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Date: Fri, 25 Sep 2015 07:49:24 -0500
From: Seth Forshee <seth.forshee@canonical.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
 Serge Hallyn <serge.hallyn@canonical.com>,
 James Morris <james.l.morris@oracle.com>,
 "Serge E. Hallyn" <serge@hallyn.com>,
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 linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov,
 linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org
Subject: Re: [PATCH v4 4/7] fs: Limit file caps to the user namespace of the
 super block
Message-ID: <20150925124924.GB104990@ubuntu-hedt>
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On Thu, Sep 24, 2015 at 04:59:35PM -0500, Eric W. Biederman wrote:
> Seth Forshee <seth.forshee@canonical.com> writes:
> 
> > Capability sets attached to files must be ignored except in the
> > user namespaces where the mounter is privileged, i.e. s_user_ns
> > and its descendants. Otherwise a vector exists for gaining
> > privileges in namespaces where a user is not already privileged.
> >
> > Add a new helper function, in_user_ns(), to test whether a user
> > namespace is the same as or a descendant of another namespace.
> > Use this helper to determine whether a file's capability set
> > should be applied to the caps constructed during exec.
> 
> No issues with this but given that we always pass current_user_ns()
> we may want to simplify the users of in_user_ns by renaming it
> current_in_user_ns() and hard codeing current_user_ns().

Sure, if that's what you prefer then I'll change it.

Seth