High memory usage / leaks was: Best mailing list for JVM embedding
robert at marcanoonline.com
Fri Jan 25 12:34:34 UTC 2019
On 1/24/19 11:05 AM, Sean Mullan wrote:
> On 1/24/19 8:25 AM, Robert Marcano wrote:
>> On 1/23/19 8:59 AM, Sean Mullan wrote:
>>> On 1/22/19 8:50 PM, Bernd Eckenfels wrote:
>>>> I don’t think the launcher is doing this, it is the class loader,
>>>> that’s nothing new. You can turn on verbose security debug to see it
>>>> in all versions.
>>> Yes, and it only verifies the signature(s) on the JAR. It doesn't
>>> validate the certificate chain.
>> I noticed that trying to identify the higher memory usage after what
>> looks like a big application is loaded. I am doing memory profiling
>> and notice JarFile taking more memory that on Java 8. Still need to
>> detect the real cause for an independent test case. We probably didn't
>> notice this slowdown before because Oracle's JNLP implementation was
>> slow enough at startup.
>> IMHO the class library should not do doing signature checks without
>> certificate validation, because it doesn't give any protection if the
>> signature is not verified, the only thing it could do now is to detect
>> some random bit flips, that maybe the Zip format CRC detect before
>> that. With no certificate verification the signature could be replaced
>> by anybody with bad intentions.
> It's a fair point, although since URLClassLoader is a subclass of
> SecureClassLoader the certificate chain does get populated into the
> CodeSource of the classes loaded, so one could potentially write a
> custom ClassLoader or additional code to additionally validate the
> certificate chain. Also, keep in mind that validating a certificate
> chain for signed code is not usually sufficient to determine if you
> actually trust who signed the code; some additional policy configuration
> (or UI prompts) are usually required. Also, if you run the application
> with a SecurityManager you can grant the signed JARs additional
> permissions based on who signed the code in an associated policy file,
> see  for more info.
Thanks for the info, but this is for corporate intranet application
distribution of an ISV (us) application, no untrusted code installation.
We are signing our code with a certificate from a private CA and the CA
is embedded on the native updater/launcher as the exclusive CA used for
dowloaded updates validation. It is more like the Firefox/Chrome updater.
>> Maybe adding a constructor flag to URLClassloader to pass to JarFile
>> to skip verification and a system property to tell the Java startup
>> code to skip verification of java.class.path (just for compatibility
>> with old code that expect it to be done). There is precedent of other
>> runtimes that added options to disable this, like CLR  (Ii not only
>> verified signatures, It do CRL/OSCP checks too)
> It's easy enough to strip signatures from JAR files (which you mention
> below). So if this is really an issue, I would be more inclined to just
> do that if it is an option.
Yea, I added an option to remove the signatures from the downloaded
updates (after signature validation) so they are not validated anymore
at launch time.
>> Our new launcher replacing JNLP now do signature verification in
>> native code, at download time, and install on a system area (not user
>> home directory), so signature verification at application launch is a
>> slowdown we want to avoid, but think on another kind of users, those
>> deploying to OS Stores (for example Windows Store), why add the
>> slowdown of verification when the application is verified by the store
>> client at install time?, this could help these situations too.
>> Note: This can be avoided removing the signatures of all JARs if you
>> distribute to an OS store, there are a few libraries that distribute
>> their JARs signed (The old Java Help framework comes to my mind right
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