[PATCH 8/9] netfilter: nf_tables: allow to register flowtable with no devices

[Pablo Neira Ayuso]

A flowtable might be composed of dynamic interfaces only. Such dynamic
interfaces might show up at a later stage. This patch allows users to
register a flowtable with no devices. Once the dynamic interface becomes
available, the user adds the dynamic devices to the flowtable.

Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 1c2c3bb78fa0..897ac5fbe079 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1724,8 +1724,6 @@ static int nf_tables_parse_netdev_hooks(struct net *net,
                        goto err_hook;
                }
        }
-       if (!n)
-               return -EINVAL;
 
        return 0;
 
@@ -1762,6 +1760,9 @@ static int nft_chain_parse_netdev(struct net *net,
                                                   hook_list);
                if (err < 0)
                        return err;
+
+               if (list_empty(hook_list))
+                       return -EINVAL;
        } else {
                return -EINVAL;
        }
@@ -6209,8 +6210,7 @@ static int nft_flowtable_parse_hook(const struct nft_ctx 
*ctx,
                return err;
 
        if (!tb[NFTA_FLOWTABLE_HOOK_NUM] ||
-           !tb[NFTA_FLOWTABLE_HOOK_PRIORITY] ||
-           !tb[NFTA_FLOWTABLE_HOOK_DEVS])
+           !tb[NFTA_FLOWTABLE_HOOK_PRIORITY])
                return -EINVAL;
 
        hooknum = ntohl(nla_get_be32(tb[NFTA_FLOWTABLE_HOOK_NUM]));
@@ -6219,11 +6219,13 @@ static int nft_flowtable_parse_hook(const struct 
nft_ctx *ctx,
 
        priority = ntohl(nla_get_be32(tb[NFTA_FLOWTABLE_HOOK_PRIORITY]));
 
-       err = nf_tables_parse_netdev_hooks(ctx->net,
-                                          tb[NFTA_FLOWTABLE_HOOK_DEVS],
-                                          &flowtable_hook->list);
-       if (err < 0)
-               return err;
+       if (tb[NFTA_FLOWTABLE_HOOK_DEVS]) {
+               err = nf_tables_parse_netdev_hooks(ctx->net,
+                                                  tb[NFTA_FLOWTABLE_HOOK_DEVS],
+                                                  &flowtable_hook->list);
+               if (err < 0)
+                       return err;
+       }
 
        flowtable_hook->priority        = priority;
        flowtable_hook->num             = hooknum;
-- 
2.20.1