mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-11 12:28:41 +08:00
[NETFILTER]: add IPv6-capable TCPMSS target
Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
a8d0f9526f
commit
cdd289a2f8
@ -33,6 +33,7 @@ header-y += xt_tcpmss.h
|
||||
header-y += xt_tcpudp.h
|
||||
header-y += xt_SECMARK.h
|
||||
header-y += xt_CONNSECMARK.h
|
||||
header-y += xt_TCPMSS.h
|
||||
|
||||
unifdef-y += nf_conntrack_common.h
|
||||
unifdef-y += nf_conntrack_ftp.h
|
||||
|
10
include/linux/netfilter/xt_TCPMSS.h
Normal file
10
include/linux/netfilter/xt_TCPMSS.h
Normal file
@ -0,0 +1,10 @@
|
||||
#ifndef _XT_TCPMSS_H
|
||||
#define _XT_TCPMSS_H
|
||||
|
||||
struct xt_tcpmss_info {
|
||||
u_int16_t mss;
|
||||
};
|
||||
|
||||
#define XT_TCPMSS_CLAMP_PMTU 0xffff
|
||||
|
||||
#endif /* _XT_TCPMSS_H */
|
@ -1,10 +1,9 @@
|
||||
#ifndef _IPT_TCPMSS_H
|
||||
#define _IPT_TCPMSS_H
|
||||
|
||||
struct ipt_tcpmss_info {
|
||||
u_int16_t mss;
|
||||
};
|
||||
#include <linux/netfilter/xt_TCPMSS.h>
|
||||
|
||||
#define IPT_TCPMSS_CLAMP_PMTU 0xffff
|
||||
#define ipt_tcpmss_info xt_tcpmss_info
|
||||
#define IPT_TCPMSS_CLAMP_PMTU XT_TCPMSS_CLAMP_PMTU
|
||||
|
||||
#endif /*_IPT_TCPMSS_H*/
|
||||
|
@ -361,32 +361,6 @@ config IP_NF_TARGET_ULOG
|
||||
|
||||
To compile it as a module, choose M here. If unsure, say N.
|
||||
|
||||
config IP_NF_TARGET_TCPMSS
|
||||
tristate "TCPMSS target support"
|
||||
depends on IP_NF_IPTABLES
|
||||
---help---
|
||||
This option adds a `TCPMSS' target, which allows you to alter the
|
||||
MSS value of TCP SYN packets, to control the maximum size for that
|
||||
connection (usually limiting it to your outgoing interface's MTU
|
||||
minus 40).
|
||||
|
||||
This is used to overcome criminally braindead ISPs or servers which
|
||||
block ICMP Fragmentation Needed packets. The symptoms of this
|
||||
problem are that everything works fine from your Linux
|
||||
firewall/router, but machines behind it can never exchange large
|
||||
packets:
|
||||
1) Web browsers connect, then hang with no data received.
|
||||
2) Small mail works fine, but large emails hang.
|
||||
3) ssh works fine, but scp hangs after initial handshaking.
|
||||
|
||||
Workaround: activate this option and add a rule to your firewall
|
||||
configuration like:
|
||||
|
||||
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN \
|
||||
-j TCPMSS --clamp-mss-to-pmtu
|
||||
|
||||
To compile it as a module, choose M here. If unsure, say N.
|
||||
|
||||
# NAT + specific targets: ip_conntrack
|
||||
config IP_NF_NAT
|
||||
tristate "Full NAT"
|
||||
|
@ -103,7 +103,6 @@ obj-$(CONFIG_IP_NF_TARGET_SAME) += ipt_SAME.o
|
||||
obj-$(CONFIG_IP_NF_NAT_SNMP_BASIC) += ip_nat_snmp_basic.o
|
||||
obj-$(CONFIG_IP_NF_TARGET_LOG) += ipt_LOG.o
|
||||
obj-$(CONFIG_IP_NF_TARGET_ULOG) += ipt_ULOG.o
|
||||
obj-$(CONFIG_IP_NF_TARGET_TCPMSS) += ipt_TCPMSS.o
|
||||
obj-$(CONFIG_IP_NF_TARGET_CLUSTERIP) += ipt_CLUSTERIP.o
|
||||
obj-$(CONFIG_IP_NF_TARGET_TTL) += ipt_TTL.o
|
||||
|
||||
|
@ -1,207 +0,0 @@
|
||||
/*
|
||||
* This is a module which is used for setting the MSS option in TCP packets.
