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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 u64 tokens_max;
22 u64 rate;
23 u64 nsecs;
24 u32 burst;
25 bool invert;
26};
27
28static inline bool nft_limit_eval(struct nft_limit *limit, u64 cost)
29{
30 u64 now, tokens;
31 s64 delta;
32
33 spin_lock_bh(&limit->lock);
34 now = ktime_get_ns();
35 tokens = limit->tokens + now - limit->last;
36 if (tokens > limit->tokens_max)
37 tokens = limit->tokens_max;
38
39 limit->last = now;
40 delta = tokens - cost;
41 if (delta >= 0) {
42 limit->tokens = delta;
43 spin_unlock_bh(&limit->lock);
44 return limit->invert;
45 }
46 limit->tokens = tokens;
47 spin_unlock_bh(&limit->lock);
48 return !limit->invert;
49}
50
51/* Use same default as in iptables. */
52#define NFT_LIMIT_PKT_BURST_DEFAULT 5
53
54static int nft_limit_init(struct nft_limit *limit,
55 const struct nlattr * const tb[], bool pkts)
56{
57 u64 unit, tokens;
58
59 if (tb[NFTA_LIMIT_RATE] == NULL ||
60 tb[NFTA_LIMIT_UNIT] == NULL)
61 return -EINVAL;
62
63 limit->rate = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_RATE]));
64 unit = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_UNIT]));
65 limit->nsecs = unit * NSEC_PER_SEC;
66 if (limit->rate == 0 || limit->nsecs < unit)
67 return -EOVERFLOW;
68
69 if (tb[NFTA_LIMIT_BURST])
70 limit->burst = ntohl(nla_get_be32(tb[NFTA_LIMIT_BURST]));
71
72 if (pkts && limit->burst == 0)
73 limit->burst = NFT_LIMIT_PKT_BURST_DEFAULT;
74
75 if (limit->rate + limit->burst < limit->rate)
76 return -EOVERFLOW;
77
78 if (pkts) {
79 tokens = div64_u64(limit->nsecs, limit->rate) * limit->burst;
80 } else {
81 /* The token bucket size limits the number of tokens can be
82 * accumulated. tokens_max specifies the bucket size.
83 * tokens_max = unit * (rate + burst) / rate.
84 */
85 tokens = div64_u64(limit->nsecs * (limit->rate + limit->burst),
86 limit->rate);
87 }
88
89 limit->tokens = tokens;
90 limit->tokens_max = limit->tokens;
91
92 if (tb[NFTA_LIMIT_FLAGS]) {
93 u32 flags = ntohl(nla_get_be32(tb[NFTA_LIMIT_FLAGS]));
94
95 if (flags & NFT_LIMIT_F_INV)
96 limit->invert = true;
97 }
98 limit->last = ktime_get_ns();
99 spin_lock_init(&limit->lock);
100
101 return 0;
102}
103
104static int nft_limit_dump(struct sk_buff *skb, const struct nft_limit *limit,
105 enum nft_limit_type type)
106{
107 u32 flags = limit->invert ? NFT_LIMIT_F_INV : 0;
108 u64 secs = div_u64(limit->nsecs, NSEC_PER_SEC);
109
110 if (nla_put_be64(skb, NFTA_LIMIT_RATE, cpu_to_be64(limit->rate),
111 NFTA_LIMIT_PAD) ||
112 nla_put_be64(skb, NFTA_LIMIT_UNIT, cpu_to_be64(secs),
113 NFTA_LIMIT_PAD) ||
114 nla_put_be32(skb, NFTA_LIMIT_BURST, htonl(limit->burst)) ||
115 nla_put_be32(skb, NFTA_LIMIT_TYPE, htonl(type)) ||
116 nla_put_be32(skb, NFTA_LIMIT_FLAGS, htonl(flags)))
117 goto nla_put_failure;
118 return 0;
119
120nla_put_failure:
121 return -1;
122}
123
124struct nft_limit_pkts {
125 struct nft_limit limit;
126 u64 cost;
127};
128
129static void nft_limit_pkts_eval(const struct nft_expr *expr,
130 struct nft_regs *regs,
131 const struct nft_pktinfo *pkt)
132{
133 struct nft_limit_pkts *priv = nft_expr_priv(expr);
134
135 if (nft_limit_eval(&priv->limit, priv->cost))
136 regs->verdict.code = NFT_BREAK;
137}
138
139static const struct nla_policy nft_limit_policy[NFTA_LIMIT_MAX + 1] = {
140 [NFTA_LIMIT_RATE] = { .type = NLA_U64 },
141 [NFTA_LIMIT_UNIT] = { .type = NLA_U64 },
142 [NFTA_LIMIT_BURST] = { .type = NLA_U32 },
143 [NFTA_LIMIT_TYPE] = { .type = NLA_U32 },
144 [NFTA_LIMIT_FLAGS] = { .type = NLA_U32 },
145};
146
147static int nft_limit_pkts_init(const struct nft_ctx *ctx,
148 const struct nft_expr *expr,
149 const struct nlattr * const tb[])
150{
151 struct nft_limit_pkts *priv = nft_expr_priv(expr);
152 int err;
153
154 err = nft_limit_init(&priv->limit, tb, true);
155 if (err < 0)
156 return err;
157
158 priv->cost = div64_u64(priv->limit.nsecs, priv->limit.rate);
159 return 0;
160}
161
162static int nft_limit_pkts_dump(struct sk_buff *skb, const struct nft_expr *expr)
163{
164 const struct nft_limit_pkts *priv = nft_expr_priv(expr);
165
166 return nft_limit_dump(skb, &priv->limit, NFT_LIMIT_PKTS);
167}
168
169static struct nft_expr_type nft_limit_type;
170static const struct nft_expr_ops nft_limit_pkts_ops = {
171 .type = &nft_limit_type,
172 .size = NFT_EXPR_SIZE(sizeof(struct nft_limit_pkts)),
173 .eval = nft_limit_pkts_eval,
174 .init = nft_limit_pkts_init,
175 .dump = nft_limit_pkts_dump,
176};
177
178static void nft_limit_bytes_eval(const struct nft_expr *expr,
179 struct nft_regs *regs,
180 const struct nft_pktinfo *pkt)
181{
182 struct nft_limit *priv = nft_expr_priv(expr);
183 u64 cost = div64_u64(priv->nsecs * pkt->skb->len, priv->rate);
184
185 if (nft_limit_eval(priv, cost))
186 regs->verdict.code = NFT_BREAK;
187}
188
189static int nft_limit_bytes_init(const struct nft_ctx *ctx,
190 const struct nft_expr *expr,
191 const struct nlattr * const tb[])
192{
193 struct nft_limit *priv = nft_expr_priv(expr);
194
195 return nft_limit_init(priv, tb, false);
196}
197
198static int nft_limit_bytes_dump(struct sk_buff *skb,
199 const struct nft_expr *expr)
200{
201 const struct nft_limit *priv = nft_expr_priv(expr);
202
203 return nft_limit_dump(skb, priv, NFT_LIMIT_PKT_BYTES);
204}
205
206static const struct nft_expr_ops nft_limit_bytes_ops = {
207 .type = &nft_limit_type,
208 .size = NFT_EXPR_SIZE(sizeof(struct nft_limit)),
209 .eval = nft_limit_bytes_eval,
210 .init = nft_limit_bytes_init,
211 .dump = nft_limit_bytes_dump,
212};
213
214static const struct nft_expr_ops *
215nft_limit_select_ops(const struct nft_ctx *ctx,
216 const struct nlattr * const tb[])
217{
218 if (tb[NFTA_LIMIT_TYPE] == NULL)
219 return &nft_limit_pkts_ops;
220
221 switch (ntohl(nla_get_be32(tb[NFTA_LIMIT_TYPE]))) {
222 case NFT_LIMIT_PKTS:
223 return &nft_limit_pkts_ops;
224 case NFT_LIMIT_PKT_BYTES:
225 return &nft_limit_bytes_ops;
226 }
227 return ERR_PTR(-EOPNOTSUPP);
228}
229
230static struct nft_expr_type nft_limit_type __read_mostly = {
231 .name = "limit",
232 .select_ops = nft_limit_select_ops,
233 .policy = nft_limit_policy,
234 .maxattr = NFTA_LIMIT_MAX,
235 .flags = NFT_EXPR_STATEFUL,
236 .owner = THIS_MODULE,
237};
238
239static void nft_limit_obj_pkts_eval(struct nft_object *obj,
240 struct nft_regs *regs,
241 const struct nft_pktinfo *pkt)
242{
243 struct nft_limit_pkts *priv = nft_obj_data(obj);
244
245 if (nft_limit_eval(&priv->limit, priv->cost))
246 regs->verdict.code = NFT_BREAK;
247}
248
249static int nft_limit_obj_pkts_init(const struct nft_ctx *ctx,
250 const struct nlattr * const tb[],
251 struct nft_object *obj)
252{
253 struct nft_limit_pkts *priv = nft_obj_data(obj);
254 int err;
255
