net/netfilter/nft_limit.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/spinlock.h>
  12 #include <linux/netlink.h>
  13 #include <linux/netfilter.h>
  14 #include <linux/netfilter/nf_tables.h>
  15 #include <net/netfilter/nf_tables.h>
  16
  17 struct nft_limit {
  18         spinlock_t      lock;
  19         u64             last;
  20         u64             tokens;
  21 };
  22
  23 struct nft_limit_priv {
  24         struct nft_limit *limit;
  25         u64             tokens_max;
  26         u64             rate;
  27         u64             nsecs;
  28         u32             burst;
  29         bool            invert;
  30 };
  31
  32 static inline bool nft_limit_eval(struct nft_limit_priv *priv, u64 cost)
  33 {
  34         u64 now, tokens;
  35         s64 delta;
  36
  37         spin_lock_bh(&priv->limit->lock);
  38         now = ktime_get_ns();
  39         tokens = priv->limit->tokens + now - priv->limit->last;
  40         if (tokens > priv->tokens_max)
  41                 tokens = priv->tokens_max;
  42
  43         priv->limit->last = now;
  44         delta = tokens - cost;
  45         if (delta >= 0) {
  46                 priv->limit->tokens = delta;
  47                 spin_unlock_bh(&priv->limit->lock);
  48                 return priv->invert;
  49         }
  50         priv->limit->tokens = tokens;
  51         spin_unlock_bh(&priv->limit->lock);
  52         return !priv->invert;
  53 }
  54
  55 /* Use same default as in iptables. */
  56 #define NFT_LIMIT_PKT_BURST_DEFAULT     5
  57
  58 static int nft_limit_init(struct nft_limit_priv *priv,
  59                           const struct nlattr * const tb[], bool pkts)
  60 {
  61         u64 unit, tokens, rate_with_burst;
  62         bool invert = false;
  63
  64         if (tb[NFTA_LIMIT_RATE] == NULL ||
  65             tb[NFTA_LIMIT_UNIT] == NULL)
  66                 return -EINVAL;
  67
  68         priv->rate = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_RATE]));
  69         if (priv->rate == 0)
  70                 return -EINVAL;
  71
  72         unit = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_UNIT]));
  73         if (check_mul_overflow(unit, NSEC_PER_SEC, &priv->nsecs))
  74                 return -EOVERFLOW;
  75
  76         if (tb[NFTA_LIMIT_BURST])
  77                 priv->burst = ntohl(nla_get_be32(tb[NFTA_LIMIT_BURST]));
  78
  79         if (pkts && priv->burst == 0)
  80                 priv->burst = NFT_LIMIT_PKT_BURST_DEFAULT;
  81
  82         if (check_add_overflow(priv->rate, priv->burst, &rate_with_burst))
  83                 return -EOVERFLOW;
  84
  85         if (pkts) {
  86                 u64 tmp = div64_u64(priv->nsecs, priv->rate);
  87
  88                 if (check_mul_overflow(tmp, priv->burst, &tokens))
  89                         return -EOVERFLOW;
  90         } else {
  91                 u64 tmp;
  92
  93                 /* The token bucket size limits the number of tokens can be
  94                  * accumulated. tokens_max specifies the bucket size.
  95                  * tokens_max = unit * (rate + burst) / rate.
