net/ipv6/netfilter/nft_fib_ipv6.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License version 2 as
   4  * published by the Free Software Foundation.
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/init.h>
   9 #include <linux/module.h>
  10 #include <linux/netlink.h>
  11 #include <linux/netfilter.h>
  12 #include <linux/netfilter/nf_tables.h>
  13 #include <linux/netfilter_ipv6.h>
  14 #include <net/netfilter/nf_tables_core.h>
  15 #include <net/netfilter/nf_tables.h>
  16 #include <net/netfilter/nft_fib.h>
  17
  18 #include <net/ip6_fib.h>
  19 #include <net/ip6_route.h>
  20
  21 static int get_ifindex(const struct net_device *dev)
  22 {
  23         return dev ? dev->ifindex : 0;
  24 }
  25
  26 static int nft_fib6_flowi_init(struct flowi6 *fl6, const struct nft_fib *priv,
  27                                const struct nft_pktinfo *pkt,
  28                                const struct net_device *dev,
  29                                struct ipv6hdr *iph)
  30 {
  31         int lookup_flags = 0;
  32
  33         if (priv->flags & NFTA_FIB_F_DADDR) {
  34                 fl6->daddr = iph->daddr;
  35                 fl6->saddr = iph->saddr;
  36         } else {
  37                 fl6->daddr = iph->saddr;
  38                 fl6->saddr = iph->daddr;
  39         }
  40
  41         if (ipv6_addr_type(&fl6->daddr) & IPV6_ADDR_LINKLOCAL) {
  42                 lookup_flags |= RT6_LOOKUP_F_IFACE;
  43                 fl6->flowi6_oif = get_ifindex(dev ? dev : pkt->skb->dev);
  44         }
  45
  46         if (ipv6_addr_type(&fl6->saddr) & IPV6_ADDR_UNICAST)
  47                 lookup_flags |= RT6_LOOKUP_F_HAS_SADDR;
  48
  49         if (priv->flags & NFTA_FIB_F_MARK)
  50                 fl6->flowi6_mark = pkt->skb->mark;
  51
  52         fl6->flowlabel = (*(__be32 *)iph) & IPV6_FLOWINFO_MASK;
  53
  54         return lookup_flags;
  55 }
  56
  57 static u32 __nft_fib6_eval_type(const struct nft_fib *priv,
  58                                 const struct nft_pktinfo *pkt,
  59                                 struct ipv6hdr *iph)
  60 {
  61         const struct net_device *dev = NULL;
  62         int route_err, addrtype;
  63         struct rt6_info *rt;
  64         struct flowi6 fl6 = {
  65                 .flowi6_iif = LOOPBACK_IFINDEX,
  66                 .flowi6_proto = pkt->tprot,
  67         };
  68         u32 ret = 0;
  69
  70         if (priv->flags & NFTA_FIB_F_IIF)
  71                 dev = nft_in(pkt);
  72         else if (priv->flags & NFTA_FIB_F_OIF)
  73                 dev = nft_out(pkt);
  74
  75         nft_fib6_flowi_init(&fl6, priv, pkt, dev, iph);
  76
  77         if (dev && nf_ipv6_chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
  78                 ret = RTN_LOCAL;
  79
  80         route_err = nf_ip6_route(nft_net(pkt), (struct dst_entry **)&rt,
  81                                  flowi6_to_flowi(&fl6), false);
  82         if (route_err)
  83                 goto err;
  84
  85         if (rt->rt6i_flags & RTF_REJECT) {
  86                 route_err = rt->dst.error;
  87                 dst_release(&rt->dst);
  88                 goto err;
  89         }
  90
  91         if (ipv6_anycast_destination((struct dst_entry *)rt, &fl6.daddr))
  92                 ret = RTN_ANYCAST;
  93         else if (!dev && rt->rt6i_flags & RTF_LOCAL)
  94                 ret = RTN_LOCAL;
  95
  96         dst_release(&rt->dst);
  97
  98         if (ret)
  99                 return ret;
 100
 101         addrtype = ipv6_addr_type(&fl6.daddr);
 102
 103         if (addrtype & IPV6_ADDR_MULTICAST)
 104                 return RTN_MULTICAST;
 105         if (addrtype & IPV6_ADDR_UNICAST)
 106                 return RTN_UNICAST;
 107
 108         return RTN_UNSPEC;
 109  err:
 110         switch (route_err) {
 111         case -EINVAL:
 112                 return RTN_BLACKHOLE;
 113         case -EACCES:
 114                 return RTN_PROHIBIT;
 115         case -EAGAIN:
 116                 return RTN_THROW;
 117         default:
 118                 break;
 119         }
 120
 121         return RTN_UNREACHABLE;
 122 }
 123
 124 void nft_fib6_eval_type(const struct nft_expr *expr, struct nft_regs *regs,
 125                         const struct nft_pktinfo *pkt)
 126 {
 127         const struct nft_fib *priv = nft_expr_priv(expr);
 128         int noff = skb_network_offset(pkt->skb);
 129         u32 *dest = &regs->data[priv->dreg];
 130         struct ipv6hdr *iph, _iph;
 131
 132         iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
