linux-kernel - Re: [patch] file capabilities: Add no_file

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Message-ID: <20080827173236.2198786e@lxorguk.ukuu.org.uk>
Date:	Wed, 27 Aug 2008 17:32:36 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	David Howells <dhowells@...hat.com>
Cc:	"Serge E. Hallyn" <serue@...ibm.com>, dhowells@...hat.com,
	Andreas Gruenbacher <agruen@...e.de>,
	"Andrew G. Morgan" <morgan@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [patch] file capabilities: Add no_file_caps switch

On Wed, 27 Aug 2008 17:13:24 +0100
David Howells <dhowells@...hat.com> wrote:

> Serge E. Hallyn <serue@...ibm.com> wrote:
> 
> > (Also note that if you have such users, you'll want to ask David Howells not
> > to push the patch he has floated removing the ability to pass caps to
> > another task altogether when CONFIG_SECURITY_FILE_CAPABILITIES=n :)
> 
> Ugh.  My patch removes the ability to pass caps to another task under all
> circumstances because to do otherwise means that I have to make the kernel use
> RCU locking for a task to access its own creds.  If you want this, I'll have
> to redo all my later patches.

That gets foul in another way - bounding the worst case RCU
memory utilisation if someone is sitting doing things like while(1)
change_credentials();
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