[PATCH] crypto/virtio: fix DER encoding of RSA public key

[Gowrishankar Muthukrishnan]

As per RFC 8017, RSA public key in ASN.1 should have only
modulus and exponent values. Add a separate encoding function
to follow this standard.

Fixes: 6fe6a7f7bcf ("crypto/virtio: add asymmetric RSA support")

Signed-off-by: Gowrishankar Muthukrishnan <gmuthukri...@marvell.com>
---
 drivers/crypto/virtio/virtio_cryptodev.c | 31 +++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/virtio/virtio_cryptodev.c 
b/drivers/crypto/virtio/virtio_cryptodev.c
index bc737f1e68..b01e97c988 100644
--- a/drivers/crypto/virtio/virtio_cryptodev.c
+++ b/drivers/crypto/virtio/virtio_cryptodev.c
@@ -1524,6 +1524,29 @@ virtio_crypto_asym_rsa_xform_to_der(
        return len;
 }
 
+static int
+virtio_crypto_asym_rsa_xform_to_public_der(
+               struct rte_crypto_asym_xform *xform,
+               uint8_t *der)
+{
+       uint8_t data[VIRTIO_CRYPTO_MAX_CTRL_DATA];
+       size_t tlen = 0, len;
+       uint8_t *tlv;
+
+       if (xform->xform_type != RTE_CRYPTO_ASYM_XFORM_RSA)
+               return -EINVAL;
+
+       tlv = data;
+       len = tlv_encode(tlv, 0x02, xform->rsa.n.data, xform->rsa.n.length);
+       tlen += len;
+       len = tlv_encode(tlv + tlen, 0x02, xform->rsa.e.data, 
xform->rsa.e.length);
+       tlen += len;
+
+       RTE_ASSERT(tlen < VIRTIO_CRYPTO_MAX_CTRL_DATA);
+       len = tlv_encode(der, 0x30, data, tlen);
+       return len;
+}
+
 static int
 virtio_crypto_asym_rsa_configure_session(
                struct rte_crypto_rsa_xform *rsa,
@@ -1607,7 +1630,13 @@ virtio_crypto_asym_configure_session(
                        return ret;
                }
 
-               ret = virtio_crypto_asym_rsa_xform_to_der(xform, ctrl->data);
+               if (xform->rsa.key_type == RTE_RSA_KEY_TYPE_EXP) {
+                       ret = virtio_crypto_asym_rsa_xform_to_public_der(
+                                       xform, ctrl->data);
+               } else {
+                       ret = virtio_crypto_asym_rsa_xform_to_der(xform,
+                                       ctrl->data);
+               }
                if (ret <= 0) {
                        VIRTIO_CRYPTO_SESSION_LOG_ERR("Invalid RSA primitives");
                        return ret;
-- 
2.25.1