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         if (desc.type != NFT_DATA_VALUE) {
  85                 err = -EINVAL;
  86                 nft_data_release(&priv->data, desc.type);
  87                 return err;
  88         }
  89
  90         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
  91         err = nft_validate_register_load(priv->sreg, desc.len);
  92         if (err < 0)
  93                 return err;
  94
  95         priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  96         priv->len = desc.len;
  97         return 0;
  98 }
  99
 100 static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
 101 {
 102         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
 103
 104         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 105                 goto nla_put_failure;
 106         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
 107                 goto nla_put_failure;
 108
 109         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
 110                           NFT_DATA_VALUE, priv->len) < 0)
 111                 goto nla_put_failure;
 112         return 0;
 113
 114 nla_put_failure:
 115         return -1;
 116 }
 117
 118 static int __nft_cmp_offload(struct nft_offload_ctx *ctx,
 119                              struct nft_flow_rule *flow,
 120                              const struct nft_cmp_expr *priv)
 121 {
 122         struct nft_offload_reg *reg = &ctx->regs[priv->sreg];
 123         u8 *mask = (u8 *)&flow->match.mask;
 124         u8 *key = (u8 *)&flow->match.key;
 125
 126         if (priv->op != NFT_CMP_EQ || reg->len != priv->len)
 127                 return -EOPNOTSUPP;
 128
 129         memcpy(key + reg->offset, &priv->data, priv->len);
 130         memcpy(mask + reg->offset, &reg->mask, priv->len);
 131
 132         flow->match.dissector.used_keys |= BIT(reg->key);
 133         flow->match.dissector.offset[reg->key] = reg->base_offset;
 134
 135         if (reg->key == FLOW_DISSECTOR_KEY_META &&
 136             reg->offset == offsetof(struct nft_flow_key, meta.ingress_iftype) &&
 137             nft_reg_load16(priv->data.data) != ARPHRD_ETHER)
 138                 return -EOPNOTSUPP;
 139
 140         nft_offload_update_dependency(ctx, &priv->data, priv->len);
 141
 142         return 0;
 143 }
 144
 145 static int nft_cmp_offload(struct nft_offload_ctx *ctx,
 146                            struct nft_flow_rule *flow,
 147                            const struct nft_expr *expr)
 148 {
 149         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
 150
 151         return __nft_cmp_offload(ctx, flow, priv);
 152 }
 153
 154 static const struct nft_expr_ops nft_cmp_ops = {
 155         .type           = &nft_cmp_type,
 156         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
 157         .eval           = nft_cmp_eval,
 158         .init           = nft_cmp_init,
 159         .dump           = nft_cmp_dump,
 160         .offload        = nft_cmp_offload,
 161 };
 162
 163 static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 164                              const struct nft_expr *expr,
 165                              const struct nlattr * const tb[])
 166 {
 167         struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 168         struct nft_data_desc desc;
 169         struct nft_data data;
 170         u32 mask;
 171         int err;
 172
 173         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 174                             tb[NFTA_CMP_DATA]);
 175         if (err < 0)
 176                 return err;
 177
 178         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 179         err = nft_validate_register_load(priv->sreg, desc.len);
 180         if (err < 0)
 181                 return err;
 182
 183         desc.len *= BITS_PER_BYTE;
 184         mask = nft_cmp_fast_mask(desc.len);
 185
 186         priv->data = data.data[0] & mask;
 187         priv->len  = desc.len;
 188         return 0;
 189 }
 190
 191 static int nft_cmp_fast_offload(struct nft_offload_ctx *ctx,
 192                                 struct nft_flow_rule *flow,
 193                                 const struct nft_expr *expr)
 194 {
 195         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 196         struct nft_cmp_expr cmp = {
 197                 .data   = {
 198                         .data   = {
 199                                 [0] = priv->data,
 200                         },
 201                 },
 202                 .sreg   = priv->sreg,
 203                 .len    = priv->len / BITS_PER_BYTE,
 204                 .op     = NFT_CMP_EQ,
 205         };
 206
 207         return __nft_cmp_offload(ctx, flow, &cmp);
 208 }
 209
 210 static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
 211 {
 212         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 213         struct nft_data data;
 214
 215         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 216                 goto nla_put_failure;
 217         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
 218                 goto nla_put_failure;
 219
 220         data.data[0] = priv->data;
 221         if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
 222                           NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
 223                 goto nla_put_failure;
 224         return 0;
 225
 226 nla_put_failure:
 227         return -1;
 228 }
 229
 230 const struct nft_expr_ops nft_cmp_fast_ops = {
 231         .type           = &nft_cmp_type,
 232         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
 233         .eval           = NULL, /* inlined */
 234         .init           = nft_cmp_fast_init,
 235         .dump           = nft_cmp_fast_dump,
 236         .offload        = nft_cmp_fast_offload,
 237 };
 238
 239 static const struct nft_expr_ops *
 240 nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 241 {
 242         struct nft_data_desc desc;
 243         struct nft_data data;
 244         enum nft_cmp_ops op;
 245         int err;
 246
 247         if (tb[NFTA_CMP_SREG] == NULL ||
 248             tb[NFTA_CMP_OP] == NULL ||
 249             tb[NFTA_CMP_DATA] == NULL)
 250                 return ERR_PTR(-EINVAL);
 251
 252         op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 253         switch (op) {
 254         case NFT_CMP_EQ:
 255         case NFT_CMP_NEQ:
 256         case NFT_CMP_LT:
 257         case NFT_CMP_LTE:
 258         case NFT_CMP_GT:
 259         case NFT_CMP_GTE:
 260                 break;
 261         default:
 262                 return ERR_PTR(-EINVAL);
 263         }
 264
 265         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 266                             tb[NFTA_CMP_DATA]);
 267         if (err < 0)
 268                 return ERR_PTR(err);
 269
 270         if (desc.type != NFT_DATA_VALUE) {
 271                 err = -EINVAL;
 272                 goto err1;
 273         }
 274
 275         if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
 276                 return &nft_cmp_fast_ops;
 277
 278         return &nft_cmp_ops;
 279 err1:
 280         nft_data_release(&data, desc.type);
 281         return ERR_PTR(-EINVAL);
 282 }
 283
 284 struct nft_expr_type nft_cmp_type __read_mostly = {
 285         .name           = "cmp",
 286         .select_ops     = nft_cmp_select_ops,
 287         .policy         = nft_cmp_policy,
 288         .maxattr        = NFTA_CMP_MAX,
 289         .owner          = THIS_MODULE,
 290 };