|
||||
*
|
||||
* Copyright (C) 2000 Marc Boucher <marc@mbsi.ca>
|
||||
*
|
||||
* 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/ip.h>
|
||||
#include <net/tcp.h>
|
||||
|
||||
#include <linux/netfilter_ipv4/ip_tables.h>
|
||||
#include <linux/netfilter_ipv4/ipt_TCPMSS.h>
|
||||
|
||||
MODULE_LICENSE("GPL");
|
||||
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
|
||||
MODULE_DESCRIPTION("iptables TCP MSS modification module");
|
||||
|
||||
static inline unsigned int
|
||||
optlen(const u_int8_t *opt, unsigned int offset)
|
||||
{
|
||||
/* Beware zero-length options: make finite progress */
|
||||
if (opt[offset] <= TCPOPT_NOP || opt[offset+1] == 0)
|
||||
return 1;
|
||||
else
|
||||
return opt[offset+1];
|
||||
}
|
||||
|
||||
static unsigned int
|
||||
ipt_tcpmss_target(struct sk_buff **pskb,
|
||||
const struct net_device *in,
|
||||
const struct net_device *out,
|
||||
unsigned int hooknum,
|
||||
const struct xt_target *target,
|
||||
const void *targinfo)
|
||||
{
|
||||
const struct ipt_tcpmss_info *tcpmssinfo = targinfo;
|
||||
struct tcphdr *tcph;
|
||||
struct iphdr *iph;
|
||||
u_int16_t tcplen, newmss;
|
||||
__be16 newtotlen, oldval;
|
||||
unsigned int i;
|
||||
u_int8_t *opt;
|
||||
|
||||
if (!skb_make_writable(pskb, (*pskb)->len))
|
||||
return NF_DROP;
|
||||
|
||||
iph = (*pskb)->nh.iph;
|
||||
tcplen = (*pskb)->len - iph->ihl*4;
|
||||
tcph = (void *)iph + iph->ihl*4;
|
||||
|
||||
/* Since it passed flags test in tcp match, we know it is is
|
||||
not a fragment, and has data >= tcp header length. SYN
|
||||
packets should not contain data: if they did, then we risk
|
||||
running over MTU, sending Frag Needed and breaking things
|
||||
badly. --RR */
|
||||
if (tcplen != tcph->doff*4) {
|
||||
if (net_ratelimit())
|
||||
printk(KERN_ERR
|
||||
"ipt_tcpmss_target: bad length (%d bytes)\n",
|
||||
(*pskb)->len);
|
||||
return NF_DROP;
|
||||
}
|
||||
|
||||
if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU) {
|
||||
if (dst_mtu((*pskb)->dst) <= sizeof(struct iphdr) +
|
||||
sizeof(struct tcphdr)) {
|
||||
if (net_ratelimit())
|
||||
printk(KERN_ERR "ipt_tcpmss_target: "
|
||||
"unknown or invalid path-MTU (%d)\n",
|
||||
dst_mtu((*pskb)->dst));
|
||||
return NF_DROP; /* or IPT_CONTINUE ?? */
|
||||
}
|
||||
|
||||
newmss = dst_mtu((*pskb)->dst) - sizeof(struct iphdr) -
|
||||
sizeof(struct tcphdr);
|
||||
} else
|
||||
newmss = tcpmssinfo->mss;
|
||||
|
||||
opt = (u_int8_t *)tcph;
|
||||
for (i = sizeof(struct tcphdr); i < tcph->doff*4; i += optlen(opt, i)) {
|
||||
if (opt[i] == TCPOPT_MSS && tcph->doff*4 - i >= TCPOLEN_MSS &&
|
||||
opt[i+1] == TCPOLEN_MSS) {
|
||||
u_int16_t oldmss;
|
||||
|
||||
oldmss = (opt[i+2] << 8) | opt[i+3];
|
||||
|
||||
if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU &&
|
||||
oldmss <= newmss)
|
||||
return IPT_CONTINUE;
|
||||
|
||||
opt[i+2] = (newmss & 0xff00) >> 8;
|
||||
opt[i+3] = (newmss & 0x00ff);
|
||||
|
||||
nf_proto_csum_replace2(&tcph->check, *pskb,
|
||||
htons(oldmss), htons(newmss), 0);
|
||||
return IPT_CONTINUE;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* MSS Option not found ?! add it..
