net/netfilter/nft_cmp.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_cmp_expr {
  18         struct nft_data         data;
  19         enum nft_registers      sreg:8;
  20         u8                      len;
  21         enum nft_cmp_ops        op:8;
  22 };
  23
  24 void nft_cmp_eval(const struct nft_expr *expr,
  25                   struct nft_regs *regs,
  26                   const struct nft_pktinfo *pkt)
  27 {
  28         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  29         int d;
  30
  31         d = memcmp(&regs->data[priv->sreg], &priv->data, priv->len);
  32         switch (priv->op) {
  33         case NFT_CMP_EQ:
  34                 if (d != 0)
  35                         goto mismatch;
  36                 break;
  37         case NFT_CMP_NEQ:
  38                 if (d == 0)
  39                         goto mismatch;
  40                 break;
  41         case NFT_CMP_LT:
  42                 if (d == 0)
  43                         goto mismatch;
  44                 /* fall through */
  45         case NFT_CMP_LTE:
  46                 if (d > 0)
  47                         goto mismatch;
  48                 break;
  49         case NFT_CMP_GT:
  50                 if (d == 0)
  51                         goto mismatch;
  52                 /* fall through */
  53         case NFT_CMP_GTE:
  54                 if (d < 0)
  55                         goto mismatch;
  56                 break;
  57         }
  58         return;
  59
  60 mismatch:
  61         regs->verdict.code = NFT_BREAK;
  62 }
  63
  64 static const struct nla_policy nft_cmp_policy[NFTA_CMP_MAX + 1] = {
  65         [NFTA_CMP_SREG]         = { .type = NLA_U32 },
  66         [NFTA_CMP_OP]           = { .type = NLA_U32 },
  67         [NFTA_CMP_DATA]         = { .type = NLA_NESTED },
  68 };
  69
  70 static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  71                         const struct nlattr * const tb[])
  72 {
  73         struct nft_cmp_expr *priv = nft_expr_priv(expr);
  74         struct nft_data_desc desc;
  75         int err;
  76
  77         err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &desc,
  78                             tb[NFTA_CMP_DATA]);
  79         if (err < 0)
  80                 return err;
  81
  82         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
  83         err = nft_validate_register_load(priv->sreg, desc.len);
  84         if (err < 0)
  85                 return err;
  86
  87         priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  88         priv->len = desc.len;
  89         return 0;
  90 }
  91
  92 static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
  93 {
  94         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  95
  96         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
  97                 goto nla_put_failure;
  98         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
  99                 goto nla_put_failure;
 100
 101         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
 102                           NFT_DATA_VALUE, priv->len) < 0)
 103                 goto nla_put_failure;
 104         return 0;
 105
 106 nla_put_failure:
 107         return -1;
 108 }
 109
 110 static const struct nft_expr_ops nft_cmp_ops = {
 111         .type           = &nft_cmp_type,
 112         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
 113         .eval           = nft_cmp_eval,
 114         .init           = nft_cmp_init,
 115         .dump           = nft_cmp_dump,
 116 };
 117
 118 static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 119                              const struct nft_expr *expr,
 120                              const struct nlattr * const tb[])
 121 {
 122         struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 123         struct nft_data_desc desc;
 124         struct nft_data data;
 125         u32 mask;
 126         int err;
 127
 128         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 129                             tb[NFTA_CMP_DATA]);
 130         if (err < 0)
 131                 return err;
 132
 133         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 134         err = nft_validate_register_load(priv->sreg, desc.len);
 135         if (err < 0)
 136                 return err;
 137
 138         desc.len *= BITS_PER_BYTE;
 139         mask = nft_cmp_fast_mask(desc.len);
 140
 141         priv->data = data.data[0] & mask;
 142         priv->len  = desc.len;
 143         return 0;
 144 }
 145
 146 static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
 147 {
 148         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 149         struct nft_data data;
 150
 151         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 152                 goto nla_put_failure;
 153         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
 154                 goto nla_put_failure;
 155
 156         data.data[0] = priv->data;
 157         if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
 158                           NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
 159                 goto nla_put_failure;
 160         return 0;
 161
 162 nla_put_failure:
 163         return -1;
 164 }
 165
 166 const struct nft_expr_ops nft_cmp_fast_ops = {
 167         .type           = &nft_cmp_type,
 168         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
 169         .eval           = NULL, /* inlined */
 170         .init           = nft_cmp_fast_init,
 171         .dump           = nft_cmp_fast_dump,
 172 };
 173
 174 static const struct nft_expr_ops *
 175 nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 176 {
 177         struct nft_data_desc desc;
 178         struct nft_data data;
 179         enum nft_cmp_ops op;
 180         int err;
 181
 182         if (tb[NFTA_CMP_SREG] == NULL ||
 183             tb[NFTA_CMP_OP] == NULL ||
 184             tb[NFTA_CMP_DATA] == NULL)
 185                 return ERR_PTR(-EINVAL);
 186
 187         op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 188         switch (op) {
 189         case NFT_CMP_EQ:
 190         case NFT_CMP_NEQ:
 191         case NFT_CMP_LT:
 192         case NFT_CMP_LTE:
 193         case NFT_CMP_GT:
 194         case NFT_CMP_GTE:
 195                 break;
 196         default:
 197                 return ERR_PTR(-EINVAL);
 198         }
 199
 200         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 201                             tb[NFTA_CMP_DATA]);
 202         if (err < 0)
 203                 return ERR_PTR(err);
 204
 205         if (desc.type != NFT_DATA_VALUE) {
 206                 err = -EINVAL;
 207                 goto err1;
 208         }
 209
 210         if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
 211                 return &nft_cmp_fast_ops;
 212
 213         return &nft_cmp_ops;
 214 err1:
 215         nft_data_release(&data, desc.type);
 216         return ERR_PTR(-EINVAL);
 217 }
 218
 219 struct nft_expr_type nft_cmp_type __read_mostly = {
 220         .name           = "cmp",
 221         .select_ops     = nft_cmp_select_ops,
 222         .policy         = nft_cmp_policy,
 223         .maxattr        = NFTA_CMP_MAX,
 224         .owner          = THIS_MODULE,
 225 };