[wildfly-dev] my 2 cents on Security Manager discussion

[Jason Greene]

Right. An operating system is able to segment code by using page mapping and traps. Each process gets a dedicated memory area that another process can’t access at a very low level (without special permissions). The JVM + SM on the other hand relies on protection at a higher level. Fundamentally the entire JVM memory area is shared between all code. The only thing that prevents it is lots of security checks on every possible method that might leak a reference. So the fundamental flaw is that the SM requires a perfect policy, and is essentially trust-by-default. If a developer forgets to add a check, then a vulnerability is possible. This happens frequently, even in the JDK itself (hence the multiple CVEs)

The only way the JVM could fix this, is if it introduced real multi-tenancy at the lowest levels. You would have to operate similar to an OS and assign blocks of heap to a particular app, and allow sharing for certain “safe” things like code pages tied to class implementations. 

On Apr 23, 2014, at 8:38 AM, Bill Burke <bburke at redhat.com> wrote:

> As much as we like to think the app server is an operating system, it 
> isn't.  The app server isn't a place where untrusted apps run.
> 
> On 4/23/2014 8:40 AM, Josef Cacek wrote:
>> Hi Arjan,
>> 
>> let me give you few examples. Do you really want to allow users/deployed-apps/3rd-party-libs
>> 
>>  * call System.exit()?
>>  * change behavior of the whole JVM by changing some system properties (keystores and truststores for instance)?
>>  * use reflection to read/change private data (caches, etc)?
>>  * access the filesystem (e.g. rewrite the WildFly configuration files)?
>>  * ...
>> 
>> If the answer is always yes, then you don't need the JSM I think.
>> 
>> But if you care what can do the parts of code which you don't have under full control, then you should really use the Java Security Manager.
>> 
>> Best regards,
>> 
>> -- Josef
>> 
>> ----- Original Message -----
>>> From: "arjan tijms" <arjan.tijms at gmail.com>
>>> To: "Jason T. Greene" <jgreene at redhat.com>
>>> Cc: wildfly-dev at lists.jboss.org
>>> Sent: Saturday, April 19, 2014 7:43:24 PM
>>> Subject: Re: [wildfly-dev] my 2 cents on Security Manager discussion
>>> 
>>> Hi,
>>> 
>>> Just wondering, but what is the primary use case for a security manager
>>> server side?
>>> 
>>> While the model obviously makes sense for Applets and Webstart where
>>> untrusted code is executed on the user's machine, I found it to be extremely
>>> rare for a server to run untrusted code. In fact, I don't think I've ever
>>> seen this situation.
>>> 
>>> There's maybe a case to prevent privilege escalation in case of a legitimate
>>> app being hacked, but in practice it doesn't look like a security manager is
>>> really being used a lot for that, is it? Instead the default thing to do
>>> there seems to be to run the AS under a user with limited rights on the host
>>> OS and/or use things like SELinix or Virtual Servers (e.g. XEN) to isolate
>>> the complete AS.
>>> 
>>> Kind regards,
>>> Arjan Tijms
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> 
> -- 
> Bill Burke
> JBoss, a division of Red Hat
> http://bill.burkecentral.com
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--
Jason T. Greene
WildFly Lead / JBoss EAP Platform Architect
JBoss, a division of Red Hat