[Part2 PATCH v6.1 20/38] crypto: ccp: Implement SEV_PDH_CERT_EXPORT ioctl command

[Brijesh Singh]

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@xxxxxxxxxx>
Cc: "Radim KrÄmÃÅ" <rkrcmar@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Gary Hook <gary.hook@xxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: linux-crypto@xxxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---

Changes since v6:
 * when sev_do_cmd() and sev_platform_shutdown() fails then propogate
   the error status code from sev_do_cmd() because it can give us
   much better reason for the failure.

 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 108fc06bcdb3..b9f594cb10c1 100644
--- a/drivers/crypto/ccp/psp-dev.c
+++ b/drivers/crypto/ccp/psp-dev.c
@@ -390,6 +390,113 @@ static int sev_ioctl_do_pek_cert_import(struct sev_issue_cmd *argp)
 	return ret;
 }
 
+static int sev_ioctl_do_pdh_cert_export(struct sev_issue_cmd *argp)
+{
+	struct sev_user_data_pdh_cert_export input;
+	void *pdh_blob = NULL, *cert_blob = NULL;
+	struct sev_data_pdh_cert_export *data;
+	int ret, err;
+
+	if (copy_from_user(&input, (void __user *)argp->data, sizeof(input)))
+		return -EFAULT;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	/* Userspace wants to query the certificate length */
+	if (!input.pdh_cert_address || !input.pdh_cert_len ||
+	    !input.cert_chain_address || !input.cert_chain_address)
+		goto cmd;
+
+	/* allocate a physically contiguous buffer to store the PDH blob */
+	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;
+
+	/* allocate a physically contiguous buffer to store the cert chain blob */
+	if (!access_ok(VERIFY_WRITE, input.cert_chain_address, input.cert_chain_len) ||
+	    (input.cert_chain_len > SEV_FW_BLOB_MAX_SIZE)) {
+		ret = -EFAULT;
+		goto e_free_pdh;
+	}
+
+	cert_blob = kmalloc(input.cert_chain_len, GFP_KERNEL);
+	if (!cert_blob) {
+		ret = -ENOMEM;
+		goto e_free_pdh;
+	}
+
+	data->cert_chain_address = __psp_pa(cert_blob);
+	data->cert_chain_len = input.cert_chain_len;
+
+cmd:
+	ret = sev_platform_init(NULL, &argp->error);
+	if (ret)
+		goto e_free_cert;
+
+	ret = sev_do_cmd(SEV_CMD_PDH_CERT_EXPORT, data, &argp->error);
+
+	/*
+	 * If we query the length, FW responded with expected data
+	 */
+	input.cert_chain_len = data->cert_chain_len;
+	input.pdh_cert_len = data->pdh_cert_len;
+
+	if (sev_platform_shutdown(&err)) {
+		/*
+		 * If both sev_do_cmd() and sev_platform_shutdown() commands
+		 * failed then propogate the error code from the sev_do_cmd()
+		 * because it contains a useful status code for the command
+		 * failure.
+		 */
+		if (ret)
+			goto e_free_cert;
+
+		ret = -EIO;
+		argp->error = err;
+		goto e_free_cert;
+	}
+
+	if (copy_to_user((void __user *)argp->data, &input, sizeof(input))) {
+		ret = -EFAULT;
+		goto e_free_cert;
+	}
+
+	if (pdh_blob) {
+		if (copy_to_user((void __user *)input.pdh_cert_address,
+				 pdh_blob, input.pdh_cert_len)) {
+			ret = -EFAULT;
+			goto e_free_cert;
+		}
+	}
+
+	if (cert_blob) {
+		if (copy_to_user((void __user *)input.cert_chain_address,
+				 cert_blob, input.cert_chain_len))
+			ret = -EFAULT;
+	}
+
+e_free_cert:
+	kfree(cert_blob);
+e_free_pdh:
+	kfree(pdh_blob);
+e_free:
+	kfree(data);
+	return ret;
+}
+
 static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
 {
 	void __user *argp = (void __user *)arg;
@@ -425,6 +532,9 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
 	case SEV_PEK_CERT_IMPORT:
 		ret = sev_ioctl_do_pek_cert_import(&input);
 		break;
+	case SEV_PDH_CERT_EXPORT:
+		ret = sev_ioctl_do_pdh_cert_export(&input);
+		break;
 	default:
 		ret = -EINVAL;
 		goto out;
-- 
2.9.5