net/netfilter/nft_rt.c

   1 /*
   2  * Copyright (c) 2016 Anders K. Pedersen <akp@cohaesio.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/netlink.h>
  13 #include <linux/netfilter.h>
  14 #include <linux/netfilter/nf_tables.h>
  15 #include <net/dst.h>
  16 #include <net/ip6_route.h>
  17 #include <net/route.h>
  18 #include <net/netfilter/nf_tables.h>
  19 #include <net/netfilter/nf_tables_core.h>
  20
  21 struct nft_rt {
  22         enum nft_rt_keys        key:8;
  23         enum nft_registers      dreg:8;
  24 };
  25
  26 static void nft_rt_get_eval(const struct nft_expr *expr,
  27                             struct nft_regs *regs,
  28                             const struct nft_pktinfo *pkt)
  29 {
  30         const struct nft_rt *priv = nft_expr_priv(expr);
  31         const struct sk_buff *skb = pkt->skb;
  32         u32 *dest = &regs->data[priv->dreg];
  33         const struct dst_entry *dst;
  34
  35         dst = skb_dst(skb);
  36         if (!dst)
  37                 goto err;
  38
  39         switch (priv->key) {
  40 #ifdef CONFIG_IP_ROUTE_CLASSID
  41         case NFT_RT_CLASSID:
  42                 *dest = dst->tclassid;
  43                 break;
  44 #endif
  45         case NFT_RT_NEXTHOP4:
  46                 if (nft_pf(pkt) != NFPROTO_IPV4)
  47                         goto err;
  48
  49                 *dest = rt_nexthop((const struct rtable *)dst,
  50                                    ip_hdr(skb)->daddr);
  51                 break;
  52         case NFT_RT_NEXTHOP6:
  53                 if (nft_pf(pkt) != NFPROTO_IPV6)
  54                         goto err;
  55
  56                 memcpy(dest, rt6_nexthop((struct rt6_info *)dst,
  57                                          &ipv6_hdr(skb)->daddr),
  58                        sizeof(struct in6_addr));
  59                 break;
  60         default:
  61                 WARN_ON(1);
  62                 goto err;
  63         }
  64         return;
  65
  66 err:
  67         regs->verdict.code = NFT_BREAK;
  68 }
  69
  70 const struct nla_policy nft_rt_policy[NFTA_RT_MAX + 1] = {
  71         [NFTA_RT_DREG]          = { .type = NLA_U32 },
  72         [NFTA_RT_KEY]           = { .type = NLA_U32 },
  73 };
  74
  75 static int nft_rt_get_init(const struct nft_ctx *ctx,
  76                            const struct nft_expr *expr,
  77                            const struct nlattr * const tb[])
  78 {
  79         struct nft_rt *priv = nft_expr_priv(expr);
  80         unsigned int len;
  81
  82         if (tb[NFTA_RT_KEY] == NULL ||
  83             tb[NFTA_RT_DREG] == NULL)
  84                 return -EINVAL;
  85
  86         priv->key = ntohl(nla_get_be32(tb[NFTA_RT_KEY]));
  87         switch (priv->key) {
  88 #ifdef CONFIG_IP_ROUTE_CLASSID
  89         case NFT_RT_CLASSID:
  90 #endif
  91         case NFT_RT_NEXTHOP4:
  92                 len = sizeof(u32);
  93                 break;
  94         case NFT_RT_NEXTHOP6:
  95                 len = sizeof(struct in6_addr);
  96                 break;
  97         default:
  98                 return -EOPNOTSUPP;
  99         }
 100
 101         priv->dreg = nft_parse_register(tb[NFTA_RT_DREG]);
 102         return nft_validate_register_store(ctx, priv->dreg, NULL,
 103                                            NFT_DATA_VALUE, len);
 104 }
 105
 106 static int nft_rt_get_dump(struct sk_buff *skb,
 107                            const struct nft_expr *expr)
 108 {
 109         const struct nft_rt *priv = nft_expr_priv(expr);
 110
 111         if (nla_put_be32(skb, NFTA_RT_KEY, htonl(priv->key)))
 112                 goto nla_put_failure;
 113         if (nft_dump_register(skb, NFTA_RT_DREG, priv->dreg))
 114                 goto nla_put_failure;
 115         return 0;
 116
 117 nla_put_failure:
 118         return -1;
 119 }
 120
 121 static struct nft_expr_type nft_rt_type;
 122 static const struct nft_expr_ops nft_rt_get_ops = {
 123         .type           = &nft_rt_type,
 124         .size           = NFT_EXPR_SIZE(sizeof(struct nft_rt)),
 125         .eval           = nft_rt_get_eval,
 126         .init           = nft_rt_get_init,
 127         .dump           = nft_rt_get_dump,
 128 };
 129
 130 static struct nft_expr_type nft_rt_type __read_mostly = {
 131         .name           = "rt",
 132         .ops            = &nft_rt_get_ops,
 133         .policy         = nft_rt_policy,
 134         .maxattr        = NFTA_RT_MAX,
 135         .owner          = THIS_MODULE,
 136 };
 137
 138 static int __init nft_rt_module_init(void)
 139 {
 140         return nft_register_expr(&nft_rt_type);
 141 }
 142
 143 static void __exit nft_rt_module_exit(void)
 144 {
 145         nft_unregister_expr(&nft_rt_type);
 146 }
 147
 148 module_init(nft_rt_module_init);
 149 module_exit(nft_rt_module_exit);
 150
 151 MODULE_LICENSE("GPL");
 152 MODULE_AUTHOR("Anders K. Pedersen <akp@cohaesio.com>");
 153 MODULE_ALIAS_NFT_EXPR("rt");