[dpdk-dev] [PATCH v2 1/8] crypto/aesni_gcm: do not append digest

[Pablo de Lara <pablo.de.lara.guarch@intel.com>]

When performing an authentication verification,
the PMD was using memory at the end of the input buffer,
to store temporarily the digest.
This operation requires the buffer to have enough
tailroom unnecessarily.
Instead, memory is allocated for each queue pair, to store
temporarily the digest generated by the driver, so it can
be compared with the one provided in the crypto operation,
without needing to touch the input buffer.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
---
 drivers/crypto/aesni_gcm/aesni_gcm_pmd.c         | 31 +++++-------------------
 drivers/crypto/aesni_gcm/aesni_gcm_pmd_private.h |  7 ++++++
 2 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/drivers/crypto/aesni_gcm/aesni_gcm_pmd.c b/drivers/crypto/aesni_gcm/aesni_gcm_pmd.c
index d9c91d0..8c9c211 100644
--- a/drivers/crypto/aesni_gcm/aesni_gcm_pmd.c
+++ b/drivers/crypto/aesni_gcm/aesni_gcm_pmd.c
@@ -298,14 +298,7 @@ process_gcm_crypto_op(struct aesni_gcm_qp *qp, struct rte_crypto_op *op,
 				sym_op->aead.digest.data,
 				(uint64_t)session->digest_length);
 	} else if (session->op == AESNI_GCM_OP_AUTHENTICATED_DECRYPTION) {
-		uint8_t *auth_tag = (uint8_t *)rte_pktmbuf_append(sym_op->m_dst ?
-				sym_op->m_dst : sym_op->m_src,
-				session->digest_length);
-
-		if (!auth_tag) {
-			GCM_LOG_ERR("auth_tag");
-			return -1;
-		}
+		uint8_t *auth_tag = qp->temp_digest;
 
 		qp->ops[session->key].init(&session->gdata_key,
 				&qp->gdata_ctx,
@@ -350,14 +343,7 @@ process_gcm_crypto_op(struct aesni_gcm_qp *qp, struct rte_crypto_op *op,
 				sym_op->auth.digest.data,
 				(uint64_t)session->digest_length);
 	} else { /* AESNI_GMAC_OP_VERIFY */
-		uint8_t *auth_tag = (uint8_t *)rte_pktmbuf_append(sym_op->m_dst ?
-				sym_op->m_dst : sym_op->m_src,
-				session->digest_length);
-
-		if (!auth_tag) {
-			GCM_LOG_ERR("auth_tag");
-			return -1;
-		}
+		uint8_t *auth_tag = qp->temp_digest;
 
 		qp->ops[session->key].init(&session->gdata_key,
 				&qp->gdata_ctx,
@@ -385,11 +371,10 @@ process_gcm_crypto_op(struct aesni_gcm_qp *qp, struct rte_crypto_op *op,
  * - Returns NULL on invalid job
  */
 static void
-post_process_gcm_crypto_op(struct rte_crypto_op *op,
+post_process_gcm_crypto_op(struct aesni_gcm_qp *qp,
+		struct rte_crypto_op *op,
 		struct aesni_gcm_session *session)
 {
-	struct rte_mbuf *m = op->sym->m_dst ? op->sym->m_dst : op->sym->m_src;
-
 	op->status = RTE_CRYPTO_OP_STATUS_SUCCESS;
 
 	/* Verify digest if required */
@@ -397,8 +382,7 @@ post_process_gcm_crypto_op(struct rte_crypto_op *op,
 			session->op == AESNI_GMAC_OP_VERIFY) {
 		uint8_t *digest;
 
-		uint8_t *tag = rte_pktmbuf_mtod_offset(m, uint8_t *,
-				m->data_len - session->digest_length);
+		uint8_t *tag = (uint8_t *)&qp->temp_digest;
 
 		if (session->op == AESNI_GMAC_OP_VERIFY)
 			digest = op->sym->auth.digest.data;
@@ -414,9 +398,6 @@ post_process_gcm_crypto_op(struct rte_crypto_op *op,
 
 		if (memcmp(tag, digest,	session->digest_length) != 0)
 			op->status = RTE_CRYPTO_OP_STATUS_AUTH_FAILED;
-
-		/* trim area used for digest from mbuf */
-		rte_pktmbuf_trim(m, session->digest_length);
 	}
 }
 
@@ -435,7 +416,7 @@ handle_completed_gcm_crypto_op(struct aesni_gcm_qp *qp,
 		struct rte_crypto_op *op,
 		struct aesni_gcm_session *sess)
 {
-	post_process_gcm_crypto_op(op, sess);
+	post_process_gcm_crypto_op(qp, op, sess);
 
 	/* Free session if a session-less crypto op */
 	if (op->sess_type == RTE_CRYPTO_OP_SESSIONLESS) {
diff --git a/drivers/crypto/aesni_gcm/aesni_gcm_pmd_private.h b/drivers/crypto/aesni_gcm/aesni_gcm_pmd_private.h
index 7e15572..1c8835b 100644
--- a/drivers/crypto/aesni_gcm/aesni_gcm_pmd_private.h
+++ b/drivers/crypto/aesni_gcm/aesni_gcm_pmd_private.h
@@ -58,6 +58,8 @@
 #define GCM_LOG_DBG(fmt, args...)
 #endif
 
+/* Maximum length for digest */
+#define DIGEST_LENGTH_MAX 16
 
 /** private data structure for each virtual AESNI GCM device */
 struct aesni_gcm_private {
@@ -84,6 +86,11 @@ struct aesni_gcm_qp {
 	/**< Queue Pair Identifier */
 	char name[RTE_CRYPTODEV_NAME_LEN];
 	/**< Unique Queue Pair Name */
+	uint8_t temp_digest[DIGEST_LENGTH_MAX];
+	/**< Buffer used to store the digest generated
+	 * by the driver when verifying a digest provided
+	 * by the user (using authentication verify operation)
+	 */
 } __rte_cache_aligned;
 
 
-- 
2.9.4