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Re: [saag] draft-stjohns-sipso-05 & transport protocols



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Steven M. Bellovin wrote:
> On Fri, 03 Oct 2008 08:30:01 -0700
> Joe Touch <touch at ISI.EDU> wrote:
> 
>> If you follow the implications of " With respect to a given network,
>> each distinct Sensitivity Label represents a separate virtual network
>> which shares the same physical network.", and the way it impacts TCP,
>> can you explain how the current draft indicates how to similarly
>> virtualize any of the following?
>>
>> - - ICMP handling
>> - - forwarding
>> - - routing
>> - - IPv6 neighbor discovery
>> - - IGMP
>> - - PIM
>> - - IPsec
>> - - IPIP tunnels
>> - - firewalls
>>
>> All of these things use IP addresses as unique identifiers, and all
>> are affected by extending that space to use the pair [address,
>> security level] instead.
>>
> Without trying to answer in detail, the basic rule is simple: no data
> with a given security label should eveFrom saag-bounces at ietf.org  Fri Oct  3 09:47:28 2008
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Date: Fri, 03 Oct 2008 09:47:16 -0700
From: Joe Touch <touch at ISI.EDU>
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Cc: draft-stjohns-sipso-05 at tools.ietf.org, TSV Area <tsv-area at ietf.org>,
	saag at ietf.org
Subject: Re: [saag] draft-stjohns-sipso-05 & transport protocols
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Steven M. Bellovin wrote:
> On Fri, 03 Oct 2008 08:30:01 -0700
> Joe Touch <touch at ISI.EDU> wrote:
> 
>> If you follow the implications of " With respect to a given network,
>> each distinct Sensitivity Label represents a separate virtual network
>> which shares the same physical network.", and the way it impacts TCP,
>> can you explain how the current draft indicates how to similarly
>> virtualize any of the following?
>>
>> - - ICMP handling
>> - - forwarding
>> - - routing
>> - - IPv6 neighbor discovery
>> - - IGMP
>> - - PIM
>> - - IPsec
>> - - IPIP tunnels
>> - - firewalls
>>
>> All of these things use IP addresses as unique identifiers, and all
>> are affected by extending that space to use the pair [address,
>> security level] instead.
>>
> Without trying to answer in detail, the basic rule is simple: no data
> with a given security label should ever be senr be sent to or through an entity
> with a different label.  Routers and links are typically multi-label,
> so they can accept data within a range of levels.  A process will
> always be single-level, so it can only accept data -- TCP, ICMP
> replies, etc. -- at exactly the same level.  There are exceptions --
> IPsec boxes would (in that environment) be trusted to downgrade
> information, i.e., accept sensitive data, encrypt it, and send out the
> ciphertext packets with a different label.  IGMP poses a fascinating
> problem; I don't know that anyone has ever worked out the implications
> of doing that in an MLS environment.

Understood; the issue is that this document, if intended to extend MLS
into the architecture of MLS-enabled hosts, needs to be augmented
substantially to address these issues - even if to declare some out of
scope and not supported.

I don't know if it's tenable to assert that only the transport protocols
of interest are virtualized.

Joe
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t to or through an entity
> with a different label.  Routers and links are typically multi-label,
> so they can accept data within a range of levels.  A process will
> always be single-level, so it can only accept data -- TCP, ICMP
> replies, etc. -- at exactly the same level.  There are exceptions --
> IPsec boxes would (in that environment) be trusted to downgrade
> information, i.e., accept sensitive data, encrypt it, and send out the
> ciphertext packets with a different label.  IGMP poses a fascinating
> problem; I don't know that anyone has ever worked out the implications
> of doing that in an MLS environment.

Understood; the issue is that this document, if intended to extend MLS
into the architecture of MLS-enabled hosts, needs to be augmented
substantially to address these issues - even if to declare some out of
scope and not supported.

I don't know if it's tenable to assert that only the transport protocols
of interest are virtualized.

Joe
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