netipsec: fix LINT-NOINET build

udp_ipsec_input() is used for INET6, so we need it even in NOINET
builds. Build the relevant file if either of INET or INET6 are set.

Add UDP encapsulation of ESP in IPv6

This patch provides UDP encapsulation of ESP packets over IPv6.
Ports the IPv4 code to IPv6 and adds support for IPv6 in udpencap.c
As required by the RFC and unlike in IPv4 encapsulation,
UDP checksums are calculated.

Co-authored-by: Aurelien Cazuc <aurelien.cazuc.external@stormshield.eu>
Sponsored-by: Stormshield
Sponsored-by: Wiktel
Sponsored-by: Klara, Inc.

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

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

Fix kernel build after fcb3f813f379f544f9cd2a10d18045588da0e132 .

By updating function arguments for ipsec_kmod_ctlinput() which is used
when loading IPSEC support via kernel modules.

Differential Revision: https://reviews.freebsd.org/D36731
Sponsored by: NVIDIA Networking

netinet*: remove PRC_ constants and streamline ICMP processing

In the original design of the network stack from the protocol control
input method pr_ctlinput was used notify the protocols about two very
different kinds of events: internal system events and receival of an
ICMP messages from outside. These events were coded with PRC_ codes.
Today these methods are removed from the protosw(9) and are isolated
to IPv4 and IPv6 stacks and are called only from icmp*_input(). The
PRC_ codes now just create a shim layer between ICMP codes and errors
or actions taken by protocols.

- Change ipproto_ctlinput_t to pass just pointer to ICMP header. This
allows protocols to not deduct it from the internal IP header.
- Change ip6proto_ctlinput_t to pass just struct ip6ctlparam pointer.
It has all the information needed to the protocols. In the structure,
change ip6c_finaldst fields to sockaddr_in6. The reason is that
icmp6_input() already has this address wrapped in sockaddr, and the
protocols want this address as sockaddr.
- For UDP tunneling control input, as well as for IPSEC control input,
change the prototypes to accept a transparent union of either ICMP
header pointer or struct ip6ctlparam pointer.
- In icmp_input() and icmp6_input() do only validation of ICMP header and
count bad packets. The translation of ICMP codes to errors/actions is
done by protocols.
- Provide icmp_errmap() and icmp6_errmap() as substitute to inetctlerrmap,
inet6ctlerrmap arrays.
- In protocol ctlinput methods either trust what icmp_errmap() recommend,
or do our own logic based on the ICMP header.

Differential revision: https://reviews.freebsd.org/D36731

netipsec: move specific ipsecmethods declarations to ipsec_support.h

where struct ipsec_methods is defined. Not a functional change.
Allows further modification of method prototypes without breaking
compilation of other ipsec compilation units.

Differential revision: https://reviews.freebsd.org/D36730

ipsec: Handle ICMP NEEDFRAG message.

It will be needed for upcoming PMTU implementation in ipsec.
For now simply create/update an entry in tcp hostcache when needed.
The code is based on https://people.freebsd.org/~ae/ipsec_transport_mode_ctlinput.diff

Authored by: Kornel Duleba <mindal@semihalf.com>
Differential revision: https://reviews.freebsd.org/D30992
Reviewed by: tuxen
Sponsored by: Stormshield
Obtained from: Semihalf

Merge projects/ipsec into head/.

Small summary
-------------

o Almost all IPsec releated code was moved into sys/netipsec.
o New kernel modules added: ipsec.ko and tcpmd5.ko. New kernel
option IPSEC_SUPPORT added. It enables support for loading
and unloading of ipsec.ko and tcpmd5.ko kernel modules.
o IPSEC_NAT_T option was removed. Now NAT-T support is enabled by
default. The UDP_ENCAP_ESPINUDP_NON_IKE encapsulation type
support was removed. Added TCP/UDP checksum handling for
inbound packets that were decapsulated by transport mode SAs.
setkey(8) modified to show run-time NAT-T configuration of SA.
o New network pseudo interface if_ipsec(4) added. For now it is
build as part of ipsec.ko module (or with IPSEC kernel).
It implements IPsec virtual tunnels to create route-based VPNs.
o The network stack now invokes IPsec functions using special
methods. The only one header file <netipsec/ipsec_support.h>
should be included to declare all the needed things to work
with IPsec.
o All IPsec protocols handlers (ESP/AH/IPCOMP protosw) were removed.
Now these protocols are handled directly via IPsec methods.
o TCP_SIGNATURE support was reworked to be more close to RFC.
o PF_KEY SADB was reworked:
- now all security associations stored in the single SPI namespace,
and all SAs MUST have unique SPI.
- several hash tables added to speed up lookups in SADB.
- SADB now uses rmlock to protect access, and concurrent threads
can do SA lookups in the same time.
- many PF_KEY message handlers were reworked to reflect changes
in SADB.
- SADB_UPDATE message was extended to support new PF_KEY headers:
SADB_X_EXT_NEW_ADDRESS_SRC and SADB_X_EXT_NEW_ADDRESS_DST. They
can be used by IKE daemon to change SA addresses.
o ipsecrequest and secpolicy structures were cardinally changed to
avoid locking protection for ipsecrequest. Now we support
only limited number (4) of bundled SAs, but they are supported
for both INET and INET6.
o INPCB security policy cache was introduced. Each PCB now caches
used security policies to avoid SP lookup for each packet.
o For inbound security policies added the mode, when the kernel does
check for full history of applied IPsec transforms.
o References counting rules for security policies and security
associations were changed. The proper SA locking added into xform
code.
o xform code was also changed. Now it is possible to unregister xforms.
tdb_xxx structures were changed and renamed to reflect changes in
SADB/SPDB, and changed rules for locking and refcounting.

Reviewed by: gnn, wblock
Obtained from: Yandex LLC
Relnotes: yes
Sponsored by: Yandex LLC
Differential Revision: https://reviews.freebsd.org/D9352