|
||||
*/
|
||||
if (skb_tailroom((*pskb)) < TCPOLEN_MSS) {
|
||||
struct sk_buff *newskb;
|
||||
|
||||
newskb = skb_copy_expand(*pskb, skb_headroom(*pskb),
|
||||
TCPOLEN_MSS, GFP_ATOMIC);
|
||||
if (!newskb)
|
||||
return NF_DROP;
|
||||
kfree_skb(*pskb);
|
||||
*pskb = newskb;
|
||||
iph = (*pskb)->nh.iph;
|
||||
tcph = (void *)iph + iph->ihl*4;
|
||||
}
|
||||
|
||||
skb_put((*pskb), TCPOLEN_MSS);
|
||||
|
||||
opt = (u_int8_t *)tcph + sizeof(struct tcphdr);
|
||||
memmove(opt + TCPOLEN_MSS, opt, tcplen - sizeof(struct tcphdr));
|
||||
|
||||
nf_proto_csum_replace2(&tcph->check, *pskb,
|
||||
htons(tcplen), htons(tcplen + TCPOLEN_MSS), 1);
|
||||
opt[0] = TCPOPT_MSS;
|
||||
opt[1] = TCPOLEN_MSS;
|
||||
opt[2] = (newmss & 0xff00) >> 8;
|
||||
opt[3] = (newmss & 0x00ff);
|
||||
|
||||
nf_proto_csum_replace4(&tcph->check, *pskb, 0, *((__be32 *)opt), 0);
|
||||
|
||||
oldval = ((__be16 *)tcph)[6];
|
||||
tcph->doff += TCPOLEN_MSS/4;
|
||||
nf_proto_csum_replace2(&tcph->check, *pskb,
|
||||
oldval, ((__be16 *)tcph)[6], 0);
|
||||
|
||||
newtotlen = htons(ntohs(iph->tot_len) + TCPOLEN_MSS);
|
||||
nf_csum_replace2(&iph->check, iph->tot_len, newtotlen);
|
||||
iph->tot_len = newtotlen;
|
||||
return IPT_CONTINUE;
|
||||
}
|
||||
|
||||
#define TH_SYN 0x02
|
||||
|
||||
static inline int find_syn_match(const struct ipt_entry_match *m)
|
||||
{
|
||||
const struct ipt_tcp *tcpinfo = (const struct ipt_tcp *)m->data;
|
||||
|
||||
if (strcmp(m->u.kernel.match->name, "tcp") == 0 &&
|
||||
tcpinfo->flg_cmp & TH_SYN &&
|
||||
!(tcpinfo->invflags & IPT_TCP_INV_FLAGS))
|
||||
return 1;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* Must specify -p tcp --syn/--tcp-flags SYN */
|
||||
static int
|
||||
ipt_tcpmss_checkentry(const char *tablename,
|
||||
const void *e_void,
|
||||
const struct xt_target *target,
|
||||
void *targinfo,
|
||||
unsigned int hook_mask)
|
||||
{
|
||||
const struct ipt_tcpmss_info *tcpmssinfo = targinfo;
|
||||
const struct ipt_entry *e = e_void;
|
||||
|
||||
if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU &&
|
||||
(hook_mask & ~((1 << NF_IP_FORWARD) |
|
||||
(1 << NF_IP_LOCAL_OUT) |
|
||||
(1 << NF_IP_POST_ROUTING))) != 0) {
|
||||
printk("TCPMSS: path-MTU clamping only supported in "
|
||||
"FORWARD, OUTPUT and POSTROUTING hooks\n");
|
||||
return 0;
|
||||
}
|
||||
|
||||
if (IPT_MATCH_ITERATE(e, find_syn_match))
|
||||
return 1;
|
||||
printk("TCPMSS: Only works on TCP SYN packets\n");
|
||||
return 0;
|
||||
}
|
||||
|
||||
static struct ipt_target ipt_tcpmss_reg = {
|
||||
.name = "TCPMSS",
|
||||
