Adding the original quota2 from xtables-addons

The original xt_quota in the kernel is plain broken:
  - counts quota at a per CPU level
    (was written back when ubiquitous SMP was just a dream)
  - provides no way to count across IPV4/IPV6.

This patch is the original unaltered code from:
  http://sourceforge.net/projects/xtables-addons
at commit e84391ce665cef046967f796dd91026851d6bbf3

Change-Id: Ia8b21394ea79ef55514748e96f769e40355a6ccf
Signed-off-by: JP Abgrall <jpa@google.com>

3 files changed, 215 insertions, 0 deletions

diff --git a/extensions/libxt_quota2.c b/extensions/libxt_quota2.c
new file mode 100644
index 00000000..3763251b
--- /dev/null
+++ b/extensions/libxt_quota2.c
@@ -0,0 +1,153 @@
+/*
+ *	"quota2" match extension for iptables
+ *	Sam Johnston <samj [at] samj net>
+ *	Jan Engelhardt <jengelh [at] medozas de>, 2008
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License; either
+ *	version 2 of the License, or any later version, as published by the
+ *	Free Software Foundation.
+ */
+#include <getopt.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <xtables.h>
+#include "xt_quota2.h"
+#include "compat_user.h"
+
+enum {
+	FL_QUOTA     = 1 << 0,
+	FL_NAME      = 1 << 1,
+	FL_GROW      = 1 << 2,
+	FL_PACKET    = 1 << 3,
+	FL_NO_CHANGE = 1 << 4,
+};
+
+static const struct option quota_mt2_opts[] = {
+	{.name = "grow",      .has_arg = false, .val = 'g'},
+	{.name = "no-change", .has_arg = false, .val = 'c'},
+	{.name = "name",      .has_arg = true,  .val = 'n'},
+	{.name = "quota",     .has_arg = true,  .val = 'q'},
+	{.name = "packets",   .has_arg = false, .val = 'p'},
+	{NULL},
+};
+
+static void quota_mt2_help(void)
+{
+	printf(
+	"quota match options:\n"
+	"    --grow           provide an increasing counter\n"
+	"    --no-change      never change counter/quota value for matching packets\n"
+	"    --name name      name for the file in sysfs\n"
+	"[!] --quota quota    initial quota (bytes or packets)\n"
+	"    --packets        count packets instead of bytes\n"
+	);
+}
+
+static int
+quota_mt2_parse(int c, char **argv, int invert, unsigned int *flags,
+	        const void *entry, struct xt_entry_match **match)
+{
+	struct xt_quota_mtinfo2 *info = (void *)(*match)->data;
+	char *end;
+
+	switch (c) {
+	case 'g':
+		xtables_param_act(XTF_ONLY_ONCE, "quota", "--grow", *flags & FL_GROW);
+		xtables_param_act(XTF_NO_INVERT, "quota", "--grow", invert);
+		info->flags |= XT_QUOTA_GROW;
+		*flags |= FL_GROW;
+		return true;
+	case 'c': /* no-change */
+		xtables_param_act(XTF_ONLY_ONCE, "quota", "--no-change", *flags & FL_NO_CHANGE);
+		xtables_param_act(XTF_NO_INVERT, "quota", "--no-change", invert);
+		info->flags |= XT_QUOTA_NO_CHANGE;
+		*flags |= FL_NO_CHANGE;
+		return true;
+	case 'n':
+		/* zero termination done on behalf of the kernel module */
+		xtables_param_act(XTF_ONLY_ONCE, "quota", "--name", *flags & FL_NAME);
+		xtables_param_act(XTF_NO_INVERT, "quota", "--name", invert);
+		strncpy(info->name, optarg, sizeof(info->name));
+		*flags |= FL_NAME;
+		return true;
+	case 'p':
+		xtables_param_act(XTF_ONLY_ONCE, "quota", "--packets", *flags & FL_PACKET);
+		xtables_param_act(XTF_NO_INVERT, "quota", "--packets", invert);
+		info->flags |= XT_QUOTA_PACKET;
+		*flags |= FL_PACKET;
+		return true;
+	case 'q':
+		xtables_param_act(XTF_ONLY_ONCE, "quota", "--quota", *flags & FL_QUOTA);
+		if (invert)
+			info->flags |= XT_QUOTA_INVERT;
+		info->quota = strtoull(optarg, &end, 0);
+		if (*end != '\0')
+			xtables_error(PARAMETER_PROBLEM, "quota match: "
+			           "invalid value for --quota");
+		*flags |= FL_QUOTA;
+		return true;
+	}
+	return false;
+}
+
+static void
+quota_mt2_save(const void *ip, const struct xt_entry_match *match)
+{
+	const struct xt_quota_mtinfo2 *q = (void *)match->data;
+
+	if (q->flags & XT_QUOTA_INVERT)
+		printf(" !");
+	if (q->flags & XT_QUOTA_GROW)
+		printf(" --grow ");
+	if (q->flags & XT_QUOTA_NO_CHANGE)
