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freebsd/sys/netinet/ip_state.c

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/*
* Copyright (C) 1995-1998 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)
static const char sccsid[] = "@(#)ip_state.c 1.8 6/5/96 (C) 1993-1995 Darren Reed";
/*static const char rcsid[] = "@(#)$Id: ip_state.c,v 2.3.2.16 1999/12/28 05:24:58 darrenr Exp $";*/
static const char rcsid[] = "@(#)$FreeBSD$";
#endif
#include <sys/errno.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/file.h>
#if defined(__NetBSD__) && (NetBSD >= 199905) && !defined(IPFILTER_LKM) && \
defined(_KERNEL)
# include "opt_ipfilter_log.h"
#endif
#if !defined(_KERNEL) && !defined(KERNEL) && !defined(__KERNEL__)
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
#else
# ifdef linux
# include <linux/kernel.h>
# include <linux/module.h>
# endif
#endif
#if ((defined(KERNEL) && (__FreeBSD_version >= 220000)) || \
(defined(_KERNEL) && (__FreeBSD_version >= 400013)))
# include <sys/filio.h>
# include <sys/fcntl.h>
# if (__FreeBSD_version >= 300000) && !defined(IPFILTER_LKM)
# include "opt_ipfilter.h"
# endif
#else
# include <sys/ioctl.h>
#endif
#include <sys/time.h>
#include <sys/uio.h>
#ifndef linux
# include <sys/protosw.h>
#endif
#include <sys/socket.h>
#if defined(_KERNEL) && !defined(linux)
# include <sys/systm.h>
#endif
#if !defined(__SVR4) && !defined(__svr4__)
# ifndef linux
# include <sys/mbuf.h>
# endif
#else
# include <sys/filio.h>
# include <sys/byteorder.h>
# ifdef _KERNEL
# include <sys/dditypes.h>
# endif
# include <sys/stream.h>
# include <sys/kmem.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>
#include <netinet/tcp.h>
#ifndef linux
# include <netinet/ip_var.h>
# include <netinet/tcp_fsm.h>
#endif
#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_nat.h"
#include "netinet/ip_frag.h"
#include "netinet/ip_proxy.h"
#include "netinet/ip_state.h"
#if (__FreeBSD_version >= 300000)
# include <sys/malloc.h>
# if (defined(_KERNEL) || defined(KERNEL)) && !defined(IPFILTER_LKM)
# include <sys/libkern.h>
# include <sys/systm.h>
# endif
#endif
#ifndef MIN
# define MIN(a,b) (((a)<(b))?(a):(b))
#endif
#define TCP_CLOSE (TH_FIN|TH_RST)
ipstate_t **ips_table = NULL;
int ips_num = 0;
ips_stat_t ips_stats;
#if (SOLARIS || defined(__sgi)) && defined(_KERNEL)
extern KRWLOCK_T ipf_state, ipf_mutex;
extern kmutex_t ipf_rw;
#endif
static int fr_matchsrcdst __P((ipstate_t *, struct in_addr, struct in_addr,
fr_info_t *, tcphdr_t *));
static frentry_t *fr_checkicmpmatchingstate __P((ip_t *, fr_info_t *));
static int fr_state_flush __P((int));
static ips_stat_t *fr_statetstats __P((void));
static void fr_delstate __P((ipstate_t *));
#define FIVE_DAYS (2 * 5 * 86400) /* 5 days: half closed session */
#define TCP_MSL 240 /* 2 minutes */
u_long fr_tcpidletimeout = FIVE_DAYS,
fr_tcpclosewait = 2 * TCP_MSL,
fr_tcplastack = 2 * TCP_MSL,
fr_tcptimeout = 2 * TCP_MSL,
fr_tcpclosed = 1,
fr_udptimeout = 240,
fr_icmptimeout = 120;
int fr_statemax = IPSTATE_MAX,
fr_statesize = IPSTATE_SIZE;
int fr_state_doflush = 0;
int fr_stateinit()
{
KMALLOCS(ips_table, ipstate_t **, fr_statesize * sizeof(ipstate_t *));
if (ips_table != NULL)
bzero((char *)ips_table, fr_statesize * sizeof(ipstate_t *));
else
return -1;
return 0;
}
static ips_stat_t *fr_statetstats()
{
ips_stats.iss_active = ips_num;
ips_stats.iss_table = ips_table;
return &ips_stats;
}
/*
* flush state tables. two actions currently defined:
* which == 0 : flush all state table entries
* which == 1 : flush TCP connections which have started to close but are
* stuck for some reason.
