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![Pablo Neira Ayuso](/assets/img/avatar_default.png)
Initialize set lookup matching element to NULL. Otherwise, the NFT_LOOKUP_F_INV flag reverses the matching logic and it leads to deference an uninitialized pointer to the matching element. Make sure element data area and stateful expression are accessed if there is a matching set element. This patch undoes24791b9aa1
("netfilter: nft_set_bitmap: initialize set element extension in lookups") which is not required anymore. Fixes:339706bc21
("netfilter: nft_lookup: update element stateful expression") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
314 lines
8.6 KiB
C
314 lines
8.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2017 Pablo Neira Ayuso <pablo@netfilter.org>
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/list.h>
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#include <linux/netlink.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables_core.h>
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struct nft_bitmap_elem {
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struct list_head head;
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struct nft_set_ext ext;
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};
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/* This bitmap uses two bits to represent one element. These two bits determine
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* the element state in the current and the future generation.
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*
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* An element can be in three states. The generation cursor is represented using
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* the ^ character, note that this cursor shifts on every succesful transaction.
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* If no transaction is going on, we observe all elements are in the following
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* state:
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*
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* 11 = this element is active in the current generation. In case of no updates,
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* ^ it stays active in the next generation.
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* 00 = this element is inactive in the current generation. In case of no
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* ^ updates, it stays inactive in the next generation.
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*
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* On transaction handling, we observe these two temporary states:
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*
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* 01 = this element is inactive in the current generation and it becomes active
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* ^ in the next one. This happens when the element is inserted but commit
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* path has not yet been executed yet, so activation is still pending. On
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* transaction abortion, the element is removed.
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* 10 = this element is active in the current generation and it becomes inactive
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* ^ in the next one. This happens when the element is deactivated but commit
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* path has not yet been executed yet, so removal is still pending. On
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* transation abortion, the next generation bit is reset to go back to
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* restore its previous state.
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*/
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struct nft_bitmap {
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struct list_head list;
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u16 bitmap_size;
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u8 bitmap[];
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};
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static inline void nft_bitmap_location(const struct nft_set *set,
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const void *key,
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u32 *idx, u32 *off)
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{
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u32 k;
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if (set->klen == 2)
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k = *(u16 *)key;
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else
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k = *(u8 *)key;
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k <<= 1;
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*idx = k / BITS_PER_BYTE;
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*off = k % BITS_PER_BYTE;
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}
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/* Fetch the two bits that represent the element and check if it is active based
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* on the generation mask.
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*/
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static inline bool
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nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask)
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{
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return (bitmap[idx] & (0x3 << off)) & (genmask << off);
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}
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static bool nft_bitmap_lookup(const struct net *net, const struct nft_set *set,
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const u32 *key, const struct nft_set_ext **ext)
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{
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const struct nft_bitmap *priv = nft_set_priv(set);
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u8 genmask = nft_genmask_cur(net);
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u32 idx, off;
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nft_bitmap_location(set, key, &idx, &off);
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return nft_bitmap_active(priv->bitmap, idx, off, genmask);
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}
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static struct nft_bitmap_elem *
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nft_bitmap_elem_find(const struct nft_set *set, struct nft_bitmap_elem *this,
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u8 genmask)
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{
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const struct nft_bitmap *priv = nft_set_priv(set);
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struct nft_bitmap_elem *be;
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list_for_each_entry_rcu(be, &priv->list, head) {
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if (memcmp(nft_set_ext_key(&be->ext),
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nft_set_ext_key(&this->ext), set->klen) ||
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!nft_set_elem_active(&be->ext, genmask))
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continue;
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return be;
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}
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return NULL;
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}
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static void *nft_bitmap_get(const struct net *net, const struct nft_set *set,
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const struct nft_set_elem *elem, unsigned int flags)
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{
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const struct nft_bitmap *priv = nft_set_priv(set);
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u8 genmask = nft_genmask_cur(net);
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struct nft_bitmap_elem *be;
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list_for_each_entry_rcu(be, &priv->list, head) {
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if (memcmp(nft_set_ext_key(&be->ext), elem->key.val.data, set->klen) ||
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!nft_set_elem_active(&be->ext, genmask))
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continue;
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return be;
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}
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return ERR_PTR(-ENOENT);
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}
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static int nft_bitmap_insert(const struct net *net, const struct nft_set *set,
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const struct nft_set_elem *elem,
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struct nft_set_ext **ext)
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{
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struct nft_bitmap *priv = nft_set_priv(set);
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struct nft_bitmap_elem *new = elem->priv, *be;
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u8 genmask = nft_genmask_next(net);
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u32 idx, off;
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be = nft_bitmap_elem_find(set, new, genmask);
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if (be) {
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*ext = &be->ext;
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return -EEXIST;
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}
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nft_bitmap_location(set, nft_set_ext_key(&new->ext), &idx, &off);
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/* Enter 01 state. */
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priv->bitmap[idx] |= (genmask << off);
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list_add_tail_rcu(&new->head, &priv->list);
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return 0;
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}
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static void nft_bitmap_remove(const struct net *net,
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const struct nft_set *set,
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const struct nft_set_elem *elem)
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{
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struct nft_bitmap *priv = nft_set_priv(set);
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struct nft_bitmap_elem *be = elem->priv;
