netfilter: nf_tables: remove busy mark and gc batch API

jira VULN-430
cve CVE-2023-4244
commit-author Pablo Neira Ayuso <[email protected]>
commit a2dd023

Ditch it, it has been replace it by the GC transaction API and it has no
clients anymore.

	Signed-off-by: Pablo Neira Ayuso <[email protected]>
(cherry picked from commit a2dd023)
	Signed-off-by: Marcin Wcisło <[email protected]>

Author: pvts-mat

include/net/netfilter/nf_tables.h

@@ -562,7 +562,6 @@ struct nft_set *nft_set_lookup_global(const struct net *net,
 
 struct nft_set_ext *nft_set_catchall_lookup(const struct net *net,
 					    const struct nft_set *set);
-void *nft_set_catchall_gc(const struct nft_set *set);
 
 static inline unsigned long nft_set_gc_interval(const struct nft_set *set)
 {
@@ -779,62 +778,6 @@ void nft_set_elem_destroy(const struct nft_set *set, void *elem,
 void nf_tables_set_elem_destroy(const struct nft_ctx *ctx,
 				const struct nft_set *set, void *elem);
 
-/**
- *	struct nft_set_gc_batch_head - nf_tables set garbage collection batch
- *
- *	@rcu: rcu head
- *	@set: set the elements belong to
- *	@cnt: count of elements
- */
-struct nft_set_gc_batch_head {
-	struct rcu_head			rcu;
-	const struct nft_set		*set;
-	unsigned int			cnt;
-};
-
-#define NFT_SET_GC_BATCH_SIZE	((PAGE_SIZE -				  \
-				  sizeof(struct nft_set_gc_batch_head)) / \
-				 sizeof(void *))
-
-/**
- *	struct nft_set_gc_batch - nf_tables set garbage collection batch
- *
- * 	@head: GC batch head
- * 	@elems: garbage collection elements
- */
-struct nft_set_gc_batch {
-	struct nft_set_gc_batch_head	head;
-	void				*elems[NFT_SET_GC_BATCH_SIZE];
-};
-
-struct nft_set_gc_batch *nft_set_gc_batch_alloc(const struct nft_set *set,
-						gfp_t gfp);
-void nft_set_gc_batch_release(struct rcu_head *rcu);
-
-static inline void nft_set_gc_batch_complete(struct nft_set_gc_batch *gcb)
-{
-	if (gcb != NULL)
-		call_rcu(&gcb->head.rcu, nft_set_gc_batch_release);
-}
-
-static inline struct nft_set_gc_batch *
-nft_set_gc_batch_check(const struct nft_set *set, struct nft_set_gc_batch *gcb,
-		       gfp_t gfp)
-{
-	if (gcb != NULL) {
-		if (gcb->head.cnt + 1 < ARRAY_SIZE(gcb->elems))
-			return gcb;
-		nft_set_gc_batch_complete(gcb);
-	}
-	return nft_set_gc_batch_alloc(set, gfp);
-}
-
-static inline void nft_set_gc_batch_add(struct nft_set_gc_batch *gcb,
-					void *elem)
-{
-	gcb->elems[gcb->head.cnt++] = elem;
-}
-
 struct nft_expr_ops;
 /**
  *	struct nft_expr_type - nf_tables expression type
@@ -1498,47 +1441,12 @@ static inline void nft_set_elem_change_active(const struct net *net,
 
