netfilter: nf_tables: report use refcount overflow

Overflow use refcount checks are not complete.

Add helper function to deal with object reference counter tracking.
Report -EMFILE in case UINT_MAX is reached.

nft_use_dec() splats in case that reference counter underflows,
which should not ever happen.

Add nft_use_inc_restore() and nft_use_dec_restore() which are used
to restore reference counter from error and abort paths.

Use u32 in nft_flowtable and nft_object since helper functions cannot
work on bitfields.

Remove the few early incomplete checks now that the helper functions
are in place and used to check for refcount overflow.

Fixes: 96518518cc41 ("netfilter: add nftables")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

4 files changed, 114 insertions, 71 deletions

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 9573a8fcad79..86b3c4de7f40 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -253,8 +253,10 @@ int nf_tables_bind_chain(const struct nft_ctx *ctx, struct nft_chain *chain)
 	if (chain->bound)
 		return -EBUSY;
 
+	if (!nft_use_inc(&chain->use))
+		return -EMFILE;
+
 	chain->bound = true;
-	chain->use++;
 	nft_chain_trans_bind(ctx, chain);
 
 	return 0;
@@ -437,7 +439,7 @@ static int nft_delchain(struct nft_ctx *ctx)
 	if (IS_ERR(trans))
 		return PTR_ERR(trans);
 
-	ctx->table->use--;
+	nft_use_dec(&ctx->table->use);
 	nft_deactivate_next(ctx->net, ctx->chain);
 
 	return 0;
@@ -476,7 +478,7 @@ nf_tables_delrule_deactivate(struct nft_ctx *ctx, struct nft_rule *rule)
 	/* You cannot delete the same rule twice */
 	if (nft_is_active_next(ctx->net, rule)) {
 		nft_deactivate_next(ctx->net, rule);
-		ctx->chain->use--;
+		nft_use_dec(&ctx->chain->use);
 		return 0;
 	}
 	return -ENOENT;
@@ -644,7 +646,7 @@ static int nft_delset(const struct nft_ctx *ctx, struct nft_set *set)
 		nft_map_deactivate(ctx, set);
 
 	nft_deactivate_next(ctx->net, set);
-	ctx->table->use--;
+	nft_use_dec(&ctx->table->use);
 
 	return err;
 }
@@ -676,7 +678,7 @@ static int nft_delobj(struct nft_ctx *ctx, struct nft_object *obj)
 		return err;
 
 	nft_deactivate_next(ctx->net, obj);
-	ctx->table->use--;
+	nft_use_dec(&ctx->table->use);
 
 	return err;
 }
@@ -711,7 +713,7 @@ static int nft_delflowtable(struct nft_ctx *ctx,
 		return err;
 
 	nft_deactivate_next(ctx->net, flowtable);
-	ctx->table->use--;
+	nft_use_dec(&ctx->table->use);
 
 	return err;
 }
@@ -2396,9 +2398,6 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 	struct nft_chain *chain;
 	int err;
 
-	if (table->use == UINT_MAX)
-		return -EOVERFLOW;
-
 	if (nla[NFTA_CHAIN_HOOK]) {
 		struct nft_stats __percpu *stats = NULL;
 		struct nft_chain_hook hook = {};
@@ -2494,6 +2493,11 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 	if (err < 0)
 		goto err_destroy_chain;
 
+	if (!nft_use_inc(&table->use)) {
+		err = -EMFILE;
+		goto err_use;
+	}
+
 	trans = nft_trans_chain_add(ctx, NFT_MSG_NEWCHAIN);
 	if (IS_ERR(trans)) {
 		err = PTR_ERR(trans);
@@ -2510,10 +2514,11 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 		goto err_unregister_hook;
 	}
 
-	table->use++;
-
 	return 0;
+
 err_unregister_hook:
+	nft_use_dec_restore(&table->use);
+err_use:
 	nf_tables_unregister_hook(net, table, chain);
 err_destroy_chain:
 	nf_tables_chain_destroy(ctx);
@@ -3840,9 +3845,6 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 			return -EINVAL;
 		handle = nf_tables_alloc_handle(table);
 
-		if (chain->use == UINT_MAX)
-			return -EOVERFLOW;
-
 		if (nla[NFTA_RULE_POSITION]) {
 			pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
 			old_rule = __nft_rule_lookup(chain, pos_handle);
@@ -3936,6 +3938,11 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 		}
 	}
 
