Initial support for kernel offload of TLS receive.

- Add a new TCP_RXTLS_ENABLE socket option to set the encryption and
  authentication algorithms and keys as well as the initial sequence
  number.

- When reading from a socket using KTLS receive, applications must use
  recvmsg().  Each successful call to recvmsg() will return a single
  TLS record.  A new TCP control message, TLS_GET_RECORD, will contain
  the TLS record header of the decrypted record.  The regular message
  buffer passed to recvmsg() will receive the decrypted payload.  This
  is similar to the interface used by Linux's KTLS RX except that
  Linux does not return the full TLS header in the control message.

- Add plumbing to the TOE KTLS interface to request either transmit
  or receive KTLS sessions.

- When a socket is using receive KTLS, redirect reads from
  soreceive_stream() into soreceive_generic().

- Note that this interface is currently only defined for TLS 1.1 and
  1.2, though I believe we will be able to reuse the same interface
  and structures for 1.3.

newlib/libc/sys/rtems/include/netinet/tcp.h

@@ -178,6 +178,8 @@ struct tcphdr {
 				   device */
 #define	TCP_TXTLS_ENABLE 39	/* TLS framing and encryption for transmit */
 #define	TCP_TXTLS_MODE	40	/* Transmit TLS mode */
+#define	TCP_RXTLS_ENABLE 41	/* TLS framing and encryption for receive */
+#define	TCP_RXTLS_MODE	42	/* Receive TLS mode */
 #define	TCP_CONGESTION	64	/* get/set congestion control algorithm */
 #define	TCP_CCALGOOPT	65	/* get/set cc algorithm specific options */
 #define TCP_DELACK  	72	/* socket option for delayed ack */
@@ -388,6 +390,7 @@ struct tcp_function_set {
  * TCP Control message types
  */
 #define	TLS_SET_RECORD_TYPE	1
+#define	TLS_GET_RECORD		2
 
 /*
  * TCP specific variables of interest for tp->t_stats stats(9) accounting.