'RELENG_6_0_0_RELEASE'.

This commit was manufactured to restore the state of the 6.0-RELEASE image.

default elements in net_init_domain().

This makes it possible to grep these structures and see any bogosities.

(sorele()/sotryfree()):

- This permits the caller to acquire the accept mutex before the socket
  mutex, avoiding sofree() having to drop the socket mutex and re-order,
  which could lead to races permitting more than one thread to enter
  sofree() after a socket is ready to be free'd.

- This also covers clearing of the so_pcb weak socket reference from
  the protocol to the socket, preventing races in clearing and
  evaluation of the reference such that sofree() might be called more
  than once on the same socket.

This appears to close a race I was able to easily trigger by repeatedly
opening and resetting TCP connections to a host, in which the
tcp_close() code called as a result of the RST raced with the close()
of the accepted socket in the user process resulting in simultaneous
attempts to de-allocate the same socket.  The new locking increases
the overhead for operations that may potentially free the socket, so we
will want to revise the synchronization strategy here as we normalize
the reference counting model for sockets.  The use of the accept mutex
in freeing of sockets that are not listen sockets is primarily
motivated by the potential need to remove the socket from the
incomplete connection queue on its parent (listen) socket, so cleaning
up the reference model here may allow us to substantially weaken the
synchronization requirements.

RELENG_5_3 candidate.

MFC after:	3 days
Reviewed by:	dwhite
Discussed with:	gnn, dwhite, green
Reported by:	Marc UBM Bocklet <ubm at u-boot-man dot de>
Reported by:	Vlad <marchenko at gmail dot com>

using rawcb_mtx.  Hold this mutex while modifying or iterating over
the control list; this means that the mutex is held over calls into
socket delivery code, which no longer causes a lock order reversal as
the routing socket code uses a netisr to avoid recursing socket ->
routing -> socket.

Note: Locking of IPsec consumers of rawcb_list is not included in this
commit.

reference count:

- Assert SOCK_LOCK(so) macros that directly manipulate so_count:
  soref(), sorele().

- Assert SOCK_LOCK(so) in macros/functions that rely on the state of
  so_count: sofree(), sotryfree().

- Acquire SOCK_LOCK(so) before calling these functions or macros in
  various contexts in the stack, both at the socket and protocol
  layers.

- In some cases, perform soisdisconnected() before sotryfree(), as
  this could result in frobbing of a non-present socket if
  sotryfree() actually frees the socket.

- Note that sofree()/sotryfree() will release the socket lock even if
  they don't free the socket.

Submitted by:	sam
Sponsored by:	FreeBSD Foundation
Obtained from:	BSD/OS

license, per letter dated July 22, 1999 and email from Peter Wemm,
Alan Cox and Robert Watson.

Approved by: core, peter, alc, rwatson

functions in kern_socket.c.

Rename the "canwait" field to "mflags" and pass M_WAITOK and M_NOWAIT
in from the caller context rather than "1" or "0".

Correct mflags pass into mac_init_socket() from previous commit to not
include M_ZERO.

Submitted by:	sam

the   MAC label referenced from 'struct socket' in the IPv4 and
IPv6-based protocols.  This permits MAC labels to be checked during
network delivery operations without dereferencing inp->inp_socket
to get to so->so_label, which will eventually avoid our having to
grab the socket lock during delivery at the network layer.

This change introduces 'struct inpcb' as a labeled object to the
MAC Framework, along with the normal circus of entry points:
initialization, creation from socket, destruction, as well as a
delivery access control check.

For most policies, the inpcb label will simply be a cache of the
socket label, so a new protocol switch method is introduced,
pr_sosetlabel() to notify protocols that the socket layer label
has been updated so that the cache can be updated while holding
appropriate locks.  Most protocols implement this using
pru_sosetlabel_null(), but IPv4/IPv6 protocols using inpcbs use
the the worker function in_pcbsosetlabel(), which calls into the
MAC Framework to perform a cache update.

Biba, LOMAC, and MLS implement these entry points, as do the stub
policy, and test policy.

Reviewed by:	sam, bms
Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, Network Associates Laboratories