/* (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.
*
* 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
* - enable working with Layer 3 protocol independent connection tracking.
*
* Derived from net/ipv4/netfilter/ip_conntrack_proto_icmp.c
*/
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/netfilter.h>
#include <linux/in.h>
#include <linux/icmp.h>
#include <linux/seq_file.h>
#include <net/ip.h>
#include <net/checksum.h>
#include <linux/netfilter_ipv4.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#include <net/netfilter/nf_conntrack_protocol.h>
#include <net/netfilter/nf_conntrack_core.h>
unsigned long nf_ct_icmp_timeout __read_mostly = 30*HZ;
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
static int icmp_pkt_to_tuple(const struct sk_buff *skb,
unsigned int dataoff,
struct nf_conntrack_tuple *tuple)
{
struct icmphdr _hdr, *hp;
hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
if (hp == NULL)
return 0;
tuple->dst.u.icmp.type = hp->type;
tuple->src.u.icmp.id = hp->un.echo.id;
tuple->dst.u.icmp.code = hp->code;
return 1;
}
/* Add 1; spaces filled with 0. */
static const u_int8_t invmap[] = {
[ICMP_ECHO] = ICMP_ECHOREPLY + 1,
[ICMP_ECHOREPLY] = ICMP_ECHO + 1,
[ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
[ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
[ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
[ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
[ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
[ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
};
static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_tuple *orig)
{
if (orig->dst.u.icmp.type >= sizeof(invmap)
|| !invmap[orig->dst.u.icmp.type])
return 0;
tuple->src.u.icmp.id = orig->src.u.icmp.id;
tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
return 1;
}
/* Print out the per-protocol part of the tuple. */
static int icmp_print_tuple(struct seq_file *s,
const struct nf_conntrack_tuple *tuple)
{
return seq_printf(s, "type=%u code=%u id=%u ",
tuple->dst.u.icmp.type,
tuple->dst.u.icmp.code,
ntohs(tuple->src.u.icmp.id));
}
/* Print out the private part of the conntrack. */
static int icmp_print_conntrack(struct seq_file *s,
const struct nf_conn *conntrack)
{
return 0;
}
/* Returns verdict for packet, or -1 for invalid. */
static int icmp_packet(struct nf_conn *ct,
const struct sk_buff *skb,
unsigned int dataoff,
enum ip_conntrack_info ctinfo,
int pf,
unsigned int hooknum)
{
/* Try to delete connection immediately after all replies:
won't actually vanish as we still have skb, and del_timer
means this will only run once even if count hits zero twice
(theoretically possible with SMP) */
if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
if (atomic_dec_and_test(&ct->proto.icmp.count)
&& del_timer(&ct->timeout))
ct->timeout.function((unsigned long)ct);
} else {
atomic_inc(&ct->proto.icmp.count);
nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
}
return NF_ACCEPT;
}
/* Called when a new connection for this protocol found. */
static int icmp_new(struct nf_conn *conntrack,
const struct sk_buff *skb, unsigned int dataoff)
{
static const u_int8_t valid_new[] = {
[ICMP_ECHO] = 1,
[ICMP_TIMESTAMP] = 1,
[ICMP_INFO_REQUEST] = 1,
[ICMP_ADDRESS] = 1
};
if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
|| !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
/* Can't create a new ICMP `conn' with this. */
DEBUGP("icmp: can't create new conn with type %u\n",
conntrack->tuplehash[0].tuple.dst.u.icmp.type);
NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
return 0;
}
atomic_set(&conntrack->proto.icmp.count, 0);
return 1;
}
extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4;
/* Returns conntrack if it dealt with ICMP, and filled in skb fields */
static int
icmp_error_message(struct sk_buff *skb,
enum ip_conntrack_info *ctinfo,
unsigned int hooknum)
{
struct nf_conntrack_tuple innertuple, origtuple;
struct {
struct icmphdr icmp;
struct iphdr ip;
} _in, *inside;
struct nf_conntrack_protocol *innerproto;
struct nf_conntrack_tuple_hash *h;
int dataoff;
NF_CT_ASSERT(skb->nfct == NULL);
/* Not enough header? */
inside = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_in), &_in);
if (inside == NULL)
return -NF_ACCEPT;
/* Ignore ICMP's containing fragments (shouldn't happen) */
if (inside->ip.frag_off & htons(IP_OFFSET)) {
DEBUGP("icmp_error_message: fragment of proto %u\n",
inside->ip.protocol);
return -NF_ACCEPT;
}
innerproto = __nf_ct_proto_find(PF_INET, inside->ip.protocol);
dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp);
