From: David Ahern <dsahern@gmail•com>
To: Daniel Borkmann <daniel@iogearbox•net>,
dsahern@kernel•org, netdev@vger•kernel.org,
borkmann@iogearbox•net, ast@kernel•org
Cc: davem@davemloft•net, kafai@fb•com
Subject: Re: [PATCH v2 bpf-net] bpf: Change bpf_fib_lookup to return lookup status
Date: Tue, 26 Jun 2018 07:53:41 -0600 [thread overview]
Message-ID: <f33d42e4-ec29-bb5a-967e-dbacbd8ec076@gmail.com> (raw)
In-Reply-To: <4cd62659-1b52-6746-5a37-faa01d476476@iogearbox.net>
On 6/26/18 3:50 AM, Daniel Borkmann wrote:
> [...]
> You change all the semantics of return code here, but this breaks bpf_skb_fib_lookup().
> I cannot see how this would work in that case. The code does the following with the
> bpf_ipv{4,6}_fib_lookup() return code:
>
> [...]
> switch (params->family) {
> #if IS_ENABLED(CONFIG_INET)
> case AF_INET:
> index = bpf_ipv4_fib_lookup(net, params, flags, false);
> break;
> #endif
> #if IS_ENABLED(CONFIG_IPV6)
> case AF_INET6:
> index = bpf_ipv6_fib_lookup(net, params, flags, false);
> break;
> #endif
> }
>
> if (index > 0) {
> struct net_device *dev;
>
> dev = dev_get_by_index_rcu(net, index);
> if (!is_skb_forwardable(dev, skb))
> index = 0;
> }
Yes, I forgot to update the skb path. That should be rc now and then the
dev lookup based on params->ifindex. Will fix.
> [...]
>
> So the BPF_FIB_LKUP_* results become the dev ifindex here and the !is_skb_forwardable()
> case further suggests that the packet *can* be forwarded based on the new semantics
> whereas MTU check is bypassed on success.
>
> It probably helps to craft a selftest for XDP *and* tc case in future, so we can be sure
> nothing breaks with new changes.
yes, will do.
prev parent reply other threads:[~2018-06-26 13:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-21 3:00 [PATCH v2 bpf-net] bpf: Change bpf_fib_lookup to return lookup status dsahern
2018-06-21 17:09 ` Martin KaFai Lau
2018-06-22 15:49 ` Jesper Dangaard Brouer
2018-06-26 9:50 ` Daniel Borkmann
2018-06-26 13:53 ` David Ahern [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=f33d42e4-ec29-bb5a-967e-dbacbd8ec076@gmail.com \
--to=dsahern@gmail$(echo .)com \
--cc=ast@kernel$(echo .)org \
--cc=borkmann@iogearbox$(echo .)net \
--cc=daniel@iogearbox$(echo .)net \
--cc=davem@davemloft$(echo .)net \
--cc=dsahern@kernel$(echo .)org \
--cc=kafai@fb$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox