From: Yonghong Song <yhs@meta.com>
To: Kui-Feng Lee <thinker.li@gmail.com>,
bpf@vger.kernel.org, ast@kernel.org, martin.lau@linux.dev,
song@kernel.org, kernel-team@meta.com, andrii@kernel.org,
daniel@iogearbox.net, yhs@fb.com, kpsingh@kernel.org,
shuah@kernel.org, john.fastabend@gmail.com, sdf@google.com,
mykolal@fb.com, linux-kselftest@vger.kernel.org,
jolsa@kernel.org, haoluo@google.com
Cc: Kui-Feng Lee <kuifeng@meta.com>
Subject: Re: [PATCH bpf-next v3 1/2] net: bpf: Always call BPF cgroup filters for egress.
Date: Wed, 21 Jun 2023 20:37:50 -0700 [thread overview]
Message-ID: <4d46ba3a-61e9-2482-a359-7a8805f1dbc8@meta.com> (raw)
In-Reply-To: <20230620171409.166001-2-kuifeng@meta.com>
On 6/20/23 10:14 AM, Kui-Feng Lee wrote:
> Always call BPF filters if CGROUP BPF is enabled for EGRESS without
> checking skb->sk against sk.
>
> The filters were called only if skb is owned by the sock that the
> skb is sent out through. In another words, skb->sk should point to
> the sock that it is sending through its egress. However, the filters would
> miss SYNACK skbs that they are owned by a request_sock but sent through
> the listening sock, that is the socket listening incoming connections.
> This is an unnecessary restrict.
The original patch which introduced 'sk == skb->sk' is
3007098494be cgroup: add support for eBPF programs
There are no mentioning in commit message why 'sk == skb->sk'
is needed. So it is possible that this is just restricted
for use cases at that moment. Now there are use cases
where 'sk != skb->sk' so removing this check can enable
the new use case. Maybe you can add this into your commit
message so people can understand the history of 'sk == skb->sk'.
>
> Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
> ---
> include/linux/bpf-cgroup.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
> index 57e9e109257e..e656da531f9f 100644
> --- a/include/linux/bpf-cgroup.h
> +++ b/include/linux/bpf-cgroup.h
> @@ -199,7 +199,7 @@ static inline bool cgroup_bpf_sock_enabled(struct sock *sk,
> #define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb) \
> ({ \
> int __ret = 0; \
> - if (cgroup_bpf_enabled(CGROUP_INET_EGRESS) && sk && sk == skb->sk) { \
> + if (cgroup_bpf_enabled(CGROUP_INET_EGRESS) && sk) { \
> typeof(sk) __sk = sk_to_full_sk(sk); \
> if (sk_fullsock(__sk) && \
> cgroup_bpf_sock_enabled(__sk, CGROUP_INET_EGRESS)) \
next prev parent reply other threads:[~2023-06-22 3:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-20 17:14 [PATCH bpf-next v3 0/2] Fix missing synack in BPF cgroup_skb filters Kui-Feng Lee
2023-06-20 17:14 ` [PATCH bpf-next v3 1/2] net: bpf: Always call BPF cgroup filters for egress Kui-Feng Lee
2023-06-22 3:37 ` Yonghong Song [this message]
2023-06-22 15:34 ` Kui-Feng Lee
2023-06-22 17:15 ` Kui-Feng Lee
2023-06-22 18:28 ` Yonghong Song
2023-06-22 20:06 ` Daniel Borkmann
2023-06-22 23:55 ` Kui-Feng Lee
2023-06-23 8:50 ` Daniel Borkmann
2023-06-23 16:30 ` Kui-Feng Lee
2023-06-20 17:14 ` [PATCH bpf-next v3 2/2] selftests/bpf: Verify that the cgroup_skb filters receive expected packets Kui-Feng Lee
2023-06-22 4:15 ` Yonghong Song
2023-06-22 15:33 ` Kui-Feng Lee
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