Public volumes belong to a single user.
When a public (vfat) device is inserted, it's strongly associated
with the current foreground user, and no other users should be able
to access it, since otherwise that would be a cross-user data leak.
To use the device under a different user, switch users and then
eject/remount the device.
Test: verified user isolation of USB drive
Bug: 32523490
Change-Id: I590c791996f1fea8d78f625dc942d149f1f41614
(cherry picked from commit 8b38d083c42e2706e1ff5a1410fa61d1f5dea3f5)
diff --git a/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java b/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
index 3ef9b8e..10e5dcc 100644
--- a/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
+++ b/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
@@ -161,7 +161,8 @@
final VolumeInfo privateVol = mStorageManager.findPrivateForEmulated(volume);
title = mStorageManager.getBestVolumeDescription(privateVol);
}
- } else if (volume.getType() == VolumeInfo.TYPE_PUBLIC) {
+ } else if (volume.getType() == VolumeInfo.TYPE_PUBLIC
+ && volume.getMountUserId() == userId) {
rootId = volume.getFsUuid();
title = mStorageManager.getBestVolumeDescription(volume);
} else {
