Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Optimisation in IPSEC(4):
- Remove contention on ISR during the crypto operation by using rwlock(9).
- Remove a second lookup of the SA in the callback.

Gain on 6 cores CPU with SHA1/AES128 can be up to 30%.

Reviewed by: vanhu
MFC after: 1 month

Fixed IPsec's HMAC_SHA256-512 support to be RFC4868 compliant.
This will break interoperability with all older versions of
FreeBSD for those algorithms.

Reviewed by: bz, gnn
Obtained from: NETASQ
MFC after: 1w

Add sysctls to if_enc(4) to control whether the firewalls or
bpf will see inner and outer headers or just inner or outer
headers for incoming and outgoing IPsec packets.

This is useful in bpf to not have over long lines for debugging
or selcting packets based on the inner headers.
It also properly defines the behavior of what the firewalls see.

Last but not least it gives you if_enc(4) for IPv6 as well.

[ As some auxiliary state was not available in the later
input path we save it in the tdbi. That way tcpdump can give a
consistent view of either of (authentic,confidential) for both
before and after states. ]

Discussed with: thompsa (2007-04-25, basic idea of unifying paths)
Reviewed by: thompsa, gnn

Fix more stack corruptions on amd64.

Vararg functions have a different calling convention than regular
functions on amd64. Casting a varag function to a regular one to
match the function pointer declaration will hide the varargs from
the caller and we will end up with an incorrectly setup stack.

Entirely remove the varargs from these functions and change the
functions to match the declaration of the function pointers.
Remove the now unnecessary casts.

Also change static struct ipprotosw[] to two independent
protosw/ip6protosw definitions to remove an unnecessary cast.

PR: amd64/95008
Submitted and tested by: Mats Palmgren
Reviewed by: rwatson
MFC after: 3 days

/* -> /*- for license, minor formatting changes

"Fast IPsec": this is an experimental IPsec implementation that is derived
from the KAME IPsec implementation, but with heavy borrowing and influence
of openbsd. A key feature of this implementation is that it uses the kernel
crypto framework to do all crypto work so when h/w crypto support is present
IPsec operation is automatically accelerated. Otherwise the protocol
implementations are rather differet while the SADB and policy management
code is very similar to KAME (for the moment).

Note that this implementation is enabled with a FAST_IPSEC option. With this
you get all protocols; i.e. there is no FAST_IPSEC_ESP option.

FAST_IPSEC and IPSEC are mutually exclusive; you cannot build both into a
single system.

This software is well tested with IPv4 but should be considered very
experimental (i.e. do not deploy in production environments). This software
does NOT currently support IPv6. In fact do not configure FAST_IPSEC and
INET6 in the same system.

Obtained from: KAME + openbsd
Supported by: Vernier Networks