netfilter: REJECT: separate reusable code

This patch prepares the addition of TCP reset support in
the nft_reject module by moving reusable code into a header
file.

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

1 files changed, 10 insertions, 130 deletions

diff --git a/net/ipv4/netfilter/ipt_REJECT.c b/net/ipv4/netfilter/ipt_REJECT.c
index b969131ad1c1..5b6e0df4ccff 100644
--- a/net/ipv4/netfilter/ipt_REJECT.c
+++ b/net/ipv4/netfilter/ipt_REJECT.c
@@ -17,10 +17,6 @@
 #include <linux/udp.h>
 #include <linux/icmp.h>
 #include <net/icmp.h>
-#include <net/ip.h>
-#include <net/tcp.h>
-#include <net/route.h>
-#include <net/dst.h>
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter_ipv4/ip_tables.h>
 #include <linux/netfilter_ipv4/ipt_REJECT.h>
@@ -28,128 +24,12 @@
 #include <linux/netfilter_bridge.h>
 #endif
 
+#include <net/netfilter/ipv4/nf_reject.h>
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
 MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv4");
 
-/* Send RST reply */
-static void send_reset(struct sk_buff *oldskb, int hook)
-{
-	struct sk_buff *nskb;
-	const struct iphdr *oiph;
-	struct iphdr *niph;
-	const struct tcphdr *oth;
-	struct tcphdr _otcph, *tcph;
-
-	/* IP header checks: fragment. */
-	if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
-		return;
-
-	oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb),
-				 sizeof(_otcph), &_otcph);
-	if (oth == NULL)
-		return;
-
-	/* No RST for RST. */
-	if (oth->rst)
-		return;
-
-	if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
-		return;
-
-	/* Check checksum */
-	if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP))
-		return;
-	oiph = ip_hdr(oldskb);
-
-	nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +
-			 LL_MAX_HEADER, GFP_ATOMIC);
-	if (!nskb)
-		return;
-
-	skb_reserve(nskb, LL_MAX_HEADER);
-
-	skb_reset_network_header(nskb);
-	niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr));
-	niph->version	= 4;
-	niph->ihl	= sizeof(struct iphdr) / 4;
-	niph->tos	= 0;
-	niph->id	= 0;
-	niph->frag_off	= htons(IP_DF);
-	niph->protocol	= IPPROTO_TCP;
-	niph->check	= 0;
-	niph->saddr	= oiph->daddr;
-	niph->daddr	= oiph->saddr;
-
-	skb_reset_transport_header(nskb);
-	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
-	memset(tcph, 0, sizeof(*tcph));
-	tcph->source	= oth->dest;
-	tcph->dest	= oth->source;
-	tcph->doff	= sizeof(struct tcphdr) / 4;
-
-	if (oth->ack)
-		tcph->seq = oth->ack_seq;
-	else {
-		tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin +
-				      oldskb->len - ip_hdrlen(oldskb) -
-				      (oth->doff << 2));
-		tcph->ack = 1;
-	}
-
-	tcph->rst	= 1;
-	tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr,
-				    niph->daddr, 0);
-	nskb->ip_summed = CHECKSUM_PARTIAL;
-	nskb->csum_start = (unsigned char *)tcph - nskb->head;
-	nskb->csum_offset = offsetof(struct tcphdr, check);
-
-	/* ip_route_me_harder expects skb->dst to be set */
-	skb_dst_set_noref(nskb, skb_dst(oldskb));
-
-	nskb->protocol = htons(ETH_P_IP);
-	if (ip_route_me_harder(nskb, RTN_UNSPEC))
-		goto free_nskb;
-
-	niph->ttl	= ip4_dst_hoplimit(skb_dst(nskb));
-
-	/* "Never happens" */
-	if (nskb->len > dst_mtu(skb_dst(nskb)))
-		goto free_nskb;
-
-	nf_ct_attach(nskb, oldskb);
-
-#ifdef CONFIG_BRIDGE_NETFILTER
-	/* If we use ip_local_out for bridged traffic, the MAC source on
-	 * the RST will be ours, instead of the destination's.  This confuses
-	 * some routers/firewalls, and they drop the packet.  So we need to
-	 * build the eth header using the original destination's MAC as the
-	 * source, and send the RST packet directly.
-	 */
-	if (oldskb->nf_bridge) {
-		struct ethhdr *oeth = eth_hdr(oldskb);
-		nskb->dev = oldskb->nf_bridge->physindev;
-		niph->tot_len = htons(nskb->len);
-		ip_send_check(niph);
-		if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),
-				    oeth->h_source, oeth->h_dest, nskb->len) < 0)
-			goto free_nskb;
-		dev_queue_xmit(nskb);
-	} else
-#endif
-		ip_local_out(nskb);
-
-	return;
-
- free_nskb:
-	kfree_skb(nskb);
-}
-
-static inline void send_unreach(struct sk_buff *skb_in, int code)
-{
-	icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);
-}
-
 static unsigned int
 reject_tg(struct sk_buff *skb, const struct xt_action_param *par)
 {
@@ -157,28 +37,28 @@ reject_tg(struct sk_buff *skb, const struct xt_action_param *par)
 
 	switch (reject->with) {
 	case IPT_ICMP_NET_UNREACHABLE:
-		send_unreach(skb, ICMP_NET_UNREACH);
+		nf_send_unreach(skb, ICMP_NET_UNREACH);
 		break;
 	case IPT_ICMP_HOST_UNREACHABLE:
-		send_unreach(skb, ICMP_HOST_UNREACH);
+		nf_send_unreach(skb, ICMP_HOST_UNREACH);
 		break;
 	case IPT_ICMP_PROT_UNREACHABLE:
-		send_unreach(skb, ICMP_PROT_UNREACH);
+		nf_send_unreach(skb, ICMP_PROT_UNREACH);
 		break;
 	case IPT_ICMP_PORT_UNREACHABLE:
-		send_unreach(skb, ICMP_PORT_UNREACH);
+		nf_send_unreach(skb, ICMP_PORT_UNREACH);
 		break;
 	case IPT_ICMP_NET_PROHIBITED:
-		send_unreach(skb, ICMP_NET_ANO);
+		nf_send_unreach(skb, ICMP_NET_ANO);
 		break;
 	case IPT_ICMP_HOST_PROHIBITED:
-		send_unreach(skb, ICMP_HOST_ANO);
+		nf_send_unreach(skb, ICMP_HOST_ANO);
 		break;
 	case IPT_ICMP_ADMIN_PROHIBITED:
-		send_unreach(skb, ICMP_PKT_FILTERED);
+		nf_send_unreach(skb, ICMP_PKT_FILTERED);
 		break;
 	case IPT_TCP_RESET:
-		send_reset(skb, par->hooknum);
+		nf_send_reset(skb, par->hooknum);
 	case IPT_ICMP_ECHOREPLY:
 		/* Doesn't happen. */
 		break;