From: "Laura García Liébana" <nevola@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Lukas Wunner <lukas@wunner.de>,
John Fastabend <john.fastabend@gmail.com>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
Florian Westphal <fw@strlen.de>,
Netfilter Development Mailing list
<netfilter-devel@vger.kernel.org>,
coreteam@netfilter.org, netdev@vger.kernel.org,
Alexei Starovoitov <ast@kernel.org>,
Eric Dumazet <edumazet@google.com>, Thomas Graf <tgraf@suug.ch>,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH nf-next v3 3/3] netfilter: Introduce egress hook
Date: Sat, 5 Sep 2020 13:18:37 +0200 [thread overview]
Message-ID: <CAF90-WhWpiAPcpU81P3cPTUmRD-xGkuZ9GZA8Q3cPN7RQKhXeA@mail.gmail.com> (raw)
In-Reply-To: <813edf35-6fcf-c569-aab7-4da654546d9d@iogearbox.net>
Hi Daniel,
On Fri, Sep 4, 2020 at 11:14 PM Daniel Borkmann <daniel@iogearbox.net> wrote:
>
[...]
>
> Its trivial to achieve with tc/BPF on the existing egress hook today. Probably
> takes less time than to write up this mail ...
>
> root@x:~/x# cat foo.c
>
> #include <linux/bpf.h>
> #include <linux/if_ether.h>
> #include <arpa/inet.h>
>
> #ifndef __section
> # define __section(NAME) \
> __attribute__((section(NAME), used))
> #endif
>
> #define ETH_P_KUNBUSGW 0x419C
>
> #define PASS 0
> #define DROP 2
>
> int foo(struct __sk_buff *skb)
> {
> void *data_end = (void *)(long)skb->data_end;
> void *data = (void *)(long)skb->data;
> struct ethhdr *eth = data;
>
> if (data + sizeof(*eth) > data_end)
> return DROP;
>
> return eth->h_proto == htons(ETH_P_KUNBUSGW) ? PASS : DROP;
> }
>
> char __license[] __section("license") = "";
>
> root@x:~/x# clang -target bpf -Wall -O2 -c foo.c -o foo.o
> root@x:~/x# ip link add dev foo type dummy
> root@x:~/x# ip link set up dev foo
> root@x:~/x# tc qdisc add dev foo clsact
> root@x:~/x# tc filter add dev foo egress bpf da obj foo.o sec .text
>
> There we go, attached to the device on existing egress. Double checking it
> does what we want:
>
> root@x:~/x# cat foo.t
> {
> 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
> 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb,
> 0x41, 0x9c
> }
> root@x:~/x# trafgen -i foo.t -o foo -n 1 -q
> root@x:~/x# tcpdump -i foo
> [...]
> 22:43:42.981112 bb:bb:bb:bb:bb:bb (oui Unknown) > aa:aa:aa:aa:aa:aa (oui Unknown), ethertype Unknown (0x419c), length 14:
>
> root@x:~/x# cat bar.t
> {
> 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
> 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb,
> 0xee, 0xee
> }
> root@x:~/x# trafgen -i bar.t -o foo -n 1 -q
> root@x:~/x# tcpdump -i foo
> [... nothing/filtered ...]
>
Something like this seems more trivial to me:
table netdev mytable {
chain mychain {
type filter hook egress device "eth0" priority 100; policy drop;
meta protocol != 0x419C accept
}
}
Cheers.
next prev parent reply other threads:[~2020-09-05 11:23 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 8:55 [PATCH nf-next v3 0/3] Netfilter egress hook Lukas Wunner
2020-08-27 8:55 ` [PATCH nf-next v3 1/3] netfilter: Rename ingress hook include file Lukas Wunner
2020-08-27 8:55 ` [PATCH nf-next v3 2/3] netfilter: Generalize ingress hook Lukas Wunner
2020-08-27 8:55 ` [PATCH nf-next v3 3/3] netfilter: Introduce egress hook Lukas Wunner
2020-08-28 18:52 ` John Fastabend
2020-09-03 5:00 ` John Fastabend
2020-09-04 8:54 ` Laura García Liébana
2020-09-04 15:46 ` John Fastabend
2020-09-05 11:13 ` Laura García Liébana
2020-09-04 16:21 ` Lukas Wunner
2020-09-04 21:14 ` Daniel Borkmann
2020-09-05 5:24 ` Lukas Wunner
2020-09-08 12:55 ` Daniel Borkmann
2020-09-11 7:42 ` Laura García Liébana
2020-09-11 16:27 ` Daniel Borkmann
2020-09-14 11:29 ` Laura García Liébana
2020-09-14 22:02 ` Daniel Borkmann
2020-09-17 10:28 ` Laura García Liébana
2020-09-18 20:31 ` Daniel Borkmann
2020-09-19 15:52 ` Pablo Neira Ayuso
2020-09-21 7:07 ` Laura García Liébana
2020-10-11 8:26 ` Lukas Wunner
2020-11-21 18:59 ` Pablo Neira Ayuso
2020-11-22 3:24 ` Alexei Starovoitov
2020-11-22 11:01 ` Pablo Neira Ayuso
2020-11-24 3:34 ` Alexei Starovoitov
2020-11-24 7:31 ` Lukas Wunner
2020-11-24 22:55 ` Alexei Starovoitov
2020-10-11 7:59 ` Lukas Wunner
2020-09-05 11:18 ` Laura García Liébana [this message]
2020-09-07 22:11 ` Daniel Borkmann
2020-09-08 6:19 ` Laura García Liébana
2020-09-08 11:46 ` Arturo Borrero Gonzalez
2020-09-08 13:27 ` Daniel Borkmann
2020-09-08 18:58 ` John Fastabend
2020-09-19 15:54 ` Pablo Neira Ayuso
2020-09-28 12:20 ` Lukas Wunner
2020-08-27 10:36 ` [PATCH nf-next v3 0/3] Netfilter " Laura García Liébana
2020-08-28 7:14 ` Daniel Borkmann
2020-08-28 9:14 ` Eric Dumazet
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