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From: David Ahern <dsahern@kernel.org>
To: Stanislav Fomichev <sdf@google.com>, Gilad Sever <gilad9366@gmail.com>
Cc: martin.lau@linux.dev, daniel@iogearbox.net,
	john.fastabend@gmail.com, ast@kernel.org, andrii@kernel.org,
	song@kernel.org, yhs@fb.com, kpsingh@kernel.org,
	haoluo@google.com, jolsa@kernel.org, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	mykolal@fb.com, shuah@kernel.org, hawk@kernel.org,
	joe@wand.net.nz, eyal.birger@gmail.com,
	shmulik.ladkani@gmail.com, bpf@vger.kernel.org,
	netdev@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH bpf,v2 0/4] Socket lookup BPF API from tc/xdp ingress does not respect VRF bindings.
Date: Mon, 24 Apr 2023 19:39:01 -0600	[thread overview]
Message-ID: <09814247-07ca-5945-8b6e-9dc1632c1e45@kernel.org> (raw)
In-Reply-To: <CAKH8qBuntApFvGYEs_fU_OAsQeP_Uf2sdrEMAtB4rS6c6fhF9A@mail.gmail.com>

On 4/24/23 11:06 AM, Stanislav Fomichev wrote:
>> - xdp callers would check the device's l3 enslaved state using the new
>> `dev_sdif()`
>> - sock_addr callers would use inet{,6}_sdif() as they did before
>> - cg/tc share the same code path, so when netif_is_l3_master() is true
>>    use inet{,6}_sdif() and when it is false use dev_sdif(). this relies
>> on the following
>>    assumptions:
>>    - tc programs don't run on l3 master devices

this can happen, but I am not sure how prevalent a use case.

>>    - cgroup callers never see l3 enslaved devices

egress definitely, not sure on ingress. The code resets the skb->dev
back to the original device in a lot of places in the ip/ipv6 code now.
And ipv6 brings up LLAs and those did not get the device switch so it
could be fairly common.

>>    - inet{,6}_sdif() isn't relevant for non l3 master devices

sdif should be 0 and not matched if a netdev is not a l3mdev port.

BTW, in skimming the patches, I noticed patch 3 has bpf_l2_sdif which
seems an odd name to me. It returns a layer 3 device index, not a layer
2 which would be a bridge port. I would stick to the l3 naming for
consistency.

> 
> Yeah, that's what I was assuming we should be able to do..
> But we probably need somebody who understands this part better than me
> to say whether the above are safe..
> 
> If nobody comments, ignore me and do a v2 with your original approach.


      reply	other threads:[~2023-04-25  1:39 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-20 14:50 [PATCH bpf,v2 0/4] Socket lookup BPF API from tc/xdp ingress does not respect VRF bindings Gilad Sever
2023-04-20 14:50 ` [PATCH bpf,v2 1/4] bpf: factor out socket lookup functions for the TC hookpoint Gilad Sever
2023-04-20 14:50 ` [PATCH bpf,v2 2/4] bpf: Call __bpf_sk_lookup()/__bpf_skc_lookup() directly via " Gilad Sever
2023-04-20 14:50 ` [PATCH bpf,v2 3/4] bpf: fix bpf socket lookup from tc/xdp to respect socket VRF bindings Gilad Sever
2023-04-20 14:50 ` [PATCH bpf,v2 4/4] selftests/bpf: Add tc_socket_lookup tests Gilad Sever
2023-04-20 16:44   ` Stanislav Fomichev
2023-04-21 17:01     ` Daniel Borkmann
2023-04-23  9:31     ` Gilad Sever
2023-04-24 17:06       ` Stanislav Fomichev
2023-04-20 16:42 ` [PATCH bpf,v2 0/4] Socket lookup BPF API from tc/xdp ingress does not respect VRF bindings Stanislav Fomichev
2023-04-23 11:41   ` Gilad Sever
2023-04-24 17:06     ` Stanislav Fomichev
2023-04-25  1:39       ` David Ahern [this message]

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