From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net 0/2] net: diag: fix a potential security issue Date: Fri, 20 Oct 2017 23:18:04 -0700 Message-ID: References: <20171021.022737.1906342496133825805.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: David Miller , network dev , Marcelo Ricardo Leitner , Sabrina Dubroca To: Xin Long Return-path: Received: from mail-yw0-f194.google.com ([209.85.161.194]:48172 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751104AbdJUGSG (ORCPT ); Sat, 21 Oct 2017 02:18:06 -0400 Received: by mail-yw0-f194.google.com with SMTP id q1so8124295ywh.5 for ; Fri, 20 Oct 2017 23:18:06 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Oct 20, 2017 at 11:06 PM, Xin Long wrote: > > > On Sat, Oct 21, 2017 at 9:27 AM, David Miller wrote: >> >> From: Xin Long >> Date: Thu, 19 Oct 2017 15:32:23 +0800 >> >> > This patch is to void the potential security issue that the family >> > or protocol modules are autoloaded when requesting _diag module by >> > not requesting _diag module if the family or protocol is not added >> > or registered in sock_diag and inet_diag. >> > >> > As the repost of the patch '[PATCH net] sock_diag: request _diag >> > module only when the family or proto has been registered', this >> > patchset fixes the compiling errors when INET is not set, and >> > also split into two patches to make it clear to review. >> >> This makes no sense to me. >> >> Any user can just open a socket() in the appropriate protocol >> family to cause the module to be loaded. >> >> If someone wants modules to not be loaded, block them using >> traditional module loading infrastructure mechanisms. Or >> don't load the module at all. >> >> Sorry I am not applying this. > > Hi David, > > I'm still thinking it's not good after 'ss', sctp, dccp, > af_packet ... are just loaded, in which case, no one actually > open any socket with these family or proto. > > I talked with Marcelo before, one scenario as he said: > > Imagine a customer generates a sosreport on their system, and > with that, it loads sctp module. From then on, if their firewall > doesn't block incoming packets for sctp, they may be prone to some > remotely triggerable issue on sctp code, without even actually using > sctp. For that reason, we have disabled autoloading of SCTP. ( removing the MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-132"); MODULE_ALIAS("net-pf-" __stringify(PF_INET6) "-proto-132"); ) root must modprobe the module before it is accessible. However inet_diag is a way to have the module loaded anyway. This is why I like your patch Xin. David is only saying that your patch alone is not enough to prevent a user to use socket() to autoload SCTP.