On Thu, Jan 09, 2025 at 05:43 PM +08, Jiayuan Chen wrote: > '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, > the update logic for 'sk->copied_seq' was moved to > tcp_bpf_recvmsg_parser() to ensure the accuracy of the 'fionread' feature. > > It works for a single stream_verdict scenario, as it also modified > 'sk_data_ready->sk_psock_verdict_data_ready->tcp_read_skb' > to remove updating 'sk->copied_seq'. > > However, for programs where both stream_parser and stream_verdict are > active(strparser purpose), tcp_read_sock() was used instead of > tcp_read_skb() (sk_data_ready->strp_data_ready->tcp_read_sock) > tcp_read_sock() now still update 'sk->copied_seq', leading to duplicated > updates. > > In summary, for strparser + SK_PASS, copied_seq is redundantly calculated > in both tcp_read_sock() and tcp_bpf_recvmsg_parser(). > > The issue causes incorrect copied_seq calculations, which prevent > correct data reads from the recv() interface in user-land. > > We do not want to add new proto_ops to implement a new version of > tcp_read_sock, as this would introduce code complexity [1]. > > [1]: https://lore.kernel.org/bpf/20241218053408.437295-1-mrpre@xxxxxxx > Fixes: e5c6de5fa025 ("bpf, sockmap: Incorrectly handling copied_seq") > Co-developed-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> > Signed-off-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> > Signed-off-by: Jiayuan Chen <mrpre@xxxxxxx> > --- No need to put me down as an author. If you want you can me with a Suggested-by. Also, please remove my Signed-off-by. I will review these patches, but I haven't authored them.
