[NETFILTER]: x_tables: add quota match

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter/xt_quota.h

+#ifndef _XT_QUOTA_H
+#define _XT_QUOTA_H
+
+enum xt_quota_flags {
+	XT_QUOTA_INVERT		= 0x1,
+};
+#define XT_QUOTA_MASK		0x1
+
+struct xt_quota_info {
+	u_int32_t		flags;
+	u_int32_t		pad;
+	aligned_u64		quota;
+	struct xt_quota_info	*master;
+};
+
+#endif /* _XT_QUOTA_H */

net/netfilter/Kconfig

@@ -329,6 +329,16 @@ config NETFILTER_XT_MATCH_PKTTYPE
 
 	  To compile it as a module, choose M here.  If unsure, say N.
 
+config NETFILTER_XT_MATCH_QUOTA
+	tristate '"quota" match support'
+	depends on NETFILTER_XTABLES
+	help
+	  This option adds a `quota' match, which allows to match on a
+	  byte counter.
+
+	  If you want to compile it as a module, say M here and read
+	  <file:Documentation/modules.txt>.  If unsure, say `N'.
+
 config NETFILTER_XT_MATCH_REALM
 	tristate  '"realm" match support'
 	depends on NETFILTER_XTABLES

net/netfilter/Makefile

@@ -44,6 +44,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_MARK) += xt_mark.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_MULTIPORT) += xt_multiport.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_POLICY) += xt_policy.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_PKTTYPE) += xt_pkttype.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_QUOTA) += xt_quota.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_REALM) += xt_realm.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_SCTP) += xt_sctp.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_STATE) += xt_state.o

net/netfilter/xt_quota.c

+/*
+ * netfilter module to enforce network quotas
+ *
+ * Sam Johnston <samj@samj.net>
+ */
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_quota.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
+
+static DEFINE_SPINLOCK(quota_lock);
+
+static int
+match(const struct sk_buff *skb,
+      const struct net_device *in, const struct net_device *out,
+      const struct xt_match *match, const void *matchinfo,
+      int offset, unsigned int protoff, int *hotdrop)
+{
+	struct xt_quota_info *q = ((struct xt_quota_info *)matchinfo)->master;
+	int ret = q->flags & XT_QUOTA_INVERT ? 1 : 0;
+
+	spin_lock_bh(&quota_lock);
+	if (q->quota >= skb->len) {
+		q->quota -= skb->len;
+		ret ^= 1;
+	} else {
+	        /* we do not allow even small packets from now on */
+	        q->quota = 0;
+	}
+	spin_unlock_bh(&quota_lock);
+
+	return ret;
+}
+
+static int
+checkentry(const char *tablename, const void *entry,
+	   const struct xt_match *match, void *matchinfo,
+	   unsigned int matchsize, unsigned int hook_mask)
+{
+	struct xt_quota_info *q = (struct xt_quota_info *)matchinfo;
+
+	if (q->flags & ~XT_QUOTA_MASK)
+		return 0;
+	/* For SMP, we only want to use one set of counters. */
+	q->master = q;
+	return 1;
+}
+
+static struct xt_match quota_match = {
+	.name		= "quota",
+	.family		= AF_INET,
+	.match		= match,
+	.matchsize	= sizeof(struct xt_quota_info),
+	.checkentry	= checkentry,
+	.me		= THIS_MODULE
+};
+
+static struct xt_match quota_match6 = {
+	.name		= "quota",
+	.family		= AF_INET6,
+	.match		= match,
+	.matchsize	= sizeof(struct xt_quota_info),
+	.checkentry	= checkentry,
+	.me		= THIS_MODULE
+};
+
+static int __init xt_quota_init(void)
+{
+	int ret;
+
+	ret = xt_register_match(&quota_match);
+	if (ret)
+		goto err1;
+	ret = xt_register_match(&quota_match6);
+	if (ret)
+		goto err2;
+	return ret;
+
+err2:
+	xt_unregister_match(&quota_match);
+err1:
+	return ret;
+}
+
+static void __exit xt_quota_fini(void)
+{
+	xt_unregister_match(&quota_match6);
+	xt_unregister_match(&quota_match);
+}
+
+module_init(xt_quota_init);
+module_exit(xt_quota_fini);