+	if (!nft_use_inc(&chain->use)) {
+		err = -EMFILE;
+		goto err_release_rule;
+	}
+
 	if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
 		err = nft_delrule(&ctx, old_rule);
 		if (err < 0)
@@ -3967,7 +3974,6 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 		}
 	}
 	kvfree(expr_info);
-	chain->use++;
 
 	if (flow)
 		nft_trans_flow_rule(trans) = flow;
@@ -3978,6 +3984,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 	return 0;
 
 err_destroy_flow_rule:
+	nft_use_dec_restore(&chain->use);
 	if (flow)
 		nft_flow_rule_destroy(flow);
 err_release_rule:
@@ -5014,9 +5021,15 @@ static int nf_tables_newset(struct sk_buff *skb, const struct nfnl_info *info,
 	alloc_size = sizeof(*set) + size + udlen;
 	if (alloc_size < size || alloc_size > INT_MAX)
 		return -ENOMEM;
+
+	if (!nft_use_inc(&table->use))
+		return -EMFILE;
+
 	set = kvzalloc(alloc_size, GFP_KERNEL_ACCOUNT);
-	if (!set)
-		return -ENOMEM;
+	if (!set) {
+		err = -ENOMEM;
+		goto err_alloc;
+	}
 
 	name = nla_strdup(nla[NFTA_SET_NAME], GFP_KERNEL_ACCOUNT);
 	if (!name) {
@@ -5074,7 +5087,7 @@ static int nf_tables_newset(struct sk_buff *skb, const struct nfnl_info *info,
 		goto err_set_expr_alloc;
 
 	list_add_tail_rcu(&set->list, &table->sets);
-	table->use++;
+
 	return 0;
 
 err_set_expr_alloc:
@@ -5086,6 +5099,9 @@ err_set_init:
 	kfree(set->name);
 err_set_name:
 	kvfree(set);
+err_alloc:
+	nft_use_dec_restore(&table->use);
+
 	return err;
 }
 
@@ -5224,9 +5240,6 @@ int nf_tables_bind_set(const struct nft_ctx *ctx, struct nft_set *set,
 	struct nft_set_binding *i;
 	struct nft_set_iter iter;
 
-	if (set->use == UINT_MAX)
-		return -EOVERFLOW;
-
 	if (!list_empty(&set->bindings) && nft_set_is_anonymous(set))
 		return -EBUSY;
 
@@ -5254,10 +5267,12 @@ int nf_tables_bind_set(const struct nft_ctx *ctx, struct nft_set *set,
 			return iter.err;
 	}
 bind:
+	if (!nft_use_inc(&set->use))
+		return -EMFILE;
+
 	binding->chain = ctx->chain;
 	list_add_tail_rcu(&binding->list, &set->bindings);
 	nft_set_trans_bind(ctx, set);
-	set->use++;
 
 	return 0;
 }
@@ -5331,7 +5346,7 @@ void nf_tables_activate_set(const struct nft_ctx *ctx, struct nft_set *set)
 		nft_clear(ctx->net, set);
 	}
 
-	set->use++;
+	nft_use_inc_restore(&set->use);
 }
 EXPORT_SYMBOL_GPL(nf_tables_activate_set);
 
@@ -5347,7 +5362,7 @@ void nf_tables_deactivate_set(const struct nft_ctx *ctx, struct nft_set *set,
 		else
 			list_del_rcu(&binding->list);
 
-		set->use--;
+		nft_use_dec(&set->use);
 		break;
 	case NFT_TRANS_PREPARE:
 		if (nft_set_is_anonymous(set)) {
@@ -5356,7 +5371,7 @@ void nf_tables_deactivate_set(const struct nft_ctx *ctx, struct nft_set *set,
 
 			nft_deactivate_next(ctx->net, set);
 		}
-		set->use--;
+		nft_use_dec(&set->use);
 		return;
 	case NFT_TRANS_ABORT:
 	case NFT_TRANS_RELEASE:
@@ -5364,7 +5379,7 @@ void nf_tables_deactivate_set(const struct nft_ctx *ctx, struct nft_set *set,
 		    set->flags & (NFT_SET_MAP | NFT_SET_OBJECT))
 			nft_map_deactivate(ctx, set);
 