256 err = nft_limit_init(&priv->limit, tb, true);
257 if (err < 0)
258 return err;
259
260 priv->cost = div64_u64(priv->limit.nsecs, priv->limit.rate);
261 return 0;
262}
263
264static int nft_limit_obj_pkts_dump(struct sk_buff *skb,
265 struct nft_object *obj,
266 bool reset)
267{
268 const struct nft_limit_pkts *priv = nft_obj_data(obj);
269
270 return nft_limit_dump(skb, &priv->limit, NFT_LIMIT_PKTS);
271}
272
273static struct nft_object_type nft_limit_obj_type;
274static const struct nft_object_ops nft_limit_obj_pkts_ops = {
275 .type = &nft_limit_obj_type,
276 .size = NFT_EXPR_SIZE(sizeof(struct nft_limit_pkts)),
277 .init = nft_limit_obj_pkts_init,
278 .eval = nft_limit_obj_pkts_eval,
279 .dump = nft_limit_obj_pkts_dump,
280};
281
282static void nft_limit_obj_bytes_eval(struct nft_object *obj,
283 struct nft_regs *regs,
284 const struct nft_pktinfo *pkt)
285{
286 struct nft_limit *priv = nft_obj_data(obj);
287 u64 cost = div64_u64(priv->nsecs * pkt->skb->len, priv->rate);
288
289 if (nft_limit_eval(priv, cost))
290 regs->verdict.code = NFT_BREAK;
291}
292
293static int nft_limit_obj_bytes_init(const struct nft_ctx *ctx,
294 const struct nlattr * const tb[],
295 struct nft_object *obj)
296{
297 struct nft_limit *priv = nft_obj_data(obj);
298
299 return nft_limit_init(priv, tb, false);
300}
301
302static int nft_limit_obj_bytes_dump(struct sk_buff *skb,
303 struct nft_object *obj,
304 bool reset)
305{
306 const struct nft_limit *priv = nft_obj_data(obj);
307
308 return nft_limit_dump(skb, priv, NFT_LIMIT_PKT_BYTES);
309}
310
311static struct nft_object_type nft_limit_obj_type;
312static const struct nft_object_ops nft_limit_obj_bytes_ops = {
313 .type = &nft_limit_obj_type,
314 .size = sizeof(struct nft_limit),
315 .init = nft_limit_obj_bytes_init,
316 .eval = nft_limit_obj_bytes_eval,
317 .dump = nft_limit_obj_bytes_dump,
318};
319
320static const struct nft_object_ops *
321nft_limit_obj_select_ops(const struct nft_ctx *ctx,
322 const struct nlattr * const tb[])
323{
324 if (!tb[NFTA_LIMIT_TYPE])
325 return &nft_limit_obj_pkts_ops;
326
327 switch (ntohl(nla_get_be32(tb[NFTA_LIMIT_TYPE]))) {
328 case NFT_LIMIT_PKTS:
329 return &nft_limit_obj_pkts_ops;
330 case NFT_LIMIT_PKT_BYTES:
331 return &nft_limit_obj_bytes_ops;
332 }
333 return ERR_PTR(-EOPNOTSUPP);
334}
335
336static struct nft_object_type nft_limit_obj_type __read_mostly = {
337 .select_ops = nft_limit_obj_select_ops,
338 .type = NFT_OBJECT_LIMIT,
339 .maxattr = NFTA_LIMIT_MAX,
340 .policy = nft_limit_policy,
341 .owner = THIS_MODULE,
342};
343
344static int __init nft_limit_module_init(void)
345{
346 int err;
347
348 err = nft_register_obj(&nft_limit_obj_type);
349 if (err < 0)
350 return err;
351
352 err = nft_register_expr(&nft_limit_type);
353 if (err < 0)
354 goto err1;
355
356 return 0;
357err1:
358 nft_unregister_obj(&nft_limit_obj_type);
359 return err;
360}
361
362static void __exit nft_limit_module_exit(void)
363{
364 nft_unregister_expr(&nft_limit_type);
365 nft_unregister_obj(&nft_limit_obj_type);
366}
367
368module_init(nft_limit_module_init);
369module_exit(nft_limit_module_exit);
370
371MODULE_LICENSE("GPL");
372MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
373MODULE_ALIAS_NFT_EXPR("limit");
374MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_LIMIT);
375MODULE_DESCRIPTION("nftables limit expression support");