  96                  */
  97                 if (check_mul_overflow(priv->nsecs, rate_with_burst, &tmp))
  98                         return -EOVERFLOW;
  99
 100                 tokens = div64_u64(tmp, priv->rate);
 101         }
 102
 103         if (tb[NFTA_LIMIT_FLAGS]) {
 104                 u32 flags = ntohl(nla_get_be32(tb[NFTA_LIMIT_FLAGS]));
 105
 106                 if (flags & ~NFT_LIMIT_F_INV)
 107                         return -EOPNOTSUPP;
 108
 109                 if (flags & NFT_LIMIT_F_INV)
 110                         invert = true;
 111         }
 112
 113         priv->limit = kmalloc(sizeof(*priv->limit), GFP_KERNEL_ACCOUNT);
 114         if (!priv->limit)
 115                 return -ENOMEM;
 116
 117         priv->limit->tokens = tokens;
 118         priv->tokens_max = priv->limit->tokens;
 119         priv->invert = invert;
 120         priv->limit->last = ktime_get_ns();
 121         spin_lock_init(&priv->limit->lock);
 122
 123         return 0;
 124 }
 125
 126 static int nft_limit_dump(struct sk_buff *skb, const struct nft_limit_priv *priv,
 127                           enum nft_limit_type type)
 128 {
 129         u32 flags = priv->invert ? NFT_LIMIT_F_INV : 0;
 130         u64 secs = div_u64(priv->nsecs, NSEC_PER_SEC);
 131
 132         if (nla_put_be64(skb, NFTA_LIMIT_RATE, cpu_to_be64(priv->rate),
 133                          NFTA_LIMIT_PAD) ||
 134             nla_put_be64(skb, NFTA_LIMIT_UNIT, cpu_to_be64(secs),
 135                          NFTA_LIMIT_PAD) ||
 136             nla_put_be32(skb, NFTA_LIMIT_BURST, htonl(priv->burst)) ||
 137             nla_put_be32(skb, NFTA_LIMIT_TYPE, htonl(type)) ||
 138             nla_put_be32(skb, NFTA_LIMIT_FLAGS, htonl(flags)))
 139                 goto nla_put_failure;
 140         return 0;
 141
 142 nla_put_failure:
 143         return -1;
 144 }
 145
 146 static void nft_limit_destroy(const struct nft_ctx *ctx,
 147                               const struct nft_limit_priv *priv)
 148 {
 149         kfree(priv->limit);
 150 }
 151
 152 static int nft_limit_clone(struct nft_limit_priv *priv_dst,
 153                            const struct nft_limit_priv *priv_src, gfp_t gfp)
 154 {
 155         priv_dst->tokens_max = priv_src->tokens_max;
 156         priv_dst->rate = priv_src->rate;
 157         priv_dst->nsecs = priv_src->nsecs;
 158         priv_dst->burst = priv_src->burst;
 159         priv_dst->invert = priv_src->invert;
 160
 161         priv_dst->limit = kmalloc(sizeof(*priv_dst->limit), gfp);
 162         if (!priv_dst->limit)
 163                 return -ENOMEM;
 164
 165         spin_lock_init(&priv_dst->limit->lock);
 166         priv_dst->limit->tokens = priv_src->tokens_max;
 167         priv_dst->limit->last = ktime_get_ns();
 168
 169         return 0;
 170 }
 171
 172 struct nft_limit_priv_pkts {
 173         struct nft_limit_priv   limit;
 174         u64                     cost;
 175 };
 176
 177 static void nft_limit_pkts_eval(const struct nft_expr *expr,
 178                                 struct nft_regs *regs,
 179                                 const struct nft_pktinfo *pkt)
 180 {
 181         struct nft_limit_priv_pkts *priv = nft_expr_priv(expr);
 182
 183         if (nft_limit_eval(&priv->limit, priv->cost))
 184                 regs->verdict.code = NFT_BREAK;
 185 }
 186
 187 static const struct nla_policy nft_limit_policy[NFTA_LIMIT_MAX + 1] = {
 188         [NFTA_LIMIT_RATE]       = { .type = NLA_U64 },
 189         [NFTA_LIMIT_UNIT]       = { .type = NLA_U64 },
 190         [NFTA_LIMIT_BURST]      = { .type = NLA_U32 },
 191         [NFTA_LIMIT_TYPE]       = { .type = NLA_U32 },
 192         [NFTA_LIMIT_FLAGS]      = { .type = NLA_U32 },
