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Fix issue #72151749: Lock down 'clear cache' functionality to...

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...only system signature

Apps that hold the original permission are silently ignored.  There
is a new internal permission you must hold to actually delete cache
files.

Test: booted and run, can still clear cache in settings.
Bug: 72151749
Change-Id: I47a5cb697e1a4fa3665ac71aaabcda57bef7b561
This commit is contained in:
Dianne Hackborn
2018-02-09 14:12:56 -08:00
parent 4945e8e376
commit 1b794faeac
2 changed files with 22 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
core/res/AndroidManifest.xml
View File

@@ -2955,11 +2955,16 @@
<permission android:name="android.permission.MANAGE_SCOPED_ACCESS_DIRECTORY_PERMISSIONS"
android:protectionLevel="signature" />
<!-- @SystemApi Allows an application to delete cache files.
<p>Not for use by third-party applications. -->
<!-- @SystemApi Old permission for deleting an app's cache files, no longer used,
but signals for us to quietly ignore calls instead of throwing an exception. -->
<permission android:name="android.permission.DELETE_CACHE_FILES"
android:protectionLevel="signature|privileged" />
<!-- Allows an application to delete cache files.
@hide -->
<permission android:name="android.permission.INTERNAL_DELETE_CACHE_FILES"
android:protectionLevel="signature" />
<!-- @SystemApi Allows an application to delete packages.
<p>Not for use by third-party applications.
<p>Starting in {@link android.os.Build.VERSION_CODES#N}, user confirmation is requested

17
services/core/java/com/android/server/pm/PackageManagerService.java
View File

@@ -19102,8 +19102,21 @@ public class PackageManagerService extends IPackageManager.Stub
public void deleteApplicationCacheFilesAsUser(final String packageName, final int userId,
final IPackageDataObserver observer) {
final int callingUid = Binder.getCallingUid();
mContext.enforceCallingOrSelfPermission(
android.Manifest.permission.DELETE_CACHE_FILES, null);
if (mContext.checkCallingOrSelfPermission(
android.Manifest.permission.INTERNAL_DELETE_CACHE_FILES)
!= PackageManager.PERMISSION_GRANTED) {
// If the caller has the old delete cache permission, silently ignore. Else throw.
if (mContext.checkCallingOrSelfPermission(
android.Manifest.permission.DELETE_CACHE_FILES)
== PackageManager.PERMISSION_GRANTED) {
Slog.w(TAG, "Calling uid " + callingUid + " does not have " +
android.Manifest.permission.INTERNAL_DELETE_CACHE_FILES +
", silently ignoring");
return;
}
mContext.enforceCallingOrSelfPermission(
android.Manifest.permission.INTERNAL_DELETE_CACHE_FILES, null);
}
mPermissionManager.enforceCrossUserPermission(callingUid, userId,
/* requireFullPermission= */ true, /* checkShell= */ false,
"delete application cache files");