1 files changed, 967 insertions, 0 deletions

diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
new file mode 100644
index 000000000..178696852
--- /dev/null
+++ b/net/netfilter/xt_hashlimit.c
@@ -0,0 +1,967 @@
+/*
+ *	xt_hashlimit - Netfilter module to limit the number of packets per time
+ *	separately for each hashbucket (sourceip/sourceport/dstip/dstport)
+ *
+ *	(C) 2003-2004 by Harald Welte <laforge@netfilter.org>
+ *	(C) 2006-2012 Patrick McHardy <kaber@trash.net>
+ *	Copyright © CC Computer Consultants GmbH, 2007 - 2008
+ *
+ * Development of this code was funded by Astaro AG, http://www.astaro.com/
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/random.h>
+#include <linux/jhash.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <linux/mm.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+#include <linux/ipv6.h>
+#include <net/ipv6.h>
+#endif
+
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/netfilter/xt_hashlimit.h>
+#include <linux/mutex.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
+MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
+MODULE_ALIAS("ipt_hashlimit");
+MODULE_ALIAS("ip6t_hashlimit");
+
+struct hashlimit_net {
+	struct hlist_head	htables;
+	struct proc_dir_entry	*ipt_hashlimit;
+	struct proc_dir_entry	*ip6t_hashlimit;
+};
+
+static int hashlimit_net_id;
+static inline struct hashlimit_net *hashlimit_pernet(struct net *net)
+{
+	return net_generic(net, hashlimit_net_id);
+}
+
+/* need to declare this at the top */
+static const struct file_operations dl_file_ops;
+
+/* hash table crap */
+struct dsthash_dst {
+	union {
+		struct {
+			__be32 src;
+			__be32 dst;
+		} ip;
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+		struct {
+			__be32 src[4];
+			__be32 dst[4];
+		} ip6;
+#endif
+	};
+	__be16 src_port;
+	__be16 dst_port;
+};
+
+struct dsthash_ent {
+	/* static / read-only parts in the beginning */
+	struct hlist_node node;
+	struct dsthash_dst dst;
+
+	/* modified structure members in the end */
+	spinlock_t lock;
+	unsigned long expires;		/* precalculated expiry time */
+	struct {
+		unsigned long prev;	/* last modification */
+		u_int32_t credit;
+		u_int32_t credit_cap, cost;
+	} rateinfo;
+	struct rcu_head rcu;
+};
+
+struct xt_hashlimit_htable {
+	struct hlist_node node;		/* global list of all htables */
+	int use;
+	u_int8_t family;
+	bool rnd_initialized;
+
+	struct hashlimit_cfg1 cfg;	/* config */
+
+	/* used internally */
+	spinlock_t lock;		/* lock for list_head */
+	u_int32_t rnd;			/* random seed for hash */
+	unsigned int count;		/* number entries in table */
+	struct delayed_work gc_work;
+
+	/* seq_file stuff */
+	struct proc_dir_entry *pde;
+	const char *name;
+	struct net *net;
+
+	struct hlist_head hash[0];	/* hashtable itself */
+};
+
+static DEFINE_MUTEX(hashlimit_mutex);	/* protects htables list */
+static struct kmem_cache *hashlimit_cachep __read_mostly;
+
+static inline bool dst_cmp(const struct dsthash_ent *ent,
+			   const struct dsthash_dst *b)
+{
+	return !memcmp(&ent->dst, b, sizeof(ent->dst));
+}
+
+static u_int32_t
+hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
+{
+	u_int32_t hash = jhash2((const u32 *)dst,
+				sizeof(*dst)/sizeof(u32),
+				ht->rnd);
+	/*
+	 * Instead of returning hash % ht->cfg.size (implying a divide)
+	 * we return the high 32 bits of the (hash * ht->cfg.size) that will
+	 * give results between [0 and cfg.size-1] and same hash distribution,
+	 * but using a multiply, less expensive than a divide
+	 */
+	return reciprocal_scale(hash, ht->cfg.size);
+}
+
+static struct dsthash_ent *
+dsthash_find(const struct xt_hashlimit_htable *ht,
+	     const struct dsthash_dst *dst)
+{
+	struct dsthash_ent *ent;
+	u_int32_t hash = hash_dst(ht, dst);
+
+	if (!hlist_empty(&ht->hash[hash])) {
+		hlist_for_each_entry_rcu(ent, &ht->hash[hash], node)
+			if (dst_cmp(ent, dst)) {
+				spin_lock(&ent->lock);
+				return ent;
+			}
+	}
+	return NULL;
+}
+
+/* allocate dsthash_ent, initialize dst, put in htable and lock it */
+static struct dsthash_ent *
+dsthash_alloc_init(struct xt_hashlimit_htable *ht,
+		   const struct dsthash_dst *dst, bool *race)
+{
+	struct dsthash_ent *ent;
+
+	spin_lock(&ht->lock);
+
+	/* Two or more packets may race to create the same entry in the
+	 * hashtable, double check if this packet lost race.
