linux-kernel - Re: [Part2 PATCH v5.1 12.9/31] crypto: ccp: Implement SEV_PDH_CERT

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Date:   Fri, 13 Oct 2017 17:01:39 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Gary Hook <gary.hook@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        linux-crypto@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Part2 PATCH v5.1 12.9/31] crypto: ccp: Implement
 SEV_PDH_CERT_EXPORT ioctl command

On Fri, Oct 06, 2017 at 08:06:07PM -0500, Brijesh Singh wrote:
> The SEV_PDH_CERT_EXPORT command can be used to export the PDH and its
> certificate chain. The command is defined in SEV spec section 5.10.
> 
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: "Radim Krčmář" <rkrcmar@...hat.com>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Herbert Xu <herbert@...dor.apana.org.au>
> Cc: Gary Hook <gary.hook@....com>
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: linux-crypto@...r.kernel.org
> Cc: kvm@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  drivers/crypto/ccp/psp-dev.c | 110 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 110 insertions(+)
> 
> diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
> index 861c44bf2910..0a069e3c7b8c 100644
> --- a/drivers/crypto/ccp/psp-dev.c
> +++ b/drivers/crypto/ccp/psp-dev.c
> @@ -473,6 +473,112 @@ static int sev_ioctl_pek_cert_import(struct sev_issue_cmd *argp)
>  	return ret;
>  }
>  
> +static int sev_ioctl_pdh_cert_export(struct sev_issue_cmd *argp)
> +{
> +	struct sev_user_data_pdh_cert_export input;
> +	struct sev_data_pdh_cert_export *data;
> +	int ret, state, need_shutdown = 0;
> +	void *pdh_blob, *cert_blob;
> +
> +	if (copy_from_user(&input, (void __user *)(uintptr_t)argp->data,
> +			   sizeof(struct sev_user_data_pdh_cert_export)))
> +		return -EFAULT;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	pdh_blob = NULL;
> +	if (input.pdh_cert_address) {

Here...

> +		if (!access_ok(VERIFY_WRITE, input.pdh_cert_address, input.pdh_cert_len) ||
> +		     (input.pdh_cert_len > SEV_FW_BLOB_MAX_SIZE)) {
> +			ret = -EFAULT;
> +			goto e_free;
> +		}
> +
> +		pdh_blob = kmalloc(input.pdh_cert_len, GFP_KERNEL);
> +		if (!pdh_blob) {
> +			ret = -ENOMEM;
> +			goto e_free;
> +		}
> +
> +		data->pdh_cert_address = __psp_pa(pdh_blob);
> +		data->pdh_cert_len = input.pdh_cert_len;
> +	}
> +
> +	cert_blob = NULL;
> +	if (input.cert_chain_address) {

... and here please check the full condition where userspace queries the
cert length, like before.

Otherwise, the usual cleanups:

---
diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
index 5e69add4fea9..331d028f9445 100644
--- a/drivers/crypto/ccp/psp-dev.c
+++ b/drivers/crypto/ccp/psp-dev.c
@@ -476,8 +476,7 @@ static int sev_ioctl_pdh_cert_export(struct sev_issue_cmd *argp)
 	int ret, state, need_shutdown = 0;
 	void *pdh_blob, *cert_blob;
 
-	if (copy_from_user(&input, (void __user *)(uintptr_t)argp->data,
-			   sizeof(struct sev_user_data_pdh_cert_export)))
+	if (copy_from_user(&input, (void __user *)argp->data, sizeof(input)))
 		return -EFAULT;
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
@@ -536,36 +535,37 @@ static int sev_ioctl_pdh_cert_export(struct sev_issue_cmd *argp)
 		need_shutdown = 1;
 	}
 
-	ret = sev_handle_cmd(SEV_CMD_PDH_CERT_EXPORT, data, &argp->error);
+	ret = sev_do_cmd(SEV_CMD_PDH_CERT_EXPORT, data, &argp->error);
 
 	input.cert_chain_len = data->cert_chain_len;
 	input.pdh_cert_len = data->pdh_cert_len;
 
 	/* copy certificate length to userspace */
-	if (copy_to_user((void __user *)(uintptr_t)argp->data, &input,
-			 sizeof(struct sev_user_data_pdh_cert_export)))
+	if (copy_to_user((void __user *)argp->data, &input, sizeof(input)))
 		ret = -EFAULT;
 
 	if (ret)
 		goto e_shutdown;
 
 	/* copy PDH certificate to userspace */
-	if (pdh_blob &&
-	    copy_to_user((void __user *)(uintptr_t)input.pdh_cert_address,
-			 pdh_blob, input.pdh_cert_len)) {
-		ret = -EFAULT;
-		goto e_shutdown;
+	if (pdh_blob) {
+		if (copy_to_user((void __user *)input.pdh_cert_address,
+				 pdh_blob, input.pdh_cert_len)) {
+			ret = -EFAULT;
+			goto e_shutdown;
+		}
 	}
 
 	/* copy certificate chain to userspace */
-	if (cert_blob &&
-	    copy_to_user((void __user *)(uintptr_t)input.cert_chain_address,
-			 cert_blob, input.cert_chain_len))
-		ret = -EFAULT;
+	if (cert_blob) {
+		if (copy_to_user((void __user *)input.cert_chain_address,
+				  cert_blob, input.cert_chain_len))
+			ret = -EFAULT;
+	}
 
 e_shutdown:
 	if (need_shutdown)
-		sev_handle_cmd(SEV_CMD_SHUTDOWN, 0, NULL);
+		sev_do_cmd(SEV_CMD_SHUTDOWN, 0, NULL);
 e_free_cert:
 	kfree(cert_blob);
 e_free_pdh:
@@ -616,10 +616,9 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
 		ret = sev_ioctl_pek_cert_import(&input);
 		break;
 
-	case SEV_PDH_CERT_EXPORT: {
+	case SEV_PDH_CERT_EXPORT:
 		ret = sev_ioctl_pdh_cert_export(&input);
 		break;
-	}
 
 	default:
 		ret = -EINVAL;

-- 
Regards/Gruss,
    Boris.

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