-		set->use--;
+		nft_use_dec(&set->use);
 		fallthrough;
 	default:
 		nf_tables_unbind_set(ctx, set, binding,
@@ -6155,7 +6170,7 @@ void nft_set_elem_destroy(const struct nft_set *set, void *elem,
 		nft_set_elem_expr_destroy(&ctx, nft_set_ext_expr(ext));
 
 	if (nft_set_ext_exists(ext, NFT_SET_EXT_OBJREF))
-		(*nft_set_ext_obj(ext))->use--;
+		nft_use_dec(&(*nft_set_ext_obj(ext))->use);
 	kfree(elem);
 }
 EXPORT_SYMBOL_GPL(nft_set_elem_destroy);
@@ -6657,8 +6672,16 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
 				     set->objtype, genmask);
 		if (IS_ERR(obj)) {
 			err = PTR_ERR(obj);
+			obj = NULL;
 			goto err_parse_key_end;
 		}
+
+		if (!nft_use_inc(&obj->use)) {
+			err = -EMFILE;
+			obj = NULL;
+			goto err_parse_key_end;
+		}
+
 		err = nft_set_ext_add(&tmpl, NFT_SET_EXT_OBJREF);
 		if (err < 0)
 			goto err_parse_key_end;
@@ -6727,10 +6750,9 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
 	if (flags)
 		*nft_set_ext_flags(ext) = flags;
 
-	if (obj) {
+	if (obj)
 		*nft_set_ext_obj(ext) = obj;
-		obj->use++;
-	}
+
 	if (ulen > 0) {
 		if (nft_set_ext_check(&tmpl, NFT_SET_EXT_USERDATA, ulen) < 0) {
 			err = -EINVAL;
@@ -6798,12 +6820,13 @@ err_element_clash:
 	kfree(trans);
 err_elem_free:
 	nf_tables_set_elem_destroy(ctx, set, elem.priv);
-	if (obj)
-		obj->use--;
 err_parse_data:
 	if (nla[NFTA_SET_ELEM_DATA] != NULL)
 		nft_data_release(&elem.data.val, desc.type);
 err_parse_key_end:
+	if (obj)
+		nft_use_dec_restore(&obj->use);
+
 	nft_data_release(&elem.key_end.val, NFT_DATA_VALUE);
 err_parse_key:
 	nft_data_release(&elem.key.val, NFT_DATA_VALUE);
@@ -6883,7 +6906,7 @@ void nft_data_hold(const struct nft_data *data, enum nft_data_types type)
 		case NFT_JUMP:
 		case NFT_GOTO:
 			chain = data->verdict.chain;
-			chain->use++;
+			nft_use_inc_restore(&chain->use);
 			break;
 		}
 	}
@@ -6898,7 +6921,7 @@ static void nft_setelem_data_activate(const struct net *net,
 	if (nft_set_ext_exists(ext, NFT_SET_EXT_DATA))
 		nft_data_hold(nft_set_ext_data(ext), set->dtype);
 	if (nft_set_ext_exists(ext, NFT_SET_EXT_OBJREF))
-		(*nft_set_ext_obj(ext))->use++;
+		nft_use_inc_restore(&(*nft_set_ext_obj(ext))->use);
 }
 
 static void nft_setelem_data_deactivate(const struct net *net,
@@ -6910,7 +6933,7 @@ static void nft_setelem_data_deactivate(const struct net *net,
 	if (nft_set_ext_exists(ext, NFT_SET_EXT_DATA))
 		nft_data_release(nft_set_ext_data(ext), set->dtype);
 	if (nft_set_ext_exists(ext, NFT_SET_EXT_OBJREF))
-		(*nft_set_ext_obj(ext))->use--;
+		nft_use_dec(&(*nft_set_ext_obj(ext))->use);
 }
 
 static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,
@@ -7453,9 +7476,14 @@ static int nf_tables_newobj(struct sk_buff *skb, const struct nfnl_info *info,
 
 	nft_ctx_init(&ctx, net, skb, info->nlh, family, table, NULL, nla);
 
