netfilter: nf_tables: make nft_set_do_lookup available unconditionally

This function was added for retpoline mitigation and is replaced by a
static inline helper if mitigations are not enabled.

Enable this helper function unconditionally so next patch can add a lookup
restart mechanism to fix possible false negatives while transactions are
in progress.

Adding lookup restarts in nft_lookup_eval doesn't work as nft_objref would
then need the same copypaste loop.

This patch is separate to ease review of the actual bug fix.

Suggested-by: Pablo Neira Ayuso <[email protected]>
Signed-off-by: Florian Westphal <[email protected]>

Author: Florian Westphal

include/net/netfilter/nf_tables_core.h

@@ -109,17 +109,11 @@ nft_hash_lookup_fast(const struct net *net, const struct nft_set *set,
 const struct nft_set_ext *
 nft_hash_lookup(const struct net *net, const struct nft_set *set,
 		const u32 *key);
+#endif
+
 const struct nft_set_ext *
 nft_set_do_lookup(const struct net *net, const struct nft_set *set,
 		  const u32 *key);
-#else
-static inline const struct nft_set_ext *
-nft_set_do_lookup(const struct net *net, const struct nft_set *set,
-		  const u32 *key)
-{
-	return set->ops->lookup(net, set, key);
-}
-#endif
 
 /* called from nft_pipapo_avx2.c */
 const struct nft_set_ext *

net/netfilter/nft_lookup.c

@@ -24,11 +24,11 @@ struct nft_lookup {
 	struct nft_set_binding		binding;
 };
 
-#ifdef CONFIG_MITIGATION_RETPOLINE
-const struct nft_set_ext *
-nft_set_do_lookup(const struct net *net, const struct nft_set *set,
-		  const u32 *key)
+static const struct nft_set_ext *
+__nft_set_do_lookup(const struct net *net, const struct nft_set *set,
+		    const u32 *key)
 {
+#ifdef CONFIG_MITIGATION_RETPOLINE
 	if (set->ops == &nft_set_hash_fast_type.ops)
 		return nft_hash_lookup_fast(net, set, key);
 	if (set->ops == &nft_set_hash_type.ops)
@@ -51,10 +51,17 @@ nft_set_do_lookup(const struct net *net, const struct nft_set *set,
 		return nft_rbtree_lookup(net, set, key);
 
 	WARN_ON_ONCE(1);
+#endif
 	return set->ops->lookup(net, set, key);
 }
+
+const struct nft_set_ext *
+nft_set_do_lookup(const struct net *net, const struct nft_set *set,
+		  const u32 *key)
+{
+	return __nft_set_do_lookup(net, set, key);
+}
 EXPORT_SYMBOL_GPL(nft_set_do_lookup);
-#endif
 
 void nft_lookup_eval(const struct nft_expr *expr,
 		     struct nft_regs *regs,