linux/net/ipv6/netfilter.c
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   1#include <linux/kernel.h>
   2#include <linux/init.h>
   3#include <linux/ipv6.h>
   4#include <linux/netfilter.h>
   5#include <linux/netfilter_ipv6.h>
   6#include <linux/export.h>
   7#include <net/dst.h>
   8#include <net/ipv6.h>
   9#include <net/ip6_route.h>
  10#include <net/xfrm.h>
  11#include <net/ip6_checksum.h>
  12#include <net/netfilter/nf_queue.h>
  13
  14int ip6_route_me_harder(struct sk_buff *skb)
  15{
  16        struct net *net = dev_net(skb_dst(skb)->dev);
  17        const struct ipv6hdr *iph = ipv6_hdr(skb);
  18        struct dst_entry *dst;
  19        struct flowi6 fl6 = {
  20                .flowi6_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
  21                .flowi6_mark = skb->mark,
  22                .daddr = iph->daddr,
  23                .saddr = iph->saddr,
  24        };
  25
  26        dst = ip6_route_output(net, skb->sk, &fl6);
  27        if (dst->error) {
  28                IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  29                LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
  30                dst_release(dst);
  31                return -EINVAL;
  32        }
  33
  34        /* Drop old route. */
  35        skb_dst_drop(skb);
  36
  37        skb_dst_set(skb, dst);
  38
  39#ifdef CONFIG_XFRM
  40        if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  41            xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
  42                skb_dst_set(skb, NULL);
  43                dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0);
  44                if (IS_ERR(dst))
  45                        return -1;
  46                skb_dst_set(skb, dst);
  47        }
  48#endif
  49
  50        return 0;
  51}
  52EXPORT_SYMBOL(ip6_route_me_harder);
  53
  54/*
  55 * Extra routing may needed on local out, as the QUEUE target never
  56 * returns control to the table.
  57 */
  58
  59struct ip6_rt_info {
  60        struct in6_addr daddr;
  61        struct in6_addr saddr;
  62        u_int32_t mark;
  63};
  64
  65static void nf_ip6_saveroute(const struct sk_buff *skb,
  66                             struct nf_queue_entry *entry)
  67{
  68        struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  69
  70        if (entry->hook == NF_INET_LOCAL_OUT) {
  71                const struct ipv6hdr *iph = ipv6_hdr(skb);
  72
  73                rt_info->daddr = iph->daddr;
  74                rt_info->saddr = iph->saddr;
  75                rt_info->mark = skb->mark;
  76        }
  77}
  78
  79static int nf_ip6_reroute(struct sk_buff *skb,
  80                          const struct nf_queue_entry *entry)
  81{
  82        struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  83
  84        if (entry->hook == NF_INET_LOCAL_OUT) {
  85                const struct ipv6hdr *iph = ipv6_hdr(skb);
  86                if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  87                    !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  88                    skb->mark != rt_info->mark)
  89                        return ip6_route_me_harder(skb);
  90        }
  91        return 0;
  92}
  93
  94static int nf_ip6_route(struct net *net, struct dst_entry **dst,
  95                        struct flowi *fl, bool strict)
  96{
  97        static const struct ipv6_pinfo fake_pinfo;
  98        static const struct inet_sock fake_sk = {
  99                /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
 100                .sk.sk_bound_dev_if = 1,
 101                .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
 102        };
 103        const void *sk = strict ? &fake_sk : NULL;
 104        struct dst_entry *result;
 105        int err;
 106
 107        result = ip6_route_output(net, sk, &fl->u.ip6);
 108        err = result->error;
 109        if (err)
 110                dst_release(result);
 111        else
 112                *dst = result;
 113        return err;
 114}
 115
 116__sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
 117                             unsigned int dataoff, u_int8_t protocol)
 118{
 119        const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 120        __sum16 csum = 0;
 121
 122        switch (skb->ip_summed) {
 123        case CHECKSUM_COMPLETE:
 124                if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 125                        break;
 126                if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 127                                     skb->len - dataoff, protocol,
 128                                     csum_sub(skb->csum,
 129                                              skb_checksum(skb, 0,
 130                                                           dataoff, 0)))) {
 131                        skb->ip_summed = CHECKSUM_UNNECESSARY;
 132                        break;
 133                }
 134                /* fall through */
 135        case CHECKSUM_NONE:
 136                skb->csum = ~csum_unfold(
 137                                csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 138                                             skb->len - dataoff,
 139                                             protocol,
 140                                             csum_sub(0,
 141                                                      skb_checksum(skb, 0,
 142                                                                   dataoff, 0))));
 143                csum = __skb_checksum_complete(skb);
 144        }
 145        return csum;
 146}
 147EXPORT_SYMBOL(nf_ip6_checksum);
 148
 149static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 150                                       unsigned int dataoff, unsigned int len,
 151                                       u_int8_t protocol)
 152{
 153        const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 154        __wsum hsum;
 155        __sum16 csum = 0;
 156
 157        switch (skb->ip_summed) {
 158        case CHECKSUM_COMPLETE:
 159                if (len == skb->len - dataoff)
 160                        return nf_ip6_checksum(skb, hook, dataoff, protocol);
 161                /* fall through */
 162        case CHECKSUM_NONE:
 163                hsum = skb_checksum(skb, 0, dataoff, 0);
 164                skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 165                                                         &ip6h->daddr,
 166                                                         skb->len - dataoff,
 167                                                         protocol,
 168                                                         csum_sub(0, hsum)));
 169                skb->ip_summed = CHECKSUM_NONE;
 170                return __skb_checksum_complete_head(skb, dataoff + len);
 171        }
 172        return csum;
 173};
 174
 175static const struct nf_afinfo nf_ip6_afinfo = {
 176        .family                 = AF_INET6,
 177        .checksum               = nf_ip6_checksum,
 178        .checksum_partial       = nf_ip6_checksum_partial,
 179        .route                  = nf_ip6_route,
 180        .saveroute              = nf_ip6_saveroute,
 181        .reroute                = nf_ip6_reroute,
 182        .route_key_size         = sizeof(struct ip6_rt_info),
 183};
 184
 185int __init ipv6_netfilter_init(void)
 186{
 187        return nf_register_afinfo(&nf_ip6_afinfo);
 188}
 189
 190/* This can be called from inet6_init() on errors, so it cannot
 191 * be marked __exit. -DaveM
 192 */
 193void ipv6_netfilter_fini(void)
 194{
 195        nf_unregister_afinfo(&nf_ip6_afinfo);
 196}
 197
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