[NETFILTER]: x_tables: add quota match

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

3 files changed, 107 insertions, 0 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index e2893effdfaa..5543c7b74535 100644
--- a/net/netfilter/Kconfig
+++ b/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
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 95b7e416512d..4b6a6ea07373 100644
--- a/net/netfilter/Makefile
+++ b/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
diff --git a/net/netfilter/xt_quota.c b/net/netfilter/xt_quota.c
new file mode 100644
index 000000000000..4cdba7469dc4
--- /dev/null
+++ b/net/netfilter/xt_quota.c
@@ -0,0 +1,96 @@
+/*
+ * 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);