From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: [PATCH 2/3] netfilter: nf_tables: check for overflow of rule dlen field Date: Thu, 5 Mar 2015 18:11:50 +0100 Message-ID: <20150305171150.GA7275@salvia> References: <1425413060-6187-1-git-send-email-kaber@trash.net> <1425413060-6187-3-git-send-email-kaber@trash.net> <20150305163127.GA6878@salvia> <20150305163122.GW29092@acer.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netfilter-devel@vger.kernel.org To: Patrick McHardy Return-path: Received: from mail.us.es ([193.147.175.20]:57955 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757572AbbCERIJ (ORCPT ); Thu, 5 Mar 2015 12:08:09 -0500 Content-Disposition: inline In-Reply-To: <20150305163122.GW29092@acer.localdomain> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Thu, Mar 05, 2015 at 04:31:22PM +0000, Patrick McHardy wrote: > On 05.03, Pablo Neira Ayuso wrote: > > On Tue, Mar 03, 2015 at 08:04:19PM +0000, Patrick McHardy wrote: > > > Check that the space required for the expressions doesn't exceed the > > > size of the dlen field, which would lead to the iterators crashing. > > > > > > Signed-off-by: Patrick McHardy > > > --- > > > net/netfilter/nf_tables_api.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c > > > index 6fb532b..7baafd5 100644 > > > --- a/net/netfilter/nf_tables_api.c > > > +++ b/net/netfilter/nf_tables_api.c > > > @@ -1968,6 +1968,10 @@ static int nf_tables_newrule(struct sock *nlsk, struct sk_buff *skb, > > > n++; > > > } > > > } > > > + /* Check for overflow of dlen field */ > > > + err = -EFBIG; > > > > Should we use -EOVERFLOW instead as we use in other nf_tables spots? > > > > The error in userspace will be: "Value too large for defined data type". > > I think the difference here is that we don't use a userspace provided > value but overflow because of the size of kernel internal structures and > the data type limit. OK, we also have it when we pass too large amount of data for a register IIRC. > I don't have any strong feelings either way, but I think its different > from the cases where we use EOVERFLOW so far. I don't have any strong opinion, just asking. You know we shouldn't change this afterwards. Let me know.