path: root/net/ipv6/exthdrs.c

/*
 *	Extension Header handling for IPv6
 *	Linux INET6 implementation
 *
 *	Authors:
 *	Pedro Roque		<roque@di.fc.ul.pt>
 *	Andi Kleen		<ak@muc.de>
 *	Alexey Kuznetsov	<kuznet@ms2.inr.ac.ru>
 *
 *	$Id: exthdrs.c,v 1.13 2001/06/19 15:58:56 davem Exp $
 *
 *	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.
 */

/* Changes:
 *	yoshfuji		: ensure not to overrun while parsing
 *				  tlv options.
 *	Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs().
 *	YOSHIFUJI Hideaki @USAGI  Register inbound extension header
 *				  handlers as inet6_protocol{}.
 */

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/in6.h>
#include <linux/icmpv6.h>

#include <net/sock.h>
#include <net/snmp.h>

#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/transp_v6.h>
#include <net/rawv6.h>
#include <net/ndisc.h>
#include <net/ip6_route.h>
#include <net/addrconf.h>
#ifdef CONFIG_IPV6_MIP6
#include <net/xfrm.h>
#endif

#include <asm/uaccess.h>

int ipv6_find_tlv(struct sk_buff *skb, int offset, int type)
{
	const unsigned char *nh = skb_network_header(skb);
	int packet_len = skb->tail - nh;
	struct ipv6_opt_hdr *hdr;
	int len;

	if (offset + 2 > packet_len)
		goto bad;
	hdr = (struct ipv6_opt_hdr *)(nh + offset);
	len = ((hdr->hdrlen + 1) << 3);

	if (offset + len > packet_len)
		goto bad;

	offset += 2;
	len -= 2;

	while (len > 0) {
		int opttype = nh[offset];
		int optlen;

		if (opttype == type)
			return offset;

		switch (opttype) {
		case IPV6_TLV_PAD0:
			optlen = 1;
			break;
		default:
			optlen = nh[offset + 1] + 2;
			if (optlen > len)
				goto bad;
			break;
		}
		offset += optlen;
		len -= optlen;
	}
	/* not_found */
 bad:
	return -1;
}

/*
 *	Parsing tlv encoded headers.
 *
 *	Parsing function "func" returns 1, if parsing succeed
 *	and 0, if it failed.
 *	It MUST NOT touch skb->h.
 */

struct tlvtype_proc {
	int	type;
	int	(*func)(struct sk_buff **skbp, int offset);
};

/*********************
  Generic functions
 *********************/

/* An unknown option is detected, decide what to do */

static int ip6_tlvopt_unknown(struct sk_buff **skbp, int optoff)
{
	struct sk_buff *skb = *skbp;

	switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
	case 0: /* ignore */
		return 1;

	case 1: /* drop packet */
		break;

	case 3: /* Send ICMP if not a multicast address and drop packet */
		/* Actually, it is redundant check. icmp_send
		   will recheck in any case.
		 */
		if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
			break;
	case 2: /* send ICMP PARM PROB regardless and drop packet */
		icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
		return 0;
	};

	kfree_skb(skb);
	return 0;
}

/* Parse tlv encoded option header (hop-by-hop or destination) */

static int ip6_parse_tlv(struct tlvtype_proc *procs, struct sk_buff **skbp)
{
	struct sk_buff *skb = *skbp;
	struct tlvtype_proc *curr;
	const unsigned char *nh = skb_network_header(skb);
	int off = skb->h.raw - skb->nh.raw;
	int len = (skb_transport_header(skb)[1] + 1) << 3;

	if (skb_transport_offset(skb) + len > skb_headlen(skb))
		goto bad;

	off += 2;
	len -= 2;

	while (len > 0) {
		int optlen = nh[off + 1] + 2;

		switch (nh[off]) {
		case IPV6_TLV_PAD0:
			optlen = 1;
			break;

		case IPV6_TLV_PADN:
			break;

		default: /* Other TLV code so scan list */
			if (optlen > len)
				goto bad;
			for (curr=procs; curr->type >= 0; curr++) {
				if (curr->type == nh[off]) {
					/* type specific length/alignment
					   checks will be performed in the
					   func(). */
					if (curr->func(skbp, off) == 0)
						return 0;
					break;
				}
			}
			if (curr->type < 0) {
				if