+	if (!nft_use_inc(&table->use))
+		return -EMFILE;
+
 	type = nft_obj_type_get(net, objtype);
-	if (IS_ERR(type))
-		return PTR_ERR(type);
+	if (IS_ERR(type)) {
+		err = PTR_ERR(type);
+		goto err_type;
+	}
 
 	obj = nft_obj_init(&ctx, type, nla[NFTA_OBJ_DATA]);
 	if (IS_ERR(obj)) {
@@ -7489,7 +7517,7 @@ static int nf_tables_newobj(struct sk_buff *skb, const struct nfnl_info *info,
 		goto err_obj_ht;
 
 	list_add_tail_rcu(&obj->list, &table->objects);
-	table->use++;
+
 	return 0;
 err_obj_ht:
 	/* queued in transaction log */
@@ -7505,6 +7533,9 @@ err_strdup:
 	kfree(obj);
 err_init:
 	module_put(type->owner);
+err_type:
+	nft_use_dec_restore(&table->use);
+
 	return err;
 }
 
@@ -7906,7 +7937,7 @@ void nf_tables_deactivate_flowtable(const struct nft_ctx *ctx,
 	case NFT_TRANS_PREPARE:
 	case NFT_TRANS_ABORT:
 	case NFT_TRANS_RELEASE:
-		flowtable->use--;
+		nft_use_dec(&flowtable->use);
 		fallthrough;
 	default:
 		return;
@@ -8260,9 +8291,14 @@ static int nf_tables_newflowtable(struct sk_buff *skb,
 
 	nft_ctx_init(&ctx, net, skb, info->nlh, family, table, NULL, nla);
 
+	if (!nft_use_inc(&table->use))
+		return -EMFILE;
+
 	flowtable = kzalloc(sizeof(*flowtable), GFP_KERNEL_ACCOUNT);
-	if (!flowtable)
-		return -ENOMEM;
+	if (!flowtable) {
+		err = -ENOMEM;
+		goto flowtable_alloc;
+	}
 
 	flowtable->table = table;
 	flowtable->handle = nf_tables_alloc_handle(table);
@@ -8317,7 +8353,6 @@ static int nf_tables_newflowtable(struct sk_buff *skb,
 		goto err5;
 
 	list_add_tail_rcu(&flowtable->list, &table->flowtables);
-	table->use++;
 
 	return 0;
 err5:
@@ -8334,6 +8369,9 @@ err2:
 	kfree(flowtable->name);
 err1:
 	kfree(flowtable);
+flowtable_alloc:
+	nft_use_dec_restore(&table->use);
+
 	return err;
 }
 
