From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A839C433FE for ; Sat, 1 Oct 2022 20:33:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229582AbiJAUd3 (ORCPT ); Sat, 1 Oct 2022 16:33:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48016 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229436AbiJAUd1 (ORCPT ); Sat, 1 Oct 2022 16:33:27 -0400 Received: from mail-qk1-x734.google.com (mail-qk1-x734.google.com [IPv6:2607:f8b0:4864:20::734]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D58A45061 for ; Sat, 1 Oct 2022 13:33:24 -0700 (PDT) Received: by mail-qk1-x734.google.com with SMTP id g2so4754056qkk.1 for ; Sat, 01 Oct 2022 13:33:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=Fk8jhK0skKxmeJUb5JNgCy7u78GSdLOZ+JXwdVte/fA=; b=GWZoJNSNgsKmjZStlYXT4F+bvFSpCCh4690pd8pD3BK95FnuMJjEh+3xCgKuPjFNCP l46WB9engVqlCgBqxg+Z7iPTXRM9qaTjjY/2FwnMt5QhDVnC1bOlkkWT+40uCKyB1z+h LBScXMZjEqIAidK5pCnKprHWFf7KGlQl+++DnsVeO95YmHtI6HEAWgQNbnt2H6l133Na ZEQ8n6ss9UNPfM/lVVXBiOMAFYPN/EkGjn2BG9HAsAdF8hmtk4LgE0R+Nr8qvNWvB6te 2ABkvdq2vK8By0wk61iy4+ER0jZO6aQ/EwcjNnzrfA+b162Ll0bz8SVqBLWrwM3hjHK0 3l/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=Fk8jhK0skKxmeJUb5JNgCy7u78GSdLOZ+JXwdVte/fA=; b=pZJ49QxQd54aRZAMZyAA2VsV6SjkMWMQNNz9GksqqGNQIrOtR/lcXBZDBaqqXb96yG JOMNwHRiMA7npFY20naja2c2yq6hNCAkdHFe6l4KGhKSCRf70d9mJC0y7AYch2dvpCft rVex29HzAzX01BaDx9m6HYWoooNOXd4d3eSfAWF4rzV4iDowcpsOZyl2qKcV1wJtxukZ viLHTZ1iSV8VKgJiWANwtHEk7PdgU06kLvLdW+4KT9ODKWYdeNbuQpedepQUSdby3l1T izqlBXBBDuNi/x6Z01PsOoMSJ4HX6tx0HkRa8qOYv25wsldmBTNrIf51WnCqrrQTA+IX pd0A== X-Gm-Message-State: ACrzQf00fEbqW/wUMr/qkHafLAbP1JUZKh/DUx5iBES94cP6o95whwbV dlRnmKygsBmW3GduqSB/2RW2Im4xuyU= X-Google-Smtp-Source: AMsMyM4akFSyTAV1gFNNdJBUkbYcQdp1cScIVn4oj0tm+rS24YbK353ucR478sx8RJZO3X0+6hwjJA== X-Received: by 2002:a37:c49:0:b0:6cc:43ac:a29a with SMTP id 70-20020a370c49000000b006cc43aca29amr9885684qkm.763.1664656403623; Sat, 01 Oct 2022 13:33:23 -0700 (PDT) Received: from localhost ([2600:1700:65a0:ab60:a570:880e:2c92:fa00]) by smtp.gmail.com with ESMTPSA id bl11-20020a05620a1a8b00b006ce30a5f892sm6060391qkb.102.2022.10.01.13.33.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 01 Oct 2022 13:33:22 -0700 (PDT) Date: Sat, 1 Oct 2022 13:33:19 -0700 From: Cong Wang To: Paul Blakey Cc: Daniel Borkmann , Vlad Buslov , Oz Shlomo , Roi Dayan , netdev@vger.kernel.org, Saeed Mahameed , Eric Dumazet , "David S. Miller" , Jakub Kicinski , Paolo Abeni Subject: Re: [PATCH net v2 1/2] net: Fix return value of qdisc ingress handling on success Message-ID: References: <1664093662-32069-1-git-send-email-paulb@nvidia.com> <1664093662-32069-2-git-send-email-paulb@nvidia.com> <5a9d0e6a-2916-e791-a123-c8a957a3e3e5@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Oct 01, 2022 at 01:19:50PM -0700, Cong Wang wrote: > On Wed, Sep 28, 2022 at 10:55:49AM +0300, Paul Blakey wrote: > > > > > > On 25/09/2022 21:00, Cong Wang wrote: > > > On Sun, Sep 25, 2022 at 11:14:21AM +0300, Paul Blakey wrote: > > > > Currently qdisc ingress handling (sch_handle_ingress()) doesn't > > > > set a return value and it is left to the old return value of > > > > the caller (__netif_receive_skb_core()) which is RX drop, so if > > > > the packet is consumed, caller will stop and return this value > > > > as if the packet was dropped. > > > > > > > > This causes a problem in the kernel tcp stack when having a > > > > egress tc rule forwarding to a ingress tc rule. > > > > The tcp stack sending packets on the device having the egress rule > > > > will see the packets as not successfully transmitted (although they > > > > actually were), will not advance it's internal state of sent data, > > > > and packets returning on such tcp stream will be dropped by the tcp > > > > stack with reason ack-of-unsent-data. See reproduction in [0] below. > > > > > > > > > > Hm, but how is this return value propagated to egress? I checked > > > tcf_mirred_act() code, but don't see how it is even used there. > > > > > > 318 err = tcf_mirred_forward(want_ingress, skb2); > > > 319 if (err) { > > > 320 out: > > > 321 tcf_action_inc_overlimit_qstats(&m->common); > > > 322 if (tcf_mirred_is_act_redirect(m_eaction)) > > > 323 retval = TC_ACT_SHOT; > > > 324 } > > > 325 __this_cpu_dec(mirred_rec_level); > > > 326 > > > 327 return retval; > > > > > > > > > What am I missing? > > > > for the ingress acting act_mirred it will return TC_ACT_CONSUMED above > > the code you mentioned (since redirect=1, use_reinsert=1. Although > > TC_ACT_STOLEN which is the retval set for this action, will also act the > > same) > > > > > > It is propagated as such (TX stack starting from tcp): > > > > Sorry for my misunderstanding. > > I meant to say those TC_ACT_* return value, not NET_RX_*, but I worried > too much here, as mirred lets user specify the return value. > > BTW, it seems you at least miss the drop case, which is NET_RX_DROP for > TC_ACT_SHOT at least? Possibly other code paths in sch_handle_ingress() > too. > I mean: diff --git a/net/core/dev.c b/net/core/dev.c index fa53830d0683..d1db8210d671 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5109,6 +5109,7 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret, struct mini_Qdisc *miniq = rcu_dereference_bh(skb->dev->miniq_ingress); struct tcf_result cl_res; + *ret = NET_RX_SUCCESS; /* If there's at least one ingress present somewhere (so * we get here via enabled static key), remaining devices * that are not configured with an ingress qdisc will bail @@ -5136,6 +5137,7 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret, case TC_ACT_SHOT: mini_qdisc_qstats_cpu_drop(miniq); kfree_skb_reason(skb, SKB_DROP_REASON_TC_INGRESS); + *ret = NET_RX_DROP; return NULL; case TC_ACT_STOLEN: case TC_ACT_QUEUED: @@ -5160,6 +5162,7 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret, break; } #endif /* CONFIG_NET_CLS_ACT */ + *ret = NET_RX_SUCCESS; return skb; }