From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v2 1/2] netlink: add NLA_REJECT policy type Date: Tue, 18 Sep 2018 19:51:42 -0700 (PDT) Message-ID: <20180918.195142.1871581637054906657.davem@redhat.com> References: <20180917095729.11185-1-johannes@sipsolutions.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, marcelo.leitner@gmail.com, mkubecek@suse.cz, johannes.berg@intel.com To: johannes@sipsolutions.net Return-path: Received: from mx1.redhat.com ([209.132.183.28]:46636 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725870AbeISI12 (ORCPT ); Wed, 19 Sep 2018 04:27:28 -0400 In-Reply-To: <20180917095729.11185-1-johannes@sipsolutions.net> Sender: netdev-owner@vger.kernel.org List-ID: From: Johannes Berg Date: Mon, 17 Sep 2018 11:57:28 +0200 > From: Johannes Berg > > In some situations some netlink attributes may be used for output > only (kernel->userspace) or may be reserved for future use. It's > then helpful to be able to prevent userspace from using them in > messages sent to the kernel, since they'd otherwise be ignored and > any future will become impossible if this happens. > > Add NLA_REJECT to the policy which does nothing but reject (with > EINVAL) validation of any messages containing this attribute. > Allow for returning a specific extended ACK error message in the > validation_data pointer. > > While at it clear up the documentation a bit - the NLA_BITFIELD32 > documentation was added to the list of len field descriptions. > > Also, use NL_SET_BAD_ATTR() in one place where it's open-coded. > > The specific case I have in mind now is a shared nested attribute > containing request/response data, and it would be pointless and > potentially confusing to have userspace include response data in > the messages that actually contain a request. > > Signed-off-by: Johannes Berg > --- > v2: preserve behaviour of overwriting the extack message, with > either the generic or the specific one now Applied.