RFR 9: JEP 290: Filter Incoming Serialization Data
Roger.Riggs at Oracle.com
Mon Jul 25 18:55:15 UTC 2016
Thanks for the review and comments,
Updates in place:
On 7/25/2016 10:54 AM, Chris Hegarty wrote:
> Mainly looks good. Some comments on the spec:
> - Use the Present Simple Tense consistently, e.g.
> "Return*S* an ObjectInputFilter computed from a string of patterns."
> - ObjectInputFilter. Was there a comment already on the use of links?
> For example the following is showing in the javadoc:
> when "setObjectInputFilter" would be better.
ok, will fix (It would be nice if javadoc had a @linksimple that didn't
supply the whole signature).
> Same comment applies to the links to ObjectInputFilter.Status, and
> other places.
> - ObjectInputFilter class description. "If set on an
> ObjectInputStream, the method*(s)* are called ..."
> - Looking at the example in the ObjectInputFilter class description
> makes me think that maybe the default process-wide filter should
> be a filter that simply returns UNDECIDED, rather than being null.
> Is it important to discern whether, or not, it has been set?
When writing a customized filter, it is useful to know whether the
process-wide filter is has been configured.
Usually it is not and there will be a (slight) performance improvement
in not calling it and checking the return.
> - ObjectInputFilter.Config
> The initial sentence in the class description should describe the
> class itself, so maybe " A utility class for ..."
> - "process-wide" is this an agreed upon term? I'm just curious where
> it came from. Is there a more common term for this?
It is useful to distinguish between the filter applied by default to all
one set for a particular stream. I initially used 'global' but that
seemed overly broad.
The description is used sparingly but I'm open to suggestions.
> - Config.setSerialFilter: SecurityException - if there is security
> manager and the SerializablePermission("serialFilter") is not
> granted or if there is no securityManager set and the process-wide
> filter has already been set non-null
> It is a little odd to throw a SE if there is no SM, no ?
True, that would be better as IllegalStateException; updated
> - Is there a class/package level statement covering null, or should
> it be covered for each applicable method?
> - ObjectInputStream
> "... the serialization filter for the stream." ->
> "... the serialization filter for THIS stream."
> - setObjectInputFilter: "The checkInput method is called for each
> class and reference in the stream". Does this apply to back
> references too?
yes, a reference in the stream, as opposed to a new instance in the stream,
refers to back references.
> - setObjectInputFilter: "... when the ObjectInputStream is constructed
> and CANNOT be re-set until an object has been deserialized."
The intent was to prevent it from being modified during deserialization.
But I think it will be clearer if it can only be set non-null once and
only if the previous
value was the pre-configured process-wide filter.
I've also had the recommendation that ObjectInputStream.setObjectInputFilter
should be protected by the same permission as configuring the
> On 19/07/16 15:02, Roger Riggs wrote:
>> Please review the design, implementation, and tests of JEP 290: Filter
>> Incoming Serialization Data
>> It allows incoming streams of object-serialization data to be filtered
>> in order to improve both security and robustness.
>> The JEP has more detail on the background and scope.
>> The core mechanism is a filter interface implemented by serialization
>> clients and set on an |ObjectInputStream|. The filter is called during
>> the deserialization process to validate the classes being deserialized,
>> the sizes of arrays being created, and metrics describing stream length,
>> stream depth, and number of references as the stream is being decoded.
>> A process-wide filter can be configured that is applied to every
>> The API of ObjectInputStream can be used to set a custom filter to
>> supersede or augment the process-wide filter.
>> Javadoc (subset)
>> Comments appreciated, Roger
>>  JEP 290: https://bugs.openjdk.java.net/browse/JDK-8154961
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