From 87eacab57a9544f7b824da7e87ace2655e020d12 Mon Sep 17 00:00:00 2001
From: Zim <zezeozue@google.com>
Date: Fri, 24 Jan 2020 01:03:09 +0000
Subject: Grant apps with WRITE_MEDIA_STORAGE legacy storage appop

An app can now have legacy storage access in 3 mutually exclusive
ways:
1. Targeting < Q
2. Targeting <=Q and explicitly requesting legacy access
3. Targeting <=Q and having the WRITE_MEDIA_STORAGE permission

In other words an app targeting R has no way to have legacy storage
access. Its only option is to request MANAGE_EXTERNAL_STORAGE access

Test: Verify via dumpsys the conditions above
Bug: 144914977
Change-Id: I3c868cd9b4da4083517dd64b3a3888aea4060f18
---
 .../policy/SoftRestrictedPermissionPolicy.java     | 27 ++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/policy/SoftRestrictedPermissionPolicy.java b/services/core/java/com/android/server/policy/SoftRestrictedPermissionPolicy.java
index f3a60185bfb6..81ec46634e8a 100644
--- a/services/core/java/com/android/server/policy/SoftRestrictedPermissionPolicy.java
+++ b/services/core/java/com/android/server/policy/SoftRestrictedPermissionPolicy.java
@@ -18,12 +18,14 @@ package com.android.server.policy;
 
 import static android.Manifest.permission.READ_EXTERNAL_STORAGE;
 import static android.Manifest.permission.WRITE_EXTERNAL_STORAGE;
+import static android.Manifest.permission.WRITE_MEDIA_STORAGE;
 import static android.app.AppOpsManager.OP_LEGACY_STORAGE;
 import static android.app.AppOpsManager.OP_NONE;
 import static android.content.pm.PackageManager.FLAG_PERMISSION_APPLY_RESTRICTION;
 import static android.content.pm.PackageManager.FLAG_PERMISSION_RESTRICTION_INSTALLER_EXEMPT;
 import static android.content.pm.PackageManager.FLAG_PERMISSION_RESTRICTION_SYSTEM_EXEMPT;
 import static android.content.pm.PackageManager.FLAG_PERMISSION_RESTRICTION_UPGRADE_EXEMPT;
+import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 
 import static java.lang.Integer.min;
 
@@ -114,6 +116,7 @@ public abstract class SoftRestrictedPermissionPolicy {
                 boolean shouldApplyRestriction;
                 final int targetSDK;
                 final boolean hasRequestedLegacyExternalStorage;
+                final boolean hasWriteMediaStorageGrantedForUid;
 
                 if (appInfo != null) {
                     PackageManager pm = context.getPackageManager();
@@ -123,11 +126,14 @@ public abstract class SoftRestrictedPermissionPolicy {
                     targetSDK = getMinimumTargetSDK(context, appInfo, user);
                     hasRequestedLegacyExternalStorage = hasUidRequestedLegacyExternalStorage(
                             appInfo.uid, context);
+                    hasWriteMediaStorageGrantedForUid = hasWriteMediaStorageGrantedForUid(
+                            appInfo.uid, context);
                 } else {
                     isWhiteListed = false;
                     shouldApplyRestriction = false;
                     targetSDK = 0;
                     hasRequestedLegacyExternalStorage = false;
+                    hasWriteMediaStorageGrantedForUid = false;
                 }
 
                 // We have a check in PermissionPolicyService.PermissionToOpSynchroniser.setUidMode
@@ -145,8 +151,9 @@ public abstract class SoftRestrictedPermissionPolicy {
                     }
                     @Override
                     public boolean mayAllowExtraAppOp() {
-                        return !shouldApplyRestriction && hasRequestedLegacyExternalStorage
-                                && targetSDK <= Build.VERSION_CODES.Q;
+                        return !shouldApplyRestriction && targetSDK <= Build.VERSION_CODES.Q
+                                && (hasRequestedLegacyExternalStorage
+                                        || hasWriteMediaStorageGrantedForUid);
                     }
                     @Override
                     public boolean mayDenyExtraAppOpIfGranted() {
@@ -201,6 +208,22 @@ public abstract class SoftRestrictedPermissionPolicy {
         return false;
     }
 
+    private static boolean hasWriteMediaStorageGrantedForUid(int uid, @NonNull Context context) {
+        PackageManager packageManager = context.getPackageManager();
+        String[] packageNames = packageManager.getPackagesForUid(uid);
+        if (packageNames == null) {
+            return false;
+        }
+
+        for (String packageName : packageNames) {
+            if (packageManager.checkPermission(WRITE_MEDIA_STORAGE, packageName)
+                    == PERMISSION_GRANTED) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     /**
      * @return If the permission can be granted
      */
-- 
cgit v1.2.3-59-g8ed1b