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
17struct nft_limit {
18 spinlock_t lock;
19 u64 last;
20 u64 tokens;
21};
22
23struct 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
32static 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(lock: &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(lock: &priv->limit->lock);
48 return priv->invert;
49 }
50 priv->limit->tokens = tokens;
51 spin_unlock_bh(lock: &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
58static 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(dividend: priv->nsecs, divisor: 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(dividend: priv->nsecs * (priv->rate + priv->burst),
90 divisor: priv->rate);
91 }
92
93 priv->limit = kmalloc(size: 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
112static 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(dividend: priv->nsecs, NSEC_PER_SEC);
117
118 if (nla_put_be64(skb, attrtype: NFTA_LIMIT_RATE, cpu_to_be64(priv->rate),
119 padattr: NFTA_LIMIT_PAD) ||
120 nla_put_be64(skb, attrtype: NFTA_LIMIT_UNIT, cpu_to_be64(secs),
121 padattr: NFTA_LIMIT_PAD) ||
122 nla_put_be32(skb, attrtype: NFTA_LIMIT_BURST, htonl(priv->burst)) ||
123 nla_put_be32(skb, attrtype: NFTA_LIMIT_TYPE, htonl(type)) ||
124 nla_put_be32(skb, attrtype: NFTA_LIMIT_FLAGS, htonl(flags)))
125 goto nla_put_failure;
126 return 0;
127
128nla_put_failure:
129 return -1;
130}
131
132static void nft_limit_destroy(const struct nft_ctx *ctx,
133 const struct nft_limit_priv *priv)
134{
135 kfree(objp: priv->limit);
136}
137
138static 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(size: 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
158struct nft_limit_priv_pkts {
159 struct nft_limit_priv limit;
160 u64 cost;
161};
162
163static 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: &priv->limit, cost: priv->cost))
170 regs->verdict.code = NFT_BREAK;
171}
172
173static 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
181static 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: &priv->limit, tb, pkts: true);
189 if (err < 0)
190 return err;
191
192 priv->cost = div64_u64(dividend: priv->limit.nsecs, divisor: priv->limit.rate);
193 return 0;
194}
195
196static 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: &priv->limit, type: NFT_LIMIT_PKTS);
202}
203
204static 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: &priv->limit);
210}
211
212static 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(expr: dst);
215 struct nft_limit_priv_pkts *priv_src = nft_expr_priv(expr: src);
216
217 priv_dst->cost = priv_src->cost;
218
219 return nft_limit_clone(priv_dst: &priv_dst->limit, priv_src: &priv_src->limit);
220}
221
222static struct nft_expr_type nft_limit_type;
223static 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
234static 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(dividend: priv->nsecs * pkt->skb->len, divisor: priv->rate);
240
241 if (nft_limit_eval(priv, cost))
242 regs->verdict.code = NFT_BREAK;
243}
244
245static 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, pkts: false);
252}
253
254static 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, type: NFT_LIMIT_PKT_BYTES);
260}
261
262static 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
270static 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(expr: dst);
273 struct nft_limit_priv *priv_src = nft_expr_priv(expr: src);
274
275 return nft_limit_clone(priv_dst, priv_src);
276}
277
278static 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
289static const struct nft_expr_ops *
290nft_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(error: -EOPNOTSUPP);
303}
304
305static 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
314static 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: &priv->limit, cost: priv->cost))
321 regs->verdict.code = NFT_BREAK;
322}
323
324static 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: &priv->limit, tb, pkts: true);
332 if (err < 0)
333 return err;
334
335 priv->cost = div64_u64(dividend: priv->limit.nsecs, divisor: priv->limit.rate);
336 return 0;
337}
338
339static 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: &priv->limit, type: NFT_LIMIT_PKTS);
346}
347
348static 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: &priv->limit);
354}
355
356static struct nft_object_type nft_limit_obj_type;
357static 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
366static 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(dividend: priv->nsecs * pkt->skb->len, divisor: priv->rate);
372
373 if (nft_limit_eval(priv, cost))
374 regs->verdict.code = NFT_BREAK;
375}
376
377static 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, pkts: false);
384}
385
386static 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, type: NFT_LIMIT_PKT_BYTES);
393}
394
395static 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
403static struct nft_object_type nft_limit_obj_type;
404static 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
413static const struct nft_object_ops *
414nft_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(error: -EOPNOTSUPP);
427}
428
429static 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
437static int __init nft_limit_module_init(void)
438{
439 int err;
440
441 err = nft_register_obj(obj_type: &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;
450err1:
451 nft_unregister_obj(obj_type: &nft_limit_obj_type);
452 return err;
453}
454
455static void __exit nft_limit_module_exit(void)
456{
457 nft_unregister_expr(&nft_limit_type);
458 nft_unregister_obj(obj_type: &nft_limit_obj_type);
459}
460
461module_init(nft_limit_module_init);
462module_exit(nft_limit_module_exit);
463
464MODULE_LICENSE("GPL");
465MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
466MODULE_ALIAS_NFT_EXPR("limit");
467MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_LIMIT);
468MODULE_DESCRIPTION("nftables limit expression support");
469

source code of linux/net/netfilter/nft_limit.c