*/
static int fr_state_flush(which)
int which;
{
register int i;
register ipstate_t *is, **isp;
#if defined(_KERNEL) && !SOLARIS
int s;
#endif
int delete, removed = 0;
SPL_NET(s);
WRITE_ENTER(&ipf_state);
for (i = fr_statesize - 1; i >= 0; i--)
for (isp = &ips_table[i]; (is = *isp); ) {
delete = 0;
switch (which)
{
case 0 :
delete = 1;
break;
case 1 :
if ((is->is_p == IPPROTO_TCP) &&
(((is->is_state[0] <= TCPS_ESTABLISHED) &&
(is->is_state[1] > TCPS_ESTABLISHED)) ||
((is->is_state[1] <= TCPS_ESTABLISHED) &&
(is->is_state[0] > TCPS_ESTABLISHED))))
delete = 1;
break;
}
if (delete) {
*isp = is->is_next;
if (is->is_p == IPPROTO_TCP)
ips_stats.iss_fin++;
else
ips_stats.iss_expire++;
if (ips_table[i] == NULL)
ips_stats.iss_inuse--;
#ifdef IPFILTER_LOG
ipstate_log(is, ISL_FLUSH);
#endif
fr_delstate(is);
ips_num--;
removed++;
} else
isp = &is->is_next;
}
RWLOCK_EXIT(&ipf_state);
SPL_X(s);
return removed;
}
int fr_state_ioctl(data, cmd, mode)
caddr_t data;
#if defined(__NetBSD__) || defined(__OpenBSD__)
u_long cmd;
#else
int cmd;
#endif
int mode;
{
int arg, ret, error = 0;
switch (cmd)
{
case SIOCIPFFL :
IRCOPY(data, (caddr_t)&arg, sizeof(arg));
if (arg == 0 || arg == 1) {
ret = fr_state_flush(arg);
IWCOPY((caddr_t)&ret, data, sizeof(ret));
} else
error = EINVAL;
break;
#ifdef IPFILTER_LOG
case SIOCIPFFB :
if (!(mode & FWRITE))
error = EPERM;
else
*(int *)data = ipflog_clear(IPL_LOGSTATE);
break;
#endif
case SIOCGIPST :
IWCOPY((caddr_t)fr_statetstats(), data, sizeof(ips_stat_t));
break;
case FIONREAD :
#ifdef IPFILTER_LOG
IWCOPY((caddr_t)&iplused[IPL_LOGSTATE], (caddr_t)data,
sizeof(iplused[IPL_LOGSTATE]));
#endif
break;
default :
error = EINVAL;
break;
}
return error;
}
/*
* Create a new ipstate structure and hang it off the hash table.
*/
ipstate_t *fr_addstate(ip, fin, flags)
ip_t *ip;
fr_info_t *fin;
u_int flags;
{
register ipstate_t *is;
register u_int hv;
ipstate_t ips;
u_int pass;
if ((ip->ip_off & IP_OFFMASK) || (fin->fin_fi.fi_fl & FI_SHORT))
return NULL;
if (ips_num == fr_statemax) {
ips_stats.iss_max++;
fr_state_doflush = 1;
return NULL;
}
is = &ips;
bzero((char *)is, sizeof(*is));
ips.is_age = 1;
ips.is_state[0] = 0;
ips.is_state[1] = 0;
/*
* Copy and calculate...
