summaryrefslogtreecommitdiffstats
path: root/extensions/libxt_connlimit.c
blob: 118faea560f73cfefc6e60db2b65634889d68e48 (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
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <xtables.h>
#include <arpa/inet.h>

#include <linux/netfilter/xt_connlimit.h>

enum {
	O_UPTO = 0,
	O_ABOVE,
	O_MASK,
	O_SADDR,
	O_DADDR,
	F_UPTO  = 1 << O_UPTO,
	F_ABOVE = 1 << O_ABOVE,
	F_MASK  = 1 << O_MASK,
	F_SADDR = 1 << O_SADDR,
	F_DADDR = 1 << O_DADDR,
};

static void connlimit_help(void)
{
	printf(
"connlimit match options:\n"
"  --connlimit-upto n     match if the number of existing connections is 0..n\n"
"  --connlimit-above n    match if the number of existing connections is >n\n"
"  --connlimit-mask n     group hosts using prefix length (default: max len)\n"
"  --connlimit-saddr      select source address for grouping\n"
"  --connlimit-daddr      select destination addresses for grouping\n");
}

#define s struct xt_connlimit_info
static const struct xt_option_entry connlimit_opts[] = {
	{.name = "connlimit-upto", .id = O_UPTO, .excl = F_ABOVE,
	 .type = XTTYPE_UINT32, .flags = XTOPT_INVERT | XTOPT_PUT,
	 XTOPT_POINTER(s, limit)},
	{.name = "connlimit-above", .id = O_ABOVE, .excl = F_UPTO,
	 .type = XTTYPE_UINT32, .flags = XTOPT_INVERT | XTOPT_PUT,
	 XTOPT_POINTER(s, limit)},
	{.name = "connlimit-mask", .id = O_MASK, .type = XTTYPE_PLENMASK,
	 .flags = XTOPT_PUT, XTOPT_POINTER(s, mask)},
	{.name = "connlimit-saddr", .id = O_SADDR, .excl = F_DADDR,
	 .type = XTTYPE_NONE},
	{.name = "connlimit-daddr", .id = O_DADDR, .excl = F_SADDR,
	 .type = XTTYPE_NONE},
	XTOPT_TABLEEND,
};
#undef s

static void connlimit_init(struct xt_entry_match *match)
{
	struct xt_connlimit_info *info = (void *)match->data;

	/* This will also initialize the v4 mask correctly */
	memset(info->v6_mask, 0xFF, sizeof(info->v6_mask));
}

static void connlimit_parse(struct xt_option_call *cb, uint8_t family)
{
	struct xt_connlimit_info *info = cb->data;
	const unsigned int revision = (*cb->match)->u.user.revision;

	xtables_option_parse(cb);
	switch (cb->entry->id) {
	case O_ABOVE:
		if (cb->invert)
			info->flags |= XT_CONNLIMIT_INVERT;
		break;
	case O_UPTO:
		if (!cb->invert)
			info->flags |= XT_CONNLIMIT_INVERT;
		break;
	case O_SADDR:
		if (revision < 1)
			xtables_error(PARAMETER_PROBLEM,
				"xt_connlimit.0 does not support "
				"--connlimit-daddr");
		info->flags &= ~XT_CONNLIMIT_DADDR;
		break;
	case O_DADDR:
		if (revision < 1)
			xtables_error(PARAMETER_PROBLEM,
				"xt_connlimit.0 does not support "
				"--connlimit-daddr");
		info->flags |= XT_CONNLIMIT_DADDR;
		break;
	}
}

static void connlimit_parse4(struct xt_option_call *cb)
{
	return connlimit_parse(cb, NFPROTO_IPV4);
}

static void connlimit_parse6(struct xt_option_call *cb)
{
	return connlimit_parse(cb, NFPROTO_IPV6);
}

static void connlimit_check(struct xt_fcheck_call *cb)
{
	if ((cb->xflags & (F_UPTO | F_ABOVE)) == 0)
		xtables_error(PARAMETER_PROBLEM,
			"You must specify \"--connlimit-above\" or "
			"\"--connlimit-upto\".");
}

static unsigned int count_bits4(uint32_t mask)
{
	unsigned int bits = 0;

	for (mask = ~ntohl(mask); mask != 0; mask >>= 1)
		++bits;

	return 32 - bits;
}

static unsigned int count_bits6(const uint32_t *mask)
{
	unsigned int bits = 0, i;
	uint32_t tmp[4];

	for (i = 0; i < 4; ++i)
		for (tmp[i] = ~ntohl(mask[i]); tmp[i] != 0; tmp[i] >>= 1)
			++bits;
	return 128 - bits;
}

static void connlimit_print4(const void *ip,
                             const struct xt_entry_match *match, int numeric)
{
	const struct xt_connlimit_info *info = (const void *)match->data;

	printf(" #conn %s/%u %s %u",
	       (info->flags & XT_CONNLIMIT_DADDR) ? "dst" : "src",
	       count_bits4(info->v4_mask),
	       (info->flags & XT_CONNLIMIT_INVERT) ? "<=" : ">", info->limit);
}

static void connlimit_print6(const void *ip,
                             const struct xt_entry_match *match, int numeric)
{
	const struct xt_connlimit_info *info = (const void *)match->data;

	printf(" #conn %s/%u %s %u",
	       (info->flags & XT_CONNLIMIT_DADDR) ? "dst" : "src",
	       count_bits6(info->v6_mask),
	       (info->flags & XT_CONNLIMIT_INVERT) ? "<=" : ">", info->limit);
}