 133         if (!iph) {
 134                 regs->verdict.code = NFT_BREAK;
 135                 return;
 136         }
 137
 138         *dest = __nft_fib6_eval_type(priv, pkt, iph);
 139 }
 140 EXPORT_SYMBOL_GPL(nft_fib6_eval_type);
 141
 142 void nft_fib6_eval(const struct nft_expr *expr, struct nft_regs *regs,
 143                    const struct nft_pktinfo *pkt)
 144 {
 145         const struct nft_fib *priv = nft_expr_priv(expr);
 146         int noff = skb_network_offset(pkt->skb);
 147         const struct net_device *oif = NULL;
 148         u32 *dest = &regs->data[priv->dreg];
 149         struct ipv6hdr *iph, _iph;
 150         struct flowi6 fl6 = {
 151                 .flowi6_iif = LOOPBACK_IFINDEX,
 152                 .flowi6_proto = pkt->tprot,
 153         };
 154         struct rt6_info *rt;
 155         int lookup_flags;
 156
 157         if (priv->flags & NFTA_FIB_F_IIF)
 158                 oif = nft_in(pkt);
 159         else if (priv->flags & NFTA_FIB_F_OIF)
 160                 oif = nft_out(pkt);
 161
 162         iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
 163         if (!iph) {
 164                 regs->verdict.code = NFT_BREAK;
 165                 return;
 166         }
 167
 168         lookup_flags = nft_fib6_flowi_init(&fl6, priv, pkt, oif, iph);
 169
 170         if (nft_hook(pkt) == NF_INET_PRE_ROUTING &&
 171             nft_fib_is_loopback(pkt->skb, nft_in(pkt))) {
 172                 nft_fib_store_result(dest, priv, nft_in(pkt));
 173                 return;
 174         }
 175
 176         *dest = 0;
 177         rt = (void *)ip6_route_lookup(nft_net(pkt), &fl6, pkt->skb,
 178                                       lookup_flags);
 179         if (rt->dst.error)
 180                 goto put_rt_err;
 181
 182         /* Should not see RTF_LOCAL here */
 183         if (rt->rt6i_flags & (RTF_REJECT | RTF_ANYCAST | RTF_LOCAL))
 184                 goto put_rt_err;
 185
 186         if (oif && oif != rt->rt6i_idev->dev)
 187                 goto put_rt_err;
 188
 189         nft_fib_store_result(dest, priv, rt->rt6i_idev->dev);
 190  put_rt_err:
 191         ip6_rt_put(rt);
 192 }
 193 EXPORT_SYMBOL_GPL(nft_fib6_eval);
 194
 195 static struct nft_expr_type nft_fib6_type;
 196
 197 static const struct nft_expr_ops nft_fib6_type_ops = {
 198         .type           = &nft_fib6_type,
 199         .size           = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
 200         .eval           = nft_fib6_eval_type,
 201         .init           = nft_fib_init,
 202         .dump           = nft_fib_dump,
 203         .validate       = nft_fib_validate,
 204 };
 205
 206 static const struct nft_expr_ops nft_fib6_ops = {
 207         .type           = &nft_fib6_type,
 208         .size           = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
 209         .eval           = nft_fib6_eval,
 210         .init           = nft_fib_init,
 211         .dump           = nft_fib_dump,
 212         .validate       = nft_fib_validate,
 213 };
 214
 215 static const struct nft_expr_ops *
 216 nft_fib6_select_ops(const struct nft_ctx *ctx,
 217                     const struct nlattr * const tb[])
 218 {
 219         enum nft_fib_result result;
 220
 221         if (!tb[NFTA_FIB_RESULT])
 222                 return ERR_PTR(-EINVAL);
 223
 224         result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
 225
 226         switch (result) {
 227         case NFT_FIB_RESULT_OIF:
 228                 return &nft_fib6_ops;
 229         case NFT_FIB_RESULT_OIFNAME:
 230                 return &nft_fib6_ops;
 231         case NFT_FIB_RESULT_ADDRTYPE:
 232                 return &nft_fib6_type_ops;
 233         default:
 234                 return ERR_PTR(-EOPNOTSUPP);
 235         }
 236 }
 237
 238 static struct nft_expr_type nft_fib6_type __read_mostly = {
 239         .name           = "fib",
 240         .select_ops     = nft_fib6_select_ops,
 241         .policy         = nft_fib_policy,
 242         .maxattr        = NFTA_FIB_MAX,
 243         .family         = NFPROTO_IPV6,
 244         .owner          = THIS_MODULE,
 245 };
 246
 247 static int __init nft_fib6_module_init(void)
 248 {
 249         return nft_register_expr(&nft_fib6_type);
 250 }
 251
 252 static void __exit nft_fib6_module_exit(void)
 253 {
 254         nft_unregister_expr(&nft_fib6_type);
 255 }
 256 module_init(nft_fib6_module_init);
 257 module_exit(nft_fib6_module_exit);
 258
 259 MODULE_LICENSE("GPL");
 260 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
 261 MODULE_ALIAS_NFT_AF_EXPR(10, "fib");