netfilter: nft_redir: use `struct nf_nat_range2` throughout and deduplicate eval call-backs

`nf_nat_redirect_ipv4` takes a `struct nf_nat_ipv4_multi_range_compat`,
but converts it internally to a `struct nf_nat_range2`.  Change the
function to take the latter, factor out the code now shared with
`nf_nat_redirect_ipv6`, move the conversion to the xt_REDIRECT module,
and update the ipv4 range initialization in the nft_redir module.

Replace a bare hex constant for 127.0.0.1 with a macro.

Remove `WARN_ON`.  `nf_nat_setup_info` calls `nf_ct_is_confirmed`:

	/* Can't setup nat info for confirmed ct. */
	if (nf_ct_is_confirmed(ct))
		return NF_ACCEPT;

This means that `ct` cannot be null or the kernel will crash, and
implies that `ctinfo` is `IP_CT_NEW` or `IP_CT_RELATED`.

nft_redir has separate ipv4 and ipv6 call-backs which share much of
their code, and an inet one switch containing a switch that calls one of
the others based on the family of the packet.  Merge the ipv4 and ipv6
ones into the inet one in order to get rid of the duplicate code.

Const-qualify the `priv` pointer since we don't need to write through
it.

Assign `priv->flags` to the range instead of OR-ing it in.

Set the `NF_NAT_RANGE_PROTO_SPECIFIED` flag once during init, rather
than on every eval.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 31 insertions, 53 deletions

diff --git a/net/netfilter/nft_redir.c b/net/netfilter/nft_redir.c
index 67cec56bc84a..a70196ffcb1e 100644
--- a/net/netfilter/nft_redir.c
+++ b/net/netfilter/nft_redir.c
@@ -64,6 +64,8 @@ static int nft_redir_init(const struct nft_ctx *ctx,
 		} else {
 			priv->sreg_proto_max = priv->sreg_proto_min;
 		}
+
+		priv->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
 	}
 
 	if (tb[NFTA_REDIR_FLAGS]) {
@@ -99,25 +101,37 @@ nla_put_failure:
 	return -1;
 }
 
-static void nft_redir_ipv4_eval(const struct nft_expr *expr,
-				struct nft_regs *regs,
-				const struct nft_pktinfo *pkt)
+static void nft_redir_eval(const struct nft_expr *expr,
+			   struct nft_regs *regs,
+			   const struct nft_pktinfo *pkt)
 {
-	struct nft_redir *priv = nft_expr_priv(expr);
-	struct nf_nat_ipv4_multi_range_compat mr;
+	const struct nft_redir *priv = nft_expr_priv(expr);
+	struct nf_nat_range2 range;
 
-	memset(&mr, 0, sizeof(mr));
+	memset(&range, 0, sizeof(range));
+	range.flags = priv->flags;
 	if (priv->sreg_proto_min) {
-		mr.range[0].min.all = (__force __be16)nft_reg_load16(
-			&regs->data[priv->sreg_proto_min]);
-		mr.range[0].max.all = (__force __be16)nft_reg_load16(
-			&regs->data[priv->sreg_proto_max]);
-		mr.range[0].flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+		range.min_proto.all = (__force __be16)
+			nft_reg_load16(&regs->data[priv->sreg_proto_min]);
+		range.max_proto.all = (__force __be16)
+			nft_reg_load16(&regs->data[priv->sreg_proto_max]);
 	}
 
-	mr.range[0].flags |= priv->flags;
-
-	regs->verdict.code = nf_nat_redirect_ipv4(pkt->skb, &mr, nft_hook(pkt));
+	switch (nft_pf(pkt)) {
+	case NFPROTO_IPV4:
+		regs->verdict.code = nf_nat_redirect_ipv4(pkt->skb, &range,
+							  nft_hook(pkt));
+		break;
+#ifdef CONFIG_NF_TABLES_IPV6
+	case NFPROTO_IPV6:
+		regs->verdict.code = nf_nat_redirect_ipv6(pkt->skb, &range,
+							  nft_hook(pkt));
+		break;
+#endif
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
 }
 
 static void
@@ -130,7 +144,7 @@ static struct nft_expr_type nft_redir_ipv4_type;
 static const struct nft_expr_ops nft_redir_ipv4_ops = {
 	.type		= &nft_redir_ipv4_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_redir)),
-	.eval		= nft_redir_ipv4_eval,
+	.eval		= nft_redir_eval,
 	.init		= nft_redir_init,
 	.destroy	= nft_redir_ipv4_destroy,
 	.dump		= nft_redir_dump,
@@ -148,28 +162,6 @@ static struct nft_expr_type nft_redir_ipv4_type __read_mostly = {
 };
 
 #ifdef CONFIG_NF_TABLES_IPV6
-static void nft_redir_ipv6_eval(const struct nft_expr *expr,
-				struct nft_regs *regs,
-				const struct nft_pktinfo *pkt)
-{
-	struct nft_redir *priv = nft_expr_priv(expr);
-	struct nf_nat_range2 range;
-
-	memset(&range, 0, sizeof(range));
-	if (priv->sreg_proto_min) {
-		range.min_proto.all = (__force __be16)nft_reg_load16(
-			&regs->data[priv->sreg_proto_min]);
-		range.max_proto.all = (__force __be16)nft_reg_load16(
-			&regs->data[priv->sreg_proto_max]);
-		range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
-	}
-
-	range.flags |= priv->flags;
-
-	regs->verdict.code =
-		nf_nat_redirect_ipv6(pkt->skb, &range, nft_hook(pkt));
-}
-
 static void
 nft_redir_ipv6_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 {
@@ -180,7 +172,7 @@ static struct nft_expr_type nft_redir_ipv6_type;
 static const struct nft_expr_ops nft_redir_ipv6_ops = {
 	.type		= &nft_redir_ipv6_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_redir)),
-	.eval		= nft_redir_ipv6_eval,
+	.eval		= nft_redir_eval,
 	.init		= nft_redir_init,
 	.destroy	= nft_redir_ipv6_destroy,
 	.dump		= nft_redir_dump,
@@ -199,20 +191,6 @@ static struct nft_expr_type nft_redir_ipv6_type __read_mostly = {
 #endif
 
 #ifdef CONFIG_NF_TABLES_INET
-static void nft_redir_inet_eval(const struct nft_expr *expr,
-				struct nft_regs *regs,
-				const struct nft_pktinfo *pkt)
-{
-	switch (nft_pf(pkt)) {
-	case NFPROTO_IPV4:
-		return nft_redir_ipv4_eval(expr, regs, pkt);
-	case NFPROTO_IPV6:
-		return nft_redir_ipv6_eval(expr, regs, pkt);
-	}
-
-	WARN_ON_ONCE(1);
-}
-
 static void
 nft_redir_inet_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 {
@@ -223,7 +201,7 @@ static struct nft_expr_type nft_redir_inet_type;
 static const struct nft_expr_ops nft_redir_inet_ops = {
 	.type		= &nft_redir_inet_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_redir)),
-	.eval		= nft_redir_inet_eval,
+	.eval		= nft_redir_eval,
 	.init		= nft_redir_init,
 	.destroy	= nft_redir_inet_destroy,
 	.dump		= nft_redir_dump,