summaryrefslogtreecommitdiff
path: root/net/netfilter/nft_limit.c
blob: 35b67d7e3694766744cdb41aa7b57fcee5370711 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>

struct nft_limit {
	spinlock_t	lock;
	u64		last;
	u64		tokens;
	u64		tokens_max;
	u64		rate;
	u64		nsecs;
	u32		burst;
	bool		invert;
};

static inline bool nft_limit_eval(struct nft_limit *limit, u64 cost)
{
	u64 now, tokens;
	s64 delta;

	spin_lock_bh(&limit->lock);
	now = ktime_get_ns();
	tokens = limit->tokens + now - limit->last;
	if (tokens > limit->tokens_max)
		tokens = limit->tokens_max;

	limit->last = now;
	delta = tokens - cost;
	if (delta >= 0) {
		limit->tokens = delta;
		spin_unlock_bh(&limit->lock);
		return limit->invert;
	}
	limit->tokens = tokens;
	spin_unlock_bh(&limit->lock);
	return !limit->invert;
}

/* Use same default as in iptables. */
#define NFT_LIMIT_PKT_BURST_DEFAULT	5

static int nft_limit_init(struct nft_limit *limit,
			  const struct nlattr * const tb[], bool pkts)
{
	u64 unit, tokens;

	if (tb[NFTA_LIMIT_RATE] == NULL ||
	    tb[NFTA_LIMIT_UNIT] == NULL)
		return -EINVAL;

	limit->rate = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_RATE]));
	unit = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_UNIT]));
	limit->nsecs = unit * NSEC_PER_SEC;
	if (limit->rate == 0 || limit->nsecs < unit)
		return -EOVERFLOW;

	if (tb[NFTA_LIMIT_BURST])
		limit->burst = ntohl(nla_get_be32(tb[NFTA_LIMIT_BURST]));

	if (pkts && limit->burst == 0)
		limit->burst = NFT_LIMIT_PKT_BURST_DEFAULT;

	if (limit->rate + limit->burst < limit->rate)
		return -EOVERFLOW;

	if (pkts) {
		tokens = div_u64(limit->nsecs, limit->rate) * limit->burst;
	} else {
		/* The token bucket size limits the number of tokens can be
		 * accumulated. tokens_max specifies the bucket size.
		 * tokens_max = unit * (rate + burst) / rate.
		 */
		tokens = div_u64(limit->nsecs * (limit->rate + limit->burst),
				 limit->rate);
	}

	limit->tokens = tokens;
	limit->tokens_max = limit->tokens;

	if (tb[NFTA_LIMIT_FLAGS]) {
		u32 flags = ntohl(nla_get_be32(tb[NFTA_LIMIT_FLAGS]));

		if (flags & NFT_LIMIT_F_INV)
			limit->invert = true;
	}
	limit->last = ktime_get_ns();
	spin_lock_init(&limit->lock);

	return 0;
}

static int nft_limit_dump(struct sk_buff *skb, const struct nft_limit *limit,
			  enum nft_limit_type type)
{
	u32 flags = limit->invert ? NFT_LIMIT_F_INV : 0;
	u64 secs = div_u64(limit->nsecs, NSEC_PER_SEC);

	if (nla_put_be64(skb, NFTA_LIMIT_RATE, cpu_to_be64(limit->rate),
			 NFTA_LIMIT_PAD) ||
	    nla_put_be64(skb, NFTA_LIMIT_UNIT, cpu_to_be64(secs),
			 NFTA_LIMIT_PAD) ||
	    nla_put_be32(skb, NFTA_LIMIT_BURST, htonl(limit->burst)) ||
	    nla_put_be32(skb, NFTA_LIMIT_TYPE, htonl(type)) ||
	    nla_put_be32(skb, NFTA_LIMIT_FLAGS, htonl(flags)))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -1;
}

struct nft_limit_pkts {
	struct nft_limit	limit;
	u64			cost;
};

static void nft_limit_pkts_eval(const struct nft_expr *expr,
				struct nft_regs *regs,
				const struct nft_pktinfo *pkt)
{
	struct nft_limit_pkts *priv = nft_expr_priv(expr);

