mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-25 02:09:42 +00:00
![Harald Welte](/assets/img/avatar_default.png)
When you've enabled conntrack and NAT as a module (standard case in all distributions), and you've also enabled the new conntrack netlink interface, loading ip_conntrack_netlink.ko will auto-load iptable_nat.ko. This causes a huge performance penalty, since for every packet you iterate the nat code, even if you don't want it. This patch splits iptable_nat.ko into the NAT core (ip_nat.ko) and the iptables frontend (iptable_nat.ko). Threfore, ip_conntrack_netlink.ko will only pull ip_nat.ko, but not the frontend. ip_nat.ko will "only" allocate some resources, but not affect runtime performance. This separation is also a nice step in anticipation of new packet filters (nf-hipac, ipset, pkttables) being able to use the NAT core. Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: David S. Miller <davem@davemloft.net>
431 lines
12 KiB
C
431 lines
12 KiB
C
/* ip_nat_helper.c - generic support functions for NAT helpers
|
|
*
|
|
* (C) 2000-2002 Harald Welte <laforge@netfilter.org>
|
|
* (C) 2003-2004 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.
|
|
*
|
|
* 14 Jan 2002 Harald Welte <laforge@gnumonks.org>:
|
|
* - add support for SACK adjustment
|
|
* 14 Mar 2002 Harald Welte <laforge@gnumonks.org>:
|
|
* - merge SACK support into newnat API
|
|
* 16 Aug 2002 Brian J. Murrell <netfilter@interlinx.bc.ca>:
|
|
* - make ip_nat_resize_packet more generic (TCP and UDP)
|
|
* - add ip_nat_mangle_udp_packet
|
|
*/
|
|
#include <linux/config.h>
|
|
#include <linux/module.h>
|
|
#include <linux/kmod.h>
|
|
#include <linux/types.h>
|
|
#include <linux/timer.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/netfilter_ipv4.h>
|
|
#include <net/checksum.h>
|
|
#include <net/icmp.h>
|
|
#include <net/ip.h>
|
|
#include <net/tcp.h>
|
|
#include <net/udp.h>
|
|
|
|
#define ASSERT_READ_LOCK(x)
|
|
#define ASSERT_WRITE_LOCK(x)
|
|
|
|
#include <linux/netfilter_ipv4/ip_conntrack.h>
|
|
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
|
|
#include <linux/netfilter_ipv4/ip_nat.h>
|
|
#include <linux/netfilter_ipv4/ip_nat_protocol.h>
|
|
#include <linux/netfilter_ipv4/ip_nat_core.h>
|
|
#include <linux/netfilter_ipv4/ip_nat_helper.h>
|
|
#include <linux/netfilter_ipv4/listhelp.h>
|
|
|
|
#if 0
|
|
#define DEBUGP printk
|
|
#define DUMP_OFFSET(x) printk("offset_before=%d, offset_after=%d, correction_pos=%u\n", x->offset_before, x->offset_after, x->correction_pos);
|
|
#else
|
|
#define DEBUGP(format, args...)
