```// SPDX-License-Identifier: GPL-2.0-only

/* PIPAPO: PIle PAcket POlicies: set for arbitrary concatenations of ranges
*
* Copyright (c) 2019-2020 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:             0x66  0x42
*
*
* 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:             0x66  0x42
*
*      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.
*      https://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.
*      https://www.sigcomm.org/sites/default/files/ccr/papers/2014/August/2619239-2626294.pdf
*/

#include <linux/kernel.h>
#include <linux/init.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 <linux/bitmap.h>
#include <linux/bitops.h>

#include "nft_set_pipapo_avx2.h"
#include "nft_set_pipapo.h"

/* Current working bitmap index, toggled between field matches */
static DEFINE_PER_CPU(bool, nft_pipapo_scratch_index);

/**
* 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.
*/
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 (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
* @key:	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;

local_bh_disable();

map_index = raw_cpu_read(nft_pipapo_scratch_index);

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;
int b;

/* For each bit group: select lookup table bucket depending on
* packet bytes value, then AND bucket value
*/
if (likely(f->bb == 8))
pipapo_and_field_buckets_8bit(f, res_map, rp);
else
pipapo_and_field_buckets_4bit(f, res_map, rp);
NFT_PIPAPO_GROUP_BITS_ARE_8_OR_4;

rp += f->groups / NFT_PIPAPO_GROUPS_PER_BYTE(f);

/* 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) {
raw_cpu_write(nft_pipapo_scratch_index, map_index);
local_bh_enable();

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.
*/
raw_cpu_write(nft_pipapo_scratch_index, map_index);
local_bh_enable();

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);
}

out:
local_bh_enable();
return false;
}

/**
* pipapo_get() - Get matching element reference given key data
* @net:	Network namespace
* @set:	nftables API set representation
* @data:	Key data to be matched against existing elements
* @genmask:	If set, check that element is active in given genmask
*
* 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 struct nft_pipapo_elem *pipapo_get(const struct net *net,
const struct nft_set *set,
const u8 *data, u8 genmask)
{
struct nft_pipapo_elem *ret = ERR_PTR(-ENOENT);
struct nft_pipapo *priv = nft_set_priv(set);
struct nft_pipapo_match *m = priv->clone;
unsigned long *res_map, *fill_map = NULL;
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;
int b;

/* For each bit group: select lookup table bucket depending on
* packet bytes value, then AND bucket value
*/
if (f->bb == 8)
pipapo_and_field_buckets_8bit(f, res_map, data);
else if (f->bb == 4)
pipapo_and_field_buckets_4bit(f, res_map, data);
else
BUG();

data += f->groups / NFT_PIPAPO_GROUPS_PER_BYTE(f);

/* 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) ||
(genmask &&
!nft_set_elem_active(&f->mt[b].e->ext, genmask)))
goto next_match;

ret = f->mt[b].e;
goto out;
}

data += NFT_PIPAPO_GROUPS_PADDING(f);

/* 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:	Unused
*/
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,
nft_genmask_cur(net));
}

/**
* 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);
#ifdef NFT_PIPAPO_ALIGN
new_bucket_size = roundup(new_bucket_size,
NFT_PIPAPO_ALIGN / sizeof(*new_lt));
#endif

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(f->bb) *
new_bucket_size * sizeof(*new_lt) +
NFT_PIPAPO_ALIGN_HEADROOM,
GFP_KERNEL);
if (!new_lt)
return -ENOMEM;

new_p = NFT_PIPAPO_LT_ALIGN(new_lt);
old_p = NFT_PIPAPO_LT_ALIGN(old_lt);

for (group = 0; group < f->groups; group++) {
for (bucket = 0; bucket < NFT_PIPAPO_BUCKETS(f->bb); 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;
NFT_PIPAPO_LT_ASSIGN(f, 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 = NFT_PIPAPO_LT_ALIGN(f->lt);
pos += f->bsize * NFT_PIPAPO_BUCKETS(f->bb) * group;
pos += f->bsize * v;

__set_bit(rule, pos);
}

/**
* pipapo_lt_4b_to_8b() - Switch lookup table group width from 4 bits to 8 bits
* @old_groups:	Number of current groups
* @bsize:	Size of one bucket, in longs
* @old_lt:	Pointer to the current lookup table
* @new_lt:	Pointer to the new, pre-allocated lookup table
*
* Each bucket with index b in the new lookup table, belonging to group g, is
* filled with the bit intersection between:
* - bucket with index given by the upper 4 bits of b, from group g, and
* - bucket with index given by the lower 4 bits of b, from group g + 1
*
* That is, given buckets from the new lookup table N(x, y) and the old lookup
* table O(x, y), with x bucket index, and y group index:
*
*	N(b, g) := O(b / 16, g) & O(b % 16, g + 1)
*
* This ensures equivalence of the matching results on lookup. Two examples in
* pictures:
*
*              bucket
*  group  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 ... 254 255
*    0                ^
*    1                |                                                 ^
*   ...             ( & )                                               |
*                  /     \                                              |
*                 /       \                                         .-( & )-.
