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NetBSD/sys/netinet/ip_proxy.c
bouyer 4f806e660f Fix for kern/7831 from Darren Reed after discussion on tech-net 2 weeks ago: 
check that the packet if of the rigth protocol before giving it to the
proxy module, otherwise let the ipnat code handle it.
What happens in kern/7831 is that a router sends back a icmp message for
a TCP SYN, and ip_proxy.c forwards it to ip_ftp_pxy.c which can only
handle TCP packets. The icmp message is properly handled by ipnat, no need to
go to ip_ftp_pxy.c.
1999-08-24 16:10:35 +00:00

401 lines
8.4 KiB
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/* $NetBSD: ip_proxy.c,v 1.18 1999/08/24 16:10:35 bouyer Exp $ */
/*
* Copyright (C) 1997-1998 by Darren Reed.
*
* Redistribution and use in source and binary forms are permitted
* provided that this notice is preserved and due credit is given
* to the original author and the contributors.
*/
#if !defined(lint)
#if defined(__NetBSD__)
static const char rcsid[] = "$NetBSD: ip_proxy.c,v 1.18 1999/08/24 16:10:35 bouyer Exp $";
#else
static const char rcsid[] = "@(#)Id: ip_proxy.c,v 2.0.2.11.2.15 1998/11/22 01:50:29 darrenr Exp ";
#endif
#endif
#if defined(__FreeBSD__) && defined(KERNEL) && !defined(_KERNEL)
# define _KERNEL
#endif
#include <sys/errno.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <sys/uio.h>
#if !defined(_KERNEL) && !defined(KERNEL)
# include <stdio.h>
# include <string.h>
# include <stdlib.h>
#endif
#ifndef linux
# include <sys/protosw.h>
#endif
#include <sys/socket.h>
#if defined(_KERNEL)
# if !defined(linux)
# include <sys/systm.h>
# else
# include <linux/string.h>
# endif
#endif
#if !defined(__SVR4) && !defined(__svr4__)
# ifndef linux
# include <sys/mbuf.h>
# endif
#else
# include <sys/byteorder.h>
# include <sys/dditypes.h>
# include <sys/stream.h>
# include <sys/kmem.h>
#endif
#if __FreeBSD__ > 2
# include <sys/queue.h>
#endif
#include <net/if.h>
#ifdef sun
# include <net/af.h>
#endif
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#ifndef linux
# include <netinet/ip_var.h>
#endif
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/ip_icmp.h>
#include "netinet/ip_compat.h"
#include <netinet/tcpip.h>
#include "netinet/ip_fil.h"
#include "netinet/ip_proxy.h"
#include "netinet/ip_nat.h"
#include "netinet/ip_state.h"
#ifndef MIN
#define MIN(a,b) (((a)<(b))?(a):(b))
#endif
static ap_session_t *ap_new_session __P((aproxy_t *, ip_t *,
fr_info_t *, nat_t *));
int ap_fixseqack __P((fr_info_t *, ip_t *, ap_session_t *, int inc));
#define AP_SESS_SIZE 53
#if defined(_KERNEL) && !defined(linux)
#include "netinet/ip_ftp_pxy.c"
#endif
ap_session_t *ap_sess_tab[AP_SESS_SIZE];
ap_session_t *ap_sess_list = NULL;
aproxy_t ap_proxies[] = {
#ifdef IPF_FTP_PROXY
{ "ftp", (char)IPPROTO_TCP, 0, 0, ippr_ftp_init, ippr_ftp_in, ippr_ftp_out },
#endif
{ "", '\0', 0, 0, NULL, NULL }
};
int ap_ok(ip, tcp, nat)
ip_t *ip;
tcphdr_t *tcp;
ipnat_t *nat;
{
aproxy_t *apr = nat->in_apr;
u_short dport = nat->in_dport;
if (!apr || (apr && (apr->apr_flags & APR_DELETE)) ||
(ip->ip_p != apr->apr_p))
return 0;
if ((tcp && (tcp->th_dport != dport)) || (!tcp && dport))
return 0;
return 1;
}
/*
* Allocate a new application proxy structure and fill it in with the
* relevant details. call the init function once complete, prior to
* returning.