.target = ipt_tcpmss_target,
|
||||
.targetsize = sizeof(struct ipt_tcpmss_info),
|
||||
.proto = IPPROTO_TCP,
|
||||
.checkentry = ipt_tcpmss_checkentry,
|
||||
.me = THIS_MODULE,
|
||||
};
|
||||
|
||||
static int __init ipt_tcpmss_init(void)
|
||||
{
|
||||
return ipt_register_target(&ipt_tcpmss_reg);
|
||||
}
|
||||
|
||||
static void __exit ipt_tcpmss_fini(void)
|
||||
{
|
||||
ipt_unregister_target(&ipt_tcpmss_reg);
|
||||
}
|
||||
|
||||
module_init(ipt_tcpmss_init);
|
||||
module_exit(ipt_tcpmss_fini);
|
@ -395,6 +395,32 @@ config NETFILTER_XT_TARGET_CONNSECMARK
|
||||
|
||||
To compile it as a module, choose M here. If unsure, say N.
|
||||
|
||||
config NETFILTER_XT_TARGET_TCPMSS
|
||||
tristate '"TCPMSS" target support'
|
||||
depends on NETFILTER_XTABLES && (IPV6 || IPV6=n)
|
||||
---help---
|
||||
This option adds a `TCPMSS' target, which allows you to alter the
|
||||
MSS value of TCP SYN packets, to control the maximum size for that
|
||||
connection (usually limiting it to your outgoing interface's MTU
|
||||
minus 40).
|
||||
|
||||
This is used to overcome criminally braindead ISPs or servers which
|
||||
block ICMP Fragmentation Needed packets. The symptoms of this
|
||||
problem are that everything works fine from your Linux
|
||||
firewall/router, but machines behind it can never exchange large
|
||||
packets:
|
||||
1) Web browsers connect, then hang with no data received.
|
||||
2) Small mail works fine, but large emails hang.
|
||||
3) ssh works fine, but scp hangs after initial handshaking.
|
||||
|
||||
Workaround: activate this option and add a rule to your firewall
|
||||
configuration like:
|
||||
|
||||
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN \
|
||||
-j TCPMSS --clamp-mss-to-pmtu
|
||||
|
||||
To compile it as a module, choose M here. If unsure, say N.
|
||||
|
||||
config NETFILTER_XT_MATCH_COMMENT
|
||||
tristate '"comment" match support'
|
||||
depends on NETFILTER_XTABLES
|
||||
|
@ -45,6 +45,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
|
||||
obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG) += xt_NFLOG.o
|
||||
obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o
|
||||
obj-$(CONFIG_NETFILTER_XT_TARGET_SECMARK) += xt_SECMARK.o
|
||||
obj-$(CONFIG_NETFILTER_XT_TARGET_TCPMSS) += xt_TCPMSS.o
|
||||
obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
|
||||
|
||||
# matches
|
||||
|
296
net/netfilter/xt_TCPMSS.c
Normal file
296
net/netfilter/xt_TCPMSS.c
Normal file
@ -0,0 +1,296 @@
|
||||
/*
|
||||
* This is a module which is used for setting the MSS option in TCP packets.
