Add kernel-side support for in-kernel TLS.

KTLS adds support for in-kernel framing and encryption of Transport
Layer Security (1.0-1.2) data on TCP sockets.  KTLS only supports
offload of TLS for transmitted data.  Key negotation must still be
performed in userland.  Once completed, transmit session keys for a
connection are provided to the kernel via a new TCP_TXTLS_ENABLE
socket option.  All subsequent data transmitted on the socket is
placed into TLS frames and encrypted using the supplied keys.

Any data written to a KTLS-enabled socket via write(2), aio_write(2),
or sendfile(2) is assumed to be application data and is encoded in TLS
frames with an application data type.  Individual records can be sent
with a custom type (e.g. handshake messages) via sendmsg(2) with a new
control message (TLS_SET_RECORD_TYPE) specifying the record type.

At present, rekeying is not supported though the in-kernel framework
should support rekeying.

KTLS makes use of the recently added unmapped mbufs to store TLS
frames in the socket buffer.  Each TLS frame is described by a single
ext_pgs mbuf.  The ext_pgs structure contains the header of the TLS
record (and trailer for encrypted records) as well as references to
the associated TLS session.

KTLS supports two primary methods of encrypting TLS frames: software
TLS and ifnet TLS.

Software TLS marks mbufs holding socket data as not ready via
M_NOTREADY similar to sendfile(2) when TLS framing information is
added to an unmapped mbuf in ktls_frame().  ktls_enqueue() is then
called to schedule TLS frames for encryption.  In the case of
sendfile_iodone() calls ktls_enqueue() instead of pru_ready() leaving
the mbufs marked M_NOTREADY until encryption is completed.  For other
writes (vn_sendfile when pages are available, write(2), etc.), the
PRUS_NOTREADY is set when invoking pru_send() along with invoking
ktls_enqueue().

A pool of worker threads (the "KTLS" kernel process) encrypts TLS
frames queued via ktls_enqueue().  Each TLS frame is temporarily
mapped using the direct map and passed to a software encryption
backend to perform the actual encryption.

(Note: The use of PHYS_TO_DMAP could be replaced with sf_bufs if
someone wished to make this work on architectures without a direct
map.)

KTLS supports pluggable software encryption backends.  Internally,
Netflix uses proprietary pure-software backends.  This commit includes
a simple backend in a new ktls_ocf.ko module that uses the kernel's
OpenCrypto framework to provide AES-GCM encryption of TLS frames.  As
a result, software TLS is now a bit of a misnomer as it can make use
of hardware crypto accelerators.

Once software encryption has finished, the TLS frame mbufs are marked
ready via pru_ready().  At this point, the encrypted data appears as
regular payload to the TCP stack stored in unmapped mbufs.

ifnet TLS permits a NIC to offload the TLS encryption and TCP
segmentation.  In this mode, a new send tag type (IF_SND_TAG_TYPE_TLS)
is allocated on the interface a socket is routed over and associated
with a TLS session.  TLS records for a TLS session using ifnet TLS are
not marked M_NOTREADY but are passed down the stack unencrypted.  The
ip_output_send() and ip6_output_send() helper functions that apply
send tags to outbound IP packets verify that the send tag of the TLS
record matches the outbound interface.  If so, the packet is tagged
with the TLS send tag and sent to the interface.  The NIC device
driver must recognize packets with the TLS send tag and schedule them
for TLS encryption and TCP segmentation.  If the the outbound
interface does not match the interface in the TLS send tag, the packet
is dropped.  In addition, a task is scheduled to refresh the TLS send
tag for the TLS session.  If a new TLS send tag cannot be allocated,
the connection is dropped.  If a new TLS send tag is allocated,
however, subsequent packets will be tagged with the correct TLS send
tag.  (This latter case has been tested by configuring both ports of a
Chelsio T6 in a lagg and failing over from one port to another.  As
the connections migrated to the new port, new TLS send tags were
allocated for the new port and connections resumed without being
dropped.)

ifnet TLS can be enabled and disabled on supported network interfaces
via new '[-]txtls[46]' options to ifconfig(8).  ifnet TLS is supported
across both vlan devices and lagg interfaces using failover, lacp with
flowid enabled, or lacp with flowid enabled.

