diff --git a/include/net/netfilter/nf_tables_core.h b/include/net/netfilter/nf_tables_core.h
index 7281895fa6d9..9759257ec8ec 100644
--- a/include/net/netfilter/nf_tables_core.h
+++ b/include/net/netfilter/nf_tables_core.h
@@ -74,6 +74,7 @@ extern struct nft_set_type nft_set_hash_type;
 extern struct nft_set_type nft_set_hash_fast_type;
 extern struct nft_set_type nft_set_rbtree_type;
 extern struct nft_set_type nft_set_bitmap_type;
+extern struct nft_set_type nft_set_pipapo_type;
 
 struct nft_expr;
 struct nft_regs;
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 5e9b2eb24349..3f572e5a975e 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -81,7 +81,8 @@ nf_tables-objs := nf_tables_core.o nf_tables_api.o nft_chain_filter.o \
 		  nft_chain_route.o nf_tables_offload.o
 
 nf_tables_set-objs := nf_tables_set_core.o \
-		      nft_set_hash.o nft_set_bitmap.o nft_set_rbtree.o
+		      nft_set_hash.o nft_set_bitmap.o nft_set_rbtree.o \
+		      nft_set_pipapo.o
 
 obj-$(CONFIG_NF_TABLES)		+= nf_tables.o
 obj-$(CONFIG_NF_TABLES_SET)	+= nf_tables_set.o
diff --git a/net/netfilter/nf_tables_set_core.c b/net/netfilter/nf_tables_set_core.c
index a9fce8d10051..586b621007eb 100644
--- a/net/netfilter/nf_tables_set_core.c
+++ b/net/netfilter/nf_tables_set_core.c
@@ -9,12 +9,14 @@ static int __init nf_tables_set_module_init(void)
 	nft_register_set(&nft_set_rhash_type);
 	nft_register_set(&nft_set_bitmap_type);
 	nft_register_set(&nft_set_rbtree_type);
+	nft_register_set(&nft_set_pipapo_type);
 
 	return 0;
 }
 
 static void __exit nf_tables_set_module_exit(void)
 {
+	nft_unregister_set(&nft_set_pipapo_type);
 	nft_unregister_set(&nft_set_rbtree_type);
 	nft_unregister_set(&nft_set_bitmap_type);
 	nft_unregister_set(&nft_set_rhash_type);
diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
new file mode 100644
index 000000000000..1829289a54f7
--- /dev/null
+++ b/net/netfilter/nft_set_pipapo.c
@@ -0,0 +1,2169 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/* PIPAPO: PIle PAcket POlicies: set for arbitrary concatenations of ranges
+ *
+ * Copyright (c) 2019 Red Hat GmbH
+ *
+ * Author: Stefano Brivio <sbrivio@redhat.com>
+ */
+
+/**
+ * DOC: Theory of Operation
+ *
+ *
+ * Problem
+ * -------
+ *
+ * Match packet bytes against entries composed of ranged or non-ranged packet
+ * field specifiers, mapping them to arbitrary references. For example:
+ *
+ * ::
+ *
+ *               --- fields --->
+ *      |    [net],[port],[net]... => [reference]
+ *   entries [net],[port],[net]... => [reference]
+ *      |    [net],[port],[net]... => [reference]
+ *      V    ...
+ *
+ * where [net] fields can be IP ranges or netmasks, and [port] fields are port
+ * ranges. Arbitrary packet fields can be matched.
+ *
+ *
+ * Algorithm Overview
+ * ------------------
+ *
+ * This algorithm is loosely inspired by [Ligatti 2010], and fundamentally
+ * relies on the consideration that every contiguous range in a space of b bits
+ * can be converted into b * 2 netmasks, from Theorem 3 in [Rottenstreich 2010],
+ * as also illustrated in Section 9 of [Kogan 2014].
+ *
+ * Classification against a number of entries, that require matching given bits
+ * of a packet field, is performed by grouping those bits in sets of arbitrary
+ * size, and classifying packet bits one group at a time.
+ *
+ * Example:
+ *   to match the source port (16 bits) of a packet, we can divide those 16 bits
+ *   in 4 groups of 4 bits each. Given the entry:
+ *      0000 0001 0101 1001
+ *   and a packet with source port:
+ *      0000 0001 1010 1001
+ *   first and second groups match, but the third doesn't. We conclude that the
+ *   packet doesn't match the given entry.
+ *
+ * Translate the set to a sequence of lookup tables, one per field. Each table
+ * has two dimensions: bit groups to be matched for a single packet field, and
+ * all the possible values of said groups (buckets). Input entries are
+ * represented as one or more rules, depending on the number of composing
+ * netmasks for the given field specifier, and a group match is indicated as a
+ * set bit, with number corresponding to the rule index, in all the buckets
+ * whose value matches the entry for a given group.
+ *
+ * Rules are mapped between fields through an array of x, n pairs, with each
+ * item mapping a matched rule to one or more rules. The position of the pair in
+ * the array indicates the matched rule to be mapped to the next field, x
+ * indicates the first rule index in the next field, and n the amount of
+ * next-field rules the current rule maps to.
+ *
+ * The mapping array for the last field maps to the desired references.
+ *
+ * To match, we perform table lookups using the values of grouped packet bits,
+ * and use a sequence of bitwise operations to progressively evaluate rule
+ * matching.
+ *
+ * A stand-alone, reference implementation, also including notes about possible
+ * future optimisations, is available at:
+ *    https://pipapo.lameexcu.se/
+ *
+ * Insertion
+ * ---------
+ *
+ * - For each packet field:
+ *
+ *   - divide the b packet bits we want to classify into groups of size t,
+ *     obtaining ceil(b / t) groups
+ *
+ *      Example: match on destination IP address, with t = 4: 32 bits, 8 groups
+ *      of 4 bits each
+ *
+ *   - allocate a lookup table with one column ("bucket") for each possible
+ *     value of a group, and with one row for each group
+ *
+ *      Example: 8 groups, 2^4 buckets:
+ *
+ * ::
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0
+ *        1
+ *        2
+ *        3
+ *        4
+ *        5
+ *        6
+ *        7
+ *
+ *   - map the bits we want to classify for the current field, for a given
+ *     entry, to a single rule for non-ranged and netmask set items, and to one
+ *     or multiple rules for ranges. Ranges are expanded to composing netmasks
+ *     by pipapo_expand().
+ *
+ *      Example: 2 entries, 10.0.0.5:1024 and 192.168.1.0-192.168.2.1:2048
+ *      - rule #0: 10.0.0.5
+ *      - rule #1: 192.168.1.0/24
+ *      - rule #2: 192.168.2.0/31
+ *
+ *   - insert references to the rules in the lookup table, selecting buckets
+ *     according to bit values of a rule in the given group. This is done by
+ *     pipapo_insert().
+ *
+ *      Example: given:
+ *      - rule #0: 10.0.0.5 mapping to buckets
+ *        < 0 10  0 0   0 0  0 5 >
+ *      - rule #1: 192.168.1.0/24 mapping to buckets
+ *        < 12 0  10 8  0 1  < 0..15 > < 0..15 > >
+ *      - rule #2: 192.168.2.0/31 mapping to buckets
+ *        < 12 0  10 8  0 2  0 < 0..1 > >
+ *
+ *      these bits are set in the lookup table:
+ *
+ * ::
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0    0                                              1,2
+ *        1   1,2                                      0
+ *        2    0                                      1,2
+ *        3    0                              1,2
+ *        4  0,1,2
+ *        5    0   1   2
+ *        6  0,1,2 1   1   1   1   1   1   1   1   1   1   1   1   1   1   1
+ *        7   1,2 1,2  1   1   1  0,1  1   1   1   1   1   1   1   1   1   1
+ *
+ *   - if this is not the last field in the set, fill a mapping array that maps
+ *     rules from the lookup table to rules belonging to the same entry in
+ *     the next lookup table, done by pipapo_map().
+ *
+ *     Note that as rules map to contiguous ranges of rules, given how netmask
+ *     expansion and insertion is performed, &union nft_pipapo_map_bucket stores
+ *     this information as pairs of first rule index, rule count.
+ *
+ *      Example: 2 entries, 10.0.0.5:1024 and 192.168.1.0-192.168.2.1:2048,
+ *      given lookup table #0 for field 0 (see example above):
+ *
+ * ::
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0    0                                              1,2
+ *        1   1,2                                      0
+ *        2    0                                      1,2
+ *        3    0                              1,2
+ *        4  0,1,2
+ *        5    0   1   2
+ *        6  0,1,2 1   1   1   1   1   1   1   1   1   1   1   1   1   1   1
+ *        7   1,2 1,2  1   1   1  0,1  1   1   1   1   1   1   1   1   1   1
+ *
+ *      and lookup table #1 for field 1 with:
+ *      - rule #0: 1024 mapping to buckets
+ *        < 0  0  4  0 >
+ *      - rule #1: 2048 mapping to buckets
+ *        < 0  0  5  0 >
+ *
+ * ::
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0   0,1
+ *        1   0,1
+ *        2                    0   1
+ *        3   0,1
+ *
+ *      we need to map rules for 10.0.0.5 in lookup table #0 (rule #0) to 1024
+ *      in lookup table #1 (rule #0) and rules for 192.168.1.0-192.168.2.1
+ *      (rules #1, #2) to 2048 in lookup table #2 (rule #1):
+ *
+ * ::
+ *
+ *       rule indices in current field: 0    1    2
+ *       map to rules in next field:    0    1    1
+ *
+ *   - if this is the last field in the set, fill a mapping array that maps
+ *     rules from the last lookup table to element pointers, also done by
+ *     pipapo_map().
+ *
+ *     Note that, in this implementation, we have two elements (start, end) for
+ *     each entry. The pointer to the end element is stored in this array, and
+ *     the pointer to the start element is linked from it.
