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 0D290C433FE for ; Thu, 6 Jan 2022 18:21:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242687AbiAFSVt (ORCPT ); Thu, 6 Jan 2022 13:21:49 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:43371 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242676AbiAFSVq (ORCPT ); Thu, 6 Jan 2022 13:21:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641493306; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZIrk+bfFu7JK7es/+sJfTXkxXQZhqqBoOQaxDDJ4K7g=; b=ZZn1byIGRP3OnljeufsGIMsSvA7XryXRHZqLMkqOH/AdV1o5MLLOHOzQgVvIWy+Peb4kDI oxnvpjwrkhCnpkxNBjDr6WlRxEKMo89tLNngWMrXLfVDmk5y+GD6CWPpUVoMiMvqHhU36x atnRSclZgYpYokxmv/CPPGhZ126hgr4= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-629-rIybZupRNkWhx_GoXEvQ0Q-1; Thu, 06 Jan 2022 13:21:45 -0500 X-MC-Unique: rIybZupRNkWhx_GoXEvQ0Q-1 Received: by mail-ed1-f70.google.com with SMTP id i5-20020a05640242c500b003f84839a8c3so2605636edc.6 for ; Thu, 06 Jan 2022 10:21:45 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version:content-transfer-encoding; bh=ZIrk+bfFu7JK7es/+sJfTXkxXQZhqqBoOQaxDDJ4K7g=; b=1OngfkywWso6ATKAs3cducDMn10lVhCjGSFHXAt2bcOm7SDesg/v2xWgmELxvoDcr/ hqjXl0sODK4Kgad2YSnPpc2Kh9f73r0k2fd4zyY013fD7f8zLec5mI0ziIH38+Oxt5FC ERHbWGXGUosKS4JCViZFUBs+bqTo8S1IevOcvP3O36yqADWGu0APzkahJjqCIMZSX8uc fQIgfR2HZzttAPrlZum3Oyg9w5o9jGw+ytxP20WCrp+Ay54RzFWer9KiILf/iUenp6Vq YLvTfsgp2H0QvSv60kdotAMizkw/MnwntElnmsZfyO2k6g7yjShtfBcXQRMyr82CQjTZ 4QQg== X-Gm-Message-State: AOAM532uf/1kDYTkkBaN8vuKXSyT3QFZUPDQ7vSFyII8NutqmkpldR/s pZ5510LIELrDjAJ1tgUzXVYRiVD/XNkVdaBB1SDd86ODtjrqj9hx1SFr2h4HHlknipBAHSCGbBT 66CkcNEHANlz6th5M X-Received: by 2002:a05:6402:128e:: with SMTP id w14mr57918102edv.161.1641493303022; Thu, 06 Jan 2022 10:21:43 -0800 (PST) X-Google-Smtp-Source: ABdhPJxWddGHE5gYcGtu0TY/FiDON2PbAvku8S1l5WCHmXgXN6WJ4tE/0bTGd0asV9ALstp2FQxUgQ== X-Received: by 2002:a05:6402:128e:: with SMTP id w14mr57918024edv.161.1641493301924; Thu, 06 Jan 2022 10:21:41 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id h10sm1031718edj.1.2022.01.06.10.21.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Jan 2022 10:21:41 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 40DA1181F2A; Thu, 6 Jan 2022 19:21:39 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Alexei Starovoitov Cc: Alexei Starovoitov , Daniel Borkmann , "David S. Miller" , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Shuah Khan , Network Development , bpf Subject: Re: [PATCH bpf-next v5 7/7] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run() In-Reply-To: References: <20220103150812.87914-1-toke@redhat.com> <20220103150812.87914-8-toke@redhat.com> <20220106042027.zy6j4a72nxaqmocw@ast-mbp.dhcp.thefacebook.com> <87y23t9blc.fsf@toke.dk> X-Clacks-Overhead: GNU Terry Pratchett Date: Thu, 06 Jan 2022 19:21:39 +0100 Message-ID: <87tuegafnw.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Alexei Starovoitov writes: > On Thu, Jan 6, 2022 at 6:34 AM Toke H=C3=B8iland-J=C3=B8rgensen wrote: >> >> Alexei Starovoitov writes: >> >> > On Mon, Jan 03, 2022 at 04:08:12PM +0100, Toke H=C3=B8iland-J=C3=B8rge= nsen wrote: >> >> + >> >> +#define NUM_PKTS 3 >> > >> > May be send a bit more than 3 packets? >> > Just to test skb_list logic for XDP_PASS. >> >> OK, can do. >> >> >> + >> >> + /* We setup a veth pair that we can not only XDP_REDIRECT packets >> >> + * between, but also route them. The test packet (defined above)= has >> >> + * address information so it will be routed back out the same in= terface >> >> + * after it has been received, which will allow it to be picked = up by >> >> + * the XDP program on the destination interface. >> >> + * >> >> + * The XDP program we run with bpf_prog_run() will cycle through= all >> >> + * four return codes (DROP/PASS/TX/REDIRECT), so we should end