sockets: remove unused KPIs to manipulate sockets

These KPIs were added in dd0e6c383a9f0 and through 15 years had zero use.
They slightly remind what IfAPI does for struct ifnet. But IfAPI does
that for the sake of large collection of NIC drivers not being aware of
struct ifnet. For the sockets it is unclear what could be a large
collection of externally written kernel modules that need extensively use
sockets and not be aware of their internals at the same time. This
isolation of a structure knowledge requires a lot of work, and just
throwing in a few KPIs isn't helpful.

Reviewed by: kib, olce, markj
Differential Revision: https://reviews.freebsd.org/D44311

tcp_fill_info(): Change lock assertion on INPCB to locked only

This function actually only ever reads from the TCP PCB. Consequently,
also make the pointer to its TCP PCB parameter const.

Sponsored by: NetApp, Inc. (originally)

sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

Path MTU discovery hooks for offloaded TCP connections.

Notify the TOE driver when when an ICMP type 3 code 4 (Fragmentation
needed and DF set) message is received for an offloaded connection.
This gives the driver an opportunity to lower the path MTU for the
connection and resume transmission, much like what the kernel does for
the connections that it handles.

Reviewed by: glebius@
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D29755

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.

Add a TOE KTLS mode and a TOE hook for allocating TLS sessions.

This adds the glue to allocate TLS sessions and invokes it from
the TLS enable socket option handler. This also adds some counters
for active TOE sessions.

The TOE KTLS mode is returned by getsockopt(TLSTX_TLS_MODE) when
TOE KTLS is in use on a socket, but cannot be set via setsockopt().

To simplify various checks, a TLS session now includes an explicit
'mode' member set to the value returned by TLSTX_TLS_MODE. Various
places that used to check 'sw_encrypt' against NULL to determine
software vs ifnet (NIC) TLS now check 'mode' instead.

Reviewed by: np, gallatin
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D21891

Add a hook to allow the toedev handling an offloaded connection to
provide accurate TCP_INFO.

Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D14816

sys: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

- Updated TOE support in the kernel.

- Stateful TCP offload drivers for Terminator 3 and 4 (T3 and T4) ASICs.
These are available as t3_tom and t4_tom modules that augment cxgb(4)
and cxgbe(4) respectively. The cxgb/cxgbe drivers continue to work as
usual with or without these extra features.

- iWARP driver for Terminator 3 ASIC (kernel verbs). T4 iWARP in the
works and will follow soon.

Build-tested with make universe.

30s overview
============
What interfaces support TCP offload? Look for TOE4 and/or TOE6 in the
capabilities of an interface:
# ifconfig -m | grep TOE

Enable/disable TCP offload on an interface (just like any other ifnet
capability):
# ifconfig cxgbe0 toe
# ifconfig cxgbe0 -toe

Which connections are offloaded? Look for toe4 and/or toe6 in the
output of netstat and sockstat:
# netstat -np tcp | grep toe
# sockstat -46c | grep toe

Reviewed by: bz, gnn
Sponsored by: Chelsio communications.
MFC after: ~3 months (after 9.1, and after ensuring MFC is feasible)

Fix typos - remove duplicate "the".

PR: bin/154928
Submitted by: Eitan Adler <lists at eitanadler.com>
MFC after: 3 days

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Replace struct tcpopt with a proxy toeopt struct in the TOE driver interface to
the TCP syncache. This returns struct tcpopt to being private within the TCP
implementation, thus allowing it to be modified without ABI concerns.

The patch breaks the ABI. Bump __FreeBSD_version to 800103 accordingly. The cxgb
driver is the only TOE consumer affected by this change, and needs to be
recompiled along with the kernel.

Suggested by: rwatson
Reviewed by: rwatson, kmacy
Approved by: re (kensmith), kensmith (mentor temporarily unavailable)

- Import the HEAD csup code which is the basis for the cvsmode work.

- Switch to INP_WLOCK macro from inp_wlock
- calling sodisconnect after tcp_twstart is both gratuitous and unsafe - remove

Submitted by: rwatson

Add versions of tcp_twstart, tcp_close, and tcp_drop that hide the acquisition the tcbinfo lock.

MFC after: 1 week

move cxgb_lt2.[ch] from NIC to TOE
move most offload functionality from NIC to TOE
factor out all socket and inpcb direct access
factor out access to locking in incpb, pcbinfo, and sockbuf

Incorporate TCP offload hooks in to core TCP code.
- Rename output routines tcp_gen_* -> tcp_output_*.
- Rename notification routines that turn in to no-ops in the absence of TOE
from tcp_gen_* -> tcp_offload_*.
- Fix some minor comment nits.
- Add a /* FALLTHROUGH */

Reviewed by: Sam Leffler, Robert Watson, and Mike Silbersack

incorporate feedback since initial commit
- rename tcp_ofld.[ch] to tcp_offload.[ch]
- document usage and locking conventions of the functions in the
toe_usrreqs function vector
- document tcpcb, inpcb, and socket fields used by toe
- widen the listen interface into 2 functions
- rename DISABLE_TCP_OFFLOAD to TCP_OFFLOAD_DISABLE
- shrink conditional compilation to reduce the likelihood of bitrot
- replace sc->sc_toepcb checks in tcp_syncache.c with TOEPCB_ISSET