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Re: Firewall rules using SELinux context (Was Re: RFE: FireKit)



On 07/24/2009 03:53 PM, Stephen Smalley wrote:
> On Fri, 2009-07-24 at 15:47 -0400, Casey Dahlin wrote:
>> A couple of mentions of SELinux have cropped up in the FireKit thread, which got me thinking about the Firewall and SELinux and ways in which they are similar. I had the following thought:
>>
>> SELinux already has a lot of policy information from which we might like to determine whether ports should be open to a particular program. The simplest mechanism I can see for doing that is to allow SELinux context to be referenced in the firewall rules. This prevents either system from having to be grotesquely modified.
>>
>> An example rule might look like this:
>>
>> -A INPUT -Z apache_t -j ACCEPT
>>
>> Here we tell the firewall to allow incoming traffic that will be intercepted in userspace by a process in the apache_t context.
>>
>> This does break in at least one way from traditional SELinux policy: something external to SELinux is interpreting the meaning of the context. The firewall rules can change while the actual SELinux policy stays put. I don't know how serious a problem that is (if it is one).
>>
>> Thoughts?
> 
> SECMARK already allows you to label packets using iptables and then use
> SELinux policy to control sending or receiving them.
> 
> http://paulmoore.livejournal.com/4281.html
> 
> There are also the name_connect and name_bind controls that regulate the
> ability to connect or bind to specific ports via policy.
> 

This is a very different mechanism. The idea behind my proposal is it allows a packet to be routed based on who is going to receive it. SECMARK, it seems, is designed to control who receives a packet based on how it is being routed. I don't know if you get the same effect this way.

--CJD


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