Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <3387b2e7-0921-cd80-279b-24d13f706443@linux.ibm.com>
Date:   Mon, 7 Feb 2022 20:50:48 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.5.1
Subject: Re: [PATCH v7 0/5] Allow guest access to EFI confidential computing
 secret area
Content-Language: en-US
To:     Matthew Garrett <mjg59@srcf.ucam.org>,
        Gerd Hoffmann <kraxel@redhat.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        James Bottomley <jejb@linux.ibm.com>,
        linux-efi <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>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Andi Kleen <ak@linux.intel.com>,
        Andrew Scull <ascull@google.com>,
        Dave Hansen <dave.hansen@intel.com>,
        "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
        Lenny Szubowicz <lszubowi@redhat.com>,
        Peter Gonda <pgonda@google.com>,
        Tobin Feldman-Fitzthum <tobin@linux.ibm.com>,
        Jim Cadden <jcadden@ibm.com>,
        Daniele Buono <dbuono@linux.vnet.ibm.com>,
        linux-coco@lists.linux.dev, linux-security-module@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Nayna Jain <nayna@linux.ibm.com>, dougmill@linux.vnet.ibm.com,
        gcwilson@linux.ibm.com, gjoyce@ibm.com,
        "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" 
        <linuxppc-dev@lists.ozlabs.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Daniel Axtens <dja@axtens.net>,
        Dov Murik <dovmurik@linux.ibm.com>
References: <Yfk6vEuZFtgtA+G+@kroah.com>
 <37779659ca96ac9c1f11bcc0ac0665895c795b54.camel@linux.ibm.com>
 <20220202040157.GA8019@srcf.ucam.org> <YfogOurPZb7+Yelo@kroah.com>
 <20220202065443.GA9249@srcf.ucam.org> <YfotMyQiQ66xfCOQ@kroah.com>
 <20220202071023.GA9489@srcf.ucam.org>
 <CAMj1kXFTyc9KnMsnvs+mt80DbJL8VGKKcQ0J=4NrGYGSAG8sRw@mail.gmail.com>
 <20220202080401.GA9861@srcf.ucam.org>
 <20220202083653.p3cb4w3qdud4e33t@sirius.home.kraxel.org>
 <20220202084534.GA10247@srcf.ucam.org>
From:   Dov Murik <dovmurik@linux.ibm.com>
In-Reply-To: <20220202084534.GA10247@srcf.ucam.org>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 02/02/2022 10:45, Matthew Garrett wrote:
> On Wed, Feb 02, 2022 at 09:36:53AM +0100, Gerd Hoffmann wrote:
> 
>> Having a "secrets/" directory looks good to me.  Then the individual
>> implementations can either add files to the directory, i.e. efi_secrets
>> would create "secrets/<guid>" files.  Or each implementation creates a
>> subdirectory with the secrets, i.e. "secrets/coco/" and
>> "secrets/coco/<guid>".
> 
> I prefer a subdirectory, on the basis that we could conceivably end up 
> with more than one implementation on a single device at some point, and 
> also because it makes it trivial for userland to determine what the 
> source is which may make a semantic difference under certain 
> circumstances.
>  

OK, sounds good.  In the next round of the series the module will create
the files in <securityfs>/secrets/coco/ .


>> Longer-term (i.e once we have more than one implementation) we probably
>> need a separate module which owns and manages the "secrets/" directory,
>> and possibly provides some common helper functions too.
> 
> Agree.

Yes; one candidate for such helper function is a filesystem that
implements the "wipe file content from memory on unlink".


-Dov