linux-kernel - Re: [RFC PATCH 03/13] kvm: Add XO memslot type

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 4 Oct 2019 09:27:09 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Rick Edgecombe <rick.p.edgecombe@...el.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, x86@...nel.org, linux-mm@...ck.org,
        luto@...nel.org, peterz@...radead.org, dave.hansen@...el.com,
        sean.j.christopherson@...el.com, keescook@...omium.org
Cc:     kristen@...ux.intel.com, deneen.t.dock@...el.com,
        Yu Zhang <yu.c.zhang@...ux.intel.com>
Subject: Re: [RFC PATCH 03/13] kvm: Add XO memslot type

On 03/10/19 23:23, Rick Edgecombe wrote:
> Add XO memslot type to create execute-only guest physical memory based on
> the RO memslot. Like the RO memslot, disallow changing the memslot type
> to/from XO.
> 
> In the EPT case ACC_USER_MASK represents the readable bit, so add the
> ability for set_spte() to unset this.
> 
> This is based in part on a patch by Yu Zhang.
> 
> Signed-off-by: Yu Zhang <yu.c.zhang@...ux.intel.com>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>

Instead of this, why not check the exit qualification gpa and, if it has
the XO bit set, mask away both the XO bit and the R bit?  It can be done
unconditionally for all memslots.  This should require no change to
userspace.

Paolo