+ *
+ *      Example: entry 10.0.0.5:1024 has a corresponding &struct nft_pipapo_elem
+ *      pointer, 0x66, and element for 192.168.1.0-192.168.2.1:2048 is at 0x42.
+ *      From the rules of lookup table #1 as mapped above:
+ *
+ * ::
+ *
+ *       rule indices in last field:    0    1
+ *       map to elements:             0x42  0x66
+ *
+ *
+ * Matching
+ * --------
+ *
+ * We use a result bitmap, with the size of a single lookup table bucket, to
+ * represent the matching state that applies at every algorithm step. This is
+ * done by pipapo_lookup().
+ *
+ * - For each packet field:
+ *
+ *   - start with an all-ones result bitmap (res_map in pipapo_lookup())
+ *
+ *   - perform a lookup into the table corresponding to the current field,
+ *     for each group, and at every group, AND the current result bitmap with
+ *     the value from the lookup table bucket
+ *
+ * ::
+ *
+ *      Example: 192.168.1.5 < 12 0  10 8  0 1  0 5 >, with lookup table from
+ *      insertion examples.
+ *      Lookup table buckets are at least 3 bits wide, we'll assume 8 bits for
+ *      convenience in this example. Initial result bitmap is 0xff, the steps
+ *      below show the value of the result bitmap after each group is processed:
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0    0                                              1,2
+ *        result bitmap is now: 0xff & 0x6 [bucket 12] = 0x6
+ *
+ *        1   1,2                                      0
+ *        result bitmap is now: 0x6 & 0x6 [bucket 0] = 0x6
+ *
+ *        2    0                                      1,2
+ *        result bitmap is now: 0x6 & 0x6 [bucket 10] = 0x6
+ *
+ *        3    0                              1,2
+ *        result bitmap is now: 0x6 & 0x6 [bucket 8] = 0x6
+ *
+ *        4  0,1,2
+ *        result bitmap is now: 0x6 & 0x7 [bucket 0] = 0x6
+ *
+ *        5    0   1   2
+ *        result bitmap is now: 0x6 & 0x2 [bucket 1] = 0x2
+ *
+ *        6  0,1,2 1   1   1   1   1   1   1   1   1   1   1   1   1   1   1
+ *        result bitmap is now: 0x2 & 0x7 [bucket 0] = 0x2
+ *
+ *        7   1,2 1,2  1   1   1  0,1  1   1   1   1   1   1   1   1   1   1
+ *        final result bitmap for this field is: 0x2 & 0x3 [bucket 5] = 0x2
+ *
+ *   - at the next field, start with a new, all-zeroes result bitmap. For each
+ *     bit set in the previous result bitmap, fill the new result bitmap
+ *     (fill_map in pipapo_lookup()) with the rule indices from the
+ *     corresponding buckets of the mapping field for this field, done by
+ *     pipapo_refill()
+ *
+ *      Example: with mapping table from insertion examples, with the current
+ *      result bitmap from the previous example, 0x02:
+ *
+ * ::
+ *
+ *       rule indices in current field: 0    1    2
+ *       map to rules in next field:    0    1    1
+ *
+ *      the new result bitmap will be 0x02: rule 1 was set, and rule 1 will be
+ *      set.
+ *
+ *      We can now extend this example to cover the second iteration of the step
+ *      above (lookup and AND bitmap): assuming the port field is
+ *      2048 < 0  0  5  0 >, with starting result bitmap 0x2, and lookup table
+ *      for "port" field from pre-computation example:
+ *
+ * ::
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0   0,1
+ *        1   0,1
+ *        2                    0   1
+ *        3   0,1
+ *
+ *       operations are: 0x2 & 0x3 [bucket 0] & 0x3 [bucket 0] & 0x2 [bucket 5]
+ *       & 0x3 [bucket 0], resulting bitmap is 0x2.
+ *
+ *   - if this is the last field in the set, look up the value from the mapping
+ *     array corresponding to the final result bitmap
+ *
+ *      Example: 0x2 resulting bitmap from 192.168.1.5:2048, mapping array for
+ *      last field from insertion example:
+ *
+ * ::
+ *
+ *       rule indices in last field:    0    1
+ *       map to elements:             0x42  0x66
+ *
+ *      the matching element is at 0x42.
+ *
+ *
+ * References
+ * ----------
+ *
+ * [Ligatti 2010]
+ *      A Packet-classification Algorithm for Arbitrary Bitmask Rules, with
+ *      Automatic Time-space Tradeoffs
+ *      Jay Ligatti, Josh Kuhn, and Chris Gage.
+ *      Proceedings of the IEEE International Conference on Computer
+ *      Communication Networks (ICCCN), August 2010.
+ *      http://www.cse.usf.edu/~ligatti/papers/grouper-conf.pdf
+ *
+ * [Rottenstreich 2010]
+ *      Worst-Case TCAM Rule Expansion
+ *      Ori Rottenstreich and Isaac Keslassy.
+ *      2010 Proceedings IEEE INFOCOM, San Diego, CA, 2010.
+ *      http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.212.4592&rep=rep1&type=pdf
+ *
+ * [Kogan 2014]
+ *      SAX-PAC (Scalable And eXpressive PAcket Classification)
+ *      Kirill Kogan, Sergey Nikolenko, Ori Rottenstreich, William Culhane,
+ *      and Patrick Eugster.
+ *      Proceedings of the 2014 ACM conference on SIGCOMM, August 2014.
+ *      http://www.sigcomm.org/sites/default/files/ccr/papers/2014/August/2619239-2626294.pdf
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables_core.h>
+#include <uapi/linux/netfilter/nf_tables.h>
+#include <net/ipv6.h>			/* For the maximum length of a field */
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
+
+/* Count of concatenated fields depends on count of 32-bit nftables registers */
+#define NFT_PIPAPO_MAX_FIELDS		NFT_REG32_COUNT
+
+/* Largest supported field size */
+#define NFT_PIPAPO_MAX_BYTES		(sizeof(struct in6_addr))
+#define NFT_PIPAPO_MAX_BITS		(NFT_PIPAPO_MAX_BYTES * BITS_PER_BYTE)
+
+/* Number of bits to be grouped together in lookup table buckets, arbitrary */
+#define NFT_PIPAPO_GROUP_BITS		4
+#define NFT_PIPAPO_GROUPS_PER_BYTE	(BITS_PER_BYTE / NFT_PIPAPO_GROUP_BITS)
+
+/* Fields are padded to 32 bits in input registers */
+#define NFT_PIPAPO_GROUPS_PADDED_SIZE(x)				\
+	(round_up((x) / NFT_PIPAPO_GROUPS_PER_BYTE, sizeof(u32)))
+#define NFT_PIPAPO_GROUPS_PADDING(x)					\
+	(NFT_PIPAPO_GROUPS_PADDED_SIZE((x)) - (x) / NFT_PIPAPO_GROUPS_PER_BYTE)
+
+/* Number of buckets, given by 2 ^ n, with n grouped bits */
+#define NFT_PIPAPO_BUCKETS		(1 << NFT_PIPAPO_GROUP_BITS)
+
+/* Each n-bit range maps to up to n * 2 rules */
+#define NFT_PIPAPO_MAP_NBITS		(const_ilog2(NFT_PIPAPO_MAX_BITS * 2))
+
+/* Use the rest of mapping table buckets for rule indices, but it makes no sense
+ * to exceed 32 bits
+ */
+#if BITS_PER_LONG == 64
+#define NFT_PIPAPO_MAP_TOBITS		32
+#else
+#define NFT_PIPAPO_MAP_TOBITS		(BITS_PER_LONG - NFT_PIPAPO_MAP_NBITS)
+#endif
+
+/* ...which gives us the highest allowed index for a rule */
+#define NFT_PIPAPO_RULE0_MAX		((1UL << (NFT_PIPAPO_MAP_TOBITS - 1)) \
+					- (1UL << NFT_PIPAPO_MAP_NBITS))
+
+#define nft_pipapo_for_each_field(field, index, match)		\
+	for ((field) = (match)->f, (index) = 0;			\
+	     (index) < (match)->field_count;			\
+	     (index)++, (field)++)
+
+/**
+ * union nft_pipapo_map_bucket - Bucket of mapping table
+ * @to:		First rule number (in next field) this rule maps to
+ * @n:		Number of rules (in next field) this rule maps to
+ * @e:		If there's no next field, pointer to element this rule maps to
+ */
+union nft_pipapo_map_bucket {
+	struct {
+#if BITS_PER_LONG == 64
+		static_assert(NFT_PIPAPO_MAP_TOBITS <= 32);
+		u32 to;
+
+		static_assert(NFT_PIPAPO_MAP_NBITS <= 32);
+		u32 n;
+#else
+		unsigned long to:NFT_PIPAPO_MAP_TOBITS;
+		unsigned long  n:NFT_PIPAPO_MAP_NBITS;
+#endif
+	};
+	struct nft_pipapo_elem *e;
+};
+
+/**
+ * struct nft_pipapo_field - Lookup, mapping tables and related data for a field
+ * @groups:	Amount of 4-bit groups
+ * @rules:	Number of inserted rules
+ * @bsize:	Size of each bucket in lookup table, in longs
+ * @lt:		Lookup table: 'groups' rows of NFT_PIPAPO_BUCKETS buckets
+ * @mt:		Mapping table: one bucket per rule
+ */
+struct nft_pipapo_field {
+	int groups;
+	unsigned long rules;
+	size_t bsize;
+	unsigned long *lt;
+	union nft_pipapo_map_bucket *mt;
+};
+
+/**
+ * struct nft_pipapo_match - Data used for lookup and matching
+ * @field_count		Amount of fields in set
+ * @scratch:		Preallocated per-CPU maps for partial matching results
+ * @bsize_max:		Maximum lookup table bucket size of all fields, in longs
+ * @rcu			Matching data is swapped on commits
+ * @f:			Fields, with lookup and mapping tables
+ */
+struct nft_pipapo_match {
+	int field_count;
+	unsigned long * __percpu *scratch;
+	size_t bsize_max;
+	struct rcu_head rcu;
+	struct nft_pipapo_field f[0];
+};
+
+/* Current working bitmap index, toggled between field matches */
+static DEFINE_PER_CPU(bool, nft_pipapo_scratch_index);
+
+/**
+ * struct nft_pipapo - Representation of a set
+ * @match:	Currently in-use matching data
+ * @clone:	Copy where pending insertions and deletions are kept
+ * @groups:	Total amount of 4-bit groups for fields in this set
+ * @width:	Total bytes to be matched for one packet, including padding
+ * @dirty:	Working copy has pending insertions or deletions
+ * @last_gc:	Timestamp of last garbage collection run, jiffies
+ * @start_data:	Key data of start element for insertion
+ * @start_elem:	Start element for insertion
+ *
+ * nft_pipapo_insert() is called separately with start and end elements to be
+ * inserted. While a tree implementation (see nft_set_rbtree) can insert nodes
+ * in the tree right away, we need to cache the start element, and perform the
+ * actual insertion once the end element is also seen. This is fine as insertion
+ * is serialised by the nftables API.
