Define rule structure

Defines a model for the structure of rules to be represented in storage
and in the rule evaluation engine.

Bug: 141979167
Test: N/A
Change-Id: I1f80b5c53e8e6cf900b211cab31758e0656db133

services/core/java/com/android/server/integrity/engine/RuleEvaluationEngine.java

@@ -16,6 +16,8 @@
 
 package com.android.server.integrity.engine;
 
+import com.android.server.integrity.model.Rule;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -34,7 +36,7 @@ public final class RuleEvaluationEngine {
 
     // The subset of rules loaded to be used to evaluate an app install request.
     // TODO: Load rules relevant to app installs.
-    private List<String> mRules;
+    private List<Rule> mRules;
 
     private RuleEvaluationEngine() {
         // Initialize rules with the empty rule set.

services/core/java/com/android/server/integrity/engine/RuleLoader.java

@@ -16,6 +16,8 @@
 
 package com.android.server.integrity.engine;
 
+import com.android.server.integrity.model.Rule;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -37,22 +39,22 @@ import java.util.List;
  */
 final class RuleLoader {
 
-    List<String> loadRulesByPackageName(String packageName) {
+    List<Rule> loadRulesByPackageName(String packageName) {
         // TODO: Add logic based on rule storage.
         return new ArrayList<>();
     }
 
-    List<String> loadRulesByAppCertificate(String appCertificate) {
+    List<Rule> loadRulesByAppCertificate(String appCertificate) {
         // TODO: Add logic based on rule storage.
         return new ArrayList<>();
     }
 
-    List<String> loadRulesByInstallerName(String installerName) {
+    List<Rule> loadRulesByInstallerName(String installerName) {
         // TODO: Add logic based on rule storage.
         return new ArrayList<>();
     }
 
-    List<String> loadRulesByInstallerCertificate(String installerCertificate) {
+    List<Rule> loadRulesByInstallerCertificate(String installerCertificate) {
         // TODO: Add logic based on rule storage.
         return new ArrayList<>();
     }

services/core/java/com/android/server/integrity/model/AppInstallMetadata.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.integrity.engine;
+package com.android.server.integrity.model;
 
 /**
  * The app install metadata.
@@ -32,7 +32,7 @@ public final class AppInstallMetadata {
     final int mVersionCode;
     final boolean mIsPreInstalled;
 
-    AppInstallMetadata(String packageName, String appCertificate, String installerName,
+    public AppInstallMetadata(String packageName, String appCertificate, String installerName,
             String installerCertificate, int versionCode, boolean isPreInstalled) {
         this.mPackageName = packageName;
         this.mAppCertificate = appCertificate;

services/core/java/com/android/server/integrity/model/Rule.java

@@ -0,0 +1,128 @@
+/*
+ * 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.model;
+
+import android.annotation.Nullable;
+
+/**
+ * Represent rules to be used in the rule evaluation engine to match against app installs.
+ */
+public final class Rule {
+
+    enum Key {
+        PACKAGE_NAME,
+        APP_CERTIFICATE,
+        INSTALLER_NAME,
+        INSTALLER_CERTIFICATE,
+        VERSION_CODE,
+        PRE_INSTALLED
+    }
+
+    enum Effect {
+        DENY
+    }
+
+    enum Operator {
+        EQ,
+        LT,
+        LE,
+        GT,
+        GE
+    }
+
+    enum Connector {
+        AND,
+        OR,
+        NOT
+    }
+
+    final Formula mFormula;
+    final Effect mEffect;
+
+    public Rule(Formula formula, Effect effect) {
+        this.mFormula = formula;
+        this.mEffect = effect;
+    }
+
+    /**
+     * Represents a rule logic/content.
+     */
+    abstract class Formula {
+
+    }
+
+    /**
+     * Represents a simple formula consisting of an app install metadata field and a value.
+     */
+    public final class AtomicFormula extends Formula {
+
+        final Key mKey;
+        final Operator mOperator;
+
+        // The value of a key can take either 1 of 3 forms: String, Integer, or Boolean.
+        // It cannot have multiple values.
+        @Nullable
+        final String mStringValue;
+        @Nullable
+        final Integer mIntValue;
+        @Nullable
+        final Boolean mBoolValue;
+
+        public AtomicFormula(Key key, Operator operator, String stringValue) {
+            // TODO: Add validators
+            this.mKey = key;
+            this.mOperator = operator;
+            this.mStringValue = stringValue;
+            this.mIntValue = null;
+            this.mBoolValue = null;
+        }
+
+        public AtomicFormula(Key key, Operator operator, Integer intValue) {
+            // TODO: Add validators
+            this.mKey = key;
+            this.mOperator = operator;
+            this.mStringValue = null;
+            this.mIntValue = intValue;
+            this.mBoolValue = null;
+        }
+
+        public AtomicFormula(Key key, Operator operator, Boolean boolValue) {
+            // TODO: Add validators
+            this.mKey = key;
+            this.mOperator = operator;
+            this.mStringValue = null;
+            this.mIntValue = null;
+            this.mBoolValue = boolValue;
+        }
+    }
+
+    /**
+     * Represents a complex formula consisting of other simple and complex formulas.
+     */
+    public final class OpenFormula extends Formula {
+
+        final Connector mConnector;
+        final Formula mMainFormula;
+        final Formula mAuxiliaryFormula;
+
+        public OpenFormula(Connector connector, Formula mainFormula, Formula auxiliaryFormula) {
+            this.mConnector = connector;
+            this.mMainFormula = mainFormula;
+            this.mAuxiliaryFormula = auxiliaryFormula;
+        }
+    }
+}