|
|
#define DUMP_OFFSET(x)
|
|
#endif
|
|
|
|
static DEFINE_SPINLOCK(ip_nat_seqofs_lock);
|
|
|
|
/* Setup TCP sequence correction given this change at this sequence */
|
|
static inline void
|
|
adjust_tcp_sequence(u32 seq,
|
|
int sizediff,
|
|
struct ip_conntrack *ct,
|
|
enum ip_conntrack_info ctinfo)
|
|
{
|
|
int dir;
|
|
struct ip_nat_seq *this_way, *other_way;
|
|
|
|
DEBUGP("ip_nat_resize_packet: old_size = %u, new_size = %u\n",
|
|
(*skb)->len, new_size);
|
|
|
|
dir = CTINFO2DIR(ctinfo);
|
|
|
|
this_way = &ct->nat.info.seq[dir];
|
|
other_way = &ct->nat.info.seq[!dir];
|
|
|
|
DEBUGP("ip_nat_resize_packet: Seq_offset before: ");
|
|
DUMP_OFFSET(this_way);
|
|
|
|
spin_lock_bh(&ip_nat_seqofs_lock);
|
|
|
|
/* SYN adjust. If it's uninitialized, or this is after last
|
|
* correction, record it: we don't handle more than one
|
|
* adjustment in the window, but do deal with common case of a
|
|
* retransmit */
|
|
if (this_way->offset_before == this_way->offset_after
|
|
|| before(this_way->correction_pos, seq)) {
|
|
this_way->correction_pos = seq;
|
|
this_way->offset_before = this_way->offset_after;
|
|
this_way->offset_after += sizediff;
|
|
}
|
|
spin_unlock_bh(&ip_nat_seqofs_lock);
|
|
|
|
DEBUGP("ip_nat_resize_packet: Seq_offset after: ");
|
|
DUMP_OFFSET(this_way);
|
|
}
|
|
|
|
/* Frobs data inside this packet, which is linear. */
|
|
static void mangle_contents(struct sk_buff *skb,
|
|
unsigned int dataoff,
|
|
unsigned int match_offset,
|
|
unsigned int match_len,
|
|
const char *rep_buffer,
|
|
unsigned int rep_len)
|
|
{
|
|
unsigned char *data;
|
|
|
|
BUG_ON(skb_is_nonlinear(skb));
|
|
data = (unsigned char *)skb->nh.iph + dataoff;
|
|
|
|
/* move post-replacement */
|
|
memmove(data + match_offset + rep_len,
|
|
data + match_offset + match_len,
|
|
skb->tail - (data + match_offset + match_len));
|
|
|
|
/* insert data from buffer */
|
|
memcpy(data + match_offset, rep_buffer, rep_len);
|
|
|
|
/* update skb info */
|
|
if (rep_len > match_len) {
|
|
DEBUGP("ip_nat_mangle_packet: Extending packet by "
|
|
"%u from %u bytes\n", rep_len - match_len,
|
|
skb->len);
|
|
skb_put(skb, rep_len - match_len);
|
|
} else {
|
|
DEBUGP("ip_nat_mangle_packet: Shrinking packet from "
|
|
"%u from %u bytes\n", match_len - rep_len,
|
|
skb->len);
|
|
__skb_trim(skb, skb->len + rep_len - match_len);
|
|
}
|
|
|
|
/* fix IP hdr checksum information */
|
|
skb->nh.iph->tot_len = htons(skb->len);
|
|
ip_send_check(skb->nh.iph);
|
|
}
|
|
|
|
/* Unusual, but possible case. */
|
|
static int enlarge_skb(struct sk_buff **pskb, unsigned int extra)
|
|
{
|
|
struct sk_buff *nskb;
|
|
|
|
if ((*pskb)->len + extra > 65535)
|
|
return 0;
|
|
|
|
nskb = skb_copy_expand(*pskb, skb_headroom(*pskb), extra, GFP_ATOMIC);
|
|
if (!nskb)
|
|
return 0;
|
|
|
|
/* Transfer socket to new skb. */
|
|
if ((*pskb)->sk)
|
|
skb_set_owner_w(nskb, (*pskb)->sk);
|
|
kfree_skb(*pskb);
|
|
*pskb = nskb;
|
|
return 1;
|
|
}
|
|
|
|
/* Generic function for mangling variable-length address changes inside
|
|
* NATed TCP connections (like the PORT XXX,XXX,XXX,XXX,XXX,XXX
|
|
* command in FTP).
|
|
*
|
|
* Takes care about all the nasty sequence number changes, checksumming,
|
|
* skb enlargement, ...
