netdev - Question about more headroom in skb

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-next>] [day] [month] [year] [list]

Message-ID: <682359.68270.qm@web112510.mail.gq1.yahoo.com>
Date:	Mon, 10 May 2010 13:09:27 -0700 (PDT)
From:	Sharat Masetty <sharat_masetty@...oo.com>
To:	netdev@...r.kernel.org
Subject: Question about more headroom in skb

Hello All,

For my project I need 3 words of headroom in the skb in the network driver level, to add a  custom header to the ethernet packet. I looked into the tcp code and figured out tcp uses sk->sk_prot->max_header for header allocation size. But I was not able to confirm that all other transport protocol use the same mechanism(?) For example in UDP/ICMP I was not able to figure out from the code where the allocation and header reservation happens(Any light here would be really helpful.)

I have also looked at an API in skbuff skb_pad() which does what I want(add either headroom or tailroom), but I want to avoid that for performance reasons(skb_pad does kmalloc and memcpy). I want to figure out a good way(may be tune some parameters) to allocate extra 3 words for any skbuff independant of the transport protocol being used. Any light here would be very much appreciated.

Thanks,
Sharat.

--
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