 193 };
 194
 195 static int nft_limit_pkts_init(const struct nft_ctx *ctx,
 196                                const struct nft_expr *expr,
 197                                const struct nlattr * const tb[])
 198 {
 199         struct nft_limit_priv_pkts *priv = nft_expr_priv(expr);
 200         int err;
 201
 202         err = nft_limit_init(&priv->limit, tb, true);
 203         if (err < 0)
 204                 return err;
 205
 206         priv->cost = div64_u64(priv->limit.nsecs, priv->limit.rate);
 207         return 0;
 208 }
 209
 210 static int nft_limit_pkts_dump(struct sk_buff *skb,
 211                                const struct nft_expr *expr, bool reset)
 212 {
 213         const struct nft_limit_priv_pkts *priv = nft_expr_priv(expr);
 214
 215         return nft_limit_dump(skb, &priv->limit, NFT_LIMIT_PKTS);
 216 }
 217
 218 static void nft_limit_pkts_destroy(const struct nft_ctx *ctx,
 219                                    const struct nft_expr *expr)
 220 {
 221         const struct nft_limit_priv_pkts *priv = nft_expr_priv(expr);
 222
 223         nft_limit_destroy(ctx, &priv->limit);
 224 }
 225
 226 static int nft_limit_pkts_clone(struct nft_expr *dst, const struct nft_expr *src,
 227                                 gfp_t gfp)
 228 {
 229         struct nft_limit_priv_pkts *priv_dst = nft_expr_priv(dst);
 230         struct nft_limit_priv_pkts *priv_src = nft_expr_priv(src);
 231
 232         priv_dst->cost = priv_src->cost;
 233
 234         return nft_limit_clone(&priv_dst->limit, &priv_src->limit, gfp);
 235 }
 236
 237 static struct nft_expr_type nft_limit_type;
 238 static const struct nft_expr_ops nft_limit_pkts_ops = {
 239         .type           = &nft_limit_type,
 240         .size           = NFT_EXPR_SIZE(sizeof(struct nft_limit_priv_pkts)),
 241         .eval           = nft_limit_pkts_eval,
 242         .init           = nft_limit_pkts_init,
 243         .destroy        = nft_limit_pkts_destroy,
 244         .clone          = nft_limit_pkts_clone,
 245         .dump           = nft_limit_pkts_dump,
 246         .reduce         = NFT_REDUCE_READONLY,
 247 };
 248
 249 static void nft_limit_bytes_eval(const struct nft_expr *expr,
 250                                  struct nft_regs *regs,
 251                                  const struct nft_pktinfo *pkt)
 252 {
 253         struct nft_limit_priv *priv = nft_expr_priv(expr);
 254         u64 cost = div64_u64(priv->nsecs * pkt->skb->len, priv->rate);
 255
 256         if (nft_limit_eval(priv, cost))
 257                 regs->verdict.code = NFT_BREAK;
 258 }
 259
 260 static int nft_limit_bytes_init(const struct nft_ctx *ctx,
 261                                 const struct nft_expr *expr,
 262                                 const struct nlattr * const tb[])
 263 {
 264         struct nft_limit_priv *priv = nft_expr_priv(expr);
 265
 266         return nft_limit_init(priv, tb, false);
 267 }
 268
 269 static int nft_limit_bytes_dump(struct sk_buff *skb,
 270                                 const struct nft_expr *expr, bool reset)
 271 {
 272         const struct nft_limit_priv *priv = nft_expr_priv(expr);
 273
 274         return nft_limit_dump(skb, priv, NFT_LIMIT_PKT_BYTES);
 275 }
 276
 277 static void nft_limit_bytes_destroy(const struct nft_ctx *ctx,
 278                                     const struct nft_expr *expr)
 279 {
 280         const struct nft_limit_priv *priv = nft_expr_priv(expr);
 281
 282         nft_limit_destroy(ctx, priv);
 283 }
 284
 285 static int nft_limit_bytes_clone(struct nft_expr *dst, const struct nft_expr *src,
 286                                  gfp_t gfp)
 287 {
 288         struct nft_limit_priv *priv_dst = nft_expr_priv(dst);
