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#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));
}
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