linux-kernel - Re: [RFC Part2 PATCH v3 17/26] KVM: SVM: Add support for SEV LAUNCH

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Date:   Thu, 14 Sep 2017 12:20:43 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Joerg Roedel <joro@...tes.org>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        \"Radim Krčmář\" <rkrcmar@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [RFC Part2 PATCH v3 17/26] KVM: SVM: Add support for SEV
 LAUNCH_MEASURE command

On Mon, Jul 24, 2017 at 03:02:54PM -0500, Brijesh Singh wrote:
> The command is used to retrieve the measurement of memory encrypted
> through the LAUNCH_UPDATE_DATA command. This measurement can be used
> for attestation purposes.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  arch/x86/kvm/svm.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 91b070f..9b672eb 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -5957,6 +5957,54 @@ static int sev_launch_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  	return ret;
>  }
>  
> +static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> +	struct sev_data_launch_measure *data = NULL;
> +	struct kvm_sev_launch_measure params;
> +	void *addr = NULL;
> +	int ret;
> +
> +	if (!sev_guest(kvm))
> +		return -ENOTTY;
> +
> +	if (copy_from_user(&params, (void *)argp->data,
> +				sizeof(struct kvm_sev_launch_measure)))
> +		return -EFAULT;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	if (params.address && params.length) {


Same notes as before: check userspace data and make data a stack var.

Thx.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--