netdev - Re: [PATCH v2 net-next 1/2] bpf: make programs see skb->data == L2 for ingress and egress

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: <557173E3.5020807@mojatatu.com>
Date:	Fri, 05 Jun 2015 06:03:15 -0400
From:	Jamal Hadi Salim <jhs@...atatu.com>
To:	Alexei Starovoitov <ast@...mgrid.com>,
	"David S. Miller" <davem@...emloft.net>
CC:	Eric Dumazet <edumazet@...gle.com>,
	Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org
Subject: Re: [PATCH v2 net-next 1/2] bpf: make programs see skb->data == L2
 for ingress and egress

On 06/04/15 13:11, Alexei Starovoitov wrote:
> eBPF programs attached to ingress and egress qdiscs see inconsistent skb->data.
> For ingress L2 header is already pulled, whereas for egress it's present.
> This is known to program writers which are currently forced to use
> BPF_LL_OFF workaround.
> Since programs don't change skb internal pointers it is safe to do
> pull/push right around invocation of the program and earlier taps and
> later pt->func() will not be affected.
> Multiple taps via packet_rcv(), tpacket_rcv() are doing the same trick
> around run_filter/BPF_PROG_RUN even if skb_shared.
>
> This fix finally allows programs to use optimized LD_ABS/IND instructions
> without BPF_LL_OFF for higher performance.
> tc ingress + cls_bpf + samples/bpf/tcbpf1_kern.o
>         w/o JIT   w/JIT
> before  20.5     23.6 Mpps
> after   21.8     26.6 Mpps
>
> Old programs with BPF_LL_OFF will still work as-is.
>
> We can now undo most of the earlier workaround commit:
> a166151cbe33 ("bpf: fix bpf helpers to use skb->mac_header relative offsets")
>
> Signed-off-by: Alexei Starovoitov <ast@...mgrid.com>
> ---

Acked-by: Jamal Hadi Salim <jhs@...atatu.com>

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