mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-25 02:09:42 +00:00
![Patrick McHardy](/assets/img/avatar_default.png)
Besides removing lots of duplicate code, all converted users benefit from improved HW checksum error handling. Tested with and without HW checksums in almost all combinations. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
320 lines
7.9 KiB
C
320 lines
7.9 KiB
C
/*
|
|
* This is a module which is used for rejecting packets.
|
|
* Added support for customized reject packets (Jozsef Kadlecsik).
|
|
* Added support for ICMP type-3-code-13 (Maciej Soltysiak). [RFC 1812]
|
|
*/
|
|
|
|
/* (C) 1999-2001 Paul `Rusty' Russell
|
|
* (C) 2002-2004 Netfilter Core Team <coreteam@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/config.h>
|
|
#include <linux/module.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/ip.h>
|
|
#include <linux/udp.h>
|
|
#include <linux/icmp.h>
|
|
#include <net/icmp.h>
|
|
#include <net/ip.h>
|
|
#include <net/tcp.h>
|
|
#include <net/route.h>
|
|
#include <net/dst.h>
|
|
#include <linux/netfilter_ipv4/ip_tables.h>
|
|
#include <linux/netfilter_ipv4/ipt_REJECT.h>
|
|
#ifdef CONFIG_BRIDGE_NETFILTER
|
|
#include <linux/netfilter_bridge.h>
|
|
#endif
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
|
|
MODULE_DESCRIPTION("iptables REJECT target module");
|
|
|
|
#if 0
|
|
#define DEBUGP printk
|
|
#else
|
|
#define DEBUGP(format, args...)
|
|
#endif
|
|
|
|
static inline struct rtable *route_reverse(struct sk_buff *skb,
|
|
struct tcphdr *tcph, int hook)
|
|
{
|
|
struct iphdr *iph = skb->nh.iph;
|
|
struct dst_entry *odst;
|
|
struct flowi fl = {};
|
|
struct rtable *rt;
|
|
|
|
/* We don't require ip forwarding to be enabled to be able to
|
|
* send a RST reply for bridged traffic. */
|
|
if (hook != NF_IP_FORWARD
|
|
#ifdef CONFIG_BRIDGE_NETFILTER
|
|
|| (skb->nf_bridge && skb->nf_bridge->mask & BRNF_BRIDGED)
|
|
#endif
|
|
) {
|
|
fl.nl_u.ip4_u.daddr = iph->saddr;
|
|
if (hook == NF_IP_LOCAL_IN)
|
|
fl.nl_u.ip4_u.saddr = iph->daddr;
|
|
fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
|
|
|
|
if (ip_route_output_key(&rt, &fl) != 0)
|
|
return NULL;
|
|
} else {
|
|
/* non-local src, find valid iif to satisfy
|
|
* rp-filter when calling ip_route_input. */
|
|
fl.nl_u.ip4_u.daddr = iph->daddr;
|
|
if (ip_route_output_key(&rt, &fl) != 0)
|
|
return NULL;
|
|
|
|
odst = skb->dst;
|
|
if (ip_route_input(skb, iph->saddr, iph->daddr,
|
|
RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
|
|
dst_release(&rt->u.dst);
|
|
return NULL;
|
|
}
|
|
dst_release(&rt->u.dst);
|
|
rt = (struct rtable *)skb->dst;
|
|
skb->dst = odst;
|
|
|
|
fl.nl_u.ip4_u.daddr = iph->saddr;
|
|
fl.nl_u.ip4_u.saddr = iph->daddr;
|
|
fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
|
|
}
|
|
|
|
if (rt->u.dst.error) {
|
|
dst_release(&rt->u.dst);
|
|
return NULL;
|
|
}
|
|
|
|
fl.proto = IPPROTO_TCP;
|
|
fl.fl_ip_sport = tcph->dest;
|
|
fl.fl_ip_dport = tcph->source;
|
|
|
|
xfrm_lookup((struct dst_entry **)&rt, &fl, NULL, 0);
|
|
|
|
return rt;
|
|
}
|
|
|
|
/* Send RST reply */
|
|
static void send_reset(struct sk_buff *oldskb, int hook)
|
|
{
|
|
struct sk_buff *nskb;
|
|
struct iphdr *iph = oldskb->nh.iph;
|
|
struct tcphdr _otcph, *oth, *tcph;
|
|
struct rtable *rt;
|
|
u_int16_t tmp_port;
|
|
