netdev - Re: [PATCH net-next v5 02/15] net-timestamp: prepare for bpf prog use

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Message-ID: <5480eedb-ceb0-402e-883b-da4207dcc43d@linux.dev>
Date: Tue, 14 Jan 2025 15:39:37 -0800
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Jason Xing <kerneljasonxing@...il.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, dsahern@...nel.org, willemdebruijn.kernel@...il.com,
 willemb@...gle.com, ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
 eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev,
 john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me,
 haoluo@...gle.com, jolsa@...nel.org, horms@...nel.org, bpf@...r.kernel.org,
 netdev@...r.kernel.org
Subject: Re: [PATCH net-next v5 02/15] net-timestamp: prepare for bpf prog use

On 1/12/25 3:37 AM, Jason Xing wrote:
> Later, I would introduce three points to report some information
> to user space based on this.
> 
> Signed-off-by: Jason Xing <kerneljasonxing@...il.com>
> ---
>   include/net/sock.h |  7 +++++++
>   net/core/sock.c    | 14 ++++++++++++++
>   2 files changed, 21 insertions(+)
> 
> diff --git a/include/net/sock.h b/include/net/sock.h
> index f5447b4b78fd..dd874e8337c0 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -2930,6 +2930,13 @@ int sock_set_timestamping(struct sock *sk, int optname,
>   			  struct so_timestamping timestamping);
>   
>   void sock_enable_timestamps(struct sock *sk);
> +#if defined(CONFIG_CGROUP_BPF) && defined(CONFIG_BPF_SYSCALL)
> +void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op);
> +#else
> +static inline void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op)
> +{
> +}
> +#endif
>   void sock_no_linger(struct sock *sk);
>   void sock_set_keepalive(struct sock *sk);
>   void sock_set_priority(struct sock *sk, u32 priority);
> diff --git a/net/core/sock.c b/net/core/sock.c
> index eae2ae70a2e0..e06bcafb1b2d 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -948,6 +948,20 @@ int sock_set_timestamping(struct sock *sk, int optname,
>   	return 0;
>   }
>   
> +#if defined(CONFIG_CGROUP_BPF) && defined(CONFIG_BPF_SYSCALL)
> +void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op)
> +{
> +	struct bpf_sock_ops_kern sock_ops;
> +
> +	memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
> +	sock_ops.op = op;
> +	if (sk_is_tcp(sk) && sk_fullsock(sk))
> +		sock_ops.is_fullsock = 1;
> +	sock_ops.sk = sk;
> +	__cgroup_bpf_run_filter_sock_ops(sk, &sock_ops, CGROUP_SOCK_OPS);

hmm... I think I have already mentioned it in the earlier revision
(https://lore.kernel.org/bpf/f8e9ab4a-38b9-43a5-aaf4-15f95a3463d0@linux.dev/).

__cgroup_bpf_run_filter_sock_ops(sk, ...) requires sk to be fullsock.
Take a look at how BPF_CGROUP_RUN_PROG_SOCK_OPS does it.
sk_to_full_sk() is used to get back the listener. For other mini socks,
it needs to skip calling the cgroup bpf prog. I still don't understand
why BPF_CGROUP_RUN_PROG_SOCK_OPS cannot be used here because of udp.

> +}
> +#endif
> +
>   void sock_set_keepalive(struct sock *sk)
>   {
>   	lock_sock(sk);