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         u8                      sreg;
  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                 fallthrough;
  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                 fallthrough;
  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                 .type   = NFT_DATA_VALUE,
  78                 .size   = sizeof(priv->data),
  79         };
  80         int err;
  81
  82         err = nft_data_init(NULL, &priv->data, &desc, tb[NFTA_CMP_DATA]);
  83         if (err < 0)
  84                 return err;
  85
  86         err = nft_parse_register_load(ctx, tb[NFTA_CMP_SREG], &priv->sreg, desc.len);
  87         if (err < 0)
  88                 return err;
  89
  90         priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  91         priv->len = desc.len;
  92         return 0;
  93 }
  94
  95 static int nft_cmp_dump(struct sk_buff *skb,
  96                         const struct nft_expr *expr, bool reset)
  97 {
  98         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  99
 100         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 101                 goto nla_put_failure;
 102         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
 103                 goto nla_put_failure;
 104
 105         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
 106                           NFT_DATA_VALUE, priv->len) < 0)
 107                 goto nla_put_failure;
 108         return 0;
 109
 110 nla_put_failure:
 111         return -1;
 112 }
 113
 114 union nft_cmp_offload_data {
 115         u16     val16;
 116         u32     val32;
 117         u64     val64;
 118 };
 119
 120 static void nft_payload_n2h(union nft_cmp_offload_data *data,
 121                             const u8 *val, u32 len)
 122 {
 123         switch (len) {
 124         case 2:
 125                 data->val16 = ntohs(*((__be16 *)val));
 126                 break;
 127         case 4:
 128                 data->val32 = ntohl(*((__be32 *)val));
 129                 break;
 130         case 8:
 131                 data->val64 = be64_to_cpu(*((__be64 *)val));
 132                 break;
 133         default:
 134                 WARN_ON_ONCE(1);
 135                 break;
 136         }
 137 }
 138
 139 static int __nft_cmp_offload(struct nft_offload_ctx *ctx,
 140                              struct nft_flow_rule *flow,
 141                              const struct nft_cmp_expr *priv)
 142 {
 143         struct nft_offload_reg *reg = &ctx->regs[priv->sreg];
 144         union nft_cmp_offload_data _data, _datamask;
 145         u8 *mask = (u8 *)&flow->match.mask;
 146         u8 *key = (u8 *)&flow->match.key;
 147         u8 *data, *datamask;
 148
 149         if (priv->op != NFT_CMP_EQ || priv->len > reg->len)
 150                 return -EOPNOTSUPP;
 151
 152         if (reg->flags & NFT_OFFLOAD_F_NETWORK2HOST) {
 153                 nft_payload_n2h(&_data, (u8 *)&priv->data, reg->len);
 154                 nft_payload_n2h(&_datamask, (u8 *)&reg->mask, reg->len);
 155                 data = (u8 *)&_data;
 156                 datamask = (u8 *)&_datamask;
 157         } else {
 158                 data = (u8 *)&priv->data;
 159                 datamask = (u8 *)&reg->mask;
 160         }
 161
 162         memcpy(key + reg->offset, data, reg->len);
 163         memcpy(mask + reg->offset, datamask, reg->len);
 164
 165         flow->match.dissector.used_keys |= BIT_ULL(reg->key);
 166         flow->match.dissector.offset[reg->key] = reg->base_offset;
 167
 168         if (reg->key == FLOW_DISSECTOR_KEY_META &&
 169             reg->offset == offsetof(struct nft_flow_key, meta.ingress_iftype) &&
 170             nft_reg_load16(priv->data.data) != ARPHRD_ETHER)
 171                 return -EOPNOTSUPP;
 172
 173         nft_offload_update_dependency(ctx, &priv->data, reg->len);
 174
 175         return 0;
 176 }
 177
 178 static int nft_cmp_offload(struct nft_offload_ctx *ctx,
 179                            struct nft_flow_rule *flow,
 180                            const struct nft_expr *expr)
 181 {
 182         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
 183
 184         return __nft_cmp_offload(ctx, flow, priv);
 185 }
 186
 187 static const struct nft_expr_ops nft_cmp_ops = {
 188         .type           = &nft_cmp_type,
 189         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
 190         .eval           = nft_cmp_eval,
 191         .init           = nft_cmp_init,
 192         .dump           = nft_cmp_dump,
 193         .reduce         = NFT_REDUCE_READONLY,
 194         .offload        = nft_cmp_offload,
 195 };
 196
 197 /* Calculate the mask for the nft_cmp_fast expression. On big endian the
 198  * mask needs to include the *upper* bytes when interpreting that data as
 199  * something smaller than the full u32, therefore a cpu_to_le32 is done.
 200  */
 201 static u32 nft_cmp_fast_mask(unsigned int len)
 202 {
 203         __le32 mask = cpu_to_le32(~0U >> (sizeof_field(struct nft_cmp_fast_expr,
 204                                           data) * BITS_PER_BYTE - len));
 205
 206         return (__force u32)mask;
 207 }
 208
 209 static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 210                              const struct nft_expr *expr,
 211                              const struct nlattr * const tb[])
 212 {
 213         struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 214         struct nft_data data;
 215         struct nft_data_desc desc = {
 216                 .type   = NFT_DATA_VALUE,
 217                 .size   = sizeof(data),
 218         };
 219         int err;
 220
 221         err = nft_data_init(NULL, &data, &desc, tb[NFTA_CMP_DATA]);
 222         if (err < 0)
 223                 return err;
 224
 225         err = nft_parse_register_load(ctx, tb[NFTA_CMP_SREG], &priv->sreg, desc.len);
 226         if (err < 0)
 227                 return err;
 228
 229         desc.len *= BITS_PER_BYTE;
 230
 231         priv->mask = nft_cmp_fast_mask(desc.len);
 232         priv->data = data.data[0] & priv->mask;
 233         priv->len  = desc.len;
 234         priv->inv  = ntohl(nla_get_be32(tb[NFTA_CMP_OP])) != NFT_CMP_EQ;
 235         return 0;
 236 }
 237
 238 static int nft_cmp_fast_offload(struct nft_offload_ctx *ctx,
 239                                 struct nft_flow_rule *flow,
 240                                 const struct nft_expr *expr)
 241 {
 242         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 243         struct nft_cmp_expr cmp = {
 244                 .data   = {
 245                         .data   = {
 246                                 [0] = priv->data,
 247                         },
 248                 },
 249                 .sreg   = priv->sreg,
 250                 .len    = priv->len / BITS_PER_BYTE,
 251                 .op     = priv->inv ? NFT_CMP_NEQ : NFT_CMP_EQ,
 252         };
 253
 254         return __nft_cmp_offload(ctx, flow, &cmp);
 255 }
 256
 257 static int nft_cmp_fast_dump(struct sk_buff *skb,
 258                              const struct nft_expr *expr, bool reset)
 259 {
 260         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 261         enum nft_cmp_ops op = priv->inv ? NFT_CMP_NEQ : NFT_CMP_EQ;
 262         struct nft_data data;
 263
 264         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 265                 goto nla_put_failure;
 266         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(op)))
 267                 goto nla_put_failure;
 268
 269         data.data[0] = priv->data;
 270         if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
 271                           NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
 272                 goto nla_put_failure;
 273         return 0;
 274
 275 nla_put_failure:
 276         return -1;
 277 }
 278
 279 const struct nft_expr_ops nft_cmp_fast_ops = {
 280         .type           = &nft_cmp_type,
 281         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
 282         .eval           = NULL, /* inlined */
 283         .init           = nft_cmp_fast_init,
 284         .dump           = nft_cmp_fast_dump,
 285         .reduce         = NFT_REDUCE_READONLY,
 286         .offload        = nft_cmp_fast_offload,
 287 };
 288
 289 static u32 nft_cmp_mask(u32 bitlen)
 290 {
 291         return (__force u32)cpu_to_le32(~0U >> (sizeof(u32) * BITS_PER_BYTE - bitlen));
 292 }
 293
 294 static void nft_cmp16_fast_mask(struct nft_data *data, unsigned int bitlen)
 295 {
 296         int len = bitlen / BITS_PER_BYTE;
 297         int i, words = len / sizeof(u32);
 298
 299         for (i = 0; i < words; i++) {
 300                 data->data[i] = 0xffffffff;
 301                 bitlen -= sizeof(u32) * BITS_PER_BYTE;
 302         }
 303
 304         if (len % sizeof(u32))
 305                 data->data[i++] = nft_cmp_mask(bitlen);
 306
 307         for (; i < 4; i++)
 308                 data->data[i] = 0;
 309 }
 310
 311 static int nft_cmp16_fast_init(const struct nft_ctx *ctx,
 312                                const struct nft_expr *expr,
 313                                const struct nlattr * const tb[])
 314 {
 315         struct nft_cmp16_fast_expr *priv = nft_expr_priv(expr);
 316         struct nft_data_desc desc = {
 317                 .type   = NFT_DATA_VALUE,
