linux-kernel - Re: [PATCH] sunrpc: prompt for RPCSEC_GSS_KRB5 even if NFS

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Message-ID: <20100927125404.GB6271@pengutronix.de>
Date:	Mon, 27 Sep 2010 14:54:04 +0200
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	Trond Myklebust <Trond.Myklebust@...app.com>
Cc:	linux-kernel@...r.kernel.org,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Neil Brown <neilb@...e.de>,
	"David S. Miller" <davem@...emloft.net>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	linux-nfs@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] sunrpc: prompt for RPCSEC_GSS_KRB5 even if NFS_V4 is
	enabled

Hi Trond,

On Mon, Sep 27, 2010 at 07:39:32AM -0400, Trond Myklebust wrote:
> On Mon, 2010-09-27 at 12:41 +0200, Uwe Kleine-König wrote:
> > NFS_V4 works fine without RPCSEC_GSS_KRB5 (even without CRYPTO).
> > This dependency was introduced in
> > 
> > 	df486a2 (NFS: Fix the selection of security flavours in Kconfig)
> > 
> > to fix a build failure as RPCSEC_GSS_KRB5 was thought to be needed for
> > NFS_V4.  The fix didn't work completely as NFS_V4 didn't enforce CRYPTO
> > and so the select on RPCSEC_GSS_KRB5 didn't work in all situations (e.g.
> > arm/mx1_defconfig).
> > 
> > This was rectified by
> > 
> > 	827e345 (SUNRPC: Fix the NFSv4 and RPCSEC_GSS Kconfig dependencies)
> > 
> > but the magic for RPCSEC_GSS_KRB5 introduced by df486a2 wasn't reverted.
> > 
> > Cc: Trond Myklebust <Trond.Myklebust@...app.com>
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> > ---
> > Hello,
> > 
> > after Trond sent me the patch that later ended in 827e345702 I suggested
> > to fold the patch below into it[1], but without reaction and success as I
> > noticed just now. :-(
> > 
> > Best regards
> > Uwe
> 
> That's because you completely fail to justify why should we change the
> behaviour to suddenly make RPCSEC_GSS_KRB5 optional for NFSv4. That has
> never been the case before.
My intention is not to make "RPCSEC_GSS_KRB5 optional for NFSv4".  First
I saw a build failure and then I wondered if the fix was optimal.  After
reading the log of 827e345 I thought NFSv4 doesn't depend on
RPCSEC_GSS_KRB5, still more considering that 827e345 was your fix after
I suggested to select CRYPTO to enforce RPCSEC_GSS_KRB5 again.

Currently you can have NFSv4 without RPCSEC_GSS_KRB5 because if you
don't have CRYPTO RPCSEC_GSS_KRB5 is off, too, even if it defaults to
yes and there's no prompt.  (Selecting would not work, too.)
And note that RPCSEC_GSS_KRB5 already selects SUNRPC_GSS, so 827e345
doesn't do anything useful if NFS_V4 really needs RPCSEC_GSS_KRB5.

So either we should really enforce RPCSEC_GSS_KRB5 if NFS_V4 is selected
(by letting one of these select CRYPTO, see e.g. my first patch, or by
letting NFS_V4 depend on CRYPTO) or make it optional in all cases (as it
is already now in some cases).

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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