[PATCH nf 1/2] netfilter: nft_flow_offload: wait for garbage collector to run after cleanup

[PATCH nf 1/2] netfilter: nft_flow_offload: wait for garbage collector to run after cleanup

[Pablo Neira Ayuso]

If netdevice goes down, then flowtable entries are scheduled to be
removed. Wait for garbage collector to have a chance to run so it can
delete them from the hashtable.

The flush call might sleep, so hold the nfnl mutex from
nft_flow_table_iterate() instead of rcu read side lock. The use of the
nfnl mutex is also implicitly fixing races between updates via nfnetlink
and netdevice event.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c    | 8 ++++----
 net/netfilter/nft_flow_offload.c | 1 +
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 0791813a1e7d..07dd1fac78a8 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5006,13 +5006,13 @@ void nft_flow_table_iterate(struct net *net,
 	struct nft_flowtable *flowtable;
 	const struct nft_table *table;
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(table, &net->nft.tables, list) {
-		list_for_each_entry_rcu(flowtable, &table->flowtables, list) {
+	nfnl_lock(NFNL_SUBSYS_NFTABLES);
+	list_for_each_entry(table, &net->nft.tables, list) {
+		list_for_each_entry(flowtable, &table->flowtables, list) {
 			iter(&flowtable->data, data);
 		}
 	}
-	rcu_read_unlock();
+	nfnl_unlock(NFNL_SUBSYS_NFTABLES);
 }
 EXPORT_SYMBOL_GPL(nft_flow_table_iterate);
 
diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
index 4503b8dcf9c0..1739ff8ca21f 100644
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -208,6 +208,7 @@ static void nft_flow_offload_iterate_cleanup(struct nf_flowtable *flowtable,
 					     void *data)
 {
 	nf_flow_table_iterate(flowtable, flow_offload_iterate_cleanup, data);
+	flush_delayed_work(&flowtable->gc_work);
 }
 
 static int flow_offload_netdev_event(struct notifier_block *this,
-- 
2.11.0

[PATCH nf 2/2] netfilter: nft_flow_offload: no need to flush entries on module removal

[Pablo Neira Ayuso]

nft_flow_offload module removal does not require to flush existing
flowtables, it is valid to remove this module while keeping flowtables
around.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nft_flow_offload.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
index 1739ff8ca21f..e5c45c7ac02a 100644
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -247,14 +247,8 @@ static int __init nft_flow_offload_module_init(void)
 
 static void __exit nft_flow_offload_module_exit(void)
 {
-	struct net *net;
-
 	nft_unregister_expr(&nft_flow_offload_type);
 	unregister_netdevice_notifier(&flow_offload_netdev_notifier);
-	rtnl_lock();
-	for_each_net(net)
-		nft_flow_table_iterate(net, nft_flow_offload_iterate_cleanup, NULL);
-	rtnl_unlock();
 }
 
 module_init(nft_flow_offload_module_init);
-- 
2.11.0