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From: Richard Weinberger <richard@nod.at>
To: Florian Westphal <fw@strlen.de>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Pablo Neira Ayuso <pablo@netfilter.org>,
	David Miller <davem@davemloft.net>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	David Gstir <david@sigma-star.at>,
	kaber@trash.net, "keescook@chromium.org" <keescook@chromium.org>
Subject: Re: nf_conntrack: Infoleak via CTA_ID and CTA_EXPECT_ID
Date: Wed, 12 Jul 2017 23:26:35 +0200	[thread overview]
Message-ID: <1daf1401-5009-df1c-a77a-a271811c0760@nod.at> (raw)
In-Reply-To: <20170701103504.GO9307@breakpoint.cc>

Florian,

Am 01.07.2017 um 12:35 schrieb Florian Westphal:
>>> Perhaps we can place that in a new extension (its not needed in any
>>> fastpath ops)?
>>
>> To get rid of the infoleak we have to re-introduce the id field in struct nf_conn
>> and struct nf_conntrack_expect.
> 
> Why will this not work?

You are right, when we compute the ID from the whole object, it should be fine.

>> Otherwise have nothing to compare against in the conntrack/expect remove case.
> 
> Not following, sorry.  The id is not used anywhere except when we send
> info to userspace.
> 
> The compare on removal is not needed afaics, and its also not used when
> doing lookup to begin with, so we can just recompute it?

Isn't this a way too much overhead?

I personally favor Pablo's per-cpu counter approach.
That way the IDs are unique again and we get rid of the info leak without
much effort.

Thanks,
//richard

  reply	other threads:[~2017-07-12 21:26 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-30 19:25 nf_conntrack: Infoleak via CTA_ID and CTA_EXPECT_ID Richard Weinberger
2017-06-30 19:35 ` Florian Westphal
2017-06-30 19:45   ` Richard Weinberger
2017-06-30 19:55     ` Florian Westphal
2017-06-30 20:23       ` Richard Weinberger
2017-07-01  9:44         ` Pablo Neira Ayuso
2017-07-01 10:35         ` Florian Westphal
2017-07-12 21:26           ` Richard Weinberger [this message]
2017-07-12 22:19             ` Florian Westphal

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