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linux/net/ipv6/ip6_input.c
Jesse Gross 75f2811c64 ipv6: Add fragment reporting to ipv6_skip_exthdr(). 
While parsing through IPv6 extension headers, fragment headers are
skipped making them invisible to the caller.  This reports the
fragment offset of the last header in order to make it possible to
determine whether the packet is fragmented and, if so whether it is
a first or last fragment.

Signed-off-by: Jesse Gross <jesse@nicira.com>
2011-12-03 09:35:10 -08:00

345 lines
7.9 KiB
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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;
__be16 frag_off;
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, &frag_off);
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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