summaryrefslogtreecommitdiffstats
path: root/extensions/libipt_hashlimit.c
blob: f59b66724b46baa7c856bc2196bf442634b93523 (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
/* iptables match extension for limiting packets per destination
 *
 * (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
 *
 * Development of this code was funded by Astaro AG, http://www.astaro.com/
 *
 * Based on ipt_limit.c by
 * Jérôme de Vivie   <devivie@info.enserb.u-bordeaux.fr>
 * Hervé Eychenne    <rv@wallfire.org>
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <stddef.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_hashlimit.h>

#define IPT_HASHLIMIT_BURST	5

/* miliseconds */
#define IPT_HASHLIMIT_GCINTERVAL	1000
#define IPT_HASHLIMIT_EXPIRE	10000

/* Function which prints out usage message. */
static void
help(void)
{
	printf(
"hashlimit v%s options:\n"
"--hashlimit <avg>		max average match rate\n"
"                                [Packets per second unless followed by \n"
"                                /sec /minute /hour /day postfixes]\n"
"--hashlimit-mode <mode>		mode is a comma-separated list of\n"
"					dstip,srcip,dstport,srcport\n"
"--hashlimit-name <name>		name for /proc/net/ipt_hashlimit/\n"
"[--hashlimit-burst <num>]	number to match in a burst, default %u\n"
"[--hashlimit-htable-size <num>]	number of hashtable buckets\n"
"[--hashlimit-htable-max <num>]	number of hashtable entries\n"
"[--hashlimit-htable-gcinterval]	interval between garbage collection runs\n"
"[--hashlimit-htable-expire]	after which time are idle entries expired?\n"
"\n", IPTABLES_VERSION, IPT_HASHLIMIT_BURST);
}

static struct option opts[] = {
	{ "hashlimit", 1, 0, '%' },
	{ "hashlimit-burst", 1, 0, '$' },
	{ "hashlimit-htable-size", 1, 0, '&' },
	{ "hashlimit-htable-max", 1, 0, '*' },
	{ "hashlimit-htable-gcinterval", 1, 0, '(' },
	{ "hashlimit-htable-expire", 1, 0, ')' },
	{ "hashlimit-mode", 1, 0, '_' },
	{ "hashlimit-name", 1, 0, '"' },
	{ 0 }
};

static
int parse_rate(const char *rate, u_int32_t *val)
{
	const char *delim;
	u_int32_t r;
	u_int32_t mult = 1;  /* Seconds by default. */

	delim = strchr(rate, '/');
	if (delim) {
		if (strlen(delim+1) == 0)
			return 0;

		if (strncasecmp(delim+1, "second", strlen(delim+1)) == 0)
			mult = 1;
		else if (strncasecmp(delim+1, "minute", strlen(delim+1)) == 0)
			mult = 60;
		else if (strncasecmp(delim+1, "hour", strlen(delim+1)) == 0)
			mult = 60*60;
		else if (strncasecmp(delim+1, "day", strlen(delim+1)) == 0)
			mult = 24*60*60;
		else
			return 0;
	}
	r = atoi(rate);
	if (!r)
		return 0;

	/* This would get mapped to infinite (1/day is minimum they
           can specify, so we're ok at that end). */
	if (r / mult > IPT_HASHLIMIT_SCALE)
		exit_error(PARAMETER_PROBLEM, "Rate too fast `%s'\n", rate);

	*val = IPT_HASHLIMIT_SCALE * mult / r;
	return 1;
}

/* Initialize the match. */
static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
	struct ipt_hashlimit_info *r = (struct ipt_hashlimit_info *)m->data;

	r->cfg.burst = IPT_HASHLIMIT_BURST;
	r->cfg.gc_interval = IPT_HASHLIMIT_GCINTERVAL;
	r->cfg.expire = IPT_HASHLIMIT_EXPIRE;