*/
hv = (is->is_p = ip->ip_p);
hv += (is->is_src.s_addr = ip->ip_src.s_addr);
hv += (is->is_dst.s_addr = ip->ip_dst.s_addr);
switch (ip->ip_p)
{
case IPPROTO_ICMP :
{
struct icmp *ic = (struct icmp *)fin->fin_dp;
switch (ic->icmp_type)
{
case ICMP_ECHO :
is->is_icmp.ics_type = ICMP_ECHOREPLY; /* XXX */
hv += (is->is_icmp.ics_id = ic->icmp_id);
hv += (is->is_icmp.ics_seq = ic->icmp_seq);
break;
case ICMP_TSTAMP :
case ICMP_IREQ :
case ICMP_MASKREQ :
is->is_icmp.ics_type = ic->icmp_type + 1;
break;
default :
return NULL;
}
ATOMIC_INC(ips_stats.iss_icmp);
is->is_age = fr_icmptimeout;
break;
}
case IPPROTO_TCP :
{
register tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
/*
* The endian of the ports doesn't matter, but the ack and
* sequence numbers do as we do mathematics on them later.
*/
is->is_dport = tcp->th_dport;
is->is_sport = tcp->th_sport;
if ((flags & (FI_W_DPORT|FI_W_SPORT)) == 0) {
hv += tcp->th_dport;
hv += tcp->th_sport;
}
if (tcp->th_seq != 0) {
is->is_send = ntohl(tcp->th_seq) + ip->ip_len -
fin->fin_hlen - (tcp->th_off << 2) +
((tcp->th_flags & TH_SYN) ? 1 : 0) +
((tcp->th_flags & TH_FIN) ? 1 : 0);
is->is_maxsend = is->is_send + 1;
}
is->is_dend = 0;
is->is_maxswin = ntohs(tcp->th_win);
if (is->is_maxswin == 0)
is->is_maxswin = 1;
/*
* If we're creating state for a starting connection, start the
* timer on it as we'll never see an error if it fails to
* connect.
*/
MUTEX_ENTER(&ipf_rw);
ips_stats.iss_tcp++;
fr_tcp_age(&is->is_age, is->is_state, ip, fin,
tcp->th_sport == is->is_sport);
MUTEX_EXIT(&ipf_rw);
break;
}
case IPPROTO_UDP :
{
register tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
is->is_dport = tcp->th_dport;
is->is_sport = tcp->th_sport;
if ((flags & (FI_W_DPORT|FI_W_SPORT)) == 0) {
hv += tcp->th_dport;
hv += tcp->th_sport;
}
ATOMIC_INC(ips_stats.iss_udp);
is->is_age = fr_udptimeout;
break;
}
default :
return NULL;
}
KMALLOC(is, ipstate_t *);
if (is == NULL) {
ATOMIC_INC(ips_stats.iss_nomem);
return NULL;
}
bcopy((char *)&ips, (char *)is, sizeof(*is));
hv %= fr_statesize;
RW_UPGRADE(&ipf_mutex);
is->is_rule = fin->fin_fr;
if (is->is_rule != NULL) {
is->is_rule->fr_ref++;
pass = is->is_rule->fr_flags;
} else
pass = fr_flags;
MUTEX_DOWNGRADE(&ipf_mutex);
WRITE_ENTER(&ipf_state);
is->is_rout = pass & FR_OUTQUE ? 1 : 0;
is->is_pass = pass;
is->is_pkts = 1;
is->is_bytes = ip->ip_len;
/*
* We want to check everything that is a property of this packet,
* but we don't (automatically) care about it's fragment status as
* this may change.
*/
is->is_opt = fin->fin_fi.fi_optmsk;
is->is_optmsk = 0xffffffff;
is->is_sec = fin->fin_fi.fi_secmsk;
is->is_secmsk = 0xffff;
is->is_auth = fin->fin_fi.fi_auth;
is->is_authmsk = 0xffff;
is->is_flags = fin->fin_fi.fi_fl & FI_CMP;
is->is_flags |= FI_CMP << 4;
is->is_flags |= flags & (FI_W_DPORT|FI_W_SPORT);
/*
* add into table.
*/
is->is_next = ips_table[hv];
ips_table[hv] = is;
if (is->is_next == NULL)
ips_stats.iss_inuse++;
if (fin->fin_out) {
is->is_ifpin = NULL;
is->is_ifpout = fin->fin_ifp;
} else {
is->is_ifpin = fin->fin_ifp;
is->is_ifpout = NULL;
}
if (pass & FR_LOGFIRST)
is->is_pass &= ~(FR_LOGFIRST|FR_LOG);
ATOMIC_INC(ips_num);
#ifdef IPFILTER_LOG
ipstate_log(is, ISL_NEW);
#endif
RWLOCK_EXIT(&ipf_state);
fin->fin_rev = (is->is_dst.s_addr != ip->ip_dst.s_addr);
if (fin->fin_fi.fi_fl & FI_FRAG)
ipfr_newfrag(ip, fin, pass ^ FR_KEEPSTATE);
return is;
}
/*
* check to see if a packet with TCP headers fits within the TCP window.