+	 */
+	ent = dsthash_find(ht, dst);
+	if (ent != NULL) {
+		spin_unlock(&ht->lock);
+		*race = true;
+		return ent;
+	}
+
+	/* initialize hash with random val at the time we allocate
+	 * the first hashtable entry */
+	if (unlikely(!ht->rnd_initialized)) {
+		get_random_bytes(&ht->rnd, sizeof(ht->rnd));
+		ht->rnd_initialized = true;
+	}
+
+	if (ht->cfg.max && ht->count >= ht->cfg.max) {
+		/* FIXME: do something. question is what.. */
+		net_err_ratelimited("max count of %u reached\n", ht->cfg.max);
+		ent = NULL;
+	} else
+		ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
+	if (ent) {
+		memcpy(&ent->dst, dst, sizeof(ent->dst));
+		spin_lock_init(&ent->lock);
+
+		spin_lock(&ent->lock);
+		hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]);
+		ht->count++;
+	}
+	spin_unlock(&ht->lock);
+	return ent;
+}
+
+static void dsthash_free_rcu(struct rcu_head *head)
+{
+	struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
+
+	kmem_cache_free(hashlimit_cachep, ent);
+}
+
+static inline void
+dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
+{
+	hlist_del_rcu(&ent->node);
+	call_rcu_bh(&ent->rcu, dsthash_free_rcu);
+	ht->count--;
+}
+static void htable_gc(struct work_struct *work);
+
+static int htable_create(struct net *net, struct xt_hashlimit_mtinfo1 *minfo,
+			 u_int8_t family)
+{
+	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
+	struct xt_hashlimit_htable *hinfo;
+	unsigned int size;
+	unsigned int i;
+
+	if (minfo->cfg.size) {
+		size = minfo->cfg.size;
+	} else {
+		size = (totalram_pages << PAGE_SHIFT) / 16384 /
+		       sizeof(struct list_head);
+		if (totalram_pages > 1024 * 1024 * 1024 / PAGE_SIZE)
+			size = 8192;
+		if (size < 16)
+			size = 16;
+	}
+	/* FIXME: don't use vmalloc() here or anywhere else -HW */
+	hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
+	                sizeof(struct list_head) * size);
+	if (hinfo == NULL)
+		return -ENOMEM;
+	minfo->hinfo = hinfo;
+
+	/* copy match config into hashtable config */
+	memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
+	hinfo->cfg.size = size;
+	if (hinfo->cfg.max == 0)
+		hinfo->cfg.max = 8 * hinfo->cfg.size;
+	else if (hinfo->cfg.max < hinfo->cfg.size)
+		hinfo->cfg.max = hinfo->cfg.size;
+
+	for (i = 0; i < hinfo->cfg.size; i++)
+		INIT_HLIST_HEAD(&hinfo->hash[i]);
+
+	hinfo->use = 1;
+	hinfo->count = 0;
+	hinfo->family = family;
+	hinfo->rnd_initialized = false;
+	hinfo->name = kstrdup(minfo->name, GFP_KERNEL);
+	if (!hinfo->name) {
+		vfree(hinfo);
+		return -ENOMEM;
+	}
+	spin_lock_init(&hinfo->lock);
+
+	hinfo->pde = proc_create_data(minfo->name, 0,
+		(family == NFPROTO_IPV4) ?