*                /  bucket \                                        |       |
*      group  0 / 1   2   3 \ 4   5   6   7   8   9  10  11  12  13 |14  15 |
*        0     /             \                                      |       |
*        1                    \                                     |       |
*        2                                                          |     --'
*        3                                                          '-
*       ...
*/
static void pipapo_lt_4b_to_8b(int old_groups, int bsize,
unsigned long *old_lt, unsigned long *new_lt)
{
int g, b, i;

for (g = 0; g < old_groups / 2; g++) {
int src_g0 = g * 2, src_g1 = g * 2 + 1;

for (b = 0; b < NFT_PIPAPO_BUCKETS(8); b++) {
int src_b0 = b / NFT_PIPAPO_BUCKETS(4);
int src_b1 = b % NFT_PIPAPO_BUCKETS(4);
int src_i0 = src_g0 * NFT_PIPAPO_BUCKETS(4) + src_b0;
int src_i1 = src_g1 * NFT_PIPAPO_BUCKETS(4) + src_b1;

for (i = 0; i < bsize; i++) {
*new_lt = old_lt[src_i0 * bsize + i] &
old_lt[src_i1 * bsize + i];
new_lt++;
}
}
}
}

/**
* pipapo_lt_8b_to_4b() - Switch lookup table group width from 8 bits to 4 bits
* @old_groups:	Number of current groups
* @bsize:	Size of one bucket, in longs
* @old_lt:	Pointer to the current lookup table
* @new_lt:	Pointer to the new, pre-allocated lookup table
*
* Each bucket with index b in the new lookup table, belonging to group g, is
* filled with the bit union of:
* - all the buckets with index such that the upper four bits of the lower byte
*   equal b, from group g, with g odd
* - all the buckets with index such that the lower four bits equal b, from
*   group g, with g even
*
* That is, given buckets from the new lookup table N(x, y) and the old lookup
* table O(x, y), with x bucket index, and y group index:
*
*	- with g odd:  N(b, g) := U(O(x, g) for each x : x = (b & 0xf0) >> 4)
*	- with g even: N(b, g) := U(O(x, g) for each x : x = b & 0x0f)
*
* where U() denotes the arbitrary union operation (binary OR of n terms). This
* ensures equivalence of the matching results on lookup.
