From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xin Long Subject: Re: [PATCH net 0/2] net: diag: fix a potential security issue Date: Sat, 21 Oct 2017 14:51:25 +0800 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: Eric Dumazet Return-path: Received: from mail-qt0-f193.google.com ([209.85.216.193]:52863 "EHLO mail-qt0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751146AbdJUGv1 (ORCPT ); Sat, 21 Oct 2017 02:51:27 -0400 Received: by mail-qt0-f193.google.com with SMTP id 31so20911330qtz.9 for ; Fri, 20 Oct 2017 23:51:27 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Sat, Oct 21, 2017 at 2:18 PM, Eric Dumazet wrote: > 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. Using socket() to autoload SCTP should be fine, cause users would use SCTP, no ? "ss" doesn't mean users intend to use SCTP, "ss" may make users not aware that SCTP module would be loaded, unlike socket(SCTP).