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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
- */
- #include <linux/kernel.h>
- #include <linux/init.h>
- #include <linux/module.h>
- #include <linux/list.h>
- #include <linux/netlink.h>
- #include <linux/netfilter.h>
- #include <linux/netfilter/nf_tables.h>
- #include <net/netfilter/nf_tables_core.h>
- struct nft_bitmap_elem {
- struct list_head head;
- struct nft_set_ext ext;
- };
- /* This bitmap uses two bits to represent one element. These two bits determine
- * the element state in the current and the future generation.
- *
- * An element can be in three states. The generation cursor is represented using
- * the ^ character, note that this cursor shifts on every succesful transaction.
- * If no transaction is going on, we observe all elements are in the following
- * state:
- *
- * 11 = this element is active in the current generation. In case of no updates,
- * ^ it stays active in the next generation.
- * 00 = this element is inactive in the current generation. In case of no
- * ^ updates, it stays inactive in the next generation.
- *
- * On transaction handling, we observe these two temporary states:
- *
- * 01 = this element is inactive in the current generation and it becomes active
- * ^ in the next one. This happens when the element is inserted but commit
- * path has not yet been executed yet, so activation is still pending. On
- * transaction abortion, the element is removed.
- * 10 = this element is active in the current generation and it becomes inactive
- * ^ in the next one. This happens when the element is deactivated but commit
- * path has not yet been executed yet, so removal is still pending. On
- * transation abortion, the next generation bit is reset to go back to
- * restore its previous state.
- */
- struct nft_bitmap {
- struct list_head list;
- u16 bitmap_size;
- u8 bitmap[];
- };
- static inline void nft_bitmap_location(const struct nft_set *set,
- const void *key,
- u32 *idx, u32 *off)
- {
- u32 k;
- if (set->klen == 2)
- k = *(u16 *)key;
- else
- k = *(u8 *)key;
- k <<= 1;
- *idx = k / BITS_PER_BYTE;
- *off = k % BITS_PER_BYTE;
- }
- /* Fetch the two bits that represent the element and check if it is active based
- * on the generation mask.
- */
- static inline bool
- nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask)
- {
- return (bitmap[idx] & (0x3 << off)) & (genmask << off);
- }
- static bool nft_bitmap_lookup(const struct net *net, const struct nft_set *set,
- const u32 *key, const struct nft_set_ext **ext)
- {
- const struct nft_bitmap *priv = nft_set_priv(set);
- u8 genmask = nft_genmask_cur(net);
- u32 idx, off;
- nft_bitmap_location(set, key, &idx, &off);
- return nft_bitmap_active(priv->bitmap, idx, off, genmask);
- }
- static struct nft_bitmap_elem *
- nft_bitmap_elem_find(const struct nft_set *set, struct nft_bitmap_elem *this,
- u8 genmask)
- {
- const struct nft_bitmap *priv = nft_set_priv(set);
- struct nft_bitmap_elem *be;
- list_for_each_entry_rcu(be, &priv->list, head) {
- if (memcmp(nft_set_ext_key(&be->ext),
- nft_set_ext_key(&this->ext), set->klen) ||
- !nft_set_elem_active(&be->ext, genmask))
- continue;
- return be;
- }
- return NULL;
- }
- static void *nft_bitmap_get(const struct net *net, const struct nft_set *set,
- const struct nft_set_elem *elem, unsigned int flags)
- {
- const struct nft_bitmap *priv = nft_set_priv(set);
- u8 genmask = nft_genmask_cur(net);
- struct nft_bitmap_elem *be;
- list_for_each_entry_rcu(be, &priv->list, head) {
- if (memcmp(nft_set_ext_key(&be->ext), elem->key.val.data, set->klen) ||
- !nft_set_elem_active(&be->ext, genmask))
- continue;
- return be;
- }
- return ERR_PTR(-ENOENT);
- }
- static int nft_bitmap_insert(const struct net *net, const struct nft_set *set,
- const struct nft_set_elem *elem,
- struct nft_set_ext **ext)
- {
- struct nft_bitmap *priv = nft_set_priv(set);
- struct nft_bitmap_elem *new = elem->priv, *be;
- u8 genmask = nft_genmask_next(net);
- u32 idx, off;
- be = nft_bitmap_elem_find(set, new, genmask);
- if (be) {
- *ext = &be->ext;
- return -EEXIST;
- }
- nft_bitmap_location(set, nft_set_ext_key(&new->ext), &idx, &off);
- /* Enter 01 state. */
- priv->bitmap[idx] |= (genmask << off);
- list_add_tail_rcu(&new->head, &priv->list);
- return 0;
- }
- static void nft_bitmap_remove(const struct net *net,
- const struct nft_set *set,
