[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>

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index aa1a97e..d6d39e2 100644 (file)
--- 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;