udp: provide udp{4,6}_lib_lookup for nf_socket_ipv{4,6}

Since commit ca065d0cf80f ("udp: no longer use SLAB_DESTROY_BY_RCU")
the udp6_lib_lookup and udp4_lib_lookup functions are only
provided when it is actually possible to call them.

However, moving the callers now caused a link error:

net/built-in.o: In function `nf_sk_lookup_slow_v6':
(.text+0x131a39): undefined reference to `udp6_lib_lookup'
net/ipv4/netfilter/nf_socket_ipv4.o: In function `nf_sk_lookup_slow_v4':
nf_socket_ipv4.c:(.text.nf_sk_lookup_slow_v4+0x114): undefined reference to `udp4_lib_lookup'

This extends the #ifdef so we also provide the functions when
CONFIG_NF_SOCKET_IPV4 or CONFIG_NF_SOCKET_IPV6, respectively
are set.

Fixes: 8db4c5be88f6 ("netfilter: move socket lookup infrastructure to nf_socket_ipv{4,6}.c")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv4/udp.c

@@ -580,7 +580,8 @@ EXPORT_SYMBOL_GPL(udp4_lib_lookup_skb);
  * Does increment socket refcount.
  */
 #if IS_ENABLED(CONFIG_NETFILTER_XT_MATCH_SOCKET) || \
-    IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TPROXY)
+    IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TPROXY) || \
+    IS_ENABLED(CONFIG_NF_SOCKET_IPV4)
 struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 			     __be32 daddr, __be16 dport, int dif)
 {

net/ipv6/udp.c

@@ -302,7 +302,8 @@ EXPORT_SYMBOL_GPL(udp6_lib_lookup_skb);
  * Does increment socket refcount.
  */
 #if IS_ENABLED(CONFIG_NETFILTER_XT_MATCH_SOCKET) || \
-    IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TPROXY)
+    IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TPROXY) || \
+    IS_ENABLED(CONFIG_NF_SOCKET_IPV6)
 struct sock *udp6_lib_lookup(struct net *net, const struct in6_addr *saddr, __be16 sport,
 			     const struct in6_addr *daddr, __be16 dport, int dif)
 {