net/ipv6/netfilter.c

   1 /*
   2  * IPv6 specific functions of netfilter core
   3  *
   4  * Rusty Russell (C) 2000 -- This code is GPL.
   5  * Patrick McHardy (C) 2006-2012
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/init.h>
   9 #include <linux/ipv6.h>
  10 #include <linux/netfilter.h>
  11 #include <linux/netfilter_ipv6.h>
  12 #include <linux/export.h>
  13 #include <net/addrconf.h>
  14 #include <net/dst.h>
  15 #include <net/ipv6.h>
  16 #include <net/ip6_route.h>
  17 #include <net/xfrm.h>
  18 #include <net/netfilter/nf_queue.h>
  19 #include <net/netfilter/nf_conntrack_bridge.h>
  20 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
  21 #include "../bridge/br_private.h"
  22
  23 int ip6_route_me_harder(struct net *net, struct sock *sk_partial, struct sk_buff *skb)
  24 {
  25         const struct ipv6hdr *iph = ipv6_hdr(skb);
  26         struct sock *sk = sk_to_full_sk(sk_partial);
  27         struct net_device *dev = skb_dst(skb)->dev;
  28         struct flow_keys flkeys;
  29         unsigned int hh_len;
  30         struct dst_entry *dst;
  31         int strict = (ipv6_addr_type(&iph->daddr) &
  32                       (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL));
  33         struct flowi6 fl6 = {
  34                 .flowi6_mark = skb->mark,
  35                 .flowi6_uid = sock_net_uid(net, sk),
  36                 .daddr = iph->daddr,
  37                 .saddr = iph->saddr,
  38         };
  39         int err;
  40
  41         if (sk && sk->sk_bound_dev_if)
  42                 fl6.flowi6_oif = sk->sk_bound_dev_if;
  43         else if (strict)
  44                 fl6.flowi6_oif = dev->ifindex;
  45         else
  46                 fl6.flowi6_oif = l3mdev_master_ifindex(dev);
  47
  48         fib6_rules_early_flow_dissect(net, skb, &fl6, &flkeys);
  49         dst = ip6_route_output(net, sk, &fl6);
  50         err = dst->error;
  51         if (err) {
  52                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  53                 net_dbg_ratelimited("ip6_route_me_harder: No more route\n");
  54                 dst_release(dst);
  55                 return err;
  56         }
  57
  58         /* Drop old route. */
  59         skb_dst_drop(skb);
  60
  61         skb_dst_set(skb, dst);
  62
  63 #ifdef CONFIG_XFRM
  64         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  65             xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
  66                 skb_dst_set(skb, NULL);
  67                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
  68                 if (IS_ERR(dst))
  69                         return PTR_ERR(dst);
  70                 skb_dst_set(skb, dst);
  71         }
  72 #endif
  73
  74         /* Change in oif may mean change in hh_len. */
  75         hh_len = skb_dst(skb)->dev->hard_header_len;
  76         if (skb_headroom(skb) < hh_len &&
  77             pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
  78                              0, GFP_ATOMIC))
  79                 return -ENOMEM;
  80
  81         return 0;
  82 }
  83 EXPORT_SYMBOL(ip6_route_me_harder);
  84
  85 static int nf_ip6_reroute(struct sk_buff *skb,
  86                           const struct nf_queue_entry *entry)
  87 {
  88         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  89
  90         if (entry->state.hook == NF_INET_LOCAL_OUT) {
  91                 const struct ipv6hdr *iph = ipv6_hdr(skb);
  92                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  93                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  94                     skb->mark != rt_info->mark)
  95                         return ip6_route_me_harder(entry->state.net, entry->state.sk, skb);
  96         }
  97         return 0;
  98 }
  99
 100 int __nf_ip6_route(struct net *net, struct dst_entry **dst,
 101                    struct flowi *fl, bool strict)
 102 {
 103         static const struct ipv6_pinfo fake_pinfo;
 104         static const struct inet_sock fake_sk = {
 105                 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
 106                 .sk.sk_bound_dev_if = 1,
 107                 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
 108         };
 109         const void *sk = strict ? &fake_sk : NULL;
 110         struct dst_entry *result;
 111         int err;
 112
 113         result = ip6_route_output(net, sk, &fl->u.ip6);
 114         err = result->error;
 115         if (err)
 116                 dst_release(result);
 117         else
 118                 *dst = result;
 119         return err;
 120 }
 121 EXPORT_SYMBOL_GPL(__nf_ip6_route);
 122
 123 int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 124                     struct nf_bridge_frag_data *data,
 125                     int (*output)(struct net *, struct sock *sk,
 126                                   const struct nf_bridge_frag_data *data,
 127                                   struct sk_buff *))
 128 {
 129         int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
 130         ktime_t tstamp = skb->tstamp;
 131         struct ip6_frag_state state;
 132         u8 *prevhdr, nexthdr = 0;