 318                 .size   = sizeof(priv->data),
 319         };
 320         int err;
 321
 322         err = nft_data_init(NULL, &priv->data, &desc, tb[NFTA_CMP_DATA]);
 323         if (err < 0)
 324                 return err;
 325
 326         err = nft_parse_register_load(ctx, tb[NFTA_CMP_SREG], &priv->sreg, desc.len);
 327         if (err < 0)
 328                 return err;
 329
 330         nft_cmp16_fast_mask(&priv->mask, desc.len * BITS_PER_BYTE);
 331         priv->inv = ntohl(nla_get_be32(tb[NFTA_CMP_OP])) != NFT_CMP_EQ;
 332         priv->len = desc.len;
 333
 334         return 0;
 335 }
 336
 337 static int nft_cmp16_fast_offload(struct nft_offload_ctx *ctx,
 338                                   struct nft_flow_rule *flow,
 339                                   const struct nft_expr *expr)
 340 {
 341         const struct nft_cmp16_fast_expr *priv = nft_expr_priv(expr);
 342         struct nft_cmp_expr cmp = {
 343                 .data   = priv->data,
 344                 .sreg   = priv->sreg,
 345                 .len    = priv->len,
 346                 .op     = priv->inv ? NFT_CMP_NEQ : NFT_CMP_EQ,
 347         };
 348
 349         return __nft_cmp_offload(ctx, flow, &cmp);
 350 }
 351
 352 static int nft_cmp16_fast_dump(struct sk_buff *skb,
 353                                const struct nft_expr *expr, bool reset)
 354 {
 355         const struct nft_cmp16_fast_expr *priv = nft_expr_priv(expr);
 356         enum nft_cmp_ops op = priv->inv ? NFT_CMP_NEQ : NFT_CMP_EQ;
 357
 358         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 359                 goto nla_put_failure;
 360         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(op)))
 361                 goto nla_put_failure;
 362
 363         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
 364                           NFT_DATA_VALUE, priv->len) < 0)
 365                 goto nla_put_failure;
 366         return 0;
 367
 368 nla_put_failure:
 369         return -1;
 370 }
 371
 372
 373 const struct nft_expr_ops nft_cmp16_fast_ops = {
 374         .type           = &nft_cmp_type,
 375         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp16_fast_expr)),
 376         .eval           = NULL, /* inlined */
 377         .init           = nft_cmp16_fast_init,
 378         .dump           = nft_cmp16_fast_dump,
 379         .reduce         = NFT_REDUCE_READONLY,
 380         .offload        = nft_cmp16_fast_offload,
 381 };
 382
 383 static const struct nft_expr_ops *
 384 nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 385 {
 386         struct nft_data data;
 387         struct nft_data_desc desc = {
 388                 .type   = NFT_DATA_VALUE,
 389                 .size   = sizeof(data),
 390         };
 391         enum nft_cmp_ops op;
 392         u8 sreg;
 393         int err;
 394
 395         if (tb[NFTA_CMP_SREG] == NULL ||
 396             tb[NFTA_CMP_OP] == NULL ||
 397             tb[NFTA_CMP_DATA] == NULL)
 398                 return ERR_PTR(-EINVAL);
 399
 400         op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 401         switch (op) {
 402         case NFT_CMP_EQ:
 403         case NFT_CMP_NEQ:
 404         case NFT_CMP_LT:
 405         case NFT_CMP_LTE:
 406         case NFT_CMP_GT:
 407         case NFT_CMP_GTE:
 408                 break;
 409         default:
 410                 return ERR_PTR(-EINVAL);
 411         }
 412
 413         err = nft_data_init(NULL, &data, &desc, tb[NFTA_CMP_DATA]);
 414         if (err < 0)
 415                 return ERR_PTR(err);
 416
 417         sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
 418
 419         if (op == NFT_CMP_EQ || op == NFT_CMP_NEQ) {
 420                 if (desc.len <= sizeof(u32))
 421                         return &nft_cmp_fast_ops;
 422                 else if (desc.len <= sizeof(data) &&
 423                          ((sreg >= NFT_REG_1 && sreg <= NFT_REG_4) ||
 424                           (sreg >= NFT_REG32_00 && sreg <= NFT_REG32_12 && sreg % 2 == 0)))
 425                         return &nft_cmp16_fast_ops;
 426         }
 427         return &nft_cmp_ops;
 428 }
 429
 430 struct nft_expr_type nft_cmp_type __read_mostly = {
 431         .name           = "cmp",
 432         .select_ops     = nft_cmp_select_ops,
 433         .policy         = nft_cmp_policy,
 434         .maxattr        = NFTA_CMP_MAX,
 435         .owner          = THIS_MODULE,
 436 };