|
|
*
|
|
* */
|
|
int
|
|
ip_nat_mangle_tcp_packet(struct sk_buff **pskb,
|
|
struct ip_conntrack *ct,
|
|
enum ip_conntrack_info ctinfo,
|
|
unsigned int match_offset,
|
|
unsigned int match_len,
|
|
const char *rep_buffer,
|
|
unsigned int rep_len)
|
|
{
|
|
struct iphdr *iph;
|
|
struct tcphdr *tcph;
|
|
int datalen;
|
|
|
|
if (!skb_make_writable(pskb, (*pskb)->len))
|
|
return 0;
|
|
|
|
if (rep_len > match_len
|
|
&& rep_len - match_len > skb_tailroom(*pskb)
|
|
&& !enlarge_skb(pskb, rep_len - match_len))
|
|
return 0;
|
|
|
|
SKB_LINEAR_ASSERT(*pskb);
|
|
|
|
iph = (*pskb)->nh.iph;
|
|
tcph = (void *)iph + iph->ihl*4;
|
|
|
|
mangle_contents(*pskb, iph->ihl*4 + tcph->doff*4,
|
|
match_offset, match_len, rep_buffer, rep_len);
|
|
|
|
datalen = (*pskb)->len - iph->ihl*4;
|
|
tcph->check = 0;
|
|
tcph->check = tcp_v4_check(tcph, datalen, iph->saddr, iph->daddr,
|
|
csum_partial((char *)tcph, datalen, 0));
|
|
|
|
if (rep_len != match_len) {
|
|
set_bit(IPS_SEQ_ADJUST_BIT, &ct->status);
|
|
adjust_tcp_sequence(ntohl(tcph->seq),
|
|
(int)rep_len - (int)match_len,
|
|
ct, ctinfo);
|
|
/* Tell TCP window tracking about seq change */
|
|
ip_conntrack_tcp_update(*pskb, ct, CTINFO2DIR(ctinfo));
|
|
}
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(ip_nat_mangle_tcp_packet);
|
|
|
|
/* Generic function for mangling variable-length address changes inside
|
|
* NATed UDP connections (like the CONNECT DATA XXXXX MESG XXXXX INDEX XXXXX
|
|
* command in the Amanda protocol)
|
|
*
|
|
* Takes care about all the nasty sequence number changes, checksumming,
|
|
* skb enlargement, ...
|
|
*
|
|
* XXX - This function could be merged with ip_nat_mangle_tcp_packet which
|
|
* should be fairly easy to do.
|
|
*/
|
|
int
|
|
ip_nat_mangle_udp_packet(struct sk_buff **pskb,
|
|
struct ip_conntrack *ct,
|
|
enum ip_conntrack_info ctinfo,
|
|
unsigned int match_offset,
|
|
unsigned int match_len,
|
|
const char *rep_buffer,
|
|
unsigned int rep_len)
|
|
{
|
|
struct iphdr *iph;
|
|
struct udphdr *udph;
|
|
|
|
/* UDP helpers might accidentally mangle the wrong packet */
|
|
iph = (*pskb)->nh.iph;
|
|
if ((*pskb)->len < iph->ihl*4 + sizeof(*udph) +
|
|
match_offset + match_len)
|
|
return 0;
|
|
|
|
if (!skb_make_writable(pskb, (*pskb)->len))
|
|
return 0;
|
|
|
|
if (rep_len > match_len
|
|
&& rep_len - match_len > skb_tailroom(*pskb)
|
|
&& !enlarge_skb(pskb, rep_len - match_len))
|
|
return 0;
|
|
|
|
iph = (*pskb)->nh.iph;
|
|
udph = (void *)iph + iph->ihl*4;
|
|
mangle_contents(*pskb, iph->ihl*4 + sizeof(*udph),
|
|
match_offset, match_len, rep_buffer, rep_len);
|
|
|
|
/* update the length of the UDP packet */
|
|
udph->len = htons((*pskb)->len - iph->ihl*4);
|
|
|
|
/* fix udp checksum if udp checksum was previously calculated */