*/
static void pipapo_lt_8b_to_4b(int old_groups, int bsize,
unsigned long *old_lt, unsigned long *new_lt)
{
int g, b, bsrc, i;

memset(new_lt, 0, old_groups * 2 * NFT_PIPAPO_BUCKETS(4) * bsize *
sizeof(unsigned long));

for (g = 0; g < old_groups * 2; g += 2) {
int src_g = g / 2;

for (b = 0; b < NFT_PIPAPO_BUCKETS(4); b++) {
for (bsrc = NFT_PIPAPO_BUCKETS(8) * src_g;
bsrc < NFT_PIPAPO_BUCKETS(8) * (src_g + 1);
bsrc++) {
if (((bsrc & 0xf0) >> 4) != b)
continue;

for (i = 0; i < bsize; i++)
new_lt[i] |= old_lt[bsrc * bsize + i];
}

new_lt += bsize;
}

for (b = 0; b < NFT_PIPAPO_BUCKETS(4); b++) {
for (bsrc = NFT_PIPAPO_BUCKETS(8) * src_g;
bsrc < NFT_PIPAPO_BUCKETS(8) * (src_g + 1);
bsrc++) {
if ((bsrc & 0x0f) != b)
continue;

for (i = 0; i < bsize; i++)
new_lt[i] |= old_lt[bsrc * bsize + i];
}

new_lt += bsize;
}
}
}

/**
* pipapo_lt_bits_adjust() - Adjust group size for lookup table if needed
* @f:		Field containing lookup table
*/
static void pipapo_lt_bits_adjust(struct nft_pipapo_field *f)
{
unsigned long *new_lt;
int groups, bb;
size_t lt_size;

lt_size = f->groups * NFT_PIPAPO_BUCKETS(f->bb) * f->bsize *
sizeof(*f->lt);

if (f->bb == NFT_PIPAPO_GROUP_BITS_SMALL_SET &&
lt_size > NFT_PIPAPO_LT_SIZE_HIGH) {
groups = f->groups * 2;
bb = NFT_PIPAPO_GROUP_BITS_LARGE_SET;

lt_size = groups * NFT_PIPAPO_BUCKETS(bb) * f->bsize *
sizeof(*f->lt);
} else if (f->bb == NFT_PIPAPO_GROUP_BITS_LARGE_SET &&
lt_size < NFT_PIPAPO_LT_SIZE_LOW) {
groups = f->groups / 2;
bb = NFT_PIPAPO_GROUP_BITS_SMALL_SET;

lt_size = groups * NFT_PIPAPO_BUCKETS(bb) * f->bsize *
sizeof(*f->lt);

/* Don't increase group width if the resulting lookup table size
* would exceed the upper size threshold for a "small" set.
*/
if (lt_size > NFT_PIPAPO_LT_SIZE_HIGH)
return;
} else {
return;
}

new_lt = kvzalloc(lt_size + NFT_PIPAPO_ALIGN_HEADROOM, GFP_KERNEL);
if (!new_lt)
return;

NFT_PIPAPO_GROUP_BITS_ARE_8_OR_4;
if (f->bb == 4 && bb == 8) {
pipapo_lt_4b_to_8b(f->groups, f->bsize,
NFT_PIPAPO_LT_ALIGN(f->lt),
NFT_PIPAPO_LT_ALIGN(new_lt));
} else if (f->bb == 8 && bb == 4) {
pipapo_lt_8b_to_4b(f->groups, f->bsize,
NFT_PIPAPO_LT_ALIGN(f->lt),
NFT_PIPAPO_LT_ALIGN(new_lt));
} else {
BUG();
}

f->groups = groups;
f->bb = bb;
kvfree(f->lt);
NFT_PIPAPO_LT_ASSIGN(f, new_lt);
}

/**
* 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, bit_offset = 0;

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;

v = k[group / (BITS_PER_BYTE / f->bb)];
v &= GENMASK(BITS_PER_BYTE - bit_offset - 1, 0);
v >>= (BITS_PER_BYTE - bit_offset) - f->bb;

bit_offset += f->bb;
bit_offset %= BITS_PER_BYTE;

if (mask_bits >= (group + 1) * f->bb) {
/* Not masked */
pipapo_bucket_set(f, rule, group, v);
} else if (mask_bits <= group * f->bb) {
/* Completely masked */
for (i = 0; i < NFT_PIPAPO_BUCKETS(f->bb); i++)
pipapo_bucket_set(f, rule, group, i);
} else {
/* The mask limit falls on this group */
mask = GENMASK(f->bb - 1, 0);
mask >>= mask_bits - group * f->bb;
for (i = 0; i < NFT_PIPAPO_BUCKETS(f->bb); i++) {
if ((i & ~mask) == (v & ~mask))
pipapo_bucket_set(f, rule, group, i);
}
}
}

pipapo_lt_bits_adjust(f);

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;
}
}

/**
* pipapo_expand() - Expand to composing netmasks, 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
