[PATCH net 07/14] netfilter: nf_tables: fix netdev hook allocation memleak with dormant tables

[Pablo Neira Ayuso <pablo@netfilter.org>]

From: Florian Westphal <fw@strlen.de>

sashiko says:
 could the related code in __nf_tables_abort() leak the struct nft_hook objects when the table is dormant?

 In __nf_tables_abort(), when rolling back a NEWCHAIN transaction that
 updates hooks, the code conditionally unregisters and frees the hooks only
 if the table is not dormant [..]
            if (!(table->flags & NFT_TABLE_F_DORMANT)) {
                nft_netdev_unregister_hooks(net,
                                            &nft_trans_chain_hooks(trans),
                                            true);
            }
            ...
            nft_trans_destroy(trans);

Unfortunately netdev family mixes hook registration and allocation.
Push table struct down and only check for the flag to unregister.

Fixes: 216e7bf7402c ("netfilter: nf_tables: skip netdev hook unregistration if table is dormant")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 38e33c66c618..87387adbca65 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -407,6 +407,7 @@ static void nft_netdev_unregister_trans_hook(struct net *net,
 }
 
 static void nft_netdev_unregister_hooks(struct net *net,
+					const struct nft_table *table,
 					struct list_head *hook_list,
 					bool release_netdev)
 {
@@ -414,8 +415,10 @@ static void nft_netdev_unregister_hooks(struct net *net,
 	struct nf_hook_ops *ops;
 
 	list_for_each_entry_safe(hook, next, hook_list, list) {
-		list_for_each_entry(ops, &hook->ops_list, list)
-			nf_unregister_net_hook(net, ops);
+		if (!(table->flags & NFT_TABLE_F_DORMANT)) {
+			list_for_each_entry(ops, &hook->ops_list, list)
+				nf_unregister_net_hook(net, ops);
+		}
 		if (release_netdev)
 			nft_netdev_hook_unlink_free_rcu(hook);
 	}
@@ -452,20 +455,25 @@ static void __nf_tables_unregister_hook(struct net *net,
 	struct nft_base_chain *basechain;
 	const struct nf_hook_ops *ops;
 
-	if (table->flags & NFT_TABLE_F_DORMANT ||
-	    !nft_is_base_chain(chain))
+	if (!nft_is_base_chain(chain))
 		return;
 	basechain = nft_base_chain(chain);
 	ops = &basechain->ops;
 
+	/* must also be called for dormant tables */
+	if (nft_base_chain_netdev(table->family, basechain->ops.hooknum)) {
+		nft_netdev_unregister_hooks(net, table, &basechain->hook_list,
+					    release_netdev);
+		return;
+	}
+
+	if (table->flags & NFT_TABLE_F_DORMANT)
+		return;
+
 	if (basechain->type->ops_unregister)
 		return basechain->type->ops_unregister(net, ops);
 
-	if (nft_base_chain_netdev(table->family, basechain->ops.hooknum))
-		nft_netdev_unregister_hooks(net, &basechain->hook_list,
-					    release_netdev);
-	else
-		nf_unregister_net_hook(net, &basechain->ops);
+	nf_unregister_net_hook(net, &basechain->ops);
 }
 
 static void nf_tables_unregister_hook(struct net *net,
@@ -11282,11 +11290,9 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 			break;
 		case NFT_MSG_NEWCHAIN:
 			if (nft_trans_chain_update(trans)) {
-				if (!(table->flags & NFT_TABLE_F_DORMANT)) {
-					nft_netdev_unregister_hooks(net,
-								    &nft_trans_chain_hooks(trans),
-								    true);
-				}
+				nft_netdev_unregister_hooks(net, table,
+							    &nft_trans_chain_hooks(trans),
+							    true);
 				free_percpu(nft_trans_chain_stats(trans));
 				kfree(nft_trans_chain_name(trans));
 				nft_trans_destroy(trans);
-- 
2.47.3