Enforce overriding methods for IPlatformCompat

Restrict the ability of callers to IPlatformCompat.setOverrides and
IPlatformCompat.clearOverride, depending on the type of build and/or
whether the app is debuggable.

Bug: 144552011
Test: atest PlatformCompatTest
Test: atest CompatConfigTest
Change-Id: Ibff7db73d7867735853aa2ddde7c14a12625b3dc

5 files changed, 233 insertions, 0 deletions

diff --git a/core/java/com/android/internal/compat/AndroidBuildClassifier.java b/core/java/com/android/internal/compat/AndroidBuildClassifier.java
new file mode 100644
index 000000000000..0b937fad7df1
--- /dev/null
+++ b/core/java/com/android/internal/compat/AndroidBuildClassifier.java
@@ -0,0 +1,34 @@
+/*
+ * 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.internal.compat;
+
+import android.os.Build;
+
+/**
+ * Platform private class for determining the type of Android build installed.
+ *
+ */
+public class AndroidBuildClassifier {
+
+    public boolean isDebuggableBuild() {
+        return Build.IS_DEBUGGABLE;
+    }
+
+    public boolean isFinalBuild() {
+        return "REL".equals(Build.VERSION.CODENAME);
+    }
+}
diff --git a/core/java/com/android/internal/compat/IOverrideValidator.aidl b/core/java/com/android/internal/compat/IOverrideValidator.aidl
new file mode 100644
index 000000000000..add4708863aa
--- /dev/null
+++ b/core/java/com/android/internal/compat/IOverrideValidator.aidl
@@ -0,0 +1,38 @@
+/*
+ * 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.internal.compat;
+
+import android.content.pm.ApplicationInfo;
+
+import com.android.internal.compat.OverrideAllowedState;
+
+/**
+ * Platform private API for determining whether a changeId can be overridden.
+ *
+ * {@hide}
+ */
+interface IOverrideValidator
+{
+    /**
+     * Validation function.
+     * @param changeId    id of the change to be toggled on or off.
+     * @param packageName package of the app for which the change should be overridden.
+     * @return {@link OverrideAllowedState} specifying whether the change can be overridden for
+     * the given package or a reason why not.
+     */
+    OverrideAllowedState getOverrideAllowedState(long changeId, String packageName);
+}
diff --git a/core/java/com/android/internal/compat/IPlatformCompat.aidl b/core/java/com/android/internal/compat/IPlatformCompat.aidl
index 7dcb12c9e72b..4c203d394759 100644
--- a/core/java/com/android/internal/compat/IPlatformCompat.aidl
+++ b/core/java/com/android/internal/compat/IPlatformCompat.aidl
@@ -17,6 +17,7 @@
 package com.android.internal.compat;
 
 import android.content.pm.ApplicationInfo;
+import com.android.internal.compat.IOverrideValidator;
 import java.util.Map;
 