* @e:		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
* @clone:	Copy of matching data with pending insertions and deletions
* @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 *clone,
unsigned long bsize_max)
{
int i;

for_each_possible_cpu(i) {
unsigned long *scratch;
#ifdef NFT_PIPAPO_ALIGN
unsigned long *scratch_aligned;
#endif

scratch = kzalloc_node(bsize_max * sizeof(*scratch) * 2 +
NFT_PIPAPO_ALIGN_HEADROOM,
GFP_KERNEL, cpu_to_node(i));
if (!scratch) {
/* On failure, there's no need to undo previous
* allocations: this means that some scratch maps have
* a bigger allocated size now (this is only called on
* insertion), but the extra space won't be used by any
* CPU as new elements are not inserted and m->bsize_max
* is not updated.
*/
return -ENOMEM;
}

kfree(*per_cpu_ptr(clone->scratch, i));

*per_cpu_ptr(clone->scratch, i) = scratch;

#ifdef NFT_PIPAPO_ALIGN
scratch_aligned = NFT_PIPAPO_LT_ALIGN(scratch);
*per_cpu_ptr(clone->scratch_aligned, i) = scratch_aligned;
#endif
}

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
* @ext2:	Filled with pointer to &struct nft_set_ext in inserted element
*
* 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);
union nft_pipapo_map_bucket rulemap[NFT_PIPAPO_MAX_FIELDS];
const u8 *start = (const u8 *)elem->key.val.data, *end;
struct nft_pipapo_elem *e = elem->priv, *dup;
struct nft_pipapo *priv = nft_set_priv(set);
struct nft_pipapo_match *m = priv->clone;
u8 genmask = nft_genmask_next(net);
struct nft_pipapo_field *f;
int i, bsize_max, err = 0;

if (nft_set_ext_exists(ext, NFT_SET_EXT_KEY_END))
end = (const u8 *)nft_set_ext_key_end(ext)->data;
else
end = start;

dup = pipapo_get(net, set, start, genmask);
if (!IS_ERR(dup)) {
/* Check if we already have the same exact entry */
const struct nft_data *dup_key, *dup_end;

dup_key = nft_set_ext_key(&dup->ext);
if (nft_set_ext_exists(&dup->ext, NFT_SET_EXT_KEY_END))
dup_end = nft_set_ext_key_end(&dup->ext);
else
dup_end = dup_key;

if (!memcmp(start, dup_key->data, sizeof(*dup_key->data)) &&
!memcmp(end, dup_end->data, sizeof(*dup_end->data))) {
*ext2 = &dup->ext;
return -EEXIST;
}

return -ENOTEMPTY;
}

if (PTR_ERR(dup) == -ENOENT) {
/* Look for partially overlapping entries */
dup = pipapo_get(net, set, end, nft_genmask_next(net));
}

if (PTR_ERR(dup) != -ENOENT) {
if (IS_ERR(dup))
return PTR_ERR(dup);
*ext2 = &dup->ext;
return -ENOTEMPTY;
}

/* Validate */
nft_pipapo_for_each_field(f, i, m) {
const u8 *start_p = start, *end_p = end;

if (f->rules >= (unsigned long)NFT_PIPAPO_RULE0_MAX)
return -ENOSPC;

if (memcmp(start_p, end_p,
f->groups / NFT_PIPAPO_GROUPS_PER_BYTE(f)) > 0)
return -EINVAL;

start_p += NFT_PIPAPO_GROUPS_PADDED_SIZE(f);
end_p += NFT_PIPAPO_GROUPS_PADDED_SIZE(f);
}

/* Insert */
priv->dirty = true;

bsize_max = m->bsize_max;

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(f));
if (!ret)
ret = pipapo_insert(f, start, f->groups * f->bb);
else
ret = pipapo_expand(f, start, end, f->groups * f->bb);

if (f->bsize > bsize_max)
bsize_max = f->bsize;

rulemap[i].n = ret;

start += NFT_PIPAPO_GROUPS_PADDED_SIZE(f);
end += NFT_PIPAPO_GROUPS_PADDED_SIZE(f);
}

if (!*get_cpu_ptr(m->scratch) || bsize_max > m->bsize_max) {
put_cpu_ptr(m->scratch);

err = pipapo_realloc_scratch(m, bsize_max);
