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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 C3EA2C10F14 for ; Thu, 10 Oct 2019 20:21:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8F291206B6 for ; Thu, 10 Oct 2019 20:21:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726696AbfJJUVb (ORCPT ); Thu, 10 Oct 2019 16:21:31 -0400 Received: from mx2.suse.de ([195.135.220.15]:59574 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726533AbfJJUVb (ORCPT ); Thu, 10 Oct 2019 16:21:31 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2CE76AC6E; Thu, 10 Oct 2019 20:21:29 +0000 (UTC) Received: by unicorn.suse.cz (Postfix, from userid 1000) id CAA94E378C; Thu, 10 Oct 2019 22:21:28 +0200 (CEST) Date: Thu, 10 Oct 2019 22:21:28 +0200 From: Michal Kubecek To: Jakub Kicinski Cc: "David S. Miller" , Jiri Pirko , Johannes Berg , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v2] genetlink: do not parse attributes for families with zero maxattr Message-ID: <20191010202128.GJ22163@unicorn.suse.cz> References: <20191010103402.36408E378C@unicorn.suse.cz> <20191010102102.3bc8515d@cakuba.netronome.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191010102102.3bc8515d@cakuba.netronome.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 10, 2019 at 10:21:02AM -0700, Jakub Kicinski wrote: > On Thu, 10 Oct 2019 12:34:02 +0200 (CEST), Michal Kubecek wrote: > > Commit c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing > > to a separate function") moved attribute buffer allocation and attribute > > parsing from genl_family_rcv_msg_doit() into a separate function > > genl_family_rcv_msg_attrs_parse() which, unlike the previous code, calls > > __nlmsg_parse() even if family->maxattr is 0 (i.e. the family does its own > > parsing). The parser error is ignored and does not propagate out of > > genl_family_rcv_msg_attrs_parse() but an error message ("Unknown attribute > > type") is set in extack and if further processing generates no error or > > warning, it stays there and is interpreted as a warning by userspace. > > > > Dumpit requests are not affected as genl_family_rcv_msg_dumpit() bypasses > > the call of genl_family_rcv_msg_doit() if family->maxattr is zero. Do the > > same also in genl_family_rcv_msg_doit(). > > > > Fixes: c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing to a separate function") > > Signed-off-by: Michal Kubecek > > --- > > net/netlink/genetlink.c | 9 +++++---- > > 1 file changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c > > index ecc2bd3e73e4..1f14e55ad3ad 100644 > > --- a/net/netlink/genetlink.c > > +++ b/net/netlink/genetlink.c > > @@ -639,21 +639,23 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family, > > const struct genl_ops *ops, > > int hdrlen, struct net *net) > > { > > - struct nlattr **attrbuf; > > + struct nlattr **attrbuf = NULL; > > struct genl_info info; > > int err; > > > > if (!ops->doit) > > return -EOPNOTSUPP; > > > > + if (!family->maxattr) > > + goto no_attrs; > > attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack, > > ops, hdrlen, > > GENL_DONT_VALIDATE_STRICT, > > - family->maxattr && > > family->parallel_ops); > > if (IS_ERR(attrbuf)) > > return PTR_ERR(attrbuf); > > > > +no_attrs: > > The use of a goto statement as a replacement for an if is making me > uncomfortable. I used instead of a simple if because (1) it's what the dumpit code does and (2) the function call arguments are already quite pressed to the 80-character barrier. > Looks like both callers of genl_family_rcv_msg_attrs_parse() jump > around it if !family->maxattr and then check the result with IS_ERR(). > > Would it not make more sense to have genl_family_rcv_msg_attrs_parse() > return NULL if !family->maxattr? This sounds like a good solution. I'll check again in the morning and send v3. Michal