nf_conntrack_l3proto_ipv6.c

linux2.6.16版本

/*
 * Copyright (C)2004 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 version 2 as
 * published by the Free Software Foundation.
 *
 * Author:
 *	Yasuyuki Kozakai @USAGI <[e-mail]>
 *
 * 16 Dec 2003: Yasuyuki Kozakai @USAGI <[e-mail]>
 *	- support Layer 3 protocol independent connection tracking.
 *	  Based on the original ip_conntrack code which	had the following
 *	  copyright information:
 *		(C) 1999-2001 Paul `Rusty' Russell
 *		(C) 2002-2004 Netfilter Core Team <[e-mail]>
 *
 * 23 Mar 2004: Yasuyuki Kozakai @USAGI <[e-mail]>
 *	- add get_features() to support various size of conntrack
 *	  structures.
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/ipv6.h>
#include <linux/in6.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmp.h>
#include <linux/sysctl.h>
#include <net/ipv6.h>

#include <linux/netfilter_ipv6.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_protocol.h>
#include <net/netfilter/nf_conntrack_l3proto.h>
#include <net/netfilter/nf_conntrack_core.h>

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

DECLARE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat);

static int ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
			     struct nf_conntrack_tuple *tuple)
{
	u_int32_t _addrs[8], *ap;

	ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
				sizeof(_addrs), _addrs);
	if (ap == NULL)
		return 0;

	memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
	memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));

	return 1;
}

static int ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
			     const struct nf_conntrack_tuple *orig)
{
	memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
	memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));

	return 1;
}

static int ipv6_print_tuple(struct seq_file *s,
			    const struct nf_conntrack_tuple *tuple)
{
	return seq_printf(s, "src=" NIP6_FMT " dst=" NIP6_FMT " ",
			  NIP6(*((struct in6_addr *)tuple->src.u3.ip6)),
			  NIP6(*((struct in6_addr *)tuple->dst.u3.ip6)));
}

static int ipv6_print_conntrack(struct seq_file *s,
				const struct nf_conn *conntrack)
{
	return 0;
}

/*
 * Based on ipv6_skip_exthdr() in net/ipv6/exthdr.c
 *
 * This function parses (probably truncated) exthdr set "hdr"
 * of length "len". "nexthdrp" initially points to some place,
 * where type of the first header can be found.
 *
 * It skips all well-known exthdrs, and returns pointer to the start
 * of unparsable area i.e. the first header with unknown type.
 * if success, *nexthdr is updated by type/protocol of this header.
 *
 * NOTES: - it may return pointer pointing beyond end of packet,
 *          if the last recognized header is truncated in the middle.
 *        - if packet is truncated, so that all parsed headers are skipped,
 *          it returns -1.
 *        - if packet is fragmented, return pointer of the fragment header.
 *        - ESP is unparsable for now and considered like
 *          normal payload protocol.
 *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
 */

int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
			   int len)
{
	u8 nexthdr = *nexthdrp;

	while (ipv6_ext_hdr(nexthdr)) {
		struct ipv6_opt_hdr hdr;
		int hdrlen;

		if (len < (int)sizeof(struct ipv6_opt_hdr))
			return -1;
		if (nexthdr == NEXTHDR_NONE)
			break;
		if (nexthdr == NEXTHDR_FRAGMENT)
			break;
		if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
			BUG();
		if (nexthdr == NEXTHDR_AUTH)
			hdrlen = (hdr.hdrlen+2)<<2;
		else
			hdrlen = ipv6_optlen(&hdr);

		nexthdr = hdr.nexthdr;
		len -= hdrlen;
		start += hdrlen;
	}

	*nexthdrp = nexthdr;
	return start;
}

static int
ipv6_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
	     u_int8_t *protonum)
{
	unsigned int extoff;
	unsigned char pnum;
	int protoff;

	extoff = (u8*)((*pskb)->nh.ipv6h + 1) - (*pskb)->data;
	pnum = (*pskb)->nh.ipv6h->nexthdr;

	protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
					 (*pskb)->len - extoff);

	/*
	 * (protoff == (*pskb)->len) mean that the packet doesn't have no data
	 * except of IPv6 & ext headers. but it's tracked anyway. - YK
	 */
	if ((protoff < 0) || (protoff > (*pskb)->len)) {
		DEBUGP("ip6_conntrack_core: can't find proto in pkt\n");
		NF_CT_STAT_INC(error);
		NF_CT_STAT_INC(invalid);
		return -NF_ACCEPT;
	}

