Re: [Patch 5/8] mqueue: revert bump up DFLT_*MAX

From: KOSAKI Motohiro
Date: Tue Apr 17 2012 - 23:37:34 EST


(4/17/12 11:22 PM), Serge E. Hallyn wrote:
Quoting Doug Ledford (dledford@xxxxxxxxxx):
From: KOSAKI Motohiro<kosaki.motohiro@xxxxxxxxxxxxxx>

Mqueue limitation is slightly naieve parameter likes other ipcs
because unprivileged user can consume kernel memory by using ipcs.

Thus, too aggressive raise bring us security issue. Example,
current setting allow evil unprivileged user use 256GB (= 256
* 1024 * 1024*1024) and it's enough large to system will belome
unresponsive. Don't do that.

Instead, every admin should adjust the knobs for their own systems.

Would you be terribly averse to having a higher limit in init_ipc_ns,
and the lower values by default in all child namespaces?

No, I just focused to don't create any regressions. i.e. I mainly focused
no namespace use case. And, I'm sorry, I don't think I clearly understand
recent namespace update. I'm not against any namespace enhancement. Please
only think just I don't understand neither a ipc namespace requirement nor
the code.



Sorry it sounds from the intro like you've already had quite a bit of
discussion on this...

Of course I realize the values can just be raised by distro boot
scripts...
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