[PATCH v2] RDMA/rxe: Implement packet length validation on responder

[Daisuke Matsuda <matsuda-daisuke@fujitsu.com>]

The function check_length() is supposed to check the length of inbound
packets on responder, but it actually has been a stub since the driver was
born. Let it check the payload length and the DMA length.

Signed-off-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com>
---
FOR REVIEWERS
  I referred to IB Specification Vol 1-Revision-1.5 to create this patch.
  Please see 9.7.4.1.6 (page.330).

v2: Fixed the conditional for 'last' packets. Thanks, Zhijian.

 drivers/infiniband/sw/rxe/rxe_resp.c | 34 ++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
index c32bc12cc82f..382d2053db43 100644
--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -393,16 +393,36 @@ static enum resp_states check_resource(struct rxe_qp *qp,
 static enum resp_states check_length(struct rxe_qp *qp,
 				     struct rxe_pkt_info *pkt)
 {
-	switch (qp_type(qp)) {
-	case IB_QPT_RC:
-		return RESPST_CHK_RKEY;
+	int mtu = qp->mtu;
+	u32 payload = payload_size(pkt);
+	u32 dmalen = reth_len(pkt);
 
-	case IB_QPT_UC:
-		return RESPST_CHK_RKEY;
+	/* RoCEv2 packets do not have LRH.
+	 * Let's skip checking it.
+	 */
 
-	default:
-		return RESPST_CHK_RKEY;
+	if ((pkt->opcode & RXE_START_MASK) &&
+	    (pkt->opcode & RXE_END_MASK)) {
+		/* "only" packets */
+		if (payload > mtu)
+			return RESPST_ERR_LENGTH;
+	} else if ((pkt->opcode & RXE_START_MASK) ||
+		   (pkt->opcode & RXE_MIDDLE_MASK)) {
+		/* "first" or "middle" packets */
+		if (payload != mtu)
+			return RESPST_ERR_LENGTH;
+	} else if (pkt->opcode & RXE_END_MASK) {
+		/* "last" packets */
+		if ((payload == 0) || (payload > mtu))
+			return RESPST_ERR_LENGTH;
+	}
+
+	if (pkt->opcode & (RXE_WRITE_MASK | RXE_READ_MASK)) {
+		if (dmalen > (1 << 31))
+			return RESPST_ERR_LENGTH;
 	}
+
+	return RESPST_CHK_RKEY;
 }
 
 static enum resp_states check_rkey(struct rxe_qp *qp,
-- 
2.31.1