linux-kernel - Re: [PATCH v12 8/8] cgroup: implement the PIDs subsystem

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: <CAOviyaiwGQZbA8w_TV0wXF7JaQK1LHGn8BC40R7ARR+mHHQf=Q@mail.gmail.com>
Date:	Tue, 19 May 2015 23:43:21 +1000
From:	Aleksa Sarai <cyphar@...har.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Peter Zijlstra <peterz@...radead.org>, Tejun Heo <tj@...nel.org>,
	lizefan@...wei.com, mingo@...hat.com, richard@....at,
	Frédéric Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org
Subject: Re: [PATCH v12 8/8] cgroup: implement the PIDs subsystem

>> >> However, it should be noted that organisational operations (adding and
>> >> removing tasks from a PIDs hierarchy) will *not* be prevented.
>> >
>> > This is how you spell: broken controller.
>>
>> This has been discussed before. Organisational operations (i.e.
>> attaching to a cgroup) are not to be blocked by a cgroup controller in
>> the unified hierarchy. You simply can't escape out of a parent
>> cgroup's limit through attaching to a child cgroup (because you will
>> attach either before the fork checks against the cgroup [in which case
>> the child's limit is followed -- which means you also follow the
>> parent's limit] or after it checks [which means you'll hit the
>> parent's limit and won't be able to fork]).
>
> That's complete and utter nonsense. What has the parent limit to do
> with the overflow of the child limit?
>
> parent:  limit 100   usecnt 80
> child:   limit 10    usecnt 10
>
> So moving anything into child is violating the constraints and has to
> be refused. Anything else is just dirty hackery.

Whoops. Yes, you're completely right. All right, I'll fix up the
patchset in a few days.

--
Aleksa Sarai (cyphar)
www.cyphar.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/