netdev - Re: [PATCH v3 net-next 2/2] tc: add 'needs

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]

Message-ID: <55265C5C.7020200@mojatatu.com>
Date:	Thu, 09 Apr 2015 07:02:52 -0400
From:	Jamal Hadi Salim <jhs@...atatu.com>
To:	Alexei Starovoitov <ast@...mgrid.com>,
	David Miller <davem@...emloft.net>
CC:	daniel@...earbox.net, tgraf@...g.ch, jiri@...nulli.us,
	netdev@...r.kernel.org
Subject: Re: [PATCH v3 net-next 2/2] tc: add 'needs_l2' flag to ingress qdisc

On 04/09/15 06:49, Jamal Hadi Salim wrote:
> On 04/08/15 23:05, Alexei Starovoitov wrote:
> [..]
>> As I said I'd rather disable them attaching to ingress than force
>> all program authors to always use network_offset.
>> Offset 0 points to L2 was always fundamental assumption of BPF.
>
> The issue is not really the ingress qdisc here - rather the ingress
> qdisc tries to cope with _how things work_.
> The challenge is *some netdevs* (not all) strip off the link
> layer _before_ the ingres qdisc sees them. You have to recognize
> those devices and only speacial case with them. Your assumptions of
> blindly pushing/pulling will break  in some cases (take a look at
> mirred).
>

To be precise look at:
tcf_mirred_init() and how ok_push based on dev->type is decided.
So we do this in the slow path and make a simple compare in the
fast path on whether push the l2 header.

cheers,
jamal
--
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