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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 DAC33C433DF for ; Fri, 22 May 2020 00:26:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A32A12072C for ; Fri, 22 May 2020 00:26:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726853AbgEVA0F (ORCPT ); Thu, 21 May 2020 20:26:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35738 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726650AbgEVA0F (ORCPT ); Thu, 21 May 2020 20:26:05 -0400 Received: from shards.monkeyblade.net (shards.monkeyblade.net [IPv6:2620:137:e000::1:9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEE74C061A0E for ; Thu, 21 May 2020 17:26:05 -0700 (PDT) Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 69615120ED486; Thu, 21 May 2020 17:26:05 -0700 (PDT) Date: Thu, 21 May 2020 17:26:04 -0700 (PDT) Message-Id: <20200521.172604.648069177650832955.davem@davemloft.net> To: sd@queasysnail.net Cc: netdev@vger.kernel.org, dsahern@gmail.com Subject: Re: [PATCH net] net: don't return invalid table id error when we fall back to PF_UNSPEC From: David Miller In-Reply-To: References: X-Mailer: Mew version 6.8 on Emacs 26.3 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 21 May 2020 17:26:05 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Sabrina Dubroca Date: Wed, 20 May 2020 11:15:46 +0200 > In case we can't find a ->dumpit callback for the requested > (family,type) pair, we fall back to (PF_UNSPEC,type). In effect, we're > in the same situation as if userspace had requested a PF_UNSPEC > dump. For RTM_GETROUTE, that handler is rtnl_dump_all, which calls all > the registered RTM_GETROUTE handlers. > > The requested table id may or may not exist for all of those > families. commit ae677bbb4441 ("net: Don't return invalid table id > error when dumping all families") fixed the problem when userspace > explicitly requests a PF_UNSPEC dump, but missed the fallback case. > > For example, when we pass ipv6.disable=1 to a kernel with > CONFIG_IP_MROUTE=y and CONFIG_IP_MROUTE_MULTIPLE_TABLES=y, > the (PF_INET6, RTM_GETROUTE) handler isn't registered, so we end up in > rtnl_dump_all, and listing IPv6 routes will unexpectedly print: > > # ip -6 r > Error: ipv4: MR table does not exist. > Dump terminated > > commit ae677bbb4441 introduced the dump_all_families variable, which > gets set when userspace requests a PF_UNSPEC dump. However, we can't > simply set the family to PF_UNSPEC in rtnetlink_rcv_msg in the > fallback case to get dump_all_families == true, because some messages > types (for example RTM_GETRULE and RTM_GETNEIGH) only register the > PF_UNSPEC handler and use the family to filter in the kernel what is > dumped to userspace. We would then export more entries, that userspace > would have to filter. iproute does that, but other programs may not. > > Instead, this patch removes dump_all_families and updates the > RTM_GETROUTE handlers to check if the family that is being dumped is > their own. When it's not, which covers both the intentional PF_UNSPEC > dumps (as dump_all_families did) and the fallback case, ignore the > missing table id error. > > Fixes: cb167893f41e ("net: Plumb support for filtering ipv4 and ipv6 multicast route dumps") > Signed-off-by: Sabrina Dubroca Applied and queued up for -stable, thank you.