target/linux/generic/backport-4.14/339-v4.16-netfilter-nft_flow_offload-wait-for-garbage-collecto.patch

   1 From: Pablo Neira Ayuso <pablo@netfilter.org>
   2 Date: Thu, 1 Feb 2018 18:49:00 +0100
   3 Subject: [PATCH] netfilter: nft_flow_offload: wait for garbage collector
   4  to run after cleanup
   5
   6 If netdevice goes down, then flowtable entries are scheduled to be
   7 removed. Wait for garbage collector to have a chance to run so it can
   8 delete them from the hashtable.
   9
  10 The flush call might sleep, so hold the nfnl mutex from
  11 nft_flow_table_iterate() instead of rcu read side lock. The use of the
  12 nfnl mutex is also implicitly fixing races between updates via nfnetlink
  13 and netdevice event.
  14
  15 Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
  16 ---
  17
  18 --- a/net/netfilter/nf_tables_api.c
  19 +++ b/net/netfilter/nf_tables_api.c
  20 @@ -4907,13 +4907,13 @@ void nft_flow_table_iterate(struct net *
  21         struct nft_flowtable *flowtable;
  22         const struct nft_table *table;
  23
  24 -       rcu_read_lock();
  25 -       list_for_each_entry_rcu(table, &net->nft.tables, list) {
  26 -               list_for_each_entry_rcu(flowtable, &table->flowtables, list) {
  27 +       nfnl_lock(NFNL_SUBSYS_NFTABLES);
  28 +       list_for_each_entry(table, &net->nft.tables, list) {
  29 +               list_for_each_entry(flowtable, &table->flowtables, list) {
  30                         iter(&flowtable->data, data);
  31                 }
  32         }
  33 -       rcu_read_unlock();
  34 +       nfnl_unlock(NFNL_SUBSYS_NFTABLES);
  35  }
  36  EXPORT_SYMBOL_GPL(nft_flow_table_iterate);
  37
  38 --- a/net/netfilter/nft_flow_offload.c
  39 +++ b/net/netfilter/nft_flow_offload.c
  40 @@ -208,6 +208,7 @@ static void nft_flow_offload_iterate_cle
  41                                              void *data)
  42  {
  43         nf_flow_table_iterate(flowtable, flow_offload_iterate_cleanup, data);
  44 +       flush_delayed_work(&flowtable->gc_work);
  45  }
  46
  47  static int flow_offload_netdev_event(struct notifier_block *this,