1 files changed, 92 insertions, 0 deletions
diff --git a/net/netfilter/xt_quota.c b/net/netfilter/xt_quota.c
new file mode 100644
index 000000000..4452cc93b
--- /dev/null
+++ b/net/netfilter/xt_quota.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * netfilter module to enforce network quotas
+ *
+ * Sam Johnston <samj@samj.net>
+ */
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_quota.h>
+#include <linux/module.h>
+
+struct xt_quota_priv {
+	spinlock_t	lock;
+	uint64_t	quota;
+};
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
+MODULE_DESCRIPTION("Xtables: countdown quota match");
+MODULE_ALIAS("ipt_quota");
+MODULE_ALIAS("ip6t_quota");
+
+static bool
+quota_mt(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	struct xt_quota_info *q = (void *)par->matchinfo;
+	struct xt_quota_priv *priv = q->master;
+	bool ret = q->flags & XT_QUOTA_INVERT;
+
+	spin_lock_bh(&priv->lock);
+	if (priv->quota >= skb->len) {
+		priv->quota -= skb->len;
+		ret = !ret;
+	} else {
+		/* we do not allow even small packets from now on */
+		priv->quota = 0;
+	}
+	spin_unlock_bh(&priv->lock);
+
+	return ret;
+}
+
+static int quota_mt_check(const struct xt_mtchk_param *par)
+{
+	struct xt_quota_info *q = par->matchinfo;
+
+	if (q->flags & ~XT_QUOTA_MASK)
+		return -EINVAL;
+
+	q->master = kmalloc(sizeof(*q->master), GFP_KERNEL);
+	if (q->master == NULL)
+		return -ENOMEM;
+
+	spin_lock_init(&q->master->lock);
+	q->master->quota = q->quota;
+	return 0;
+}
+
+static void quota_mt_destroy(const struct xt_mtdtor_param *par)
+{
+	const struct xt_quota_info *q = par->matchinfo;
+
+	kfree(q->master);
+}
+
+static struct xt_match quota_mt_reg __read_mostly = {
+	.name       = "quota",
+	.revision   = 0,
+	.family     = NFPROTO_UNSPEC,
+	.match      = quota_mt,
+	.checkentry = quota_mt_check,
+	.destroy    = quota_mt_destroy,
+	.matchsize  = sizeof(struct xt_quota_info),
+	.usersize   = offsetof(struct xt_quota_info, master),
+	.me         = THIS_MODULE,
+};
+
+static int __init quota_mt_init(void)
+{
+	return xt_register_match(&quota_mt_reg);
+}
+
+static void __exit quota_mt_exit(void)
+{
+	xt_unregister_match(&quota_mt_reg);
+}
+
+module_init(quota_mt_init);
+module_exit(quota_mt_exit);