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 bool fib6_is_local(const struct sk_buff *skb)
  22 {
  23         const struct rt6_info *rt = (const void *)skb_dst(skb);
  24
  25         return rt && (rt->rt6i_flags & RTF_LOCAL);
  26 }
  27
  28 static int get_ifindex(const struct net_device *dev)
  29 {
  30         return dev ? dev->ifindex : 0;
  31 }
  32
  33 static int nft_fib6_flowi_init(struct flowi6 *fl6, const struct nft_fib *priv,
  34                                const struct nft_pktinfo *pkt,
  35                                const struct net_device *dev)
  36 {
  37         const struct ipv6hdr *iph = ipv6_hdr(pkt->skb);
  38         int lookup_flags = 0;
  39
  40         if (priv->flags & NFTA_FIB_F_DADDR) {
  41                 fl6->daddr = iph->daddr;
  42                 fl6->saddr = iph->saddr;
  43         } else {
  44                 fl6->daddr = iph->saddr;
  45                 fl6->saddr = iph->daddr;
  46         }
  47
  48         if (ipv6_addr_type(&fl6->daddr) & IPV6_ADDR_LINKLOCAL) {
  49                 lookup_flags |= RT6_LOOKUP_F_IFACE;
  50                 fl6->flowi6_oif = get_ifindex(dev ? dev : pkt->skb->dev);
  51         }
  52
  53         if (ipv6_addr_type(&fl6->saddr) & IPV6_ADDR_UNICAST)
  54                 lookup_flags |= RT6_LOOKUP_F_HAS_SADDR;
  55
  56         if (priv->flags & NFTA_FIB_F_MARK)
  57                 fl6->flowi6_mark = pkt->skb->mark;
  58
  59         fl6->flowlabel = (*(__be32 *)iph) & IPV6_FLOWINFO_MASK;
  60
  61         return lookup_flags;
  62 }
  63
  64 static u32 __nft_fib6_eval_type(const struct nft_fib *priv,
  65                                 const struct nft_pktinfo *pkt)
  66 {
  67         const struct net_device *dev = NULL;
  68         const struct nf_ipv6_ops *v6ops;
  69         const struct nf_afinfo *afinfo;
  70         int route_err, addrtype;
  71         struct rt6_info *rt;
  72         struct flowi6 fl6 = {
  73                 .flowi6_iif = LOOPBACK_IFINDEX,
  74                 .flowi6_proto = pkt->tprot,
  75         };
  76         u32 ret = 0;
  77
  78         afinfo = nf_get_afinfo(NFPROTO_IPV6);
  79         if (!afinfo)
  80                 return RTN_UNREACHABLE;
  81
  82         if (priv->flags & NFTA_FIB_F_IIF)
  83                 dev = nft_in(pkt);
  84         else if (priv->flags & NFTA_FIB_F_OIF)
  85                 dev = nft_out(pkt);
  86
  87         nft_fib6_flowi_init(&fl6, priv, pkt, dev);
  88
  89         v6ops = nf_get_ipv6_ops();
  90         if (dev && v6ops && v6ops->chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
  91                 ret = RTN_LOCAL;
  92
  93         route_err = afinfo->route(nft_net(pkt), (struct dst_entry **)&rt,
  94                                   flowi6_to_flowi(&fl6), false);
  95         if (route_err)
  96                 goto err;
  97
  98         if (rt->rt6i_flags & RTF_REJECT) {
  99                 route_err = rt->dst.error;
 100                 dst_release(&rt->dst);
 101                 goto err;
 102         }
 103
 104         if (ipv6_anycast_destination((struct dst_entry *)rt, &fl6.daddr))
 105                 ret = RTN_ANYCAST;
 106         else if (!dev && rt->rt6i_flags & RTF_LOCAL)
 107                 ret = RTN_LOCAL;
 108
 109         dst_release(&rt->dst);
 110
 111         if (ret)
 112                 return ret;
 113
 114         addrtype = ipv6_addr_type(&fl6.daddr);
 115
 116         if (addrtype & IPV6_ADDR_MULTICAST)
 117                 return RTN_MULTICAST;
 118         if (addrtype & IPV6_ADDR_UNICAST)
 119                 return RTN_UNICAST;
 120
 121         return RTN_UNSPEC;
 122  err:
 123         switch (route_err) {
 124         case -EINVAL:
 125                 return RTN_BLACKHOLE;
 126         case -EACCES:
 127                 return RTN_PROHIBIT;
 128         case -EAGAIN:
 129                 return RTN_THROW;
 130         default:
 131                 break;
 132         }
 133
 134         return RTN_UNREACHABLE;
 135 }
 136
 137 void nft_fib6_eval_type(const struct nft_expr *expr, struct nft_regs *regs,
 138                         const struct nft_pktinfo *pkt)
 139 {
 140         const struct nft_fib *priv = nft_expr_priv(expr);
 141         u32 *dest = &regs->data[priv->dreg];
 142
 143         *dest = __nft_fib6_eval_type(priv, pkt);
 144 }
 145 EXPORT_SYMBOL_GPL(nft_fib6_eval_type);
 146
 147 void nft_fib6_eval(const struct nft_expr *expr, struct nft_regs *regs,
 148                    const struct nft_pktinfo *pkt)
 149 {