* change timeout depending on whether new packet is a SYN-ACK returning for a
* SYN or a RST or FIN which indicate time to close up shop.
*/
int fr_tcpstate(is, fin, ip, tcp)
register ipstate_t *is;
fr_info_t *fin;
ip_t *ip;
tcphdr_t *tcp;
{
register tcp_seq seq, ack, end;
register int ackskew;
tcpdata_t *fdata, *tdata;
u_short win, maxwin;
int ret = 0;
int source;
/*
* Find difference between last checked packet and this packet.
*/
source = (ip->ip_src.s_addr == is->is_src.s_addr);
fdata = &is->is_tcp.ts_data[!source];
tdata = &is->is_tcp.ts_data[source];
seq = ntohl(tcp->th_seq);
ack = ntohl(tcp->th_ack);
win = ntohs(tcp->th_win);
end = seq + ip->ip_len - fin->fin_hlen - (tcp->th_off << 2) +
((tcp->th_flags & TH_SYN) ? 1 : 0) +
((tcp->th_flags & TH_FIN) ? 1 : 0);
if (fdata->td_end == 0) {
/*
* Must be a (outgoing) SYN-ACK in reply to a SYN.
*/
fdata->td_end = end;
fdata->td_maxwin = 1;
fdata->td_maxend = end + 1;
}
if (!(tcp->th_flags & TH_ACK)) { /* Pretend an ack was sent */
ack = tdata->td_end;
win = 1;
} else if (((tcp->th_flags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) &&
(ack == 0)) {
/* gross hack to get around certain broken tcp stacks */
ack = tdata->td_end;
}
if (seq == end)
seq = end = fdata->td_end;
maxwin = tdata->td_maxwin;
ackskew = tdata->td_end - ack;
#define SEQ_GE(a,b) ((int)((a) - (b)) >= 0)
#define SEQ_GT(a,b) ((int)((a) - (b)) > 0)
if ((SEQ_GE(fdata->td_maxend, end)) &&
(SEQ_GE(seq + maxwin, fdata->td_end - maxwin)) &&
/* XXX what about big packets */
#define MAXACKWINDOW 66000
(ackskew >= -MAXACKWINDOW) &&
(ackskew <= MAXACKWINDOW)) {
/* if ackskew < 0 then this should be due to fragented
* packets. There is no way to know the length of the
* total packet in advance.
* We do know the total length from the fragment cache though.
* Note however that there might be more sessions with
* exactly the same source and destination paramters in the
* state cache (and source and destination is the only stuff
* that is saved in the fragment cache). Note further that
* some TCP connections in the state cache are hashed with
* sport and dport as well which makes it not worthwhile to
* look for them.
* Thus, when ackskew is negative but still seems to belong
* to this session, we bump up the destinations end value.
*/
if (ackskew < 0)
tdata->td_end = ack;
/* update max window seen */
if (fdata->td_maxwin < win)
fdata->td_maxwin = win;
if (SEQ_GT(end, fdata->td_end))
fdata->td_end = end;
if (SEQ_GE(ack + win, tdata->td_maxend)) {
tdata->td_maxend = ack + win;
if (win == 0)
tdata->td_maxend++;
}
ATOMIC_INC(ips_stats.iss_hits);
is->is_pkts++;
is->is_bytes += ip->ip_len;
/*
* Nearing end of connection, start timeout.
