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From: Greg KH <gregkh@linuxfoundation.org>
To: James Bottomley <jejb@linux.ibm.com>
Cc: Dov Murik <dovmurik@linux.ibm.com>,
	linux-efi@vger.kernel.org, Borislav Petkov <bp@suse.de>,
	Ashish Kalra <ashish.kalra@amd.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Andi Kleen <ak@linux.intel.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Tobin Feldman-Fitzthum <tobin@linux.ibm.com>,
	Jim Cadden <jcadden@ibm.com>,
	linux-coco@lists.linux.dev,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] Allow access to confidential computing secret area in SEV guests
Date: Thu, 2 Sep 2021 18:09:55 +0200	[thread overview]
Message-ID: <YTD3U70FCkXzNMrF@kroah.com> (raw)
In-Reply-To: <6cb65cb3bd69ae69bde044f809525e478bdb8512.camel@linux.ibm.com>

On Thu, Sep 02, 2021 at 08:19:51AM -0700, James Bottomley wrote:
> On Thu, 2021-09-02 at 17:05 +0200, Greg KH wrote:
> > On Thu, Sep 02, 2021 at 07:35:10AM -0700, James Bottomley wrote:
> > > On Thu, 2021-09-02 at 14:57 +0200, Greg KH wrote:
> > > [...]
> > > > Wait, why are you using securityfs for this?
> > > > 
> > > > securityfs is for LSMs to use. 
> > > 
> > > No it isn't ... at least not exclusively; we use it for non LSM
> > > security purposes as well, like for the TPM BIOS log and for
> > > IMA.  What makes you think we should start restricting securityfs
> > > to LSMs only?  That's not been the policy up to now.
> > 
> > Well that was the original intent of the filesystem when it was
> > created, but I guess it's really up to the LSM maintainers now what
> > they want it for.
> > 
> > > >  If you want your own filesystem to play around with stuff like
> > > > this, great, write your own, it's only 200 lines or less these
> > > > days.  We used to do it all the time until people realized they
> > > > should just use sysfs for driver stuff.
> > > 
> > > This is a security purpose (injected key retrieval), so securityfs
> > > seems to be the best choice.  It's certainly possible to create a
> > > new filesystem, but I really think things with a security purpose
> > > should use securityfs so people know where to look for them.
> > 
> > knowing where to look should not be an issue, as that should be
> > documented in Documentation/ABI/ anyway, right?
> > 
> > It's just the overlap / overreach of using an existing filesystem for
> > things that don't seem to be LSM-related that feels odd to me.
> > 
> > Why not just make a cocofs if those people want a filesystem
> > interface?
> > It's 200 lines or so these days, if not less, and that way you only
> > mount what you actually need for the system.
> 
> Secrets transfer is actually broader than confidential computing,
> although confidential computing is a first proposed use, so I think
> cocofs would be too narrow.
> 
> > Why force this into securityfs if it doesn't have to be?
> 
> It's not being forced.  Secrets transfer is a security function in the
> same way the bios log is.

Is the bios log in securityfs today?

Anyway, it's up to the securityfs maintainer (i.e. not me), but
personally, I think this should be a separate filesystem as that would
probably make things easier in the long run...

good luck!

greg k-h

  reply	other threads:[~2021-09-02 16:25 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-09 19:01 Dov Murik
2021-08-09 19:01 ` [PATCH 1/3] efi/libstub: Copy confidential computing secret area Dov Murik
2021-08-09 19:01 ` [PATCH 2/3] efi: Reserve " Dov Murik
2021-08-09 19:01 ` [PATCH 3/3] virt: Add sev_secret module to expose confidential computing secrets Dov Murik
2021-08-13 13:05   ` Andrew Scull
2021-08-16  9:56     ` Ard Biesheuvel
2021-08-19 13:02       ` Andrew Scull
2021-08-20 18:36         ` Dov Murik
2021-08-23 19:21           ` Andrew Scull
2021-09-02 12:59   ` Greg KH
2021-09-02 18:14     ` Dov Murik
2021-09-02 12:57 ` [PATCH 0/3] Allow access to confidential computing secret area in SEV guests Greg KH
2021-09-02 14:35   ` James Bottomley
2021-09-02 15:05     ` Greg KH
2021-09-02 15:19       ` James Bottomley
2021-09-02 16:09         ` Greg KH [this message]
2021-09-02 16:19           ` James Bottomley
2021-09-02 16:31             ` Greg KH

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