|
|
if (udph->check) {
|
|
int datalen = (*pskb)->len - iph->ihl * 4;
|
|
udph->check = 0;
|
|
udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
|
|
datalen, IPPROTO_UDP,
|
|
csum_partial((char *)udph,
|
|
datalen, 0));
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(ip_nat_mangle_udp_packet);
|
|
|
|
/* Adjust one found SACK option including checksum correction */
|
|
static void
|
|
sack_adjust(struct sk_buff *skb,
|
|
struct tcphdr *tcph,
|
|
unsigned int sackoff,
|
|
unsigned int sackend,
|
|
struct ip_nat_seq *natseq)
|
|
{
|
|
while (sackoff < sackend) {
|
|
struct tcp_sack_block *sack;
|
|
u_int32_t new_start_seq, new_end_seq;
|
|
|
|
sack = (void *)skb->data + sackoff;
|
|
if (after(ntohl(sack->start_seq) - natseq->offset_before,
|
|
natseq->correction_pos))
|
|
new_start_seq = ntohl(sack->start_seq)
|
|
- natseq->offset_after;
|
|
else
|
|
new_start_seq = ntohl(sack->start_seq)
|
|
- natseq->offset_before;
|
|
new_start_seq = htonl(new_start_seq);
|
|
|
|
if (after(ntohl(sack->end_seq) - natseq->offset_before,
|
|
natseq->correction_pos))
|
|
new_end_seq = ntohl(sack->end_seq)
|
|
- natseq->offset_after;
|
|
else
|
|
new_end_seq = ntohl(sack->end_seq)
|
|
- natseq->offset_before;
|
|
new_end_seq = htonl(new_end_seq);
|
|
|
|
DEBUGP("sack_adjust: start_seq: %d->%d, end_seq: %d->%d\n",
|
|
ntohl(sack->start_seq), new_start_seq,
|
|
ntohl(sack->end_seq), new_end_seq);
|
|
|
|
tcph->check =
|
|
ip_nat_cheat_check(~sack->start_seq, new_start_seq,
|
|
ip_nat_cheat_check(~sack->end_seq,
|
|
new_end_seq,
|
|
tcph->check));
|
|
sack->start_seq = new_start_seq;
|
|
sack->end_seq = new_end_seq;
|
|
sackoff += sizeof(*sack);
|
|
}
|
|
}
|
|
|
|
/* TCP SACK sequence number adjustment */
|
|
static inline unsigned int
|
|
ip_nat_sack_adjust(struct sk_buff **pskb,
|
|
struct tcphdr *tcph,
|
|
struct ip_conntrack *ct,
|
|
enum ip_conntrack_info ctinfo)
|
|
{
|
|
unsigned int dir, optoff, optend;
|
|
|
|
optoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct tcphdr);
|
|
optend = (*pskb)->nh.iph->ihl*4 + tcph->doff*4;
|
|
|
|
if (!skb_make_writable(pskb, optend))
|
|
return 0;
|
|
|
|
dir = CTINFO2DIR(ctinfo);
|
|
|
|
while (optoff < optend) {
|
|
/* Usually: option, length. */
|
|
unsigned char *op = (*pskb)->data + optoff;
|
|
|
|
switch (op[0]) {
|
|
case TCPOPT_EOL:
|
|
return 1;
|
|
case TCPOPT_NOP:
|
|
optoff++;
|
|
continue;
|
|
default:
|
|
/* no partial options */
|
|
if (optoff + 1 == optend
|
|
|| optoff + op[1] > optend
|
|
|| op[1] < 2)
|
|
return 0;
|
|
if (op[0] == TCPOPT_SACK
|
|
&& op[1] >= 2+TCPOLEN_SACK_PERBLOCK
|
|
&& ((op[1] - 2) % TCPOLEN_SACK_PERBLOCK) == 0)
|
|
sack_adjust(*pskb, tcph, optoff+2,
|
|
optoff+op[1],
|
|
