net/netfilter/nft_byteorder.c

   1 /*
   2  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   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  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/netlink.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/netfilter/nf_tables.h>
  17 #include <net/netfilter/nf_tables_core.h>
  18 #include <net/netfilter/nf_tables.h>
  19
  20 struct nft_byteorder {
  21         enum nft_registers      sreg:8;
  22         enum nft_registers      dreg:8;
  23         enum nft_byteorder_ops  op:8;
  24         u8                      len;
  25         u8                      size;
  26 };
  27
  28 static void nft_byteorder_eval(const struct nft_expr *expr,
  29                                struct nft_data data[NFT_REG_MAX + 1],
  30                                const struct nft_pktinfo *pkt)
  31 {
  32         const struct nft_byteorder *priv = nft_expr_priv(expr);
  33         struct nft_data *src = &data[priv->sreg], *dst = &data[priv->dreg];
  34         union { u32 u32; u16 u16; } *s, *d;
  35         unsigned int i;
  36
  37         s = (void *)src->data;
  38         d = (void *)dst->data;
  39
  40         switch (priv->size) {
  41         case 4:
  42                 switch (priv->op) {
  43                 case NFT_BYTEORDER_NTOH:
  44                         for (i = 0; i < priv->len / 4; i++)
  45                                 d[i].u32 = ntohl((__force __be32)s[i].u32);
  46                         break;
  47                 case NFT_BYTEORDER_HTON:
  48                         for (i = 0; i < priv->len / 4; i++)
  49                                 d[i].u32 = (__force __u32)htonl(s[i].u32);
  50                         break;
  51                 }
  52                 break;
  53         case 2:
  54                 switch (priv->op) {
  55                 case NFT_BYTEORDER_NTOH:
  56                         for (i = 0; i < priv->len / 2; i++)
  57                                 d[i].u16 = ntohs((__force __be16)s[i].u16);
  58                         break;
  59                 case NFT_BYTEORDER_HTON:
  60                         for (i = 0; i < priv->len / 2; i++)
  61                                 d[i].u16 = (__force __u16)htons(s[i].u16);
  62                         break;
  63                 }
  64                 break;
  65         }
  66 }
  67
  68 static const struct nla_policy nft_byteorder_policy[NFTA_BYTEORDER_MAX + 1] = {
  69         [NFTA_BYTEORDER_SREG]   = { .type = NLA_U32 },
  70         [NFTA_BYTEORDER_DREG]   = { .type = NLA_U32 },
  71         [NFTA_BYTEORDER_OP]     = { .type = NLA_U32 },
  72         [NFTA_BYTEORDER_LEN]    = { .type = NLA_U32 },
  73         [NFTA_BYTEORDER_SIZE]   = { .type = NLA_U32 },
  74 };
  75
  76 static int nft_byteorder_init(const struct nft_ctx *ctx,
  77                               const struct nft_expr *expr,
  78                               const struct nlattr * const tb[])
  79 {
  80         struct nft_byteorder *priv = nft_expr_priv(expr);
  81         int err;
  82
  83         if (tb[NFTA_BYTEORDER_SREG] == NULL ||
  84             tb[NFTA_BYTEORDER_DREG] == NULL ||
  85             tb[NFTA_BYTEORDER_LEN] == NULL ||
  86             tb[NFTA_BYTEORDER_SIZE] == NULL ||
  87             tb[NFTA_BYTEORDER_OP] == NULL)
  88                 return -EINVAL;
  89
  90         priv->op = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_OP]));
  91         switch (priv->op) {
  92         case NFT_BYTEORDER_NTOH:
  93         case NFT_BYTEORDER_HTON:
  94                 break;
  95         default:
  96                 return -EINVAL;
  97         }
  98
  99         priv->size = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_SIZE]));
 100         switch (priv->size) {
 101         case 2:
 102         case 4:
 103                 break;
 104         default:
 105                 return -EINVAL;
 106         }
 107
 108         priv->sreg = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_SREG]));
 109         priv->len  = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_LEN]));
 110         err = nft_validate_register_load(priv->sreg, priv->len);
 111         if (err < 0)
 112                 return err;
 113
 114         priv->dreg = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_DREG]));
 115         return nft_validate_register_store(ctx, priv->dreg, NULL,
 116                                            NFT_DATA_VALUE, priv->len);
 117 }
 118
 119 static int nft_byteorder_dump(struct sk_buff *skb, const struct nft_expr *expr)
 120 {
 121         const struct nft_byteorder *priv = nft_expr_priv(expr);
 122
 123         if (nla_put_be32(skb, NFTA_BYTEORDER_SREG, htonl(priv->sreg)))
 124                 goto nla_put_failure;
 125         if (nla_put_be32(skb, NFTA_BYTEORDER_DREG, htonl(priv->dreg)))
 126                 goto nla_put_failure;
 127         if (nla_put_be32(skb, NFTA_BYTEORDER_OP, htonl(priv->op)))
 128                 goto nla_put_failure;
 129         if (nla_put_be32(skb, NFTA_BYTEORDER_LEN, htonl(priv->len)))
 130                 goto nla_put_failure;
 131         if (nla_put_be32(skb, NFTA_BYTEORDER_SIZE, htonl(priv->size)))
 132                 goto nla_put_failure;
 133         return 0;
 134
 135 nla_put_failure:
 136         return -1;
 137 }
 138
 139 static struct nft_expr_type nft_byteorder_type;
 140 static const struct nft_expr_ops nft_byteorder_ops = {
 141         .type           = &nft_byteorder_type,
 142         .size           = NFT_EXPR_SIZE(sizeof(struct nft_byteorder)),
 143         .eval           = nft_byteorder_eval,
 144         .init           = nft_byteorder_init,
 145         .dump           = nft_byteorder_dump,
 146 };
 147
 148 static struct nft_expr_type nft_byteorder_type __read_mostly = {
 149         .name           = "byteorder",
 150         .ops            = &nft_byteorder_ops,
 151         .policy         = nft_byteorder_policy,
 152         .maxattr        = NFTA_BYTEORDER_MAX,
 153         .owner          = THIS_MODULE,
 154 };
 155
 156 int __init nft_byteorder_module_init(void)
 157 {
 158         return nft_register_expr(&nft_byteorder_type);
 159 }
 160
 161 void nft_byteorder_module_exit(void)
 162 {
 163         nft_unregister_expr(&nft_byteorder_type);
 164 }