 parcelable CompatibilityChangeConfig;
@@ -195,4 +196,9 @@ interface IPlatformCompat
      * @return An array of {@link CompatChangeInfo} known to the service.
      */
     CompatibilityChangeInfo[] listAllChanges();
+
+    /**
+     * Get an instance that can determine whether a changeid can be overridden for a package name.
+     */
+    IOverrideValidator getOverrideValidator();
 }
diff --git a/core/java/com/android/internal/compat/OverrideAllowedState.aidl b/core/java/com/android/internal/compat/OverrideAllowedState.aidl
new file mode 100644
index 000000000000..10ceac786841
--- /dev/null
+++ b/core/java/com/android/internal/compat/OverrideAllowedState.aidl
@@ -0,0 +1,19 @@
+/*
+ * 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.internal.compat;
+
+parcelable OverrideAllowedState;
\ No newline at end of file
diff --git a/core/java/com/android/internal/compat/OverrideAllowedState.java b/core/java/com/android/internal/compat/OverrideAllowedState.java
new file mode 100644
index 000000000000..0c8aefebac0e
--- /dev/null
+++ b/core/java/com/android/internal/compat/OverrideAllowedState.java
@@ -0,0 +1,136 @@
+/*
+ * 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.internal.compat;
+
+import android.annotation.IntDef;
+import android.annotation.NonNull;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * This class contains all the possible override allowed states.
+ */
+public final class OverrideAllowedState implements Parcelable {
+    @IntDef({
+            ALLOWED,
+            DISABLED_NOT_DEBUGGABLE,
+            DISABLED_NON_TARGET_SDK,
+            DISABLED_TARGET_SDK_TOO_HIGH,
+            PACKAGE_DOES_NOT_EXIST
+    })
+    @Retention(RetentionPolicy.SOURCE)
+    public @interface State {
+    }
+
+    /**
+     * Change can be overridden.
+     */
+    public static final int ALLOWED = 0;
+    /**
+     * Change cannot be overridden, due to the app not being debuggable.
+     */
+    public static final int DISABLED_NOT_DEBUGGABLE = 1;
+    /**
+     * Change cannot be overridden, due to the build being non-debuggable and the change being
+     * non-targetSdk.
+     */
+    public static final int DISABLED_NON_TARGET_SDK = 2;
+    /**
+     * Change cannot be overridden, due to the app's targetSdk being above the change's targetSdk.
+     */
+    public static final int DISABLED_TARGET_SDK_TOO_HIGH = 3;
+    /**
+     * Package does not exist.
+     */
+    public static final int PACKAGE_DOES_NOT_EXIST = 4;
+
+    @State
+    public final int state;
+    public final int appTargetSdk;
+    public final int changeIdTargetSdk;
+
+    private OverrideAllowedState(Parcel parcel) {
+        state = parcel.readInt();
+        appTargetSdk = parcel.readInt();
+        changeIdTargetSdk = parcel.readInt();
+    }
+
+    public OverrideAllowedState(@State int state, int appTargetSdk, int changeIdTargetSdk) {
+        this.state = state;
+        this.appTargetSdk = appTargetSdk;
+        this.changeIdTargetSdk = changeIdTargetSdk;
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(Parcel out, int flags) {
+        out.writeInt(state);
+        out.writeInt(appTargetSdk);
+        out.writeInt(changeIdTargetSdk);
+    }
+
+    /**
+     * Enforces the policy for overriding compat changes.
+     *
+     * @param changeId    the change id that was attempted to be overridden.
+     * @param packageName the package for which the attempt was made.
+     * @throws SecurityException if the policy forbids this operation.
+     */
+    public void enforce(long changeId, String packageName)
+            throws SecurityException {
+        switch (state) {
+            case ALLOWED:
+                return;
+            case DISABLED_NOT_DEBUGGABLE:
+                throw new SecurityException(
+                        "Cannot override a change on a non-debuggable app and user build.");
+            case DISABLED_NON_TARGET_SDK:
+                throw new SecurityException(
+                        "Cannot override a default enabled/disabled change on a user build.");
+            case DISABLED_TARGET_SDK_TOO_HIGH:
+                throw new SecurityException(String.format(
+                        "Cannot override %1$d for %2$s because the app's targetSdk (%3$d) is "
+                                + "above the change's targetSdk threshold (%4$d)",
+                        changeId, packageName, appTargetSdk, changeIdTargetSdk));
+            case PACKAGE_DOES_NOT_EXIST:
+                throw new SecurityException(String.format(
+                        "Cannot override %1$d for %2$s because the package does not exist, and "
+                                + "the change is targetSdk gated.",
+                        changeId, packageName));
+        }
+    }
+
+    public static final @NonNull
+            Parcelable.Creator<OverrideAllowedState> CREATOR =
+                new Parcelable.Creator<OverrideAllowedState>() {
+                public OverrideAllowedState createFromParcel(Parcel parcel) {
+                    OverrideAllowedState info = new OverrideAllowedState(parcel);
+                    return info;
+                }
+
+                public OverrideAllowedState[] newArray(int size) {
+                    return new OverrideAllowedState[size];
+                }
+            };
+}