|
||||
*
|
||||
* Copyright (C) 2000 Marc Boucher <marc@mbsi.ca>
|
||||
*
|
||||
* 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/ip.h>
|
||||
#include <linux/ipv6.h>
|
||||
#include <linux/tcp.h>
|
||||
#include <net/ipv6.h>
|
||||
#include <net/tcp.h>
|
||||
|
||||
#include <linux/netfilter_ipv4/ip_tables.h>
|
||||
#include <linux/netfilter_ipv6/ip6_tables.h>
|
||||
#include <linux/netfilter/x_tables.h>
|
||||
#include <linux/netfilter/xt_tcpudp.h>
|
||||
#include <linux/netfilter/xt_TCPMSS.h>
|
||||
|
||||
MODULE_LICENSE("GPL");
|
||||
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
|
||||
MODULE_DESCRIPTION("x_tables TCP MSS modification module");
|
||||
MODULE_ALIAS("ipt_TCPMSS");
|
||||
MODULE_ALIAS("ip6t_TCPMSS");
|
||||
|
||||
static inline unsigned int
|
||||
optlen(const u_int8_t *opt, unsigned int offset)
|
||||
{
|
||||
/* Beware zero-length options: make finite progress */
|
||||
if (opt[offset] <= TCPOPT_NOP || opt[offset+1] == 0)
|
||||
return 1;
|
||||
else
|
||||
return opt[offset+1];
|
||||
}
|
||||
|
||||
static int
|
||||
tcpmss_mangle_packet(struct sk_buff **pskb,
|
||||
const struct xt_tcpmss_info *info,
|
||||
unsigned int tcphoff,
|
||||
unsigned int minlen)
|
||||
{
|
||||
struct tcphdr *tcph;
|
||||
unsigned int tcplen, i;
|
||||
__be16 oldval;
|
||||
u16 newmss;
|
||||
u8 *opt;
|
||||
|
||||
if (!skb_make_writable(pskb, (*pskb)->len))
|
||||
return -1;
|
||||
|
||||
tcplen = (*pskb)->len - tcphoff;
|
||||
tcph = (struct tcphdr *)((*pskb)->nh.raw + tcphoff);
|
||||
|
||||
/* Since it passed flags test in tcp match, we know it is is
|
||||
not a fragment, and has data >= tcp header length. SYN
|
||||
packets should not contain data: if they did, then we risk
|
||||
running over MTU, sending Frag Needed and breaking things
|
||||
badly. --RR */
|
||||
if (tcplen != tcph->doff*4) {
|
||||
if (net_ratelimit())
|
||||
printk(KERN_ERR "xt_TCPMSS: bad length (%u bytes)\n",
|
||||
(*pskb)->len);
|
||||
return -1;
|
||||
}
|
||||
|
||||
if (info->mss == XT_TCPMSS_CLAMP_PMTU) {
|
||||
if (dst_mtu((*pskb)->dst) <= minlen) {
|
||||
if (net_ratelimit())
|
||||
printk(KERN_ERR "xt_TCPMSS: "
|
||||
"unknown or invalid path-MTU (%u)\n",
|
||||
dst_mtu((*pskb)->dst));
|
||||
return -1;
|
||||
}
|
||||
newmss = dst_mtu((*pskb)->dst) - minlen;
|
||||
} else
|
||||
newmss = info->mss;
|
||||
|
||||
opt = (u_int8_t *)tcph;
|
||||
for (i = sizeof(struct tcphdr); i < tcph->doff*4; i += optlen(opt, i)) {
|
||||
if (opt[i] == TCPOPT_MSS && tcph->doff*4 - i >= TCPOLEN_MSS &&
|
||||
opt[i+1] == TCPOLEN_MSS) {
|
||||
u_int16_t oldmss;
|
||||
|
||||
oldmss = (opt[i+2] << 8) | opt[i+3];
|
||||
|
||||
if (info->mss == XT_TCPMSS_CLAMP_PMTU &&
|
||||
oldmss <= newmss)
|
||||
return 0;
|
||||
|
||||
opt[i+2] = (newmss & 0xff00) >> 8;
|
||||
opt[i+3] = (newmss & 0x00ff);
|
||||
|
||||
nf_proto_csum_replace2(&tcph->check, *pskb,
|
||||
htons(oldmss), htons(newmss), 0);
|
||||
return 0;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* MSS Option not found ?! add it..
