160-netfilter_route.patch

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Index: linux-2.6.21.7/include/linux/netfilter_ipv4/ipt_ROUTE.h
===================================================================
--- /dev/null
+++ linux-2.6.21.7/include/linux/netfilter_ipv4/ipt_ROUTE.h
@@ -0,0 +1,23 @@
+/* Header file for iptables ipt_ROUTE target
+ *
+ * (C) 2002 by C閐ric de Launois <[e-mail]>
+ *
+ * This software is distributed under GNU GPL v2, 1991
+ */
+#ifndef _IPT_ROUTE_H_target
+#define _IPT_ROUTE_H_target
+
+#define IPT_ROUTE_IFNAMSIZ 16
+
+struct ipt_route_target_info {
+	char      oif[IPT_ROUTE_IFNAMSIZ];      /* Output Interface Name */
+	char      iif[IPT_ROUTE_IFNAMSIZ];      /* Input Interface Name  */
+	u_int32_t gw;                           /* IP address of gateway */
+	u_int8_t  flags;
+};
+
+/* Values for "flags" field */
+#define IPT_ROUTE_CONTINUE        0x01
+#define IPT_ROUTE_TEE             0x02
+
+#endif /*_IPT_ROUTE_H_target*/
Index: linux-2.6.21.7/include/linux/netfilter_ipv6/ip6t_ROUTE.h
===================================================================
--- /dev/null
+++ linux-2.6.21.7/include/linux/netfilter_ipv6/ip6t_ROUTE.h
@@ -0,0 +1,23 @@
+/* Header file for iptables ip6t_ROUTE target
+ *
+ * (C) 2003 by C閐ric de Launois <[e-mail]>
+ *
+ * This software is distributed under GNU GPL v2, 1991
+ */
+#ifndef _IPT_ROUTE_H_target
+#define _IPT_ROUTE_H_target
+
+#define IP6T_ROUTE_IFNAMSIZ 16
+
+struct ip6t_route_target_info {
+	char      oif[IP6T_ROUTE_IFNAMSIZ];     /* Output Interface Name */
+	char      iif[IP6T_ROUTE_IFNAMSIZ];     /* Input Interface Name  */
+	u_int32_t gw[4];                        /* IPv6 address of gateway */
+	u_int8_t  flags;
+};
+
+/* Values for "flags" field */
+#define IP6T_ROUTE_CONTINUE        0x01
+#define IP6T_ROUTE_TEE             0x02
+
+#endif /*_IP6T_ROUTE_H_target*/
Index: linux-2.6.21.7/net/ipv4/netfilter/ipt_ROUTE.c
===================================================================
--- /dev/null
+++ linux-2.6.21.7/net/ipv4/netfilter/ipt_ROUTE.c
@@ -0,0 +1,483 @@
+/*
+ * This implements the ROUTE target, which enables you to setup unusual
+ * routes not supported by the standard kernel routing table.