Applications may request the current KTLS mode of a connection via a
new TCP_TXTLS_MODE socket option.  They can also use this socket
option to toggle between software and ifnet TLS modes.

In addition, a testing tool is available in tools/tools/switch_tls.
This is modeled on tcpdrop and uses similar syntax.  However, instead
of dropping connections, -s is used to force KTLS connections to
switch to software TLS and -i is used to switch to ifnet TLS.

Various sysctls and counters are available under the kern.ipc.tls
sysctl node.  The kern.ipc.tls.enable node must be set to true to
enable KTLS (it is off by default).  The use of unmapped mbufs must
also be enabled via kern.ipc.mb_use_ext_pgs to enable KTLS.

KTLS is enabled via the KERN_TLS kernel option.

This patch is the culmination of years of work by several folks
including Scott Long and Randall Stewart for the original design and
implementation; Drew Gallatin for several optimizations including the
use of ext_pgs mbufs, the M_NOTREADY mechanism for TLS records
awaiting software encryption, and pluggable software crypto backends;
and John Baldwin for modifications to support hardware TLS offload.

Reviewed by:	gallatin, hselasky, rrs
Obtained from:	Netflix
Sponsored by:	Netflix, Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D21277

newlib/libc/sys/rtems/include/net/if.h

@@ -247,6 +247,8 @@ struct if_data {
 #define	IFCAP_TXRTLMT		0x1000000 /* hardware supports TX rate limiting */
 #define	IFCAP_HWRXTSTMP		0x2000000 /* hardware rx timestamping */
 #define	IFCAP_NOMAP		0x4000000 /* can TX unmapped mbufs */
+#define	IFCAP_TXTLS4		0x8000000 /* can do TLS encryption and segmentation for TCP */
+#define	IFCAP_TXTLS6		0x10000000 /* can do TLS encryption and segmentation for TCP6 */
 
 #define IFCAP_HWCSUM_IPV6	(IFCAP_RXCSUM_IPV6 | IFCAP_TXCSUM_IPV6)
 
@@ -254,6 +256,7 @@ struct if_data {
 #define	IFCAP_TSO	(IFCAP_TSO4 | IFCAP_TSO6)
 #define	IFCAP_WOL	(IFCAP_WOL_UCAST | IFCAP_WOL_MCAST | IFCAP_WOL_MAGIC)
 #define	IFCAP_TOE	(IFCAP_TOE4 | IFCAP_TOE6)
+#define	IFCAP_TXTLS	(IFCAP_TXTLS4 | IFCAP_TXTLS6)
 
 #define	IFCAP_CANTCHANGE	(IFCAP_NETMAP)
 

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

@@ -29,7 +29,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)tcp.h	8.1 (Berkeley) 6/10/93
- * $FreeBSD: head/sys/netinet/tcp.h 334804 2018-06-07 18:18:13Z rrs $
+ * $FreeBSD: head/sys/netinet/tcp.h 351522 2019-08-27 00:01:56Z jhb $
  */
 
 #ifndef _NETINET_TCP_H_
@@ -174,6 +174,8 @@ struct tcphdr {
 #define	TCP_LOGDUMP	37	/* dump connection log events to device */
 #define	TCP_LOGDUMPID	38	/* dump events from connections with same ID to
 				   device */
+#define	TCP_TXTLS_ENABLE 39	/* TLS framing and encryption for transmit */
+#define	TCP_TXTLS_MODE	40	/* Transmit 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 */
@@ -350,4 +352,14 @@ struct tcp_function_set {
 	uint32_t pcbcnt;
 };
 
+/* TLS modes for TCP_TXTLS_MODE */
+#define	TCP_TLS_MODE_NONE	0
+#define	TCP_TLS_MODE_SW		1
+#define	TCP_TLS_MODE_IFNET	2
+
+/*
+ * TCP Control message types
+ */
+#define	TLS_SET_RECORD_TYPE	1
+
 #endif /* !_NETINET_TCP_H_ */