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