![Andrew Morton](/assets/img/avatar_default.png)
Every netfilter module uses `init' for its module_init() function and `fini' or `cleanup' for its module_exit() function. Problem is, this creates uninformative initcall_debug output and makes ctags rather useless. So go through and rename them all to $(filename)_init and $(filename)_fini. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
137 lines
3 KiB
C
137 lines
3 KiB
C
/* Kernel module to match TCP MSS values. */
|
|
|
|
/* Copyright (C) 2000 Marc Boucher <marc@mbsi.ca>
|
|
* Portions (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 <net/tcp.h>
|
|
|
|
#include <linux/netfilter/xt_tcpmss.h>
|
|
#include <linux/netfilter/x_tables.h>
|
|
|
|
#include <linux/netfilter_ipv4/ip_tables.h>
|
|
#include <linux/netfilter_ipv6/ip6_tables.h>
|
|
|
|
#define TH_SYN 0x02
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
|
|
MODULE_DESCRIPTION("iptables TCP MSS match module");
|
|
MODULE_ALIAS("ipt_tcpmss");
|
|
|
|
/* Returns 1 if the mss option is set and matched by the range, 0 otherwise */
|
|
static inline int
|
|
mssoption_match(u_int16_t min, u_int16_t max,
|
|
const struct sk_buff *skb,
|
|
unsigned int protoff,
|
|
int invert,
|
|
int *hotdrop)
|
|
{
|
|
struct tcphdr _tcph, *th;
|
|
/* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
|
|
u8 _opt[15 * 4 - sizeof(_tcph)], *op;
|
|
unsigned int i, optlen;
|
|
|
|
/* If we don't have the whole header, drop packet. */
|
|
th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
|
|
if (th == NULL)
|
|
goto dropit;
|
|
|
|
/* Malformed. */
|
|
if (th->doff*4 < sizeof(*th))
|
|
goto dropit;
|
|
|
|
optlen = th->doff*4 - sizeof(*th);
|
|
if (!optlen)
|
|
goto out;
|
|
|
|
/* Truncated options. */
|
|
op = skb_header_pointer(skb, protoff + sizeof(*th), optlen, _opt);
|
|
if (op == NULL)
|
|
goto dropit;
|
|
|
|
for (i = 0; i < optlen; ) {
|
|
if (op[i] == TCPOPT_MSS
|
|
&& (optlen - i) >= TCPOLEN_MSS
|
|
&& op[i+1] == TCPOLEN_MSS) {
|
|
u_int16_t mssval;
|
|
|
|
mssval = (op[i+2] << 8) | op[i+3];
|
|
|
|
return (mssval >= min && mssval <= max) ^ invert;
|
|
}
|
|
if (op[i] < 2) i++;
|
|
else i += op[i+1]?:1;
|
|
}
|
|
out:
|
|
return invert;
|
|
|
|
dropit:
|
|
*hotdrop = 1;
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
match(const struct sk_buff *skb,
|
|
const struct net_device *in,
|
|
const struct net_device *out,
|
|
const struct xt_match *match,
|
|
const void *matchinfo,
|
|
int offset,
|
|
unsigned int protoff,
|
|
int *hotdrop)
|
|
{
|
|
const struct xt_tcpmss_match_info *info = matchinfo;
|
|
|
|
return mssoption_match(info->mss_min, info->mss_max, skb, protoff,
|
|
info->invert, hotdrop);
|
|
}
|
|
|
|
static struct xt_match tcpmss_match = {
|
|
.name = "tcpmss",
|
|
.match = match,
|
|
.matchsize = sizeof(struct xt_tcpmss_match_info),
|
|
.proto = IPPROTO_TCP,
|
|
.family = AF_INET,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
static struct xt_match tcpmss6_match = {
|
|
.name = "tcpmss",
|
|
.match = match,
|
|
.matchsize = sizeof(struct xt_tcpmss_match_info),
|
|
.proto = IPPROTO_TCP,
|
|
.family = AF_INET6,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
|
|
static int __init xt_tcpmss_init(void)
|
|
{
|
|
int ret;
|
|
ret = xt_register_match(&tcpmss_match);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = xt_register_match(&tcpmss6_match);
|
|
if (ret)
|
|
xt_unregister_match(&tcpmss_match);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __exit xt_tcpmss_fini(void)
|
|
{
|
|
xt_unregister_match(&tcpmss6_match);
|
|
xt_unregister_match(&tcpmss_match);
|
|
}
|
|
|
|
module_init(xt_tcpmss_init);
|
|
module_exit(xt_tcpmss_fini);
|