From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH v2] tcp: verify the checksum of the first data segment in a new connection Date: Tue, 12 Jun 2018 14:50:44 -0700 Message-ID: <9541859a-1346-e13a-b97c-a2a63f3b19f4@gmail.com> References: <5b203e1b.vy4yU6CwMEwLmNtj%fllinden@amazon.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit To: Frank van der Linden , edumazet@google.com, netdev@vger.kernel.org Return-path: Received: from mail-pl0-f68.google.com ([209.85.160.68]:33502 "EHLO mail-pl0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754400AbeFLVuq (ORCPT ); Tue, 12 Jun 2018 17:50:46 -0400 Received: by mail-pl0-f68.google.com with SMTP id n10-v6so252289plp.0 for ; Tue, 12 Jun 2018 14:50:45 -0700 (PDT) In-Reply-To: <5b203e1b.vy4yU6CwMEwLmNtj%fllinden@amazon.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: 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 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;