netfilter: nf_tables: add destroy_clone expression

Before this patch, cloned expressions are released via ->destroy. This
is a problem for the new connlimit expression since the ->destroy path
drop a reference on the conntrack modules and it unregisters hooks. The
new ->destroy_clone provides context that this expression is being
released from the packet path, so it is mirroring ->clone(), where
neither module reference is dropped nor hooks need to be unregistered -
because this done from the control plane path from the ->init() path.

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

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 871cb3b..83e7b83 100644 (file)
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -745,6 +745,8 @@ struct nft_expr_ops {
                                                      const struct nft_expr *expr);
        void                            (*destroy)(const struct nft_ctx *ctx,
                                                   const struct nft_expr *expr);
+       void                            (*destroy_clone)(const struct nft_ctx *ctx,
+                                                        const struct nft_expr *expr);
        int                             (*dump)(struct sk_buff *skb,
                                                const struct nft_expr *expr);
        int                             (*validate)(const struct nft_ctx *ctx,

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 1246398..0a6eafa 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -4046,8 +4046,16 @@ void nft_set_elem_destroy(const struct nft_set *set, void *elem,
        nft_data_release(nft_set_ext_key(ext), NFT_DATA_VALUE);
        if (nft_set_ext_exists(ext, NFT_SET_EXT_DATA))
                nft_data_release(nft_set_ext_data(ext), set->dtype);
-       if (destroy_expr && nft_set_ext_exists(ext, NFT_SET_EXT_EXPR))
-               nf_tables_expr_destroy(&ctx, nft_set_ext_expr(ext));
+       if (destroy_expr && nft_set_ext_exists(ext, NFT_SET_EXT_EXPR)) {
+               struct nft_expr *expr = nft_set_ext_expr(ext);
+
+               if (expr->ops->destroy_clone) {
+                       expr->ops->destroy_clone(&ctx, expr);
+                       module_put(expr->ops->type->owner);
+               } else {
+                       nf_tables_expr_destroy(&ctx, expr);
+               }
+       }
        if (nft_set_ext_exists(ext, NFT_SET_EXT_OBJREF))
                (*nft_set_ext_obj(ext))->use--;
        kfree(elem);

diff --git a/net/netfilter/nft_counter.c b/net/netfilter/nft_counter.c
index e59a74d..a61d7ed 100644 (file)
--- a/net/netfilter/nft_counter.c
+++ b/net/netfilter/nft_counter.c
@@ -258,6 +258,7 @@ static const struct nft_expr_ops nft_counter_ops = {
        .eval           = nft_counter_eval,
        .init           = nft_counter_init,
        .destroy        = nft_counter_destroy,
+       .destroy_clone  = nft_counter_destroy,
        .dump           = nft_counter_dump,
        .clone          = nft_counter_clone,
 };