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 flow_keys flkeys;
  28         unsigned int hh_len;
  29         struct dst_entry *dst;
  30         int strict = (ipv6_addr_type(&iph->daddr) &
  31                       (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL));
  32         struct flowi6 fl6 = {
  33                 .flowi6_oif = sk && sk->sk_bound_dev_if ? sk->sk_bound_dev_if :
  34                         strict ? skb_dst(skb)->dev->ifindex : 0,
  35                 .flowi6_mark = skb->mark,
  36                 .flowi6_uid = sock_net_uid(net, sk),
  37                 .daddr = iph->daddr,
  38                 .saddr = iph->saddr,
  39         };
  40         int err;
  41
  42         fib6_rules_early_flow_dissect(net, skb, &fl6, &flkeys);
  43         dst = ip6_route_output(net, sk, &fl6);
  44         err = dst->error;
  45         if (err) {
  46                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  47                 net_dbg_ratelimited("ip6_route_me_harder: No more route\n");
  48                 dst_release(dst);
  49                 return err;
  50         }
  51
  52         /* Drop old route. */
  53         skb_dst_drop(skb);
  54
  55         skb_dst_set(skb, dst);
  56
  57 #ifdef CONFIG_XFRM
  58         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  59             xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
  60                 skb_dst_set(skb, NULL);
  61                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
  62                 if (IS_ERR(dst))
  63                         return PTR_ERR(dst);
  64                 skb_dst_set(skb, dst);
  65         }
  66 #endif
  67
  68         /* Change in oif may mean change in hh_len. */
  69         hh_len = skb_dst(skb)->dev->hard_header_len;
  70         if (skb_headroom(skb) < hh_len &&
  71             pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
  72                              0, GFP_ATOMIC))
  73                 return -ENOMEM;
  74
  75         return 0;
  76 }
  77 EXPORT_SYMBOL(ip6_route_me_harder);
  78
  79 static 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->state.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(entry->state.net, entry->state.sk, skb);
  90         }
  91         return 0;
  92 }
  93
  94 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 EXPORT_SYMBOL_GPL(__nf_ip6_route);
 116
 117 int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 118                     struct nf_bridge_frag_data *data,
 119                     int (*output)(struct net *, struct sock *sk,
 120                                   const struct nf_bridge_frag_data *data,
 121                                   struct sk_buff *))
 122 {
 123         int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
 124         ktime_t tstamp = skb->tstamp;
 125         struct ip6_frag_state state;
 126         u8 *prevhdr, nexthdr = 0;
 127         unsigned int mtu, hlen;
 128         int hroom, err = 0;
 129         __be32 frag_id;
 130
 131         err = ip6_find_1stfragopt(skb, &prevhdr);
 132         if (err < 0)
 133                 goto blackhole;
 134         hlen = err;
 135         nexthdr = *prevhdr;
 136
 137         mtu = skb->dev->mtu;
 138         if (frag_max_size > mtu ||
 139             frag_max_size < IPV6_MIN_MTU)
 140                 goto blackhole;
 141
 142         mtu = frag_max_size;
 143         if (mtu < hlen + sizeof(struct frag_hdr) + 8)
 144                 goto blackhole;
 145         mtu -= hlen + sizeof(struct frag_hdr);
 146
 147         frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
 148                                     &ipv6_hdr(skb)->saddr);
 149
 150         if (skb->ip_summed == CHECKSUM_PARTIAL &&
 151             (err = skb_checksum_help(skb)))
 152                 goto blackhole;
 153
 154         hroom = LL_RESERVED_SPACE(skb->dev);
 155         if (skb_has_frag_list(skb)) {
 156                 unsigned int first_len = skb_pagelen(skb);
 157                 struct ip6_fraglist_iter iter;
 158                 struct sk_buff *frag2;
 159
 160                 if (first_len - hlen > mtu ||
 161                     skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
 162                         goto blackhole;
 163
 164                 if (skb_cloned(skb))
 165                         goto slow_path;
 166
 167                 skb_walk_frags(skb, frag2) {
 168                         if (frag2->len > mtu ||
 169                             skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr)))
 170                                 goto blackhole;
 171
 172                         /* Partially cloned skb? */
 173                         if (skb_shared(frag2))
 174                                 goto slow_path;
 175                 }
 176
 177                 err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id,
 178                                         &iter);
 179                 if (err < 0)
 180                         goto blackhole;
 181
 182                 for (;;) {
 183                         /* Prepare header of the next frame,
 184                          * before previous one went down.
 185                          */
 186                         if (iter.frag)
 187                                 ip6_fraglist_prepare(skb, &iter);
 188
 189                         skb->tstamp = tstamp;
 190                         err = output(net, sk, data, skb);
 191                         if (err || !iter.frag)
 192                                 break;
 193
 194                         skb = ip6_fraglist_next(&iter);
 195                 }
 196
 197                 kfree(iter.tmp_hdr);
 198                 if (!err)
 199                         return 0;
 200
 201                 kfree_skb_list(iter.frag);
 202                 return err;
 203         }
 204 slow_path:
 205         /* This is a linearized skbuff, the original geometry is lost for us.
 206          * This may also be a clone skbuff, we could preserve the geometry for
 207          * the copies but probably not worth the effort.
 208          */
 209         ip6_frag_init(skb, hlen, mtu, skb->dev->needed_tailroom,
 210                       LL_RESERVED_SPACE(skb->dev), prevhdr, nexthdr, frag_id,
 211                       &state);
 212
 213         while (state.left > 0) {
 214                 struct sk_buff *skb2;
 215
 216                 skb2 = ip6_frag_next(skb, &state);
 217                 if (IS_ERR(skb2)) {
 218                         err = PTR_ERR(skb2);
 219                         goto blackhole;
 220                 }
 221
 222                 skb2->tstamp = tstamp;
 223                 err = output(net, sk, data, skb2);
 224                 if (err)
 225                         goto blackhole;
 226         }
 227         consume_skb(skb);
 228         return err;
 229
 230 blackhole:
 231         kfree_skb(skb);
 232         return 0;
 233 }
 234 EXPORT_SYMBOL_GPL(br_ip6_fragment);
 235
 236 static const struct nf_ipv6_ops ipv6ops = {
 237 #if IS_MODULE(CONFIG_IPV6)
 238         .chk_addr               = ipv6_chk_addr,
 239         .route_me_harder        = ip6_route_me_harder,
 240         .dev_get_saddr          = ipv6_dev_get_saddr,
 241         .route                  = __nf_ip6_route,
 242 #if IS_ENABLED(CONFIG_SYN_COOKIES)
 243         .cookie_init_sequence   = __cookie_v6_init_sequence,
 244         .cookie_v6_check        = __cookie_v6_check,
 245 #endif
 246 #endif
 247         .route_input            = ip6_route_input,
 248         .fragment               = ip6_fragment,
 249         .reroute                = nf_ip6_reroute,
 250 #if IS_MODULE(CONFIG_IPV6)
 251         .br_fragment            = br_ip6_fragment,
 252 #endif
 253 };
 254
 255 int __init ipv6_netfilter_init(void)
 256 {
 257         RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops);
 258         return 0;
 259 }
 260
 261 /* This can be called from inet6_init() on errors, so it cannot
 262  * be marked __exit. -DaveM
 263  */
 264 void ipv6_netfilter_fini(void)
 265 {
 266         RCU_INIT_POINTER(nf_ipv6_ops, NULL);
 267 }