if (err)
return err;

m->bsize_max = bsize_max;
} else {
put_cpu_ptr(m->scratch);
}

*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;

#ifdef NFT_PIPAPO_ALIGN
new->scratch_aligned = alloc_percpu(*new->scratch_aligned);
if (!new->scratch_aligned)
goto out_scratch;
#endif

rcu_head_init(&new->rcu);

src = old->f;
dst = new->f;

for (i = 0; i < old->field_count; i++) {
unsigned long *new_lt;

memcpy(dst, src, offsetof(struct nft_pipapo_field, lt));

new_lt = kvzalloc(src->groups * NFT_PIPAPO_BUCKETS(src->bb) *
src->bsize * sizeof(*dst->lt) +
NFT_PIPAPO_ALIGN_HEADROOM,
GFP_KERNEL);
if (!new_lt)
goto out_lt;

NFT_PIPAPO_LT_ASSIGN(dst, new_lt);

memcpy(NFT_PIPAPO_LT_ALIGN(new_lt),
NFT_PIPAPO_LT_ALIGN(src->lt),
src->bsize * sizeof(*dst->lt) *
src->groups * NFT_PIPAPO_BUCKETS(src->bb));

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--;
}
#ifdef NFT_PIPAPO_ALIGN
free_percpu(new->scratch_aligned);
#endif
out_scratch:
free_percpu(new->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 = NFT_PIPAPO_LT_ALIGN(f->lt) + g *
NFT_PIPAPO_BUCKETS(f->bb) * f->bsize;

for (b = 0; b < NFT_PIPAPO_BUCKETS(f->bb); 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_lt_bits_adjust(f);
}
}

/**
* 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, 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));

#ifdef NFT_PIPAPO_ALIGN
free_percpu(m->scratch_aligned);
#endif
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. 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)
{
struct nft_pipapo_elem *e;

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);

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)
{
struct nft_pipapo_elem *e;

e = pipapo_get(net, set, data, nft_genmask_next(net));
if (IS_ERR(e))
return NULL;

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, strictly speaking, a 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)
{
int g, mask_len = 0, bit_offset = 0;
u8 *l = left, *r = right;

for (g = 0; g < f->groups; g++) {
int b, x0, x1;

x0 = -1;
x1 = -1;
for (b = 0; b < NFT_PIPAPO_BUCKETS(f->bb); b++) {
unsigned long *pos;

pos = NFT_PIPAPO_LT_ALIGN(f->lt) +
(g * NFT_PIPAPO_BUCKETS(f->bb) + b) * f->bsize;
if (test_bit(first_rule, pos) && x0 == -1)
x0 = b;
if (test_bit(first_rule + rule_count - 1, pos))
x1 = b;
}

*l |= x0 << (BITS_PER_BYTE - f->bb - bit_offset);
*r |= x1 << (BITS_PER_BYTE - f->bb - bit_offset);

bit_offset += f->bb;
if (bit_offset >= BITS_PER_BYTE) {
bit_offset %= BITS_PER_BYTE;
l++;
r++;
}

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(f)) &&
!memcmp(end, right, f->groups / NFT_PIPAPO_GROUPS_PER_BYTE(f));
}

/**
* 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 this as a single 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)
{
struct nft_pipapo *priv = nft_set_priv(set);
struct nft_pipapo_match *m = priv->clone;
struct nft_pipapo_elem *e = elem->priv;
int rules_f0, first_rule = 0;
const u8 *data;

data = (const u8 *)nft_set_ext_key(&e->ext);

e = pipapo_get(net, set, data, 0);
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 = data;
match_end = (const u8 *)nft_set_ext_key_end(&e->ext)->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);
match_end += NFT_PIPAPO_GROUPS_PADDED_SIZE(f);
}

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.
