From mboxrd@z Thu Jan  1 00:00:00 1970
From: Miklos Szeredi <miklos@szeredi.hu>
Subject: Re: [PATCH v5 3/4] fuse: Restrict allow_other to the superblock's
 namespace or a descendant
Date: Tue, 11 Nov 2014 16:27:37 +0100
Message-ID: <20141111152737.GE333@tucsk>
References: <1414013060-137148-1-git-send-email-seth.forshee@canonical.com>
 <1414013060-137148-4-git-send-email-seth.forshee@canonical.com>
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Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	"Serge H. Hallyn" <serge.hallyn@ubuntu.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Michael j Theall <mtheall@us.ibm.com>,
	fuse-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
To: Seth Forshee <seth.forshee@canonical.com>
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On Wed, Oct 22, 2014 at 04:24:19PM -0500, Seth Forshee wrote:
> Unprivileged users are normally restricted from mounting with the
> allow_other option by system policy, but this could be bypassed
> for a mount done with user namespace root permissions. In such
> cases allow_oth er should not allow users outside the userns
> to access the mount as doing so would give the unprivileged user
> the ability to manipulate processes it would otherwise be unable
> to manipulate. Therefore access with allow_other should be
> restricted to users in the userns as the superblock or a
> descendant of that namespace.

Fine.

But aren't this kind of thing supposed to be prevented anyway by having private
mount namespace coupled with the pid-user-whatever namespace?

It seems like being a bit too careful (not to say that that's a bad thing).

Thanks,
Miklos