Re: [PATCH bpf v7 2/5] bpf: fix wrong copied_seq calculation

On Mon, Jan 20, 2025 at 11:35 AM +08, Jiayuan Chen wrote:

On Sat, Jan 18, 2025 at 11:29:04PM +0800, Jiayuan Chen wrote:

quoted

On Sat, Jan 18, 2025 at 03:50:22PM +0100, Jakub Sitnicki wrote:

quoted

On Thu, Jan 16, 2025 at 10:05 PM +08, Jiayuan Chen wrote:

quoted

'sk->copied_seq' was updated in the tcp_eat_skb() function when the
action of a BPF program was SK_REDIRECT. For other actions, like SK_PASS,
+}
+#endif /* CONFIG_BPF_STREAM_PARSER */
+
 int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
 {
 	int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;

@@ -681,6 +722,12 @@ int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
 
 	/* Pairs with lockless read in sk_clone_lock() */
 	sock_replace_proto(sk, &tcp_bpf_prots[family][config]);
+#if IS_ENABLED(CONFIG_BPF_STREAM_PARSER)
+	if (psock->progs.stream_parser && psock->progs.stream_verdict) {
+		psock->copied_seq = tcp_sk(sk)->copied_seq;
+		psock->read_sock = tcp_bpf_strp_read_sock;

Just directly set psock->strp.cb.read_sock to tcp_bpf_strp_read_sock.
Then we don't need this intermediate psock->read_sock callback, which
doesn't do anything useful.

Ok, I will do this.
(BTW, I intended to avoid bringing "struct strparser" into tcp_bpf.c so I
added a wrapper function instead in skmsg.c without calling it directly) 

I find that tcp_bpf_update_proto is called before sk_psock_init_strp. Any
assignment of psock->cb.strp will be overwritten in sk_psock_init_strp.

Or just don't set ->read_sock in strp_init.
It's being reset only because you made it so in patch 1 :-)