	/* Can't cache this */
	*nfcache |= NFC_UNKNOWN;
}


/* Parse a 'mode' parameter into the required bitmask */
static int parse_mode(struct ipt_hashlimit_info *r, char *optarg)
{
	char *tok;
	char *arg = strdup(optarg);

	if (!arg)
		return -1;

	r->cfg.mode = 0;

	for (tok = strtok(arg, ",|");
	     tok;
	     tok = strtok(NULL, ",|")) {
		if (!strcmp(tok, "dstip"))
			r->cfg.mode |= IPT_HASHLIMIT_HASH_DIP;
		else if (!strcmp(tok, "srcip"))
			r->cfg.mode |= IPT_HASHLIMIT_HASH_SIP;
		else if (!strcmp(tok, "srcport"))
			r->cfg.mode |= IPT_HASHLIMIT_HASH_SPT;
		else if (!strcmp(tok, "dstport"))
			r->cfg.mode |= IPT_HASHLIMIT_HASH_DPT;
		else {
			free(arg);
			return -1;
		}
	}
	free(arg);
	return 0;
}

#define PARAM_LIMIT		0x00000001
#define PARAM_BURST		0x00000002
#define PARAM_MODE		0x00000004
#define PARAM_NAME		0x00000008
#define PARAM_SIZE		0x00000010
#define PARAM_MAX		0x00000020
#define PARAM_GCINTERVAL	0x00000040
#define PARAM_EXPIRE		0x00000080

/* Function which parses command options; returns true if it
   ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
      const struct ipt_entry *entry,
      unsigned int *nfcache,
      struct ipt_entry_match **match)
{
	struct ipt_hashlimit_info *r = 
			(struct ipt_hashlimit_info *)(*match)->data;
	unsigned int num;

	switch(c) {
	case '%':
		if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
		if (!parse_rate(optarg, &r->cfg.avg))
			exit_error(PARAMETER_PROBLEM,
				   "bad rate `%s'", optarg);
		*flags |= PARAM_LIMIT;
		break;

	case '$':
		if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
		if (string_to_number(optarg, 0, 10000, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				   "bad --hashlimit-burst `%s'", optarg);
		r->cfg.burst = num;
		*flags |= PARAM_BURST;
		break;
	case '&':
		if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				"bad --hashlimit-htable-size: `%s'", optarg);
		r->cfg.size = num;
		*flags |= PARAM_SIZE;
		break;
	case '*':
		if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				"bad --hashlimit-htable-max: `%s'", optarg);
		r->cfg.max = num;
		*flags |= PARAM_MAX;
		break;
	case '(':
		if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				"bad --hashlimit-htable-gcinterval: `%s'", 
				optarg);
		/* FIXME: not HZ dependent!! */
		r->cfg.gc_interval = num;
		*flags |= PARAM_GCINTERVAL;
		break;
	case ')':
		if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				"bad --hashlimit-htable-expire: `%s'", optarg);
		/* FIXME: not HZ dependent */
		r->cfg.expire = num;
		*flags |= PARAM_EXPIRE;
		break;
	case '_':
		if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
		if (parse_mode(r, optarg) < 0)
			exit_error(PARAMETER_PROBLEM, 
				   "bad --hashlimit-mode: `%s'\n", optarg);
		*flags |= PARAM_MODE;
		break;
	case '"':
		if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
		if (strlen(optarg) == 0)
			exit_error(PARAMETER_PROBLEM, "Zero-length name?");
		strncpy(r->name, optarg, sizeof(r->name));
		*flags |= PARAM_NAME;
		break;
	default:
		return 0;
	}

	if (invert)
		exit_error(PARAMETER_PROBLEM,
			   "hashlimit does not support invert");

	return 1;
}

/* Final check; nothing. */
static void final_check(unsigned int flags)
{
	if (!(flags & PARAM_LIMIT))
		exit_error(PARAMETER_PROBLEM,
				"You have to specify --hashlimit");
	if (!(flags & PARAM_MODE))
		exit_error(PARAMETER_PROBLEM,
				"You have to specify --hashlimit-mode");
	if (!(flags & PARAM_NAME))
		exit_error(PARAMETER_PROBLEM,
				"You have to specify --hashlimit-name");
}

