().matches(appInstallMetadata)) |
| .collect(Collectors.toList()); |
| |
| // Identify the matched power allow rules and terminate early if we have any. |
| List<Rule> matchedPowerAllowRules = |
| matchedRules.stream() |
| .filter(rule -> rule.getEffect() == FORCE_ALLOW) |
| .collect(Collectors.toList()); |
| |
| if (!matchedPowerAllowRules.isEmpty()) { |
| return IntegrityCheckResult.allow(matchedPowerAllowRules); |
| } |
| |
| // Identify the matched deny rules. |
| List<Rule> matchedDenyRules = |
| matchedRules.stream() |
| .filter(rule -> rule.getEffect() == DENY) |
| .collect(Collectors.toList()); |
| |
| if (!matchedDenyRules.isEmpty()) { |
| return IntegrityCheckResult.deny(matchedDenyRules); |
| } |
| |
| // When no rules are denied, return default allow result. |
| return IntegrityCheckResult.allow(); |
| } |
| } |