linux-kernel - Re: [RFC] [PATCH -mm] oom_kill: remove uid==0 checks

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Message-ID: <20071221144606.GC27197@sergelap.austin.ibm.com>
Date:	Fri, 21 Dec 2007 08:46:06 -0600
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Andrew Morgan <morgan@...nel.org>, serue@...ibm.com,
	containers@...ts.osdl.org, linux-kernel@...r.kernel.org,
	minslinux-mm@...ck.org
Subject: Re: [RFC] [PATCH -mm] oom_kill: remove uid==0 checks

Quoting Andrew Morton (akpm@...ux-foundation.org):
> On Wed, 12 Dec 2007 15:06:17 -0800
> Andrew Morgan <morgan@...nel.org> wrote:
> 
> > Serge E. Hallyn wrote:
> > > Andrew, I've cc:d you here bc in doing this patch I noticed that your
> > > 64-bit capabilities patch switched this code from an explicit check
> > > of cap_t(p->cap_effective) to using __capable().  That means that
> > > now being glossed over by the oom killer means PF_SUPERPRIV will
> > > be set.  Is that intentional?
> > 
> > Yes, I switched the check because the old one didn't work with the new
> > capability representation.
> > 
> > However, I had not thought this aspect of this replacement through. At
> > the time, it seemed obvious but in this case it actually depends on
> > whether you think using privilege (PF_SUPERPRIV) means "benefited from
> > privilege", or "successfully completed a privileged operation".
> > 
> > I suspect, in this case, the correct thing to do is add the equivalent of:
> > 
> > #define CAPABLE_PROBE_ONLY(a,b)   (!security_capable(a,b))
> > 
> > and use that in the code in question. That is, return to the old
> > behavior in a way that will not break if we ever need to add more bits.

Oh, I'm sorry - Andrew Morgan, I somehow read that email to say you were
going to post such a patch, and let it fall off my todo list.  Should I
go ahead and post a patch or do you have one ready?

> I'm struggling to understand whether the above was an ack, a nack or a
> quack.
> 
> > Thanks for finding this.
> 
> >From that I'll assume ack ;)

It actually wasn't an ack of my patch.  But I'm not sure where to look
for that.

thanks,
-serge
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