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 sk_buff *skb)
  24 {
  25         const struct ipv6hdr *iph = ipv6_hdr(skb);
  26         struct sock *sk = sk_to_full_sk(skb->sk);
  27         unsigned int hh_len;
  28         struct dst_entry *dst;
  29         int strict = (ipv6_addr_type(&iph->daddr) &
  30                       (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL));
  31         struct flowi6 fl6 = {
  32                 .flowi6_oif = sk && sk->sk_bound_dev_if ? sk->sk_bound_dev_if :
  33                         strict ? skb_dst(skb)->dev->ifindex : 0,
  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         dst = ip6_route_output(net, sk, &fl6);
  42         err = dst->error;
  43         if (err) {
  44                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  45                 net_dbg_ratelimited("ip6_route_me_harder: No more route\n");
  46                 dst_release(dst);
  47                 return err;
  48         }
  49
  50         /* Drop old route. */
  51         skb_dst_drop(skb);
  52
  53         skb_dst_set(skb, dst);
  54
  55 #ifdef CONFIG_XFRM
  56         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  57             xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
  58                 skb_dst_set(skb, NULL);
  59                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
  60                 if (IS_ERR(dst))
  61                         return PTR_ERR(dst);
  62                 skb_dst_set(skb, dst);
  63         }
  64 #endif
  65
  66         /* Change in oif may mean change in hh_len. */
  67         hh_len = skb_dst(skb)->dev->hard_header_len;
  68         if (skb_headroom(skb) < hh_len &&
  69             pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
  70                              0, GFP_ATOMIC))
  71                 return -ENOMEM;
  72
  73         return 0;
  74 }
  75 EXPORT_SYMBOL(ip6_route_me_harder);
  76
  77 static int nf_ip6_reroute(struct sk_buff *skb,
  78                           const struct nf_queue_entry *entry)
  79 {
  80         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  81
  82         if (entry->state.hook == NF_INET_LOCAL_OUT) {
  83                 const struct ipv6hdr *iph = ipv6_hdr(skb);
  84                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  85                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  86                     skb->mark != rt_info->mark)
  87                         return ip6_route_me_harder(entry->state.net, skb);
  88         }
  89         return 0;
  90 }
  91
  92 int __nf_ip6_route(struct net *net, struct dst_entry **dst,
  93                    struct flowi *fl, bool strict)
  94 {
  95         static const struct ipv6_pinfo fake_pinfo;
  96         static const struct inet_sock fake_sk = {
  97                 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
  98                 .sk.sk_bound_dev_if = 1,
  99                 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
 100         };
 101         const void *sk = strict ? &fake_sk : NULL;
 102         struct dst_entry *result;
 103         int err;
 104
 105         result = ip6_route_output(net, sk, &fl->u.ip6);
 106         err = result->error;
 107         if (err)
 108                 dst_release(result);
 109         else
 110                 *dst = result;
 111         return err;
 112 }
 113 EXPORT_SYMBOL_GPL(__nf_ip6_route);
 114
 115 int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 116                     struct nf_bridge_frag_data *data,
 117                     int (*output)(struct net *, struct sock *sk,
 118                                   const struct nf_bridge_frag_data *data,
 119                                   struct sk_buff *))
 120 {
 121         int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
 122         ktime_t tstamp = skb->tstamp;
 123         struct ip6_frag_state state;
 124         u8 *prevhdr, nexthdr = 0;
 125         unsigned int mtu, hlen;
 126         int hroom, err = 0;
 127         __be32 frag_id;
 128
 129         err = ip6_find_1stfragopt(skb, &prevhdr);
 130         if (err < 0)
 131                 goto blackhole;
 132         hlen = err;
 133         nexthdr = *prevhdr;
 134
 135         mtu = skb->dev->mtu;
 136         if (frag_max_size > mtu ||
 137             frag_max_size < IPV6_MIN_MTU)
 138                 goto blackhole;
 139
 140         mtu = frag_max_size;
 141         if (mtu < hlen + sizeof(struct frag_hdr) + 8)
 142                 goto blackhole;
 143         mtu -= hlen + sizeof(struct frag_hdr);
 144
 145         frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
 146                                     &ipv6_hdr(skb)->saddr);
 147
 148         if (skb->ip_summed == CHECKSUM_PARTIAL &&
 149             (err = skb_checksum_help(skb)))
 150                 goto blackhole;
 151
 152         hroom = LL_RESERVED_SPACE(skb->dev);
 153         if (skb_has_frag_list(skb)) {
 154                 unsigned int first_len = skb_pagelen(skb);
 155                 struct ip6_fraglist_iter iter;
 156                 struct sk_buff *frag2;
 157
 158                 if (first_len - hlen > mtu ||
 159                     skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
 160                         goto blackhole;
 161
 162                 if (skb_cloned(skb))
 163                         goto slow_path;
 164
 165                 skb_walk_frags(skb, frag2) {
 166                         if (frag2->len > mtu ||
 167                             skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr)))
 168                                 goto blackhole;
 169
 170                         /* Partially cloned skb? */
 171                         if (skb_shared(frag2))
 172                                 goto slow_path;
 173                 }
 174
 175                 err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id,
 176                                         &iter);
 177                 if (err < 0)
 178                         goto blackhole;
 179
 180                 for (;;) {
 181                         /* Prepare header of the next frame,
 182                          * before previous one went down.
