License cleanup: add SPDX license identifier to uapi header files with no license

Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

netfilter: xt_hashlimit: add rate match mode

This patch adds a new feature to hashlimit that allows matching on the
current packet/byte rate without rate limiting. This can be enabled
with a new flag --hashlimit-rate-match. The match returns true if the
current rate of packets is above/below the user specified value.

The main difference between the existing algorithm and the new one is
that the existing algorithm rate-limits the flow whereas the new
algorithm does not. Instead it *classifies* the flow based on whether
it is above or below a certain rate. I will demonstrate this with an
example below. Let us assume this rule:

iptables -A INPUT -m hashlimit --hashlimit-above 10/s -j new_chain

If the packet rate is 15/s, the existing algorithm would ACCEPT 10
packets every second and send 5 packets to "new_chain".

But with the new algorithm, as long as the rate of 15/s is sustained,
all packets will continue to match and every packet is sent to new_chain.

This new functionality will let us classify different flows based on
their current rate, so that further decisions can be made on them based on
what the current rate is.

This is how the new algorithm works:
We divide time into intervals of 1 (sec/min/hour) as specified by
the user. We keep track of the number of packets/bytes processed in the
current interval. After each interval we reset the counter to 0.

When we receive a packet for match, we look at the packet rate
during the current interval and the previous interval to make a
decision:

if [ prev_rate < user and cur_rate < user ]
return Below
else
return Above

Where cur_rate is the number of packets/bytes seen in the current
interval, prev is the number of packets/bytes seen in the previous
interval and 'user' is the rate specified by the user.

We also provide flexibility to the user for choosing the time
interval using the option --hashilmit-interval. For example the user can
keep a low rate like x/hour but still keep the interval as small as 1
second.

To preserve backwards compatibility we have to add this feature in a new
revision, so I've created revision 3 for hashlimit. The two new options
we add are:

--hashlimit-rate-match
--hashlimit-rate-interval

I have updated the help text to add these new options. Also added a few
tests for the new options.

Suggested-by: Igor Lubashev <ilubashe@akamai.com>
Reviewed-by: Josh Hunt <johunt@akamai.com>
Signed-off-by: Vishwanath Pai <vpai@akamai.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

uapi: fix linux/netfilter/xt_hashlimit.h userspace compilation error

Include <linux/limits.h> like some of uapi/linux/netfilter/xt_*.h
headers do to fix the following linux/netfilter/xt_hashlimit.h
userspace compilation error:

/usr/include/linux/netfilter/xt_hashlimit.h:90:12: error: 'NAME_MAX' undeclared here (not in a function)
char name[NAME_MAX];

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: xt_hashlimit: Create revision 2 to support higher pps rates

Create a new revision for the hashlimit iptables extension module. Rev 2
will support higher pps of upto 1 million, Version 1 supports only 10k.

To support this we have to increase the size of the variables avg and
burst in hashlimit_cfg to 64-bit. Create two new structs hashlimit_cfg2
and xt_hashlimit_mtinfo2 and also create newer versions of all the
functions for match, checkentry and destroy.

Some of the functions like hashlimit_mt, hashlimit_mt_check etc are very
similar in both rev1 and rev2 with only minor changes, so I have split
those functions and moved all the common code to a *_common function.

Signed-off-by: Vishwanath Pai <vpai@akamai.com>
Signed-off-by: Joshua Hunt <johunt@akamai.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: fix include files for compilation

Add missing header dependencies and other small changes so that each file
compiles alone in userspace.

Signed-off-by: Mikko Rapeli <mikko.rapeli@iki.fi>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

UAPI: (Scripted) Disintegrate include/linux/netfilter

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>