| // 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 successful 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 |
| * transaction 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); |
| } |
| |
| INDIRECT_CALLABLE_SCOPE |
| 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_ctx *ctx, |
| 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) |
| nf_tables_set_elem_destroy(ctx, set, be); |
| } |
| |
| 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, |
| }, |
| }; |