222 lines
5.1 KiB
C
222 lines
5.1 KiB
C
/*
|
|
* iptables module for DCCP protocol header matching
|
|
*
|
|
* (C) 2005 by Harald Welte <laforge@netfilter.org>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/spinlock.h>
|
|
#include <net/ip.h>
|
|
#include <linux/dccp.h>
|
|
|
|
#include <linux/netfilter/x_tables.h>
|
|
#include <linux/netfilter/xt_dccp.h>
|
|
|
|
#include <linux/netfilter_ipv4/ip_tables.h>
|
|
#include <linux/netfilter_ipv6/ip6_tables.h>
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
|
|
MODULE_DESCRIPTION("Match for DCCP protocol packets");
|
|
MODULE_ALIAS("ipt_dccp");
|
|
|
|
#define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
|
|
|| (!!((invflag) & (option)) ^ (cond)))
|
|
|
|
static unsigned char *dccp_optbuf;
|
|
static DEFINE_SPINLOCK(dccp_buflock);
|
|
|
|
static inline int
|
|
dccp_find_option(u_int8_t option,
|
|
const struct sk_buff *skb,
|
|
unsigned int protoff,
|
|
const struct dccp_hdr *dh,
|
|
int *hotdrop)
|
|
{
|
|
/* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
|
|
unsigned char *op;
|
|
unsigned int optoff = __dccp_hdr_len(dh);
|
|
unsigned int optlen = dh->dccph_doff*4 - __dccp_hdr_len(dh);
|
|
unsigned int i;
|
|
|
|
if (dh->dccph_doff * 4 < __dccp_hdr_len(dh)) {
|
|
*hotdrop = 1;
|
|
return 0;
|
|
}
|
|
|
|
if (!optlen)
|
|
return 0;
|
|
|
|
spin_lock_bh(&dccp_buflock);
|
|
op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf);
|
|
if (op == NULL) {
|
|
/* If we don't have the whole header, drop packet. */
|
|
spin_unlock_bh(&dccp_buflock);
|
|
*hotdrop = 1;
|
|
return 0;
|
|
}
|
|
|
|
for (i = 0; i < optlen; ) {
|
|
if (op[i] == option) {
|
|
spin_unlock_bh(&dccp_buflock);
|
|
return 1;
|
|
}
|
|
|
|
if (op[i] < 2)
|
|
i++;
|
|
else
|
|
i += op[i+1]?:1;
|
|
}
|
|
|
|
spin_unlock_bh(&dccp_buflock);
|
|
return 0;
|
|
}
|
|
|
|
|
|
static inline int
|
|
match_types(const struct dccp_hdr *dh, u_int16_t typemask)
|
|
{
|
|
return (typemask & (1 << dh->dccph_type));
|
|
}
|
|
|
|
static inline int
|
|
match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff,
|
|
const struct dccp_hdr *dh, int *hotdrop)
|
|
{
|
|
return dccp_find_option(option, skb, protoff, dh, hotdrop);
|
|
}
|
|
|
|
static int
|
|
match(const struct sk_buff *skb,
|
|
const struct net_device *in,
|
|
const struct net_device *out,
|
|
const void *matchinfo,
|
|
int offset,
|
|
unsigned int protoff,
|
|
int *hotdrop)
|
|
{
|
|
const struct xt_dccp_info *info =
|
|
(const struct xt_dccp_info *)matchinfo;
|
|
struct dccp_hdr _dh, *dh;
|
|
|
|
if (offset)
|
|
return 0;
|
|
|
|
dh = skb_header_pointer(skb, protoff, sizeof(_dh), &_dh);
|
|
if (dh == NULL) {
|
|
*hotdrop = 1;
|
|
return 0;
|
|
}
|
|
|
|
return DCCHECK(((ntohs(dh->dccph_sport) >= info->spts[0])
|
|
&& (ntohs(dh->dccph_sport) <= info->spts[1])),
