[nf-next,v2,7/7] netfilter: nf_tables: add bitmap set type

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index dfbe9deeb8c4..ea479ed43373 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -509,6 +509,12 @@  config NFT_SET_HASH
 	  This option adds the "hash" set type that is used to build one-way
 	  mappings between matchings and actions.
 
+config NFT_SET_BITMAP
+	tristate "Netfilter nf_tables bitmap set module"
+	help
+	  This option adds the "bitmap" set type that is used to build sets
+	  whose keys are smaller or equal to 16 bits.
+
 config NFT_COUNTER
 	tristate "Netfilter nf_tables counter module"
 	help
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 6b3034f12661..c9b78e7b342f 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -93,6 +93,7 @@  obj-$(CONFIG_NFT_REJECT) 	+= nft_reject.o
 obj-$(CONFIG_NFT_REJECT_INET)	+= nft_reject_inet.o
 obj-$(CONFIG_NFT_SET_RBTREE)	+= nft_set_rbtree.o
 obj-$(CONFIG_NFT_SET_HASH)	+= nft_set_hash.o
+obj-$(CONFIG_NFT_SET_BITMAP)	+= nft_set_bitmap.o
 obj-$(CONFIG_NFT_COUNTER)	+= nft_counter.o
 obj-$(CONFIG_NFT_LOG)		+= nft_log.o
 obj-$(CONFIG_NFT_MASQ)		+= nft_masq.o
diff --git a/net/netfilter/nft_set_bitmap.c b/net/netfilter/nft_set_bitmap.c
new file mode 100644
index 000000000000..97f9649bcc7e
--- /dev/null
+++ b/net/netfilter/nft_set_bitmap.c
@@ -0,0 +1,314 @@ 
+/*
+ * Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables.h>
+
+/* This bitmap uses two bits to represent one element. These two bits determine
+ * the element state in the current and the future generation.
+ *
+ * An element can be in three states. The generation cursor is represented using
+ * the ^ character, note that this cursor shifts on every succesful transaction.
+ * If no transaction is going on, we observe all elements are in the following
+ * state:
+ *
+ * 11 = this element is active in the current generation. In case of no updates,
+ * ^    it stays active in the next generation.
+ * 00 = this element is inactive in the current generation. In case of no
+ * ^    updates, it stays inactive in the next generation.
+ *
+ * On transaction handling, we observe these two temporary states:
+ *
+ * 01 = this element is inactive in the current generation and it becomes active
+ * ^    in the next one. This happens when the element is inserted but commit
+ *      path has not yet been executed yet, so activation is still pending. On
+ *      transaction abortion, the element is removed.
+ * 10 = this element is active in the current generation and it becomes inactive
+ * ^    in the next one. This happens when the element is deactivated but commit
+ *      path has not yet been executed yet, so removal is still pending. On
+ *      transation abortion, the next generation bit is reset to go back to
+ *      restore its previous state.
+ */
+struct nft_bitmap {
+	u16	bitmap_size;
+	u8	bitmap[];
+};
+
+static inline void nft_bitmap_location(u32 key, u32 *idx, u32 *off)
+{
+	u32 k = (key << 1);
+
+	*idx = k / BITS_PER_BYTE;
+	*off = k % BITS_PER_BYTE;
+}
+
+/* Fetch the two bits that represent the element and check if it is active based
+ * on the generation mask.
