exthdrs.c

linux 内核源代码

	 */

	n = hdr->hdrlen >> 1;

	if (hdr->segments_left > n) {
		IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
				 IPSTATS_MIB_INHDRERRORS);
		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
				  ((&hdr->segments_left) -
				   skb_network_header(skb)));
		return -1;
	}

	/* We are about to mangle packet header. Be careful!
	   Do not damage packets queued somewhere.
	 */
	if (skb_cloned(skb)) {
		/* the copy is a forwarded packet */
		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
			IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
					 IPSTATS_MIB_OUTDISCARDS);
			kfree_skb(skb);
			return -1;
		}
		hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
	}

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

	i = n - --hdr->segments_left;

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

	switch (hdr->type) {
#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
	case IPV6_SRCRT_TYPE_2:
		if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
				     (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
				     IPPROTO_ROUTING) < 0) {
			IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
					 IPSTATS_MIB_INADDRERRORS);
			kfree_skb(skb);
			return -1;
		}
		if (!ipv6_chk_home_addr(addr)) {
			IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
					 IPSTATS_MIB_INADDRERRORS);
			kfree_skb(skb);
			return -1;
		}
		break;
#endif
	default:
		break;
	}

	if (ipv6_addr_is_multicast(addr)) {
		IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
				 IPSTATS_MIB_INADDRERRORS);
		kfree_skb(skb);
		return -1;
	}

	ipv6_addr_copy(&daddr, addr);
	ipv6_addr_copy(addr, &ipv6_hdr(skb)->daddr);
	ipv6_addr_copy(&ipv6_hdr(skb)->daddr, &daddr);

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

	if (skb->dst->dev->flags&IFF_LOOPBACK) {
		if (ipv6_hdr(skb)->hop_limit <= 1) {
			IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
					 IPSTATS_MIB_INHDRERRORS);
			icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
				    0, skb->dev);
			kfree_skb(skb);
			return -1;
		}
		ipv6_hdr(skb)->hop_limit--;
		goto looped_back;
	}

	skb_push(skb, skb->data - skb_network_header(skb));
	dst_input(skb);
	return -1;

unknown_rh:
	IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
			  (&hdr->type) - skb_network_header(skb));
	return -1;
}

static struct inet6_protocol rthdr_protocol = {
	.handler	=	ipv6_rthdr_rcv,
	.flags		=	INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
};

void __init ipv6_rthdr_init(void)
{
	if (inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING) < 0)
		printk(KERN_ERR "ipv6_rthdr_init: Could not register protocol\n");
};

/**********************************
  Hop-by-hop options.
 **********************************/

/*
 * Note: we cannot rely on skb->dst before we assign it in ip6_route_input().
 */
static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
{
	return skb->dst ? ip6_dst_idev(skb->dst) : __in6_dev_get(skb->dev);
}

/* Router Alert as of RFC 2711 */

static int ipv6_hop_ra(struct sk_buff *skb, int optoff)
{
	const unsigned char *nh = skb_network_header(skb);

	if (nh[optoff + 1] == 2) {
		IP6CB(skb)->ra = optoff;
		return 1;
	}
	LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
		       nh[optoff + 1]);
	kfree_skb(skb);
	return 0;
}

/* Jumbo payload */

static int ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
{
	const unsigned char *nh = skb_network_header(skb);
	u32 pkt_len;

	if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
		LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
			       nh[optoff+1]);
		IP6_INC_STATS_BH(ipv6_skb_idev(skb),
				 IPSTATS_MIB_INHDRERRORS);
		goto drop;
	}

	pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
	if (pkt_len <= IPV6_MAXPLEN) {
		IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS);
		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
		return 0;
	}
	if (ipv6_hdr(skb)->payload_len) {
		IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS);
		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
		return 0;
	}

	if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
		IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INTRUNCATEDPKTS);
		goto drop;
	}

	if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
		goto drop;

	return 1;

drop:
	kfree_skb(skb);
	return 0;
}

static struct tlvtype_proc tlvprochopopt_lst[] = {
	{
		.type	= IPV6_TLV_ROUTERALERT,
		.func	= ipv6_hop_ra,
	},
	{
		.type	= IPV6_TLV_JUMBO,
		.func	= ipv6_hop_jumbo,
	},
	{ -1, }
};

int ipv6_parse_hopopts(struct sk_buff *skb)
{
	struct inet6_skb_parm *opt = IP6CB(skb);

	/*
	 * skb_network_header(skb) is equal to skb->data, and
	 * skb_network_header_len(skb) is always equal to
	 * sizeof(struct ipv6hdr) by definition of
	 * hop-by-hop options.
	 */
	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
	    !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
				 ((skb_transport_header(skb)[1] + 1) << 3)))) {
		kfree_skb(skb);
		return -1;
	}

	opt->hop = sizeof(struct ipv6hdr);
	if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
		skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
		opt = IP6CB(skb);
		opt->nhoff = sizeof(struct ipv6hdr);
		return 1;
	}
	return -1;
}