- const struct nft_set_elem *elem)
- {
- struct nft_bitmap *priv = nft_set_priv(set);
- struct nft_bitmap_elem *be = elem->priv;
- u8 genmask = nft_genmask_next(net);
- u32 idx, off;
- nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
- /* Enter 00 state. */
- priv->bitmap[idx] &= ~(genmask << off);
- list_del_rcu(&be->head);
- }
- static void nft_bitmap_activate(const struct net *net,
- const struct nft_set *set,
- const struct nft_set_elem *elem)
- {
- struct nft_bitmap *priv = nft_set_priv(set);
- struct nft_bitmap_elem *be = elem->priv;
- u8 genmask = nft_genmask_next(net);
- u32 idx, off;
- nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
- /* Enter 11 state. */
- priv->bitmap[idx] |= (genmask << off);
- nft_set_elem_change_active(net, set, &be->ext);
- }
- static bool nft_bitmap_flush(const struct net *net,
- const struct nft_set *set, void *_be)
- {
- struct nft_bitmap *priv = nft_set_priv(set);
- u8 genmask = nft_genmask_next(net);
- struct nft_bitmap_elem *be = _be;
- u32 idx, off;
- nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
- /* Enter 10 state, similar to deactivation. */
- priv->bitmap[idx] &= ~(genmask << off);
- nft_set_elem_change_active(net, set, &be->ext);
- return true;
- }
- static void *nft_bitmap_deactivate(const struct net *net,
- const struct nft_set *set,
- const struct nft_set_elem *elem)
- {
- struct nft_bitmap *priv = nft_set_priv(set);
- struct nft_bitmap_elem *this = elem->priv, *be;
- u8 genmask = nft_genmask_next(net);
- u32 idx, off;
- nft_bitmap_location(set, elem->key.val.data, &idx, &off);
- be = nft_bitmap_elem_find(set, this, genmask);
- if (!be)
- return NULL;
- /* Enter 10 state. */
- priv->bitmap[idx] &= ~(genmask << off);
- nft_set_elem_change_active(net, set, &be->ext);
- return be;
- }
- static void nft_bitmap_walk(const struct nft_ctx *ctx,
- struct nft_set *set,
- struct nft_set_iter *iter)
- {
- const struct nft_bitmap *priv = nft_set_priv(set);
- struct nft_bitmap_elem *be;
- struct nft_set_elem elem;
- list_for_each_entry_rcu(be, &priv->list, head) {
- if (iter->count < iter->skip)
- goto cont;
- if (!nft_set_elem_active(&be->ext, iter->genmask))
- goto cont;
- elem.priv = be;
- iter->err = iter->fn(ctx, set, iter, &elem);
- if (iter->err < 0)
- return;
- cont:
- iter->count++;
- }
- }
- /* The bitmap size is pow(2, key length in bits) / bits per byte. This is
- * multiplied by two since each element takes two bits. For 8 bit keys, the
- * bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
- */
- static inline u32 nft_bitmap_size(u32 klen)
- {
- return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
- }
- static inline u64 nft_bitmap_total_size(u32 klen)
- {
- return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
- }
- static u64 nft_bitmap_privsize(const struct nlattr * const nla[],
- const struct nft_set_desc *desc)
- {
- u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
- return nft_bitmap_total_size(klen);
- }
- static int nft_bitmap_init(const struct nft_set *set,
- const struct nft_set_desc *desc,
- const struct nlattr * const nla[])
- {
- struct nft_bitmap *priv = nft_set_priv(set);
- INIT_LIST_HEAD(&priv->list);
- priv->bitmap_size = nft_bitmap_size(set->klen);
- return 0;
- }
- static void nft_bitmap_destroy(const struct nft_set *set)
- {
- struct nft_bitmap *priv = nft_set_priv(set);
- struct nft_bitmap_elem *be, *n;
- list_for_each_entry_safe(be, n, &priv->list, head)
- nft_set_elem_destroy(set, be, true);
- }
- static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
- struct nft_set_estimate *est)
- {
- /* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
- if (desc->klen > 2)
- return false;
- else if (desc->expr)
- return false;
- est->size = nft_bitmap_total_size(desc->klen);
- est->lookup = NFT_SET_CLASS_O_1;
- est->space = NFT_SET_CLASS_O_1;
- return true;
- }
- const struct nft_set_type nft_set_bitmap_type = {
- .ops = {
- .privsize = nft_bitmap_privsize,
- .elemsize = offsetof(struct nft_bitmap_elem, ext),
- .estimate = nft_bitmap_estimate,
- .init = nft_bitmap_init,
- .destroy = nft_bitmap_destroy,
- .insert = nft_bitmap_insert,
- .remove = nft_bitmap_remove,
- .deactivate = nft_bitmap_deactivate,
- .flush = nft_bitmap_flush,
- .activate = nft_bitmap_activate,
- .lookup = nft_bitmap_lookup,
- .walk = nft_bitmap_walk,
- .get = nft_bitmap_get,
- },
- };
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