+ *
+ * Copyright (C) 2002 Cedric de Launois <[e-mail]>
+ *
+ * v 1.11 2004/11/23
+ *
+ * This software is distributed under GNU GPL v2, 1991
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ip_conntrack.h>
+#include <linux/netfilter_ipv4/ipt_ROUTE.h>
+#include <linux/netdevice.h>
+#include <linux/route.h>
+#include <linux/version.h>
+#include <linux/if_arp.h>
+#include <net/ip.h>
+#include <net/route.h>
+#include <net/icmp.h>
+#include <net/checksum.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Cedric de Launois <[e-mail]>");
+MODULE_DESCRIPTION("iptables ROUTE target module");
+
+/* Try to route the packet according to the routing keys specified in
+ * route_info. Keys are :
+ *  - ifindex : 
+ *      0 if no oif preferred, 
+ *      otherwise set to the index of the desired oif
+ *  - route_info->gw :
+ *      0 if no gateway specified,
+ *      otherwise set to the next host to which the pkt must be routed
+ * If success, skb->dev is the output device to which the packet must 
+ * be sent and skb->dst is not NULL
+ *
+ * RETURN: -1 if an error occured
+ *          1 if the packet was succesfully routed to the 
+ *            destination desired
+ *          0 if the kernel routing table could not route the packet
+ *            according to the keys specified
+ */
+static int route(struct sk_buff *skb,
+		 unsigned int ifindex,
+		 const struct ipt_route_target_info *route_info)
+{
+	int err;
+	struct rtable *rt;
+	struct iphdr *iph = skb->nh.iph;
+	struct flowi fl = {
+		.oif = ifindex,
+		.nl_u = {
+			.ip4_u = {
+				.daddr = iph->daddr,
+				.saddr = 0,
+				.tos = RT_TOS(iph->tos),
+				.scope = RT_SCOPE_UNIVERSE,
+			}
+		} 
+	};
+	
+	/* The destination address may be overloaded by the target */
+	if (route_info->gw)
+		fl.fl4_dst = route_info->gw;
+	
+	/* Trying to route the packet using the standard routing table. */
+	if ((err = ip_route_output_key(&rt, &fl))) {
+		if (net_ratelimit()) 
+			DEBUGP("ipt_ROUTE: couldn't route pkt (err: %i)",err);
+		return -1;
+	}
+	
+	/* Drop old route. */
+	dst_release(skb->dst);
+	skb->dst = NULL;
+
+	/* Success if no oif specified or if the oif correspond to the 
+	 * one desired */
+	if (!ifindex || rt->u.dst.dev->ifindex == ifindex) {
+		skb->dst = &rt->u.dst;
+		skb->dev = skb->dst->dev;
+		skb->protocol = htons(ETH_P_IP);
+		return 1;
+	}
+	
+	/* The interface selected by the routing table is not the one
+	 * specified by the user. This may happen because the dst address
+	 * is one of our own addresses.
+	 */
+	if (net_ratelimit()) 
+		DEBUGP("ipt_ROUTE: failed to route as desired gw=%u.%u.%u.%u oif=%i (got oif=%i)\n", 
+		       NIPQUAD(route_info->gw), ifindex, rt->u.dst.dev->ifindex);
+	
+	return 0;
+}
+
+
+/* Stolen from ip_finish_output2
+ * PRE : skb->dev is set to the device we are leaving by
+ *       skb->dst is not NULL
+ * POST: the packet is sent with the link layer header pushed
+ *       the packet is destroyed
+ */
+static void ip_direct_send(struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb->dst;
+	struct hh_cache *hh = dst->hh;
+	struct net_device *dev = dst->dev;
+	int hh_len = LL_RESERVED_SPACE(dev);
+
+	/* Be paranoid, rather than too clever. */
+	if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) {
+		struct sk_buff *skb2;
+
+		skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
+		if (skb2 == NULL) {
+			kfree_skb(skb);
+			return;
+		}
+		if (skb->sk)
+			skb_set_owner_w(skb2, skb->sk);
+		kfree_skb(skb);
+		skb = skb2;
+	}
+
+	if (hh) {
+		int hh_alen;
+
+		read_lock_bh(&hh->hh_lock);
+		hh_alen = HH_DATA_ALIGN(hh->hh_len);
+  		memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
+		read_unlock_bh(&hh->hh_lock);
+		skb_push(skb, hh->hh_len);
+		hh->hh_output(skb);
+	} else if (dst->neighbour)
+		dst->neighbour->output(skb);
+	else {
+		if (net_ratelimit())
+			DEBUGP(KERN_DEBUG "ipt_ROUTE: no hdr & no neighbour cache!\n");
+		kfree_skb(skb);
+	}
+}
+
+
+/* PRE : skb->dev is set to the device we are leaving by
+ * POST: - the packet is directly sent to the skb->dev device, without 
+ *         pushing the link layer header.
+ *       - the packet is destroyed
+ */
+static inline int dev_direct_send(struct sk_buff *skb)
+{
+	return dev_queue_xmit(skb);
+}
+
+
+static unsigned int route_oif(const struct ipt_route_target_info *route_info,
+			      struct sk_buff *skb) 
+{
+	unsigned int ifindex = 0;
+	struct net_device *dev_out = NULL;
+
+	/* The user set the interface name to use.