+		hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit,
+		&dl_file_ops, hinfo);
+	if (hinfo->pde == NULL) {
+		kfree(hinfo->name);
+		vfree(hinfo);
+		return -ENOMEM;
+	}
+	hinfo->net = net;
+
+	INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
+	queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
+			   msecs_to_jiffies(hinfo->cfg.gc_interval));
+
+	hlist_add_head(&hinfo->node, &hashlimit_net->htables);
+
+	return 0;
+}
+
+static bool select_all(const struct xt_hashlimit_htable *ht,
+		       const struct dsthash_ent *he)
+{
+	return 1;
+}
+
+static bool select_gc(const struct xt_hashlimit_htable *ht,
+		      const struct dsthash_ent *he)
+{
+	return time_after_eq(jiffies, he->expires);
+}
+
+static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
+			bool (*select)(const struct xt_hashlimit_htable *ht,
+				      const struct dsthash_ent *he))
+{
+	unsigned int i;
+
+	for (i = 0; i < ht->cfg.size; i++) {
+		struct dsthash_ent *dh;
+		struct hlist_node *n;
+
+		spin_lock_bh(&ht->lock);
+		hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
+			if ((*select)(ht, dh))
+				dsthash_free(ht, dh);
+		}
+		spin_unlock_bh(&ht->lock);
+		cond_resched();
+	}
+}
+
+static void htable_gc(struct work_struct *work)
+{
+	struct xt_hashlimit_htable *ht;
+
+	ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
+
+	htable_selective_cleanup(ht, select_gc);
+
+	queue_delayed_work(system_power_efficient_wq,
+			   &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
+}
+
+static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
+{
+	struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
+	struct proc_dir_entry *parent;
+
+	if (hinfo->family == NFPROTO_IPV4)
+		parent = hashlimit_net->ipt_hashlimit;
+	else
+		parent = hashlimit_net->ip6t_hashlimit;
+
+	if (parent != NULL)
+		remove_proc_entry(hinfo->name, parent);
+}
+
+static void htable_destroy(struct xt_hashlimit_htable *hinfo)
+{
+	cancel_delayed_work_sync(&hinfo->gc_work);
+	htable_remove_proc_entry(hinfo);
+	htable_selective_cleanup(hinfo, select_all);
+	kfree(hinfo->name);
+	vfree(hinfo);
+}
+
+static struct xt_hashlimit_htable *htable_find_get(struct net *net,
+						   const char *name,
+						   u_int8_t family)
+{
+	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
+	struct xt_hashlimit_htable *hinfo;
+
+	hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
+		if (!strcmp(name, hinfo->name) &&
+		    hinfo->family == family) {
+			hinfo->use++;
+			return hinfo;
+		}
+	}
+	return NULL;
+}
+
+static void htable_put(struct xt_hashlimit_htable *hinfo)
+{
+	mutex_lock(&hashlimit_mutex);
+	if (--hinfo->use == 0) {
+		hlist_del(&hinfo->node);
+		htable_destroy(hinfo);
+	}
+	mutex_unlock(&hashlimit_mutex);
+}
+
+/* The algorithm used is the Simple Token Bucket Filter (TBF)
+ * see net/sched/sch_tbf.c in the linux source tree
+ */
+
+/* Rusty: This is my (non-mathematically-inclined) understanding of
+   this algorithm.  The `average rate' in jiffies becomes your initial
+   amount of credit `credit' and the most credit you can ever have
+   `credit_cap'.  The `peak rate' becomes the cost of passing the
+   test, `cost'.
+
+   `prev' tracks the last packet hit: you gain one credit per jiffy.
+   If you get credit balance more than this, the extra credit is
+   discarded.  Every time the match passes, you lose `cost' credits;
+   if you don't have that many, the test fails.
+
+   See Alexey's formal explanation in net/sched/sch_tbf.c.