	if (nft_limit_eval(&priv->limit, priv->cost))
		regs->verdict.code = NFT_BREAK;
}

static const struct nla_policy nft_limit_policy[NFTA_LIMIT_MAX + 1] = {
	[NFTA_LIMIT_RATE]	= { .type = NLA_U64 },
	[NFTA_LIMIT_UNIT]	= { .type = NLA_U64 },
	[NFTA_LIMIT_BURST]	= { .type = NLA_U32 },
	[NFTA_LIMIT_TYPE]	= { .type = NLA_U32 },
	[NFTA_LIMIT_FLAGS]	= { .type = NLA_U32 },
};

static int nft_limit_pkts_init(const struct nft_ctx *ctx,
			       const struct nft_expr *expr,
			       const struct nlattr * const tb[])
{
	struct nft_limit_pkts *priv = nft_expr_priv(expr);
	int err;

	err = nft_limit_init(&priv->limit, tb, true);
	if (err < 0)
		return err;

	priv->cost = div64_u64(priv->limit.nsecs, priv->limit.rate);
	return 0;
}

static int nft_limit_pkts_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
	const struct nft_limit_pkts *priv = nft_expr_priv(expr);

	return nft_limit_dump(skb, &priv->limit, NFT_LIMIT_PKTS);
}

static struct nft_expr_type nft_limit_type;
static const struct nft_expr_ops nft_limit_pkts_ops = {
	.type		= &nft_limit_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_limit_pkts)),
	.eval		= nft_limit_pkts_eval,
	.init		= nft_limit_pkts_init,
	.dump		= nft_limit_pkts_dump,
};

static void nft_limit_bytes_eval(const struct nft_expr *expr,
				 struct nft_regs *regs,
				 const struct nft_pktinfo *pkt)
{
	struct nft_limit *priv = nft_expr_priv(expr);
	u64 cost = div64_u64(priv->nsecs * pkt->skb->len, priv->rate);

	if (nft_limit_eval(priv, cost))
		regs->verdict.code = NFT_BREAK;
}

static int nft_limit_bytes_init(const struct nft_ctx *ctx,
				const struct nft_expr *expr,
				const struct nlattr * const tb[])
{
	struct nft_limit *priv = nft_expr_priv(expr);

	return nft_limit_init(priv, tb, false);
}

static int nft_limit_bytes_dump(struct sk_buff *skb,
				const struct nft_expr *expr)
{
	const struct nft_limit *priv = nft_expr_priv(expr);

	return nft_limit_dump(skb, priv, NFT_LIMIT_PKT_BYTES);
}

static const struct nft_expr_ops nft_limit_bytes_ops = {
	.type		= &nft_limit_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_limit)),
	.eval		= nft_limit_bytes_eval,
	.init		= nft_limit_bytes_init,
	.dump		= nft_limit_bytes_dump,
};

static const struct nft_expr_ops *
nft_limit_select_ops(const struct nft_ctx *ctx,
		     const struct nlattr * const tb[])
{
	if (tb[NFTA_LIMIT_TYPE] == NULL)
		return &nft_limit_pkts_ops;

	switch (ntohl(nla_get_be32(tb[NFTA_LIMIT_TYPE]))) {
	case NFT_LIMIT_PKTS:
		return &nft_limit_pkts_ops;
	case NFT_LIMIT_PKT_BYTES:
		return &nft_limit_bytes_ops;
	}
	return ERR_PTR(-EOPNOTSUPP);
}

static struct nft_expr_type nft_limit_type __read_mostly = {
	.name		= "limit",
	.select_ops	= nft_limit_select_ops,
	.policy		= nft_limit_policy,
	.maxattr	= NFTA_LIMIT_MAX,
	.flags		= NFT_EXPR_STATEFUL,
	.owner		= THIS_MODULE,
};

static void nft_limit_obj_pkts_eval(struct nft_object *obj,
				    struct nft_regs *regs,
				    const struct nft_pktinfo *pkt)
{
	struct nft_limit_pkts *priv = nft_obj_data(obj);

	if (nft_limit_eval(&priv->limit, priv->cost))
		regs->verdict.code = NFT_BREAK;
}

