[IPV6] MIP6: Add routing header type 2 transformation.

Add routing header type 2 transformation for Mobile IPv6.
Based on MIPL2 kernel patch.
Signed-off-by: Noriaki TAKAMIYA <takamiya@po.ntts.co.jp>
Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/mip6.h

+/*
+ * Copyright (C)2003-2006 Helsinki University of Technology
+ * Copyright (C)2003-2006 USAGI/WIDE Project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+/*
+ * Authors:
+ *	Noriaki TAKAMIYA @USAGI
+ *	Masahide NAKAMURA @USAGI
+ *	YOSHIFUJI Hideaki @USAGI
+ */
+#ifndef _NET_MIP6_H
+#define _NET_MIP6_H
+
+extern int mip6_init(void);
+extern void mip6_fini(void);
+
+#endif

net/ipv6/Makefile

@@ -14,6 +14,8 @@ ipv6-$(CONFIG_XFRM) += xfrm6_policy.o xfrm6_state.o xfrm6_input.o \
 	xfrm6_output.o
 ipv6-$(CONFIG_NETFILTER) += netfilter.o
 ipv6-$(CONFIG_IPV6_MULTIPLE_TABLES) += fib6_rules.o
+ipv6-$(CONFIG_IPV6_MIP6) += mip6.o
+
 ipv6-objs += $(ipv6-y)
 
 obj-$(CONFIG_INET6_AH) += ah6.o

net/ipv6/af_inet6.c

@@ -59,6 +59,9 @@
 #ifdef CONFIG_IPV6_TUNNEL
 #include <net/ip6_tunnel.h>
 #endif
+#ifdef CONFIG_IPV6_MIP6
+#include <net/mip6.h>
+#endif
 
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -857,6 +860,9 @@ static int __init inet6_init(void)
 	ipv6_frag_init();
 	ipv6_nodata_init();
 	ipv6_destopt_init();
+#ifdef CONFIG_IPV6_MIP6
+	mip6_init();
+#endif
 
 	/* Init v6 transport protocols. */
 	udpv6_init();
@@ -919,6 +925,9 @@ static void __exit inet6_exit(void)
  	udp6_proc_exit();
  	tcp6_proc_exit();
  	raw6_proc_exit();
+#endif
+#ifdef CONFIG_IPV6_MIP6
+	mip6_fini();
 #endif
 	/* Cleanup code parts. */
 	sit_cleanup();

net/ipv6/mip6.c

+/*
+ * Copyright (C)2003-2006 Helsinki University of Technology
+ * Copyright (C)2003-2006 USAGI/WIDE Project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+/*
+ * Authors:
+ *	Noriaki TAKAMIYA @USAGI
+ *	Masahide NAKAMURA @USAGI
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ipv6.h>
+#include <net/ipv6.h>
+#include <net/xfrm.h>
+#include <net/mip6.h>
+
+static xfrm_address_t *mip6_xfrm_addr(struct xfrm_state *x, xfrm_address_t *addr)
+{
+	return x->coaddr;
+}
+
+static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+	struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
+
+	if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
+	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
+		return -ENOENT;
+
+	return rt2->rt_hdr.nexthdr;
+}
+
+/* Routing Header type 2 is inserted.
+ * IP Header's dst address is replaced with Routing Header's Home Address.
+ */
+static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	struct ipv6hdr *iph;
+	struct rt2_hdr *rt2;
+	u8 nexthdr;
+
+	iph = (struct ipv6hdr *)skb->data;
+	iph->payload_len = htons(skb->len - sizeof(*iph));
+
+	nexthdr = *skb->nh.raw;
+	*skb->nh.raw = IPPROTO_ROUTING;
+
+	rt2 = (struct rt2_hdr *)skb->h.raw;
+	rt2->rt_hdr.nexthdr = nexthdr;
+	rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
+	rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
+	rt2->rt_hdr.segments_left = 1;
+	memset(&rt2->reserved, 0, sizeof(rt2->reserved));
+
+	BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
+
+	memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
+	memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
+
+	return 0;
+}
+
+static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
+			     u8 **nexthdr)
+{
+	u16 offset = sizeof(struct ipv6hdr);
+	struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
+	unsigned int packet_len = skb->tail - skb->nh.raw;
+	int found_rhdr = 0;
+
+	*nexthdr = &skb->nh.ipv6h->nexthdr;
+
+	while (offset + 1 <= packet_len) {
+
+		switch (**nexthdr) {
+		case NEXTHDR_HOP:
+			break;
+		case NEXTHDR_ROUTING:
+			if (offset + 3 <= packet_len) {
+				struct ipv6_rt_hdr *rt;
+				rt = (struct ipv6_rt_hdr *)(skb->nh.raw + offset);
+				if (rt->type != 0)
+					return offset;
+			}
+			found_rhdr = 1;
+			break;
+		case NEXTHDR_DEST:
+			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
+				return offset;
+
+			if (found_rhdr)
+				return offset;
+
+			break;
+		default:
+			return offset;
+		}
+
+		offset += ipv6_optlen(exthdr);
+		*nexthdr = &exthdr->nexthdr;
+		exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
+	}
+
+	return offset;
+}
+
+static int mip6_rthdr_init_state(struct xfrm_state *x)
+{
+	if (x->id.spi) {
+		printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
+		       x->id.spi);
+		return -EINVAL;
+	}
+	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
+		printk(KERN_INFO "%s: state's mode is not %u: %u\n",
+		       __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
+		return -EINVAL;
+	}
+
+	x->props.header_len = sizeof(struct rt2_hdr);
+
+	return 0;
+}
+
+/*
+ * Do nothing about destroying since it has no specific operation for routing
+ * header type 2 unlike IPsec protocols.
+ */
+static void mip6_rthdr_destroy(struct xfrm_state *x)
+{
+}
+
+static struct xfrm_type mip6_rthdr_type =
+{
+	.description	= "MIP6RT",
+	.owner		= THIS_MODULE,
+	.proto	     	= IPPROTO_ROUTING,
+	.flags		= XFRM_TYPE_NON_FRAGMENT,
+	.init_state	= mip6_rthdr_init_state,
+	.destructor	= mip6_rthdr_destroy,
+	.input		= mip6_rthdr_input,
+	.output		= mip6_rthdr_output,
+	.hdr_offset	= mip6_rthdr_offset,
+	.remote_addr	= mip6_xfrm_addr,
+};
+
+int __init mip6_init(void)
+{
+	printk(KERN_INFO "Mobile IPv6\n");
+
+	if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
+		printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
+		goto mip6_rthdr_xfrm_fail;
+	}
+	return 0;
+
+ mip6_rthdr_xfrm_fail:
+	return -EAGAIN;
+}
+
+void __exit mip6_fini(void)
+{
+	if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
+		printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
+}