/*
 *	Creating outbound headers.
 *
 *	"build" functions work when skb is filled from head to tail (datagram)
 *	"push"	functions work when headers are added from tail to head (tcp)
 *
 *	In both cases we assume, that caller reserved enough room
 *	for headers.
 */

static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
			    struct ipv6_rt_hdr *opt,
			    struct in6_addr **addr_p)
{
	struct rt0_hdr *phdr, *ihdr;
	int hops;

	ihdr = (struct rt0_hdr *) opt;

	phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
	memcpy(phdr, ihdr, sizeof(struct rt0_hdr));

	hops = ihdr->rt_hdr.hdrlen >> 1;

	if (hops > 1)
		memcpy(phdr->addr, ihdr->addr + 1,
		       (hops - 1) * sizeof(struct in6_addr));

	ipv6_addr_copy(phdr->addr + (hops - 1), *addr_p);
	*addr_p = ihdr->addr;

	phdr->rt_hdr.nexthdr = *proto;
	*proto = NEXTHDR_ROUTING;
}

static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
{
	struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));

	memcpy(h, opt, ipv6_optlen(opt));
	h->nexthdr = *proto;
	*proto = type;
}

void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
			  u8 *proto,
			  struct in6_addr **daddr)
{
	if (opt->srcrt) {
		ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
		/*
		 * IPV6_RTHDRDSTOPTS is ignored
		 * unless IPV6_RTHDR is set (RFC3542).
		 */
		if (opt->dst0opt)
			ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
	}
	if (opt->hopopt)
		ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
}

EXPORT_SYMBOL(ipv6_push_nfrag_opts);

void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
{
	if (opt->dst1opt)
		ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
}

struct ipv6_txoptions *
ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
{
	struct ipv6_txoptions *opt2;

	opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
	if (opt2) {
		long dif = (char*)opt2 - (char*)opt;
		memcpy(opt2, opt, opt->tot_len);
		if (opt2->hopopt)
			*((char**)&opt2->hopopt) += dif;
		if (opt2->dst0opt)
			*((char**)&opt2->dst0opt) += dif;
		if (opt2->dst1opt)
			*((char**)&opt2->dst1opt) += dif;
		if (opt2->srcrt)
			*((char**)&opt2->srcrt) += dif;
	}
	return opt2;
}

EXPORT_SYMBOL_GPL(ipv6_dup_options);

static int ipv6_renew_option(void *ohdr,
			     struct ipv6_opt_hdr __user *newopt, int newoptlen,
			     int inherit,
			     struct ipv6_opt_hdr **hdr,
			     char **p)
{
	if (inherit) {
		if (ohdr) {
			memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
			*hdr = (struct ipv6_opt_hdr *)*p;
			*p += CMSG_ALIGN(ipv6_optlen(*(struct ipv6_opt_hdr **)hdr));
		}
	} else {
		if (newopt) {
			if (copy_from_user(*p, newopt, newoptlen))
				return -EFAULT;
			*hdr = (struct ipv6_opt_hdr *)*p;
			if (ipv6_optlen(*(struct ipv6_opt_hdr **)hdr) > newoptlen)
				return -EINVAL;
			*p += CMSG_ALIGN(newoptlen);
		}
	}
	return 0;
}

struct ipv6_txoptions *
ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
		   int newtype,
		   struct ipv6_opt_hdr __user *newopt, int newoptlen)
{
	int tot_len = 0;
	char *p;
	struct ipv6_txoptions *opt2;
	int err;

	if (opt) {
		if (newtype != IPV6_HOPOPTS && opt->hopopt)
			tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
		if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
			tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
		if (newtype != IPV6_RTHDR && opt->srcrt)
			tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
		if (newtype != IPV6_DSTOPTS && opt->dst1opt)
			tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
	}

	if (newopt && newoptlen)
		tot_len += CMSG_ALIGN(newoptlen);

	if (!tot_len)
		return NULL;

	tot_len += sizeof(*opt2);
	opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
	if (!opt2)
		return ERR_PTR(-ENOBUFS);

	memset(opt2, 0, tot_len);

	opt2->tot_len = tot_len;
	p = (char *)(opt2 + 1);

	err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
				newtype != IPV6_HOPOPTS,
				&opt2->hopopt, &p);
	if (err)
		goto out;

	err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
				newtype != IPV6_RTHDRDSTOPTS,
				&opt2->dst0opt, &p);
	if (err)
		goto out;

	err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
				newtype != IPV6_RTHDR,
				(struct ipv6_opt_hdr **)&opt2->srcrt, &p);
	if (err)
		goto out;

	err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
				newtype != IPV6_DSTOPTS,
				&opt2->dst1opt, &p);
	if (err)
		goto out;

	opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
			  (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
			  (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
	opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);

	return opt2;
out:
	sock_kfree_s(sk, opt2, opt2->tot_len);
	return ERR_PTR(err);
}

struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
					  struct ipv6_txoptions *opt)
{
	/*
	 * ignore the dest before srcrt unless srcrt is being included.
	 * --yoshfuji
	 */
	if (opt && opt->dst0opt && !opt->srcrt) {
		if (opt_space != opt) {
			memcpy(opt_space, opt, sizeof(*opt_space));
			opt = opt_space;
		}
		opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
		opt->dst0opt = NULL;
	}

	return opt;
}