netfilter: nf_ct_helper: bail out on duplicated helpers

Don't allow registration of helpers using the same tuple:

	{ l3proto, l4proto, src-port }

We lookup for the helper from the packet path using this tuple through
__nf_ct_helper_find(). Therefore, we have to avoid having two helpers
with the same tuple to ensure predictible behaviour.

Don't compare the helper string names anymore since it is valid to
register two helpers with the same name, but using different tuples.
This is also implicitly fixing up duplicated helper registration via
ports= modparam since the name comparison was defeating the tuple
duplication validation.

Reported-by: Feng Gao <[email protected]>
Reported-by: Taehee Yoo <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>

diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 3b40ec575cd56a7b73c0b25d9c8decdda979d842..48de9be45a9a4537349257d34c58c3815044bb43 100644 (file)
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -361,9 +361,10 @@ EXPORT_SYMBOL_GPL(nf_ct_helper_log);
 
 int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
 {
-       int ret = 0;
-       struct nf_conntrack_helper *cur;
+       struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
        unsigned int h = helper_hash(&me->tuple);
+       struct nf_conntrack_helper *cur;
+       int ret = 0;
 
        BUG_ON(me->expect_policy == NULL);
        BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
@@ -371,9 +372,7 @@ int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
 
        mutex_lock(&nf_ct_helper_mutex);
        hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
-               if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
-                   cur->tuple.src.l3num == me->tuple.src.l3num &&
-                   cur->tuple.dst.protonum == me->tuple.dst.protonum) {
+               if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple, &mask)) {
                        ret = -EEXIST;
                        goto out;
                }