Re: [RFC 0/0] Introducing a generic socket offload framework

[San Mehat]

On Fri, Aug 19, 2011 at 5:49 AM, jamal <hadi@xxxxxxxxxx> wrote:
>
> On Thu, 2011-08-18 at 15:07 -0700, San Mehat wrote:
> > TL;DR
> > -----
> > In this RFC we propose the introduction of the concept of hardware socket
> > offload to the Linux kernel. Patches will accompany this RFC in a few days,
> > but we felt we had enough on the design to solicit constructive discussion
> > from the community at-large.
> >
>
> [..]
>
> > ALTERNATIVE STRATEGIES
> > ----------------------
> >
> > An alternative strategy for providing similar functionality involves either
> > modifying glibc or using LD_PRELOAD tricks to intercept socket calls. We were
> > forced to rule this out due to the complexity (and fragility) involved with
> > attempting to maintain a general solution compatible across various
> > distributions where platform-libraries differ.
>
> Above should have been in your TL;DR;->
>
> LD_PRELOAD is also horrible because of the granularity of the socket
> calls;
> Having things in the kernel and specifically tagging socket as needing
> this feature is much much more manageable.
>
> Tying things to virtualization may miss the big picture because there
> are many other use cases for intercepting socket calls, example:
> Samir Bellabes <sam@xxxxxxxxx> has been trying to get what he refers to
> as "personal firewall" (equivalent to the silly windows firewall) which
> prompts the user "ping from blah, do you want to allow a response?"
> That requires intercepting send/recv calls, prompt the user in possibly
> some pop-up and act based on response. It requires looking at content.
> He is trying to use selinux for that interface,
> but i think this would be the right abstraction.

I agree; there's no reason this needs to be tied to virtualization -
it was just the
driving force behind the design. I will generalize the backend interface types

> I hope you plan to support send/recv.

yes

> I also hope you add support for SOCK_RAW (and maybe SOCK_PACKET).

Can you explain a good use-case for SOCK_RAW in this type of
environment? We were noodling it around locally and couldn't come up
with one that we needed to support.

>
> Q: If you want this to be transparent to the apps, who/what is doing
> the tagging of SOCK_HWASSIST? clearly not the app if you dont want to
> change it.

The decision of whether to tag a socket or not is made by the 'hardware'

>
> I like the uri abstraction if it doesnt come at the expense of the
> app transparency.
>

Thank you

-san

> cheers,
> jamal
>



--
San Mehat | Staff Software Engineer | san@xxxxxxxxxx | 415-366-6172
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