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