iscsi-target: Reject unsupported multi PDU text command sequence

This patch adds a check to reject text commands with F_BIT=0 ||
C_BIT=1, as multi PDU text command sequences are currently
unsupported.

This avoids the case where a text command received with F_BIT=0,
was generating a text response with F_BIT=1 which is a protocol
error according to RFC-3720 Section 10.11.1.
Reported-by: Arshad Hussain <arshad.hussain@calsoftinc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target.c

@@ -1948,6 +1948,13 @@ iscsit_setup_text_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 					 (unsigned char *)hdr);
 	}
 
+	if (!(hdr->flags & ISCSI_FLAG_CMD_FINAL) ||
+	     (hdr->flags & ISCSI_FLAG_TEXT_CONTINUE)) {
+		pr_err("Multi sequence text commands currently not supported\n");
+		return iscsit_reject_cmd(cmd, ISCSI_REASON_CMD_NOT_SUPPORTED,
+					(unsigned char *)hdr);
+	}
+
 	pr_debug("Got Text Request: ITT: 0x%08x, CmdSN: 0x%08x,"
 		" ExpStatSN: 0x%08x, Length: %u\n", hdr->itt, hdr->cmdsn,
 		hdr->exp_statsn, payload_length);