+ */
+struct nft_pipapo {
+	struct nft_pipapo_match __rcu *match;
+	struct nft_pipapo_match *clone;
+	int groups;
+	int width;
+	bool dirty;
+	unsigned long last_gc;
+	u8 start_data[NFT_DATA_VALUE_MAXLEN * sizeof(u32)];
+	struct nft_pipapo_elem *start_elem;
+};
+
+struct nft_pipapo_elem;
+
+/**
+ * struct nft_pipapo_elem - API-facing representation of single set element
+ * @start:	Pointer to element that represents start of interval
+ * @ext:	nftables API extensions
+ */
+struct nft_pipapo_elem {
+	struct nft_pipapo_elem *start;
+	struct nft_set_ext ext;
+};
+
+/**
+ * pipapo_refill() - For each set bit, set bits from selected mapping table item
+ * @map:	Bitmap to be scanned for set bits
+ * @len:	Length of bitmap in longs
+ * @rules:	Number of rules in field
+ * @dst:	Destination bitmap
+ * @mt:		Mapping table containing bit set specifiers
+ * @match_only:	Find a single bit and return, don't fill
+ *
+ * Iteration over set bits with __builtin_ctzl(): Daniel Lemire, public domain.
+ *
+ * For each bit set in map, select the bucket from mapping table with index
+ * corresponding to the position of the bit set. Use start bit and amount of
+ * bits specified in bucket to fill region in dst.
+ *
+ * Return: -1 on no match, bit position on 'match_only', 0 otherwise.
+ */
+static int pipapo_refill(unsigned long *map, int len, int rules,
+			 unsigned long *dst, union nft_pipapo_map_bucket *mt,
+			 bool match_only)
+{
+	unsigned long bitset;
+	int k, ret = -1;
+
+	for (k = 0; k < len; k++) {
+		bitset = map[k];
+		while (bitset) {
+			unsigned long t = bitset & -bitset;
+			int r = __builtin_ctzl(bitset);
+			int i = k * BITS_PER_LONG + r;
+
+			if (unlikely(i >= rules)) {
+				map[k] = 0;
+				return -1;
+			}
+
+			if (unlikely(match_only)) {
+				bitmap_clear(map, i, 1);
+				return i;
+			}
+
+			ret = 0;
+
+			bitmap_set(dst, mt[i].to, mt[i].n);
+
+			bitset ^= t;
+		}
+		map[k] = 0;
+	}
+
+	return ret;
+}
+
+/**
+ * nft_pipapo_lookup() - Lookup function
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @elem:	nftables API element representation containing key data
+ * @ext:	nftables API extension pointer, filled with matching reference
+ *
+ * For more details, see DOC: Theory of Operation.
+ *
+ * Return: true on match, false otherwise.
+ */
+static bool nft_pipapo_lookup(const struct net *net, const struct nft_set *set,
+			      const u32 *key, const struct nft_set_ext **ext)
+{
+	struct nft_pipapo *priv = nft_set_priv(set);
+	unsigned long *res_map, *fill_map;
+	u8 genmask = nft_genmask_cur(net);
+	const u8 *rp = (const u8 *)key;
+	struct nft_pipapo_match *m;
+	struct nft_pipapo_field *f;
+	bool map_index;
+	int i;
+
+	map_index = raw_cpu_read(nft_pipapo_scratch_index);
+
+	rcu_read_lock();
+	m = rcu_dereference(priv->match);
+
+	if (unlikely(!m || !*raw_cpu_ptr(m->scratch)))
+		goto out;
+
+	res_map  = *raw_cpu_ptr(m->scratch) + (map_index ? m->bsize_max : 0);
+	fill_map = *raw_cpu_ptr(m->scratch) + (map_index ? 0 : m->bsize_max);
+
+	memset(res_map, 0xff, m->bsize_max * sizeof(*res_map));
+
+	nft_pipapo_for_each_field(f, i, m) {
+		bool last = i == m->field_count - 1;
+		unsigned long *lt = f->lt;
+		int b, group;
+
+		/* For each 4-bit group: select lookup table bucket depending on
+		 * packet bytes value, then AND bucket value
+		 */
+		for (group = 0; group < f->groups; group++) {
+			u8 v;
+
+			if (group % 2) {
+				v = *rp & 0x0f;
+				rp++;
+			} else {
+				v = *rp >> 4;
+			}
+			__bitmap_and(res_map, res_map, lt + v * f->bsize,
+				     f->bsize * BITS_PER_LONG);
+
+			lt += f->bsize * NFT_PIPAPO_BUCKETS;
+		}
+
+		/* Now populate the bitmap for the next field, unless this is
+		 * the last field, in which case return the matched 'ext'
+		 * pointer if any.
+		 *
+		 * Now res_map contains the matching bitmap, and fill_map is the
+		 * bitmap for the next field.
+		 */
+next_match:
+		b = pipapo_refill(res_map, f->bsize, f->rules, fill_map, f->mt,
+				  last);
+		if (b < 0) {
+			rcu_read_unlock();
+			raw_cpu_write(nft_pipapo_scratch_index, map_index);
+
+			return false;
+		}
+
+		if (last) {
+			*ext = &f->mt[b].e->ext;
+			if (unlikely(nft_set_elem_expired(*ext) ||
+				     !nft_set_elem_active(*ext, genmask)))
+				goto next_match;
+
+			/* Last field: we're just returning the key without
+			 * filling the initial bitmap for the next field, so the
+			 * current inactive bitmap is clean and can be reused as
+			 * *next* bitmap (not initial) for the next packet.
+			 */
+			rcu_read_unlock();
+			raw_cpu_write(nft_pipapo_scratch_index, map_index);
+
+			return true;
+		}
+
+		/* Swap bitmap indices: res_map is the initial bitmap for the
+		 * next field, and fill_map is guaranteed to be all-zeroes at
+		 * this point.
+		 */
+		map_index = !map_index;
+		swap(res_map, fill_map);
+
+		rp += NFT_PIPAPO_GROUPS_PADDING(f->groups);
+	}
+
+out:
+	rcu_read_unlock();
+	return false;
+}
+
+/**
+ * pipapo_get() - Get matching start or end element reference given key data
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @data:	Key data to be matched against existing elements
+ * @flags:	If NFT_SET_ELEM_INTERVAL_END is passed, return the end element
+ *
+ * This is essentially the same as the lookup function, except that it matches
+ * key data against the uncommitted copy and doesn't use preallocated maps for
+ * bitmap results.
+ *
+ * Return: pointer to &struct nft_pipapo_elem on match, error pointer otherwise.
+ */
+static void *pipapo_get(const struct net *net, const struct nft_set *set,
+			const u8 *data, unsigned int flags)
+{
+	struct nft_pipapo *priv = nft_set_priv(set);
+	struct nft_pipapo_match *m = priv->clone;
+	unsigned long *res_map, *fill_map = NULL;
+	void *ret = ERR_PTR(-ENOENT);
+	struct nft_pipapo_field *f;
+	int i;
+
+	res_map = kmalloc_array(m->bsize_max, sizeof(*res_map), GFP_ATOMIC);
+	if (!res_map) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	fill_map = kcalloc(m->bsize_max, sizeof(*res_map), GFP_ATOMIC);
+	if (!fill_map) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	memset(res_map, 0xff, m->bsize_max * sizeof(*res_map));
+
+	nft_pipapo_for_each_field(f, i, m) {
+		bool last = i == m->field_count - 1;
+		unsigned long *lt = f->lt;
+		int b, group;
+
+		/* For each 4-bit group: select lookup table bucket depending on
+		 * packet bytes value, then AND bucket value
+		 */
+		for (group = 0; group < f->groups; group++) {
+			u8 v;
+
+			if (group % 2) {
+				v = *data & 0x0f;
+				data++;
+			} else {
+				v = *data >> 4;
+			}
+			__bitmap_and(res_map, res_map, lt + v * f->bsize,
+				     f->bsize * BITS_PER_LONG);
+
+			lt += f->bsize * NFT_PIPAPO_BUCKETS;
+		}
+
+		/* Now populate the bitmap for the next field, unless this is
+		 * the last field, in which case return the matched 'ext'
+		 * pointer if any.
+		 *
+		 * Now res_map contains the matching bitmap, and fill_map is the
+		 * bitmap for the next field.
+		 */
+next_match:
+		b = pipapo_refill(res_map, f->bsize, f->rules, fill_map, f->mt,
+				  last);
+		if (b < 0)
+			goto out;
+
+		if (last) {
+			if (nft_set_elem_expired(&f->mt[b].e->ext))
+				goto next_match;
+
+			if (flags & NFT_SET_ELEM_INTERVAL_END)
+				ret = f->mt[b].e;
+			else
+				ret = f->mt[b].e->start;
+			goto out;
+		}
+
+		data += NFT_PIPAPO_GROUPS_PADDING(f->groups);
+
+		/* Swap bitmap indices: fill_map will be the initial bitmap for
+		 * the next field (i.e. the new res_map), and res_map is
+		 * guaranteed to be all-zeroes at this point, ready to be filled
+		 * according to the next mapping table.
