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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 416FBC432C3 for ; Thu, 14 Nov 2019 10:52:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 18F59206EF for ; Thu, 14 Nov 2019 10:52:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726369AbfKNKw0 (ORCPT ); Thu, 14 Nov 2019 05:52:26 -0500 Received: from orbyte.nwl.cc ([151.80.46.58]:52470 "EHLO orbyte.nwl.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725977AbfKNKw0 (ORCPT ); Thu, 14 Nov 2019 05:52:26 -0500 Received: from n0-1 by orbyte.nwl.cc with local (Exim 4.91) (envelope-from ) id 1iVCjh-0001mC-O1; Thu, 14 Nov 2019 11:52:25 +0100 Date: Thu, 14 Nov 2019 11:52:25 +0100 From: Phil Sutter To: Pablo Neira Ayuso Cc: netfilter-devel@vger.kernel.org Subject: Re: [nft PATCH] evaluate: Reject set references in mapping LHS Message-ID: <20191114105225.GG11663@orbyte.nwl.cc> Mail-Followup-To: Phil Sutter , Pablo Neira Ayuso , netfilter-devel@vger.kernel.org References: <20191031182124.11393-1-phil@nwl.cc> <20191112214518.tsevqoqtm5ubov3p@salvia> <20191112221827.GD11663@orbyte.nwl.cc> <20191113101050.GE11663@orbyte.nwl.cc> <20191113231022.bb7hmwqvmgm4emv7@salvia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191113231022.bb7hmwqvmgm4emv7@salvia> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Thu, Nov 14, 2019 at 12:10:22AM +0100, Pablo Neira Ayuso wrote: > On Wed, Nov 13, 2019 at 11:10:50AM +0100, Phil Sutter wrote: > > On Tue, Nov 12, 2019 at 11:18:27PM +0100, Phil Sutter wrote: > > > On Tue, Nov 12, 2019 at 10:45:18PM +0100, Pablo Neira Ayuso wrote: > > > > On Thu, Oct 31, 2019 at 07:21:24PM +0100, Phil Sutter wrote: > > > > > This wasn't explicitly caught before causing a program abort: > > > > > > > > > > | BUG: invalid range expression type set reference > > > > > | nft: expression.c:1162: range_expr_value_low: Assertion `0' failed. > > > > > | zsh: abort sudo ./install/sbin/nft add rule t c meta mark set tcp dport map '{ @s : 23 } > > > > > > > > > > With this patch in place, the error message is way more descriptive: > > > > > > > > > > | Error: Key can't be set reference > > > > > | add rule t c meta mark set tcp dport map { @s : 23 } > > > > > | ^^ > > > > > > > > I wanted to check why the parser allow for this... > > > > > > For set elements or LHS parts of map elements, there is set_lhs_expr. > > > The latter may be concat_rhs_expr or multiton_rhs_expr. concat_rhs_expr > > > eventually resolves into primary_rhs_expr which may be symbol_expr. > > > > > > BTW, it seems like from parser side, set references on map element's > > > RHS are allowed as well. > > > > > > IMHO, parser_bison.y slowly but steadily turns into a can of worms. :( > > > > On a second look, I start wondering whether symbol_expr was a wise > > choice: This thing combines variables ('$' identifier), "unidentified" > > strings and set references (AT identifier). > > > > With symbol_expr being listed in both primary_expr and primary_rhs_expr, > > set references are allowed about anywhere - even in concatenations or > > any binary operation. > > It would be probably good to restrict set references to where it makes > sense only. This is good for the grammar and we don't need to validate > all possible invalid combinations from the evaluation step. ACK! > Would you have a look or you think it's too complicated to attack this > from the parser? It's not too complicated, but I sometimes feel like turning adjuster screws on a machine I don't understand. OK, given that parser_bison.y was initially written by Patrick, you're probably in the same situation. :) Cheers, Phil