&ct->nat.info.seq[!dir]);
|
|
optoff += op[1];
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/* TCP sequence number adjustment. Returns 1 on success, 0 on failure */
|
|
int
|
|
ip_nat_seq_adjust(struct sk_buff **pskb,
|
|
struct ip_conntrack *ct,
|
|
enum ip_conntrack_info ctinfo)
|
|
{
|
|
struct tcphdr *tcph;
|
|
int dir, newseq, newack;
|
|
struct ip_nat_seq *this_way, *other_way;
|
|
|
|
dir = CTINFO2DIR(ctinfo);
|
|
|
|
this_way = &ct->nat.info.seq[dir];
|
|
other_way = &ct->nat.info.seq[!dir];
|
|
|
|
if (!skb_make_writable(pskb, (*pskb)->nh.iph->ihl*4+sizeof(*tcph)))
|
|
return 0;
|
|
|
|
tcph = (void *)(*pskb)->data + (*pskb)->nh.iph->ihl*4;
|
|
if (after(ntohl(tcph->seq), this_way->correction_pos))
|
|
newseq = ntohl(tcph->seq) + this_way->offset_after;
|
|
else
|
|
newseq = ntohl(tcph->seq) + this_way->offset_before;
|
|
newseq = htonl(newseq);
|
|
|
|
if (after(ntohl(tcph->ack_seq) - other_way->offset_before,
|
|
other_way->correction_pos))
|
|
newack = ntohl(tcph->ack_seq) - other_way->offset_after;
|
|
else
|
|
newack = ntohl(tcph->ack_seq) - other_way->offset_before;
|
|
newack = htonl(newack);
|
|
|
|
tcph->check = ip_nat_cheat_check(~tcph->seq, newseq,
|
|
ip_nat_cheat_check(~tcph->ack_seq,
|
|
newack,
|
|
tcph->check));
|
|
|
|
DEBUGP("Adjusting sequence number from %u->%u, ack from %u->%u\n",
|
|
ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq),
|
|
ntohl(newack));
|
|
|
|
tcph->seq = newseq;
|
|
tcph->ack_seq = newack;
|
|
|
|
if (!ip_nat_sack_adjust(pskb, tcph, ct, ctinfo))
|
|
return 0;
|
|
|
|
ip_conntrack_tcp_update(*pskb, ct, dir);
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(ip_nat_seq_adjust);
|
|
|
|
/* Setup NAT on this expected conntrack so it follows master. */
|
|
/* If we fail to get a free NAT slot, we'll get dropped on confirm */
|
|
void ip_nat_follow_master(struct ip_conntrack *ct,
|
|
struct ip_conntrack_expect *exp)
|
|
{
|
|
struct ip_nat_range range;
|
|
|
|
/* This must be a fresh one. */
|
|
BUG_ON(ct->status & IPS_NAT_DONE_MASK);
|
|
|
|
/* Change src to where master sends to */
|
|
range.flags = IP_NAT_RANGE_MAP_IPS;
|
|
range.min_ip = range.max_ip
|
|
= ct->master->tuplehash[!exp->dir].tuple.dst.ip;
|
|
/* hook doesn't matter, but it has to do source manip */
|
|
ip_nat_setup_info(ct, &range, NF_IP_POST_ROUTING);
|
|
|
|
/* For DST manip, map port here to where it's expected. */
|
|
range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
|
|
range.min = range.max = exp->saved_proto;
|
|
range.min_ip = range.max_ip
|
|
= ct->master->tuplehash[!exp->dir].tuple.src.ip;
|
|
/* hook doesn't matter, but it has to do destination manip */
|
|
ip_nat_setup_info(ct, &range, NF_IP_PRE_ROUTING);
|
|
}
|
|
EXPORT_SYMBOL(ip_nat_follow_master);
|