+		 */
+		swap(res_map, fill_map);
+	}
+
+out:
+	kfree(fill_map);
+	kfree(res_map);
+	return ret;
+}
+
+/**
+ * nft_pipapo_get() - Get matching element reference given key data
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @elem:	nftables API element representation containing key data
+ * @flags:	If NFT_SET_ELEM_INTERVAL_END is passed, return the end element
+ */
+static void *nft_pipapo_get(const struct net *net, const struct nft_set *set,
+			    const struct nft_set_elem *elem, unsigned int flags)
+{
+	return pipapo_get(net, set, (const u8 *)elem->key.val.data, flags);
+}
+
+/**
+ * pipapo_resize() - Resize lookup or mapping table, or both
+ * @f:		Field containing lookup and mapping tables
+ * @old_rules:	Previous amount of rules in field
+ * @rules:	New amount of rules
+ *
+ * Increase, decrease or maintain tables size depending on new amount of rules,
+ * and copy data over. In case the new size is smaller, throw away data for
+ * highest-numbered rules.
+ *
+ * Return: 0 on success, -ENOMEM on allocation failure.
+ */
+static int pipapo_resize(struct nft_pipapo_field *f, int old_rules, int rules)
+{
+	long *new_lt = NULL, *new_p, *old_lt = f->lt, *old_p;
+	union nft_pipapo_map_bucket *new_mt, *old_mt = f->mt;
+	size_t new_bucket_size, copy;
+	int group, bucket;
+
+	new_bucket_size = DIV_ROUND_UP(rules, BITS_PER_LONG);
+
+	if (new_bucket_size == f->bsize)
+		goto mt;
+
+	if (new_bucket_size > f->bsize)
+		copy = f->bsize;
+	else
+		copy = new_bucket_size;
+
+	new_lt = kvzalloc(f->groups * NFT_PIPAPO_BUCKETS * new_bucket_size *
+			  sizeof(*new_lt), GFP_KERNEL);
+	if (!new_lt)
+		return -ENOMEM;
+
+	new_p = new_lt;
+	old_p = old_lt;
+	for (group = 0; group < f->groups; group++) {
+		for (bucket = 0; bucket < NFT_PIPAPO_BUCKETS; bucket++) {
+			memcpy(new_p, old_p, copy * sizeof(*new_p));
+			new_p += copy;
+			old_p += copy;
+
+			if (new_bucket_size > f->bsize)
+				new_p += new_bucket_size - f->bsize;
+			else
+				old_p += f->bsize - new_bucket_size;
+		}
+	}
+
+mt:
+	new_mt = kvmalloc(rules * sizeof(*new_mt), GFP_KERNEL);
+	if (!new_mt) {
+		kvfree(new_lt);
+		return -ENOMEM;
+	}
+
+	memcpy(new_mt, f->mt, min(old_rules, rules) * sizeof(*new_mt));
+	if (rules > old_rules) {
+		memset(new_mt + old_rules, 0,
+		       (rules - old_rules) * sizeof(*new_mt));
+	}
+
+	if (new_lt) {
+		f->bsize = new_bucket_size;
+		f->lt = new_lt;
+		kvfree(old_lt);
+	}
+
+	f->mt = new_mt;
+	kvfree(old_mt);
+
+	return 0;
+}
+
+/**
+ * pipapo_bucket_set() - Set rule bit in bucket given group and group value
+ * @f:		Field containing lookup table
+ * @rule:	Rule index
+ * @group:	Group index
+ * @v:		Value of bit group
+ */
+static void pipapo_bucket_set(struct nft_pipapo_field *f, int rule, int group,
+			      int v)
+{
+	unsigned long *pos;
+
+	pos = f->lt + f->bsize * NFT_PIPAPO_BUCKETS * group;
+	pos += f->bsize * v;
+
+	__set_bit(rule, pos);
+}
+
+/**
+ * pipapo_insert() - Insert new rule in field given input key and mask length
+ * @f:		Field containing lookup table
+ * @k:		Input key for classification, without nftables padding
+ * @mask_bits:	Length of mask; matches field length for non-ranged entry
+ *
+ * Insert a new rule reference in lookup buckets corresponding to k and
+ * mask_bits.
+ *
+ * Return: 1 on success (one rule inserted), negative error code on failure.
+ */
+static int pipapo_insert(struct nft_pipapo_field *f, const uint8_t *k,
+			 int mask_bits)
+{
+	int rule = f->rules++, group, ret;
+
+	ret = pipapo_resize(f, f->rules - 1, f->rules);
+	if (ret)
+		return ret;
+
+	for (group = 0; group < f->groups; group++) {
+		int i, v;
+		u8 mask;
+
+		if (group % 2)
+			v = k[group / 2] & 0x0f;
+		else
+			v = k[group / 2] >> 4;
+
+		if (mask_bits >= (group + 1) * 4) {
+			/* Not masked */
+			pipapo_bucket_set(f, rule, group, v);
+		} else if (mask_bits <= group * 4) {
+			/* Completely masked */
+			for (i = 0; i < NFT_PIPAPO_BUCKETS; i++)
+				pipapo_bucket_set(f, rule, group, i);
+		} else {
+			/* The mask limit falls on this group */
+			mask = 0x0f >> (mask_bits - group * 4);
+			for (i = 0; i < NFT_PIPAPO_BUCKETS; i++) {
+				if ((i & ~mask) == (v & ~mask))
+					pipapo_bucket_set(f, rule, group, i);
+			}
+		}
+	}
+
+	return 1;
+}
+
+/**
+ * pipapo_step_diff() - Check if setting @step bit in netmask would change it
+ * @base:	Mask we are expanding
+ * @step:	Step bit for given expansion step
+ * @len:	Total length of mask space (set and unset bits), bytes
+ *
+ * Convenience function for mask expansion.
+ *
+ * Return: true if step bit changes mask (i.e. isn't set), false otherwise.
+ */
+static bool pipapo_step_diff(u8 *base, int step, int len)
+{
+	/* Network order, byte-addressed */
+#ifdef __BIG_ENDIAN__
+	return !(BIT(step % BITS_PER_BYTE) & base[step / BITS_PER_BYTE]);
+#else
+	return !(BIT(step % BITS_PER_BYTE) &
+		 base[len - 1 - step / BITS_PER_BYTE]);
+#endif
+}
+
+/**
+ * pipapo_step_after_end() - Check if mask exceeds range end with given step
+ * @base:	Mask we are expanding
+ * @end:	End of range
+ * @step:	Step bit for given expansion step, highest bit to be set
+ * @len:	Total length of mask space (set and unset bits), bytes
+ *
+ * Convenience function for mask expansion.
+ *
+ * Return: true if mask exceeds range setting step bits, false otherwise.
+ */
+static bool pipapo_step_after_end(const u8 *base, const u8 *end, int step,
+				  int len)
+{
+	u8 tmp[NFT_PIPAPO_MAX_BYTES];
+	int i;
+
+	memcpy(tmp, base, len);
+
+	/* Network order, byte-addressed */
+	for (i = 0; i <= step; i++)
+#ifdef __BIG_ENDIAN__
+		tmp[i / BITS_PER_BYTE] |= BIT(i % BITS_PER_BYTE);
+#else
+		tmp[len - 1 - i / BITS_PER_BYTE] |= BIT(i % BITS_PER_BYTE);
+#endif
+
+	return memcmp(tmp, end, len) > 0;
+}
+
+/**
+ * pipapo_base_sum() - Sum step bit to given len-sized netmask base with carry
+ * @base:	Netmask base
+ * @step:	Step bit to sum
+ * @len:	Netmask length, bytes
+ */
+static void pipapo_base_sum(u8 *base, int step, int len)
+{
+	bool carry = false;
+	int i;
+
+	/* Network order, byte-addressed */
+#ifdef __BIG_ENDIAN__
+	for (i = step / BITS_PER_BYTE; i < len; i++) {
+#else
+	for (i = len - 1 - step / BITS_PER_BYTE; i >= 0; i--) {
+#endif
+		if (carry)
+			base[i]++;
+		else
+			base[i] += 1 << (step % BITS_PER_BYTE);
+
+		if (base[i])
+			break;
+
+		carry = true;
+	}
+}
+
+/**
+ * expand() - Expand range to composing netmasks and insert into lookup table
+ * @f:		Field containing lookup table
+ * @start:	Start of range
+ * @end:	End of range
+ * @len:	Length of value in bits
+ *
+ * Expand range to composing netmasks and insert corresponding rule references
+ * in lookup buckets.
+ *
+ * Return: number of inserted rules on success, negative error code on failure.