|
||||
*/
|
||||
if (skb_tailroom((*pskb)) < TCPOLEN_MSS) {
|
||||
struct sk_buff *newskb;
|
||||
|
||||
newskb = skb_copy_expand(*pskb, skb_headroom(*pskb),
|
||||
TCPOLEN_MSS, GFP_ATOMIC);
|
||||
if (!newskb)
|
||||
return -1;
|
||||
kfree_skb(*pskb);
|
||||
*pskb = newskb;
|
||||
tcph = (struct tcphdr *)((*pskb)->nh.raw + tcphoff);
|
||||
}
|
||||
|
||||
skb_put((*pskb), TCPOLEN_MSS);
|
||||
|
||||
opt = (u_int8_t *)tcph + sizeof(struct tcphdr);
|
||||
memmove(opt + TCPOLEN_MSS, opt, tcplen - sizeof(struct tcphdr));
|
||||
|
||||
nf_proto_csum_replace2(&tcph->check, *pskb,
|
||||
htons(tcplen), htons(tcplen + TCPOLEN_MSS), 1);
|
||||
opt[0] = TCPOPT_MSS;
|
||||
opt[1] = TCPOLEN_MSS;
|
||||
opt[2] = (newmss & 0xff00) >> 8;
|
||||
opt[3] = (newmss & 0x00ff);
|
||||
|
||||
nf_proto_csum_replace4(&tcph->check, *pskb, 0, *((__be32 *)opt), 0);
|
||||
|
||||
oldval = ((__be16 *)tcph)[6];
|
||||
tcph->doff += TCPOLEN_MSS/4;
|
||||
nf_proto_csum_replace2(&tcph->check, *pskb,
|
||||
oldval, ((__be16 *)tcph)[6], 0);
|
||||
return TCPOLEN_MSS;
|
||||
}
|
||||
|
||||
static unsigned int
|
||||
xt_tcpmss_target4(struct sk_buff **pskb,
|
||||
const struct net_device *in,
|
||||
const struct net_device *out,
|
||||
unsigned int hooknum,
|
||||
const struct xt_target *target,
|
||||
const void *targinfo)
|
||||
{
|
||||
struct iphdr *iph = (*pskb)->nh.iph;
|
||||
__be16 newlen;
|
||||
int ret;
|
||||
|
||||
ret = tcpmss_mangle_packet(pskb, targinfo, iph->ihl * 4,
|
||||
sizeof(*iph) + sizeof(struct tcphdr));
|
||||
if (ret < 0)
|
||||
return NF_DROP;
|
||||
if (ret > 0) {
|
||||
iph = (*pskb)->nh.iph;
|
||||
newlen = htons(ntohs(iph->tot_len) + ret);
|
||||
nf_csum_replace2(&iph->check, iph->tot_len, newlen);
|
||||
iph->tot_len = newlen;
|
||||
}
|
||||
return XT_CONTINUE;
|
||||
}
|
||||
|
||||
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
|
||||
static unsigned int
|
||||
xt_tcpmss_target6(struct sk_buff **pskb,
|
||||
const struct net_device *in,
|
||||
const struct net_device *out,
|
||||
unsigned int hooknum,
|
||||
const struct xt_target *target,
|
||||
const void *targinfo)
|
||||
{
|
||||
struct ipv6hdr *ipv6h = (*pskb)->nh.ipv6h;
|
||||
u8 nexthdr;
|
||||
int tcphoff;
|
||||
int ret;
|
||||
|
||||
nexthdr = ipv6h->nexthdr;
|
||||
tcphoff = ipv6_skip_exthdr(*pskb, sizeof(*ipv6h), &nexthdr);
|
||||
if (tcphoff < 0) {
|
||||
WARN_ON(1);
|
||||
return NF_DROP;
|
||||
}
|
||||
ret = tcpmss_mangle_packet(pskb, targinfo, tcphoff,
|
||||
sizeof(*ipv6h) + sizeof(struct tcphdr));
|
||||
if (ret < 0)
|
||||
return NF_DROP;
|
||||
if (ret > 0) {
|
||||
ipv6h = (*pskb)->nh.ipv6h;
|
||||
ipv6h->payload_len = htons(ntohs(ipv6h->payload_len) + ret);
|
||||
}
|
||||
return XT_CONTINUE;
|
||||
}
|
||||
#endif
|
||||
|
||||
#define TH_SYN 0x02
|
||||
|
||||
/* Must specify -p tcp --syn */
|
||||
static inline int find_syn_match(const struct xt_entry_match *m)
|
||||
{
|
||||
