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/if_arp.h>
  14 #include <linux/netfilter/nf_tables.h>
  15 #include <net/netfilter/nf_tables_core.h>
  16 #include <net/netfilter/nf_tables_offload.h>
  17 #include <net/netfilter/nf_tables.h>
  18
  19 struct nft_cmp_expr {
  20         struct nft_data         data;
  21         enum nft_registers      sreg:8;
  22         u8                      len;
  23         enum nft_cmp_ops        op:8;
  24 };
  25
  26 void nft_cmp_eval(const struct nft_expr *expr,
  27                   struct nft_regs *regs,
  28                   const struct nft_pktinfo *pkt)
  29 {
  30         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  31         int d;
  32
  33         d = memcmp(&regs->data[priv->sreg], &priv->data, priv->len);
  34         switch (priv->op) {
  35         case NFT_CMP_EQ:
  36                 if (d != 0)
  37                         goto mismatch;
  38                 break;
  39         case NFT_CMP_NEQ:
  40                 if (d == 0)
  41                         goto mismatch;
  42                 break;
  43         case NFT_CMP_LT:
  44                 if (d == 0)
  45                         goto mismatch;
  46                 /* fall through */
  47         case NFT_CMP_LTE:
  48                 if (d > 0)
  49                         goto mismatch;
  50                 break;
  51         case NFT_CMP_GT:
  52                 if (d == 0)
  53                         goto mismatch;
  54                 /* fall through */
  55         case NFT_CMP_GTE:
  56                 if (d < 0)
  57                         goto mismatch;
  58                 break;
  59         }
  60         return;
  61
  62 mismatch:
  63         regs->verdict.code = NFT_BREAK;
  64 }
  65
  66 static const struct nla_policy nft_cmp_policy[NFTA_CMP_MAX + 1] = {
  67         [NFTA_CMP_SREG]         = { .type = NLA_U32 },
  68         [NFTA_CMP_OP]           = { .type = NLA_U32 },
  69         [NFTA_CMP_DATA]         = { .type = NLA_NESTED },
  70 };
  71
  72 static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  73                         const struct nlattr * const tb[])
  74 {
  75         struct nft_cmp_expr *priv = nft_expr_priv(expr);
  76         struct nft_data_desc desc;
  77         int err;
  78
  79         err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &desc,
  80                             tb[NFTA_CMP_DATA]);
  81         if (err < 0)
  82                 return err;
  83
  84         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
  85         err = nft_validate_register_load(priv->sreg, desc.len);
  86         if (err < 0)
  87                 return err;
  88
  89         priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  90         priv->len = desc.len;
  91         return 0;
  92 }
  93
  94 static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
  95 {
  96         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  97
  98         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
  99                 goto nla_put_failure;
 100         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
 101                 goto nla_put_failure;
 102
 103         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
 104                           NFT_DATA_VALUE, priv->len) < 0)
 105                 goto nla_put_failure;
 106         return 0;
 107
 108 nla_put_failure:
 109         return -1;
 110 }
 111
 112 static int __nft_cmp_offload(struct nft_offload_ctx *ctx,
 113                              struct nft_flow_rule *flow,
 114                              const struct nft_cmp_expr *priv)
 115 {
 116         struct nft_offload_reg *reg = &ctx->regs[priv->sreg];
 117         u8 *mask = (u8 *)&flow->match.mask;
 118         u8 *key = (u8 *)&flow->match.key;
 119
 120         if (priv->op != NFT_CMP_EQ || reg->len != priv->len)
 121                 return -EOPNOTSUPP;
 122
 123         memcpy(key + reg->offset, &priv->data, priv->len);
 124         memcpy(mask + reg->offset, &reg->mask, priv->len);
 125
 126         flow->match.dissector.used_keys |= BIT(reg->key);
 127         flow->match.dissector.offset[reg->key] = reg->base_offset;
 128
 129         if (reg->key == FLOW_DISSECTOR_KEY_META &&
 130             reg->offset == offsetof(struct nft_flow_key, meta.ingress_iftype) &&
 131             nft_reg_load16(priv->data.data) != ARPHRD_ETHER)
 132                 return -EOPNOTSUPP;
 133
 134         nft_offload_update_dependency(ctx, &priv->data, priv->len);
 135
 136         return 0;
 137 }
 138
 139 static int nft_cmp_offload(struct nft_offload_ctx *ctx,
 140                            struct nft_flow_rule *flow,
 141                            const struct nft_expr *expr)
 142 {
 143         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
 144
 145         return __nft_cmp_offload(ctx, flow, priv);
 146 }
