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From: Jamal Hadi Salim <jhs@mojatatu.com>
To: Joe Stringer <joe@wand.net.nz>
Cc: bpf <bpf@vger.kernel.org>, netdev <netdev@vger.kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Alexei Starovoitov <ast@kernel.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Lorenz Bauer <lmb@cloudflare.com>,
	Martin KaFai Lau <kafai@fb.com>, Roman Mashak <mrv@mojatatu.com>
Subject: Re: [PATCHv3 bpf-next 0/5] Add bpf_sk_assign eBPF helper
Date: Fri, 27 Mar 2020 14:34:09 -0400	[thread overview]
Message-ID: <52f33dc9-734c-d509-8da3-3e2cbdbaec45@mojatatu.com> (raw)
In-Reply-To: <CAOftzPjWtL5a5j3GAJW5SOhWS1Jx43XWSwb7ksTaXC5-sAaw2w@mail.gmail.com>

On 2020-03-27 1:43 p.m., Joe Stringer wrote:
> On Fri, Mar 27, 2020 at 7:14 AM Jamal Hadi Salim <jhs@mojatatu.com> wrote:
>>

[..]
>>
>> Trying to understand so if we can port our tc action (and upstream),
>> we would need to replicate:
>>
>>    bpf_sk_assign() - invoked everytime we succeed finding the sk
>>    bpf_sk_release() - invoked everytime we are done processing the sk
> 
> The skb->destructor = sock_pfree() is the balanced other half of
> bpf_sk_assign(), so you shouldn't need to explicitly call
> bpf_sk_release() to handle the refcounting of the assigned socket.
>

per other thread, I think once you factor out what those two functions
call into the kernel proper we will just call those same
things..

> The `bpf_sk_release()` pairs with BPF socket lookup, so if you already
> have other socket lookup code handling the core tproxy logic (looking
> up established, then looking up listen sockets with different tuple)
> then you're presumably already handling that to avoid leaking
> references.
> 

Yes, we have all that code already.

> I think that looking at the test_sk_assign.c BPF program in patch 4/5
> should give you a good sense for what you'd need in the TC action
> logic.

Seems like we are on track. Thanks again for working on this.

cheers,
jamal



  reply	other threads:[~2020-03-27 18:34 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-27  4:25 [PATCHv3 bpf-next 0/5] Add bpf_sk_assign eBPF helper Joe Stringer
2020-03-27  4:25 ` [PATCHv3 bpf-next 1/5] bpf: Add socket assign support Joe Stringer
2020-03-27 18:44   ` Martin KaFai Lau
2020-03-27  4:25 ` [PATCHv3 bpf-next 2/5] net: Track socket refcounts in skb_steal_sock() Joe Stringer
2020-03-27 18:45   ` Martin KaFai Lau
2020-03-27  4:25 ` [PATCHv3 bpf-next 3/5] bpf: Don't refcount LISTEN sockets in sk_assign() Joe Stringer
2020-03-27 14:26   ` Jamal Hadi Salim
2020-03-27 17:38     ` Joe Stringer
2020-03-27 18:29       ` Jamal Hadi Salim
2020-03-27  4:25 ` [PATCHv3 bpf-next 4/5] selftests: bpf: add test for sk_assign Joe Stringer
2020-03-27  4:25 ` [PATCHv3 bpf-next 5/5] selftests: bpf: Extend sk_assign tests for UDP Joe Stringer
     [not found]   ` <CACAyw9-GOw5tkR8n6p7Kct9-wq4B-9ka-X8R2V8uZv8VWUY5UQ@mail.gmail.com>
2020-03-27 19:37     ` Joe Stringer
2020-03-27  5:02 ` [PATCHv3 bpf-next 0/5] Add bpf_sk_assign eBPF helper Alexei Starovoitov
2020-03-27  5:42   ` Eric Dumazet
2020-03-27 14:13 ` Jamal Hadi Salim
2020-03-27 17:43   ` Joe Stringer
2020-03-27 18:34     ` Jamal Hadi Salim [this message]
2020-03-27 18:46 ` Martin KaFai Lau
2020-03-27 21:05   ` Joe Stringer
2020-03-28 17:25     ` Daniel Borkmann
2020-03-28 17:42       ` Joe Stringer

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