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/*
* IPv6 input
* Linux INET6 implementation
*
* Authors:
* Pedro Roque <roque@di.fc.ul.pt>
* Ian P. Morris <I.P.Morris@soton.ac.uk>
*
* Based in linux/net/ipv4/ip_input.c
*
* 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
*
* Mitsuru KANDA @USAGI and
* YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
*/

#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 <linux/mroute6.h>
#include <linux/slab.h>

#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.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 <net/xfrm.h>



inline int ip6_rcv_finish( struct sk_buff *skb)
{
if (skb_dst(skb) == NULL)
ip6_route_input(skb);

return dst_input(skb);
}

int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
const struct ipv6hdr *hdr;
u32 pkt_len;
struct inet6_dev *idev;
struct net *net = dev_net(skb->dev);

if (skb->pkt_type == PACKET_OTHERHOST) {
kfree_skb(skb);
return NET_RX_DROP;
}

rcu_read_lock();

idev = __in6_dev_get(skb->dev);

IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len);

if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
!idev || unlikely(idev->cnf.disable_ipv6)) {
IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
goto drop;
}

memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));

/*
* Store incoming device index. When the packet will
* be queued, we cannot refer to skb->dev anymore.
*
* BTW, when we send a packet for our own local address on a
* non-loopback interface (e.g. ethX), it is being delivered
* via the loopback interface (lo) here; skb->dev = loopback_dev.
* It, however, should be considered as if it is being
* arrived via the sending interface (ethX), because of the
* nature of scoping architecture. --yoshfuji
*/
IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;

if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
goto err;

hdr = ipv6_hdr(skb);

if (hdr->version != 6)
goto err;

/*
* RFC4291 2.5.3
* A packet received on an interface with a destination address
* of loopback must be dropped.
*/
if (!(dev->flags & IFF_LOOPBACK) &&
ipv6_addr_loopback(&hdr->daddr))
goto err;

/*
* RFC4291 2.7
* Multicast addresses must not be used as source addresses in IPv6
* packets or appear in any Routing header.
*/
if (ipv6_addr_is_multicast(&hdr->saddr))
goto err;

skb->transport_header = skb->network_header + sizeof(*hdr);
IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);

pkt_len = ntohs(hdr->payload_len);

/* pkt_len may be zero if Jumbo payload option is present */
if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
IP6_INC_STATS_BH(net,
idev, IPSTATS_MIB_INTRUNCATEDPKTS);
goto drop;
}
if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
goto drop;
}
hdr = ipv6_hdr(skb);
}

if (hdr->nexthdr == NEXTHDR_HOP) {
if (ipv6_parse_hopopts(skb) < 0) {
IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
rcu_read_unlock();
return NET_RX_DROP;
}
}

rcu_read_unlock();

/* Must drop socket now because of tproxy. */
skb_orphan(skb);

return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
ip6_rcv_finish);
err:
IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
drop:
rcu_read_unlock();
kfree_skb(skb);
return NET_RX_DROP;
}

/*
* Deliver the packet to the host
*/


static int ip6_input_finish(struct sk_buff *skb)
{
const struct inet6_protocol *ipprot;
unsigned int nhoff;
int nexthdr, raw;
u8 hash;
struct inet6_dev *idev;
struct net *net = dev_net(skb_dst(skb)->dev);

/*
* Parse extension headers
*/

rcu_read_lock();
resubmit:
idev = ip6_dst_idev(skb_dst(skb));
if (!pskb_pull(skb, skb_transport_offset(skb)))
goto discard;
nhoff = IP6CB(skb)->nhoff;
nexthdr = skb_network_header(skb)[nhoff];

raw = raw6_local_deliver(skb, nexthdr);

hash = nexthdr & (MAX_INET_PROTOS - 1);
if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
int ret;

if (ipprot->flags & INET6_PROTO_FINAL) {
const struct ipv6hdr *hdr;

/* Free reference early: we don't need it any more,
and it may hold ip_conntrack module loaded
indefinitely. */
nf_reset(skb);

skb_postpull_rcsum(skb, skb_network_header(skb),
skb_network_header_len(skb));
hdr = ipv6_hdr(skb);
if (ipv6_addr_is_multicast(&hdr->daddr) &&
!ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
&hdr->saddr) &&
!ipv6_is_mld(skb, nexthdr))
goto discard;
}
if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
goto discard;

ret = ipprot->handler(skb);
if (ret > 0)
goto resubmit;
else if (ret == 0)
IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
} else {
if (!raw) {
if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
IP6_INC_STATS_BH(net, idev,
IPSTATS_MIB_INUNKNOWNPROTOS);
icmpv6_send(skb, ICMPV6_PARAMPROB,
ICMPV6_UNK_NEXTHDR, nhoff);
}
} else
IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
kfree_skb(skb);
}
rcu_read_unlock();
return 0;

discard:
IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
rcu_read_unlock();
kfree_skb(skb);
return 0;
}


int ip6_input(struct sk_buff *skb)
{
return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
ip6_input_finish);
}

int ip6_mc_input(struct sk_buff *skb)
{
const struct ipv6hdr *hdr;
int deliver;

IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev),
ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
skb->len);

hdr = ipv6_hdr(skb);
deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);

#ifdef CONFIG_IPV6_MROUTE
/*
* IPv6 multicast router mode is now supported ;)
*/
if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
!(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
/*
* Okay, we try to forward - split and duplicate
* packets.
*/
struct sk_buff *skb2;
struct inet6_skb_parm *opt = IP6CB(skb);

/* Check for MLD */
if (unlikely(opt->ra)) {
/* Check if this is a mld message */
u8 *ptr = skb_network_header(skb) + opt->ra;
struct icmp6hdr *icmp6;
u8 nexthdr = hdr->nexthdr;
int offset;

/* Check if the value of Router Alert
* is for MLD (0x0000).
*/
if ((ptr[2] | ptr[3]) == 0) {
deliver = 0;

if (!ipv6_ext_hdr(nexthdr)) {
/* BUG */
goto out;
}
offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
&nexthdr);
if (offset < 0)
goto out;

if (nexthdr != IPPROTO_ICMPV6)
goto out;

if (!pskb_may_pull(skb, (skb_network_header(skb) +
offset + 1 - skb->data)))
goto out;

icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);

switch (icmp6->icmp6_type) {
case ICMPV6_MGM_QUERY:
case ICMPV6_MGM_REPORT:
case ICMPV6_MGM_REDUCTION:
case ICMPV6_MLD2_REPORT:
deliver = 1;
break;
}
goto out;
}
/* unknown RA - process it normally */
}

if (deliver)
skb2 = skb_clone(skb, GFP_ATOMIC);
else {
skb2 = skb;
skb = NULL;
}

if (skb2) {
ip6_mr_input(skb2);
}
}
out:
#endif
if (likely(deliver))
ip6_input(skb);
else {
/* discard */
kfree_skb(skb);
}

return 0;
}
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