static struct rates
{
	const char *name;
	u_int32_t mult;
} rates[] = { { "day", IPT_HASHLIMIT_SCALE*24*60*60 },
	      { "hour", IPT_HASHLIMIT_SCALE*60*60 },
	      { "min", IPT_HASHLIMIT_SCALE*60 },
	      { "sec", IPT_HASHLIMIT_SCALE } };

static void print_rate(u_int32_t period)
{
	unsigned int i;

	for (i = 1; i < sizeof(rates)/sizeof(struct rates); i++) {
		if (period > rates[i].mult
            || rates[i].mult/period < rates[i].mult%period)
			break;
	}

	printf("%u/%s ", rates[i-1].mult / period, rates[i-1].name);
}

static void print_mode(const struct ipt_hashlimit_info *r, char separator)
{
	int prevmode = 0;

	if (r->cfg.mode & IPT_HASHLIMIT_HASH_SIP) {
		if (prevmode)
			putchar(separator);
		fputs("srcip", stdout);
		prevmode = 1;
	}
	if (r->cfg.mode & IPT_HASHLIMIT_HASH_SPT) {
		if (prevmode)
			putchar(separator);
		fputs("srcport", stdout);
		prevmode = 1;
	}
	if (r->cfg.mode & IPT_HASHLIMIT_HASH_DIP) {
		if (prevmode)
			putchar(separator);
		fputs("dstip", stdout);
		prevmode = 1;
	}
	if (r->cfg.mode & IPT_HASHLIMIT_HASH_SPT) {
		if (prevmode)
			putchar(separator);
		fputs("dstport", stdout);
	}
	putchar(' ');
}

/* Prints out the matchinfo. */
static void
print(const struct ipt_ip *ip,
      const struct ipt_entry_match *match,
      int numeric)
{
	struct ipt_hashlimit_info *r = 
		(struct ipt_hashlimit_info *)match->data;
	fputs("limit: avg ", stdout); print_rate(r->cfg.avg);
	printf("burst %u ", r->cfg.burst);
	fputs("mode ", stdout);
	print_mode(r, '-');
	if (r->cfg.size)
		printf("htable-size %u ", r->cfg.size);
	if (r->cfg.max)
		printf("htable-max %u ", r->cfg.max);
	if (r->cfg.gc_interval != IPT_HASHLIMIT_GCINTERVAL)
		printf("htable-gcinterval %u ", r->cfg.gc_interval);
	if (r->cfg.expire != IPT_HASHLIMIT_EXPIRE)
		printf("htable-expire %u ", r->cfg.expire);
}

/* FIXME: Make minimalist: only print rate if not default --RR */
static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
{
	struct ipt_hashlimit_info *r = 
		(struct ipt_hashlimit_info *)match->data;

	fputs("--hashlimit ", stdout); print_rate(r->cfg.avg);
	if (r->cfg.burst != IPT_HASHLIMIT_BURST)
		printf("--hashlimit-burst %u ", r->cfg.burst);

	fputs("--mode ", stdout);
	print_mode(r, ',');

	if (r->cfg.size)
		printf("--hashlimit-htable-size %u ", r->cfg.size);
	if (r->cfg.max)
		printf("--hashlimit-htable-max %u ", r->cfg.max);
	if (r->cfg.gc_interval != IPT_HASHLIMIT_GCINTERVAL)
		printf("--hashlimit-htable-gcinterval %u", r->cfg.gc_interval);
	if (r->cfg.expire != IPT_HASHLIMIT_EXPIRE)
		printf("--hashlimit-htable-expire %u ", r->cfg.expire);
}

static struct iptables_match hashlimit = { NULL,
	.name		= "hashlimit",
	.version	= IPTABLES_VERSION,
	.size		= IPT_ALIGN(sizeof(struct ipt_hashlimit_info)),
	.userspacesize	= IPT_ALIGN(sizeof(struct ipt_hashlimit_info)),
    	//offsetof(struct ipt_hashlimit_info, prev),
	.help		= &help,
	.init		= &init,
	.parse		= &parse,
	.final_check	= &final_check,
	.print		= &print,
	.save		= &save,
	.extra_opts	= opts
};

void _init(void)
{
	register_match(&hashlimit);
}