netdev - Re: [PATCH net-next] ebpf, filter: do not convert skb->protocol to host endianess during runtime

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: <550B1A91.6030502@plumgrid.com>
Date:	Thu, 19 Mar 2015 11:50:57 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Daniel Borkmann <daniel@...earbox.net>, davem@...emloft.net
CC:	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] ebpf, filter: do not convert skb->protocol to
 host endianess during runtime

On 3/19/15 11:38 AM, Daniel Borkmann wrote:
> Commit c24973957975 ("bpf: allow BPF programs access 'protocol' and 'vlan_tci'
> fields") has added support for accessing protocol, vlan_present and vlan_tci
> into the skb offset map.
>
> As referenced in the below discussion, accessing skb->protocol from an eBPF
> program should be converted without handling endianess.
>
> The reason for this is that an eBPF program could simply do a check more
> naturally, by f.e. testing skb->protocol == htons(ETH_P_IP), where the LLVM
> compiler resolves htons() against a constant automatically during compilation
> time, as opposed to an otherwise needed run time conversion.
>
> After all, the way of programming both from a user perspective differs quite
> a lot, i.e. bpf_asm ["ld proto"] versus a C subset/LLVM.
>
> Reference: https://patchwork.ozlabs.org/patch/450819/
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> ---
>   (Follow-up from our previous discussion)

sure. let's save few run-time cycles.

Acked-by: Alexei Starovoitov <ast@...mgrid.com>

--
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