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 DEF6CECAAD1 for ; Thu, 1 Sep 2022 06:10:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232580AbiIAGKs (ORCPT ); Thu, 1 Sep 2022 02:10:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231752AbiIAGKr (ORCPT ); Thu, 1 Sep 2022 02:10:47 -0400 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B86C9BB01A for ; Wed, 31 Aug 2022 23:10:46 -0700 (PDT) Received: by mail-wr1-x42a.google.com with SMTP id b5so20898542wrr.5 for ; Wed, 31 Aug 2022 23:10:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=metanetworks.com; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date; bh=BSZ8RYQwsEq+ZHDeMsWovu5X93zcXLSLqCbeRmnPF0g=; b=Q9tdOAtZSvK1cKFUHCrrmy+dNrwbqG4v5Ux2iG7WztwgCgXctUHZVd6nt57AC+o+f/ i7BS4oMD+HiWKMsfp2qQSkb42Dw9bEBw/RyPL2+wXdQC3XFUPFR5g3WOk2AbVQmkoJOh 7G87x0O84Dy6O6OWkQGBzUU12o1+oxLUgygcs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date; bh=BSZ8RYQwsEq+ZHDeMsWovu5X93zcXLSLqCbeRmnPF0g=; b=rD3QUwYtq3JS+468lSnesLFxQCeFxAK+cO+5v23eUBoSfWeIUWL3OXO+13e3cRWlfT UHTEBw4b+cAf6AR1dAVf7La6dv/UXEbhhhO7IpaJUjThQtkewjnd6anXh+HegZP1PJMU 7gq1HBGQMiXlbahsqV/PD7CEIQGxFSomcKPvT+XXY1UE0E5F5qgu8ujCIQkMpzHvyR97 G9o9ZEIwzUARS88bCjlIBuofH0nmOhf8PSHpx64t0RzsvMZZcRKCLw1ow8qzK1c686vt V+YPF3xptqA7w1n8gP79BWfBK7edZkgi3n2kQwMeZtS0CjjTW9VCtE3Ew/nHo7WgaK4U gWzg== X-Gm-Message-State: ACgBeo1WZEjvPEhumUPmJA11MAOc5nPACwolLj3sjRi+smmiYSs8kx4D FGllX6d5EgEu6Qpe8PhXFFzXOg== X-Google-Smtp-Source: AA6agR5n1yptRTC/Isqzm+FAkqPBEptlcnlvS0EMZbFPLukJVercrl+f04L1tu5fp6pktl+ps/L8Ng== X-Received: by 2002:a05:6000:4005:b0:225:8b27:e6d5 with SMTP id cy5-20020a056000400500b002258b27e6d5mr13516657wrb.603.1662012645267; Wed, 31 Aug 2022 23:10:45 -0700 (PDT) Received: from blondie ([5.102.239.127]) by smtp.gmail.com with ESMTPSA id v16-20020a5d6790000000b0021f0c0c62d1sm13715385wru.13.2022.08.31.23.10.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Aug 2022 23:10:44 -0700 (PDT) Date: Thu, 1 Sep 2022 09:10:40 +0300 From: Shmulik Ladkani To: Daniel Borkmann Cc: bpf@vger.kernel.org, Alexei Starovoitov , Andrii Nakryiko , Shmulik Ladkani Subject: Re: [PATCH bpf-next 1/2] bpf: Support getting tunnel flags Message-ID: <20220901091040.2fcd73af@blondie> In-Reply-To: <3b4e74bb-5ede-e773-69e6-6c272ffa2459@iogearbox.net> References: <20220831144010.174110-1-shmulik.ladkani@gmail.com> <3b4e74bb-5ede-e773-69e6-6c272ffa2459@iogearbox.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, 31 Aug 2022 22:46:15 +0200 Daniel Borkmann wrote: > The bpf_skb_set_tunnel_key() helper has a number of flags we pass in, e.g. > BPF_F_ZERO_CSUM_TX, BPF_F_DONT_FRAGMENT, BPF_F_SEQ_NUMBER, and then based on > those flags we set: > > [...] > info->key.tun_flags = TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_NOCACHE; > if (flags & BPF_F_DONT_FRAGMENT) > info->key.tun_flags |= TUNNEL_DONT_FRAGMENT; > if (flags & BPF_F_ZERO_CSUM_TX) > info->key.tun_flags &= ~TUNNEL_CSUM; > if (flags & BPF_F_SEQ_NUMBER) > info->key.tun_flags |= TUNNEL_SEQ; > [...] > > Should we similarly only expose those which are interesting/relevant to BPF > program authors as a __u16 tunnel_flags and not the whole set? Which ones > do you have a need for? TUNNEL_SEQ, TUNNEL_CSUM, TUNNEL_KEY, and then the > TUNNEL_OPTIONS_PRESENT? Indeed, I noticed this and considered various approaches: 1. Convert the "interesting" internal TUNNEL_xxx flags back to BPF_F_yyy and place into the new 'tunnel_flags' field. This has 2 drawbacks: - The BPF_F_yyy flags are from *set_tunnel_key* enumeration space, e.g. BPF_F_ZERO_CSUM_TX. I find it awkward that it is "returned" into tunnel_flags from a *get_tunnel_key* call. - Not all "interesting" TUNNEL_xxx flags can be mapped to existing BPF_F_yyy flags, and it doesn't make sense to create new BPF_F_yyy flags just for purposes of the returned tunnel_flags. 2. Place key.tun_flags into 'tunnel_flags' but mask them, keeping only "interesting" flags. That's ok, but the drawback is that what's "intersting" for my usecase might be limiting for other usecases. Therefore I decided to expose what's in key.tun_flags *as is*, which seems most flexible. The bpf user can just choose to ingore bits he's not interested in. The TUNNEL_xxx are uapi, so no harm exposing them back in the get_tunnel_key call. WDYT? Best, Shmulik