Preventing a shortcut which requires permissions from being added to

homescreen

A shortcut can be added by any app as INSTALL_SHORTCUT is a normal
level permission. But the intent is actually launched by the launcher
app which can have other permission as well.

> When adding a shortcut from the broadcast, verify that the intent does
not require any permission
> When adding a shortcut using the two-step drop process, verify that
the source app also has the permission to create such a shortcut

Bug: 30778130
Change-Id: I710a490d69019dc25709db5a97020c20d9325007

src/com/android/launcher3/util/PackageManagerHelper.java

@@ -16,10 +16,15 @@
 
 package com.android.launcher3.util;
 
+import android.app.AppOpsManager;
+import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.pm.ResolveInfo;
+import android.os.Build;
+import android.text.TextUtils;
 
 import com.android.launcher3.Utilities;
 
@@ -96,4 +101,53 @@ public class PackageManagerHelper {
         }
         return excludePackages.get(0);
     }
+
+    /**
+     * Returns true if {@param srcPackage} has the permission required to start the activity from
+     * {@param intent}. If {@param srcPackage} is null, then the activity should not need
+     * any permissions
+     */
+    public static boolean hasPermissionForActivity(Context context, Intent intent,
+            String srcPackage) {
+        PackageManager pm = context.getPackageManager();
+        ResolveInfo target = pm.resolveActivity(intent, 0);
+        if (target == null) {
+            // Not a valid target
+            return false;
+        }
+        if (TextUtils.isEmpty(target.activityInfo.permission)) {
+            // No permission is needed
+            return true;
+        }
+        if (TextUtils.isEmpty(srcPackage)) {
+            // The activity requires some permission but there is no source.
+            return false;
+        }
+
+        // Source does not have sufficient permissions.
+        if(pm.checkPermission(target.activityInfo.permission, srcPackage) !=
+                PackageManager.PERMISSION_GRANTED) {
+            return false;
+        }
+
+        if (!Utilities.ATLEAST_MARSHMALLOW) {
+            // These checks are sufficient for below M devices.
+            return true;
+        }
+
+        // On M and above also check AppOpsManager for compatibility mode permissions.
+        if (TextUtils.isEmpty(AppOpsManager.permissionToOp(target.activityInfo.permission))) {
+            // There is no app-op for this permission, which could have been disabled.
+            return true;
+        }
+
+        // There is no direct way to check if the app-op is allowed for a particular app. Since
+        // app-op is only enabled for apps running in compatibility mode, simply block such apps.
+
+        try {
+            return pm.getApplicationInfo(srcPackage, 0).targetSdkVersion >= Build.VERSION_CODES.M;
+        } catch (NameNotFoundException e) { }
+
+        return false;
+    }
 }