netdev - Re: [RESEND][PATCH v4] cgroup: Use CAP_SYS_RESOURCE to allow a process to migrate other tasks between cgroups

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CALCETrUmwPaWbN_U2XAsg6Z0UGBJ=Ou7BoD09-GZFdRVT5Y-EQ@mail.gmail.com>
Date:   Tue, 6 Dec 2016 10:13:53 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Tejun Heo <tj@...nel.org>
Cc:     John Stultz <john.stultz@...aro.org>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Andy Lutomirski <luto@...nel.org>,
        Mickaël Salaün <mic@...ikod.net>,
        Daniel Mack <daniel@...que.org>,
        "David S. Miller" <davem@...emloft.net>, kafai@...com,
        Florian Westphal <fw@...len.de>,
        Harald Hoyer <harald@...hat.com>,
        Network Development <netdev@...r.kernel.org>,
        Sargun Dhillon <sargun@...gun.me>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Li Zefan <lizefan@...wei.com>,
        Jonathan Corbet <corbet@....net>,
        "open list:CONTROL GROUP (CGROUP)" <cgroups@...r.kernel.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        Rom Lemarchand <romlem@...roid.com>,
        Colin Cross <ccross@...roid.com>,
        Dmitry Shmidt <dimitrysh@...gle.com>,
        Todd Kjos <tkjos@...gle.com>,
        Christian Poetzsch <christian.potzsch@...tec.com>,
        Amit Pundir <amit.pundir@...aro.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Kees Cook <keescook@...omium.org>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Linux API <linux-api@...r.kernel.org>
Subject: Re: [RESEND][PATCH v4] cgroup: Use CAP_SYS_RESOURCE to allow a
 process to migrate other tasks between cgroups

On Tue, Dec 6, 2016 at 10:12 AM, Tejun Heo <tj@...nel.org> wrote:
> Hello,
>
> On Tue, Dec 06, 2016 at 09:01:17AM -0800, Andy Lutomirski wrote:
>> How would one be granted the right to move processes around in one's
>> own subtree?
>
> Through expicit delegation - chowning of the directory and
> cgroup.procs file.
>
>> Are you imagining that, if you're in /a/b and you want to move a
>> process that's currently in /a/b/c to /a/b/d then you're allowed to
>> because the target process is in your tree?  If so, I doubt this has
>> the security properties you want -- namely, if you can cooperate with
>> anyone in /, even if they're unprivileged, you can break it.
>
> Delegation is an explicit operation and reflected in the ownership of
> the subdirectories and cgroup interface files in them.  The
> subhierarchy containment is achieved by requiring the user who's
> trying to migrate a process to have write perm on cgroup.procs on the
> common ancestor of the source and target in addition to the target.

OK, I see what you're doing.  That's interesting.