linux-kernel - Re: [PATCH 07/44] kdbus: Fix comment on translation of caps between namespaces

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Message-ID: <20151009073422.GB2189@localhost.localdomain>
Date:	Fri, 9 Oct 2015 10:34:22 +0300
From:	Sergei Zviagintsev <sergei@...v.net>
To:	Hillf Danton <hillf.zj@...baba-inc.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	'Daniel Mack' <daniel@...que.org>,
	'David Herrmann' <dh.herrmann@...glemail.com>,
	'Djalal Harouni' <tixxdz@...ndz.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 07/44] kdbus: Fix comment on translation of caps between
 namespaces

Hi,

On Fri, Oct 09, 2015 at 11:43:22AM +0800, Hillf Danton wrote:
> > @@ -730,15 +730,21 @@ static void kdbus_meta_export_caps(struct kdbus_meta_caps *out,
> > 
> >  	/*
> >  	 * This translates the effective capabilities of 'cred' into the given
> > -	 * user-namespace. If the given user-namespace is a child-namespace of
> > -	 * the user-namespace of 'cred', the mask can be copied verbatim. If
> > -	 * not, the mask is cleared.
> > -	 * There's one exception: If 'cred' is the owner of any user-namespace
> > -	 * in the path between the given user-namespace and the user-namespace
> > -	 * of 'cred', then it has all effective capabilities set. This means,
> > -	 * the user who created a user-namespace always has all effective
> > -	 * capabilities in any child namespaces. Note that this is based on the
> > -	 * uid of the namespace creator, not the task hierarchy.
> > +	 * user namespace according to the following rules:
> > +	 *
> > +	 * - If 'cred' is a member of the given user namespace or any of its
> > +	 *   parent user namespaces, the mask is copied verbatim. That is, if
> 
> Clearer/Better if "if not, the mask is cleared." is reserved.

Indeed, thanks!

> 
> > +	 *   a process has a capability in a user namespace, then it has it in
> > +	 *   all child user namespaces too.
> > +	 *
> > +	 * - If the effective UID of 'cred' matches the owner of the given user
> > +	 *   namespace or any of its parent user namespaces and 'cred' itself
> > +	 *   resides in the parent of that user namespace which it owns, then
> > +	 *   it has all effective capabilities set. This means that the user
> > +	 *   who created a user namespace always has all effective capabilities
> > +	 *   in all child namespaces while staying in the parent of the user
> > +	 *   namespace which it owns. Note that this is based on the UID of the
> > +	 *   namespace creator, not the task hierarchy.
> >  	 */
> >  	for (iter = user_ns; iter; iter = iter->parent) {
> >  		if (iter == cred->user_ns) {
> > --
> > 1.8.3.1
> > 
> 
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