/* Are they talking about one of our connections? */
if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET,
inside->ip.protocol, &origtuple,
&nf_conntrack_l3proto_ipv4, innerproto)) {
DEBUGP("icmp_error_message: ! get_tuple p=%u",
inside->ip.protocol);
return -NF_ACCEPT;
}
/* Ordinarily, we'd expect the inverted tupleproto, but it's
been preserved inside the ICMP. */
if (!nf_ct_invert_tuple(&innertuple, &origtuple,
&nf_conntrack_l3proto_ipv4, innerproto)) {
DEBUGP("icmp_error_message: no match\n");
return -NF_ACCEPT;
}
*ctinfo = IP_CT_RELATED;
h = nf_conntrack_find_get(&innertuple, NULL);
if (!h) {
/* Locally generated ICMPs will match inverted if they
haven't been SNAT'ed yet */
/* FIXME: NAT code has to handle half-done double NAT --RR */
if (hooknum == NF_IP_LOCAL_OUT)
h = nf_conntrack_find_get(&origtuple, NULL);
if (!h) {
DEBUGP("icmp_error_message: no match\n");
return -NF_ACCEPT;
}
/* Reverse direction from that found */
if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
*ctinfo += IP_CT_IS_REPLY;
} else {
if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
*ctinfo += IP_CT_IS_REPLY;
}
/* Update skb to refer to this connection */
skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
skb->nfctinfo = *ctinfo;
return -NF_ACCEPT;
}
/* Small and modified version of icmp_rcv */
static int
icmp_error(struct sk_buff *skb, unsigned int dataoff,
enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
{
struct icmphdr _ih, *icmph;
/* Not enough header? */
icmph = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_ih), &_ih);
if (icmph == NULL) {
if (LOG_INVALID(IPPROTO_ICMP))
nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
"nf_ct_icmp: short packet ");
return -NF_ACCEPT;
}
/* See ip_conntrack_proto_tcp.c */
if (nf_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING &&
nf_ip_checksum(skb, hooknum, dataoff, 0)) {
if (LOG_INVALID(IPPROTO_ICMP))
nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
"nf_ct_icmp: bad HW ICMP checksum ");
return -NF_ACCEPT;
}
/*
* 18 is the highest 'known' ICMP type. Anything else is a mystery
*
* RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
* discarded.
*/
if (icmph->type > NR_ICMP_TYPES) {
if (LOG_INVALID(IPPROTO_ICMP))
nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
"nf_ct_icmp: invalid ICMP type ");
return -NF_ACCEPT;
}
/* Need to track icmp error message? */
if (icmph->type != ICMP_DEST_UNREACH
&& icmph->type != ICMP_SOURCE_QUENCH
&& icmph->type != ICMP_TIME_EXCEEDED
&& icmph->type != ICMP_PARAMETERPROB
&& icmph->type != ICMP_REDIRECT)
return NF_ACCEPT;
return icmp_error_message(skb, ctinfo, hooknum);
}
#if defined(CONFIG_NF_CT_NETLINK) || \
defined(CONFIG_NF_CT_NETLINK_MODULE)
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>
static int icmp_tuple_to_nfattr(struct sk_buff *skb,
const struct nf_conntrack_tuple *t)
{
NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t),
&t->src.u.icmp.id);
NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t),
&t->dst.u.icmp.type);
NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t),
&t->dst.u.icmp.code);
return 0;
nfattr_failure:
return -1;
}
static const size_t cta_min_proto[CTA_PROTO_MAX] = {
[CTA_PROTO_ICMP_TYPE-1] = sizeof(u_int8_t),
[CTA_PROTO_ICMP_CODE-1] = sizeof(u_int8_t),
[CTA_PROTO_ICMP_ID-1] = sizeof(u_int16_t)
};
static int icmp_nfattr_to_tuple(struct nfattr *tb[],
struct nf_conntrack_tuple *tuple)
{
if (!tb[CTA_PROTO_ICMP_TYPE-1]
|| !tb[CTA_PROTO_ICMP_CODE-1]
|| !tb[CTA_PROTO_ICMP_ID-1])
return -EINVAL;
if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
return -EINVAL;
tuple->dst.u.icmp.type =
*(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]);
tuple->dst.u.icmp.code =
*(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]);
tuple->src.u.icmp.id =
*(u_int16_t *)NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]);
if (tuple->dst.u.icmp.type >= sizeof(invmap)
|| !invmap[tuple->dst.u.icmp.type])
return -EINVAL;
return 0;
}
#endif
struct nf_conntrack_protocol nf_conntrack_protocol_icmp =
{
.list = { NULL, NULL },
.l3proto = PF_INET,
.proto = IPPROTO_ICMP,
.name = "icmp",
.pkt_to_tuple = icmp_pkt_to_tuple,
.invert_tuple = icmp_invert_tuple,
.print_tuple = icmp_print_tuple,
.print_conntrack = icmp_print_conntrack,
.packet = icmp_packet,
.new = icmp_new,
.error = icmp_error,
.destroy = NULL,
.me = NULL,
#if defined(CONFIG_NF_CT_NETLINK) || \
defined(CONFIG_NF_CT_NETLINK_MODULE)
.tuple_to_nfattr = icmp_tuple_to_nfattr,
.nfattr_to_tuple = icmp_nfattr_to_tuple,
#endif
};
EXPORT_SYMBOL(nf_conntrack_protocol_icmp);