+ */
+static int pipapo_expand(struct nft_pipapo_field *f,
+			 const u8 *start, const u8 *end, int len)
+{
+	int step, masks = 0, bytes = DIV_ROUND_UP(len, BITS_PER_BYTE);
+	u8 base[NFT_PIPAPO_MAX_BYTES];
+
+	memcpy(base, start, bytes);
+	while (memcmp(base, end, bytes) <= 0) {
+		int err;
+
+		step = 0;
+		while (pipapo_step_diff(base, step, bytes)) {
+			if (pipapo_step_after_end(base, end, step, bytes))
+				break;
+
+			step++;
+			if (step >= len) {
+				if (!masks) {
+					pipapo_insert(f, base, 0);
+					masks = 1;
+				}
+				goto out;
+			}
+		}
+
+		err = pipapo_insert(f, base, len - step);
+
+		if (err < 0)
+			return err;
+
+		masks++;
+		pipapo_base_sum(base, step, bytes);
+	}
+out:
+	return masks;
+}
+
+/**
+ * pipapo_map() - Insert rules in mapping tables, mapping them between fields
+ * @m:		Matching data, including mapping table
+ * @map:	Table of rule maps: array of first rule and amount of rules
+ *		in next field a given rule maps to, for each field
+ * @ext:	For last field, nft_set_ext pointer matching rules map to
+ */
+static void pipapo_map(struct nft_pipapo_match *m,
+		       union nft_pipapo_map_bucket map[NFT_PIPAPO_MAX_FIELDS],
+		       struct nft_pipapo_elem *e)
+{
+	struct nft_pipapo_field *f;
+	int i, j;
+
+	for (i = 0, f = m->f; i < m->field_count - 1; i++, f++) {
+		for (j = 0; j < map[i].n; j++) {
+			f->mt[map[i].to + j].to = map[i + 1].to;
+			f->mt[map[i].to + j].n = map[i + 1].n;
+		}
+	}
+
+	/* Last field: map to ext instead of mapping to next field */
+	for (j = 0; j < map[i].n; j++)
+		f->mt[map[i].to + j].e = e;
+}
+
+/**
+ * pipapo_realloc_scratch() - Reallocate scratch maps for partial match results
+ * @m:		Matching data
+ * @bsize_max	Maximum bucket size, scratch maps cover two buckets
+ *
+ * Return: 0 on success, -ENOMEM on failure.
+ */
+static int pipapo_realloc_scratch(struct nft_pipapo_match *m,
+				  unsigned long bsize_max)
+{
+	int i;
+
+	for_each_possible_cpu(i) {
+		unsigned long *scratch;
+
+		scratch = kzalloc_node(bsize_max * sizeof(*scratch) * 2,
+				       GFP_KERNEL, cpu_to_node(i));
+		if (!scratch)
+			return -ENOMEM;
+
+		kfree(*per_cpu_ptr(m->scratch, i));
+
+		*per_cpu_ptr(m->scratch, i) = scratch;
+	}
+
+	return 0;
+}
+
+/**
+ * nft_pipapo_insert() - Validate and insert ranged elements
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @elem:	nftables API element representation containing key data
+ * @flags:	If NFT_SET_ELEM_INTERVAL_END is passed, this is the end element
+ * @ext2:	Filled with pointer to &struct nft_set_ext in inserted element
+ *
+ * In this set implementation, this functions needs to be called twice, with
+ * start and end element, to obtain a valid entry insertion. Calls to this
+ * function are serialised, so we can store element and key data on the first
+ * call with start element, and use it on the second call once we get the end
+ * element too.
+ *
+ * Return: 0 on success, error pointer on failure.
+ */
+static int nft_pipapo_insert(const struct net *net, const struct nft_set *set,
+			     const struct nft_set_elem *elem,
+			     struct nft_set_ext **ext2)
+{
+	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
+	const u8 *data = (const u8 *)elem->key.val.data, *start, *end;
+	union nft_pipapo_map_bucket rulemap[NFT_PIPAPO_MAX_FIELDS];
+	struct nft_pipapo *priv = nft_set_priv(set);
+	struct nft_pipapo_match *m = priv->clone;
+	struct nft_pipapo_elem *e = elem->priv;
+	struct nft_pipapo_field *f;
+	int i, bsize_max, err = 0;
+	void *dup;
+
+	dup = nft_pipapo_get(net, set, elem, 0);
+	if (PTR_ERR(dup) != -ENOENT) {
+		if (IS_ERR(dup))
+			return PTR_ERR(dup);
+		*ext2 = dup;
+		return -EEXIST;
+	}
+
+	if (!nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) ||
+	    !(*nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)) {
+		priv->start_elem = e;
+		*ext2 = &e->ext;
+		memcpy(priv->start_data, data, priv->width);
+		return 0;
+	}
+
+	e->start = priv->start_elem;
+
+	/* Validate */
+	start = priv->start_data;
+	end = data;
+
+	nft_pipapo_for_each_field(f, i, m) {
+		if (f->rules >= (unsigned long)NFT_PIPAPO_RULE0_MAX)
+			return -ENOSPC;
+
+		if (memcmp(start, end,
+			   f->groups / NFT_PIPAPO_GROUPS_PER_BYTE) > 0)
+			return -EINVAL;
+
+		start += NFT_PIPAPO_GROUPS_PADDED_SIZE(f->groups);
+		end += NFT_PIPAPO_GROUPS_PADDED_SIZE(f->groups);
+	}
+
+	/* Insert */
+	priv->dirty = true;
+
+	bsize_max = m->bsize_max;
+
+	start = priv->start_data;
+	end = data;
+	nft_pipapo_for_each_field(f, i, m) {
+		int ret;
+
+		rulemap[i].to = f->rules;
+
+		ret = memcmp(start, end,
+			     f->groups / NFT_PIPAPO_GROUPS_PER_BYTE);
+		if (!ret) {
+			ret = pipapo_insert(f, start,
+					    f->groups * NFT_PIPAPO_GROUP_BITS);
+		} else {
+			ret = pipapo_expand(f, start, end,
+					    f->groups * NFT_PIPAPO_GROUP_BITS);
+		}
+
+		if (f->bsize > bsize_max)
+			bsize_max = f->bsize;
+
+		rulemap[i].n = ret;
+
+		start += NFT_PIPAPO_GROUPS_PADDED_SIZE(f->groups);
+		end += NFT_PIPAPO_GROUPS_PADDED_SIZE(f->groups);
+	}
+
+	if (!*this_cpu_ptr(m->scratch) || bsize_max > m->bsize_max) {
+		err = pipapo_realloc_scratch(m, bsize_max);
+		if (err)
+			return err;
+
+		this_cpu_write(nft_pipapo_scratch_index, false);
+
+		m->bsize_max = bsize_max;
+	}
+
+	*ext2 = &e->ext;
+
+	pipapo_map(m, rulemap, e);
+
+	return 0;
+}
+
+/**
+ * pipapo_clone() - Clone matching data to create new working copy
+ * @old:	Existing matching data
+ *
+ * Return: copy of matching data passed as 'old', error pointer on failure
+ */
+static struct nft_pipapo_match *pipapo_clone(struct nft_pipapo_match *old)
+{
+	struct nft_pipapo_field *dst, *src;
+	struct nft_pipapo_match *new;
+	int i;
+
+	new = kmalloc(sizeof(*new) + sizeof(*dst) * old->field_count,
+		      GFP_KERNEL);
+	if (!new)
+		return ERR_PTR(-ENOMEM);
+
+	new->field_count = old->field_count;
+	new->bsize_max = old->bsize_max;
+
+	new->scratch = alloc_percpu(*new->scratch);
+	if (!new->scratch)
+		goto out_scratch;
+
+	rcu_head_init(&new->rcu);
+
+	src = old->f;
+	dst = new->f;
+
+	for (i = 0; i < old->field_count; i++) {
+		memcpy(dst, src, offsetof(struct nft_pipapo_field, lt));
+
+		dst->lt = kvzalloc(src->groups * NFT_PIPAPO_BUCKETS *
+				   src->bsize * sizeof(*dst->lt),
+				   GFP_KERNEL);
+		if (!dst->lt)
+			goto out_lt;
+
+		memcpy(dst->lt, src->lt,
+		       src->bsize * sizeof(*dst->lt) *
+		       src->groups * NFT_PIPAPO_BUCKETS);
+
+		dst->mt = kvmalloc(src->rules * sizeof(*src->mt), GFP_KERNEL);
+		if (!dst->mt)
+			goto out_mt;
+
+		memcpy(dst->mt, src->mt, src->rules * sizeof(*src->mt));
+		src++;
+		dst++;
+	}
+
+	return new;
+
+out_mt:
+	kvfree(dst->lt);
+out_lt:
+	for (dst--; i > 0; i--) {
+		kvfree(dst->mt);
+		kvfree(dst->lt);
+		dst--;
+	}
+	free_percpu(new->scratch);
+out_scratch:
+	kfree(new);
+
+	return ERR_PTR(-ENOMEM);
+}
+
+/**
+ * pipapo_rules_same_key() - Get number of rules originated from the same entry
+ * @f:		Field containing mapping table
+ * @first:	Index of first rule in set of rules mapping to same entry
+ *
+ * Using the fact that all rules in a field that originated from the same entry
+ * will map to the same set of rules in the next field, or to the same element
+ * reference, return the cardinality of the set of rules that originated from
+ * the same entry as the rule with index @first, @first rule included.
+ *
+ * In pictures:
+ *				rules
+ *	field #0		0    1    2    3    4
+ *		map to:		0    1   2-4  2-4  5-9
+ *				.    .    .......   . ...
+ *				|    |    |    | \   \
+ *				|    |    |    |  \   \
+ *				|    |    |    |   \   \
+ *				'    '    '    '    '   \
+ *	in field #1		0    1    2    3    4    5 ...
+ *
+ * if this is called for rule 2 on field #0, it will return 3, as also rules 2
+ * and 3 in field 0 map to the same set of rules (2, 3, 4) in the next field.
+ *
+ * For the last field in a set, we can rely on associated entries to map to the
+ * same element references.
+ *
+ * Return: Number of rules that originated from the same entry as @first.
+ */
+static int pipapo_rules_same_key(struct nft_pipapo_field *f, int first)
+{
+	struct nft_pipapo_elem *e = NULL; /* Keep gcc happy */
+	int r;
+
+	for (r = first; r < f->rules; r++) {
+		if (r != first && e != f->mt[r].e)
+			return r - first;
+
+		e = f->mt[r].e;
+	}
+
+	if (r != first)
+		return r - first;
+
+	return 0;
+}
+
+/**
+ * pipapo_unmap() - Remove rules from mapping tables, renumber remaining ones
+ * @mt:		Mapping array
+ * @rules:	Original amount of rules in mapping table
+ * @start:	First rule index to be removed
+ * @n:		Amount of rules to be removed
+ * @to_offset:	First rule index, in next field, this group of rules maps to
+ * @is_last:	If this is the last field, delete reference from mapping array
+ *
+ * This is used to unmap rules from the mapping table for a single field,
+ * maintaining consistency and compactness for the existing ones.