 150         const struct nft_fib *priv = nft_expr_priv(expr);
 151         const struct net_device *oif = NULL;
 152         u32 *dest = &regs->data[priv->dreg];
 153         struct flowi6 fl6 = {
 154                 .flowi6_iif = LOOPBACK_IFINDEX,
 155                 .flowi6_proto = pkt->tprot,
 156         };
 157         struct rt6_info *rt;
 158         int lookup_flags;
 159
 160         if (priv->flags & NFTA_FIB_F_IIF)
 161                 oif = nft_in(pkt);
 162         else if (priv->flags & NFTA_FIB_F_OIF)
 163                 oif = nft_out(pkt);
 164
 165         lookup_flags = nft_fib6_flowi_init(&fl6, priv, pkt, oif);
 166
 167         if (nft_hook(pkt) == NF_INET_PRE_ROUTING && fib6_is_local(pkt->skb)) {
 168                 nft_fib_store_result(dest, priv->result, pkt, LOOPBACK_IFINDEX);
 169                 return;
 170         }
 171
 172         *dest = 0;
 173  again:
 174         rt = (void *)ip6_route_lookup(nft_net(pkt), &fl6, lookup_flags);
 175         if (rt->dst.error)
 176                 goto put_rt_err;
 177
 178         /* Should not see RTF_LOCAL here */
 179         if (rt->rt6i_flags & (RTF_REJECT | RTF_ANYCAST | RTF_LOCAL))
 180                 goto put_rt_err;
 181
 182         if (oif && oif != rt->rt6i_idev->dev) {
 183                 /* multipath route? Try again with F_IFACE */
 184                 if ((lookup_flags & RT6_LOOKUP_F_IFACE) == 0) {
 185                         lookup_flags |= RT6_LOOKUP_F_IFACE;
 186                         fl6.flowi6_oif = oif->ifindex;
 187                         ip6_rt_put(rt);
 188                         goto again;
 189                 }
 190         }
 191
 192         switch (priv->result) {
 193         case NFT_FIB_RESULT_OIF:
 194                 *dest = rt->rt6i_idev->dev->ifindex;
 195                 break;
 196         case NFT_FIB_RESULT_OIFNAME:
 197                 strncpy((char *)dest, rt->rt6i_idev->dev->name, IFNAMSIZ);
 198                 break;
 199         default:
 200                 WARN_ON_ONCE(1);
 201                 break;
 202         }
 203
 204  put_rt_err:
 205         ip6_rt_put(rt);
 206 }
 207 EXPORT_SYMBOL_GPL(nft_fib6_eval);
 208
 209 static struct nft_expr_type nft_fib6_type;
 210
 211 static const struct nft_expr_ops nft_fib6_type_ops = {
 212         .type           = &nft_fib6_type,
 213         .size           = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
 214         .eval           = nft_fib6_eval_type,
 215         .init           = nft_fib_init,
 216         .dump           = nft_fib_dump,
 217         .validate       = nft_fib_validate,
 218 };
 219
 220 static const struct nft_expr_ops nft_fib6_ops = {
 221         .type           = &nft_fib6_type,
 222         .size           = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
 223         .eval           = nft_fib6_eval,
 224         .init           = nft_fib_init,
 225         .dump           = nft_fib_dump,
 226         .validate       = nft_fib_validate,
 227 };
 228
 229 static const struct nft_expr_ops *
 230 nft_fib6_select_ops(const struct nft_ctx *ctx,
 231                     const struct nlattr * const tb[])
 232 {
 233         enum nft_fib_result result;
 234
 235         if (!tb[NFTA_FIB_RESULT])
 236                 return ERR_PTR(-EINVAL);
 237
 238         result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
 239
 240         switch (result) {
 241         case NFT_FIB_RESULT_OIF:
 242                 return &nft_fib6_ops;
 243         case NFT_FIB_RESULT_OIFNAME:
 244                 return &nft_fib6_ops;
 245         case NFT_FIB_RESULT_ADDRTYPE:
 246                 return &nft_fib6_type_ops;
 247         default:
 248                 return ERR_PTR(-EOPNOTSUPP);
 249         }
 250 }
 251
 252 static struct nft_expr_type nft_fib6_type __read_mostly = {
 253         .name           = "fib",
 254         .select_ops     = &nft_fib6_select_ops,
 255         .policy         = nft_fib_policy,
 256         .maxattr        = NFTA_FIB_MAX,
 257         .family         = NFPROTO_IPV6,
 258         .owner          = THIS_MODULE,
 259 };
 260
 261 static int __init nft_fib6_module_init(void)
 262 {
 263         return nft_register_expr(&nft_fib6_type);
 264 }
 265
 266 static void __exit nft_fib6_module_exit(void)
 267 {
 268         nft_unregister_expr(&nft_fib6_type);
 269 }
 270 module_init(nft_fib6_module_init);
 271 module_exit(nft_fib6_module_exit);
 272
 273 MODULE_LICENSE("GPL");
 274 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
 275 MODULE_ALIAS_NFT_AF_EXPR(10, "fib");