u_int32_t tmp_addr;
|
|
int needs_ack;
|
|
int hh_len;
|
|
|
|
/* IP header checks: fragment. */
|
|
if (oldskb->nh.iph->frag_off & htons(IP_OFFSET))
|
|
return;
|
|
|
|
oth = skb_header_pointer(oldskb, oldskb->nh.iph->ihl * 4,
|
|
sizeof(_otcph), &_otcph);
|
|
if (oth == NULL)
|
|
return;
|
|
|
|
/* No RST for RST. */
|
|
if (oth->rst)
|
|
return;
|
|
|
|
/* Check checksum */
|
|
if (nf_ip_checksum(oldskb, hook, iph->ihl * 4, IPPROTO_TCP))
|
|
return;
|
|
|
|
if ((rt = route_reverse(oldskb, oth, hook)) == NULL)
|
|
return;
|
|
|
|
hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
|
|
|
|
/* We need a linear, writeable skb. We also need to expand
|
|
headroom in case hh_len of incoming interface < hh_len of
|
|
outgoing interface */
|
|
nskb = skb_copy_expand(oldskb, hh_len, skb_tailroom(oldskb),
|
|
GFP_ATOMIC);
|
|
if (!nskb) {
|
|
dst_release(&rt->u.dst);
|
|
return;
|
|
}
|
|
|
|
dst_release(nskb->dst);
|
|
nskb->dst = &rt->u.dst;
|
|
|
|
/* This packet will not be the same as the other: clear nf fields */
|
|
nf_reset(nskb);
|
|
nskb->nfmark = 0;
|
|
|
|
tcph = (struct tcphdr *)((u_int32_t*)nskb->nh.iph + nskb->nh.iph->ihl);
|
|
|
|
/* Swap source and dest */
|
|
tmp_addr = nskb->nh.iph->saddr;
|
|
nskb->nh.iph->saddr = nskb->nh.iph->daddr;
|
|
nskb->nh.iph->daddr = tmp_addr;
|
|
tmp_port = tcph->source;
|
|
tcph->source = tcph->dest;
|
|
tcph->dest = tmp_port;
|
|
|
|
/* Truncate to length (no data) */
|
|
tcph->doff = sizeof(struct tcphdr)/4;
|
|
skb_trim(nskb, nskb->nh.iph->ihl*4 + sizeof(struct tcphdr));
|
|
nskb->nh.iph->tot_len = htons(nskb->len);
|
|
|
|
if (tcph->ack) {
|
|
needs_ack = 0;
|
|
tcph->seq = oth->ack_seq;
|
|
tcph->ack_seq = 0;
|
|
} else {
|
|
needs_ack = 1;
|
|
tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin
|
|
+ oldskb->len - oldskb->nh.iph->ihl*4
|
|
- (oth->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;
|
|
|
|
/* Adjust TCP checksum */
|
|
tcph->check = 0;
|
|
tcph->check = tcp_v4_check(tcph, sizeof(struct tcphdr),
|
|
nskb->nh.iph->saddr,
|
|
nskb->nh.iph->daddr,
|
|
csum_partial((char *)tcph,
|
|
sizeof(struct tcphdr), 0));
|
|
|
|
/* Adjust IP TTL, DF */
|
|
nskb->nh.iph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT);
|
|
/* Set DF, id = 0 */
|
|
nskb->nh.iph->frag_off = htons(IP_DF);
|
|
nskb->nh.iph->id = 0;
|
|
|
|
/* Adjust IP checksum */
|
|
nskb->nh.iph->check = 0;
|
|
nskb->nh.iph->check = ip_fast_csum((unsigned char *)nskb->nh.iph,
|
|
nskb->nh.iph->ihl);
|
|
|
|
/* "Never happens" */
|
|
if (nskb->len > dst_mtu(nskb->dst))
|
|
goto free_nskb;
|
|
|
|
nf_ct_attach(nskb, oldskb);
|
|
|
|
NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
|
|
dst_output);
|
|
return;
|
|
|
|
free_nskb:
|
|
kfree_skb(nskb);
|
|
}
|
|
|
|
static inline void send_unreach(struct sk_buff *skb_in, int code)
|
|
{
|
|
icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);
|
|
}
|
|
|
|
static unsigned int reject(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,
|
|
void *userinfo)
|
|
{
|
|
const struct ipt_reject_info *reject = targinfo;
|
|
|
|
/* Our naive response construction doesn't deal with IP
|
|
options, and probably shouldn't try. */
|
|
if ((*pskb)->nh.iph->ihl<<2 != sizeof(struct iphdr))
|
|
return NF_DROP;
|
|
|
|
/* WARNING: This code causes reentry within iptables.