+
+   To get the maximum range, we multiply by this factor (ie. you get N
+   credits per jiffy).  We want to allow a rate as low as 1 per day
+   (slowest userspace tool allows), which means
+   CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
+*/
+#define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
+
+/* Repeated shift and or gives us all 1s, final shift and add 1 gives
+ * us the power of 2 below the theoretical max, so GCC simply does a
+ * shift. */
+#define _POW2_BELOW2(x) ((x)|((x)>>1))
+#define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
+#define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
+#define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
+#define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
+#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
+
+#define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
+
+/* in byte mode, the lowest possible rate is one packet/second.
+ * credit_cap is used as a counter that tells us how many times we can
+ * refill the "credits available" counter when it becomes empty.
+ */
+#define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
+#define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
+
+static u32 xt_hashlimit_len_to_chunks(u32 len)
+{
+	return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
+}
+
+/* Precision saver. */
+static u32 user2credits(u32 user)
+{
+	/* If multiplying would overflow... */
+	if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
+		/* Divide first. */
+		return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
+
+	return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
+}
+
+static u32 user2credits_byte(u32 user)
+{
+	u64 us = user;
+	us *= HZ * CREDITS_PER_JIFFY_BYTES;
+	return (u32) (us >> 32);
+}
+
+static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now, u32 mode)
+{
+	unsigned long delta = now - dh->rateinfo.prev;
+	u32 cap;
+
+	if (delta == 0)
+		return;
+
+	dh->rateinfo.prev = now;
+
+	if (mode & XT_HASHLIMIT_BYTES) {
+		u32 tmp = dh->rateinfo.credit;
+		dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
+		cap = CREDITS_PER_JIFFY_BYTES * HZ;
+		if (tmp >= dh->rateinfo.credit) {/* overflow */
+			dh->rateinfo.credit = cap;
+			return;
+		}
+	} else {
+		dh->rateinfo.credit += delta * CREDITS_PER_JIFFY;
+		cap = dh->rateinfo.credit_cap;
+	}
+	if (dh->rateinfo.credit > cap)
+		dh->rateinfo.credit = cap;
+}
+
+static void rateinfo_init(struct dsthash_ent *dh,
+			  struct xt_hashlimit_htable *hinfo)
+{
+	dh->rateinfo.prev = jiffies;
+	if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
+		dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
+		dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
+		dh->rateinfo.credit_cap = hinfo->cfg.burst;
+	} else {
+		dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
+						   hinfo->cfg.burst);
+		dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
+		dh->rateinfo.credit_cap = dh->rateinfo.credit;
+	}
+}
+
+static inline __be32 maskl(__be32 a, unsigned int l)
+{
+	return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
+}
+
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
+{
+	switch (p) {
+	case 0 ... 31:
+		i[0] = maskl(i[0], p);
+		i[1] = i[2] = i[3] = 0;
+		break;
+	case 32 ... 63:
+		i[1] = maskl(i[1], p - 32);
+		i[2] = i[3] = 0;
+		break;
+	case 64 ... 95:
+		i[2] = maskl(i[2], p - 64);
+		i[3] = 0;
+		break;
+	case 96 ... 127:
+		i[3] = maskl(i[3], p - 96);
+		break;
+	case 128:
+		break;
+	}
+}
+#endif
+
+static int
+hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
+		   struct dsthash_dst *dst,
+		   const struct sk_buff *skb, unsigned int protoff)
+{
+	__be16 _ports[2], *ports;
+	u8 nexthdr;
+	int poff;
+
+	memset(dst, 0, sizeof(*dst));
+
+	switch (hinfo->family) {
+	case NFPROTO_IPV4:
+		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
