exthdrs.c

linux 内核源代码

/*
 *	Extension Header handling for IPv6
 *	Linux INET6 implementation
 *
 *	Authors:
 *	Pedro Roque		<[e-mail]>
 *	Andi Kleen		<[e-mail]>
 *	Alexey Kuznetsov	<[e-mail]>
 *
 *	$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>
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
#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 - skb->network_header;
	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;
}
EXPORT_SYMBOL_GPL(ipv6_find_tlv);

/*
 *	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 *skb, int offset);
};

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

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

static int ip6_tlvopt_unknown(struct sk_buff *skb, int optoff)
{
	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 *skb)
{
	struct tlvtype_proc *curr;
	const unsigned char *nh = skb_network_header(skb);
	int off = skb_network_header_len(skb);
	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(skb, off) == 0)
						return 0;
					break;
				}
			}
			if (curr->type < 0) {
				if (ip6_tlvopt_unknown(skb, off) == 0)
					return 0;
			}
			break;
		}
		off += optlen;
		len -= optlen;
	}
	if (len == 0)
		return 1;
bad:
	kfree_skb(skb);
	return 0;
}

/*****************************
  Destination options header.
 *****************************/

#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
static int ipv6_dest_hao(struct sk_buff *skb, int optoff)
{
	struct ipv6_destopt_hao *hao;
	struct inet6_skb_parm *opt = IP6CB(skb);
	struct ipv6hdr *ipv6h = ipv6_hdr(skb);
	struct in6_addr tmp_addr;
	int ret;

	if (opt->dsthao) {
		LIMIT_NETDEBUG(KERN_DEBUG "hao duplicated\n");
		goto discard;
	}
	opt->dsthao = opt->dst1;
	opt->dst1 = 0;

	hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);

	if (hao->length != 16) {
		LIMIT_NETDEBUG(
			KERN_DEBUG "hao invalid option length = %d\n", hao->length);
		goto discard;
	}

	if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
		LIMIT_NETDEBUG(
			KERN_DEBUG "hao is not an unicast addr: " NIP6_FMT "\n", NIP6(hao->addr));
		goto discard;
	}

	ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
			       (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
	if (unlikely(ret < 0))
		goto discard;

	if (skb_cloned(skb)) {
		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
			goto discard;

		/* update all variable using below by copied skbuff */
		hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
						  optoff);
		ipv6h = ipv6_hdr(skb);
	}

	if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->ip_summed = CHECKSUM_NONE;

	ipv6_addr_copy(&tmp_addr, &ipv6h->saddr);
	ipv6_addr_copy(&ipv6h->saddr, &hao->addr);
	ipv6_addr_copy(&hao->addr, &tmp_addr);

	if (skb->tstamp.tv64 == 0)
		__net_timestamp(skb);

	return 1;

 discard:
	kfree_skb(skb);
	return 0;
}
#endif

static struct tlvtype_proc tlvprocdestopt_lst[] = {
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
	{
		.type	= IPV6_TLV_HAO,
		.func	= ipv6_dest_hao,
	},
#endif
	{-1,			NULL}
};

static int ipv6_destopt_rcv(struct sk_buff *skb)
{
	struct inet6_skb_parm *opt = IP6CB(skb);
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
	__u16 dstbuf;
#endif
	struct dst_entry *dst;

	if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
	    !pskb_may_pull(skb, (skb_transport_offset(skb) +
				 ((skb_transport_header(skb)[1] + 1) << 3)))) {
		IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
				 IPSTATS_MIB_INHDRERRORS);
		kfree_skb(skb);
		return -1;
	}

	opt->lastopt = opt->dst1 = skb_network_header_len(skb);
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
	dstbuf = opt->dst1;
#endif

	dst = dst_clone(skb->dst);
	if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
		dst_release(dst);
		skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
		opt = IP6CB(skb);
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
		opt->nhoff = dstbuf;
#else
		opt->nhoff = opt->dst1;
#endif
		return 1;
	}

	IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
	dst_release(dst);
	return -1;
}

static struct inet6_protocol destopt_protocol = {
	.handler	=	ipv6_destopt_rcv,
	.flags		=	INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
};

void __init ipv6_destopt_init(void)
{
	if (inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS) < 0)
		printk(KERN_ERR "ipv6_destopt_init: Could not register protocol\n");
}

/********************************
  NONE header. No data in packet.
 ********************************/

static int ipv6_nodata_rcv(struct sk_buff *skb)
{
	kfree_skb(skb);
	return 0;
}

static struct inet6_protocol nodata_protocol = {
	.handler	=	ipv6_nodata_rcv,
	.flags		=	INET6_PROTO_NOPOLICY,
};

void __init ipv6_nodata_init(void)
{
	if (inet6_add_protocol(&nodata_protocol, IPPROTO_NONE) < 0)
		printk(KERN_ERR "ipv6_nodata_init: Could not register protocol\n");
}

/********************************
  Routing header.
 ********************************/

static int ipv6_rthdr_rcv(struct sk_buff *skb)
{
	struct inet6_skb_parm *opt = IP6CB(skb);
	struct in6_addr *addr = NULL;
	struct in6_addr daddr;
	struct inet6_dev *idev;
	int n, i;
	struct ipv6_rt_hdr *hdr;
	struct rt0_hdr *rthdr;
	int accept_source_route = ipv6_devconf.accept_source_route;

	idev = in6_dev_get(skb->dev);
	if (idev) {
		if (accept_source_route > idev->cnf.accept_source_route)
			accept_source_route = idev->cnf.accept_source_route;
		in6_dev_put(idev);
	}

	if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
	    !pskb_may_pull(skb, (skb_transport_offset(skb) +
				 ((skb_transport_header(skb)[1] + 1) << 3)))) {
		IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
				 IPSTATS_MIB_INHDRERRORS);
		kfree_skb(skb);
		return -1;
	}

	hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);

	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
	    skb->pkt_type != PACKET_HOST) {
		IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
				 IPSTATS_MIB_INADDRERRORS);
		kfree_skb(skb);
		return -1;
	}

looped_back:
	if (hdr->segments_left == 0) {
		switch (hdr->type) {
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
		case IPV6_SRCRT_TYPE_2:
			/* Silently discard type 2 header unless it was
			 * processed by own
			 */
			if (!addr) {
				IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
						 IPSTATS_MIB_INADDRERRORS);
				kfree_skb(skb);
				return -1;
			}
			break;
#endif
		default:
			break;
		}

		opt->lastopt = opt->srcrt = skb_network_header_len(skb);
		skb->transport_header += (hdr->hdrlen + 1) << 3;
		opt->dst0 = opt->dst1;
		opt->dst1 = 0;
		opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
		return 1;
	}

	switch (hdr->type) {
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
	case IPV6_SRCRT_TYPE_2:
		if (accept_source_route < 0)
			goto unknown_rh;
		/* Silently discard invalid RTH type 2 */
		if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
			IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
					 IPSTATS_MIB_INHDRERRORS);
			kfree_skb(skb);
			return -1;
		}
		break;
#endif
	default:
		goto unknown_rh;
	}

	/*
	 *	This is the routing header forwarding algorithm from
	 *	RFC 2460, page 16.