*/
static ap_session_t *ap_new_session(apr, ip, fin, nat)
aproxy_t *apr;
ip_t *ip;
fr_info_t *fin;
nat_t *nat;
{
register ap_session_t *aps;
tcphdr_t *tcp;
u_short dport;
u_int hv;
if (!apr || (apr && (apr->apr_flags & APR_DELETE)) ||
(ip->ip_p != apr->apr_p))
return NULL;
if (!(fin->fin_fi.fi_fl & FI_TCPUDP))
tcp = NULL;
else
tcp = (tcphdr_t *)fin->fin_dp;
dport = nat->nat_ptr->in_dport;
if ((tcp && (tcp->th_dport != dport)) || (!tcp && dport))
return NULL;
hv = ip->ip_src.s_addr ^ ip->ip_dst.s_addr;
hv *= 651733;
if (tcp) {
hv ^= (tcp->th_sport + tcp->th_dport);
hv *= 5;
}
hv %= AP_SESS_SIZE;
KMALLOC(aps, ap_session_t *, sizeof(*aps));
if (!aps)
return NULL;
bzero((char *)aps, sizeof(*aps));
aps->aps_apr = apr;
aps->aps_src = ip->ip_src;
aps->aps_dst = ip->ip_dst;
aps->aps_p = ip->ip_p;
if (tcp) {
aps->aps_sport = tcp->th_sport;
aps->aps_dport = tcp->th_dport;
}
aps->aps_data = NULL;
aps->aps_psiz = 0;
aps->aps_hnext = ap_sess_tab[hv];
aps->aps_next = ap_sess_list;
ap_sess_list = aps;
aps->aps_nat = nat;
aps->aps_hv = hv;
nat->nat_aps = aps;
ap_sess_tab[hv] = aps;
(void) (*apr->apr_init)(fin, ip, aps, nat);
return aps;
}
/*
* check to see if a packet should be passed through an active proxy routine
* if one has been setup for it.
*/
int ap_check(ip, fin, nat)
ip_t *ip;
fr_info_t *fin;
nat_t *nat;
{
ap_session_t *aps;
aproxy_t *apr;
tcphdr_t *tcp = NULL;
u_32_t sum;
int err;
if ((aps = nat->nat_aps) == NULL)
aps = ap_new_session(nat->nat_ptr->in_apr, ip, fin, nat);
if ((aps != NULL) && (aps->aps_p == ip->ip_p)) {
if (ip->ip_p == IPPROTO_TCP) {
tcp = (tcphdr_t *)fin->fin_dp;
/*
* verify that the checksum is correct. If not, then
* don't do anything with this packet.
*/
#if SOLARIS && defined(_KERNEL)
sum = fr_tcpsum(fin->fin_qfm, ip, tcp, ip->ip_len);
#else
sum = fr_tcpsum(*(mb_t **)fin->fin_mp,
ip, tcp, ip->ip_len);
#endif
if (sum != 0) {
frstats[fin->fin_out].fr_tcpbad++;
return -1;
}
}
apr = aps->aps_apr;
err = 0;
if (fin->fin_out) {
if (apr->apr_outpkt)
err = (*apr->apr_outpkt)(fin, ip, aps, nat);
} else {
if (apr->apr_inpkt)
err = (*apr->apr_inpkt)(fin, ip, aps, nat);
}
if (tcp != NULL) {
err = ap_fixseqack(fin, ip, aps, err);
tcp->th_sum = 0;
#if SOLARIS && defined(_KERNEL)
tcp->th_sum = fr_tcpsum(fin->fin_qfm, ip, tcp,
ip->ip_len);
#else
tcp->th_sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip,
tcp, ip->ip_len);
#endif
}
aps->aps_bytes += ip->ip_len;
aps->aps_pkts++;
return 2;
}
return -1;
}
aproxy_t *ap_match(pr, name)
u_char pr;
char *name;
{
aproxy_t *ap;
for (ap = ap_proxies; ap->apr_p; ap++)
if ((ap->apr_p == pr) &&
!strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