+ */
+static inline bool
+nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask)
+{
+	return (bitmap[idx] & (0x3 << off)) & (genmask << off);
+}
+
+static bool nft_bitmap_lookup(const struct net *net, const struct nft_set *set,
+			      const u32 *key, const struct nft_set_ext **ext)
+{
+	const struct nft_bitmap *priv = nft_set_priv(set);
+	u8 genmask = nft_genmask_cur(net);
+	u32 idx, off;
+
+	nft_bitmap_location(*key, &idx, &off);
+
+	return nft_bitmap_active(priv->bitmap, idx, off, genmask);
+}
+
+static int nft_bitmap_insert(const struct net *net, const struct nft_set *set,
+			     const struct nft_set_elem *elem,
+			     struct nft_set_ext **_ext)
+{
+	struct nft_bitmap *priv = nft_set_priv(set);
+	struct nft_set_ext *ext = elem->priv;
+	u8 genmask = nft_genmask_next(net);
+	u32 idx, off;
+
+	nft_bitmap_location(nft_set_ext_key(ext)->data[0], &idx, &off);
+	if (nft_bitmap_active(priv->bitmap, idx, off, genmask))
+		return -EEXIST;
+
+	/* Enter 01 state. */
+	priv->bitmap[idx] |= (genmask << off);
+
+	return 0;
+}
+
+static void nft_bitmap_remove(const struct net *net,
+			      const struct nft_set *set,
+			      const struct nft_set_elem *elem)
+{
+	struct nft_bitmap *priv = nft_set_priv(set);
+	struct nft_set_ext *ext = elem->priv;
+	u8 genmask = nft_genmask_next(net);
+	u32 idx, off;
+
+	nft_bitmap_location(nft_set_ext_key(ext)->data[0], &idx, &off);
+	/* Enter 00 state. */
+	priv->bitmap[idx] &= ~(genmask << off);
+}
+
+static void nft_bitmap_activate(const struct net *net,
+				const struct nft_set *set,
+				const struct nft_set_elem *elem)
+{
+	struct nft_bitmap *priv = nft_set_priv(set);
+	struct nft_set_ext *ext = elem->priv;
+	u8 genmask = nft_genmask_next(net);
+	u32 idx, off;
+
+	nft_bitmap_location(nft_set_ext_key(ext)->data[0], &idx, &off);
+	/* Enter 11 state. */
+	priv->bitmap[idx] |= (genmask << off);
+}
+
+static bool nft_bitmap_flush(const struct net *net,
+			     const struct nft_set *set, void *ext)
+{
+	struct nft_bitmap *priv = nft_set_priv(set);
+	u8 genmask = nft_genmask_next(net);
+	u32 idx, off;
+
+	nft_bitmap_location(nft_set_ext_key(ext)->data[0], &idx, &off);
+	/* Enter 10 state, similar to deactivation. */
+	priv->bitmap[idx] &= ~(genmask << off);
+
+	return true;
+}
+
+static struct nft_set_ext *nft_bitmap_ext_alloc(const struct nft_set *set,
+						const struct nft_set_elem *elem)
+{
+	struct nft_set_ext_tmpl tmpl;
+	struct nft_set_ext *ext;
+
+	nft_set_ext_prepare(&tmpl);
+	nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen);
+
+	ext = kzalloc(tmpl.len, GFP_KERNEL);
+	if (!ext)
+		return NULL;
+
+	nft_set_ext_init(ext, &tmpl);
+	memcpy(nft_set_ext_key(ext), elem->key.val.data, set->klen);
+
+	return ext;
+}
+
+static void *nft_bitmap_deactivate(const struct net *net,
+				   const struct nft_set *set,
+				   const struct nft_set_elem *elem)
+{
+	struct nft_bitmap *priv = nft_set_priv(set);
+	u8 genmask = nft_genmask_next(net);
+	struct nft_set_ext *ext;
+	u32 idx, off, key = 0;
+
+	memcpy(&key, elem->key.val.data, set->klen);
+	nft_bitmap_location(key, &idx, &off);
+
+	if (!nft_bitmap_active(priv->bitmap, idx, off, genmask))
+		return NULL;
+
+	/* We have no real set extension since this is a bitmap, allocate this
+	 * dummy object that is released from the commit/abort path.