@@ -9713,7 +9751,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 				 */
 				if (nft_set_is_anonymous(nft_trans_set(trans)) &&
 				    !list_empty(&nft_trans_set(trans)->bindings))
-					trans->ctx.table->use--;
+					nft_use_dec(&trans->ctx.table->use);
 			}
 			nf_tables_set_notify(&trans->ctx, nft_trans_set(trans),
 					     NFT_MSG_NEWSET, GFP_KERNEL);
@@ -9943,7 +9981,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 					nft_trans_destroy(trans);
 					break;
 				}
-				trans->ctx.table->use--;
+				nft_use_dec_restore(&trans->ctx.table->use);
 				nft_chain_del(trans->ctx.chain);
 				nf_tables_unregister_hook(trans->ctx.net,
 							  trans->ctx.table,
@@ -9956,7 +9994,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 				list_splice(&nft_trans_chain_hooks(trans),
 					    &nft_trans_basechain(trans)->hook_list);
 			} else {
-				trans->ctx.table->use++;
+				nft_use_inc_restore(&trans->ctx.table->use);
 				nft_clear(trans->ctx.net, trans->ctx.chain);
 			}
 			nft_trans_destroy(trans);
@@ -9966,7 +10004,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 				nft_trans_destroy(trans);
 				break;
 			}
-			trans->ctx.chain->use--;
+			nft_use_dec_restore(&trans->ctx.chain->use);
 			list_del_rcu(&nft_trans_rule(trans)->list);
 			nft_rule_expr_deactivate(&trans->ctx,
 						 nft_trans_rule(trans),
@@ -9976,7 +10014,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 			break;
 		case NFT_MSG_DELRULE:
 		case NFT_MSG_DESTROYRULE:
-			trans->ctx.chain->use++;
+			nft_use_inc_restore(&trans->ctx.chain->use);
 			nft_clear(trans->ctx.net, nft_trans_rule(trans));
 			nft_rule_expr_activate(&trans->ctx, nft_trans_rule(trans));
 			if (trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD)
@@ -9989,7 +10027,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 				nft_trans_destroy(trans);
 				break;
 			}
-			trans->ctx.table->use--;
+			nft_use_dec_restore(&trans->ctx.table->use);
 			if (nft_trans_set_bound(trans)) {
 				nft_trans_destroy(trans);
 				break;
@@ -9998,7 +10036,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 			break;
 		case NFT_MSG_DELSET:
 		case NFT_MSG_DESTROYSET:
-			trans->ctx.table->use++;
+			nft_use_inc_restore(&trans->ctx.table->use);
 			nft_clear(trans->ctx.net, nft_trans_set(trans));
 			if (nft_trans_set(trans)->flags & (NFT_SET_MAP | NFT_SET_OBJECT))
 				nft_map_activate(&trans->ctx, nft_trans_set(trans));
@@ -10042,13 +10080,13 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 				nft_obj_destroy(&trans->ctx, nft_trans_obj_newobj(trans));
 				nft_trans_destroy(trans);
 			} else {
-				trans->ctx.table->use--;
+				nft_use_dec_restore(&trans->ctx.table->use);
 				nft_obj_del(nft_trans_obj(trans));
 			}
 			break;
 		case NFT_MSG_DELOBJ:
 		case NFT_MSG_DESTROYOBJ:
-			trans->ctx.table->use++;
+			nft_use_inc_restore(&trans->ctx.table->use);
 			nft_clear(trans->ctx.net, nft_trans_obj(trans));
 			nft_trans_destroy(trans);
 			break;
@@ -10057,7 +10095,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 				nft_unregister_flowtable_net_hooks(net,
 						&nft_trans_flowtable_hooks(trans));
 			} else {
-				trans->ctx.table->use--;
+				nft_use_dec_restore(&trans->ctx.table->use);
 				list_del_rcu(&nft_trans_flowtable(trans)->list);
 				nft_unregister_flowtable_net_hooks(net,
 						&nft_trans_flowtable(trans)->hook_list);
@@ -10069,7 +10107,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 				list_splice(&nft_trans_flowtable_hooks(trans),
 					    &nft_trans_flowtable(trans)->hook_list);
 			} else {
-				trans->ctx.table->use++;
+				nft_use_inc_restore(&trans->ctx.table->use);
 				nft_clear(trans->ctx.net, nft_trans_flowtable(trans));
 			}
 			nft_trans_destroy(trans);
@@ -10518,8 +10556,9 @@ static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data,
 		if (desc->flags & NFT_DATA_DESC_SETELEM &&
 		    chain->flags & NFT_CHAIN_BINDING)
 			return -EINVAL;
+		if (!nft_use_inc(&chain->use))
+			return -EMFILE;
 
-		chain->use++;
 		data->verdict.chain = chain;
 		break;
 	}
@@ -10537,7 +10576,7 @@ static void nft_verdict_uninit(const struct nft_data *data)
 	case NFT_JUMP:
 	case NFT_GOTO:
 		chain = data->verdict.chain;
-		chain->use--;
+		nft_use_dec(&chain->use);
 		break;
 	}
 }
@@ -10706,11 +10745,11 @@ int __nft_release_basechain(struct nft_ctx *ctx)
 	nf_tables_unregister_hook(ctx->net, ctx->chain->table, ctx->chain);
 	list_for_each_entry_safe(rule, nr, &ctx->chain->rules, list) {
 		list_del(&rule->list);
-		ctx->chain->use--;
+		nft_use_dec(&ctx->chain->use);
 		nf_tables_rule_release(ctx, rule);
 	}
 	nft_chain_del(ctx->chain);
-	ctx->table->use--;
+	nft_use_dec(&ctx->table->use);
 	nf_tables_chain_destroy(ctx);
 
 	return 0;
@@ -10760,18 +10799,18 @@ static void __nft_release_table(struct net *net, struct nft_table *table)
 		ctx.chain = chain;
 		list_for_each_entry_safe(rule, nr, &chain->rules, list) {
 			list_del(&rule->list);
-			chain->use--;
+			nft_use_dec(&chain->use);
 			nf_tables_rule_release(&ctx, rule);
 		}
 	}
 	list_for_each_entry_safe(flowtable, nf, &table->flowtables, list) {
 		list_del(&flowtable->list);
-		table->use--;
+		nft_use_dec(&table->use);
 		nf_tables_flowtable_destroy(flowtable);
 	}
 	list_for_each_entry_safe(set, ns, &table->sets, list) {
 		list_del(&set->list);
-		table->use--;
+		nft_use_dec(&table->use);
 		if (set->flags & (NFT_SET_MAP | NFT_SET_OBJECT))
 			nft_map_deactivate(&ctx, set);
 
