From: Eric Dumazet <eric.dumazet@gmail.com>
To: Amit Salecha <amit.salecha@qlogic.com>
Cc: David Miller <davem@davemloft.net>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Ameen Rahman <ameen.rahman@qlogic.com>,
Anirban Chakraborty <anirban.chakraborty@qlogic.com>
Subject: RE: [PATCH] qlcnic: dont assume NET_IP_ALIGN is 2
Date: Tue, 21 Sep 2010 10:34:33 +0200 [thread overview]
Message-ID: <1285058073.2617.73.camel@edumazet-laptop> (raw)
In-Reply-To: <99737F4847ED0A48AECC9F4A1974A4B80F86F80270@MNEXMB2.qlogic.org>
Le mardi 21 septembre 2010 à 03:19 -0500, Amit Salecha a écrit :
>
> > -----Original Message-----
> > From: David Miller [mailto:davem@davemloft.net]
> > Sent: Monday, September 20, 2010 9:29 PM
> > To: Amit Salecha
> > Cc: eric.dumazet@gmail.com; netdev@vger.kernel.org; Ameen Rahman;
> > Anirban Chakraborty
> > Subject: Re: [PATCH] qlcnic: dont assume NET_IP_ALIGN is 2
> >
> > From: Amit Salecha <amit.salecha@qlogic.com>
> > Date: Mon, 20 Sep 2010 06:16:31 -0500
> >
> > > Though I have one doubt. We are allocating larger packets than the
> > actual data used.
> > > Doesn't it will break accounting ?
> >
> > No, it will "fix" accounting.
> >
> > You must charge to the SKB all of the non-shared memory that was
> > allocated to the SKB.
> >
> > This means even if the packet only uses 128 bytes of the SKB
> > data area, you must still account for the full blob of linear
> > memory that was allocated for the SKB data area in skb->truesize.
> >
> > Otherwise remote attackers could consume enormous amounts of memory by
> > tricking our socket accounting via carefully sized packets.
>
> Wont this affect throughput ?
> As problem discuss in this thread http://www.mail-archive.com/netdev@vger.kernel.org/msg06848.html, it can affect tcp window scaling.
>
Amit, if you believe this is a problem, you should address it for all
NICS, not only qlcnic.
Qlcnic was lying to stack, because it consumed 2Kbytes blocs and
pretended they were consuming skb->len bytes.
(assuming MTU=1500, problem is worse if MTU is bigger)
So in order to improve "throughput", you were allowing for memory
exhaust and freeze of the _machine_ ?
next prev parent reply other threads:[~2010-09-21 8:34 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-17 5:14 [PATCHv2 NEXT 0/5]qlcnic: vlan rx accleration support Amit Kumar Salecha
2010-09-17 5:14 ` [PATCHv2 NEXT 1/5] qlcnic: support vlan rx accleration Amit Kumar Salecha
2010-09-17 5:29 ` Eric Dumazet
2010-09-17 9:57 ` [PATCH] qlcnic: dont assume NET_IP_ALIGN is 2 Eric Dumazet
2010-09-17 10:53 ` Amit Salecha
2010-09-18 5:58 ` David Miller
2010-09-20 11:16 ` Amit Salecha
2010-09-20 12:18 ` Eric Dumazet
2010-09-20 12:28 ` [PATCH net-next-2.6] qlnic: dont set skb->truesize Eric Dumazet
2010-09-20 17:09 ` David Miller
2010-09-20 15:58 ` [PATCH] qlcnic: dont assume NET_IP_ALIGN is 2 David Miller
2010-09-21 8:19 ` Amit Salecha
2010-09-21 8:34 ` Eric Dumazet [this message]
2010-09-21 8:41 ` Amit Salecha
2010-09-21 9:23 ` Eric Dumazet
2010-09-21 19:33 ` David Miller
2010-09-21 19:55 ` [PATCH] netxen: dont set skb->truesize Eric Dumazet
2010-09-21 20:04 ` David Miller
2010-09-17 5:14 ` [PATCHv2 NEXT 2/5] qlcnic: vlan gro support Amit Kumar Salecha
2010-09-17 18:24 ` David Miller
2010-09-17 18:25 ` David Miller
2010-09-17 5:14 ` [PATCHv2 NEXT 3/5] qlcnic: vlan lro support Amit Kumar Salecha
2010-09-17 5:14 ` [PATCHv2 NEXT 4/5] qlcnic: remove fw version check Amit Kumar Salecha
2010-09-17 5:14 ` [PATCHv2 NEXT 5/5] qlcnic: update version 5.0.10 Amit Kumar Salecha
2010-09-17 18:31 ` [PATCHv2 NEXT 0/5]qlcnic: vlan rx accleration support David Miller
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