netdev - Re: [af-packet 1/2] Enhance af-packet to provide (near zero)lossless packet capture functionality.

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Message-ID: <BANLkTi=_EFRaiPuT=OjwRaJ4XPw0sUhcnA@mail.gmail.com>
Date:	Wed, 8 Jun 2011 18:10:02 -0400
From:	chetan loke <loke.chetan@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, kaber@...sh.net,
	johann.baudy@...-log.net, Chetan Loke <lokec@....neu.edu>
Subject: Re: [af-packet 1/2] Enhance af-packet to provide (near zero)lossless
 packet capture functionality.

On Wed, Jun 8, 2011 at 12:35 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le mardi 07 juin 2011 à 23:13 -0400, Chetan Loke a écrit :
>>
>> +struct tpacket3_hdr {
>> +     __u32           tp_status;
>> +     __u32           tp_len;
>> +     __u32           tp_snaplen;
>> +     __u16           tp_mac;
>> +     __u16           tp_net;
>
>> +     __u32           tp_sec;
>> +     __u32           tp_nsec;
>> +     __u16           tp_vlan_tci;
>
> missing "__u16 tp_padding;" here
>
> check :
>
> http://git2.kernel.org/?p=linux/kernel/git/davem/net-2.6.git;a=commit;h=13fcb7bd322164c67926ffe272846d4860196dc6


Eric, thanks for pointing that. I will add the padding. But just out
of curiosity, how is the information being leaked in tpacket_rcv()?

If someone is capturing packets then they have access to all the data
anyways. Also, tpacket_rcv doesn't memset the frame-element to 'zero'
before calling
skb_copy_bits(). And we would never want to memset anyways.

thnx
Chetan Loke
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