exthdrs.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 653 行 · 第 1/2 页

/*
 *	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/sched.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>

#include <asm/uaccess.h>

/*
 *	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->nh.raw[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(&skb->nh.ipv6h->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;
	int off = skb->h.raw - skb->nh.raw;
	int len = ((skb->h.raw[1]+1)<<3);

	if ((skb->h.raw + len) - skb->data > skb_headlen(skb))
		goto bad;

	off += 2;
	len -= 2;

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

		switch (skb->nh.raw[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 == skb->nh.raw[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.
 *****************************/

static struct tlvtype_proc tlvprocdestopt_lst[] = {
	/* No destination options are defined now */
	{-1,			NULL}
};

static int ipv6_destopt_rcv(struct sk_buff **skbp, unsigned int *nhoffp)
{
	struct sk_buff *skb = *skbp;
	struct inet6_skb_parm *opt = IP6CB(skb);

	if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+8) ||
	    !pskb_may_pull(skb, (skb->h.raw-skb->data)+((skb->h.raw[1]+1)<<3))) {
		IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
		kfree_skb(skb);
		return -1;
	}

	opt->dst1 = skb->h.raw - skb->nh.raw;

	if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
		skb->h.raw += ((skb->h.raw[1]+1)<<3);
		*nhoffp = opt->dst1;
		return 1;
	}

	IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
	return -1;
}

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

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 **skbp, unsigned int *nhoffp)
{
	struct sk_buff *skb = *skbp;

	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 **skbp, unsigned int *nhoffp)
{
	struct sk_buff *skb = *skbp;
	struct inet6_skb_parm *opt = IP6CB(skb);
	struct in6_addr *addr;
	struct in6_addr daddr;
	int n, i;

	struct ipv6_rt_hdr *hdr;
	struct rt0_hdr *rthdr;

	if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+8) ||
	    !pskb_may_pull(skb, (skb->h.raw-skb->data)+((skb->h.raw[1]+1)<<3))) {
		IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
		kfree_skb(skb);
		return -1;
	}

	hdr = (struct ipv6_rt_hdr *) skb->h.raw;

	if (ipv6_addr_is_multicast(&skb->nh.ipv6h->daddr) ||
	    skb->pkt_type != PACKET_HOST) {
		IP6_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS);
		kfree_skb(skb);
		return -1;
	}

looped_back:
	if (hdr->segments_left == 0) {
		opt->srcrt = skb->h.raw - skb->nh.raw;
		skb->h.raw += (hdr->hdrlen + 1) << 3;
		opt->dst0 = opt->dst1;
		opt->dst1 = 0;
		*nhoffp = (&hdr->nexthdr) - skb->nh.raw;
		return 1;
	}

	if (hdr->type != IPV6_SRCRT_TYPE_0) {
		IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) - skb->nh.raw);
		return -1;
	}
	
	if (hdr->hdrlen & 0x01) {
		IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->hdrlen) - skb->nh.raw);
		return -1;
	}

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

	n = hdr->hdrlen >> 1;

	if (hdr->segments_left > n) {
		IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->segments_left) - skb->nh.raw);
		return -1;
	}

	/* We are about to mangle packet header. Be careful!
	   Do not damage packets queued somewhere.
	 */
	if (skb_cloned(skb)) {
		struct sk_buff *skb2 = skb_copy(skb, GFP_ATOMIC);
		kfree_skb(skb);
		/* the copy is a forwarded packet */
		if (skb2 == NULL) {
			IP6_INC_STATS_BH(IPSTATS_MIB_OUTDISCARDS);	
			return -1;
		}
		*skbp = skb = skb2;
		opt = IP6CB(skb2);
		hdr = (struct ipv6_rt_hdr *) skb2->h.raw;
	}

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

	i = n - --hdr->segments_left;

	rthdr = (struct rt0_hdr *) hdr;
	addr = rthdr->addr;
	addr += i - 1;

	if (ipv6_addr_is_multicast(addr)) {
		IP6_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS);
		kfree_skb(skb);
		return -1;
	}

	ipv6_addr_copy(&daddr, addr);
	ipv6_addr_copy(addr, &skb->nh.ipv6h->daddr);
	ipv6_addr_copy(&skb->nh.ipv6h->daddr, &daddr);

	dst_release(xchg(&skb->dst, NULL));
	ip6_route_input(skb);
	if (skb->dst->error) {
		skb_push(skb, skb->data - skb->nh.raw);
		dst_input(skb);
		return -1;
	}

	if (skb->dst->dev->flags&IFF_LOOPBACK) {
		if (skb->nh.ipv6h->hop_limit <= 1) {
			IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
			icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
				    0, skb->dev);
			kfree_skb(skb);