- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r286140:
Remove the sleep from the buffer allocation routine.

The buffer must be allocated (or even changed) before the interface is set
and thus, there is no need to verify if the buffer is in use.

MFC r286142:
Remove two unnecessary sleeps from the hot path in bpf(4).

The first one never triggers because bpf_canfreebuf() can only be true for
zero-copy buffers and zero-copy buffers are not read with read(2).

The second also never triggers, because we check the free buffer before
calling ROTATE_BUFFERS(). If the hold buffer is in use the free buffer
will be NULL and there is nothing else to do besides drop the packet. If
the free buffer isn't NULL the hold buffer _is_ free and it is safe to
rotate the buffers.

Update the comment in ROTATE_BUFFERS macro to match the logic described
here.

While here fix a few typos in comments.

MFC r286243:
Add a KASSERT() to make sure we wont rotate the buffers twice (rotate the
buffers while the hold buffer is in use).

Sponsored by: Rubicon Communications (Netgate)

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

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

Changes to resolve races in bpfread() and catchpacket() that, at worst,
cause kernel panics.

Add a flag to the bpf descriptor to indicate whether the hold buffer
is in use. In bpfread(), set the "hold buffer in use" flag before
dropping the descriptor lock during the call to bpf_uiomove().
Everywhere else the hold buffer is used or changed, wait while
the hold buffer is in use by bpfread(). Add a KASSERT in bpfread()
after re-acquiring the descriptor lock to assist uncovering any
additional hold buffer races.

Call bpf_jitter() before acquiring BPF global lock due to malloc() being used inside bpf_jitter.

Eliminate bpf_buffer_alloc() and allocate BPF buffers on descriptor creation and BIOCSBLEN ioctl.
This permits us not to allocate buffers inside bpf_attachd() which is protected by global lock.

Approved by: kib(mentor)
MFC in: 4 weeks

Fix old panic when BPF consumer attaches to destroying interface.
'flags' field is added to the end of bpf_if structure. Currently the only
flag is BPFIF_FLAG_DYING which is set on bpf detach and checked by bpf_attachd()
Problem can be easily triggered on SMP stable/[89] by the following command (sort of):
'while true; do ifconfig vlan222 create vlan 222 vlandev em0 up ; tcpdump -pi vlan222 & ; ifconfig vlan222 destroy ; done'

Fix possible use-after-free when BPF detaches itself from interface, freeing bpf_bif memory,
while interface is still UP and there can be routes via this interface.
Freeing is now delayed till ifnet_departure_event is received via eventhandler(9) api.

Convert bpfd rwlock back to mutex due lack of performance gain (currently checking if packet
matches filter is done without holding bpfd lock and we have to acquire write lock if packet matches)

Approved by: kib(mentor)
MFC in: 4 weeks

- Improve BPF locking model.

Interface locks and descriptor locks are converted from mutex(9) to rwlock(9).
This greately improves performance: in most common case we need to acquire 1
reader lock instead of 2 mutexes.

- Remove filter(descriptor) (reader) lock in bpf_mtap[2]
This was suggested by glebius@. We protect filter by requesting interface
writer lock on filter change.

- Cover struct bpf_if under BPF_INTERNAL define. This permits including bpf.h
without including rwlock stuff. However, this is is temporary solution,
struct bpf_if should be made opaque for any external caller.

Found by: Dmitrij Tejblum <tejblum@yandex-team.ru>
Sponsored by: Yandex LLC

Reviewed by: glebius (previous version)
Reviewed by: silence on -net@
Approved by: (mentor)

MFC after: 3 weeks

- Fix trivial typo

Approved by: nwhitehorn
MFC after: 3 days

o Swap descriptions for net.bpf.bufsize and net.bpf.maxbufsize.

PR: misc/152531
MFC after: 1 week

Always embed pointer to BPF JIT function in BPF descriptor
to avoid inconsistency when opt_bpf.h is not included.

Reviewed by: rwatson
Approved by: re (rwatson)

Fill in BPF sysctl descriptions.

Reviewed by: csjp

Fix build with option BPF_JITTER.

Introduce support for zero-copy BPF buffering, which reduces the
overhead of packet capture by allowing a user process to directly "loan"
buffer memory to the kernel rather than using read(2) to explicitly copy
data from kernel address space.

The user process will issue new BPF ioctls to set the shared memory
buffer mode and provide pointers to buffers and their size. The kernel
then wires and maps the pages into kernel address space using sf_buf(9),
which on supporting architectures will use the direct map region. The
current "buffered" access mode remains the default, and support for
zero-copy buffers must, for the time being, be explicitly enabled using
a sysctl for the kernel to accept requests to use it.

The kernel and user process synchronize use of the buffers with atomic
operations, avoiding the need for system calls under load; the user
process may use select()/poll()/kqueue() to manage blocking while
waiting for network data if the user process is able to consume data
faster than the kernel generates it. Patchs to libpcap are available
to allow libpcap applications to transparently take advantage of this
support. Detailed information on the new API may be found in bpf(4),
including specific atomic operations and memory barriers required to
synchronize buffer use safely.

These changes modify the base BPF implementation to (roughly) abstrac
the current buffer model, allowing the new shared memory model to be
added, and add new monitoring statistics for netstat to print. The
implementation, with the exception of some monitoring hanges that break
the netstat monitoring ABI for BPF, will be MFC'd.

Zerocopy bpf buffers are still considered experimental are disabled
by default. To experiment with this new facility, adjust the
net.bpf.zerocopy_enable sysctl variable to 1.

Changes to libpcap will be made available as a patch for the time being,
and further refinements to the implementation are expected.

Sponsored by: Seccuris Inc.
In collaboration with: rwatson
Tested by: pwood, gallatin
MFC after: 4 months [1]

[1] Certain portions will probably not be MFCed, specifically things
that can break the monitoring ABI.