netfilter: nft_compat: use .release_ops and remove list of extension

Add .release_ops, that is called in case of error at a later stage in
the expression initialization path, ie. .select_ops() has been already
set up operations and that needs to be undone. This allows us to unwind
.select_ops from the error path, ie. release the dynamic operations for
this extension.

Moreover, allocate one single operation instead of recycling them, this
comes at the cost of consuming a bit more memory per rule, but it
simplifies the infrastructure.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index a66fcd316734..c331e96a713b 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -690,10 +690,12 @@ static inline void nft_set_gc_batch_add(struct nft_set_gc_batch *gcb,
 	gcb->elems[gcb->head.cnt++] = elem;
 }
 
+struct nft_expr_ops;
 /**
  *	struct nft_expr_type - nf_tables expression type
  *
  *	@select_ops: function to select nft_expr_ops
+ *	@release_ops: release nft_expr_ops
  *	@ops: default ops, used when no select_ops functions is present
  *	@list: used internally
  *	@name: Identifier
@@ -706,6 +708,7 @@ static inline void nft_set_gc_batch_add(struct nft_set_gc_batch *gcb,
 struct nft_expr_type {
 	const struct nft_expr_ops	*(*select_ops)(const struct nft_ctx *,
 						       const struct nlattr * const tb[]);
+	void				(*release_ops)(const struct nft_expr_ops *ops);
 	const struct nft_expr_ops	*ops;
 	struct list_head		list;
 	const char			*name;