 147
 148 static const struct nft_expr_ops nft_cmp_ops = {
 149         .type           = &nft_cmp_type,
 150         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
 151         .eval           = nft_cmp_eval,
 152         .init           = nft_cmp_init,
 153         .dump           = nft_cmp_dump,
 154         .offload        = nft_cmp_offload,
 155 };
 156
 157 static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 158                              const struct nft_expr *expr,
 159                              const struct nlattr * const tb[])
 160 {
 161         struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 162         struct nft_data_desc desc;
 163         struct nft_data data;
 164         u32 mask;
 165         int err;
 166
 167         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 168                             tb[NFTA_CMP_DATA]);
 169         if (err < 0)
 170                 return err;
 171
 172         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 173         err = nft_validate_register_load(priv->sreg, desc.len);
 174         if (err < 0)
 175                 return err;
 176
 177         desc.len *= BITS_PER_BYTE;
 178         mask = nft_cmp_fast_mask(desc.len);
 179
 180         priv->data = data.data[0] & mask;
 181         priv->len  = desc.len;
 182         return 0;
 183 }
 184
 185 static int nft_cmp_fast_offload(struct nft_offload_ctx *ctx,
 186                                 struct nft_flow_rule *flow,
 187                                 const struct nft_expr *expr)
 188 {
 189         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 190         struct nft_cmp_expr cmp = {
 191                 .data   = {
 192                         .data   = {
 193                                 [0] = priv->data,
 194                         },
 195                 },
 196                 .sreg   = priv->sreg,
 197                 .len    = priv->len / BITS_PER_BYTE,
 198                 .op     = NFT_CMP_EQ,
 199         };
 200
 201         return __nft_cmp_offload(ctx, flow, &cmp);
 202 }
 203
 204 static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
 205 {
 206         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 207         struct nft_data data;
 208
 209         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 210                 goto nla_put_failure;
 211         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
 212                 goto nla_put_failure;
 213
 214         data.data[0] = priv->data;
 215         if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
 216                           NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
 217                 goto nla_put_failure;
 218         return 0;
 219
 220 nla_put_failure:
 221         return -1;
 222 }
 223
 224 const struct nft_expr_ops nft_cmp_fast_ops = {
 225         .type           = &nft_cmp_type,
 226         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
 227         .eval           = NULL, /* inlined */
 228         .init           = nft_cmp_fast_init,
 229         .dump           = nft_cmp_fast_dump,
 230         .offload        = nft_cmp_fast_offload,
 231 };
 232
 233 static const struct nft_expr_ops *
 234 nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 235 {
 236         struct nft_data_desc desc;
 237         struct nft_data data;
 238         enum nft_cmp_ops op;
 239         int err;
 240
 241         if (tb[NFTA_CMP_SREG] == NULL ||
 242             tb[NFTA_CMP_OP] == NULL ||
 243             tb[NFTA_CMP_DATA] == NULL)
 244                 return ERR_PTR(-EINVAL);
 245
 246         op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 247         switch (op) {
 248         case NFT_CMP_EQ:
 249         case NFT_CMP_NEQ:
 250         case NFT_CMP_LT:
 251         case NFT_CMP_LTE:
 252         case NFT_CMP_GT:
 253         case NFT_CMP_GTE:
 254                 break;
 255         default:
 256                 return ERR_PTR(-EINVAL);
 257         }
 258
 259         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 260                             tb[NFTA_CMP_DATA]);
 261         if (err < 0)
 262                 return ERR_PTR(err);
 263
 264         if (desc.type != NFT_DATA_VALUE) {
 265                 err = -EINVAL;
 266                 goto err1;
 267         }
 268
 269         if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
 270                 return &nft_cmp_fast_ops;
 271
 272         return &nft_cmp_ops;
 273 err1:
 274         nft_data_release(&data, desc.type);
 275         return ERR_PTR(-EINVAL);
 276 }
 277
 278 struct nft_expr_type nft_cmp_type __read_mostly = {
 279         .name           = "cmp",
 280         .select_ops     = nft_cmp_select_ops,
 281         .policy         = nft_cmp_policy,
 282         .maxattr        = NFTA_CMP_MAX,
 283         .owner          = THIS_MODULE,
 284 };