@@ -10779,13 +10818,13 @@ static void __nft_release_table(struct net *net, struct nft_table *table)
 	}
 	list_for_each_entry_safe(obj, ne, &table->objects, list) {
 		nft_obj_del(obj);
-		table->use--;
+		nft_use_dec(&table->use);
 		nft_obj_destroy(&ctx, obj);
 	}
 	list_for_each_entry_safe(chain, nc, &table->chains, list) {
 		ctx.chain = chain;
 		nft_chain_del(chain);
-		table->use--;
+		nft_use_dec(&table->use);
 		nf_tables_chain_destroy(&ctx);
 	}
 	nf_tables_table_destroy(&ctx);
diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
index 5ef9146e74ad..ab3362c483b4 100644
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -408,8 +408,10 @@ static int nft_flow_offload_init(const struct nft_ctx *ctx,
 	if (IS_ERR(flowtable))
 		return PTR_ERR(flowtable);
 
+	if (!nft_use_inc(&flowtable->use))
+		return -EMFILE;
+
 	priv->flowtable = flowtable;
-	flowtable->use++;
 
 	return nf_ct_netns_get(ctx->net, ctx->family);
 }
@@ -428,7 +430,7 @@ static void nft_flow_offload_activate(const struct nft_ctx *ctx,
 {
 	struct nft_flow_offload *priv = nft_expr_priv(expr);
 
-	priv->flowtable->use++;
+	nft_use_inc_restore(&priv->flowtable->use);
 }
 
 static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
diff --git a/net/netfilter/nft_immediate.c b/net/netfilter/nft_immediate.c
index 3d76ebfe8939..407d7197f75b 100644
--- a/net/netfilter/nft_immediate.c
+++ b/net/netfilter/nft_immediate.c
@@ -159,7 +159,7 @@ static void nft_immediate_deactivate(const struct nft_ctx *ctx,
 			default:
 				nft_chain_del(chain);
 				chain->bound = false;
-				chain->table->use--;
+				nft_use_dec(&chain->table->use);
 				break;
 			}
 			break;
@@ -198,7 +198,7 @@ static void nft_immediate_destroy(const struct nft_ctx *ctx,
 		 * let the transaction records release this chain and its rules.
 		 */
 		if (chain->bound) {
-			chain->use--;
+			nft_use_dec(&chain->use);
 			break;
 		}
 
@@ -206,9 +206,9 @@ static void nft_immediate_destroy(const struct nft_ctx *ctx,
 		chain_ctx = *ctx;
 		chain_ctx.chain = chain;
 
-		chain->use--;
+		nft_use_dec(&chain->use);
 		list_for_each_entry_safe(rule, n, &chain->rules, list) {
-			chain->use--;
+			nft_use_dec(&chain->use);
 			list_del(&rule->list);
 			nf_tables_rule_destroy(&chain_ctx, rule);
 		}
diff --git a/net/netfilter/nft_objref.c b/net/netfilter/nft_objref.c
index a48dd5b5d45b..509011b1ef59 100644
--- a/net/netfilter/nft_objref.c
+++ b/net/netfilter/nft_objref.c
@@ -41,8 +41,10 @@ static int nft_objref_init(const struct nft_ctx *ctx,
 	if (IS_ERR(obj))
 		return -ENOENT;
 
+	if (!nft_use_inc(&obj->use))
+		return -EMFILE;
+
 	nft_objref_priv(expr) = obj;
-	obj->use++;
 
 	return 0;
 }
@@ -72,7 +74,7 @@ static void nft_objref_deactivate(const struct nft_ctx *ctx,
 	if (phase == NFT_TRANS_COMMIT)
 		return;
 
-	obj->use--;
+	nft_use_dec(&obj->use);
 }
 
 static void nft_objref_activate(const struct nft_ctx *ctx,
@@ -80,7 +82,7 @@ static void nft_objref_activate(const struct nft_ctx *ctx,
 {
 	struct nft_object *obj = nft_objref_priv(expr);
 
-	obj->use++;
+	nft_use_inc_restore(&obj->use);
 }
 
 static const struct nft_expr_ops nft_objref_ops = {