net/netfilter/nft_bitwise.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   4  *
   5  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/netlink.h>
  12 #include <linux/netfilter.h>
  13 #include <linux/netfilter/nf_tables.h>
  14 #include <net/netfilter/nf_tables_core.h>
  15 #include <net/netfilter/nf_tables.h>
  16
  17 struct nft_bitwise {
  18         enum nft_registers      sreg:8;
  19         enum nft_registers      dreg:8;
  20         u8                      len;
  21         struct nft_data         mask;
  22         struct nft_data         xor;
  23 };
  24
  25 void nft_bitwise_eval(const struct nft_expr *expr,
  26                       struct nft_regs *regs, const struct nft_pktinfo *pkt)
  27 {
  28         const struct nft_bitwise *priv = nft_expr_priv(expr);
  29         const u32 *src = &regs->data[priv->sreg];
  30         u32 *dst = &regs->data[priv->dreg];
  31         unsigned int i;
  32
  33         for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++)
  34                 dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];
  35 }
  36
  37 static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
  38         [NFTA_BITWISE_SREG]     = { .type = NLA_U32 },
  39         [NFTA_BITWISE_DREG]     = { .type = NLA_U32 },
  40         [NFTA_BITWISE_LEN]      = { .type = NLA_U32 },
  41         [NFTA_BITWISE_MASK]     = { .type = NLA_NESTED },
  42         [NFTA_BITWISE_XOR]      = { .type = NLA_NESTED },
  43 };
  44
  45 static int nft_bitwise_init(const struct nft_ctx *ctx,
  46                             const struct nft_expr *expr,
  47                             const struct nlattr * const tb[])
  48 {
  49         struct nft_bitwise *priv = nft_expr_priv(expr);
  50         struct nft_data_desc d1, d2;
  51         u32 len;
  52         int err;
  53
  54         if (tb[NFTA_BITWISE_SREG] == NULL ||
  55             tb[NFTA_BITWISE_DREG] == NULL ||
  56             tb[NFTA_BITWISE_LEN] == NULL ||
  57             tb[NFTA_BITWISE_MASK] == NULL ||
  58             tb[NFTA_BITWISE_XOR] == NULL)
  59                 return -EINVAL;
  60
  61         err = nft_parse_u32_check(tb[NFTA_BITWISE_LEN], U8_MAX, &len);
  62         if (err < 0)
  63                 return err;
  64
  65         priv->len = len;
  66
  67         priv->sreg = nft_parse_register(tb[NFTA_BITWISE_SREG]);
  68         err = nft_validate_register_load(priv->sreg, priv->len);
  69         if (err < 0)
  70                 return err;
  71
  72         priv->dreg = nft_parse_register(tb[NFTA_BITWISE_DREG]);
  73         err = nft_validate_register_store(ctx, priv->dreg, NULL,
  74                                           NFT_DATA_VALUE, priv->len);
  75         if (err < 0)
  76                 return err;
  77
  78         err = nft_data_init(NULL, &priv->mask, sizeof(priv->mask), &d1,
  79                             tb[NFTA_BITWISE_MASK]);
  80         if (err < 0)
  81                 return err;
  82         if (d1.len != priv->len) {
  83                 err = -EINVAL;
  84                 goto err1;
  85         }
  86
  87         err = nft_data_init(NULL, &priv->xor, sizeof(priv->xor), &d2,
  88                             tb[NFTA_BITWISE_XOR]);
  89         if (err < 0)
  90                 goto err1;
  91         if (d2.len != priv->len) {
  92                 err = -EINVAL;
  93                 goto err2;
  94         }
  95
  96         return 0;
  97 err2:
  98         nft_data_release(&priv->xor, d2.type);
  99 err1:
 100         nft_data_release(&priv->mask, d1.type);
 101         return err;
 102 }
 103
 104 static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
 105 {
 106         const struct nft_bitwise *priv = nft_expr_priv(expr);
 107
 108         if (nft_dump_register(skb, NFTA_BITWISE_SREG, priv->sreg))
 109                 goto nla_put_failure;
 110         if (nft_dump_register(skb, NFTA_BITWISE_DREG, priv->dreg))
 111                 goto nla_put_failure;
 112         if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(priv->len)))
 113                 goto nla_put_failure;
 114
 115         if (nft_data_dump(skb, NFTA_BITWISE_MASK, &priv->mask,
 116                           NFT_DATA_VALUE, priv->len) < 0)
 117                 goto nla_put_failure;
 118
 119         if (nft_data_dump(skb, NFTA_BITWISE_XOR, &priv->xor,
 120                           NFT_DATA_VALUE, priv->len) < 0)
 121                 goto nla_put_failure;
 122
 123         return 0;
 124
 125 nla_put_failure:
 126         return -1;
 127 }
 128
 129 static const struct nft_expr_ops nft_bitwise_ops = {
 130         .type           = &nft_bitwise_type,
 131         .size           = NFT_EXPR_SIZE(sizeof(struct nft_bitwise)),
 132         .eval           = nft_bitwise_eval,
 133         .init           = nft_bitwise_init,
 134         .dump           = nft_bitwise_dump,
 135 };
 136
 137 struct nft_expr_type nft_bitwise_type __read_mostly = {
 138         .name           = "bitwise",
 139         .ops            = &nft_bitwise_ops,
 140         .policy         = nft_bitwise_policy,
 141         .maxattr        = NFTA_BITWISE_MAX,
 142         .owner          = THIS_MODULE,
 143 };