*/
MUTEX_ENTER(&ipf_rw);
fr_tcp_age(&is->is_age, is->is_state, ip, fin, source);
MUTEX_EXIT(&ipf_rw);
ret = 1;
}
return ret;
}
static int fr_matchsrcdst(is, src, dst, fin, tcp)
ipstate_t *is;
struct in_addr src, dst;
fr_info_t *fin;
tcphdr_t *tcp;
{
int ret = 0, rev, out, flags;
u_short sp, dp;
void *ifp;
rev = fin->fin_rev = (is->is_dst.s_addr != dst.s_addr);
ifp = fin->fin_ifp;
out = fin->fin_out;
if (tcp != NULL) {
flags = is->is_flags;
sp = tcp->th_sport;
dp = tcp->th_dport;
} else {
flags = 0;
sp = 0;
dp = 0;
}
if (rev == 0) {
if (!out) {
if (is->is_ifpin == ifp)
ret = 1;
} else {
if (is->is_ifpout == NULL || is->is_ifpout == ifp)
ret = 1;
}
} else {
if (out) {
if (is->is_ifpin == ifp)
ret = 1;
} else {
if (is->is_ifpout == NULL || is->is_ifpout == ifp)
ret = 1;
}
}
if (ret == 0)
return 0;
ret = 0;
if (rev == 0) {
if ((is->is_dst.s_addr == dst.s_addr) &&
(is->is_src.s_addr == src.s_addr) &&
(!tcp || ((sp == is->is_sport || flags & FI_W_SPORT) &&
(dp == is->is_dport || flags & FI_W_DPORT)))) {
ret = 1;
}
} else {
if ((is->is_dst.s_addr == src.s_addr) &&
(is->is_src.s_addr == dst.s_addr) &&
(!tcp || ((sp == is->is_dport || flags & FI_W_DPORT) &&
(dp == is->is_sport || flags & FI_W_SPORT)))) {
ret = 1;
}
}
if (ret == 0)
return 0;
/*
* Whether or not this should be here, is questionable, but the aim
* is to get this out of the main line.
*/
if (tcp == NULL)
flags = is->is_flags & (FI_CMP|(FI_CMP<<4));
if (((fin->fin_fi.fi_fl & (flags >> 4)) != (flags & FI_CMP)) ||
((fin->fin_fi.fi_optmsk & is->is_optmsk) != is->is_opt) ||
((fin->fin_fi.fi_secmsk & is->is_secmsk) != is->is_sec) ||
((fin->fin_fi.fi_auth & is->is_authmsk) != is->is_auth))
return 0;
if ((flags & (FI_W_SPORT|FI_W_DPORT))) {
if ((flags & FI_W_SPORT) != 0) {
if (rev == 0) {
is->is_sport = sp;
is->is_send = htonl(tcp->th_seq);
} else {
is->is_sport = dp;
is->is_send = htonl(tcp->th_ack);
}
is->is_maxsend = is->is_send + 1;
} else if ((flags & FI_W_DPORT) != 0) {
if (rev == 0) {
is->is_dport = dp;
is->is_dend = htonl(tcp->th_ack);
} else {
is->is_dport = sp;
is->is_dend = htonl(tcp->th_seq);
}
is->is_maxdend = is->is_dend + 1;
}
is->is_flags &= ~(FI_W_SPORT|FI_W_DPORT);
}
if (!rev) {
if (out && (out == is->is_rout)) {
if (!is->is_ifpout)
is->is_ifpout = ifp;
} else {
if (!is->is_ifpin)
is->is_ifpin = ifp;
}
} else {
if (!out && (out != is->is_rout)) {
if (!is->is_ifpin)
is->is_ifpin = ifp;
} else {
if (!is->is_ifpout)
is->is_ifpout = ifp;
}
}
return 1;
}
frentry_t *fr_checkicmpmatchingstate(ip, fin)
ip_t *ip;
fr_info_t *fin;
{
register struct in_addr dst, src;
register ipstate_t *is, **isp;
register u_short sport, dport;
register u_char pr;
struct icmp *ic;
u_short savelen;
fr_info_t ofin;
tcphdr_t *tcp;
icmphdr_t *icmp;
frentry_t *fr;
ip_t *oip;
int type;
u_int hv;
/*
* Does it at least have the return (basic) IP header ?
* Only a basic IP header (no options) should be with
* an ICMP error header.