+	 */
+	ext = nft_bitmap_ext_alloc(set, elem);
+	if (!ext)
+		return NULL;
+
+	/* Enter 10 state. */
+	priv->bitmap[idx] &= ~(genmask << off);
+
+	return ext;
+}
+
+static void nft_bitmap_walk(const struct nft_ctx *ctx,
+			    struct nft_set *set,
+			    struct nft_set_iter *iter)
+{
+	const struct nft_bitmap *priv = nft_set_priv(set);
+	struct nft_set_ext_tmpl tmpl;
+	struct nft_set_elem elem;
+	struct nft_set_ext *ext;
+	int idx, off;
+	u16 key;
+
+	nft_set_ext_prepare(&tmpl);
+	nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen);
+
+	for (idx = 0; idx < priv->bitmap_size; idx++) {
+		for (off = 0; off < BITS_PER_BYTE; off += 2) {
+			if (iter->count < iter->skip)
+				goto cont;
+
+			if (!nft_bitmap_active(priv->bitmap, idx, off,
+					       iter->genmask))
+				goto cont;
+
+			ext = kzalloc(tmpl.len, GFP_KERNEL);
+			if (!ext) {
+				iter->err = -ENOMEM;
+				return;
+			}
+			nft_set_ext_init(ext, &tmpl);
+			key = ((idx * BITS_PER_BYTE) + off) >> 1;
+			memcpy(nft_set_ext_key(ext), &key, set->klen);
+
+			elem.priv = ext;
+			iter->err = iter->fn(ctx, set, iter, &elem);
+
+			/* On set flush, this dummy extension object is released
+			 * from the commit/abort path.
+			 */
+			if (!iter->flush)
+				kfree(ext);
+
+			if (iter->err < 0)
+				return;
+cont:
+			iter->count++;
+		}
+	}
+}
+
+/* The bitmap size is pow(2, key length in bits) / bits per byte. This is
+ * multiplied by two since each element takes two bits. For 8 bit keys, the
+ * bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
+ */
+static inline u32 nft_bitmap_size(u32 klen)
+{
+	return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
+}
+
+static inline u32 nft_bitmap_total_size(u32 klen)
+{
+	return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
+}
+
+static unsigned int nft_bitmap_privsize(const struct nlattr * const nla[])
+{
+	u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
+
+	return nft_bitmap_total_size(klen);
+}
+
+static int nft_bitmap_init(const struct nft_set *set,
+			 const struct nft_set_desc *desc,
+			 const struct nlattr * const nla[])
+{
+	struct nft_bitmap *priv = nft_set_priv(set);
+
+	priv->bitmap_size = nft_bitmap_total_size(set->klen);
+
+	return 0;
+}
+
+static void nft_bitmap_destroy(const struct nft_set *set)
+{
+}
+
+static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
+				struct nft_set_estimate *est)
+{
+	/* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
+	if (desc->klen > 2)
+		return false;
+
+	est->size   = nft_bitmap_total_size(desc->klen);
+	est->lookup = NFT_SET_CLASS_O_1;
+	est->space  = NFT_SET_CLASS_O_1;
+
+	return true;
+}
+
+static struct nft_set_ops nft_bitmap_ops __read_mostly = {
+	.privsize	= nft_bitmap_privsize,
+	.estimate	= nft_bitmap_estimate,
+	.init		= nft_bitmap_init,
+	.destroy	= nft_bitmap_destroy,
+	.insert		= nft_bitmap_insert,
+	.remove		= nft_bitmap_remove,
+	.deactivate	= nft_bitmap_deactivate,
+	.flush		= nft_bitmap_flush,
+	.activate	= nft_bitmap_activate,
+	.lookup		= nft_bitmap_lookup,
+	.walk		= nft_bitmap_walk,
+	.owner		= THIS_MODULE,
+};
+
+static int __init nft_bitmap_module_init(void)
+{
+	return nft_register_set(&nft_bitmap_ops);
+}
+
+static void __exit nft_bitmap_module_exit(void)
+{
+	nft_unregister_set(&nft_bitmap_ops);
+}
+
+module_init(nft_bitmap_module_init);
+module_exit(nft_bitmap_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
+MODULE_ALIAS_NFT_SET();