+ *
+ * In pictures: let's assume that we want to delete rules 2 and 3 from the
+ * following mapping array:
+ *
+ *                 rules
+ *               0      1      2      3      4
+ *      map to:  4-10   4-10   11-15  11-15  16-18
+ *
+ * the result will be:
+ *
+ *                 rules
+ *               0      1      2
+ *      map to:  4-10   4-10   11-13
+ *
+ * for fields before the last one. In case this is the mapping table for the
+ * last field in a set, and rules map to pointers to &struct nft_pipapo_elem:
+ *
+ *                      rules
+ *                        0      1      2      3      4
+ *  element pointers:  0x42   0x42   0x33   0x33   0x44
+ *
+ * the result will be:
+ *
+ *                      rules
+ *                        0      1      2
+ *  element pointers:  0x42   0x42   0x44
+ */
+static void pipapo_unmap(union nft_pipapo_map_bucket *mt, int rules,
+			 int start, int n, int to_offset, bool is_last)
+{
+	int i;
+
+	memmove(mt + start, mt + start + n, (rules - start - n) * sizeof(*mt));
+	memset(mt + rules - n, 0, n * sizeof(*mt));
+
+	if (is_last)
+		return;
+
+	for (i = start; i < rules - n; i++)
+		mt[i].to -= to_offset;
+}
+
+/**
+ * pipapo_drop() - Delete entry from lookup and mapping tables, given rule map
+ * @m:		Matching data
+ * @rulemap	Table of rule maps, arrays of first rule and amount of rules
+ *		in next field a given entry maps to, for each field
+ *
+ * For each rule in lookup table buckets mapping to this set of rules, drop
+ * all bits set in lookup table mapping. In pictures, assuming we want to drop
+ * rules 0 and 1 from this lookup table:
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0    0                                              1,2
+ *        1   1,2                                      0
+ *        2    0                                      1,2
+ *        3    0                              1,2
+ *        4  0,1,2
+ *        5    0   1   2
+ *        6  0,1,2 1   1   1   1   1   1   1   1   1   1   1   1   1   1   1
+ *        7   1,2 1,2  1   1   1  0,1  1   1   1   1   1   1   1   1   1   1
+ *
+ * rule 2 becomes rule 0, and the result will be:
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0                                                    0
+ *        1    0
+ *        2                                            0
+ *        3                                    0
+ *        4    0
+ *        5            0
+ *        6    0
+ *        7    0   0
+ *
+ * once this is done, call unmap() to drop all the corresponding rule references
+ * from mapping tables.
+ */
+static void pipapo_drop(struct nft_pipapo_match *m,
+			union nft_pipapo_map_bucket rulemap[])
+{
+	struct nft_pipapo_field *f;
+	int i;
+
+	nft_pipapo_for_each_field(f, i, m) {
+		int g;
+
+		for (g = 0; g < f->groups; g++) {
+			unsigned long *pos;
+			int b;
+
+			pos = f->lt + g * NFT_PIPAPO_BUCKETS * f->bsize;
+
+			for (b = 0; b < NFT_PIPAPO_BUCKETS; b++) {
+				bitmap_cut(pos, pos, rulemap[i].to,
+					   rulemap[i].n,
+					   f->bsize * BITS_PER_LONG);
+
+				pos += f->bsize;
+			}
+		}
+
+		pipapo_unmap(f->mt, f->rules, rulemap[i].to, rulemap[i].n,
+			     rulemap[i + 1].n, i == m->field_count - 1);
+		if (pipapo_resize(f, f->rules, f->rules - rulemap[i].n)) {
+			/* We can ignore this, a failure to shrink tables down
+			 * doesn't make tables invalid.
+			 */
+			;
+		}
+		f->rules -= rulemap[i].n;
+	}
+}
+
+/**
+ * pipapo_gc() - Drop expired entries from set, destroy start and end elements
+ * @set:	nftables API set representation
+ * @m:		Matching data
+ */
+static void pipapo_gc(const struct nft_set *set, struct nft_pipapo_match *m)
+{
+	struct nft_pipapo *priv = nft_set_priv(set);
+	int rules_f0, first_rule = 0;
+
+	while ((rules_f0 = pipapo_rules_same_key(m->f, first_rule))) {
+		union nft_pipapo_map_bucket rulemap[NFT_PIPAPO_MAX_FIELDS];
+		struct nft_pipapo_field *f;
+		struct nft_pipapo_elem *e;
+		int i, start, rules_fx;
+
+		start = first_rule;
+		rules_fx = rules_f0;
+
+		nft_pipapo_for_each_field(f, i, m) {
+			rulemap[i].to = start;
+			rulemap[i].n = rules_fx;
+
+			if (i < m->field_count - 1) {
+				rules_fx = f->mt[start].n;
+				start = f->mt[start].to;
+			}
+		}
+
+		/* Pick the last field, and its last index */
+		f--;
+		i--;
+		e = f->mt[rulemap[i].to].e;
+		if (nft_set_elem_expired(&e->ext) &&
+		    !nft_set_elem_mark_busy(&e->ext)) {
+			priv->dirty = true;
+			pipapo_drop(m, rulemap);
+
+			rcu_barrier();
+			nft_set_elem_destroy(set, e->start, true);
+			nft_set_elem_destroy(set, e, true);
+
+			/* And check again current first rule, which is now the
+			 * first we haven't checked.
+			 */
+		} else {
+			first_rule += rules_f0;
+		}
+	}
+
+	priv->last_gc = jiffies;
+}
+
+/**
+ * pipapo_free_fields() - Free per-field tables contained in matching data
+ * @m:		Matching data
+ */
+static void pipapo_free_fields(struct nft_pipapo_match *m)
+{
+	struct nft_pipapo_field *f;
+	int i;
+
+	nft_pipapo_for_each_field(f, i, m) {
+		kvfree(f->lt);
+		kvfree(f->mt);
+	}
+}
+
+/**
+ * pipapo_reclaim_match - RCU callback to free fields from old matching data
+ * @rcu:	RCU head
+ */
+static void pipapo_reclaim_match(struct rcu_head *rcu)
+{
+	struct nft_pipapo_match *m;
+	int i;
+
+	m = container_of(rcu, struct nft_pipapo_match, rcu);
+
+	for_each_possible_cpu(i)
+		kfree(*per_cpu_ptr(m->scratch, i));
+
+	free_percpu(m->scratch);
+
+	pipapo_free_fields(m);
+
+	kfree(m);
+}
+
+/**
+ * pipapo_commit() - Replace lookup data with current working copy
+ * @set:	nftables API set representation
+ *
+ * While at it, check if we should perform garbage collection on the working
+ * copy before committing it for lookup, and don't replace the table if the
+ * working copy doesn't have pending changes.
+ *
+ * We also need to create a new working copy for subsequent insertions and
+ * deletions.
+ */
+static void pipapo_commit(const struct nft_set *set)
+{
+	struct nft_pipapo *priv = nft_set_priv(set);
+	struct nft_pipapo_match *new_clone, *old;
+
+	if (time_after_eq(jiffies, priv->last_gc + nft_set_gc_interval(set)))
+		pipapo_gc(set, priv->clone);
+
+	if (!priv->dirty)
+		return;
+
+	new_clone = pipapo_clone(priv->clone);
+	if (IS_ERR(new_clone))
+		return;
+
+	priv->dirty = false;
+
+	old = rcu_access_pointer(priv->match);
+	rcu_assign_pointer(priv->match, priv->clone);
+	if (old)
+		call_rcu(&old->rcu, pipapo_reclaim_match);
+
+	priv->clone = new_clone;
+}
+
+/**
+ * nft_pipapo_activate() - Mark element reference as active given key, commit
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @elem:	nftables API element representation containing key data
+ *
+ * On insertion, elements are added to a copy of the matching data currently
+ * in use for lookups, and not directly inserted into current lookup data, so
+ * we'll take care of that by calling pipapo_commit() here. This is probably as
+ * close as we can get to an actual atomic transaction: both nft_pipapo_insert()
+ * and nft_pipapo_activate() are called once for each element, hence we can't
+ * purpose either one as a real commit operation.
+ */
+static void nft_pipapo_activate(const struct net *net,
+				const struct nft_set *set,
+				const struct nft_set_elem *elem)
+{
+	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
+	struct nft_pipapo_elem *e;
+
+	if (!nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) ||
+	    !(*nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)) {
+		e = pipapo_get(net, set, (const u8 *)elem->key.val.data, 0);
+		if (IS_ERR(e))
+			return;
+
+		nft_set_elem_change_active(net, set, &e->ext);
+		nft_set_elem_clear_busy(&e->ext);
+
+		return;
+	}
+
+	e = pipapo_get(net, set, (const u8 *)elem->key.val.data,
+		       NFT_SET_ELEM_INTERVAL_END);
+	if (IS_ERR(e))
+		return;
+
+	nft_set_elem_change_active(net, set, &e->ext);
+	nft_set_elem_clear_busy(&e->ext);
+
+	pipapo_commit(set);
+}
+
+/**
+ * pipapo_deactivate() - Check that element is in set, mark as inactive
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @data:	Input key data
+ * @ext:	nftables API extension pointer, used to check for end element
+ *
+ * This is a convenience function that can be called from both
+ * nft_pipapo_deactivate() and nft_pipapo_flush(), as they are in fact the same
+ * operation.
+ *
+ * Return: deactivated element if found, NULL otherwise.