+	 * Getting the current interface index.
+	 */
+	if ((dev_out = dev_get_by_name(route_info->oif))) {
+		ifindex = dev_out->ifindex;
+	} else {
+		/* Unknown interface name : packet dropped */
+		if (net_ratelimit()) 
+			DEBUGP("ipt_ROUTE: oif interface %s not found\n", route_info->oif);
+		return NF_DROP;
+	}
+
+	/* Trying the standard way of routing packets */
+	switch (route(skb, ifindex, route_info)) {
+	case 1:
+		dev_put(dev_out);
+		if (route_info->flags & IPT_ROUTE_CONTINUE)
+			return IPT_CONTINUE;
+
+		ip_direct_send(skb);
+		return NF_STOLEN;
+
+	case 0:
+		/* Failed to send to oif. Trying the hard way */
+		if (route_info->flags & IPT_ROUTE_CONTINUE)
+			return NF_DROP;
+
+		if (net_ratelimit()) 
+			DEBUGP("ipt_ROUTE: forcing the use of %i\n",
+			       ifindex);
+
+		/* We have to force the use of an interface.
+		 * This interface must be a tunnel interface since
+		 * otherwise we can't guess the hw address for
+		 * the packet. For a tunnel interface, no hw address
+		 * is needed.
+		 */
+		if ((dev_out->type != ARPHRD_TUNNEL)
+		    && (dev_out->type != ARPHRD_IPGRE)) {
+			if (net_ratelimit()) 
+				DEBUGP("ipt_ROUTE: can't guess the hw addr !\n");
+			dev_put(dev_out);
+			return NF_DROP;
+		}
+	
+		/* Send the packet. This will also free skb
+		 * Do not go through the POST_ROUTING hook because 
+		 * skb->dst is not set and because it will probably
+		 * get confused by the destination IP address.
+		 */
+		skb->dev = dev_out;
+		dev_direct_send(skb);
+		dev_put(dev_out);
+		return NF_STOLEN;
+		
+	default:
+		/* Unexpected error */
+		dev_put(dev_out);
+		return NF_DROP;
+	}
+}
+
+
+static unsigned int route_iif(const struct ipt_route_target_info *route_info,
+			      struct sk_buff *skb) 
+{
+	struct net_device *dev_in = NULL;
+
+	/* Getting the current interface index. */
+	if (!(dev_in = dev_get_by_name(route_info->iif))) {
+		if (net_ratelimit()) 
+			DEBUGP("ipt_ROUTE: iif interface %s not found\n", route_info->iif);
+		return NF_DROP;
+	}
+
+	skb->dev = dev_in;
+	dst_release(skb->dst);
+	skb->dst = NULL;
+
+	netif_rx(skb);
+	dev_put(dev_in);
+	return NF_STOLEN;
+}
+
+
+static unsigned int route_gw(const struct ipt_route_target_info *route_info,
+			     struct sk_buff *skb) 
+{
+	if (route(skb, 0, route_info)!=1)
+		return NF_DROP;
+
+	if (route_info->flags & IPT_ROUTE_CONTINUE)
+		return IPT_CONTINUE;
+
+	ip_direct_send(skb);
+	return NF_STOLEN;
+}
+
+
+/* To detect and deter routed packet loopback when using the --tee option,
+ * we take a page out of the raw.patch book: on the copied skb, we set up
+ * a fake ->nfct entry, pointing to the local &route_tee_track. We skip
+ * routing packets when we see they already have that ->nfct.
+ */
+
+static struct ip_conntrack route_tee_track;
+
+static unsigned int ipt_route_target(struct sk_buff **pskb,
+				     const struct net_device *in,
+				     const struct net_device *out,
+				     unsigned int hooknum,
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,17)
+				     const struct xt_target *target,
+#endif
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
+				     const void *targinfo,
+				     void *userinfo)
+#else
+				     const void *targinfo)
+#endif
+{
+	const struct ipt_route_target_info *route_info = targinfo;
+	struct sk_buff *skb = *pskb;
+	unsigned int res;
+
+	if (skb->nfct == &route_tee_track.ct_general) {
+		/* Loopback - a packet we already routed, is to be
+		 * routed another time. Avoid that, now.
