Subject: RE: [PATCH RESEND bpf 2/4] bpf, sockmap: Fix missing BPF_F_INGRESS flag when using apply_bytes

From: John Fastabend <[email-masked]>
Date: Tue, 22 Nov 2022 19:02:51 -0800

Pengcheng Yang wrote:
> When redirecting, we use sk_msg_to_ingress() to get the BPF_F_INGRESS
> flag from the msg->flags. If apply_bytes is used and it is larger than
> the current data being processed, sk_psock_msg_verdict() will not be
> called when sendmsg() is called again. At this time, the msg->flags is 0,
> and we lost the BPF_F_INGRESS flag.
> 
> So we need to save the BPF_F_INGRESS flag in sk_psock and assign it to
> msg->flags before redirection.
> 
> Fixes: 8934ce2fd081 ("bpf: sockmap redirect ingress support")
> Signed-off-by: Pengcheng Yang <[email-masked]>
> ---
>  include/linux/skmsg.h | 1 +
>  net/core/skmsg.c      | 1 +
>  net/ipv4/tcp_bpf.c    | 1 +
>  net/tls/tls_sw.c      | 1 +
>  4 files changed, 4 insertions(+)
> 
> diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
> index 48f4b64..e1d463f 100644
> --- a/include/linux/skmsg.h
> +++ b/include/linux/skmsg.h
> @@ -82,6 +82,7 @@ struct sk_psock {
>  	u32				apply_bytes;
>  	u32				cork_bytes;
>  	u32				eval;
> +	u32				flags;
>  	struct sk_msg			*cork;
>  	struct sk_psock_progs		progs;
>  #if IS_ENABLED(CONFIG_BPF_STREAM_PARSER)
> diff --git a/net/core/skmsg.c b/net/core/skmsg.c
> index 188f855..ab2f8f3 100644
> --- a/net/core/skmsg.c
> +++ b/net/core/skmsg.c
> @@ -888,6 +888,7 @@ int sk_psock_msg_verdict(struct sock *sk, struct sk_psock *psock,
>  		if (psock->sk_redir)
>  			sock_put(psock->sk_redir);
>  		psock->sk_redir = msg->sk_redir;
> +		psock->flags = msg->flags;
>  		if (!psock->sk_redir) {
>  			ret = __SK_DROP;
>  			goto out;
> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
> index ef5de4f..1390d72 100644
> --- a/net/ipv4/tcp_bpf.c
> +++ b/net/ipv4/tcp_bpf.c
> @@ -323,6 +323,7 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
>  		break;
>  	case __SK_REDIRECT:
>  		sk_redir = psock->sk_redir;
> +		msg->flags = psock->flags;
>  		sk_msg_apply_bytes(psock, tosend);
>  		if (!psock->apply_bytes) {
>  			/* Clean up before releasing the sock lock. */
                 ^^^^^^^^^^^^^^^
In this block reposted here with the rest of the block

		if (!psock->apply_bytes) {
			/* Clean up before releasing the sock lock. */
			eval = psock->eval;
			psock->eval = __SK_NONE;
			psock->sk_redir = NULL;
		}

Now that we have a psock->flags we should clera that as
well right?