+ */
+static void *pipapo_deactivate(const struct net *net, const struct nft_set *set,
+			       const u8 *data, const struct nft_set_ext *ext)
+{
+	u8 genmask = nft_genmask_next(net);
+	struct nft_pipapo_elem *e;
+	unsigned int flags = 0;
+
+	if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS))
+		flags = *nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END;
+
+	e = pipapo_get(net, set, data, flags);
+	if (IS_ERR(e))
+		return NULL;
+
+	if (nft_set_elem_active(&e->ext, genmask))
+		nft_set_elem_change_active(net, set, &e->ext);
+
+	return e;
+}
+
+/**
+ * nft_pipapo_deactivate() - Call pipapo_deactivate() to make element inactive
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @elem:	nftables API element representation containing key data
+ *
+ * Return: deactivated element if found, NULL otherwise.
+ */
+static void *nft_pipapo_deactivate(const struct net *net,
+				   const struct nft_set *set,
+				   const struct nft_set_elem *elem)
+{
+	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
+
+	return pipapo_deactivate(net, set, (const u8 *)elem->key.val.data, ext);
+}
+
+/**
+ * nft_pipapo_flush() - Call pipapo_deactivate() to make element inactive
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @elem:	nftables API element representation containing key data
+ *
+ * This is functionally the same as nft_pipapo_deactivate(), with a slightly
+ * different interface, and it's also called once for each element in a set
+ * being flushed, so we can't implement an atomic flush operation, which would
+ * otherwise be as simple as allocating an empty copy of the matching data.
+ *
+ * Note that we could in theory do that, mark the set as flushed, and ignore
+ * subsequent calls, but we would leak all the elements after the first one,
+ * because they wouldn't then be freed as result of API calls.
+ *
+ * Return: true if element was found and deactivated.
+ */
+static bool nft_pipapo_flush(const struct net *net, const struct nft_set *set,
+			     void *elem)
+{
+	struct nft_pipapo_elem *e = elem;
+
+	return pipapo_deactivate(net, set, (const u8 *)nft_set_ext_key(&e->ext),
+				 &e->ext);
+}
+
+/**
+ * pipapo_get_boundaries() - Get byte interval for associated rules
+ * @f:		Field including lookup table
+ * @first_rule:	First rule (lowest index)
+ * @rule_count:	Number of associated rules
+ * @left:	Byte expression for left boundary (start of range)
+ * @right:	Byte expression for right boundary (end of range)
+ *
+ * Given the first rule and amount of rules that originated from the same entry,
+ * build the original range associated with the entry, and calculate the length
+ * of the originating netmask.
+ *
+ * In pictures:
+ *
+ *                     bucket
+ *      group  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
+ *        0                                                   1,2
+ *        1   1,2
+ *        2                                           1,2
+ *        3                                   1,2
+ *        4   1,2
+ *        5        1   2
+ *        6   1,2  1   1   1   1   1   1   1   1   1   1   1   1   1   1   1
+ *        7   1,2 1,2  1   1   1   1   1   1   1   1   1   1   1   1   1   1
+ *
+ * this is the lookup table corresponding to the IPv4 range
+ * 192.168.1.0-192.168.2.1, which was expanded to the two composing netmasks,
+ * rule #1: 192.168.1.0/24, and rule #2: 192.168.2.0/31.
+ *
+ * This function fills @left and @right with the byte values of the leftmost
+ * and rightmost bucket indices for the lowest and highest rule indices,
+ * respectively. If @first_rule is 1 and @rule_count is 2, we obtain, in
+ * nibbles:
+ *   left:  < 12, 0, 10, 8, 0, 1, 0, 0 >
+ *   right: < 12, 0, 10, 8, 0, 2, 2, 1 >
+ * corresponding to bytes:
+ *   left:  < 192, 168, 1, 0 >
+ *   right: < 192, 168, 2, 1 >
+ * with mask length irrelevant here, unused on return, as the range is already
+ * defined by its start and end points. The mask length is relevant for a single
+ * ranged entry instead: if @first_rule is 1 and @rule_count is 1, we ignore
+ * rule 2 above: @left becomes < 192, 168, 1, 0 >, @right becomes
+ * < 192, 168, 1, 255 >, and the mask length, calculated from the distances
+ * between leftmost and rightmost bucket indices for each group, would be 24.
+ *
+ * Return: mask length, in bits.
+ */
+static int pipapo_get_boundaries(struct nft_pipapo_field *f, int first_rule,
+				 int rule_count, u8 *left, u8 *right)
+{
+	u8 *l = left, *r = right;
+	int g, mask_len = 0;
+
+	for (g = 0; g < f->groups; g++) {
+		int b, x0, x1;
+
+		x0 = -1;
+		x1 = -1;
+		for (b = 0; b < NFT_PIPAPO_BUCKETS; b++) {
+			unsigned long *pos;
+
+			pos = f->lt + (g * NFT_PIPAPO_BUCKETS + b) * f->bsize;
+			if (test_bit(first_rule, pos) && x0 == -1)
+				x0 = b;
+			if (test_bit(first_rule + rule_count - 1, pos))
+				x1 = b;
+		}
+
+		if (g % 2) {
+			*(l++) |= x0 & 0x0f;
+			*(r++) |= x1 & 0x0f;
+		} else {
+			*l |= x0 << 4;
+			*r |= x1 << 4;
+		}
+
+		if (x1 - x0 == 0)
+			mask_len += 4;
+		else if (x1 - x0 == 1)
+			mask_len += 3;
+		else if (x1 - x0 == 3)
+			mask_len += 2;
+		else if (x1 - x0 == 7)
+			mask_len += 1;
+	}
+
+	return mask_len;
+}
+
+/**
+ * pipapo_match_field() - Match rules against byte ranges
+ * @f:		Field including the lookup table
+ * @first_rule:	First of associated rules originating from same entry
+ * @rule_count:	Amount of associated rules
+ * @start:	Start of range to be matched
+ * @end:	End of range to be matched
+ *
+ * Return: true on match, false otherwise.
+ */
+static bool pipapo_match_field(struct nft_pipapo_field *f,
+			       int first_rule, int rule_count,
+			       const u8 *start, const u8 *end)
+{
+	u8 right[NFT_PIPAPO_MAX_BYTES] = { 0 };
+	u8 left[NFT_PIPAPO_MAX_BYTES] = { 0 };
+
+	pipapo_get_boundaries(f, first_rule, rule_count, left, right);
+
+	return !memcmp(start, left, f->groups / NFT_PIPAPO_GROUPS_PER_BYTE) &&
+	       !memcmp(end, right, f->groups / NFT_PIPAPO_GROUPS_PER_BYTE);
+}
+
+/**
+ * nft_pipapo_remove() - Remove element given key, commit
+ * @net:	Network namespace
+ * @set:	nftables API set representation
+ * @elem:	nftables API element representation containing key data
+ *
+ * Similarly to nft_pipapo_activate(), this is used as commit operation by the
+ * API, but it's called once per element in the pending transaction, so we can't
+ * implement an actual, atomic commit operation. Closest we can get is to remove
+ * the matched element here, if any, and commit the updated matching data.
+ */
+static void nft_pipapo_remove(const struct net *net, const struct nft_set *set,
+			      const struct nft_set_elem *elem)
+{
+	const u8 *data = (const u8 *)elem->key.val.data;
+	struct nft_pipapo *priv = nft_set_priv(set);
+	struct nft_pipapo_match *m = priv->clone;
+	const struct nft_set_ext *ext;
+	int rules_f0, first_rule = 0;
+	struct nft_pipapo_elem *e;
+
+	ext = nft_set_elem_ext(set, elem->priv);
+	if (!nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) ||
+	    !(*nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END))
+		return;
+
+	e = pipapo_get(net, set, data, NFT_SET_ELEM_INTERVAL_END);
+	if (IS_ERR(e))
+		return;
+
+	while ((rules_f0 = pipapo_rules_same_key(m->f, first_rule))) {
+		union nft_pipapo_map_bucket rulemap[NFT_PIPAPO_MAX_FIELDS];
+		const u8 *match_start, *match_end;
+		struct nft_pipapo_field *f;
+		int i, start, rules_fx;
+
+		match_start = (const u8 *)nft_set_ext_key(&e->start->ext);
+		match_end = data;
+
+		start = first_rule;
+		rules_fx = rules_f0;
+
+		nft_pipapo_for_each_field(f, i, m) {
+			if (!pipapo_match_field(f, start, rules_fx,
+						match_start, match_end))
+				break;
+
+			rulemap[i].to = start;
+			rulemap[i].n = rules_fx;
+
+			rules_fx = f->mt[start].n;
+			start = f->mt[start].to;
+
+			match_start += NFT_PIPAPO_GROUPS_PADDED_SIZE(f->groups);
+			match_end += NFT_PIPAPO_GROUPS_PADDED_SIZE(f->groups);
+		}
+
+		if (i == m->field_count) {
+			priv->dirty = true;
+			pipapo_drop(m, rulemap);
+			pipapo_commit(set);
+			return;
+		}
+
+		first_rule += rules_f0;
+	}
+}
+
+/**
+ * nft_pipapo_walk() - Walk over elements
+ * @ctx:	nftables API context
+ * @set:	nftables API set representation
+ * @iter:	Iterator
+ *
+ * As elements are referenced in the mapping array for the last field, directly
+ * scan that array: there's no need to follow rule mappings from the first
+ * field.
+ *
+ * Note that we'll return two elements for each call, as each entry is
+ * represented as start and end elements.
