netfilter: nft_reject: support for IPv6 and TCP reset

This patch moves nft_reject_ipv4 to nft_reject and adds support
for IPv6 protocol. This patch uses functions included in nf_reject.h
to implement reject by TCP reset.

The code has to be build as a module if NF_TABLES_IPV6 is also a
module to avoid compilation error due to usage of IPv6 functions.
This has been done in Kconfig by using the construct:

 depends on NF_TABLES_IPV6 || !NF_TABLES_IPV6

This seems a bit weird in terms of syntax but works perfectly.

Signed-off-by: Eric Leblond <eric@regit.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv4/netfilter/Kconfig

@@ -40,10 +40,6 @@ config NF_TABLES_IPV4
 	depends on NF_TABLES
 	tristate "IPv4 nf_tables support"
 
-config NFT_REJECT_IPV4
-	depends on NF_TABLES_IPV4
-	tristate "nf_tables IPv4 reject support"
-
 config NFT_CHAIN_ROUTE_IPV4
 	depends on NF_TABLES_IPV4
 	tristate "IPv4 nf_tables route chain support"

net/ipv4/netfilter/Makefile

@@ -28,7 +28,6 @@ obj-$(CONFIG_NF_NAT_SNMP_BASIC) += nf_nat_snmp_basic.o
 obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o
 
 obj-$(CONFIG_NF_TABLES_IPV4) += nf_tables_ipv4.o
-obj-$(CONFIG_NFT_REJECT_IPV4) += nft_reject_ipv4.o
 obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV4) += nft_chain_route_ipv4.o
 obj-$(CONFIG_NFT_CHAIN_NAT_IPV4) += nft_chain_nat_ipv4.o
 obj-$(CONFIG_NF_TABLES_ARP) += nf_tables_arp.o

net/netfilter/Kconfig

@@ -465,6 +465,12 @@ config NFT_QUEUE
 	  This is required if you intend to use the userspace queueing
 	  infrastructure (also known as NFQUEUE) from nftables.
 
+config NFT_REJECT
+	depends on NF_TABLES
+	depends on NF_TABLES_IPV6 || !NF_TABLES_IPV6
+	default m if NETFILTER_ADVANCED=n
+	tristate "Netfilter nf_tables reject support"
+
 config NFT_COMPAT
 	depends on NF_TABLES
 	depends on NETFILTER_XTABLES

net/netfilter/Makefile

@@ -77,6 +77,7 @@ obj-$(CONFIG_NFT_CT)		+= nft_ct.o
 obj-$(CONFIG_NFT_LIMIT)		+= nft_limit.o
 obj-$(CONFIG_NFT_NAT)		+= nft_nat.o
 obj-$(CONFIG_NFT_QUEUE)		+= nft_queue.o
+obj-$(CONFIG_NFT_REJECT) 	+= nft_reject.o
 obj-$(CONFIG_NFT_RBTREE)	+= nft_rbtree.o
 obj-$(CONFIG_NFT_HASH)		+= nft_hash.o
 obj-$(CONFIG_NFT_COUNTER)	+= nft_counter.o

net/ipv4/netfilter/nft_reject_ipv4.c → net/netfilter/nft_reject.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
+ * Copyright (c) 2013 Eric Leblond <eric@regit.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -16,10 +17,16 @@
 #include <linux/netfilter/nf_tables.h>
 #include <net/netfilter/nf_tables.h>
 #include <net/icmp.h>
+#include <net/netfilter/ipv4/nf_reject.h>
+
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+#include <net/netfilter/ipv6/nf_reject.h>
+#endif
 
 struct nft_reject {
 	enum nft_reject_types	type:8;
 	u8			icmp_code;
+	u8			family;
 };
 
 static void nft_reject_eval(const struct nft_expr *expr,
@@ -27,12 +34,25 @@ static void nft_reject_eval(const struct nft_expr *expr,
 			      const struct nft_pktinfo *pkt)
 {
 	struct nft_reject *priv = nft_expr_priv(expr);
+	struct net *net = dev_net((pkt->in != NULL) ? pkt->in : pkt->out);
 
 	switch (priv->type) {
 	case NFT_REJECT_ICMP_UNREACH:
-		icmp_send(pkt->skb, ICMP_DEST_UNREACH, priv->icmp_code, 0);
+		if (priv->family == NFPROTO_IPV4)
+			nf_send_unreach(pkt->skb, priv->icmp_code);
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+		else if (priv->family == NFPROTO_IPV6)
+			nf_send_unreach6(net, pkt->skb, priv->icmp_code,
+				      pkt->hooknum);
+#endif
 		break;
 	case NFT_REJECT_TCP_RST:
+		if (priv->family == NFPROTO_IPV4)
+			nf_send_reset(pkt->skb, pkt->hooknum);
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+		else if (priv->family == NFPROTO_IPV6)
+			nf_send_reset6(net, pkt->skb, pkt->hooknum);
+#endif
 		break;
 	}
 
@@ -53,6 +73,7 @@ static int nft_reject_init(const struct nft_ctx *ctx,
 	if (tb[NFTA_REJECT_TYPE] == NULL)
 		return -EINVAL;
 
+	priv->family = ctx->afi->family;
 	priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
 	switch (priv->type) {
 	case NFT_REJECT_ICMP_UNREACH:
@@ -72,7 +93,7 @@ static int nft_reject_dump(struct sk_buff *skb, const struct nft_expr *expr)
 {
 	const struct nft_reject *priv = nft_expr_priv(expr);
 
-	if (nla_put_be32(skb, NFTA_REJECT_TYPE, priv->type))
+	if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
 		goto nla_put_failure;
 
 	switch (priv->type) {