	*dataoff = protoff;
	*protonum = pnum;
	return NF_ACCEPT;
}

static u_int32_t ipv6_get_features(const struct nf_conntrack_tuple *tuple)
{
	return NF_CT_F_BASIC;
}

static unsigned int ipv6_confirm(unsigned int hooknum,
				 struct sk_buff **pskb,
				 const struct net_device *in,
				 const struct net_device *out,
				 int (*okfn)(struct sk_buff *))
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;

	/* This is where we call the helper: as the packet goes out. */
	ct = nf_ct_get(*pskb, &ctinfo);
	if (ct && ct->helper) {
		unsigned int ret, protoff;
		unsigned int extoff = (u8*)((*pskb)->nh.ipv6h + 1)
				      - (*pskb)->data;
		unsigned char pnum = (*pskb)->nh.ipv6h->nexthdr;

		protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
						 (*pskb)->len - extoff);
		if (protoff < 0 || protoff > (*pskb)->len ||
		    pnum == NEXTHDR_FRAGMENT) {
			DEBUGP("proto header not found\n");
			return NF_ACCEPT;
		}

		ret = ct->helper->help(pskb, protoff, ct, ctinfo);
		if (ret != NF_ACCEPT)
			return ret;
	}

	/* We've seen it coming out the other side: confirm it */

	return nf_conntrack_confirm(pskb);
}

extern struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb);
extern void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
			       struct net_device *in,
			       struct net_device *out,
			       int (*okfn)(struct sk_buff *));
static unsigned int ipv6_defrag(unsigned int hooknum,
				struct sk_buff **pskb,
				const struct net_device *in,
				const struct net_device *out,
				int (*okfn)(struct sk_buff *))
{
	struct sk_buff *reasm;

	/* Previously seen (loopback)?  */
	if ((*pskb)->nfct)
		return NF_ACCEPT;

	reasm = nf_ct_frag6_gather(*pskb);

	/* queued */
	if (reasm == NULL)
		return NF_STOLEN;

	/* error occured or not fragmented */
	if (reasm == *pskb)
		return NF_ACCEPT;

	nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
			   (struct net_device *)out, okfn);

	return NF_STOLEN;
}

static unsigned int ipv6_conntrack_in(unsigned int hooknum,
				      struct sk_buff **pskb,
				      const struct net_device *in,
				      const struct net_device *out,
				      int (*okfn)(struct sk_buff *))
{
	struct sk_buff *reasm = (*pskb)->nfct_reasm;

	/* This packet is fragmented and has reassembled packet. */
	if (reasm) {
		/* Reassembled packet isn't parsed yet ? */
		if (!reasm->nfct) {
			unsigned int ret;

			ret = nf_conntrack_in(PF_INET6, hooknum, &reasm);
			if (ret != NF_ACCEPT)
				return ret;
		}
		nf_conntrack_get(reasm->nfct);
		(*pskb)->nfct = reasm->nfct;
		return NF_ACCEPT;
	}

	return nf_conntrack_in(PF_INET6, hooknum, pskb);
}

static unsigned int ipv6_conntrack_local(unsigned int hooknum,
					 struct sk_buff **pskb,
					 const struct net_device *in,
					 const struct net_device *out,
					 int (*okfn)(struct sk_buff *))
{
	/* root is playing with raw sockets. */
	if ((*pskb)->len < sizeof(struct ipv6hdr)) {
		if (net_ratelimit())
			printk("ipv6_conntrack_local: packet too short\n");
		return NF_ACCEPT;
	}
	return ipv6_conntrack_in(hooknum, pskb, in, out, okfn);
}

/* Connection tracking may drop packets, but never alters them, so
   make it the first hook. */
static struct nf_hook_ops ipv6_conntrack_defrag_ops = {
	.hook		= ipv6_defrag,
	.owner		= THIS_MODULE,
	.pf		= PF_INET6,
	.hooknum	= NF_IP6_PRE_ROUTING,
	.priority	= NF_IP6_PRI_CONNTRACK_DEFRAG,
};

static struct nf_hook_ops ipv6_conntrack_in_ops = {
	.hook		= ipv6_conntrack_in,
	.owner		= THIS_MODULE,
	.pf		= PF_INET6,
	.hooknum	= NF_IP6_PRE_ROUTING,
	.priority	= NF_IP6_PRI_CONNTRACK,