static void connlimit_save4(const void *ip, const struct xt_entry_match *match)
{
	const struct xt_connlimit_info *info = (const void *)match->data;
	const int revision = match->u.user.revision;

	if (info->flags & XT_CONNLIMIT_INVERT)
		printf(" --connlimit-upto %u", info->limit);
	else
		printf(" --connlimit-above %u", info->limit);
	printf(" --connlimit-mask %u", count_bits4(info->v4_mask));
	if (revision >= 1) {
		if (info->flags & XT_CONNLIMIT_DADDR)
			printf(" --connlimit-daddr");
		else
			printf(" --connlimit-saddr");
	}
}

static void connlimit_save6(const void *ip, const struct xt_entry_match *match)
{
	const struct xt_connlimit_info *info = (const void *)match->data;
	const int revision = match->u.user.revision;

	if (info->flags & XT_CONNLIMIT_INVERT)
		printf(" --connlimit-upto %u", info->limit);
	else
		printf(" --connlimit-above %u", info->limit);
	printf(" --connlimit-mask %u", count_bits6(info->v6_mask));
	if (revision >= 1) {
		if (info->flags & XT_CONNLIMIT_DADDR)
			printf(" --connlimit-daddr");
		else
			printf(" --connlimit-saddr");
	}
}

static int connlimit_xlate(struct xt_xlate *xl,
			   const struct xt_xlate_mt_params *params)
{
	const struct xt_connlimit_info *info = (const void *)params->match->data;
	static uint32_t connlimit_id;
	char netmask[128] = {};
	char addr[64] = {};
	uint32_t mask;

	switch (xt_xlate_get_family(xl)) {
	case AF_INET:
		mask = count_bits4(info->v4_mask);
		if (mask != 32) {
			struct in_addr *in = (struct in_addr *)&info->v4_mask;

			inet_ntop(AF_INET, in, addr, sizeof(addr));
			snprintf(netmask, sizeof(netmask), "and %s ", addr);
		}
		break;
	case AF_INET6:
		mask = count_bits6(info->v6_mask);
		if (mask != 128) {
			struct in6_addr *in6 = (struct in6_addr *)&info->v6_mask;

			inet_ntop(AF_INET6, in6, addr, sizeof(addr));
			snprintf(netmask, sizeof(netmask), "and %s ", addr);
		}
		break;
	default:
		return 0;
	}

	xt_xlate_set_add(xl, "connlimit%u { type ipv4_addr; flags dynamic; }",
			 connlimit_id);
	xt_xlate_rule_add(xl, "add @connlimit%u { %s %s %sct count %s%u }",
			  connlimit_id++,
			  xt_xlate_get_family(xl) == AF_INET ? "ip" : "ip6",
			  info->flags & XT_CONNLIMIT_DADDR ? "daddr" : "saddr",
			  netmask,
			  info->flags & XT_CONNLIMIT_INVERT ? "" : "over ",
			  info->limit);

	return 1;
}

static struct xtables_match connlimit_mt_reg[] = {
	{
		.name          = "connlimit",
		.revision      = 0,
		.family        = NFPROTO_IPV4,
		.version       = XTABLES_VERSION,
		.size          = XT_ALIGN(sizeof(struct xt_connlimit_info)),
		.userspacesize = offsetof(struct xt_connlimit_info, data),
		.help          = connlimit_help,
		.init          = connlimit_init,
		.x6_parse      = connlimit_parse4,
		.x6_fcheck     = connlimit_check,
		.print         = connlimit_print4,
		.save          = connlimit_save4,
		.x6_options    = connlimit_opts,
	},
	{
		.name          = "connlimit",
		.revision      = 0,
		.family        = NFPROTO_IPV6,
		.version       = XTABLES_VERSION,
		.size          = XT_ALIGN(sizeof(struct xt_connlimit_info)),
		.userspacesize = offsetof(struct xt_connlimit_info, data),
		.help          = connlimit_help,
		.init          = connlimit_init,
		.x6_parse      = connlimit_parse6,
		.x6_fcheck     = connlimit_check,
		.print         = connlimit_print6,
		.save          = connlimit_save6,
		.x6_options    = connlimit_opts,
	},
	{
		.name          = "connlimit",
		.revision      = 1,
		.family        = NFPROTO_IPV4,
		.version       = XTABLES_VERSION,
		.size          = XT_ALIGN(sizeof(struct xt_connlimit_info)),
		.userspacesize = offsetof(struct xt_connlimit_info, data),
		.help          = connlimit_help,
		.init          = connlimit_init,
		.x6_parse      = connlimit_parse4,
		.x6_fcheck     = connlimit_check,
		.print         = connlimit_print4,
		.save          = connlimit_save4,
		.x6_options    = connlimit_opts,
		.xlate         = connlimit_xlate,
	},
	{
		.name          = "connlimit",
		.revision      = 1,
		.family        = NFPROTO_IPV6,
		.version       = XTABLES_VERSION,
		.size          = XT_ALIGN(sizeof(struct xt_connlimit_info)),
		.userspacesize = offsetof(struct xt_connlimit_info, data),
		.help          = connlimit_help,
		.init          = connlimit_init,
		.x6_parse      = connlimit_parse6,
		.x6_fcheck     = connlimit_check,
		.print         = connlimit_print6,
		.save          = connlimit_save6,
		.x6_options    = connlimit_opts,
		.xlate         = connlimit_xlate,
	},
};

void _init(void)
{
	xtables_register_matches(connlimit_mt_reg, ARRAY_SIZE(connlimit_mt_reg));
}