netfilter: nft_fib: allow from forward/input without iif selector

This removes the restriction of needing iif selector in the
forward/input hooks for fib lookups when requested result is
oif/oifname.

Removing this restriction allows "loose" lookups from the forward hooks.

Fixes: be8be04 ("netfilter: nft_fib: reverse path filter for policy-based routing on iif")
Signed-off-by: Eric Garver <eric@garver.life>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_fib.c

@@ -35,11 +35,9 @@ int nft_fib_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
 	switch (priv->result) {
 	case NFT_FIB_RESULT_OIF:
 	case NFT_FIB_RESULT_OIFNAME:
-		hooks = (1 << NF_INET_PRE_ROUTING);
-		if (priv->flags & NFTA_FIB_F_IIF) {
-			hooks |= (1 << NF_INET_LOCAL_IN) |
-				 (1 << NF_INET_FORWARD);
-		}
+		hooks = (1 << NF_INET_PRE_ROUTING) |
+			(1 << NF_INET_LOCAL_IN) |
+			(1 << NF_INET_FORWARD);
 		break;
 	case NFT_FIB_RESULT_ADDRTYPE:
 		if (priv->flags & NFTA_FIB_F_IIF)