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
|
/* Shared library add-on to iptables to add connection limit support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <getopt.h>
#include <iptables.h>
#include "../include/linux/netfilter/xt_connlimit.h"
static void connlimit_help(void)
{
printf(
"connlimit v%s options:\n"
"[!] --connlimit-above n match if the number of existing "
" connections is (not) above n\n"
" --connlimit-mask n group hosts using mask\n"
"\n", IPTABLES_VERSION);
}
static const struct option connlimit_opts[] = {
{"connlimit-above", 1, NULL, 'A'},
{"connlimit-mask", 1, NULL, 'M'},
{NULL},
};
static void connlimit_init(struct xt_entry_match *match)
{
struct xt_connlimit_info *info = (void *)match->data;
info->v4_mask = 0xFFFFFFFFUL;
}
static void prefix_to_netmask(u_int32_t *mask, unsigned int prefix_len)
{
if (prefix_len == 0) {
mask[0] = mask[1] = mask[2] = mask[3] = 0;
} else if (prefix_len <= 32) {
mask[0] <<= 32 - prefix_len;
mask[1] = mask[2] = mask[3] = 0;
} else if (prefix_len <= 64) {
mask[1] <<= 32 - (prefix_len - 32);
mask[2] = mask[3] = 0;
} else if (prefix_len <= 96) {
mask[2] <<= 32 - (prefix_len - 64);
mask[3] = 0;
} else if (prefix_len <= 128) {
mask[3] <<= 32 - (prefix_len - 96);
}
mask[0] = htonl(mask[0]);
mask[1] = htonl(mask[1]);
mask[2] = htonl(mask[2]);
mask[3] = htonl(mask[3]);
}
static int connlimit_parse(int c, char **argv, int invert, unsigned int *flags,
struct xt_connlimit_info *info, unsigned int family)
{
char *err;
int i;
switch (c) {
case 'A':
if (*flags & 0x1)
exit_error(PARAMETER_PROBLEM,
"--connlimit-above may be given only once");
*flags |= 0x1;
check_inverse(optarg, &invert, &optind, 0);
info->limit = strtoul(argv[optind-1], NULL, 0);
info->inverse = invert;
break;
case 'M':
if (*flags & 0x2)
exit_error(PARAMETER_PROBLEM,
"--connlimit-mask may be given only once");
*flags |= 0x2;
i = strtoul(argv[optind-1], &err, 0);
if (family == AF_INET6) {
if (i > 128 || *err != '\0')
exit_error(PARAMETER_PROBLEM,
"--connlimit-mask must be between "
"0 and 128");
prefix_to_netmask(info->v6_mask, i);
} else {
if (i > 32 || *err != '\0')
exit_error(PARAMETER_PROBLEM,
"--connlimit-mask must be between "
"0 and 32");
if (i == 0)
info->v4_mask = 0;
else
info->v4_mask = htonl(0xFFFFFFFF << (32 - i));
}
break;
default:
return 0;
}
return 1;
}
static int connlimit_parse4(int c, char **argv, int invert,
unsigned int *flags, const void *entry,
struct xt_entry_match **match)
{
return connlimit_parse(c, argv, invert, flags,
(void *)(*match)->data, AF_INET);
}
static int connlimit_parse6(int c, char **argv, int invert,
unsigned int *flags, const void *entry,
struct xt_entry_match **match)
{
return connlimit_parse(c, argv, invert, flags,
(void *)(*match)->data, AF_INET6);
}
static void connlimit_check(unsigned int flags)
{
if (!(flags & 0x1))
exit_error(PARAMETER_PROBLEM,
"You must specify \"--connlimit-above\"");
}
static unsigned int count_bits4(u_int32_t mask)
{
unsigned int bits = 0;
for (mask = ~ntohl(mask); mask != 0; mask >>= 1)
++bits;
return 32 - bits;
}
static unsigned int count_bits6(const u_int32_t *mask)
{
unsigned int bits = 0, i;
u_int32_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/%u %s %u ", count_bits4(info->v4_mask),
info->inverse ? "<=" : ">", 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/%u %s %u ", count_bits6(info->v6_mask),
info->inverse ? "<=" : ">", 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;
printf("%s--connlimit-above %u --connlimit-mask %u ",
info->inverse ? "! " : "", info->limit,
count_bits4(info->v4_mask));
}
static void connlimit_save6(const void *ip, const struct xt_entry_match *match)
{
const struct xt_connlimit_info *info = (const void *)match->data;
printf("%s--connlimit-above %u --connlimit-mask %u ",
info->inverse ? "! " : "", info->limit,
count_bits6(info->v6_mask));
}
static struct xtables_match connlimit_match = {
.name = "connlimit",
.family = AF_INET,
.version = IPTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_connlimit_info)),
.userspacesize = offsetof(struct xt_connlimit_info, data),
.help = connlimit_help,
.init = connlimit_init,
.parse = connlimit_parse4,
.final_check = connlimit_check,
.print = connlimit_print4,
.save = connlimit_save4,
.extra_opts = connlimit_opts,
};
static struct xtables_match connlimit_match6 = {
.name = "connlimit",
.family = AF_INET6,
.version = IPTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_connlimit_info)),
.userspacesize = offsetof(struct xt_connlimit_info, data),
.help = connlimit_help,
.init = connlimit_init,
.parse = connlimit_parse6,
.final_check = connlimit_check,
.print = connlimit_print6,
.save = connlimit_save6,
.extra_opts = connlimit_opts,
};
void _init(void)
{
xtables_register_match(&connlimit_match);
xtables_register_match(&connlimit_match6);
}
|