 289         struct nft_limit_priv *priv_src = nft_expr_priv(src);
 290
 291         return nft_limit_clone(priv_dst, priv_src, gfp);
 292 }
 293
 294 static const struct nft_expr_ops nft_limit_bytes_ops = {
 295         .type           = &nft_limit_type,
 296         .size           = NFT_EXPR_SIZE(sizeof(struct nft_limit_priv)),
 297         .eval           = nft_limit_bytes_eval,
 298         .init           = nft_limit_bytes_init,
 299         .dump           = nft_limit_bytes_dump,
 300         .clone          = nft_limit_bytes_clone,
 301         .destroy        = nft_limit_bytes_destroy,
 302         .reduce         = NFT_REDUCE_READONLY,
 303 };
 304
 305 static const struct nft_expr_ops *
 306 nft_limit_select_ops(const struct nft_ctx *ctx,
 307                      const struct nlattr * const tb[])
 308 {
 309         if (tb[NFTA_LIMIT_TYPE] == NULL)
 310                 return &nft_limit_pkts_ops;
 311
 312         switch (ntohl(nla_get_be32(tb[NFTA_LIMIT_TYPE]))) {
 313         case NFT_LIMIT_PKTS:
 314                 return &nft_limit_pkts_ops;
 315         case NFT_LIMIT_PKT_BYTES:
 316                 return &nft_limit_bytes_ops;
 317         }
 318         return ERR_PTR(-EOPNOTSUPP);
 319 }
 320
 321 static struct nft_expr_type nft_limit_type __read_mostly = {
 322         .name           = "limit",
 323         .select_ops     = nft_limit_select_ops,
 324         .policy         = nft_limit_policy,
 325         .maxattr        = NFTA_LIMIT_MAX,
 326         .flags          = NFT_EXPR_STATEFUL,
 327         .owner          = THIS_MODULE,
 328 };
 329
 330 static void nft_limit_obj_pkts_eval(struct nft_object *obj,
 331                                     struct nft_regs *regs,
 332                                     const struct nft_pktinfo *pkt)
 333 {
 334         struct nft_limit_priv_pkts *priv = nft_obj_data(obj);
 335
 336         if (nft_limit_eval(&priv->limit, priv->cost))
 337                 regs->verdict.code = NFT_BREAK;
 338 }
 339
 340 static int nft_limit_obj_pkts_init(const struct nft_ctx *ctx,
 341                                    const struct nlattr * const tb[],
 342                                    struct nft_object *obj)
 343 {
 344         struct nft_limit_priv_pkts *priv = nft_obj_data(obj);
 345         int err;
 346
 347         err = nft_limit_init(&priv->limit, tb, true);
 348         if (err < 0)
 349                 return err;
 350
 351         priv->cost = div64_u64(priv->limit.nsecs, priv->limit.rate);
 352         return 0;
 353 }
 354
 355 static int nft_limit_obj_pkts_dump(struct sk_buff *skb,
 356                                    struct nft_object *obj,
 357                                    bool reset)
 358 {
 359         const struct nft_limit_priv_pkts *priv = nft_obj_data(obj);
 360
 361         return nft_limit_dump(skb, &priv->limit, NFT_LIMIT_PKTS);
 362 }
 363
 364 static void nft_limit_obj_pkts_destroy(const struct nft_ctx *ctx,
 365                                        struct nft_object *obj)
 366 {
 367         struct nft_limit_priv_pkts *priv = nft_obj_data(obj);
 368
 369         nft_limit_destroy(ctx, &priv->limit);
 370 }
 371
 372 static struct nft_object_type nft_limit_obj_type;
 373 static const struct nft_object_ops nft_limit_obj_pkts_ops = {
 374         .type           = &nft_limit_obj_type,
 375         .size           = NFT_EXPR_SIZE(sizeof(struct nft_limit_priv_pkts)),
 376         .init           = nft_limit_obj_pkts_init,
 377         .destroy        = nft_limit_obj_pkts_destroy,
 378         .eval           = nft_limit_obj_pkts_eval,
 379         .dump           = nft_limit_obj_pkts_dump,
 380 };
 381
 382 static void nft_limit_obj_bytes_eval(struct nft_object *obj,
