sched, cls: check if we could overwrite actions when changing a filter

When actions are attached to a filter, they are a part of the filter
itself, so when changing a filter we should allow to overwrite the actions
inside as well.

In my specific case, when I tried to _append_ a new action to an existing
filter which already has an action, I got EEXIST since kernel refused
to overwrite the existing one in kernel.

This patch checks if we are changing the filter checking NLM_F_CREATE flag
(Sigh, filters don't use NLM_F_REPLACE...) and then passes the boolean down
to actions. This fixes the problem above.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index 8e2158ab551c..cacf01bd04f0 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -83,7 +83,7 @@ static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
                              struct tcf_proto *tp, unsigned long base,
                              u32 handle, struct nlattr **tca,
-                             unsigned long *arg)
+                             unsigned long *arg, bool ovr)
 {
         struct nlattr *tb[TCA_CGROUP_MAX + 1];
         struct cls_cgroup_head *head = tp->root;
@@ -119,7 +119,7 @@ static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
                 return err;
 
         tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
-        err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e);
+        err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr);
         if (err < 0)
                 return err;