const struct xt_tcp *tcpinfo = (const struct xt_tcp *)m->data;
|
||||
|
||||
if (strcmp(m->u.kernel.match->name, "tcp") == 0 &&
|
||||
tcpinfo->flg_cmp & TH_SYN &&
|
||||
!(tcpinfo->invflags & XT_TCP_INV_FLAGS))
|
||||
return 1;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int
|
||||
xt_tcpmss_checkentry4(const char *tablename,
|
||||
const void *entry,
|
||||
const struct xt_target *target,
|
||||
void *targinfo,
|
||||
unsigned int hook_mask)
|
||||
{
|
||||
const struct xt_tcpmss_info *info = targinfo;
|
||||
const struct ipt_entry *e = entry;
|
||||
|
||||
if (info->mss == XT_TCPMSS_CLAMP_PMTU &&
|
||||
(hook_mask & ~((1 << NF_IP_FORWARD) |
|
||||
(1 << NF_IP_LOCAL_OUT) |
|
||||
(1 << NF_IP_POST_ROUTING))) != 0) {
|
||||
printk("xt_TCPMSS: path-MTU clamping only supported in "
|
||||
"FORWARD, OUTPUT and POSTROUTING hooks\n");
|
||||
return 0;
|
||||
}
|
||||
if (IPT_MATCH_ITERATE(e, find_syn_match))
|
||||
return 1;
|
||||
printk("xt_TCPMSS: Only works on TCP SYN packets\n");
|
||||
return 0;
|
||||
}
|
||||
|
||||
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
|
||||
static int
|
||||
xt_tcpmss_checkentry6(const char *tablename,
|
||||
const void *entry,
|
||||
const struct xt_target *target,
|
||||
void *targinfo,
|
||||
unsigned int hook_mask)
|
||||
{
|
||||
const struct xt_tcpmss_info *info = targinfo;
|
||||
const struct ip6t_entry *e = entry;
|
||||
|
||||
if (info->mss == XT_TCPMSS_CLAMP_PMTU &&
|
||||
(hook_mask & ~((1 << NF_IP6_FORWARD) |
|
||||
(1 << NF_IP6_LOCAL_OUT) |
|
||||
(1 << NF_IP6_POST_ROUTING))) != 0) {
|
||||
printk("xt_TCPMSS: path-MTU clamping only supported in "
|
||||
"FORWARD, OUTPUT and POSTROUTING hooks\n");
|
||||
return 0;
|
||||
}
|
||||
if (IP6T_MATCH_ITERATE(e, find_syn_match))
|
||||
return 1;
|
||||
printk("xt_TCPMSS: Only works on TCP SYN packets\n");
|
||||
return 0;
|
||||
}
|
||||
#endif
|
||||
|
||||
static struct xt_target xt_tcpmss_reg[] = {
|
||||
{
|
||||
.family = AF_INET,
|
||||
.name = "TCPMSS",
|
||||
.checkentry = xt_tcpmss_checkentry4,
|
||||
.target = xt_tcpmss_target4,
|
||||
.targetsize = sizeof(struct xt_tcpmss_info),
|
||||
.proto = IPPROTO_TCP,
|
||||
.me = THIS_MODULE,
|
||||
},
|
||||
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
|
||||
{
|
||||
.family = AF_INET6,
|
||||
.name = "TCPMSS",
|
||||
.checkentry = xt_tcpmss_checkentry6,
|
||||
.target = xt_tcpmss_target6,
|
||||
.targetsize = sizeof(struct xt_tcpmss_info),
|
||||
.proto = IPPROTO_TCP,
|
||||
.me = THIS_MODULE,
|
||||
},
|
||||
#endif
|
||||
};
|
||||
|
||||
static int __init xt_tcpmss_init(void)
|
||||
{
|
||||
return xt_register_targets(xt_tcpmss_reg, ARRAY_SIZE(xt_tcpmss_reg));
|
||||
}
|
||||
|
||||
static void __exit xt_tcpmss_fini(void)
|
||||
{
|
||||
xt_unregister_targets(xt_tcpmss_reg, ARRAY_SIZE(xt_tcpmss_reg));
|
||||
}
|
||||
|
||||
module_init(xt_tcpmss_init);
|
||||
module_exit(xt_tcpmss_fini);
|
Loading…
Reference in New Issue
Block a user