ap->apr_ref++;
return ap;
}
return NULL;
}
void ap_free(ap)
aproxy_t *ap;
{
ap->apr_ref--;
}
void aps_free(aps)
ap_session_t *aps;
{
ap_session_t *a, **ap;
u_int hv;
if (!aps)
return;
hv = aps->aps_hv;
for (ap = ap_sess_tab + hv; (a = *ap); ap = &a->aps_hnext)
if (a == aps) {
*ap = a->aps_hnext;
break;
}
for (ap = &ap_sess_list; (a = *ap); ap = &a->aps_next)
if (a == aps) {
*ap = a->aps_next;
break;
}
if (a) {
if (aps->aps_data && aps->aps_psiz)
KFREES(aps->aps_data, aps->aps_psiz);
KFREE(aps);
}
}
int ap_fixseqack(fin, ip, aps, inc)
fr_info_t *fin;
ip_t *ip;
ap_session_t *aps;
int inc;
{
int sel, ch = 0, out, nlen;
u_32_t seq1, seq2;
tcphdr_t *tcp;
tcp = (tcphdr_t *)fin->fin_dp;
out = fin->fin_out;
nlen = ip->ip_len;
nlen -= (ip->ip_hl << 2) + (tcp->th_off << 2);
if (out != 0) {
seq1 = (u_32_t)ntohl(tcp->th_seq);
sel = aps->aps_sel[out];
/* switch to other set ? */
if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
(seq1 > aps->aps_seqmin[!sel]))
sel = aps->aps_sel[out] = !sel;
if (aps->aps_seqoff[sel]) {
seq2 = aps->aps_seqmin[sel] - aps->aps_seqoff[sel];
if (seq1 > seq2) {
seq2 = aps->aps_seqoff[sel];
seq1 += seq2;
tcp->th_seq = htonl(seq1);
ch = 1;
}
}
if (inc && (seq1 > aps->aps_seqmin[!sel])) {
aps->aps_seqmin[!sel] = seq1 + nlen - 1;
aps->aps_seqoff[!sel] = aps->aps_seqoff[sel] + inc;
}
/***/
seq1 = ntohl(tcp->th_ack);
sel = aps->aps_sel[1 - out];
/* switch to other set ? */
if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
(seq1 > aps->aps_ackmin[!sel]))
sel = aps->aps_sel[1 - out] = !sel;
if (aps->aps_ackoff[sel] && (seq1 > aps->aps_ackmin[sel])) {
seq2 = aps->aps_ackoff[sel];
tcp->th_ack = htonl(seq1 - seq2);
ch = 1;
}
} else {
seq1 = ntohl(tcp->th_seq);
sel = aps->aps_sel[out];
/* switch to other set ? */
if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
(seq1 > aps->aps_ackmin[!sel]))
sel = aps->aps_sel[out] = !sel;
if (aps->aps_ackoff[sel]) {
seq2 = aps->aps_ackmin[sel] -
aps->aps_ackoff[sel];
if (seq1 > seq2) {
seq2 = aps->aps_ackoff[sel];
seq1 += seq2;
tcp->th_seq = htonl(seq1);
ch = 1;
}
}
if (inc && (seq1 > aps->aps_ackmin[!sel])) {
aps->aps_ackmin[!sel] = seq1 + nlen - 1;
aps->aps_ackoff[!sel] = aps->aps_ackoff[sel] + inc;
}
/***/
seq1 = ntohl(tcp->th_ack);
sel = aps->aps_sel[1 - out];
/* switch to other set ? */
if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
(seq1 > aps->aps_seqmin[!sel]))
sel = aps->aps_sel[1 - out] = !sel;
if (aps->aps_seqoff[sel] && (seq1 > aps->aps_seqmin[sel])) {
seq2 = aps->aps_seqoff[sel];
tcp->th_ack = htonl(seq1 - seq2);
ch = 1;
}
}
return ch ? 2 : 0;
}
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