+		 */
+		if (net_ratelimit()) 
+			DEBUGP(KERN_DEBUG "ipt_ROUTE: loopback - DROP!\n");
+		return NF_DROP;
+	}
+
+	/* If we are at PREROUTING or INPUT hook
+	 * the TTL isn't decreased by the IP stack
+	 */
+	if (hooknum == NF_IP_PRE_ROUTING ||
+	    hooknum == NF_IP_LOCAL_IN) {
+
+		struct iphdr *iph = skb->nh.iph;
+
+		if (iph->ttl <= 1) {
+			struct rtable *rt;
+			struct flowi fl = {
+				.oif = 0,
+				.nl_u = {
+					.ip4_u = {
+						.daddr = iph->daddr,
+						.saddr = iph->saddr,
+						.tos = RT_TOS(iph->tos),
+						.scope = ((iph->tos & RTO_ONLINK) ?
+							  RT_SCOPE_LINK :
+							  RT_SCOPE_UNIVERSE)
+					}
+				} 
+			};
+
+			if (ip_route_output_key(&rt, &fl)) {
+				return NF_DROP;
+			}
+
+			if (skb->dev == rt->u.dst.dev) {
+				/* Drop old route. */
+				dst_release(skb->dst);
+				skb->dst = &rt->u.dst;
+
+				/* this will traverse normal stack, and 
+				 * thus call conntrack on the icmp packet */
+				icmp_send(skb, ICMP_TIME_EXCEEDED, 
+					  ICMP_EXC_TTL, 0);
+			}
+
+			return NF_DROP;
+		}
+
+		/*
+		 * If we are at INPUT the checksum must be recalculated since
+		 * the length could change as the result of a defragmentation.
+		 */
+		if(hooknum == NF_IP_LOCAL_IN) {
+			iph->ttl = iph->ttl - 1;
+			iph->check = 0;
+			iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
+		} else {
+			ip_decrease_ttl(iph);
+		}
+	}
+
+	if ((route_info->flags & IPT_ROUTE_TEE)) {
+		/*
+		 * Copy the *pskb, and route the copy. Will later return
+		 * IPT_CONTINUE for the original skb, which should continue
+		 * on its way as if nothing happened. The copy should be
+		 * independantly delivered to the ROUTE --gw.
+		 */
+		skb = skb_copy(*pskb, GFP_ATOMIC);
+		if (!skb) {
+			if (net_ratelimit()) 
+				DEBUGP(KERN_DEBUG "ipt_ROUTE: copy failed!\n");
+			return IPT_CONTINUE;
+		}
+	}
+
+	/* Tell conntrack to forget this packet since it may get confused 
+	 * when a packet is leaving with dst address == our address.
+	 * Good idea ? Dunno. Need advice.
+	 *
+	 * NEW: mark the skb with our &route_tee_track, so we avoid looping
+	 * on any already routed packet.
+	 */
+	if (!(route_info->flags & IPT_ROUTE_CONTINUE)) {
+		nf_conntrack_put(skb->nfct);
+		skb->nfct = &route_tee_track.ct_general;
+		skb->nfctinfo = IP_CT_NEW;
+		nf_conntrack_get(skb->nfct);
+	}
+
+	if (route_info->oif[0] != '\0') {
+		res = route_oif(route_info, skb);
+	} else if (route_info->iif[0] != '\0') {
+		res = route_iif(route_info, skb);
+	} else if (route_info->gw) {
+		res = route_gw(route_info, skb);
+	} else {
+		if (net_ratelimit()) 
+			DEBUGP(KERN_DEBUG "ipt_ROUTE: no parameter !\n");
+		res = IPT_CONTINUE;
+	}
+
+	if ((route_info->flags & IPT_ROUTE_TEE))
+		res = IPT_CONTINUE;
+
+	return res;
+}
+
+
+static int ipt_route_checkentry(const char *tablename,
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
+				const void *e,
+#else
+				const struct ipt_ip *ip,
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,17)