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References: <20190727055214.9282-1-sean.j.christopherson@intel.com> <20190727055214.9282-22-sean.j.christopherson@intel.com>
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From:   Andy Lutomirski <luto@amacapital.net>
Date:   Sat, 27 Jul 2019 10:32:11 -0700
Message-ID: <CALCETrVJ1vMAA-7qtiZ8tg-3qyckSwbzNC2kbbHsojm+W46PWg@mail.gmail.com>
Subject: Re: [RFC PATCH 21/21] KVM: x86: Add capability to grant VM access to
 privileged SGX attribute
To:     Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        X86 ML <x86@kernel.org>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        "H. Peter Anvin" <hpa@zytor.com>, kvm list <kvm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, linux-sgx@vger.kernel.org
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On Fri, Jul 26, 2019 at 10:52 PM Sean Christopherson
<sean.j.christopherson@intel.com> wrote:
>
> The SGX subsystem restricts access to a subset of enclave attributes to
> provide additional security for an uncompromised kernel, e.g. to prevent
> malware from using the PROVISIONKEY to ensure its nodes are running
> inside a geniune SGX enclave and/or to obtain a stable fingerprint.
>
> To prevent userspace from circumventing such restrictions by running an
> enclave in a VM, KVM restricts guest access to privileged attributes by
> default.  Add a capability, KVM_CAP_SGX_ATTRIBUTE, that can be used by
> userspace to grant a VM access to a priveleged attribute, with args[0]
> holding a file handle to a valid SGX attribute file corresponding to
> an attribute that is restricted by KVM (currently only PROVISIONKEY).

Looks good to me.  Thanks!

> +can use KVM_CAP_SGX_ATTRIBUTE to grant a VM access to a priveleged attribute.

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