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/* Kernel module to match one of a list of TCP/UDP ports: ports are in
the same place so we can treat them as equal. */
#include <linux/module.h>
#include <linux/types.h>
#include <linux/udp.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/netfilter_ipv6/ip6t_multiport.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#if 0
#define duprintf(format, args...) printk(format , ## args)
#else
#define duprintf(format, args...)
#endif
/* Returns 1 if the port is matched by the test, 0 otherwise. */
static inline int
ports_match(const u_int16_t *portlist, enum ip6t_multiport_flags flags,
u_int8_t count, u_int16_t src, u_int16_t dst)
{
unsigned int i;
for (i=0; i<count; i++) {
if (flags != IP6T_MULTIPORT_DESTINATION
&& portlist[i] == src)
return 1;
if (flags != IP6T_MULTIPORT_SOURCE
&& portlist[i] == dst)
return 1;
}
return 0;
}
static int
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const void *matchinfo,
int offset,
const void *hdr,
u_int16_t datalen,
int *hotdrop)
{
const struct udphdr *udp = hdr;
const struct ip6t_multiport *multiinfo = matchinfo;
/* Must be big enough to read ports. */
if (offset == 0 && datalen < sizeof(struct udphdr)) {
/* We've been asked to examine this packet, and we
can't. Hence, no choice but to drop. */
duprintf("ipt_multiport:"
" Dropping evil offset=0 tinygram.\n");
*hotdrop = 1;
return 0;
}
/* Must not be a fragment. */
return !offset
&& ports_match(multiinfo->ports,
multiinfo->flags, multiinfo->count,
ntohs(udp->source), ntohs(udp->dest));
}
/* Called when user tries to insert an entry of this type. */
static int
checkentry(const char *tablename,
const struct ip6t_ip6 *ip,
void *matchinfo,
unsigned int matchsize,
unsigned int hook_mask)
{
const struct ip6t_multiport *multiinfo = matchinfo;
/* Must specify proto == TCP/UDP, no unknown flags or bad count */
return (ip->proto == IPPROTO_TCP || ip->proto == IPPROTO_UDP)
&& !(ip->flags & IP6T_INV_PROTO)
&& matchsize == IP6T_ALIGN(sizeof(struct ip6t_multiport))
&& (multiinfo->flags == IP6T_MULTIPORT_SOURCE
|| multiinfo->flags == IP6T_MULTIPORT_DESTINATION
|| multiinfo->flags == IP6T_MULTIPORT_EITHER)
&& multiinfo->count <= IP6T_MULTI_PORTS;
}
static struct ip6t_match multiport_match
= { { NULL, NULL }, "multiport", &match, &checkentry, NULL, THIS_MODULE };
static int __init init(void)
{
return ip6t_register_match(&multiport_match);
}
static void __exit fini(void)
{
ip6t_unregister_match(&multiport_match);
}
module_init(init);
module_exit(fini);
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