From: Thomas Graf <tgraf@suug.ch>
To: Tom Herbert <tom@herbertland.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
roopa <roopa@cumulusnetworks.com>
Subject: Re: [PATCH net-next 3/4] bpf: BPF for lightweight tunnel encapsulation
Date: Mon, 31 Oct 2016 16:06:40 +0100 [thread overview]
Message-ID: <20161031150640.GC32374@pox.localdomain> (raw)
In-Reply-To: <CALx6S34hHZDdtZgLBZzw-QiOc80tjrLAuAVBDeWRuUonR1MfXA@mail.gmail.com>
On 10/31/16 at 07:17am, Tom Herbert wrote:
> On Mon, Oct 31, 2016 at 5:59 AM, Thomas Graf <tgraf@suug.ch> wrote:
> > Noticed while implementing this: How does ILA ensure that dst_output()
> > is not invoked in a circular manner?
> >
> > dstA->output() -> dstB->otuput() -> dstA->output() -> ...
>
> It doesn't. We'll need to add a check for that. Maybe the rule should
> be that an skbuff is only allowed to hit one LWT route?
I'll add a per cpu variable to do a recursion limit for dst_output()
which callers to possibly recurse can use. ILA can use that as well.
> Another scenario to consider: Suppose someone is doing protocol
> translation like in RFC7915. This is one of operations we'd need with
> ILA or GRE to implement an IPv4 overlay network over IPv6. Would this
> be allowed/supported in LWT BPF?
In lwtunnel_xmit() yes, input and output would not support this right
now. It will need some logic as the orig_input and orig_output would
obviously be expecting the same protocol. This is the reason why the
xmit prog type currently has a wider set of allowed helpers.
next prev parent reply other threads:[~2016-10-31 15:06 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-30 11:58 [PATCH net-next 0/4] BPF for lightweight tunnel encapsulation Thomas Graf
2016-10-30 11:58 ` [PATCH net-next 1/4] route: Set orig_output when redirecting to lwt on locally generated traffic Thomas Graf
2016-10-30 11:58 ` [PATCH net-next 2/4] route: Set lwtstate for local traffic and cached input dsts Thomas Graf
2016-10-30 11:58 ` [PATCH net-next 3/4] bpf: BPF for lightweight tunnel encapsulation Thomas Graf
2016-10-30 20:34 ` Tom Herbert
2016-10-30 21:47 ` Thomas Graf
2016-10-31 1:28 ` Tom Herbert
2016-10-31 8:19 ` Thomas Graf
2016-10-31 12:59 ` Thomas Graf
2016-10-31 14:17 ` Tom Herbert
2016-10-31 15:06 ` Thomas Graf [this message]
2016-10-31 16:07 ` Tom Herbert
2016-10-31 17:35 ` Thomas Graf
2016-10-30 11:58 ` [PATCH net-next 4/4] bpf: Add samples for LWT-BPF Thomas Graf
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