Respond to API council feedback.

Move aggressive allocation to @SystemApi, which means we can hide
the "flags" API variants.

Remove UUID APIs, since we should use existing Serializable APIs.

Relax permission checks to allow apps to ask for their own stats.

Improve docs.

Test: cts-tradefed run commandAndExit cts-dev -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.StorageHostTest
Bug: 37534687, 37534941, 37718184, 37738770
Change-Id: I6a763fb3ab3169c8d3329765bb31e1ee08d9ced7

1 files changed, 25 insertions, 11 deletions

diff --git a/services/usage/java/com/android/server/usage/StorageStatsService.java b/services/usage/java/com/android/server/usage/StorageStatsService.java
index 2ebf5fc1c533..e13665bed275 100644
--- a/services/usage/java/com/android/server/usage/StorageStatsService.java
+++ b/services/usage/java/com/android/server/usage/StorageStatsService.java
@@ -157,7 +157,7 @@ public class StorageStatsService extends IStorageStatsManager.Stub {
 
     @Override
     public long getTotalBytes(String volumeUuid, String callingPackage) {
-        enforcePermission(Binder.getCallingUid(), callingPackage);
+        // NOTE: No permissions required
 
         if (volumeUuid == StorageManager.UUID_PRIVATE_INTERNAL) {
             return FileUtils.roundStorageSize(mStorage.getPrimaryStorageSize());
@@ -173,7 +173,7 @@ public class StorageStatsService extends IStorageStatsManager.Stub {
 
     @Override
     public long getFreeBytes(String volumeUuid, String callingPackage) {
-        enforcePermission(Binder.getCallingUid(), callingPackage);
+        // NOTE: No permissions required
 
         long cacheBytes = 0;
         final long token = Binder.clearCallingIdentity();
@@ -187,14 +187,14 @@ public class StorageStatsService extends IStorageStatsManager.Stub {
         }
 
         if (volumeUuid == StorageManager.UUID_PRIVATE_INTERNAL) {
-            return Environment.getDataDirectory().getUsableSpace() + cacheBytes;
+            return Environment.getDataDirectory().getFreeSpace() + cacheBytes;
         } else {
             final VolumeInfo vol = mStorage.findVolumeByUuid(volumeUuid);
             if (vol == null) {
                 throw new ParcelableException(
                         new IOException("Failed to find storage device for UUID " + volumeUuid));
             }
-            return vol.getPath().getUsableSpace() + cacheBytes;
+            return vol.getPath().getFreeSpace() + cacheBytes;
         }
     }
 
@@ -213,7 +213,6 @@ public class StorageStatsService extends IStorageStatsManager.Stub {
     @Override
     public StorageStats queryStatsForPackage(String volumeUuid, String packageName, int userId,
             String callingPackage) {
-        enforcePermission(Binder.getCallingUid(), callingPackage);
         if (userId != UserHandle.getCallingUserId()) {
             mContext.enforceCallingOrSelfPermission(
                     android.Manifest.permission.INTERACT_ACROSS_USERS, TAG);
@@ -227,6 +226,12 @@ public class StorageStatsService extends IStorageStatsManager.Stub {
             throw new ParcelableException(e);
         }
 
+        if (Binder.getCallingUid() == appInfo.uid) {
+            // No permissions required when asking about themselves
+        } else {
+            enforcePermission(Binder.getCallingUid(), callingPackage);
+        }
+
         if (mPackage.getPackagesForUid(appInfo.uid).length == 1) {
             // Only one package inside UID means we can fast-path
             return queryStatsForUid(volumeUuid, appInfo.uid, callingPackage);
@@ -257,14 +262,19 @@ public class StorageStatsService extends IStorageStatsManager.Stub {
 
     @Override
     public StorageStats queryStatsForUid(String volumeUuid, int uid, String callingPackage) {
-        enforcePermission(Binder.getCallingUid(), callingPackage);
-        if (UserHandle.getUserId(uid) != UserHandle.getCallingUserId()) {
+        final int userId = UserHandle.getUserId(uid);
+        final int appId = UserHandle.getAppId(uid);
+
+        if (userId != UserHandle.getCallingUserId()) {
             mContext.enforceCallingOrSelfPermission(
                     android.Manifest.permission.INTERACT_ACROSS_USERS, TAG);
         }
 
-        final int userId = UserHandle.getUserId(uid);
-        final int appId = UserHandle.getAppId(uid);
+        if (Binder.getCallingUid() == uid) {
+            // No permissions required when asking about themselves
+        } else {
+            enforcePermission(Binder.getCallingUid(), callingPackage);
+        }
 
         final String[] packageNames = mPackage.getPackagesForUid(uid);
         final long[] ceDataInodes = new long[packageNames.length];
@@ -304,12 +314,14 @@ public class StorageStatsService extends IStorageStatsManager.Stub {
 
     @Override
     public StorageStats queryStatsForUser(String volumeUuid, int userId, String callingPackage) {
-        enforcePermission(Binder.getCallingUid(), callingPackage);
         if (userId != UserHandle.getCallingUserId()) {
             mContext.enforceCallingOrSelfPermission(
                     android.Manifest.permission.INTERACT_ACROSS_USERS, TAG);
         }
 
+        // Always require permission to see user-level stats
+        enforcePermission(Binder.getCallingUid(), callingPackage);
+
         final int[] appIds = getAppIds(userId);
         final PackageStats stats = new PackageStats(TAG);
         try {
@@ -329,12 +341,14 @@ public class StorageStatsService extends IStorageStatsManager.Stub {
     @Override
     public ExternalStorageStats queryExternalStatsForUser(String volumeUuid, int userId,
             String callingPackage) {
-        enforcePermission(Binder.getCallingUid(), callingPackage);
         if (userId != UserHandle.getCallingUserId()) {
             mContext.enforceCallingOrSelfPermission(
                     android.Manifest.permission.INTERACT_ACROSS_USERS, TAG);
         }
 
+        // Always require permission to see user-level stats
+        enforcePermission(Binder.getCallingUid(), callingPackage);
+
         final int[] appIds = getAppIds(userId);
         final long[] stats;
         try {