 183                          */
 184                         if (iter.frag)
 185                                 ip6_fraglist_prepare(skb, &iter);
 186
 187                         skb->tstamp = tstamp;
 188                         err = output(net, sk, data, skb);
 189                         if (err || !iter.frag)
 190                                 break;
 191
 192                         skb = ip6_fraglist_next(&iter);
 193                 }
 194
 195                 kfree(iter.tmp_hdr);
 196                 if (!err)
 197                         return 0;
 198
 199                 kfree_skb_list(iter.frag);
 200                 return err;
 201         }
 202 slow_path:
 203         /* This is a linearized skbuff, the original geometry is lost for us.
 204          * This may also be a clone skbuff, we could preserve the geometry for
 205          * the copies but probably not worth the effort.
 206          */
 207         ip6_frag_init(skb, hlen, mtu, skb->dev->needed_tailroom,
 208                       LL_RESERVED_SPACE(skb->dev), prevhdr, nexthdr, frag_id,
 209                       &state);
 210
 211         while (state.left > 0) {
 212                 struct sk_buff *skb2;
 213
 214                 skb2 = ip6_frag_next(skb, &state);
 215                 if (IS_ERR(skb2)) {
 216                         err = PTR_ERR(skb2);
 217                         goto blackhole;
 218                 }
 219
 220                 skb2->tstamp = tstamp;
 221                 err = output(net, sk, data, skb2);
 222                 if (err)
 223                         goto blackhole;
 224         }
 225         consume_skb(skb);
 226         return err;
 227
 228 blackhole:
 229         kfree_skb(skb);
 230         return 0;
 231 }
 232 EXPORT_SYMBOL_GPL(br_ip6_fragment);
 233
 234 static const struct nf_ipv6_ops ipv6ops = {
 235 #if IS_MODULE(CONFIG_IPV6)
 236         .chk_addr               = ipv6_chk_addr,
 237         .route_me_harder        = ip6_route_me_harder,
 238         .dev_get_saddr          = ipv6_dev_get_saddr,
 239         .route                  = __nf_ip6_route,
 240 #if IS_ENABLED(CONFIG_SYN_COOKIES)
 241         .cookie_init_sequence   = __cookie_v6_init_sequence,
 242         .cookie_v6_check        = __cookie_v6_check,
 243 #endif
 244 #endif
 245         .route_input            = ip6_route_input,
 246         .fragment               = ip6_fragment,
 247         .reroute                = nf_ip6_reroute,
 248 #if IS_MODULE(CONFIG_IPV6) && IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
 249         .br_defrag              = nf_ct_frag6_gather,
 250 #endif
 251 #if IS_MODULE(CONFIG_IPV6)
 252         .br_fragment            = br_ip6_fragment,
 253 #endif
 254 };
 255
 256 int __init ipv6_netfilter_init(void)
 257 {
 258         RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops);
 259         return 0;
 260 }
 261
 262 /* This can be called from inet6_init() on errors, so it cannot
 263  * be marked __exit. -DaveM
 264  */
 265 void ipv6_netfilter_fini(void)
 266 {
 267         RCU_INIT_POINTER(nf_ipv6_ops, NULL);
 268 }