[6/6] vhost/crypto: fix possible TOCTOU attack
diff mbox series

Message ID 20200928105918.740807-6-ferruh.yigit@intel.com
State Accepted
Delegated to: Thomas Monjalon
Headers show
Series
  • [1/6] vhost/crypto: fix pool allocation
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Commit Message

Ferruh Yigit Sept. 28, 2020, 10:59 a.m. UTC
From: Fan Zhang <roy.fan.zhang@intel.com>

This patch fixes the possible time-of-check to time-of-use (TOCTOU)
attack problem by copying request data and descriptor index to local
variable prior to process.

Also the original sequential read of descriptors may lead to TOCTOU
attack. This patch fixes the problem by loading all descriptors of a
request to local buffer before processing.

CVE-2020-14375
Fixes: 3bb595ecd682 ("vhost/crypto: add request handler")
Cc: stable@dpdk.org

Signed-off-by: Fan Zhang <roy.fan.zhang@intel.com>
Acked-by: Chenbo Xia <chenbo.xia@intel.com>
---
 lib/librte_vhost/rte_vhost_crypto.h |   2 +
 lib/librte_vhost/vhost_crypto.c     | 391 ++++++++++++++--------------
 2 files changed, 202 insertions(+), 191 deletions(-)

Comments

Thomas Monjalon Sept. 28, 2020, 3:19 p.m. UTC | #1
> From: Fan Zhang <roy.fan.zhang@intel.com>
> 
> This patch fixes the possible time-of-check to time-of-use (TOCTOU)
> attack problem by copying request data and descriptor index to local
> variable prior to process.
> 
> Also the original sequential read of descriptors may lead to TOCTOU
> attack. This patch fixes the problem by loading all descriptors of a
> request to local buffer before processing.
> 
> CVE-2020-14375
> Fixes: 3bb595ecd682 ("vhost/crypto: add request handler")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Fan Zhang <roy.fan.zhang@intel.com>
> Acked-by: Chenbo Xia <chenbo.xia@intel.com>

Series applied in the main repository, thanks.

Patch
diff mbox series

diff --git a/lib/librte_vhost/rte_vhost_crypto.h b/lib/librte_vhost/rte_vhost_crypto.h
index 866a592a5d..b54d61db69 100644
--- a/lib/librte_vhost/rte_vhost_crypto.h
+++ b/lib/librte_vhost/rte_vhost_crypto.h
@@ -7,10 +7,12 @@ 
 
 #define VHOST_CRYPTO_MBUF_POOL_SIZE		(8192)
 #define VHOST_CRYPTO_MAX_BURST_SIZE		(64)
+#define VHOST_CRYPTO_MAX_DATA_SIZE		(4096)
 #define VHOST_CRYPTO_SESSION_MAP_ENTRIES	(1024) /**< Max nb sessions */
 /** max nb virtual queues in a burst for finalizing*/
 #define VIRTIO_CRYPTO_MAX_NUM_BURST_VQS		(64)
 #define VHOST_CRYPTO_MAX_IV_LEN			(32)
+#define VHOST_CRYPTO_MAX_N_DESC			(32)
 
 enum rte_vhost_crypto_zero_copy {
 	RTE_VHOST_CRYPTO_ZERO_COPY_DISABLE = 0,
diff --git a/lib/librte_vhost/vhost_crypto.c b/lib/librte_vhost/vhost_crypto.c
index cf9aa2566b..e08f9c6d75 100644
--- a/lib/librte_vhost/vhost_crypto.c
+++ b/lib/librte_vhost/vhost_crypto.c
@@ -46,6 +46,14 @@ 
 #define IOVA_TO_VVA(t, r, a, l, p)					\
 	((t)(uintptr_t)vhost_iova_to_vva(r->dev, r->vq, a, l, p))
 
+/*
+ * vhost_crypto_desc is used to copy original vring_desc to the local buffer
+ * before processing (except the next index). The copy result will be an
+ * array of vhost_crypto_desc elements that follows the sequence of original
+ * vring_desc.next is arranged.
+ */
+#define vhost_crypto_desc vring_desc
+
 static int
 cipher_algo_transform(uint32_t virtio_cipher_algo,
 		enum rte_crypto_cipher_algorithm *algo)
@@ -479,83 +487,71 @@  vhost_crypto_msg_post_handler(int vid, void *msg)
 	return ret;
 }
 
-static __rte_always_inline struct vring_desc *
-find_write_desc(struct vring_desc *head, struct vring_desc *desc,
-		uint32_t *nb_descs, uint32_t vq_size)
+static __rte_always_inline struct vhost_crypto_desc *
+find_write_desc(struct vhost_crypto_desc *head, struct vhost_crypto_desc *desc,
+		uint32_t max_n_descs)
 {
-	if (desc->flags & VRING_DESC_F_WRITE)
-		return desc;
-
-	while (desc->flags & VRING_DESC_F_NEXT) {
-		if (unlikely(*nb_descs == 0 || desc->next >= vq_size))
-			return NULL;
-		(*nb_descs)--;
+	if (desc < head)
+		return NULL;
 
-		desc = &head[desc->next];
+	while (desc - head < (int)max_n_descs) {
 		if (desc->flags & VRING_DESC_F_WRITE)
 			return desc;
+		desc++;
 	}
 
 	return NULL;
 }
 
-static struct virtio_crypto_inhdr *
-reach_inhdr(struct vhost_crypto_data_req *vc_req, struct vring_desc *desc,
-		uint32_t *nb_descs, uint32_t vq_size)
+static __rte_always_inline struct virtio_crypto_inhdr *
+reach_inhdr(struct vhost_crypto_data_req *vc_req,
+		struct vhost_crypto_desc *head,
+		uint32_t max_n_descs)
 {
-	uint64_t dlen;
 	struct virtio_crypto_inhdr *inhdr;
+	struct vhost_crypto_desc *last = head + (max_n_descs - 1);
+	uint64_t dlen = last->len;
 
-	while (desc->flags & VRING_DESC_F_NEXT) {
-		if (unlikely(*nb_descs == 0 || desc->next >= vq_size))
-			return NULL;
-		(*nb_descs)--;
-		desc = &vc_req->head[desc->next];
-	}
+	if (unlikely(dlen != sizeof(*inhdr)))
+		return NULL;
 
-	dlen = desc->len;
-	inhdr = IOVA_TO_VVA(struct virtio_crypto_inhdr *, vc_req, desc->addr,
+	inhdr = IOVA_TO_VVA(struct virtio_crypto_inhdr *, vc_req, last->addr,
 			&dlen, VHOST_ACCESS_WO);
-	if (unlikely(!inhdr || dlen != desc->len))
+	if (unlikely(!inhdr || dlen != last->len))
 		return NULL;
 
 	return inhdr;
 }
 
 static __rte_always_inline int
-move_desc(struct vring_desc *head, struct vring_desc **cur_desc,
-		uint32_t size, uint32_t *nb_descs, uint32_t vq_size)
+move_desc(struct vhost_crypto_desc *head,
+		struct vhost_crypto_desc **cur_desc,
+		uint32_t size, uint32_t max_n_descs)
 {
-	struct vring_desc *desc = *cur_desc;
+	struct vhost_crypto_desc *desc = *cur_desc;
 	int left = size - desc->len;
 
-	while ((desc->flags & VRING_DESC_F_NEXT) && left > 0) {
-		if (unlikely(*nb_descs == 0 || desc->next >= vq_size))
-			return -1;
-
-		desc = &head[desc->next];
-		rte_prefetch0(&head[desc->next]);
+	while (desc->flags & VRING_DESC_F_NEXT && left > 0 &&
+			desc >= head &&
+			desc - head < (int)max_n_descs) {
+		desc++;
 		left -= desc->len;
-		if (left > 0)
-			(*nb_descs)--;
 	}
 
 	if (unlikely(left > 0))
 		return -1;
 
-	if (unlikely(*nb_descs == 0))
+	if (unlikely(head - desc == (int)max_n_descs))
 		*cur_desc = NULL;
-	else {
-		if (unlikely(desc->next >= vq_size))
-			return -1;
-		*cur_desc = &head[desc->next];
-	}
+	else
+		*cur_desc = desc + 1;
 
 	return 0;
 }
 
 static __rte_always_inline void *
-get_data_ptr(struct vhost_crypto_data_req *vc_req, struct vring_desc *cur_desc,
+get_data_ptr(struct vhost_crypto_data_req *vc_req,
+		struct vhost_crypto_desc *cur_desc,
 		uint8_t perm)
 {
 	void *data;
@@ -570,12 +566,13 @@  get_data_ptr(struct vhost_crypto_data_req *vc_req, struct vring_desc *cur_desc,
 	return data;
 }
 
-static int
+static __rte_always_inline int
 copy_data(void *dst_data, struct vhost_crypto_data_req *vc_req,
-		struct vring_desc **cur_desc, uint32_t size,
-		uint32_t *nb_descs, uint32_t vq_size)
+		struct vhost_crypto_desc *head,
+		struct vhost_crypto_desc **cur_desc,
+		uint32_t size, uint32_t max_n_descs)
 {
-	struct vring_desc *desc = *cur_desc;
+	struct vhost_crypto_desc *desc = *cur_desc;
 	uint64_t remain, addr, dlen, len;
 	uint32_t to_copy;
 	uint8_t *data = dst_data;
@@ -614,15 +611,8 @@  copy_data(void *dst_data, struct vhost_crypto_data_req *vc_req,
 
 	left -= to_copy;
 
-	while ((desc->flags & VRING_DESC_F_NEXT) && left > 0) {
-		if (unlikely(*nb_descs == 0 || desc->next >= vq_size)) {
-			VC_LOG_ERR("Invalid descriptors");
-			return -1;
-		}
-		(*nb_descs)--;
-
-		desc = &vc_req->head[desc->next];
-		rte_prefetch0(&vc_req->head[desc->next]);
+	while (desc >= head && desc - head < (int)max_n_descs && left) {
+		desc++;
 		to_copy = RTE_MIN(desc->len, (uint32_t)left);
 		dlen = to_copy;
 		src = IOVA_TO_VVA(uint8_t *, vc_req, desc->addr, &dlen,
@@ -663,13 +653,10 @@  copy_data(void *dst_data, struct vhost_crypto_data_req *vc_req,
 		return -1;
 	}
 
-	if (unlikely(*nb_descs == 0))
+	if (unlikely(desc - head == (int)max_n_descs))
 		*cur_desc = NULL;
-	else {
-		if (unlikely(desc->next >= vq_size))
-			return -1;
-		*cur_desc = &vc_req->head[desc->next];
-	}
+	else
+		*cur_desc = desc + 1;
 
 	return 0;
 }
@@ -681,6 +668,7 @@  write_back_data(struct vhost_crypto_data_req *vc_req)
 
 	while (wb_data) {
 		rte_memcpy(wb_data->dst, wb_data->src, wb_data->len);
+		memset(wb_data->src, 0, wb_data->len);
 		wb_last = wb_data;
 		wb_data = wb_data->next;
 		rte_mempool_put(vc_req->wb_pool, wb_last);
@@ -722,17 +710,18 @@  free_wb_data(struct vhost_crypto_writeback_data *wb_data,
  * @return
  *   The pointer to the start of the write back data linked list.
  */
-static struct vhost_crypto_writeback_data *
+static __rte_always_inline struct vhost_crypto_writeback_data *
 prepare_write_back_data(struct vhost_crypto_data_req *vc_req,
-		struct vring_desc **cur_desc,
+		struct vhost_crypto_desc *head_desc,
+		struct vhost_crypto_desc **cur_desc,
 		struct vhost_crypto_writeback_data **end_wb_data,
 		uint8_t *src,
 		uint32_t offset,
 		uint64_t write_back_len,
-		uint32_t *nb_descs, uint32_t vq_size)
+		uint32_t max_n_descs)
 {
 	struct vhost_crypto_writeback_data *wb_data, *head;
-	struct vring_desc *desc = *cur_desc;
+	struct vhost_crypto_desc *desc = *cur_desc;
 	uint64_t dlen;
 	uint8_t *dst;
 	int ret;
@@ -775,14 +764,10 @@  prepare_write_back_data(struct vhost_crypto_data_req *vc_req,
 	} else
 		offset -= desc->len;
 
-	while (write_back_len) {
-		if (unlikely(*nb_descs == 0 || desc->next >= vq_size)) {
-			VC_LOG_ERR("Invalid descriptors");
-			goto error_exit;
-		}
-		(*nb_descs)--;
-
-		desc = &vc_req->head[desc->next];
+	while (write_back_len &&
+			desc >= head_desc &&
+			desc - head_desc < (int)max_n_descs) {
+		desc++;
 		if (unlikely(!(desc->flags & VRING_DESC_F_WRITE))) {
 			VC_LOG_ERR("incorrect descriptor");
 			goto error_exit;
@@ -821,13 +806,10 @@  prepare_write_back_data(struct vhost_crypto_data_req *vc_req,
 			wb_data->next = NULL;
 	}
 
-	if (unlikely(*nb_descs == 0))
+	if (unlikely(desc - head_desc == (int)max_n_descs))
 		*cur_desc = NULL;
-	else {
-		if (unlikely(desc->next >= vq_size))
-			goto error_exit;
-		*cur_desc = &vc_req->head[desc->next];
-	}
+	else
+		*cur_desc = desc + 1;
 
 	*end_wb_data = wb_data;
 
@@ -851,14 +833,14 @@  vhost_crypto_check_cipher_request(struct virtio_crypto_cipher_data_req *req)
 	return VIRTIO_CRYPTO_BADMSG;
 }
 
-static uint8_t
+static __rte_always_inline uint8_t
 prepare_sym_cipher_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 		struct vhost_crypto_data_req *vc_req,
 		struct virtio_crypto_cipher_data_req *cipher,
-		struct vring_desc *cur_desc,
-		uint32_t *nb_descs, uint32_t vq_size)
+		struct vhost_crypto_desc *head,
+		uint32_t max_n_descs)
 {
-	struct vring_desc *desc = cur_desc;
+	struct vhost_crypto_desc *desc = head;
 	struct vhost_crypto_writeback_data *ewb = NULL;
 	struct rte_mbuf *m_src = op->sym->m_src, *m_dst = op->sym->m_dst;
 	uint8_t *iv_data = rte_crypto_op_ctod_offset(op, uint8_t *, IV_OFFSET);
@@ -869,8 +851,8 @@  prepare_sym_cipher_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 
 	/* prepare */
 	/* iv */
-	if (unlikely(copy_data(iv_data, vc_req, &desc, cipher->para.iv_len,
-			nb_descs, vq_size) < 0)) {
+	if (unlikely(copy_data(iv_data, vc_req, head, &desc,
+			cipher->para.iv_len, max_n_descs))) {
 		ret = VIRTIO_CRYPTO_BADMSG;
 		goto error_exit;
 	}
@@ -888,9 +870,8 @@  prepare_sym_cipher_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 			goto error_exit;
 		}
 
-		if (unlikely(move_desc(vc_req->head, &desc,
-				cipher->para.src_data_len, nb_descs,
-				vq_size) < 0)) {
+		if (unlikely(move_desc(head, &desc, cipher->para.src_data_len,
+				max_n_descs) < 0)) {
 			VC_LOG_ERR("Incorrect descriptor");
 			ret = VIRTIO_CRYPTO_ERR;
 			goto error_exit;
@@ -901,8 +882,8 @@  prepare_sym_cipher_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 		vc_req->wb_pool = vcrypto->wb_pool;
 		m_src->data_len = cipher->para.src_data_len;
 		if (unlikely(copy_data(rte_pktmbuf_mtod(m_src, uint8_t *),
-				vc_req, &desc, cipher->para.src_data_len,
-				nb_descs, vq_size) < 0)) {
+				vc_req, head, &desc, cipher->para.src_data_len,
+				max_n_descs) < 0)) {
 			ret = VIRTIO_CRYPTO_BADMSG;
 			goto error_exit;
 		}
@@ -913,7 +894,7 @@  prepare_sym_cipher_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 	}
 
 	/* dst */
-	desc = find_write_desc(vc_req->head, desc, nb_descs, vq_size);
+	desc = find_write_desc(head, desc, max_n_descs);
 	if (unlikely(!desc)) {
 		VC_LOG_ERR("Cannot find write location");
 		ret = VIRTIO_CRYPTO_BADMSG;
@@ -931,9 +912,8 @@  prepare_sym_cipher_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 			goto error_exit;
 		}
 
-		if (unlikely(move_desc(vc_req->head, &desc,
-				cipher->para.dst_data_len,
-				nb_descs, vq_size) < 0)) {
+		if (unlikely(move_desc(head, &desc, cipher->para.dst_data_len,
+				max_n_descs) < 0)) {
 			VC_LOG_ERR("Incorrect descriptor");
 			ret = VIRTIO_CRYPTO_ERR;
 			goto error_exit;
@@ -942,9 +922,9 @@  prepare_sym_cipher_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 		m_dst->data_len = cipher->para.dst_data_len;
 		break;
 	case RTE_VHOST_CRYPTO_ZERO_COPY_DISABLE:
-		vc_req->wb = prepare_write_back_data(vc_req, &desc, &ewb,
+		vc_req->wb = prepare_write_back_data(vc_req, head, &desc, &ewb,
 				rte_pktmbuf_mtod(m_src, uint8_t *), 0,
-				cipher->para.dst_data_len, nb_descs, vq_size);
+				cipher->para.dst_data_len, max_n_descs);
 		if (unlikely(vc_req->wb == NULL)) {
 			ret = VIRTIO_CRYPTO_ERR;
 			goto error_exit;
@@ -986,33 +966,33 @@  static __rte_always_inline uint8_t
 vhost_crypto_check_chain_request(struct virtio_crypto_alg_chain_data_req *req)
 {
 	if (likely((req->para.iv_len <= VHOST_CRYPTO_MAX_IV_LEN) &&
-		(req->para.src_data_len <= RTE_MBUF_DEFAULT_DATAROOM) &&
+		(req->para.src_data_len <= VHOST_CRYPTO_MAX_DATA_SIZE) &&
 		(req->para.dst_data_len >= req->para.src_data_len) &&
-		(req->para.dst_data_len <= RTE_MBUF_DEFAULT_DATAROOM) &&
+		(req->para.dst_data_len <= VHOST_CRYPTO_MAX_DATA_SIZE) &&
 		(req->para.cipher_start_src_offset <
-			RTE_MBUF_DEFAULT_DATAROOM) &&
-		(req->para.len_to_cipher < RTE_MBUF_DEFAULT_DATAROOM) &&
+			VHOST_CRYPTO_MAX_DATA_SIZE) &&
+		(req->para.len_to_cipher <= VHOST_CRYPTO_MAX_DATA_SIZE) &&
 		(req->para.hash_start_src_offset <
-			RTE_MBUF_DEFAULT_DATAROOM) &&
-		(req->para.len_to_hash < RTE_MBUF_DEFAULT_DATAROOM) &&
+			VHOST_CRYPTO_MAX_DATA_SIZE) &&
+		(req->para.len_to_hash <= VHOST_CRYPTO_MAX_DATA_SIZE) &&
 		(req->para.cipher_start_src_offset + req->para.len_to_cipher <=
 			req->para.src_data_len) &&
 		(req->para.hash_start_src_offset + req->para.len_to_hash <=
 			req->para.src_data_len) &&
 		(req->para.dst_data_len + req->para.hash_result_len <=
-			RTE_MBUF_DEFAULT_DATAROOM)))
+			VHOST_CRYPTO_MAX_DATA_SIZE)))
 		return VIRTIO_CRYPTO_OK;
 	return VIRTIO_CRYPTO_BADMSG;
 }
 
-static uint8_t
+static __rte_always_inline uint8_t
 prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 		struct vhost_crypto_data_req *vc_req,
 		struct virtio_crypto_alg_chain_data_req *chain,
-		struct vring_desc *cur_desc,
-		uint32_t *nb_descs, uint32_t vq_size)
+		struct vhost_crypto_desc *head,
+		uint32_t max_n_descs)
 {
-	struct vring_desc *desc = cur_desc, *digest_desc;
+	struct vhost_crypto_desc *desc = head, *digest_desc;
 	struct vhost_crypto_writeback_data *ewb = NULL, *ewb2 = NULL;
 	struct rte_mbuf *m_src = op->sym->m_src, *m_dst = op->sym->m_dst;
 	uint8_t *iv_data = rte_crypto_op_ctod_offset(op, uint8_t *, IV_OFFSET);
@@ -1025,8 +1005,8 @@  prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 
 	/* prepare */
 	/* iv */
-	if (unlikely(copy_data(iv_data, vc_req, &desc,
-			chain->para.iv_len, nb_descs, vq_size) < 0)) {
+	if (unlikely(copy_data(iv_data, vc_req, head, &desc,
+			chain->para.iv_len, max_n_descs) < 0)) {
 		ret = VIRTIO_CRYPTO_BADMSG;
 		goto error_exit;
 	}
@@ -1045,9 +1025,8 @@  prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 			goto error_exit;
 		}
 
-		if (unlikely(move_desc(vc_req->head, &desc,
-				chain->para.src_data_len,
-				nb_descs, vq_size) < 0)) {
+		if (unlikely(move_desc(head, &desc, chain->para.src_data_len,
+				max_n_descs) < 0)) {
 			VC_LOG_ERR("Incorrect descriptor");
 			ret = VIRTIO_CRYPTO_ERR;
 			goto error_exit;
@@ -1057,8 +1036,8 @@  prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 		vc_req->wb_pool = vcrypto->wb_pool;
 		m_src->data_len = chain->para.src_data_len;
 		if (unlikely(copy_data(rte_pktmbuf_mtod(m_src, uint8_t *),
-				vc_req, &desc, chain->para.src_data_len,
-				nb_descs, vq_size) < 0)) {
+				vc_req, head, &desc, chain->para.src_data_len,
+				max_n_descs) < 0)) {
 			ret = VIRTIO_CRYPTO_BADMSG;
 			goto error_exit;
 		}
@@ -1070,7 +1049,7 @@  prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 	}
 
 	/* dst */
-	desc = find_write_desc(vc_req->head, desc, nb_descs, vq_size);
+	desc = find_write_desc(head, desc, max_n_descs);
 	if (unlikely(!desc)) {
 		VC_LOG_ERR("Cannot find write location");
 		ret = VIRTIO_CRYPTO_BADMSG;
@@ -1089,8 +1068,7 @@  prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 		}
 
 		if (unlikely(move_desc(vc_req->head, &desc,
-				chain->para.dst_data_len,
-				nb_descs, vq_size) < 0)) {
+				chain->para.dst_data_len, max_n_descs) < 0)) {
 			VC_LOG_ERR("Incorrect descriptor");
 			ret = VIRTIO_CRYPTO_ERR;
 			goto error_exit;
@@ -1106,9 +1084,9 @@  prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 			goto error_exit;
 		}
 
-		if (unlikely(move_desc(vc_req->head, &desc,
+		if (unlikely(move_desc(head, &desc,
 				chain->para.hash_result_len,
-				nb_descs, vq_size) < 0)) {
+				max_n_descs) < 0)) {
 			VC_LOG_ERR("Incorrect descriptor");
 			ret = VIRTIO_CRYPTO_ERR;
 			goto error_exit;
@@ -1116,34 +1094,34 @@  prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 
 		break;
 	case RTE_VHOST_CRYPTO_ZERO_COPY_DISABLE:
-		vc_req->wb = prepare_write_back_data(vc_req, &desc, &ewb,
+		vc_req->wb = prepare_write_back_data(vc_req, head, &desc, &ewb,
 				rte_pktmbuf_mtod(m_src, uint8_t *),
 				chain->para.cipher_start_src_offset,
 				chain->para.dst_data_len -
-				chain->para.cipher_start_src_offset,
-				nb_descs, vq_size);
+					chain->para.cipher_start_src_offset,
+				max_n_descs);
 		if (unlikely(vc_req->wb == NULL)) {
 			ret = VIRTIO_CRYPTO_ERR;
 			goto error_exit;
 		}
 
+		digest_desc = desc;
 		digest_offset = m_src->data_len;
 		digest_addr = rte_pktmbuf_mtod_offset(m_src, void *,
 				digest_offset);
-		digest_desc = desc;
 
 		/** create a wb_data for digest */
-		ewb->next = prepare_write_back_data(vc_req, &desc, &ewb2,
-				digest_addr, 0, chain->para.hash_result_len,
-				nb_descs, vq_size);
+		ewb->next = prepare_write_back_data(vc_req, head, &desc,
+				&ewb2, digest_addr, 0,
+				chain->para.hash_result_len, max_n_descs);
 		if (unlikely(ewb->next == NULL)) {
 			ret = VIRTIO_CRYPTO_ERR;
 			goto error_exit;
 		}
 
-		if (unlikely(copy_data(digest_addr, vc_req, &digest_desc,
+		if (unlikely(copy_data(digest_addr, vc_req, head, &digest_desc,
 				chain->para.hash_result_len,
-				nb_descs, vq_size) < 0)) {
+				max_n_descs) < 0)) {
 			ret = VIRTIO_CRYPTO_BADMSG;
 			goto error_exit;
 		}
@@ -1193,74 +1171,103 @@  prepare_sym_chain_op(struct vhost_crypto *vcrypto, struct rte_crypto_op *op,
 static __rte_always_inline int
 vhost_crypto_process_one_req(struct vhost_crypto *vcrypto,
 		struct vhost_virtqueue *vq, struct rte_crypto_op *op,
-		struct vring_desc *head, uint16_t desc_idx)
+		struct vring_desc *head, struct vhost_crypto_desc *descs,
+		uint16_t desc_idx)
 {
 	struct vhost_crypto_data_req *vc_req = rte_mbuf_to_priv(op->sym->m_src);
 	struct rte_cryptodev_sym_session *session;
-	struct virtio_crypto_op_data_req *req, tmp_req;
+	struct virtio_crypto_op_data_req req;
 	struct virtio_crypto_inhdr *inhdr;
-	struct vring_desc *desc = NULL;
+	struct vhost_crypto_desc *desc = descs;
+	struct vring_desc *src_desc;
 	uint64_t session_id;
 	uint64_t dlen;
-	uint32_t nb_descs = vq->size;
-	int err = 0;
+	uint32_t nb_descs = 0, max_n_descs, i;
+	int err;
 
 	vc_req->desc_idx = desc_idx;
 	vc_req->dev = vcrypto->dev;
 	vc_req->vq = vq;
 
-	if (likely(head->flags & VRING_DESC_F_INDIRECT)) {
-		dlen = head->len;
-		nb_descs = dlen / sizeof(struct vring_desc);
-		/* drop invalid descriptors */
-		if (unlikely(nb_descs > vq->size))
-			return -1;
-		desc = IOVA_TO_VVA(struct vring_desc *, vc_req, head->addr,
-				&dlen, VHOST_ACCESS_RO);
-		if (unlikely(!desc || dlen != head->len))
-			return -1;
-		desc_idx = 0;
-		head = desc;
-	} else {
-		desc = head;
+	if (unlikely((head->flags & VRING_DESC_F_INDIRECT) == 0)) {
+		VC_LOG_ERR("Invalid descriptor");
+		return -1;
 	}
 
-	vc_req->head = head;
-	vc_req->zero_copy = vcrypto->option;
+	dlen = head->len;
+	src_desc = IOVA_TO_VVA(struct vring_desc *, vc_req, head->addr,
+			&dlen, VHOST_ACCESS_RO);
+	if (unlikely(!src_desc || dlen != head->len)) {
+		VC_LOG_ERR("Invalid descriptor");
+		return -1;
+	}
+	head = src_desc;
 
-	req = get_data_ptr(vc_req, desc, VHOST_ACCESS_RO);
-	if (unlikely(req == NULL)) {
-		switch (vcrypto->option) {
-		case RTE_VHOST_CRYPTO_ZERO_COPY_ENABLE:
-			err = VIRTIO_CRYPTO_BADMSG;
-			VC_LOG_ERR("Invalid descriptor");
-			goto error_exit;
-		case RTE_VHOST_CRYPTO_ZERO_COPY_DISABLE:
-			req = &tmp_req;
-			if (unlikely(copy_data(req, vc_req, &desc, sizeof(*req),
-					&nb_descs, vq->size) < 0)) {
-				err = VIRTIO_CRYPTO_BADMSG;
-				VC_LOG_ERR("Invalid descriptor");
-				goto error_exit;
+	nb_descs = max_n_descs = dlen / sizeof(struct vring_desc);
+	if (unlikely(nb_descs > VHOST_CRYPTO_MAX_N_DESC || nb_descs == 0)) {
+		err = VIRTIO_CRYPTO_ERR;
+		VC_LOG_ERR("Cannot process num of descriptors %u", nb_descs);
+		if (nb_descs > 0) {
+			struct vring_desc *inhdr_desc = head;
+			while (inhdr_desc->flags & VRING_DESC_F_NEXT) {
+				if (inhdr_desc->next >= max_n_descs)
+					return -1;
+				inhdr_desc = &head[inhdr_desc->next];
 			}
-			break;
-		default:
-			err = VIRTIO_CRYPTO_ERR;
-			VC_LOG_ERR("Invalid option");
-			goto error_exit;
+			if (inhdr_desc->len != sizeof(*inhdr))
+				return -1;
+			inhdr = IOVA_TO_VVA(struct virtio_crypto_inhdr *,
+					vc_req, inhdr_desc->addr, &dlen,
+					VHOST_ACCESS_WO);
+			if (unlikely(!inhdr || dlen != inhdr_desc->len))
+				return -1;
+			inhdr->status = VIRTIO_CRYPTO_ERR;
+			return -1;
 		}
-	} else {
-		if (unlikely(move_desc(vc_req->head, &desc,
-				sizeof(*req), &nb_descs, vq->size) < 0)) {
-			VC_LOG_ERR("Incorrect descriptor");
+	}
+
+	/* copy descriptors to local variable */
+	for (i = 0; i < max_n_descs; i++) {
+		desc->addr = src_desc->addr;
+		desc->len = src_desc->len;
+		desc->flags = src_desc->flags;
+		desc++;
+		if (unlikely((src_desc->flags & VRING_DESC_F_NEXT) == 0))
+			break;
+		if (unlikely(src_desc->next >= max_n_descs)) {
+			err = VIRTIO_CRYPTO_BADMSG;
+			VC_LOG_ERR("Invalid descriptor");
 			goto error_exit;
 		}
+		src_desc = &head[src_desc->next];
+	}
+
+	vc_req->head = head;
+	vc_req->zero_copy = vcrypto->option;
+
+	nb_descs = desc - descs;
+	desc = descs;
+
+	if (unlikely(desc->len < sizeof(req))) {
+		err = VIRTIO_CRYPTO_BADMSG;
+		VC_LOG_ERR("Invalid descriptor");
+		goto error_exit;
 	}
 
-	switch (req->header.opcode) {
+	if (unlikely(copy_data(&req, vc_req, descs, &desc, sizeof(req),
+			max_n_descs) < 0)) {
+		err = VIRTIO_CRYPTO_BADMSG;
+		VC_LOG_ERR("Invalid descriptor");
+		goto error_exit;
+	}
+
+	/* desc is advanced by 1 now */
+	max_n_descs -= 1;
+
+	switch (req.header.opcode) {
 	case VIRTIO_CRYPTO_CIPHER_ENCRYPT:
 	case VIRTIO_CRYPTO_CIPHER_DECRYPT:
-		session_id = req->header.session_id;
+		session_id = req.header.session_id;
 
 		/* one branch to avoid unnecessary table lookup */
 		if (vcrypto->cache_session_id != session_id) {
@@ -1286,19 +1293,19 @@  vhost_crypto_process_one_req(struct vhost_crypto *vcrypto,
 			goto error_exit;
 		}
 
-		switch (req->u.sym_req.op_type) {
+		switch (req.u.sym_req.op_type) {
 		case VIRTIO_CRYPTO_SYM_OP_NONE:
 			err = VIRTIO_CRYPTO_NOTSUPP;
 			break;
 		case VIRTIO_CRYPTO_SYM_OP_CIPHER:
 			err = prepare_sym_cipher_op(vcrypto, op, vc_req,
-					&req->u.sym_req.u.cipher, desc,
-					&nb_descs, vq->size);
+					&req.u.sym_req.u.cipher, desc,
+					max_n_descs);
 			break;
 		case VIRTIO_CRYPTO_SYM_OP_ALGORITHM_CHAINING:
 			err = prepare_sym_chain_op(vcrypto, op, vc_req,
-					&req->u.sym_req.u.chain, desc,
-					&nb_descs, vq->size);
+					&req.u.sym_req.u.chain, desc,
+					max_n_descs);
 			break;
 		}
 		if (unlikely(err != 0)) {
@@ -1307,8 +1314,9 @@  vhost_crypto_process_one_req(struct vhost_crypto *vcrypto,
 		}
 		break;
 	default:
+		err = VIRTIO_CRYPTO_ERR;
 		VC_LOG_ERR("Unsupported symmetric crypto request type %u",
-				req->header.opcode);
+				req.header.opcode);
 		goto error_exit;
 	}
 
@@ -1316,7 +1324,7 @@  vhost_crypto_process_one_req(struct vhost_crypto *vcrypto,
 
 error_exit:
 
-	inhdr = reach_inhdr(vc_req, desc, &nb_descs, vq->size);
+	inhdr = reach_inhdr(vc_req, descs, max_n_descs);
 	if (likely(inhdr != NULL))
 		inhdr->status = (uint8_t)err;
 
@@ -1330,17 +1338,16 @@  vhost_crypto_finalize_one_request(struct rte_crypto_op *op,
 	struct rte_mbuf *m_src = op->sym->m_src;
 	struct rte_mbuf *m_dst = op->sym->m_dst;
 	struct vhost_crypto_data_req *vc_req = rte_mbuf_to_priv(m_src);
-	uint16_t desc_idx;
+	struct vhost_virtqueue *vq = vc_req->vq;
+	uint16_t used_idx = vc_req->desc_idx, desc_idx;
 
 	if (unlikely(!vc_req)) {
 		VC_LOG_ERR("Failed to retrieve vc_req");
 		return NULL;
 	}
 
-	if (old_vq && (vc_req->vq != old_vq))
-		return vc_req->vq;
-
-	desc_idx = vc_req->desc_idx;
+	if (old_vq && (vq != old_vq))
+		return vq;
 
 	if (unlikely(op->status != RTE_CRYPTO_OP_STATUS_SUCCESS))
 		vc_req->inhdr->status = VIRTIO_CRYPTO_ERR;
@@ -1349,8 +1356,9 @@  vhost_crypto_finalize_one_request(struct rte_crypto_op *op,
 			write_back_data(vc_req);
 	}
 
-	vc_req->vq->used->ring[desc_idx].id = desc_idx;
-	vc_req->vq->used->ring[desc_idx].len = vc_req->len;
+	desc_idx = vq->avail->ring[used_idx];
+	vq->used->ring[desc_idx].id = vq->avail->ring[desc_idx];
+	vq->used->ring[desc_idx].len = vc_req->len;
 
 	rte_mempool_put(m_src->pool, (void *)m_src);
 
@@ -1448,7 +1456,7 @@  rte_vhost_crypto_create(int vid, uint8_t cryptodev_id,
 	vcrypto->mbuf_pool = rte_pktmbuf_pool_create(name,
 			VHOST_CRYPTO_MBUF_POOL_SIZE, 512,
 			sizeof(struct vhost_crypto_data_req),
-			RTE_MBUF_DEFAULT_DATAROOM * 2 + RTE_PKTMBUF_HEADROOM,
+			VHOST_CRYPTO_MAX_DATA_SIZE + RTE_PKTMBUF_HEADROOM,
 			rte_socket_id());
 	if (!vcrypto->mbuf_pool) {
 		VC_LOG_ERR("Failed to creath mbuf pool");
@@ -1574,6 +1582,7 @@  rte_vhost_crypto_fetch_requests(int vid, uint32_t qid,
 		struct rte_crypto_op **ops, uint16_t nb_ops)
 {
 	struct rte_mbuf *mbufs[VHOST_CRYPTO_MAX_BURST_SIZE * 2];
+	struct vhost_crypto_desc descs[VHOST_CRYPTO_MAX_N_DESC];
 	struct virtio_net *dev = get_device(vid);
 	struct vhost_crypto *vcrypto;
 	struct vhost_virtqueue *vq;
@@ -1632,7 +1641,7 @@  rte_vhost_crypto_fetch_requests(int vid, uint32_t qid,
 			op->sym->m_dst->data_off = 0;
 
 			if (unlikely(vhost_crypto_process_one_req(vcrypto, vq,
-					op, head, desc_idx) < 0))
+					op, head, descs, used_idx) < 0))
 				break;
 		}
 
@@ -1661,7 +1670,7 @@  rte_vhost_crypto_fetch_requests(int vid, uint32_t qid,
 			op->sym->m_src->data_off = 0;
 
 			if (unlikely(vhost_crypto_process_one_req(vcrypto, vq,
-					op, head, desc_idx) < 0))
+					op, head, descs, desc_idx) < 0))
 				break;
 		}