*/
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_pipapo_elem *e;
struct nft_set_elem elem;

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.priv = e;

iter->err = iter->fn(ctx, set, iter, &elem);
if (iter->err < 0)
goto out;

cont:
iter->count++;
}

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() - Set size, space and lookup complexity
* @desc:	Set description, element count and field description used
* @features:	Flags: NFT_SET_INTERVAL needs to be there
* @est:	Storage for estimation data
*
* Return: true if set description is compatible, false otherwise
*/
static bool nft_pipapo_estimate(const struct nft_set_desc *desc, u32 features,
struct nft_set_estimate *est)
{
if (!(features & NFT_SET_INTERVAL) ||
desc->field_count < NFT_PIPAPO_MIN_FIELDS)
return false;

est->size = pipapo_estimate_size(desc);
if (!est->size)
return false;

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_DESC_CONCAT 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);
struct nft_pipapo_match *m;
struct nft_pipapo_field *f;
int err, i, field_count;

field_count = desc->field_count ? : 1;

if (field_count > NFT_PIPAPO_MAX_FIELDS)
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_scratch;
}
for_each_possible_cpu(i)
*per_cpu_ptr(m->scratch, i) = NULL;

#ifdef NFT_PIPAPO_ALIGN
m->scratch_aligned = alloc_percpu(unsigned long *);
if (!m->scratch_aligned) {
err = -ENOMEM;
goto out_free;
}
for_each_possible_cpu(i)
*per_cpu_ptr(m->scratch_aligned, i) = NULL;
#endif

rcu_head_init(&m->rcu);

nft_pipapo_for_each_field(f, i, m) {
int len = desc->field_len[i] ? : set->klen;

f->bb = NFT_PIPAPO_GROUP_BITS_INIT;
f->groups = len * NFT_PIPAPO_GROUPS_PER_BYTE(f);

priv->width += round_up(len, sizeof(u32));

f->bsize = 0;
f->rules = 0;
NFT_PIPAPO_LT_ASSIGN(f, NULL);
f->mt = NULL;
}

/* 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:
#ifdef NFT_PIPAPO_ALIGN
free_percpu(m->scratch_aligned);
#endif
free_percpu(m->scratch);
out_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, true);
}

#ifdef NFT_PIPAPO_ALIGN
free_percpu(m->scratch_aligned);
#endif
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) {
#ifdef NFT_PIPAPO_ALIGN
free_percpu(priv->clone->scratch_aligned);
#endif
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;
}

const struct nft_set_type nft_set_pipapo_type = {
.features	= NFT_SET_INTERVAL | NFT_SET_MAP | NFT_SET_OBJECT |
NFT_SET_TIMEOUT,
.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),
},
};

#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
const struct nft_set_type nft_set_pipapo_avx2_type = {
.features	= NFT_SET_INTERVAL | NFT_SET_MAP | NFT_SET_OBJECT |
NFT_SET_TIMEOUT,
.ops		= {
.lookup		= nft_pipapo_avx2_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_avx2_estimate,
.init		= nft_pipapo_init,
.destroy	= nft_pipapo_destroy,
.gc_init	= nft_pipapo_gc_init,
.elemsize	= offsetof(struct nft_pipapo_elem, ext),
},
};
#endif```