iser-target: Ignore non TEXT + LOGOUT opcodes for discovery

This patch adds a check in isert_rx_opcode() to ignore non TEXT + LOGOUT
opcodes when SessionType=Discovery has been negotiated.

Cc: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/infiniband/ulp/isert/ib_isert.c

@@ -1066,11 +1066,19 @@ isert_rx_opcode(struct isert_conn *isert_conn, struct iser_rx_desc *rx_desc,
 {
 	struct iscsi_hdr *hdr = &rx_desc->iscsi_header;
 	struct iscsi_conn *conn = isert_conn->conn;
+	struct iscsi_session *sess = conn->sess;
 	struct iscsi_cmd *cmd;
 	struct isert_cmd *isert_cmd;
 	int ret = -EINVAL;
 	u8 opcode = (hdr->opcode & ISCSI_OPCODE_MASK);
 
+	if (sess->sess_ops->SessionType &&
+	   (!(opcode & ISCSI_OP_TEXT) || !(opcode & ISCSI_OP_LOGOUT))) {
+		pr_err("Got illegal opcode: 0x%02x in SessionType=Discovery,"
+		       " ignoring\n", opcode);
+		return 0;
+	}
+
 	switch (opcode) {
 	case ISCSI_OP_SCSI_CMD:
 		cmd = iscsit_allocate_cmd(conn, GFP_KERNEL);