|
|
XT_DCCP_SRC_PORTS, info->flags, info->invflags)
|
|
&& DCCHECK(((ntohs(dh->dccph_dport) >= info->dpts[0])
|
|
&& (ntohs(dh->dccph_dport) <= info->dpts[1])),
|
|
XT_DCCP_DEST_PORTS, info->flags, info->invflags)
|
|
&& DCCHECK(match_types(dh, info->typemask),
|
|
XT_DCCP_TYPE, info->flags, info->invflags)
|
|
&& DCCHECK(match_option(info->option, skb, protoff, dh,
|
|
hotdrop),
|
|
XT_DCCP_OPTION, info->flags, info->invflags);
|
|
}
|
|
|
|
static int
|
|
checkentry(const char *tablename,
|
|
const void *inf,
|
|
void *matchinfo,
|
|
unsigned int matchsize,
|
|
unsigned int hook_mask)
|
|
{
|
|
const struct ipt_ip *ip = inf;
|
|
const struct xt_dccp_info *info;
|
|
|
|
info = (const struct xt_dccp_info *)matchinfo;
|
|
|
|
return ip->proto == IPPROTO_DCCP
|
|
&& !(ip->invflags & XT_INV_PROTO)
|
|
&& matchsize == XT_ALIGN(sizeof(struct xt_dccp_info))
|
|
&& !(info->flags & ~XT_DCCP_VALID_FLAGS)
|
|
&& !(info->invflags & ~XT_DCCP_VALID_FLAGS)
|
|
&& !(info->invflags & ~info->flags);
|
|
}
|
|
|
|
static int
|
|
checkentry6(const char *tablename,
|
|
const void *inf,
|
|
void *matchinfo,
|
|
unsigned int matchsize,
|
|
unsigned int hook_mask)
|
|
{
|
|
const struct ip6t_ip6 *ip = inf;
|
|
const struct xt_dccp_info *info;
|
|
|
|
info = (const struct xt_dccp_info *)matchinfo;
|
|
|
|
return ip->proto == IPPROTO_DCCP
|
|
&& !(ip->invflags & XT_INV_PROTO)
|
|
&& matchsize == XT_ALIGN(sizeof(struct xt_dccp_info))
|
|
&& !(info->flags & ~XT_DCCP_VALID_FLAGS)
|
|
&& !(info->invflags & ~XT_DCCP_VALID_FLAGS)
|
|
&& !(info->invflags & ~info->flags);
|
|
}
|
|
|
|
|
|
static struct xt_match dccp_match =
|
|
{
|
|
.name = "dccp",
|
|
.match = &match,
|
|
.checkentry = &checkentry,
|
|
.me = THIS_MODULE,
|
|
};
|
|
static struct xt_match dccp6_match =
|
|
{
|
|
.name = "dccp",
|
|
.match = &match,
|
|
.checkentry = &checkentry6,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
|
|
static int __init init(void)
|
|
{
|
|
int ret;
|
|
|
|
/* doff is 8 bits, so the maximum option size is (4*256). Don't put
|
|
* this in BSS since DaveM is worried about locked TLB's for kernel
|
|
* BSS. */
|
|
dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL);
|
|
if (!dccp_optbuf)
|
|
return -ENOMEM;
|
|
ret = xt_register_match(AF_INET, &dccp_match);
|
|
if (ret)
|
|
goto out_kfree;
|
|
ret = xt_register_match(AF_INET6, &dccp6_match);
|
|
if (ret)
|
|
goto out_unreg;
|
|
|
|
return ret;
|
|
|
|
out_unreg:
|
|
xt_unregister_match(AF_INET, &dccp_match);
|
|
out_kfree:
|
|
kfree(dccp_optbuf);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __exit fini(void)
|
|
{
|
|
xt_unregister_match(AF_INET6, &dccp6_match);
|
|
xt_unregister_match(AF_INET, &dccp_match);
|
|
kfree(dccp_optbuf);
|
|
}
|
|
|
|
module_init(init);
|
|
module_exit(fini);
|