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u8 genmask = nft_genmask_next(net);
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u32 idx, off;
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nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
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/* Enter 00 state. */
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priv->bitmap[idx] &= ~(genmask << off);
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list_del_rcu(&be->head);
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}
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static void nft_bitmap_activate(const struct net *net,
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const struct nft_set *set,
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const struct nft_set_elem *elem)
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{
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struct nft_bitmap *priv = nft_set_priv(set);
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struct nft_bitmap_elem *be = elem->priv;
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u8 genmask = nft_genmask_next(net);
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u32 idx, off;
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nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
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/* Enter 11 state. */
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priv->bitmap[idx] |= (genmask << off);
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nft_set_elem_change_active(net, set, &be->ext);
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}
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static bool nft_bitmap_flush(const struct net *net,
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const struct nft_set *set, void *_be)
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{
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struct nft_bitmap *priv = nft_set_priv(set);
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u8 genmask = nft_genmask_next(net);
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struct nft_bitmap_elem *be = _be;
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u32 idx, off;
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nft_bitmap_location(set, nft_set_ext_key(&be->ext), &idx, &off);
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/* Enter 10 state, similar to deactivation. */
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priv->bitmap[idx] &= ~(genmask << off);
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nft_set_elem_change_active(net, set, &be->ext);
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return true;
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}
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static void *nft_bitmap_deactivate(const struct net *net,
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const struct nft_set *set,
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const struct nft_set_elem *elem)
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{
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struct nft_bitmap *priv = nft_set_priv(set);
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struct nft_bitmap_elem *this = elem->priv, *be;
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u8 genmask = nft_genmask_next(net);
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u32 idx, off;
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nft_bitmap_location(set, elem->key.val.data, &idx, &off);
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be = nft_bitmap_elem_find(set, this, genmask);
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if (!be)
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return NULL;
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/* Enter 10 state. */
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priv->bitmap[idx] &= ~(genmask << off);
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nft_set_elem_change_active(net, set, &be->ext);
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return be;
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}
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static void nft_bitmap_walk(const struct nft_ctx *ctx,
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struct nft_set *set,
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struct nft_set_iter *iter)
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{
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const struct nft_bitmap *priv = nft_set_priv(set);
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struct nft_bitmap_elem *be;
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struct nft_set_elem elem;
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list_for_each_entry_rcu(be, &priv->list, head) {
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if (iter->count < iter->skip)
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goto cont;
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if (!nft_set_elem_active(&be->ext, iter->genmask))
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goto cont;
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elem.priv = be;
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iter->err = iter->fn(ctx, set, iter, &elem);
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if (iter->err < 0)
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return;
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cont:
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iter->count++;
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}
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}
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/* The bitmap size is pow(2, key length in bits) / bits per byte. This is
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* multiplied by two since each element takes two bits. For 8 bit keys, the
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* bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes.
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*/
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static inline u32 nft_bitmap_size(u32 klen)
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{
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return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1;
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}
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static inline u64 nft_bitmap_total_size(u32 klen)
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{
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return sizeof(struct nft_bitmap) + nft_bitmap_size(klen);
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}
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static u64 nft_bitmap_privsize(const struct nlattr * const nla[],
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const struct nft_set_desc *desc)
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{
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u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN]));
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return nft_bitmap_total_size(klen);
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}
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static int nft_bitmap_init(const struct nft_set *set,
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const struct nft_set_desc *desc,
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const struct nlattr * const nla[])
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{
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struct nft_bitmap *priv = nft_set_priv(set);
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INIT_LIST_HEAD(&priv->list);
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priv->bitmap_size = nft_bitmap_size(set->klen);
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return 0;
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}
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static void nft_bitmap_destroy(const struct nft_set *set)
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{
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struct nft_bitmap *priv = nft_set_priv(set);
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struct nft_bitmap_elem *be, *n;
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list_for_each_entry_safe(be, n, &priv->list, head)
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nft_set_elem_destroy(set, be, true);
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}
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static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
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struct nft_set_estimate *est)
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{
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/* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
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if (desc->klen > 2)
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return false;
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else if (desc->expr)
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return false;
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est->size = nft_bitmap_total_size(desc->klen);
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est->lookup = NFT_SET_CLASS_O_1;
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est->space = NFT_SET_CLASS_O_1;
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return true;
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}
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const struct nft_set_type nft_set_bitmap_type = {
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.ops = {
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.privsize = nft_bitmap_privsize,
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.elemsize = offsetof(struct nft_bitmap_elem, ext),
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.estimate = nft_bitmap_estimate,
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.init = nft_bitmap_init,
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.destroy = nft_bitmap_destroy,
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.insert = nft_bitmap_insert,
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.remove = nft_bitmap_remove,
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.deactivate = nft_bitmap_deactivate,
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.flush = nft_bitmap_flush,
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.activate = nft_bitmap_activate,
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.lookup = nft_bitmap_lookup,
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.walk = nft_bitmap_walk,
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.get = nft_bitmap_get,
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},
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};
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