From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Lutomirski Subject: Re: [PATCH 2/2] net: Implement SO_PEERCGROUP Date: Wed, 12 Mar 2014 14:00:28 -0700 Message-ID: <5320CAEC.6030008@amacapital.net> References: <1394657163-7472-1-git-send-email-vgoyal@redhat.com> <1394657163-7472-3-git-send-email-vgoyal@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: ssorce-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, jkaluza-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, lpoetter-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, kay-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org To: Vivek Goyal , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Return-path: In-Reply-To: <1394657163-7472-3-git-send-email-vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On 03/12/2014 01:46 PM, Vivek Goyal wrote: > Implement SO_PEERCGROUP along the lines of SO_PEERCRED. This returns the > cgroup of first mounted hierarchy of the task. For the case of client, > it represents the cgroup of client at the time of opening the connection. > After that client cgroup might change. Even if people decide that sending cgroups over a unix socket is a good idea, this API has my NAK in the strongest possible sense, for whatever my NAK is worth. IMO SO_PEERCRED is a disaster. Calling send(2) or write(2) should *never* imply the use of a credential. A program should always have to *explicitly* request use of a credential. What you want is SCM_CGROUP. (I've found privilege escalations before based on this observation, and I suspect I'll find them again.) Note that I think that you really want SCM_SOMETHING_ELSE and not SCM_CGROUP, but I don't know what the use case is yet. --Andy