+			dst->ip.dst = maskl(ip_hdr(skb)->daddr,
+			              hinfo->cfg.dstmask);
+		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
+			dst->ip.src = maskl(ip_hdr(skb)->saddr,
+			              hinfo->cfg.srcmask);
+
+		if (!(hinfo->cfg.mode &
+		      (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
+			return 0;
+		nexthdr = ip_hdr(skb)->protocol;
+		break;
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	case NFPROTO_IPV6:
+	{
+		__be16 frag_off;
+
+		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
+			memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
+			       sizeof(dst->ip6.dst));
+			hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
+		}
+		if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
+			memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
+			       sizeof(dst->ip6.src));
+			hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
+		}
+
+		if (!(hinfo->cfg.mode &
+		      (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
+			return 0;
+		nexthdr = ipv6_hdr(skb)->nexthdr;
+		protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
+		if ((int)protoff < 0)
+			return -1;
+		break;
+	}
+#endif
+	default:
+		BUG();
+		return 0;
+	}
+
+	poff = proto_ports_offset(nexthdr);
+	if (poff >= 0) {
+		ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
+					   &_ports);
+	} else {
+		_ports[0] = _ports[1] = 0;
+		ports = _ports;
+	}
+	if (!ports)
+		return -1;
+	if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
+		dst->src_port = ports[0];
+	if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
+		dst->dst_port = ports[1];
+	return 0;
+}
+
+static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
+{
+	u64 tmp = xt_hashlimit_len_to_chunks(len);
+	tmp = tmp * dh->rateinfo.cost;
+
+	if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
+		tmp = CREDITS_PER_JIFFY_BYTES * HZ;
+
+	if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
+		dh->rateinfo.credit_cap--;
+		dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
+	}
+	return (u32) tmp;
+}
+
+static bool
+hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
+	struct xt_hashlimit_htable *hinfo = info->hinfo;
+	unsigned long now = jiffies;
+	struct dsthash_ent *dh;
+	struct dsthash_dst dst;
+	bool race = false;
+	u32 cost;
+
+	if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
+		goto hotdrop;
+
+	rcu_read_lock_bh();
+	dh = dsthash_find(hinfo, &dst);
+	if (dh == NULL) {
+		dh = dsthash_alloc_init(hinfo, &dst, &race);
+		if (dh == NULL) {
+			rcu_read_unlock_bh();
+			goto hotdrop;
+		} else if (race) {
+			/* Already got an entry, update expiration timeout */
+			dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
+			rateinfo_recalc(dh, now, hinfo->cfg.mode);
+		} else {
+			dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
+			rateinfo_init(dh, hinfo);
+		}
+	} else {
+		/* update expiration timeout */
+		dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
+		rateinfo_recalc(dh, now, hinfo->cfg.mode);
+	}
+
+	if (info->cfg.mode & XT_HASHLIMIT_BYTES)
+		cost = hashlimit_byte_cost(skb->len, dh);
+	else
+		cost = dh->rateinfo.cost;
+
+	if (dh->rateinfo.credit >= cost) {
+		/* below the limit */
+		dh->rateinfo.credit -= cost;
+		spin_unlock(&dh->lock);
+		rcu_read_unlock_bh();
+		return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
+	}
+
+	spin_unlock(&dh->lock);
+	rcu_read_unlock_bh();
+	/* default match is underlimit - so over the limit, we need to invert */
+	return info->cfg.mode & XT_HASHLIMIT_INVERT;
+
+ hotdrop:
+	par->hotdrop = true;
+	return false;
+}
+
+static int hashlimit_mt_check(const struct xt_mtchk_param *par)
+{
+	struct net *net = par->net;
+	struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
+	int ret;
+
+	if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
