The convention seems to be to call tcp_checksum_complete after tcp_filter has a
chance to deal with the packet. I wanted to preserve that.
If that is not a concern, then I agree that this is a far better way to go.
Frank
On 6/12/18, 2:50 PM, "Eric Dumazet" <eric.duma...@gmail.com> wrote:
On 06/12/2018 02:41 PM, Frank van der Linden wrote:
> commit 079096f103fa ("tcp/dccp: install syn_recv requests into ehash
> table") introduced an optimization for the handling of child sockets
> created for a new TCP connection.
>
> But this optimization passes any data associated with the last ACK of the
> connection handshake up the stack without verifying its checksum, because
it
> calls tcp_child_process(), which in turn calls tcp_rcv_state_process()
> directly. These lower-level processing functions do not do any checksum
> verification.
>
> Insert a tcp_checksum_complete call in the TCP_NEW_SYN_RECEIVE path to
> fix this.
>
> Signed-off-by: Frank van der Linden <fllin...@amazon.com>
This is way too complicated.
You should call tcp_checksum_complete() earlier and avoid all this mess.
IPV4 part shown here :
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index
fed3f1c6616708997f621535efe9412e4afa0a50..7b5f32aa3835b0124b0a9bd342c371df7b46f471
100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1730,6 +1730,10 @@ int tcp_v4_rcv(struct sk_buff *skb)
reqsk_put(req);
goto discard_it;
}
+ if (unlikely(tcp_checksum_complete(skb))) {
+ reqsk_put(req);
+ goto csum_error;
+ }
if (unlikely(sk->sk_state != TCP_LISTEN)) {
inet_csk_reqsk_queue_drop_and_put(sk, req);
goto lookup;
