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Revoke storage on SDK downgrade or new full storage request

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When an app downgrades from above API 28 to below, or when an app begins
requesting full storage in api 29, revoke storage permissions

Test: Atest StorageEscalationTest
Bug: 171430330
Change-Id: Ia6bd5658b77a26ab15fea013ec875050457473e0
This commit is contained in:
Nate Myren
2020-10-26 11:43:27 -07:00
parent 54bfaf7af9
commit dc90670bb4
1 changed files with 49 additions and 0 deletions
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49
services/core/java/com/android/server/pm/permission/PermissionManagerService.java
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@@ -205,6 +205,9 @@ public class PermissionManagerService extends IPermissionManager.Stub {
private static final int USER_PERMISSION_FLAGS = FLAG_PERMISSION_USER_SET
| FLAG_PERMISSION_USER_FIXED;
/** All storage permissions */
private static final List<String> STORAGE_PERMISSIONS = new ArrayList<>();
/** If the permission of the value is granted, so is the key */
private static final Map<String, String> FULLER_PERMISSION_MAP = new HashMap<>();
@@ -213,6 +216,9 @@ public class PermissionManagerService extends IPermissionManager.Stub {
Manifest.permission.ACCESS_FINE_LOCATION);
FULLER_PERMISSION_MAP.put(Manifest.permission.INTERACT_ACROSS_USERS,
Manifest.permission.INTERACT_ACROSS_USERS_FULL);
STORAGE_PERMISSIONS.add(Manifest.permission.READ_EXTERNAL_STORAGE);
STORAGE_PERMISSIONS.add(Manifest.permission.WRITE_EXTERNAL_STORAGE);
STORAGE_PERMISSIONS.add(Manifest.permission.ACCESS_MEDIA_LOCATION);
}
/** Lock to protect internal data access */
@@ -2357,6 +2363,48 @@ public class PermissionManagerService extends IPermissionManager.Stub {
}
}
/**
* If the app is updated, and has scoped storage permissions, then it is possible that the
* app updated in an attempt to get unscoped storage. If so, revoke all storage permissions.
* @param newPackage The new package that was installed
* @param oldPackage The old package that was updated
*/
private void revokeStoragePermissionsIfScopeExpandedInternal(
@NonNull AndroidPackage newPackage,
@NonNull AndroidPackage oldPackage) {
boolean downgradedSdk = oldPackage.getTargetSdkVersion() >= Build.VERSION_CODES.Q
&& newPackage.getTargetSdkVersion() < Build.VERSION_CODES.Q;
boolean upgradedSdk = oldPackage.getTargetSdkVersion() < Build.VERSION_CODES.Q
&& newPackage.getTargetSdkVersion() >= Build.VERSION_CODES.Q;
boolean newlyRequestsLegacy = !upgradedSdk && !oldPackage.isRequestLegacyExternalStorage()
&& newPackage.isRequestLegacyExternalStorage();
if (!newlyRequestsLegacy && !downgradedSdk) {
return;
}
final int callingUid = Binder.getCallingUid();
final int userId = UserHandle.getUserId(newPackage.getUid());
int numRequestedPermissions = newPackage.getRequestedPermissions().size();
for (int i = 0; i < numRequestedPermissions; i++) {
PermissionInfo permInfo = getPermissionInfo(newPackage.getRequestedPermissions().get(i),
newPackage.getPackageName(), 0);
if (permInfo == null || !STORAGE_PERMISSIONS.contains(permInfo.name)) {
continue;
}
EventLog.writeEvent(0x534e4554, "171430330", newPackage.getUid(),
"Revoking permission " + permInfo.name + " from package "
+ newPackage.getPackageName() + " as either the sdk downgraded "
+ downgradedSdk + " or newly requested legacy full storage "
+ newlyRequestsLegacy);
revokeRuntimePermissionInternal(permInfo.name, newPackage.getPackageName(),
false, callingUid, userId, null, mDefaultPermissionCallback);
}
}
/**
* We might auto-grant permissions if any permission of the group is already granted. Hence if
* the group of a granted permission changes we need to revoke it to avoid having permissions of
@@ -4884,6 +4932,7 @@ public class PermissionManagerService extends IPermissionManager.Stub {
AsyncTask.execute(() -> {
if (hasOldPkg) {
revokeRuntimePermissionsIfGroupChangedInternal(pkg, oldPkg);
revokeStoragePermissionsIfScopeExpandedInternal(pkg, oldPkg);
}
if (hasPermissionDefinitionChanges) {
revokeRuntimePermissionsIfPermissionDefinitionChangedInternal(