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From: Jakub Sitnicki <jakub@cloudflare.com>
To: Lorenz Bauer <lmb@cloudflare.com>
Cc: Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	dccp@vger.kernel.org, kernel-team <kernel-team@cloudflare.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Gerrit Renker <gerrit@erg.abdn.ac.uk>,
	Jakub Kicinski <kuba@kernel.org>,
	Marek Majkowski <marek@cloudflare.com>
Subject: Re: [PATCH bpf-next 02/17] bpf: Introduce SK_LOOKUP program type with a dedicated attach point
Date: Wed, 06 May 2020 15:53:35 +0200	[thread overview]
Message-ID: <87eerxuq3k.fsf@cloudflare.com> (raw)
In-Reply-To: <CACAyw9-ro_Dit=3M46=JSrkuc8y+UcsvJgVQuG98KdtmM9mCCA@mail.gmail.com>

On Wed, May 06, 2020 at 03:16 PM CEST, Lorenz Bauer wrote:
> On Wed, 6 May 2020 at 13:55, Jakub Sitnicki <jakub@cloudflare.com> wrote:

[...]

>> @@ -4012,4 +4051,18 @@ struct bpf_pidns_info {
>>         __u32 pid;
>>         __u32 tgid;
>>  };
>> +
>> +/* User accessible data for SK_LOOKUP programs. Add new fields at the end. */
>> +struct bpf_sk_lookup {
>> +       __u32 family;           /* AF_INET, AF_INET6 */
>> +       __u32 protocol;         /* IPPROTO_TCP, IPPROTO_UDP */
>> +       /* IP addresses allows 1, 2, and 4 bytes access */
>> +       __u32 src_ip4;
>> +       __u32 src_ip6[4];
>> +       __u32 src_port;         /* network byte order */
>> +       __u32 dst_ip4;
>> +       __u32 dst_ip6[4];
>> +       __u32 dst_port;         /* host byte order */
>
> Jakub and I have discussed this off-list, but we couldn't come to an
> agreement and decided to invite
> your opinion.
>
> I think that dst_port should be in network byte order, since it's one
> less exception to the
> rule to think about when writing BPF programs.
>
> Jakub's argument is that this follows __sk_buff->local_port precedent,
> which is also in host
> byte order.

Yes, would be great to hear if there is a preference here.

Small correction, proposed sk_lookup program doesn't have access to
__sk_buff, so perhaps that case matters less.

bpf_sk_lookup->dst_port, the packet destination port, is in host byte
order so that it can be compared against bpf_sock->src_port, socket
local port, without conversion.

But I also see how it can be a surprise for a BPF user that one field has
a different byte order.

  reply	other threads:[~2020-05-06 13:53 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-06 12:54 [PATCH bpf-next 00/17] Run a BPF program on socket lookup Jakub Sitnicki
2020-05-06 12:54 ` [PATCH bpf-next 01/17] flow_dissector: Extract attach/detach/query helpers Jakub Sitnicki
2020-05-06 12:54 ` [PATCH bpf-next 02/17] bpf: Introduce SK_LOOKUP program type with a dedicated attach point Jakub Sitnicki
2020-05-06 13:16   ` Lorenz Bauer
2020-05-06 13:53     ` Jakub Sitnicki [this message]
2020-05-07 20:55       ` Martin KaFai Lau
2020-05-08  8:54         ` Jakub Sitnicki
2020-05-08  7:06   ` Martin KaFai Lau
2020-05-08 10:45     ` Jakub Sitnicki
2020-05-08 18:39       ` Martin KaFai Lau
2020-05-11  9:08         ` Jakub Sitnicki
2020-05-11 18:59           ` Martin KaFai Lau
2020-05-11 19:26             ` Jakub Sitnicki
2020-05-11 20:54               ` Martin KaFai Lau
2020-05-12 14:16                 ` Jakub Sitnicki
2020-05-06 12:54 ` [PATCH bpf-next 03/17] inet: Store layer 4 protocol in inet_hashinfo Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 04/17] inet: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 05/17] inet: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 06/17] inet6: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 07/17] inet6: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 08/17] udp: Store layer 4 protocol in udp_table Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 09/17] udp: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 10/17] udp: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 11/17] udp6: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 12/17] udp6: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 13/17] bpf: Sync linux/bpf.h to tools/ Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 14/17] libbpf: Add support for SK_LOOKUP program type Jakub Sitnicki
2020-05-08 17:41   ` Andrii Nakryiko
2020-05-08 17:52     ` Yonghong Song
2020-05-08 17:59       ` Andrii Nakryiko
2020-05-11  8:12     ` Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 15/17] selftests/bpf: Add verifier tests for bpf_sk_lookup context access Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 16/17] selftests/bpf: Rename test_sk_lookup_kern.c to test_ref_track_kern.c Jakub Sitnicki
2020-05-06 12:55 ` [PATCH bpf-next 17/17] selftests/bpf: Tests for BPF_SK_LOOKUP attach point Jakub Sitnicki

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