+ */
+static void nft_pipapo_walk(const struct nft_ctx *ctx, struct nft_set *set,
+			    struct nft_set_iter *iter)
+{
+	struct nft_pipapo *priv = nft_set_priv(set);
+	struct nft_pipapo_match *m;
+	struct nft_pipapo_field *f;
+	int i, r;
+
+	rcu_read_lock();
+	m = rcu_dereference(priv->match);
+
+	if (unlikely(!m))
+		goto out;
+
+	for (i = 0, f = m->f; i < m->field_count - 1; i++, f++)
+		;
+
+	for (r = 0; r < f->rules; r++) {
+		struct nft_set_elem elem_start, elem_end;
+		struct nft_pipapo_elem *e;
+
+		if (r < f->rules - 1 && f->mt[r + 1].e == f->mt[r].e)
+			continue;
+
+		if (iter->count < iter->skip)
+			goto cont;
+
+		e = f->mt[r].e;
+		if (nft_set_elem_expired(&e->ext))
+			goto cont;
+
+		elem_start.priv = e->start;
+
+		iter->err = iter->fn(ctx, set, iter, &elem_start);
+		if (iter->err < 0)
+			goto out;
+
+		elem_end.priv = e;
+
+		iter->err = iter->fn(ctx, set, iter, &elem_end);
+		if (iter->err < 0)
+			goto out;
+
+cont:
+		iter->count += 2;
+	}
+
+out:
+	rcu_read_unlock();
+}
+
+/**
+ * nft_pipapo_privsize() - Return the size of private data for the set
+ * @nla:	netlink attributes, ignored as size doesn't depend on them
+ * @desc:	Set description, ignored as size doesn't depend on it
+ *
+ * Return: size of private data for this set implementation, in bytes
+ */
+static u64 nft_pipapo_privsize(const struct nlattr * const nla[],
+			       const struct nft_set_desc *desc)
+{
+	return sizeof(struct nft_pipapo);
+}
+
+/**
+ * nft_pipapo_estimate() - Estimate set size, space and lookup complexity
+ * @desc:	Set description, initial element count used here
+ * @features:	Flags: NFT_SET_SUBKEY needs to be there
+ * @est:	Storage for estimation data
+ *
+ * The size for this set type can vary dramatically, as it depends on the number
+ * of rules (composing netmasks) the entries expand to. We compute the worst
+ * case here, in order to ensure that other types are used if concatenation of
+ * ranges is not needed.
+ *
+ * In general, for a non-ranged entry or a single composing netmask, we need
+ * one bit in each of the sixteen NFT_PIPAPO_BUCKETS, for each 4-bit group (that
+ * is, each input bit needs four bits of matching data), plus a bucket in the
+ * mapping table for each field.
+ *
+ * Return: true
+ */
+static bool nft_pipapo_estimate(const struct nft_set_desc *desc, u32 features,
+				struct nft_set_estimate *est)
+{
+	if (!(features & NFT_SET_SUBKEY))
+		return false;
+
+	est->size = sizeof(struct nft_pipapo) + sizeof(struct nft_pipapo_match);
+
+	/* Worst-case with current amount of 32-bit VM registers (16 of them):
+	 * - 2 IPv6 addresses	8 registers
+	 * - 2 interface names	8 registers
+	 * that is, four 128-bit fields:
+	 */
+	est->size += sizeof(struct nft_pipapo_field) * 4;
+
+	/* expanding to worst-case ranges, 128 * 2 rules each, resulting in:
+	 * - 128 4-bit groups
+	 * - each set entry taking 256 bits in each bucket
+	 */
+	est->size += desc->size * NFT_PIPAPO_MAX_BITS / NFT_PIPAPO_GROUP_BITS *
+		     NFT_PIPAPO_BUCKETS * NFT_PIPAPO_MAX_BITS * 2 /
+		     BITS_PER_BYTE;
+
+	/* and we need mapping buckets, too */
+	est->size += desc->size * NFT_PIPAPO_MAP_NBITS *
+		     sizeof(union nft_pipapo_map_bucket);
+
+	est->lookup = NFT_SET_CLASS_O_LOG_N;
+
+	est->space = NFT_SET_CLASS_O_N;
+
+	return true;
+}
+
+/**
+ * nft_pipapo_init() - Initialise data for a set instance
+ * @set:	nftables API set representation
+ * @desc:	Set description
+ * @nla:	netlink attributes
+ *
+ * Validate number and size of fields passed as NFTA_SET_SUBKEY netlink
+ * attributes, initialise internal set parameters, current instance of matching
+ * data and a copy for subsequent insertions.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+static int nft_pipapo_init(const struct nft_set *set,
+			   const struct nft_set_desc *desc,
+			   const struct nlattr * const nla[])
+{
+	struct nft_pipapo *priv = nft_set_priv(set);
+	int rem, err = -EINVAL, field_count = 0, i;
+	struct nft_pipapo_match *m;
+	struct nft_pipapo_field *f;
+	struct nlattr *attr;
+	unsigned int klen;
+
+	if (!nla || !nla[NFTA_SET_SUBKEY])
+		return -EINVAL;
+
+	nla_for_each_nested(attr, nla[NFTA_SET_SUBKEY], rem) {
+		if (++field_count >= NFT_PIPAPO_MAX_FIELDS)
+			return -EINVAL;
+
+		if (nla_len(attr) != sizeof(klen) ||
+		    nla_type(attr) != NFTA_SET_SUBKEY_LEN)
+			return -EINVAL;
+	}
+
+	if (!field_count)
+		return -EINVAL;
+
+	m = kmalloc(sizeof(*priv->match) + sizeof(*f) * field_count,
+		    GFP_KERNEL);
+	if (!m)
+		return -ENOMEM;
+
+	m->field_count = field_count;
+	m->bsize_max = 0;
+
+	m->scratch = alloc_percpu(unsigned long *);
+	if (!m->scratch) {
+		err = -ENOMEM;
+		goto out_free;
+	}
+	for_each_possible_cpu(i)
+		*per_cpu_ptr(m->scratch, i) = NULL;
+
+	rcu_head_init(&m->rcu);
+
+	f = m->f;
+	priv->width = 0;
+	nla_for_each_nested(attr, nla[NFTA_SET_SUBKEY], rem) {
+		klen = ntohl(nla_get_be32(attr));
+		if (!klen || klen % NFT_PIPAPO_GROUP_BITS)
+			goto out_free;
+
+		if (klen > NFT_PIPAPO_MAX_BITS)
+			goto out_free;
+
+		priv->groups += f->groups = klen / NFT_PIPAPO_GROUP_BITS;
+		priv->width += round_up(klen / BITS_PER_BYTE, sizeof(u32));
+
+		f->bsize = 0;
+		f->rules = 0;
+		f->lt = NULL;
+		f->mt = NULL;
+
+		f++;
+	}
+
+	/* Create an initial clone of matching data for next insertion */
+	priv->clone = pipapo_clone(m);
+	if (IS_ERR(priv->clone)) {
+		err = PTR_ERR(priv->clone);
+		goto out_free;
+	}
+
+	priv->dirty = false;
+
+	rcu_assign_pointer(priv->match, m);
+
+	return 0;
+
+out_free:
+	free_percpu(m->scratch);
+	kfree(m);
+
+	return err;
+}
+
+/**
+ * nft_pipapo_destroy() - Free private data for set and all committed elements
+ * @set:	nftables API set representation
+ */
+static void nft_pipapo_destroy(const struct nft_set *set)
+{
+	struct nft_pipapo *priv = nft_set_priv(set);
+	struct nft_pipapo_match *m;
+	struct nft_pipapo_field *f;
+	int i, r, cpu;
+
+	m = rcu_dereference_protected(priv->match, true);
+	if (m) {
+		rcu_barrier();
+
+		for (i = 0, f = m->f; i < m->field_count - 1; i++, f++)
+			;
+
+		for (r = 0; r < f->rules; r++) {
+			struct nft_pipapo_elem *e;
+
+			if (r < f->rules - 1 && f->mt[r + 1].e == f->mt[r].e)
+				continue;
+
+			e = f->mt[r].e;
+
+			nft_set_elem_destroy(set, e->start, true);
+			nft_set_elem_destroy(set, e, true);
+		}
+
+		for_each_possible_cpu(cpu)
+			kfree(*per_cpu_ptr(m->scratch, cpu));
+		free_percpu(m->scratch);
+
+		pipapo_free_fields(m);
+		kfree(m);
+		priv->match = NULL;
+	}
+
+	if (priv->clone) {
+		for_each_possible_cpu(cpu)
+			kfree(*per_cpu_ptr(priv->clone->scratch, cpu));
+		free_percpu(priv->clone->scratch);
+
+		pipapo_free_fields(priv->clone);
+		kfree(priv->clone);
+		priv->clone = NULL;
+	}
+}
+
+/**
+ * nft_pipapo_gc_init() - Initialise garbage collection
+ * @set:	nftables API set representation
+ *
+ * Instead of actually setting up a periodic work for garbage collection, as
+ * this operation requires a swap of matching data with the working copy, we'll
+ * do that opportunistically with other commit operations if the interval is
+ * elapsed, so we just need to set the current jiffies timestamp here.
+ */
+static void nft_pipapo_gc_init(const struct nft_set *set)
+{
+	struct nft_pipapo *priv = nft_set_priv(set);
+
+	priv->last_gc = jiffies;
+}
+
+struct nft_set_type nft_set_pipapo_type __read_mostly = {
+	.owner		= THIS_MODULE,
+	.features	= NFT_SET_INTERVAL | NFT_SET_MAP | NFT_SET_OBJECT |
+			  NFT_SET_TIMEOUT | NFT_SET_SUBKEY,
+	.ops		= {
+		.lookup		= nft_pipapo_lookup,
+		.insert		= nft_pipapo_insert,
+		.activate	= nft_pipapo_activate,
+		.deactivate	= nft_pipapo_deactivate,
+		.flush		= nft_pipapo_flush,
+		.remove		= nft_pipapo_remove,
+		.walk		= nft_pipapo_walk,
+		.get		= nft_pipapo_get,
+		.privsize	= nft_pipapo_privsize,
+		.estimate	= nft_pipapo_estimate,
+		.init		= nft_pipapo_init,
+		.destroy	= nft_pipapo_destroy,
+		.gc_init	= nft_pipapo_gc_init,
+		.elemsize	= offsetof(struct nft_pipapo_elem, ext),
+	},
+};