 133         unsigned int mtu, hlen;
 134         int hroom, err = 0;
 135         __be32 frag_id;
 136
 137         err = ip6_find_1stfragopt(skb, &prevhdr);
 138         if (err < 0)
 139                 goto blackhole;
 140         hlen = err;
 141         nexthdr = *prevhdr;
 142
 143         mtu = skb->dev->mtu;
 144         if (frag_max_size > mtu ||
 145             frag_max_size < IPV6_MIN_MTU)
 146                 goto blackhole;
 147
 148         mtu = frag_max_size;
 149         if (mtu < hlen + sizeof(struct frag_hdr) + 8)
 150                 goto blackhole;
 151         mtu -= hlen + sizeof(struct frag_hdr);
 152
 153         frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
 154                                     &ipv6_hdr(skb)->saddr);
 155
 156         if (skb->ip_summed == CHECKSUM_PARTIAL &&
 157             (err = skb_checksum_help(skb)))
 158                 goto blackhole;
 159
 160         hroom = LL_RESERVED_SPACE(skb->dev);
 161         if (skb_has_frag_list(skb)) {
 162                 unsigned int first_len = skb_pagelen(skb);
 163                 struct ip6_fraglist_iter iter;
 164                 struct sk_buff *frag2;
 165
 166                 if (first_len - hlen > mtu ||
 167                     skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
 168                         goto blackhole;
 169
 170                 if (skb_cloned(skb))
 171                         goto slow_path;
 172
 173                 skb_walk_frags(skb, frag2) {
 174                         if (frag2->len > mtu ||
 175                             skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr)))
 176                                 goto blackhole;
 177
 178                         /* Partially cloned skb? */
 179                         if (skb_shared(frag2))
 180                                 goto slow_path;
 181                 }
 182
 183                 err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id,
 184                                         &iter);
 185                 if (err < 0)
 186                         goto blackhole;
 187
 188                 for (;;) {
 189                         /* Prepare header of the next frame,
 190                          * before previous one went down.
 191                          */
 192                         if (iter.frag)
 193                                 ip6_fraglist_prepare(skb, &iter);
 194
 195                         skb->tstamp = tstamp;
 196                         err = output(net, sk, data, skb);
 197                         if (err || !iter.frag)
 198                                 break;
 199
 200                         skb = ip6_fraglist_next(&iter);
 201                 }
 202
 203                 kfree(iter.tmp_hdr);
 204                 if (!err)
 205                         return 0;
 206
 207                 kfree_skb_list(iter.frag);
 208                 return err;
 209         }
 210 slow_path:
 211         /* This is a linearized skbuff, the original geometry is lost for us.
 212          * This may also be a clone skbuff, we could preserve the geometry for
 213          * the copies but probably not worth the effort.
 214          */
 215         ip6_frag_init(skb, hlen, mtu, skb->dev->needed_tailroom,
 216                       LL_RESERVED_SPACE(skb->dev), prevhdr, nexthdr, frag_id,
 217                       &state);
 218
 219         while (state.left > 0) {
 220                 struct sk_buff *skb2;
 221
 222                 skb2 = ip6_frag_next(skb, &state);
 223                 if (IS_ERR(skb2)) {
 224                         err = PTR_ERR(skb2);
 225                         goto blackhole;
 226                 }
 227
 228                 skb2->tstamp = tstamp;
 229                 err = output(net, sk, data, skb2);
 230                 if (err)
 231                         goto blackhole;
 232         }
 233         consume_skb(skb);
 234         return err;
 235
 236 blackhole:
 237         kfree_skb(skb);
 238         return 0;
 239 }
 240 EXPORT_SYMBOL_GPL(br_ip6_fragment);
 241
 242 static const struct nf_ipv6_ops ipv6ops = {
 243 #if IS_MODULE(CONFIG_IPV6)
 244         .chk_addr               = ipv6_chk_addr,
 245         .route_me_harder        = ip6_route_me_harder,
 246         .dev_get_saddr          = ipv6_dev_get_saddr,
 247         .route                  = __nf_ip6_route,
 248 #if IS_ENABLED(CONFIG_SYN_COOKIES)
 249         .cookie_init_sequence   = __cookie_v6_init_sequence,
 250         .cookie_v6_check        = __cookie_v6_check,
 251 #endif
 252 #endif
 253         .route_input            = ip6_route_input,
 254         .fragment               = ip6_fragment,
 255         .reroute                = nf_ip6_reroute,
 256 #if IS_MODULE(CONFIG_IPV6)
 257         .br_fragment            = br_ip6_fragment,
 258 #endif
 259 };
 260
 261 int __init ipv6_netfilter_init(void)
 262 {
 263         RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops);
 264         return 0;
 265 }
 266
 267 /* This can be called from inet6_init() on errors, so it cannot
 268  * be marked __exit. -DaveM
 269  */
 270 void ipv6_netfilter_fini(void)
 271 {
 272         RCU_INIT_POINTER(nf_ipv6_ops, NULL);
 273 }