+		return -EINVAL;
+	if (info->name[sizeof(info->name)-1] != '\0')
+		return -EINVAL;
+	if (par->family == NFPROTO_IPV4) {
+		if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
+			return -EINVAL;
+	} else {
+		if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128)
+			return -EINVAL;
+	}
+
+	if (info->cfg.mode & ~XT_HASHLIMIT_ALL) {
+		pr_info("Unknown mode mask %X, kernel too old?\n",
+						info->cfg.mode);
+		return -EINVAL;
+	}
+
+	/* Check for overflow. */
+	if (info->cfg.mode & XT_HASHLIMIT_BYTES) {
+		if (user2credits_byte(info->cfg.avg) == 0) {
+			pr_info("overflow, rate too high: %u\n", info->cfg.avg);
+			return -EINVAL;
+		}
+	} else if (info->cfg.burst == 0 ||
+		    user2credits(info->cfg.avg * info->cfg.burst) <
+		    user2credits(info->cfg.avg)) {
+			pr_info("overflow, try lower: %u/%u\n",
+				info->cfg.avg, info->cfg.burst);
+			return -ERANGE;
+	}
+
+	mutex_lock(&hashlimit_mutex);
+	info->hinfo = htable_find_get(net, info->name, par->family);
+	if (info->hinfo == NULL) {
+		ret = htable_create(net, info, par->family);
+		if (ret < 0) {
+			mutex_unlock(&hashlimit_mutex);
+			return ret;
+		}
+	}
+	mutex_unlock(&hashlimit_mutex);
+	return 0;
+}
+
+static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
+{
+	const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
+
+	htable_put(info->hinfo);
+}
+
+static struct xt_match hashlimit_mt_reg[] __read_mostly = {
+	{
+		.name           = "hashlimit",
+		.revision       = 1,
+		.family         = NFPROTO_IPV4,
+		.match          = hashlimit_mt,
+		.matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
+		.checkentry     = hashlimit_mt_check,
+		.destroy        = hashlimit_mt_destroy,
+		.me             = THIS_MODULE,
+	},
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	{
+		.name           = "hashlimit",
+		.revision       = 1,
+		.family         = NFPROTO_IPV6,
+		.match          = hashlimit_mt,
+		.matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
+		.checkentry     = hashlimit_mt_check,
+		.destroy        = hashlimit_mt_destroy,
+		.me             = THIS_MODULE,
+	},
+#endif
+};
+
+/* PROC stuff */
+static void *dl_seq_start(struct seq_file *s, loff_t *pos)
+	__acquires(htable->lock)
+{
+	struct xt_hashlimit_htable *htable = s->private;
+	unsigned int *bucket;
+
+	spin_lock_bh(&htable->lock);
+	if (*pos >= htable->cfg.size)
+		return NULL;
+
+	bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
+	if (!bucket)
+		return ERR_PTR(-ENOMEM);
+
+	*bucket = *pos;
+	return bucket;
+}
+
+static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct xt_hashlimit_htable *htable = s->private;
+	unsigned int *bucket = (unsigned int *)v;
+
+	*pos = ++(*bucket);
+	if (*pos >= htable->cfg.size) {
+		kfree(v);
+		return NULL;
+	}
+	return bucket;
+}
+
+static void dl_seq_stop(struct seq_file *s, void *v)
+	__releases(htable->lock)
+{
+	struct xt_hashlimit_htable *htable = s->private;
+	unsigned int *bucket = (unsigned int *)v;
+
+	if (!IS_ERR(bucket))
+		kfree(bucket);
+	spin_unlock_bh(&htable->lock);
+}
+
+static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
+				   struct seq_file *s)
+{
+	const struct xt_hashlimit_htable *ht = s->private;
+
+	spin_lock(&ent->lock);
+	/* recalculate to show accurate numbers */
+	rateinfo_recalc(ent, jiffies, ht->cfg.mode);
+
+	switch (family) {
+	case NFPROTO_IPV4:
+		seq_printf(s, "%ld %pI4:%u->%pI4:%u %u %u %u\n",
+			   (long)(ent->expires - jiffies)/HZ,
+			   &ent->dst.ip.src,
+			   ntohs(ent->dst.src_port),
+			   &ent->dst.ip.dst,
+			   ntohs(ent->dst.dst_port),
+			   ent->rateinfo.credit, ent->rateinfo.credit_cap,
+			   ent->rateinfo.cost);
+		break;
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	case NFPROTO_IPV6:
+		seq_printf(s, "%ld %pI6:%u->%pI6:%u %u %u %u\n",
+			   (long)(ent->expires - jiffies)/HZ,
