netfilter: nf_tables: merge route type into core

very little code, so it really doesn't make sense to have extra
modules or even a kconfig knob for this.

Merge them and make functionality available unconditionally.
The merge makes inet family route support trivial, so add it
as well here.

Before:
   text	   data	    bss	    dec	    hex	filename
    835	    832	      0	   1667	    683 nft_chain_route_ipv4.ko
    870	    832	      0	   1702	    6a6	nft_chain_route_ipv6.ko
 111568	   2556	    529	 114653	  1bfdd	nf_tables.ko

After:
   text	   data	    bss	    dec	    hex	filename
 113133	   2556	    529	 116218	  1c5fa	nf_tables.ko

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 169 insertions, 0 deletions

diff --git a/net/netfilter/nft_chain_route.c b/net/netfilter/nft_chain_route.c
new file mode 100644
index 000000000000..8826bbe71136
--- /dev/null
+++ b/net/netfilter/nft_chain_route.c
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/skbuff.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables_ipv4.h>
+#include <net/netfilter/nf_tables_ipv6.h>
+#include <net/route.h>
+#include <net/ip.h>
+
+#ifdef CONFIG_NF_TABLES_IPV4
+static unsigned int nf_route_table_hook4(void *priv,
+					 struct sk_buff *skb,
+					 const struct nf_hook_state *state)
+{
+	const struct iphdr *iph;
+	struct nft_pktinfo pkt;
+	__be32 saddr, daddr;
+	unsigned int ret;
+	u32 mark;
+	int err;
+	u8 tos;
+
+	nft_set_pktinfo(&pkt, skb, state);
+	nft_set_pktinfo_ipv4(&pkt, skb);
+
+	mark = skb->mark;
+	iph = ip_hdr(skb);
+	saddr = iph->saddr;
+	daddr = iph->daddr;
+	tos = iph->tos;
+
+	ret = nft_do_chain(&pkt, priv);
+	if (ret == NF_ACCEPT) {
+		iph = ip_hdr(skb);
+
+		if (iph->saddr != saddr ||
+		    iph->daddr != daddr ||
+		    skb->mark != mark ||
+		    iph->tos != tos) {
+			err = ip_route_me_harder(state->net, skb, RTN_UNSPEC);
+			if (err < 0)
+				ret = NF_DROP_ERR(err);
+		}
+	}
+	return ret;
+}
+
+static const struct nft_chain_type nft_chain_route_ipv4 = {
+	.name		= "route",
+	.type		= NFT_CHAIN_T_ROUTE,
+	.family		= NFPROTO_IPV4,
+	.hook_mask	= (1 << NF_INET_LOCAL_OUT),
+	.hooks		= {
+		[NF_INET_LOCAL_OUT]	= nf_route_table_hook4,
+	},
+};
+#endif
+
+#ifdef CONFIG_NF_TABLES_IPV6
+static unsigned int nf_route_table_hook6(void *priv,
+					 struct sk_buff *skb,
+					 const struct nf_hook_state *state)
+{
+	struct in6_addr saddr, daddr;
+	struct nft_pktinfo pkt;
+	u32 mark, flowlabel;
+	unsigned int ret;
+	u8 hop_limit;
+	int err;
+
+	nft_set_pktinfo(&pkt, skb, state);
+	nft_set_pktinfo_ipv6(&pkt, skb);
+
+	/* save source/dest address, mark, hoplimit, flowlabel, priority */
+	memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
+	memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
+	mark = skb->mark;
+	hop_limit = ipv6_hdr(skb)->hop_limit;
+
+	/* flowlabel and prio (includes version, which shouldn't change either)*/
+	flowlabel = *((u32 *)ipv6_hdr(skb));
+
+	ret = nft_do_chain(&pkt, priv);
+	if (ret == NF_ACCEPT &&
+	    (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr)) ||
+	     memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr)) ||
+	     skb->mark != mark ||
+	     ipv6_hdr(skb)->hop_limit != hop_limit ||
+	     flowlabel != *((u32 *)ipv6_hdr(skb)))) {
+		err = nf_ip6_route_me_harder(state->net, skb);
+		if (err < 0)
+			ret = NF_DROP_ERR(err);
+	}
+
+	return ret;
+}
+
+static const struct nft_chain_type nft_chain_route_ipv6 = {
+	.name		= "route",
+	.type		= NFT_CHAIN_T_ROUTE,
+	.family		= NFPROTO_IPV6,
+	.hook_mask	= (1 << NF_INET_LOCAL_OUT),
+	.hooks		= {
+		[NF_INET_LOCAL_OUT]	= nf_route_table_hook6,
+	},
+};
+#endif
+
+#ifdef CONFIG_NF_TABLES_INET
+static unsigned int nf_route_table_inet(void *priv,
+					struct sk_buff *skb,
+					const struct nf_hook_state *state)
+{
+	struct nft_pktinfo pkt;
+
+	switch (state->pf) {
+	case NFPROTO_IPV4:
+		return nf_route_table_hook4(priv, skb, state);
+	case NFPROTO_IPV6:
+		return nf_route_table_hook6(priv, skb, state);
+	default:
+		nft_set_pktinfo(&pkt, skb, state);
+		break;
+	}
+
+	return nft_do_chain(&pkt, priv);
+}
+
+static const struct nft_chain_type nft_chain_route_inet = {
+	.name		= "route",
+	.type		= NFT_CHAIN_T_ROUTE,
+	.family		= NFPROTO_INET,
+	.hook_mask	= (1 << NF_INET_LOCAL_OUT),
+	.hooks		= {
+		[NF_INET_LOCAL_OUT]	= nf_route_table_inet,
+	},
+};
+#endif
+
+void __init nft_chain_route_init(void)
+{
+#ifdef CONFIG_NF_TABLES_IPV6
+	nft_register_chain_type(&nft_chain_route_ipv6);
+#endif
+#ifdef CONFIG_NF_TABLES_IPV4
+	nft_register_chain_type(&nft_chain_route_ipv4);
+#endif
+#ifdef CONFIG_NF_TABLES_INET
+	nft_register_chain_type(&nft_chain_route_inet);
+#endif
+}
+
+void __exit nft_chain_route_fini(void)
+{
+#ifdef CONFIG_NF_TABLES_IPV6
+	nft_unregister_chain_type(&nft_chain_route_ipv6);
+#endif
+#ifdef CONFIG_NF_TABLES_IPV4
+	nft_unregister_chain_type(&nft_chain_route_ipv4);
+#endif
+#ifdef CONFIG_NF_TABLES_INET
+	nft_unregister_chain_type(&nft_chain_route_inet);
+#endif
+}