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 0F468EB64D9 for ; Tue, 27 Jun 2023 11:13:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230315AbjF0LNB (ORCPT ); Tue, 27 Jun 2023 07:13:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229804AbjF0LNA (ORCPT ); Tue, 27 Jun 2023 07:13:00 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E08181FF3; Tue, 27 Jun 2023 04:12:58 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1qE6cq-0003Sm-6H; Tue, 27 Jun 2023 13:12:48 +0200 Date: Tue, 27 Jun 2023 13:12:48 +0200 From: Florian Westphal To: Daniel Xu Cc: daniel@iogearbox.net, edumazet@google.com, kuba@kernel.org, fw@strlen.de, pabeni@redhat.com, pablo@netfilter.org, andrii@kernel.org, davem@davemloft.net, ast@kernel.org, kadlec@netfilter.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, dsahern@kernel.org Subject: Re: [PATCH bpf-next 4/7] netfilter: bpf: Support BPF_F_NETFILTER_IP_DEFRAG in netfilter link Message-ID: <20230627111248.GH3207@breakpoint.cc> References: <242c66138bf4ec8aa26b29d736fb48242b4164ce.1687819413.git.dxu@dxuuu.xyz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <242c66138bf4ec8aa26b29d736fb48242b4164ce.1687819413.git.dxu@dxuuu.xyz> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Daniel Xu wrote: > +static int bpf_nf_enable_defrag(struct bpf_nf_link *link) > +{ > + int err; > + > + switch (link->hook_ops.pf) { > +#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) > + case NFPROTO_IPV4: > + const struct nf_defrag_v4_hook *v4_hook; > + > + err = request_module("nf_defrag_ipv4"); > + if (err) > + return err; > + > + rcu_read_lock(); > + v4_hook = rcu_dereference(nf_defrag_v4_hook); > + err = v4_hook->enable(link->net); > + rcu_read_unlock(); I'd reverse this, first try rcu_dereference(), then modprobe if thats returned NULL. > +static void bpf_nf_disable_defrag(struct bpf_nf_link *link) > +{ > + switch (link->hook_ops.pf) { > +#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) > + case NFPROTO_IPV4: > + const struct nf_defrag_v4_hook *v4_hook; > + > + rcu_read_lock(); > + v4_hook = rcu_dereference(nf_defrag_v4_hook); > + v4_hook->disable(link->net); > + rcu_read_unlock(); if (v4_hook) v4_hook->disable() Else we get trouble on manual 'rmmod'. > + /* make sure conntrack confirm is always last */ > + prio = attr->link_create.netfilter.priority; > + if (prio == NF_IP_PRI_FIRST) > + return -ERANGE; /* sabotage_in and other warts */ > + else if (prio == NF_IP_PRI_LAST) > + return -ERANGE; /* e.g. conntrack confirm */ > + else if ((attr->link_create.netfilter.flags & BPF_F_NETFILTER_IP_DEFRAG) && > + (prio > NF_IP_PRI_FIRST && prio <= NF_IP_PRI_CONNTRACK_DEFRAG)) > + return -ERANGE; /* cannot use defrag if prog runs before nf_defrag */ You could elide the (prio > NF_IP_PRI_FIRST, its already handled by first conditional. Otherwise this looks good to me.