 #endif /* IS_ENABLED(CONFIG_NF_TABLES) */
 
-/*
- * We use a free bit in the genmask field to indicate the element
- * is busy, meaning it is currently being processed either by
- * the netlink API or GC.
- *
- * Even though the genmask is only a single byte wide, this works
- * because the extension structure if fully constant once initialized,
- * so there are no non-atomic write accesses unless it is already
- * marked busy.
- */
-#define NFT_SET_ELEM_BUSY_MASK	(1 << 2)
-
-#if defined(__LITTLE_ENDIAN_BITFIELD)
-#define NFT_SET_ELEM_BUSY_BIT	2
-#elif defined(__BIG_ENDIAN_BITFIELD)
-#define NFT_SET_ELEM_BUSY_BIT	(BITS_PER_LONG - BITS_PER_BYTE + 2)
-#else
-#error
-#endif
-
-static inline int nft_set_elem_mark_busy(struct nft_set_ext *ext)
-{
-	unsigned long *word = (unsigned long *)ext;
-
-	BUILD_BUG_ON(offsetof(struct nft_set_ext, genmask) != 0);
-	return test_and_set_bit(NFT_SET_ELEM_BUSY_BIT, word);
-}
-
-static inline void nft_set_elem_clear_busy(struct nft_set_ext *ext)
-{
-	unsigned long *word = (unsigned long *)ext;
-
-	clear_bit(NFT_SET_ELEM_BUSY_BIT, word);
-}
-
-#define NFT_SET_ELEM_DEAD_MASK	(1 << 3)
+#define NFT_SET_ELEM_DEAD_MASK	(1 << 2)
 
 #if defined(__LITTLE_ENDIAN_BITFIELD)
-#define NFT_SET_ELEM_DEAD_BIT	3
+#define NFT_SET_ELEM_DEAD_BIT	2
 #elif defined(__BIG_ENDIAN_BITFIELD)
-#define NFT_SET_ELEM_DEAD_BIT	(BITS_PER_LONG - BITS_PER_BYTE + 3)
+#define NFT_SET_ELEM_DEAD_BIT	(BITS_PER_LONG - BITS_PER_BYTE + 2)
 #else
 #error
 #endif

net/netfilter/nf_tables_api.c

@@ -6063,29 +6063,6 @@ struct nft_set_ext *nft_set_catchall_lookup(const struct net *net,
 }
 EXPORT_SYMBOL_GPL(nft_set_catchall_lookup);
 
-void *nft_set_catchall_gc(const struct nft_set *set)
-{
-	struct nft_set_elem_catchall *catchall, *next;
-	struct nft_set_ext *ext;
-	void *elem = NULL;
-
-	list_for_each_entry_safe(catchall, next, &set->catchall_list, list) {
-		ext = nft_set_elem_ext(set, catchall->elem);
-
-		if (!nft_set_elem_expired(ext) ||
-		    nft_set_elem_mark_busy(ext))
-			continue;
-
-		elem = catchall->elem;
-		list_del_rcu(&catchall->list);
-		kfree_rcu(catchall, rcu);
-		break;
-	}
-
-	return elem;
-}
-EXPORT_SYMBOL_GPL(nft_set_catchall_gc);
-
 static int nft_setelem_catchall_insert(const struct net *net,
 				       struct nft_set *set,
 				       const struct nft_set_elem *elem,
@@ -6556,7 +6533,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
 		goto err_elem_free;
 	}
 
-	ext->genmask = nft_genmask_cur(ctx->net) | NFT_SET_ELEM_BUSY_MASK;
+	ext->genmask = nft_genmask_cur(ctx->net);
 
 	err = nft_setelem_insert(ctx->net, set, &elem, &ext2, flags);
 	if (err) {
@@ -6946,29 +6923,6 @@ static int nf_tables_delsetelem(struct sk_buff *skb,
 	return err;
 }
 
-void nft_set_gc_batch_release(struct rcu_head *rcu)
-{
-	struct nft_set_gc_batch *gcb;
-	unsigned int i;
-
-	gcb = container_of(rcu, struct nft_set_gc_batch, head.rcu);
-	for (i = 0; i < gcb->head.cnt; i++)
-		nft_set_elem_destroy(gcb->head.set, gcb->elems[i], true);
-	kfree(gcb);
-}
-
-struct nft_set_gc_batch *nft_set_gc_batch_alloc(const struct nft_set *set,
-						gfp_t gfp)
-{
-	struct nft_set_gc_batch *gcb;
-
-	gcb = kzalloc(sizeof(*gcb), gfp);
-	if (gcb == NULL)
-		return gcb;
-	gcb->head.set = set;
-	return gcb;
-}
-
 /*
  * Stateful objects
  */