Commit 764d8a9f authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[NETFILTER]: Add IPv6 REJECT target



Originally written by Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>,
taken from netfilter patch-o-matic and fixed up to work with current
kernels.
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7567662b
#ifndef _IP6T_REJECT_H
#define _IP6T_REJECT_H
enum ip6t_reject_with {
IP6T_ICMP6_NO_ROUTE,
IP6T_ICMP6_ADM_PROHIBITED,
IP6T_ICMP6_NOT_NEIGHBOUR,
IP6T_ICMP6_ADDR_UNREACH,
IP6T_ICMP6_PORT_UNREACH,
IP6T_ICMP6_ECHOREPLY,
IP6T_TCP_RESET
};
struct ip6t_reject_info {
u_int32_t with; /* reject type */
};
#endif /*_IP6T_REJECT_H*/
......@@ -199,6 +199,16 @@ config IP6_NF_TARGET_LOG
To compile it as a module, choose M here. If unsure, say N.
config IP6_NF_TARGET_REJECT
tristate "REJECT target support"
depends on IP6_NF_FILTER
help
The REJECT target allows a filtering rule to specify that an ICMPv6
error should be issued in response to an incoming packet, rather
than silently being dropped.
To compile it as a module, choose M here. If unsure, say N.
# if [ "$CONFIG_IP6_NF_FILTER" != "n" ]; then
# dep_tristate ' REJECT target support' CONFIG_IP6_NF_TARGET_REJECT $CONFIG_IP6_NF_FILTER
# if [ "$CONFIG_EXPERIMENTAL" = "y" ]; then
......
......@@ -24,4 +24,5 @@ obj-$(CONFIG_IP6_NF_QUEUE) += ip6_queue.o
obj-$(CONFIG_IP6_NF_TARGET_LOG) += ip6t_LOG.o
obj-$(CONFIG_IP6_NF_RAW) += ip6table_raw.o
obj-$(CONFIG_IP6_NF_MATCH_HL) += ip6t_hl.o
obj-$(CONFIG_IP6_NF_TARGET_REJECT) += ip6t_REJECT.o
obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += ip6t_NFQUEUE.o
/*
* IP6 tables REJECT target module
* Linux INET6 implementation
*
* Copyright (C)2003 USAGI/WIDE Project
*
* Authors:
* Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
*
* Based on net/ipv4/netfilter/ipt_REJECT.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmpv6.h>
#include <linux/netdevice.h>
#include <net/ipv6.h>
#include <net/tcp.h>
#include <net/icmp.h>
#include <net/ip6_checksum.h>
#include <net/ip6_fib.h>
#include <net/ip6_route.h>
#include <net/flow.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_REJECT.h>
MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
MODULE_DESCRIPTION("IP6 tables REJECT target module");
MODULE_LICENSE("GPL");
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
/* Send RST reply */
static void send_reset(struct sk_buff *oldskb)
{
struct sk_buff *nskb;
struct tcphdr otcph, *tcph;
unsigned int otcplen, hh_len;
int tcphoff, needs_ack;
struct ipv6hdr *oip6h = oldskb->nh.ipv6h, *ip6h;
struct dst_entry *dst = NULL;
u8 proto;
struct flowi fl;
if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
(!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
DEBUGP("ip6t_REJECT: addr is not unicast.\n");
return;
}
proto = oip6h->nexthdr;
tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
if ((tcphoff < 0) || (tcphoff > oldskb->len)) {
DEBUGP("ip6t_REJECT: Can't get TCP header.\n");
return;
}
otcplen = oldskb->len - tcphoff;
/* IP header checks: fragment, too short. */
if ((proto != IPPROTO_TCP) || (otcplen < sizeof(struct tcphdr))) {
DEBUGP("ip6t_REJECT: proto(%d) != IPPROTO_TCP, or too short. otcplen = %d\n",
proto, otcplen);
return;
}
if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
BUG();
/* No RST for RST. */
if (otcph.rst) {
DEBUGP("ip6t_REJECT: RST is set\n");
return;
}
/* Check checksum. */
if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
skb_checksum(oldskb, tcphoff, otcplen, 0))) {
DEBUGP("ip6t_REJECT: TCP checksum is invalid\n");
return;
}
memset(&fl, 0, sizeof(fl));
fl.proto = IPPROTO_TCP;
ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
fl.fl_ip_sport = otcph.dest;
fl.fl_ip_dport = otcph.source;
dst = ip6_route_output(NULL, &fl);
if (dst == NULL)
return;
if (dst->error ||
xfrm_lookup(&dst, &fl, NULL, 0)) {
dst_release(dst);
return;
}
hh_len = (dst->dev->hard_header_len + 15)&~15;
nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
+ sizeof(struct tcphdr) + dst->trailer_len,
GFP_ATOMIC);
if (!nskb) {
if (net_ratelimit())
printk("ip6t_REJECT: Can't alloc skb\n");
dst_release(dst);
return;
}
nskb->dst = dst;
skb_reserve(nskb, hh_len + dst->header_len);
ip6h = nskb->nh.ipv6h = (struct ipv6hdr *)
skb_put(nskb, sizeof(struct ipv6hdr));
ip6h->version = 6;
ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
ip6h->nexthdr = IPPROTO_TCP;
ip6h->payload_len = htons(sizeof(struct tcphdr));
ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
/* Truncate to length (no data) */
tcph->doff = sizeof(struct tcphdr)/4;
tcph->source = otcph.dest;
tcph->dest = otcph.source;
if (otcph.ack) {
needs_ack = 0;
tcph->seq = otcph.ack_seq;
tcph->ack_seq = 0;
} else {
needs_ack = 1;
tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
+ otcplen - (otcph.doff<<2));
tcph->seq = 0;
}
/* Reset flags */
((u_int8_t *)tcph)[13] = 0;
tcph->rst = 1;
tcph->ack = needs_ack;
tcph->window = 0;
tcph->urg_ptr = 0;
tcph->check = 0;
/* Adjust TCP checksum */
tcph->check = csum_ipv6_magic(&nskb->nh.ipv6h->saddr,
&nskb->nh.ipv6h->daddr,
sizeof(struct tcphdr), IPPROTO_TCP,
csum_partial((char *)tcph,
sizeof(struct tcphdr), 0));
NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
dst_output);
}
static inline void
send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
{
if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
skb_in->dev = &loopback_dev;
icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
}
static unsigned int reject6_target(struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const void *targinfo,
void *userinfo)
{
const struct ip6t_reject_info *reject = targinfo;
DEBUGP(KERN_DEBUG "%s: medium point\n", __FUNCTION__);
/* WARNING: This code causes reentry within ip6tables.
This means that the ip6tables jump stack is now crap. We
must return an absolute verdict. --RR */
switch (reject->with) {
case IP6T_ICMP6_NO_ROUTE:
send_unreach(*pskb, ICMPV6_NOROUTE, hooknum);
break;
case IP6T_ICMP6_ADM_PROHIBITED:
send_unreach(*pskb, ICMPV6_ADM_PROHIBITED, hooknum);
break;
case IP6T_ICMP6_NOT_NEIGHBOUR:
send_unreach(*pskb, ICMPV6_NOT_NEIGHBOUR, hooknum);
break;
case IP6T_ICMP6_ADDR_UNREACH:
send_unreach(*pskb, ICMPV6_ADDR_UNREACH, hooknum);
break;
case IP6T_ICMP6_PORT_UNREACH:
send_unreach(*pskb, ICMPV6_PORT_UNREACH, hooknum);
break;
case IP6T_ICMP6_ECHOREPLY:
/* Do nothing */
break;
case IP6T_TCP_RESET:
send_reset(*pskb);
break;
default:
if (net_ratelimit())
printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
break;
}
return NF_DROP;
}
static int check(const char *tablename,
const struct ip6t_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
const struct ip6t_reject_info *rejinfo = targinfo;
if (targinfosize != IP6T_ALIGN(sizeof(struct ip6t_reject_info))) {
DEBUGP("ip6t_REJECT: targinfosize %u != 0\n", targinfosize);
return 0;
}
/* Only allow these for packet filtering. */
if (strcmp(tablename, "filter") != 0) {
DEBUGP("ip6t_REJECT: bad table `%s'.\n", tablename);
return 0;
}
if ((hook_mask & ~((1 << NF_IP6_LOCAL_IN)
| (1 << NF_IP6_FORWARD)
| (1 << NF_IP6_LOCAL_OUT))) != 0) {
DEBUGP("ip6t_REJECT: bad hook mask %X\n", hook_mask);
return 0;
}
if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
return 0;
} else if (rejinfo->with == IP6T_TCP_RESET) {
/* Must specify that it's a TCP packet */
if (e->ipv6.proto != IPPROTO_TCP
|| (e->ipv6.invflags & IP6T_INV_PROTO)) {
DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
return 0;
}
}
return 1;
}
static struct ip6t_target ip6t_reject_reg = {
.name = "REJECT",
.target = reject6_target,
.checkentry = check,
.me = THIS_MODULE
};
static int __init init(void)
{
if (ip6t_register_target(&ip6t_reject_reg))
return -EINVAL;
return 0;
}
static void __exit fini(void)
{
ip6t_unregister_target(&ip6t_reject_reg);
}
module_init(init);
module_exit(fini);
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