net sched: ipt action fix late binding

This was broken and is fixed with this patch.

//add an ipt action and give it an instance id of 1
sudo tc actions add action ipt -j mark --set-mark 2 index 1
//create a filter which binds to ipt action id 1
sudo tc filter add dev $DEV parent ffff: protocol ip prio 1 u32\
match ip dst 17.0.0.1/32 flowid 1:10 action ipt index 1

Message before bug fix was:
RTNETLINK answers: Invalid argument
We have an error talking to the kernel

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 7 deletions

diff --git a/net/sched/act_ipt.c b/net/sched/act_ipt.c
index 350e134cffb3..8b5270008a6e 100644
--- a/net/sched/act_ipt.c
+++ b/net/sched/act_ipt.c
@@ -96,7 +96,7 @@ static int __tcf_ipt_init(struct tc_action_net *tn, struct nlattr *nla,
         struct tcf_ipt *ipt;
         struct xt_entry_target *td, *t;
         char *tname;
-        int ret = 0, err;
+        int ret = 0, err, exists = 0;
         u32 hook = 0;
         u32 index = 0;
 
@@ -107,18 +107,23 @@ static int __tcf_ipt_init(struct tc_action_net *tn, struct nlattr *nla,
         if (err < 0)
                 return err;
 
-        if (tb[TCA_IPT_HOOK] == NULL)
-                return -EINVAL;
-        if (tb[TCA_IPT_TARG] == NULL)
+        if (tb[TCA_IPT_INDEX] != NULL)
+                index = nla_get_u32(tb[TCA_IPT_INDEX]);
+
+        exists = tcf_hash_check(tn, index, a, bind);
+        if (exists && bind)
+                return 0;
+
+        if (tb[TCA_IPT_HOOK] == NULL || tb[TCA_IPT_TARG] == NULL) {
+                if (exists)
+                        tcf_hash_release(a, bind);
                 return -EINVAL;
+        }
 
         td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);
         if (nla_len(tb[TCA_IPT_TARG]) < td->u.target_size)
                 return -EINVAL;
 
-        if (tb[TCA_IPT_INDEX] != NULL)
-                index = nla_get_u32(tb[TCA_IPT_INDEX]);
-
         if (!tcf_hash_check(tn, index, a, bind)) {
                 ret = tcf_hash_create(tn, index, est, a, sizeof(*ipt), bind,
                                       false);