 383                                      struct nft_regs *regs,
 384                                      const struct nft_pktinfo *pkt)
 385 {
 386         struct nft_limit_priv *priv = nft_obj_data(obj);
 387         u64 cost = div64_u64(priv->nsecs * pkt->skb->len, priv->rate);
 388
 389         if (nft_limit_eval(priv, cost))
 390                 regs->verdict.code = NFT_BREAK;
 391 }
 392
 393 static int nft_limit_obj_bytes_init(const struct nft_ctx *ctx,
 394                                     const struct nlattr * const tb[],
 395                                     struct nft_object *obj)
 396 {
 397         struct nft_limit_priv *priv = nft_obj_data(obj);
 398
 399         return nft_limit_init(priv, tb, false);
 400 }
 401
 402 static int nft_limit_obj_bytes_dump(struct sk_buff *skb,
 403                                     struct nft_object *obj,
 404                                     bool reset)
 405 {
 406         const struct nft_limit_priv *priv = nft_obj_data(obj);
 407
 408         return nft_limit_dump(skb, priv, NFT_LIMIT_PKT_BYTES);
 409 }
 410
 411 static void nft_limit_obj_bytes_destroy(const struct nft_ctx *ctx,
 412                                         struct nft_object *obj)
 413 {
 414         struct nft_limit_priv *priv = nft_obj_data(obj);
 415
 416         nft_limit_destroy(ctx, priv);
 417 }
 418
 419 static struct nft_object_type nft_limit_obj_type;
 420 static const struct nft_object_ops nft_limit_obj_bytes_ops = {
 421         .type           = &nft_limit_obj_type,
 422         .size           = sizeof(struct nft_limit_priv),
 423         .init           = nft_limit_obj_bytes_init,
 424         .destroy        = nft_limit_obj_bytes_destroy,
 425         .eval           = nft_limit_obj_bytes_eval,
 426         .dump           = nft_limit_obj_bytes_dump,
 427 };
 428
 429 static const struct nft_object_ops *
 430 nft_limit_obj_select_ops(const struct nft_ctx *ctx,
 431                          const struct nlattr * const tb[])
 432 {
 433         if (!tb[NFTA_LIMIT_TYPE])
 434                 return &nft_limit_obj_pkts_ops;
 435
 436         switch (ntohl(nla_get_be32(tb[NFTA_LIMIT_TYPE]))) {
 437         case NFT_LIMIT_PKTS:
 438                 return &nft_limit_obj_pkts_ops;
 439         case NFT_LIMIT_PKT_BYTES:
 440                 return &nft_limit_obj_bytes_ops;
 441         }
 442         return ERR_PTR(-EOPNOTSUPP);
 443 }
 444
 445 static struct nft_object_type nft_limit_obj_type __read_mostly = {
 446         .select_ops     = nft_limit_obj_select_ops,
 447         .type           = NFT_OBJECT_LIMIT,
 448         .maxattr        = NFTA_LIMIT_MAX,
 449         .policy         = nft_limit_policy,
 450         .owner          = THIS_MODULE,
 451 };
 452
 453 static int __init nft_limit_module_init(void)
 454 {
 455         int err;
 456
 457         err = nft_register_obj(&nft_limit_obj_type);
 458         if (err < 0)
 459                 return err;
 460
 461         err = nft_register_expr(&nft_limit_type);
 462         if (err < 0)
 463                 goto err1;
 464
 465         return 0;
 466 err1:
 467         nft_unregister_obj(&nft_limit_obj_type);
 468         return err;
 469 }
 470
 471 static void __exit nft_limit_module_exit(void)
 472 {
 473         nft_unregister_expr(&nft_limit_type);
 474         nft_unregister_obj(&nft_limit_obj_type);
 475 }
 476
 477 module_init(nft_limit_module_init);
 478 module_exit(nft_limit_module_exit);
 479
 480 MODULE_LICENSE("GPL");
 481 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 482 MODULE_ALIAS_NFT_EXPR("limit");
 483 MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_LIMIT);
 484 MODULE_DESCRIPTION("nftables limit expression support");