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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS 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 2EFA6C43219 for ; Thu, 2 May 2019 12:55:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 015EB20449 for ; Thu, 2 May 2019 12:55:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726515AbfEBMzC (ORCPT ); Thu, 2 May 2019 08:55:02 -0400 Received: from s3.sipsolutions.net ([144.76.43.62]:55590 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726282AbfEBMzC (ORCPT ); Thu, 2 May 2019 08:55:02 -0400 Received: by sipsolutions.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1hMBEn-000103-Sz; Thu, 02 May 2019 14:54:58 +0200 Message-ID: <3e8291cb2491e9a1830afdb903ed2c52e9f7475c.camel@sipsolutions.net> Subject: Re: [PATCH net-next 3/3] netlink: add validation of NLA_F_NESTED flag From: Johannes Berg To: Michal Kubecek , "David S. Miller" Cc: "netdev@vger.kernel.org" , David Ahern , "linux-kernel@vger.kernel.org" Date: Thu, 02 May 2019 14:54:56 +0200 In-Reply-To: <75a0887b3eb70005c272685d8ef9a712f37d7a54.1556798793.git.mkubecek@suse.cz> References: <75a0887b3eb70005c272685d8ef9a712f37d7a54.1556798793.git.mkubecek@suse.cz> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-2.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2019-05-02 at 12:48 +0000, Michal Kubecek wrote: > Add new validation flag NL_VALIDATE_NESTED which adds three consistency > checks of NLA_F_NESTED_FLAG: > > - the flag is set on attributes with NLA_NESTED{,_ARRAY} policy > - the flag is not set on attributes with other policies except NLA_UNSPEC > - the flag is set on attribute passed to nla_parse_nested() Looks good to me! > @@ -415,7 +418,8 @@ enum netlink_validation { > #define NL_VALIDATE_STRICT (NL_VALIDATE_TRAILING |\ > NL_VALIDATE_MAXTYPE |\ > NL_VALIDATE_UNSPEC |\ > - NL_VALIDATE_STRICT_ATTRS) > + NL_VALIDATE_STRICT_ATTRS |\ > + NL_VALIDATE_NESTED) This is fine _right now_, but in general we cannot keep adding here after the next release :-) > int netlink_rcv_skb(struct sk_buff *skb, > int (*cb)(struct sk_buff *, struct nlmsghdr *, > @@ -1132,6 +1136,10 @@ static inline int nla_parse_nested(struct nlattr *tb[], int maxtype, > const struct nla_policy *policy, > struct netlink_ext_ack *extack) > { > + if (!(nla->nla_type & NLA_F_NESTED)) { > + NL_SET_ERR_MSG_ATTR(extack, nla, "nested attribute expected"); Maybe reword that to say "NLA_F_NESTED is missing" or so? The "nested attribute expected" could result in a lot of headscratching (without looking at the code) because it looks nested if you do nla_nest_start() etc. > + return -EINVAL; > + } > return __nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy, > NL_VALIDATE_STRICT, extack); I'd probably put a blank line there but ymmv. > } > diff --git a/lib/nlattr.c b/lib/nlattr.c > index adc919b32bf9..92da65cb6637 100644 > --- a/lib/nlattr.c > +++ b/lib/nlattr.c > @@ -184,6 +184,21 @@ static int validate_nla(const struct nlattr *nla, int maxtype, > } > } > > + if (validate & NL_VALIDATE_NESTED) { > + if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) && > + !(nla->nla_type & NLA_F_NESTED)) { > + NL_SET_ERR_MSG_ATTR(extack, nla, > + "nested attribute expected"); > + return -EINVAL; > + } > + if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY && > + pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) { > + NL_SET_ERR_MSG_ATTR(extack, nla, > + "nested attribute not expected"); > + return -EINVAL; Same comment here wrt. the messages, I think they should more explicitly refer to the flag. johannes (PS: if you CC me on this address I generally can respond quicker)