linux-kernel - Re: [PATCH 1/2] x86: sgx_vepc: extract sgx_vepc_remove

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]

Message-ID: <de03361aab108ff481f6472978265e754100c6fb.camel@kernel.org>
Date:   Tue, 14 Sep 2021 00:16:37 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     x86@...nel.org, linux-sgx@...r.kernel.org,
        dave.hansen@...ux.intel.com, yang.zhong@...el.com
Subject: Re: [PATCH 1/2] x86: sgx_vepc: extract sgx_vepc_remove_page

On Mon, 2021-09-13 at 12:25 -0700, Dave Hansen wrote:
> On 9/13/21 11:35 AM, Paolo Bonzini wrote:
> > > > Apart from reclaiming, /dev/sgx_vepc might disappear between the first
> > > > open() and subsequent ones.
> > > 
> > > Aside from it being rm'd, I don't think that's possible.
> > > 
> > 
> > Being rm'd would be a possibility in principle, and it would be ugly for
> > it to cause issues on running VMs.  Also I'd like for it to be able to
> > pass /dev/sgx_vepc in via a file descriptor, and run QEMU in a chroot or
> > a mount namespace.  Alternatively, with seccomp it may be possible to
> > sandbox a running QEMU process in such a way that open() is forbidden at
> > runtime (all hotplug is done via file descriptor passing); it is not yet
> > possible, but it is a goal.
> 
> OK, so maybe another way of saying this:
> 
> For bare-metal SGX on real hardware, the hardware provides guarantees
> SGX state at reboot.  For instance, all pages start out uninitialized.
> The vepc driver provides a similar guarantee today for freshly-opened
> vepc instances.
> 
> But, vepc users have a problem: they might want to run an OS that
> expects to be booted with clean, fully uninitialized SGX state, just as
> it would be on bare-metal.  Right now, the only way to get that is to
> create a new vepc instance.  That might not be possible in all
> configurations, like if the permission to open(/dev/sgx_vepc) has been
> lost since the VM was first booted.

So you maintain your systems in a way that this does not happen?

/Jarkko