|
|
This means that the iptables jump stack is now crap. We
|
|
must return an absolute verdict. --RR */
|
|
switch (reject->with) {
|
|
case IPT_ICMP_NET_UNREACHABLE:
|
|
send_unreach(*pskb, ICMP_NET_UNREACH);
|
|
break;
|
|
case IPT_ICMP_HOST_UNREACHABLE:
|
|
send_unreach(*pskb, ICMP_HOST_UNREACH);
|
|
break;
|
|
case IPT_ICMP_PROT_UNREACHABLE:
|
|
send_unreach(*pskb, ICMP_PROT_UNREACH);
|
|
break;
|
|
case IPT_ICMP_PORT_UNREACHABLE:
|
|
send_unreach(*pskb, ICMP_PORT_UNREACH);
|
|
break;
|
|
case IPT_ICMP_NET_PROHIBITED:
|
|
send_unreach(*pskb, ICMP_NET_ANO);
|
|
break;
|
|
case IPT_ICMP_HOST_PROHIBITED:
|
|
send_unreach(*pskb, ICMP_HOST_ANO);
|
|
break;
|
|
case IPT_ICMP_ADMIN_PROHIBITED:
|
|
send_unreach(*pskb, ICMP_PKT_FILTERED);
|
|
break;
|
|
case IPT_TCP_RESET:
|
|
send_reset(*pskb, hooknum);
|
|
case IPT_ICMP_ECHOREPLY:
|
|
/* Doesn't happen. */
|
|
break;
|
|
}
|
|
|
|
return NF_DROP;
|
|
}
|
|
|
|
static int check(const char *tablename,
|
|
const void *e_void,
|
|
const struct xt_target *target,
|
|
void *targinfo,
|
|
unsigned int targinfosize,
|
|
unsigned int hook_mask)
|
|
{
|
|
const struct ipt_reject_info *rejinfo = targinfo;
|
|
const struct ipt_entry *e = e_void;
|
|
|
|
if (rejinfo->with == IPT_ICMP_ECHOREPLY) {
|
|
printk("REJECT: ECHOREPLY no longer supported.\n");
|
|
return 0;
|
|
} else if (rejinfo->with == IPT_TCP_RESET) {
|
|
/* Must specify that it's a TCP packet */
|
|
if (e->ip.proto != IPPROTO_TCP
|
|
|| (e->ip.invflags & IPT_INV_PROTO)) {
|
|
DEBUGP("REJECT: TCP_RESET invalid for non-tcp\n");
|
|
return 0;
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static struct ipt_target ipt_reject_reg = {
|
|
.name = "REJECT",
|
|
.target = reject,
|
|
.targetsize = sizeof(struct ipt_reject_info),
|
|
.table = "filter",
|
|
.hooks = (1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) |
|
|
(1 << NF_IP_LOCAL_OUT),
|
|
.checkentry = check,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
static int __init ipt_reject_init(void)
|
|
{
|
|
return ipt_register_target(&ipt_reject_reg);
|
|
}
|
|
|
|
static void __exit ipt_reject_fini(void)
|
|
{
|
|
ipt_unregister_target(&ipt_reject_reg);
|
|
}
|
|
|
|
module_init(ipt_reject_init);
|
|
module_exit(ipt_reject_fini);
|