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=-1.0 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 58078C54E8D for ; Mon, 11 May 2020 09:08:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 383FC207DD for ; Mon, 11 May 2020 09:08:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="eDGPh8Vy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728747AbgEKJIV (ORCPT ); Mon, 11 May 2020 05:08:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45822 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726287AbgEKJIV (ORCPT ); Mon, 11 May 2020 05:08:21 -0400 Received: from mail-wr1-x441.google.com (mail-wr1-x441.google.com [IPv6:2a00:1450:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3EF2C061A0C for ; Mon, 11 May 2020 02:08:19 -0700 (PDT) Received: by mail-wr1-x441.google.com with SMTP id w7so9914280wre.13 for ; Mon, 11 May 2020 02:08:19 -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=rNORn63xqMXkBEqaVD2YWfy0SAq9m0rRouvmymHM0XM=; b=eDGPh8VyzS6siQjHoSre664uGN1zMMOyXQXBHZWeTx8ymioipQEeWpUSrNWs6VCtr7 z+LleB5T7uyikm/9o9q6Wd38c1UPyiH1d9Q4XWq6JOJPQbeh2mNx8wCjVUUQaEwSO+7G FJZpGFFn4+3PjiBd3KMLXJHs4X23oWEXW6ciY= 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=rNORn63xqMXkBEqaVD2YWfy0SAq9m0rRouvmymHM0XM=; b=mAw5ZjY0oTKtvzZWPk6R/s8qy5jVfHvg4vnoKx5haMjgN3sKttCNoRmXoSlTVyYlex sGeOiqloGtHa8yaFewrbn8bz79fERaAN8zlUu2A3wT8Vjbx2z9sLqxLZjtDO8JYZ9FSD blmgpDIr5ij1wNvisrOhZWSWn0xWlVvIU1LRdZc61qTHqAv2oKR0tOJzmYtkT6ySdMtv e+3Ni5TY0i6NVDPCy3RFceYRenkk8oWrnmevmnncrXZhv6rjVGOlh2i0jZZN984Tk6k7 LPmbd6fceT/3D9ZXg4cBObPbdvzr6hwXQ51ll6WYNmb6min+eKGGcD7+GCxFQ2iwLj+A c7xw== X-Gm-Message-State: AGi0PuZpe3LntYySiEmbrE/RbRaBjxEL/4Wu2xXYoEoql68131XAG9F2 Z/RvoockuEqNeiaehm4SPXqhvRN/Zm0= X-Google-Smtp-Source: APiQypKgLydNuiou6XiVQ+N9uLYeVHZFpWaev44LH0qc8jQLw5LCNKmpmUYvrOtM/kMk/On2bv4dlA== X-Received: by 2002:adf:f5cb:: with SMTP id k11mr17790975wrp.300.1589188097101; Mon, 11 May 2020 02:08:17 -0700 (PDT) Received: from cloudflare.com ([2a02:a310:c262:aa00:b35e:8938:2c2a:ba8b]) by smtp.gmail.com with ESMTPSA id t71sm27141441wmt.31.2020.05.11.02.08.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 May 2020 02:08:16 -0700 (PDT) References: <20200506125514.1020829-1-jakub@cloudflare.com> <20200506125514.1020829-3-jakub@cloudflare.com> <20200508070638.pqe73q4v3paxpkq5@kafai-mbp.dhcp.thefacebook.com> <87a72ivh6t.fsf@cloudflare.com> <20200508183928.ofudkphlb3vgpute@kafai-mbp.dhcp.thefacebook.com> User-agent: mu4e 1.1.0; emacs 26.3 From: Jakub Sitnicki To: Martin KaFai Lau Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, dccp@vger.kernel.org, kernel-team@cloudflare.com, Alexei Starovoitov , "Daniel Borkmann" , "David S. Miller" , Eric Dumazet , Gerrit Renker , Jakub Kicinski , Marek Majkowski , Lorenz Bauer Subject: Re: [PATCH bpf-next 02/17] bpf: Introduce SK_LOOKUP program type with a dedicated attach point In-reply-to: <20200508183928.ofudkphlb3vgpute@kafai-mbp.dhcp.thefacebook.com> Date: Mon, 11 May 2020 11:08:15 +0200 Message-ID: <877dxivny8.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, May 08, 2020 at 08:39 PM CEST, Martin KaFai Lau wrote: > On Fri, May 08, 2020 at 12:45:14PM +0200, Jakub Sitnicki wrote: >> On Fri, May 08, 2020 at 09:06 AM CEST, Martin KaFai Lau wrote: >> > On Wed, May 06, 2020 at 02:54:58PM +0200, Jakub Sitnicki wrote: [...] >> >> + return -ESOCKTNOSUPPORT; >> >> + >> >> + /* Check if socket is suitable for packet L3/L4 protocol */ >> >> + if (sk->sk_protocol != ctx->protocol) >> >> + return -EPROTOTYPE; >> >> + if (sk->sk_family != ctx->family && >> >> + (sk->sk_family == AF_INET || ipv6_only_sock(sk))) >> >> + return -EAFNOSUPPORT; >> >> + >> >> + /* Select socket as lookup result */ >> >> + ctx->selected_sk = sk; >> > Could sk be a TCP_ESTABLISHED sk? >> >> Yes, and what's worse, it could be ref-counted. This is a bug. I should >> be rejecting ref counted sockets here. > Agree. ref-counted (i.e. checking rcu protected or not) is the right check > here. > > An unrelated quick thought, it may still be fine for the > TCP_ESTABLISHED tcp_sk returned from sock_map because of the > "call_rcu(&psock->rcu, sk_psock_destroy);" in sk_psock_drop(). > I was more thinking about in the future, what if this helper can take > other sk not coming from sock_map. I see, psock holds a sock reference and will not release it until a full grace period has elapsed. Even if holding a ref wasn't a problem, I'm not sure if returning a TCP_ESTABLISHED socket wouldn't trip up callers of inet_lookup_listener (tcp_v4_rcv and nf_tproxy_handle_time_wait4), that look for a listener when processing a SYN to TIME_WAIT socket.