+			   &ent->dst.ip6.src,
+			   ntohs(ent->dst.src_port),
+			   &ent->dst.ip6.dst,
+			   ntohs(ent->dst.dst_port),
+			   ent->rateinfo.credit, ent->rateinfo.credit_cap,
+			   ent->rateinfo.cost);
+		break;
+#endif
+	default:
+		BUG();
+	}
+	spin_unlock(&ent->lock);
+	return seq_has_overflowed(s);
+}
+
+static int dl_seq_show(struct seq_file *s, void *v)
+{
+	struct xt_hashlimit_htable *htable = s->private;
+	unsigned int *bucket = (unsigned int *)v;
+	struct dsthash_ent *ent;
+
+	if (!hlist_empty(&htable->hash[*bucket])) {
+		hlist_for_each_entry(ent, &htable->hash[*bucket], node)
+			if (dl_seq_real_show(ent, htable->family, s))
+				return -1;
+	}
+	return 0;
+}
+
+static const struct seq_operations dl_seq_ops = {
+	.start = dl_seq_start,
+	.next  = dl_seq_next,
+	.stop  = dl_seq_stop,
+	.show  = dl_seq_show
+};
+
+static int dl_proc_open(struct inode *inode, struct file *file)
+{
+	int ret = seq_open(file, &dl_seq_ops);
+
+	if (!ret) {
+		struct seq_file *sf = file->private_data;
+		sf->private = PDE_DATA(inode);
+	}
+	return ret;
+}
+
+static const struct file_operations dl_file_ops = {
+	.owner   = THIS_MODULE,
+	.open    = dl_proc_open,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = seq_release
+};
+
+static int __net_init hashlimit_proc_net_init(struct net *net)
+{
+	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
+
+	hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
+	if (!hashlimit_net->ipt_hashlimit)
+		return -ENOMEM;
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
+	if (!hashlimit_net->ip6t_hashlimit) {
+		remove_proc_entry("ipt_hashlimit", net->proc_net);
+		return -ENOMEM;
+	}
+#endif
+	return 0;
+}
+
+static void __net_exit hashlimit_proc_net_exit(struct net *net)
+{
+	struct xt_hashlimit_htable *hinfo;
+	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
+
+	/* hashlimit_net_exit() is called before hashlimit_mt_destroy().
+	 * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
+	 * entries is empty before trying to remove it.
+	 */
+	mutex_lock(&hashlimit_mutex);
+	hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
+		htable_remove_proc_entry(hinfo);
+	hashlimit_net->ipt_hashlimit = NULL;
+	hashlimit_net->ip6t_hashlimit = NULL;
+	mutex_unlock(&hashlimit_mutex);
+
+	remove_proc_entry("ipt_hashlimit", net->proc_net);
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+	remove_proc_entry("ip6t_hashlimit", net->proc_net);
+#endif
+}
+
+static int __net_init hashlimit_net_init(struct net *net)
+{
+	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
+
+	INIT_HLIST_HEAD(&hashlimit_net->htables);
+	return hashlimit_proc_net_init(net);
+}
+
+static void __net_exit hashlimit_net_exit(struct net *net)
+{
+	hashlimit_proc_net_exit(net);
+}
+
+static struct pernet_operations hashlimit_net_ops = {
+	.init	= hashlimit_net_init,
+	.exit	= hashlimit_net_exit,
+	.id	= &hashlimit_net_id,
+	.size	= sizeof(struct hashlimit_net),
+};
+
+static int __init hashlimit_mt_init(void)
+{
+	int err;
+
+	err = register_pernet_subsys(&hashlimit_net_ops);
+	if (err < 0)
+		return err;
+	err = xt_register_matches(hashlimit_mt_reg,
+	      ARRAY_SIZE(hashlimit_mt_reg));
+	if (err < 0)
+		goto err1;
+
+	err = -ENOMEM;
+	hashlimit_cachep = kmem_cache_create("xt_hashlimit",
+					    sizeof(struct dsthash_ent), 0, 0,
+					    NULL);
+	if (!hashlimit_cachep) {
+		pr_warn("unable to create slab cache\n");
+		goto err2;
+	}
+	return 0;
+
+err2:
+	xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
+err1:
+	unregister_pernet_subsys(&hashlimit_net_ops);
+	return err;
+
+}
+
+static void __exit hashlimit_mt_exit(void)
+{
+	xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
+	unregister_pernet_subsys(&hashlimit_net_ops);
+
+	rcu_barrier_bh();
+	kmem_cache_destroy(hashlimit_cachep);
+}
+
+module_init(hashlimit_mt_init);
+module_exit(hashlimit_mt_exit);