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Date: Fri, 01 Jan 2010 03:41:43 -0800
From: ebiederm@...ssion.com (Eric W. Biederman)
To: daw-news@...erner.cs.berkeley.edu (David Wagner)
Cc: linux-kernel@...r.kernel.org
Subject: Re: RFC: disablenetwork facility. (v4)
daw@...berkeley.edu (David Wagner) writes:
> Eric W. Biederman wrote:
>>The problem with the disable_network semantics you want
>>is that they allow you to perform a denial of service attack
>>on privileged users. An unprivileged DOS attack is unsuitable
>>for a general purpose feature in a general purpose kernel.
>
> I'm not persuaded yet.
I won't try hard to persuade you if you drop me off the cc list.
> When you talk about DOS, let's be a bit more precise. disablenetwork
> gives a way to deny setuid programs access to the network. It's not a
> general-purpose DOS; it's denying access to the network only. And the
> network is fundamentally unreliable. No security-critical mechanism
> should be relying upon the availability of the network.
The audit daemon should not rely on netlink?
> So while I certainly can't rule out the possibility that disablenetwork
> might introduce minor issues, I think there are fundamental reasons to
> be skeptical that disablenetwork will introduce serious new security
> problems.
For me the case is simple. I have seen several plausible sounding
scenarios that get most of the way there. I know I am stupid when
it comes to security and that people exploiting problems are going
to be looking harder than I will. Therefore I think there is
a reasonable chance this will introduce a security hole for someone.
Eric
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