linux-kernel - Re: MNT_DETACH and mount namespace issue

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Message-ID: <53E0062A.8030204@nod.at>
Date:	Tue, 05 Aug 2014 00:16:10 +0200
From:	Richard Weinberger <richard@....at>
To:	Ram Pai <linuxram@...ibm.com>
CC:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Christoph Hellwig <hch@...radead.org>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Jeff Mahoney <jeffm@...e.com>, sahne@...0.at,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: MNT_DETACH and mount namespace issue

Am 05.08.2014 00:10, schrieb Ram Pai:
> On Mon, Aug 04, 2014 at 11:19:35PM +0200, Richard Weinberger wrote:
>> Am 04.08.2014 18:46, schrieb Eric W. Biederman:
>>> Richard Weinberger <richard.weinberger@...il.com> writes:
>>
>> /proc is propagating into another mount namespaces that does not care.
>> This happens because systemd creates for several services a mount namespace and sets
>> the root tree to MS_SHARED.
> 
> if propagations are not needed, than set the root of the new mount
> namespace to MS_PRIVATE first and then set it to MS_SHARED.
> 
> MS_PRIVATE will delink the propagations, and MS_SHARED later will enable
> the new mounts to propagate to whoever wants them.

AFAICT this would break systemd's PrivateTmp feature. :(
They want propagation. Such that a systemd service has a private /tmp but sees freshly
mounted filesystems after setting up the namespace.

Thanks,
//richard
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