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 74BC2C636CC for ; Tue, 7 Feb 2023 10:43:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229942AbjBGKny (ORCPT ); Tue, 7 Feb 2023 05:43:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45560 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230353AbjBGKnx (ORCPT ); Tue, 7 Feb 2023 05:43:53 -0500 Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C85B57D9F for ; Tue, 7 Feb 2023 02:43:31 -0800 (PST) Date: Tue, 7 Feb 2023 11:43:28 +0100 From: Pablo Neira Ayuso To: Phil Sutter , Florian Westphal , netfilter-devel@vger.kernel.org Subject: Re: [nf-next PATCH v2] netfilter: nf_tables: Introduce NFTA_RULE_ACTUAL_EXPR Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Mon, Feb 06, 2023 at 10:52:29AM +0100, Pablo Neira Ayuso wrote: > On Sat, Feb 04, 2023 at 10:00:25PM +0100, Phil Sutter wrote: > > On Sat, Feb 04, 2023 at 10:41:37AM +0100, Pablo Neira Ayuso wrote: > > > On Fri, Feb 03, 2023 at 05:21:29PM +0100, Phil Sutter wrote: > > > [...] > > > > On Fri, Feb 03, 2023 at 04:32:01PM +0100, Pablo Neira Ayuso wrote: > > > [...] > > > > > I also wonder if this might cause problems with nftables and implicit > > > > > sets, they are bound to one single lookup expression that, when gone, > > > > > the set is released. Now you will have two expressions pointing to an > > > > > implicit set. Same thing with implicit chains. This might get tricky > > > > > with the transaction interface. > > > > > > > > While indeed two lookup expressions will refer to the same anonymous > > > > set, only one of those expressions will ever be in use. There's no way > > > > the kernel would switch between rule variants (or use both at the same > > > > time). > > > > > > OK, but control plane will reject two lookup expressions that refer to > > > the same anonymous set. > > > > Only if it sees the second expression: If NFTA_RULE_ACTUAL_EXPR is > > present, the kernel will copy the content of NFTA_RULE_EXPRESSIONS into > > a buffer pointed to by nft_rule::dump_expr. It does not inspect the > > content apart from nla_policy checking which merely ensures it's a > > nested array of elements conforming to nft_expr_policy (i.e., have a > > NAME and DATA attribute). > > > > The copied data is touched only by nf_tables_fill_rule_info() which > > copies it as-is into the skb. Later, nf_tables_rule_destroy() just frees > > the whole blob. > > > > So effectively the kernel doesn't know or care what expressions are > > contained in NFTA_RULE_EXPRESSIONS. > > Copy should work, sorry I thought you were parsing the expression again. If you are happy with this, then let's place it in nf-next?