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Date: Tue, 20 Sep 2011 08:33:49 -0500
From: "Serge E. Hallyn" <serge.hallyn@canonical.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: lkml <linux-kernel@vger.kernel.org>, richard@nod.at,
        Andrew Morton <akpm@google.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>, Tejun Heo <tj@kernel.org>,
        serge@hallyn.com
Subject: Re: [PATCH] user namespace: usb: make usb urbs user namespace aware
Message-ID: <20110920133349.GA4506@sergelap>
References: <20110919214531.GA18085@sergelap>
 <20110919214700.GA22300@sergelap>
 <20110920131738.GA29852@redhat.com>
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Quoting Oleg Nesterov (oleg@redhat.com):
> On 09/19, Serge E. Hallyn wrote:
> >
> > Add to the dev_state and alloc_async structures the user namespace
> > corresponding to the uid and euid.  Pass these to kill_pid_info_as_uid(),
> > which can then implement a proper, user-namespace-aware uid check.
> 
> IOW, we add the additional "user_namespace *" member/argument, and use
> it along with uid/euid.
> 
> I am not really sure, but can't we simplify this?
> 
> > @@ -68,6 +69,7 @@ struct dev_state {
> >  	wait_queue_head_t wait;     /* wake up if a request completed */
> >  	unsigned int discsignr;
> >  	struct pid *disc_pid;
> > +	struct user_namespace *user_ns;
> >  	uid_t disc_uid, disc_euid;
> 
> Can't we add "const struct cred *disc_cred" and kill disc_uid/disc_euid
> instead?
> 
> Then we redefine kill_pid_info_as_uid() as kill_pid_info_as_cred(...cred...),
> it can use cred->cred->uid/euid directly.
> 
> devio.c does get_cred/put_cred instead of get_user_ns/put_user_ns.
> 
> What do you think?

Yeah, just as file->f_cred does.  Sounds good.

I'll re-send both these patches with your suggestions applied.  Thanks!

-serge