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_regs *regs,
  30                                const struct nft_pktinfo *pkt)
  31 {
  32         const struct nft_byteorder *priv = nft_expr_priv(expr);
  33         u32 *src = &regs->data[priv->sreg];
  34         u32 *dst = &regs->data[priv->dreg];
  35         union { u32 u32; u16 u16; } *s, *d;
  36         unsigned int i;
  37
  38         s = (void *)src;
  39         d = (void *)dst;
  40
  41         switch (priv->size) {
  42         case 4:
  43                 switch (priv->op) {
  44                 case NFT_BYTEORDER_NTOH:
  45                         for (i = 0; i < priv->len / 4; i++)
  46                                 d[i].u32 = ntohl((__force __be32)s[i].u32);
  47                         break;
  48                 case NFT_BYTEORDER_HTON:
  49                         for (i = 0; i < priv->len / 4; i++)
  50                                 d[i].u32 = (__force __u32)htonl(s[i].u32);
  51                         break;
  52                 }
  53                 break;
  54         case 2:
  55                 switch (priv->op) {
  56                 case NFT_BYTEORDER_NTOH:
  57                         for (i = 0; i < priv->len / 2; i++)
  58                                 d[i].u16 = ntohs((__force __be16)s[i].u16);
  59                         break;
  60                 case NFT_BYTEORDER_HTON:
  61                         for (i = 0; i < priv->len / 2; i++)
  62                                 d[i].u16 = (__force __u16)htons(s[i].u16);
  63                         break;
  64                 }
  65                 break;
  66         }
  67 }
  68
  69 static const struct nla_policy nft_byteorder_policy[NFTA_BYTEORDER_MAX + 1] = {
  70         [NFTA_BYTEORDER_SREG]   = { .type = NLA_U32 },
  71         [NFTA_BYTEORDER_DREG]   = { .type = NLA_U32 },
  72         [NFTA_BYTEORDER_OP]     = { .type = NLA_U32 },
  73         [NFTA_BYTEORDER_LEN]    = { .type = NLA_U32 },
  74         [NFTA_BYTEORDER_SIZE]   = { .type = NLA_U32 },
  75 };
  76
  77 static int nft_byteorder_init(const struct nft_ctx *ctx,
  78                               const struct nft_expr *expr,
  79                               const struct nlattr * const tb[])
  80 {
  81         struct nft_byteorder *priv = nft_expr_priv(expr);
  82         int err;
  83
  84         if (tb[NFTA_BYTEORDER_SREG] == NULL ||
  85             tb[NFTA_BYTEORDER_DREG] == NULL ||
  86             tb[NFTA_BYTEORDER_LEN] == NULL ||
  87             tb[NFTA_BYTEORDER_SIZE] == NULL ||
  88             tb[NFTA_BYTEORDER_OP] == NULL)
  89                 return -EINVAL;
  90
  91         priv->op = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_OP]));
  92         switch (priv->op) {
  93         case NFT_BYTEORDER_NTOH:
  94         case NFT_BYTEORDER_HTON:
  95                 break;
  96         default:
  97                 return -EINVAL;
  98         }
  99
 100         priv->size = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_SIZE]));
 101         switch (priv->size) {
 102         case 2:
 103         case 4:
 104                 break;
 105         default:
 106                 return -EINVAL;
 107         }
 108
 109         priv->sreg = nft_parse_register(tb[NFTA_BYTEORDER_SREG]);
 110         priv->len  = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_LEN]));
 111         err = nft_validate_register_load(priv->sreg, priv->len);
 112         if (err < 0)
 113                 return err;
 114
 115         priv->dreg = nft_parse_register(tb[NFTA_BYTEORDER_DREG]);
 116         return nft_validate_register_store(ctx, priv->dreg, NULL,
 117                                            NFT_DATA_VALUE, priv->len);
 118 }
 119
 120 static int nft_byteorder_dump(struct sk_buff *skb, const struct nft_expr *expr)
 121 {
 122         const struct nft_byteorder *priv = nft_expr_priv(expr);
 123
 124         if (nft_dump_register(skb, NFTA_BYTEORDER_SREG, priv->sreg))
 125                 goto nla_put_failure;
 126         if (nft_dump_register(skb, NFTA_BYTEORDER_DREG, priv->dreg))
 127                 goto nla_put_failure;
 128         if (nla_put_be32(skb, NFTA_BYTEORDER_OP, htonl(priv->op)))
 129                 goto nla_put_failure;
 130         if (nla_put_be32(skb, NFTA_BYTEORDER_LEN, htonl(priv->len)))
 131                 goto nla_put_failure;
 132         if (nla_put_be32(skb, NFTA_BYTEORDER_SIZE, htonl(priv->size)))
 133                 goto nla_put_failure;
 134         return 0;
 135
 136 nla_put_failure:
 137         return -1;
 138 }
 139
 140 static struct nft_expr_type nft_byteorder_type;
 141 static const struct nft_expr_ops nft_byteorder_ops = {
 142         .type           = &nft_byteorder_type,
 143         .size           = NFT_EXPR_SIZE(sizeof(struct nft_byteorder)),
 144         .eval           = nft_byteorder_eval,
 145         .init           = nft_byteorder_init,
 146         .dump           = nft_byteorder_dump,
 147 };
 148
 149 static struct nft_expr_type nft_byteorder_type __read_mostly = {
 150         .name           = "byteorder",
 151         .ops            = &nft_byteorder_ops,
 152         .policy         = nft_byteorder_policy,
 153         .maxattr        = NFTA_BYTEORDER_MAX,
 154         .owner          = THIS_MODULE,
 155 };
 156
 157 int __init nft_byteorder_module_init(void)
 158 {
 159         return nft_register_expr(&nft_byteorder_type);
 160 }
 161
 162 void nft_byteorder_module_exit(void)
 163 {
 164         nft_unregister_expr(&nft_byteorder_type);
 165 }