lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Tue, 25 Nov 2014 20:01:13 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	alexander.duyck@...il.com, alexander.h.duyck@...hat.com,
	netdev@...r.kernel.org, jeffrey.t.kirsher@...el.com
Subject: Re: [net-next PATCH 2/5] ethernet/intel: Use eth_skb_pad helper

On Tue, 2014-11-25 at 22:19 -0500, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Tue, 25 Nov 2014 17:43:05 -0800
> 
> > I believe I finally have an idea why we had various + 15 in skb
> > allocations in TCP stack !
> 
> It was so that you could do one level of tunneling with "for
> free".  Or that is my recollection.
> 
> Those + 15 existed way before any of these padto() calls even
> existed.


Well, tunneling is added in front of the packet. Thats why we use
MAX_TCP_HEADER.

The +15 is in fact because TCP stack wanted to make sure the eventual
padding (needing tailroom, not headroom) was possible...

Note that ack packets never used the +15, but other packets did.


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists