nvmet-tcp: fix receive data digest calculation for multiple h2cdata PDUs

When a host sends multiple h2cdata PDUs for a single command, we
should verify the data digest calculation per PDU and not
per command.

Fixes: 872d26a3 ("nvmet-tcp: add NVMe over TCP target driver")
Reported-by: Narayan Ayalasomayajula <Narayan.Ayalasomayajula@wdc.com>
Tested-by: Narayan Ayalasomayajula <Narayan.Ayalasomayajula@wdc.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/tcp.c

@@ -378,7 +378,7 @@ static int nvmet_tcp_map_data(struct nvmet_tcp_cmd *cmd)
 	return NVME_SC_INTERNAL;
 }
 
-static void nvmet_tcp_ddgst(struct ahash_request *hash,
+static void nvmet_tcp_send_ddgst(struct ahash_request *hash,
 		struct nvmet_tcp_cmd *cmd)
 {
 	ahash_request_set_crypt(hash, cmd->req.sg,
@@ -386,6 +386,23 @@ static void nvmet_tcp_ddgst(struct ahash_request *hash,
 	crypto_ahash_digest(hash);
 }
 
+static void nvmet_tcp_recv_ddgst(struct ahash_request *hash,
+		struct nvmet_tcp_cmd *cmd)
+{
+	struct scatterlist sg;
+	struct kvec *iov;
+	int i;
+
+	crypto_ahash_init(hash);
+	for (i = 0, iov = cmd->iov; i < cmd->nr_mapped; i++, iov++) {
+		sg_init_one(&sg, iov->iov_base, iov->iov_len);
+		ahash_request_set_crypt(hash, &sg, NULL, iov->iov_len);
+		crypto_ahash_update(hash);
+	}
+	ahash_request_set_crypt(hash, NULL, (void *)&cmd->exp_ddgst, 0);
+	crypto_ahash_final(hash);
+}
+
 static void nvmet_setup_c2h_data_pdu(struct nvmet_tcp_cmd *cmd)
 {
 	struct nvme_tcp_data_pdu *pdu = cmd->data_pdu;
@@ -410,7 +427,7 @@ static void nvmet_setup_c2h_data_pdu(struct nvmet_tcp_cmd *cmd)
 
 	if (queue->data_digest) {
 		pdu->hdr.flags |= NVME_TCP_F_DDGST;
-		nvmet_tcp_ddgst(queue->snd_hash, cmd);
+		nvmet_tcp_send_ddgst(queue->snd_hash, cmd);
 	}
 
 	if (cmd->queue->hdr_digest) {
@@ -1059,7 +1076,7 @@ static void nvmet_tcp_prep_recv_ddgst(struct nvmet_tcp_cmd *cmd)
 {
 	struct nvmet_tcp_queue *queue = cmd->queue;
 
-	nvmet_tcp_ddgst(queue->rcv_hash, cmd);
+	nvmet_tcp_recv_ddgst(queue->rcv_hash, cmd);
 	queue->offset = 0;
 	queue->left = NVME_TCP_DIGEST_LENGTH;
 	queue->rcv_state = NVMET_TCP_RECV_DDGST;
@@ -1080,14 +1097,14 @@ static int nvmet_tcp_try_recv_data(struct nvmet_tcp_queue *queue)
 		cmd->rbytes_done += ret;
 	}
 
+	if (queue->data_digest) {
+		nvmet_tcp_prep_recv_ddgst(cmd);
+		return 0;
+	}
 	nvmet_tcp_unmap_pdu_iovec(cmd);
 
 	if (!(cmd->flags & NVMET_TCP_F_INIT_FAILED) &&
 	    cmd->rbytes_done == cmd->req.transfer_len) {
-		if (queue->data_digest) {
-			nvmet_tcp_prep_recv_ddgst(cmd);
-			return 0;
-		}
 		cmd->req.execute(&cmd->req);
 	}