+		printf(" --no-change ");
+	if (q->flags & XT_QUOTA_PACKET)
+		printf(" --packets ");
+	if (*q->name != '\0')
+		printf(" --name %s ", q->name);
+	printf(" --quota %llu ", (unsigned long long)q->quota);
+}
+
+static void quota_mt2_print(const void *ip, const struct xt_entry_match *match,
+                            int numeric)
+{
+	const struct xt_quota_mtinfo2 *q = (const void *)match->data;
+
+	if (q->flags & XT_QUOTA_INVERT)
+		printf(" !");
+	if (q->flags & XT_QUOTA_GROW)
+		printf(" counter");
+	else
+		printf(" quota");
+	if (*q->name != '\0')
+		printf(" %s:", q->name);
+	printf(" %llu ", (unsigned long long)q->quota);
+	if (q->flags & XT_QUOTA_PACKET)
+		printf("packets ");
+	else
+		printf("bytes ");
+	if (q->flags & XT_QUOTA_NO_CHANGE)
+		printf("(no-change mode) ");
+}
+
+static struct xtables_match quota_mt2_reg = {
+	.family        = NFPROTO_UNSPEC,
+	.revision      = 3,
+	.name          = "quota2",
+	.version       = XTABLES_VERSION,
+	.size          = XT_ALIGN(sizeof (struct xt_quota_mtinfo2)),
+	.userspacesize = offsetof(struct xt_quota_mtinfo2, quota),
+	.help          = quota_mt2_help,
+	.parse         = quota_mt2_parse,
+	.print         = quota_mt2_print,
+	.save          = quota_mt2_save,
+	.extra_opts    = quota_mt2_opts,
+};
+
+static __attribute__((constructor)) void quota2_mt_ldr(void)
+{
+	xtables_register_match(&quota_mt2_reg);
+}
diff --git a/extensions/libxt_quota2.man b/extensions/libxt_quota2.man
new file mode 100644
index 00000000..c2e6b44d
--- /dev/null
+++ b/extensions/libxt_quota2.man
@@ -0,0 +1,37 @@
+The "quota2" implements a named counter which can be increased or decreased
+on a per-match basis. Available modes are packet counting or byte counting.
+The value of the counter can be read and reset through procfs, thereby making
+this match a minimalist accounting tool.
+.PP
+When counting down from the initial quota, the counter will stop at 0 and
+the match will return false, just like the original "quota" match. In growing
+(upcounting) mode, it will always return true.
+.TP
+\fB\-\-grow\fP
+Count upwards instead of downwards.
+.TP
+\fB\-\-no\-change\fP
+Makes it so the counter or quota amount is never changed by packets matching
+this rule. This is only really useful in "quota" mode, as it will allow you to
+use complex prerouting rules in association with the quota system, without
+counting a packet twice.
+.TP
+\fB\-\-name\fP \fIname\fP
+Assign the counter a specific name. This option must be present, as an empty
+name is not allowed. Names starting with a dot or names containing a slash are
+prohibited.
+.TP
+[\fB!\fP] \fB\-\-quota\fP \fIiq\fP
+Specify the initial quota for this counter. If the counter already exists,
+it is not reset. An "!" may be used to invert the result of the match. The
+negation has no effect when \fB\-\-grow\fP is used.
+.TP
+\fB\-\-packets\fP
+Count packets instead of bytes that passed the quota2 match.
+.PP
+Because counters in quota2 can be shared, you can combine them for various
+purposes, for example, a bytebucket filter that only lets as much traffic go
+out as has come in:
+.PP
+\-A INPUT \-p tcp \-\-dport 6881 \-m quota \-\-name bt \-\-grow;
+\-A OUTPUT \-p tcp \-\-sport 6881 \-m quota \-\-name bt;
diff --git a/include/linux/netfilter/xt_quota2.h b/include/linux/netfilter/xt_quota2.h
new file mode 100644
index 00000000..eadc6903
--- /dev/null
+++ b/include/linux/netfilter/xt_quota2.h
@@ -0,0 +1,25 @@
+#ifndef _XT_QUOTA_H
+#define _XT_QUOTA_H
+
+enum xt_quota_flags {
+	XT_QUOTA_INVERT    = 1 << 0,
+	XT_QUOTA_GROW      = 1 << 1,
+	XT_QUOTA_PACKET    = 1 << 2,
+	XT_QUOTA_NO_CHANGE = 1 << 3,
+	XT_QUOTA_MASK      = 0x0F,
+};
+
+struct xt_quota_counter;
+
+struct xt_quota_mtinfo2 {
+	char name[15];
+	u_int8_t flags;
+
+	/* Comparison-invariant */
+	aligned_u64 quota;
+
+	/* Used internally by the kernel */
+	struct xt_quota_counter *master __attribute__((aligned(8)));
+};
+
+#endif /* _XT_QUOTA_H */