[NETFILTER]: ctnetlink: clear helper area and handle unchanged helper

This patch
- Clears private area for helper even if no helper is assigned to
  conntrack. It might be used by old helper.
- Unchanges if the same helper as the used one is specified.
- Does not find helper if no helper is specified. And it does not
  require private area for helper in that case.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 22 insertions, 18 deletions

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index aa1a97ee514b..d6d39e241327 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -830,11 +830,6 @@ ctnetlink_change_helper(struct nf_conn *ct, struct nfattr *cda[])
         char *helpname;
         int err;
 
-        if (!help) {
-                /* FIXME: we need to reallocate and rehash */
-                return -EBUSY;
-        }
-
         /* don't change helper of sibling connections */
         if (ct->master)
                 return -EINVAL;
@@ -843,25 +838,34 @@ ctnetlink_change_helper(struct nf_conn *ct, struct nfattr *cda[])
         if (err < 0)
                 return err;
 
-        helper = __nf_conntrack_helper_find_byname(helpname);
-        if (!helper) {
-                if (!strcmp(helpname, ""))
-                        helper = NULL;
-                else
-                        return -EINVAL;
-        }
-
-        if (help->helper) {
-                if (!helper) {
+        if (!strcmp(helpname, "")) {
+                if (help && help->helper) {
                         /* we had a helper before ... */
                         nf_ct_remove_expectations(ct);
                         help->helper = NULL;
-                } else {
-                        /* need to zero data of old helper */
-                        memset(&help->help, 0, sizeof(help->help));
                 }
+
+                return 0;
         }
 
+        if (!help) {
+                /* FIXME: we need to reallocate and rehash */
+                return -EBUSY;
+        }
+
+        helper = __nf_conntrack_helper_find_byname(helpname);
+        if (helper == NULL)
+                return -EINVAL;
+
+        if (help->helper == helper)
+                return 0;
+
+        if (help->helper)
+                /* we had a helper before ... */
+                nf_ct_remove_expectations(ct);
+
+        /* need to zero data of old helper */
+        memset(&help->help, 0, sizeof(help->help));
         help->helper = helper;
 
         return 0;