static int nft_limit_obj_pkts_init(const struct nft_ctx *ctx,
				   const struct nlattr * const tb[],
				   struct nft_object *obj)
{
	struct nft_limit_pkts *priv = nft_obj_data(obj);
	int err;

	err = nft_limit_init(&priv->limit, tb, true);
	if (err < 0)
		return err;

	priv->cost = div64_u64(priv->limit.nsecs, priv->limit.rate);
	return 0;
}

static int nft_limit_obj_pkts_dump(struct sk_buff *skb,
				   struct nft_object *obj,
				   bool reset)
{
	const struct nft_limit_pkts *priv = nft_obj_data(obj);

	return nft_limit_dump(skb, &priv->limit, NFT_LIMIT_PKTS);
}

static struct nft_object_type nft_limit_obj_type;
static const struct nft_object_ops nft_limit_obj_pkts_ops = {
	.type		= &nft_limit_obj_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_limit_pkts)),
	.init		= nft_limit_obj_pkts_init,
	.eval		= nft_limit_obj_pkts_eval,
	.dump		= nft_limit_obj_pkts_dump,
};

static void nft_limit_obj_bytes_eval(struct nft_object *obj,
				     struct nft_regs *regs,
				     const struct nft_pktinfo *pkt)
{
	struct nft_limit *priv = nft_obj_data(obj);
	u64 cost = div64_u64(priv->nsecs * pkt->skb->len, priv->rate);

	if (nft_limit_eval(priv, cost))
		regs->verdict.code = NFT_BREAK;
}

static int nft_limit_obj_bytes_init(const struct nft_ctx *ctx,
				    const struct nlattr * const tb[],
				    struct nft_object *obj)
{
	struct nft_limit *priv = nft_obj_data(obj);

	return nft_limit_init(priv, tb, false);
}

static int nft_limit_obj_bytes_dump(struct sk_buff *skb,
				    struct nft_object *obj,
				    bool reset)
{
	const struct nft_limit *priv = nft_obj_data(obj);

	return nft_limit_dump(skb, priv, NFT_LIMIT_PKT_BYTES);
}

static struct nft_object_type nft_limit_obj_type;
static const struct nft_object_ops nft_limit_obj_bytes_ops = {
	.type		= &nft_limit_obj_type,
	.size		= sizeof(struct nft_limit),
	.init		= nft_limit_obj_bytes_init,
	.eval		= nft_limit_obj_bytes_eval,
	.dump		= nft_limit_obj_bytes_dump,
};

static const struct nft_object_ops *
nft_limit_obj_select_ops(const struct nft_ctx *ctx,
			 const struct nlattr * const tb[])
{
	if (!tb[NFTA_LIMIT_TYPE])
		return &nft_limit_obj_pkts_ops;

	switch (ntohl(nla_get_be32(tb[NFTA_LIMIT_TYPE]))) {
	case NFT_LIMIT_PKTS:
		return &nft_limit_obj_pkts_ops;
	case NFT_LIMIT_PKT_BYTES:
		return &nft_limit_obj_bytes_ops;
	}
	return ERR_PTR(-EOPNOTSUPP);
}

static struct nft_object_type nft_limit_obj_type __read_mostly = {
	.select_ops	= nft_limit_obj_select_ops,
	.type		= NFT_OBJECT_LIMIT,
	.maxattr	= NFTA_LIMIT_MAX,
	.policy		= nft_limit_policy,
	.owner		= THIS_MODULE,
};

static int __init nft_limit_module_init(void)
{
	int err;

	err = nft_register_obj(&nft_limit_obj_type);
	if (err < 0)
		return err;

	err = nft_register_expr(&nft_limit_type);
	if (err < 0)
		goto err1;

	return 0;
err1:
	nft_unregister_obj(&nft_limit_obj_type);
	return err;
}

static void __exit nft_limit_module_exit(void)
{
	nft_unregister_expr(&nft_limit_type);
	nft_unregister_obj(&nft_limit_obj_type);
}

module_init(nft_limit_module_init);
module_exit(nft_limit_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_ALIAS_NFT_EXPR("limit");
MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_LIMIT);