u= p with >> >> + * NUM_PKTS - 1 packets seen on the dst iface. We match the pack= ets on >> >> + * the UDP payload. >> >> + */ >> >> + SYS("ip link add veth_src type veth peer name veth_dst"); >> >> + SYS("ip link set dev veth_src address 00:11:22:33:44:55"); >> >> + SYS("ip link set dev veth_dst address 66:77:88:99:aa:bb"); >> >> + SYS("ip link set dev veth_src up"); >> >> + SYS("ip link set dev veth_dst up"); >> >> + SYS("ip addr add dev veth_src fc00::1/64"); >> >> + SYS("ip addr add dev veth_dst fc00::2/64"); >> >> + SYS("ip neigh add fc00::2 dev veth_src lladdr 66:77:88:99:aa:bb"= ); >> >> + SYS("sysctl -w net.ipv6.conf.all.forwarding=3D1"); >> > >> > These commands pollute current netns. The test has to create its own n= etns >> > like other tests do. >> >> Right, will fix. >> >> > The forwarding=3D1 is odd. Nothing in the comments or commit logs >> > talks about it. >> >> Hmm, yeah, should probably have added an explanation, sorry about that :) >> >> > I'm guessing it's due to patch 6 limitation of picking loopback >> > for XDP_PASS and XDP_TX, right? >> > There is ingress_ifindex field in struct xdp_md. >> > May be use that to setup dev and rxq in test_run in patch 6? >> > Then there will be no need to hack through forwarding=3D1 ? >> >> No, as you note there's already ingress_ifindex to set the device, and >> the test does use that: >> >> + memcpy(skel->rodata->expect_dst, &pkt_udp.eth.h_dest, ETH_ALEN); >> + skel->rodata->ifindex_out =3D ifindex_src; >> + ctx_in.ingress_ifindex =3D ifindex_src; > > My point is that this ingress_ifindex should be used instead of loopback. > Otherwise the test_run infra is lying to the xdp program. But it is already using that! There is just no explicit code in patch 6 to do that because that was already part of the XDP prog_run functionality. Specifically, the existing bpf_prog_test_run_xdp() will pass the context through xdp_convert_md_to_buff() which will resolve the ifindex and get a dev reference. So the xdp_buff object being passed to the new bpf_test_run_xdp_live() function already has the right device in ctx->rxq. I'll add a check for this to the selftest to make it explicit. >> I enable forwarding because the XDP program that counts the packets is >> running on the other end of the veth pair (on veth_dst), while the >> traffic gen is using veth_src as its ingress ifindex. So for XDP_TX and >> XDP_REDIRECT we send the frame back out the veth device, and it ends up >> being processed by the XDP program on veth_dst, and counted. > > Not for XDP_TX. If I'm reading patch 6 correctly it gets xmited > out of loopback. See above. >> But when >> the test program returns XDP_PASS, the packet will go up the frame; so >> to get it back to the counting program I enable forwarding and set the >> packet dst IP so that the stack routes it back out the same interface. >> >> I'll admit this is a bit hacky; I guess I can add a second TC ingress >> program that will count the packets being XDP_PASS'ed instead... > > No. Please figure out how to XDP_PASS and XDP_TX without enabling forward > and counting in different places. > imo the forwarding hides the issue in the design that should be addressed. > When rx ifindex is an actual ifindex given by user space instead of > loopback all problems go away. No the problem of XDP_PASS going in the opposite direction of XDP_TX and XDP_REDIRECT remains. This is just like on a physical interface: if you XDP_TX a packet it goes back out, if you XDP_PASS it, it goes up the stack. To intercept both after the fact, you need to look in two different places. Anyhow, just using a TC hook for XDP_PASS works fine and gets rid of the forwarding hack; I'll send a v6 with that just as soon as I verify that I didn't break anything when running the traffic generator on bare metal :) -Toke