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 X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A3DDC10F27 for ; Wed, 11 Mar 2020 13:44:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6485F20873 for ; Wed, 11 Mar 2020 13:44:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="KRP2PUDe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729541AbgCKNog (ORCPT ); Wed, 11 Mar 2020 09:44:36 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:42265 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729528AbgCKNof (ORCPT ); Wed, 11 Mar 2020 09:44:35 -0400 Received: by mail-wr1-f66.google.com with SMTP id v11so2668263wrm.9 for ; Wed, 11 Mar 2020 06:44:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=references:user-agent:from:to:cc:subject:in-reply-to:date :message-id:mime-version; bh=ePCb0df9gTgL2UMkffHBZ8+8Oebpm89G0Wlrp433HuU=; b=KRP2PUDeNB/O1UBpVlIMzs05+FLZ8Vdfnk97LeVezQukugJ+Tb80QNk/UMdRkwSe0Y 5DOBug6jB9Fgib2wxxmU117vUnWT+b+OdSmdTXavoSpLL4lSbreGgBE/dFzu5BKjj51t TbifQ3QbaLgTBh052z7ymdH79Lc1iiWhtZ3i0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject :in-reply-to:date:message-id:mime-version; bh=ePCb0df9gTgL2UMkffHBZ8+8Oebpm89G0Wlrp433HuU=; b=MAmM/do2mny6lkVmoxvmvYHMEgfkl+5hq31POXeC/D695M+PCd7KURr7sNrihnjX9G uYuaeLH6A4GK39l7Msa76T5eVDIGzv5wYSktoBrmax4vnRRAjDkdw1NiDvadXYwIG08V DwOHHCXhcpV0vuwijwRT9KaqvQ9kNShQVoTe37BCyWSsTqUrsKUBPN1wKgR/x5/Dt87h szCEf/LRGg8yrQ4PLYZyQB8cxjbDCRqj57R+XCOgWhAgkSI0TJlGuVGslDIlE22YpkLo i9ZHlkgWGyB9mMBVcRhKT8ufLO7zwF9EdDPBKwMO0zxzzz8q+WBGk2ed0TwzR1Huet/0 VIrg== X-Gm-Message-State: ANhLgQ3T+Shx/MsMpTVOg0rn8NtLqetLY+oqreKBPLu0YI876Ds2LVQW jZy7Nno/mVDf0MTZq9AdHpvBNA== X-Google-Smtp-Source: ADFU+vsj1xa7sgaLweZwfOTQi81O2oOmGxS6Ap2wvC/10sv0ZXwVnw+i5qycYS2tqv3VMGLhdPH+Hg== X-Received: by 2002:adf:e64f:: with SMTP id b15mr1623447wrn.424.1583934273745; Wed, 11 Mar 2020 06:44:33 -0700 (PDT) Received: from cloudflare.com ([176.221.114.230]) by smtp.gmail.com with ESMTPSA id w15sm6670639wrm.9.2020.03.11.06.44.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2020 06:44:33 -0700 (PDT) References: <20200310174711.7490-1-lmb@cloudflare.com> User-agent: mu4e 1.1.0; emacs 26.3 From: Jakub Sitnicki To: Daniel Borkmann , John Fastabend Cc: Alexei Starovoitov , Lorenz Bauer , kernel-team@cloudflare.com, netdev@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH 0/5] Return fds from privileged sockhash/sockmap lookup In-reply-to: <20200310174711.7490-1-lmb@cloudflare.com> Date: Wed, 11 Mar 2020 14:44:32 +0100 Message-ID: <87y2s7xayn.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, Mar 10, 2020 at 06:47 PM CET, Lorenz Bauer wrote: > We want to use sockhash and sockmap to build the control plane for > our upcoming BPF socket dispatch work. We realised that it's > difficult to resize or otherwise rebuild these maps if needed, > because there is no way to get at their contents. This patch set > allows a privileged user to retrieve fds from these map types, > which removes this obstacle. Since it takes just a few lines of code to get an FD for a sock: fd = get_unused_fd_flags(O_CLOEXEC); if (unlikely(fd < 0)) return fd; fd_install(fd, get_file(sk->sk_socket->file)); ... I can't help but wonder where's the catch? IOW, why wasn't this needed so far? How does Cilium avoid resizing & rebuilding sockmaps? Just asking out of curiosity. [...]