*/
if ((ip->ip_hl != 5) || (ip->ip_len < ICMPERR_MINPKTLEN))
return NULL;
ic = (struct icmp *)((char *)ip + fin->fin_hlen);
type = ic->icmp_type;
/*
* If it's not an error type, then return
*/
if ((type != ICMP_UNREACH) && (type != ICMP_SOURCEQUENCH) &&
(type != ICMP_REDIRECT) && (type != ICMP_TIMXCEED) &&
(type != ICMP_PARAMPROB))
return NULL;
oip = (ip_t *)((char *)fin->fin_dp + ICMPERR_ICMPHLEN);
if (ip->ip_len < ICMPERR_MAXPKTLEN + ((oip->ip_hl - 5) << 2))
return NULL;
if (oip->ip_p == IPPROTO_ICMP) {
icmp = (icmphdr_t *)((char *)oip + (oip->ip_hl << 2));
/*
* a ICMP error can only be generated as a result of an
* ICMP query, not as the response on an ICMP error
*
* XXX theoretically ICMP_ECHOREP and the other reply's are
* ICMP query's as well, but adding them here seems strange XXX
*/
if ((icmp->icmp_type != ICMP_ECHO) &&
(icmp->icmp_type != ICMP_TSTAMP) &&
(icmp->icmp_type != ICMP_IREQ) &&
(icmp->icmp_type != ICMP_MASKREQ))
return NULL;
/*
* perform a lookup of the ICMP packet in the state table
*/
hv = (pr = oip->ip_p);
hv += (src.s_addr = oip->ip_src.s_addr);
hv += (dst.s_addr = oip->ip_dst.s_addr);
if (icmp->icmp_type == ICMP_ECHO) {
hv += icmp->icmp_id;
hv += icmp->icmp_seq;
}
hv %= fr_statesize;
oip->ip_len = ntohs(oip->ip_len);
fr_makefrip(oip->ip_hl << 2, oip, &ofin);
oip->ip_len = htons(oip->ip_len);
ofin.fin_ifp = fin->fin_ifp;
ofin.fin_out = !fin->fin_out;
ofin.fin_mp = NULL; /* if dereferenced, panic XXX */
READ_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_next)
if ((is->is_p == pr) &&
fr_matchsrcdst(is, src, dst, &ofin, NULL)) {
/*
* in the state table ICMP query's are stored
* with the type of the corresponding ICMP
* response. Correct here
*/
if (((is->is_type == ICMP_ECHOREPLY) &&
(icmp->icmp_id == is->is_icmp.ics_id) &&
(icmp->icmp_seq == is->is_icmp.ics_seq) &&
(icmp->icmp_type == ICMP_ECHO)) ||
(is->is_type - 1 == ic->icmp_type)) {
ips_stats.iss_hits++;
is->is_pkts++;
is->is_bytes += ip->ip_len;
fr = is->is_rule;
RWLOCK_EXIT(&ipf_state);
return fr;
}
}
RWLOCK_EXIT(&ipf_state);
return NULL;
};
if ((oip->ip_p != IPPROTO_TCP) && (oip->ip_p != IPPROTO_UDP))
return NULL;
tcp = (tcphdr_t *)((char *)oip + (oip->ip_hl << 2));
dport = tcp->th_dport;
sport = tcp->th_sport;
hv = (pr = oip->ip_p);
hv += (src.s_addr = oip->ip_src.s_addr);
hv += (dst.s_addr = oip->ip_dst.s_addr);
hv += dport;
hv += sport;
hv %= fr_statesize;
/*
* we make an fin entry to be able to feed it to
* matchsrcdst note that not all fields are encessary
* but this is the cleanest way. Note further we fill
* in fin_mp such that if someone uses it we'll get
* a kernel panic. fr_matchsrcdst does not use this.
*
* watch out here, as ip is in host order and oip in network
* order. Any change we make must be undone afterwards.
*/
savelen = oip->ip_len;
oip->ip_len = ip->ip_len - (ip->ip_hl << 2) - ICMPERR_ICMPHLEN;
fr_makefrip(oip->ip_hl << 2, oip, &ofin);
oip->ip_len = savelen;
ofin.fin_ifp = fin->fin_ifp;
ofin.fin_out = !fin->fin_out;
ofin.fin_mp = NULL; /* if dereferenced, panic XXX */
READ_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_next) {
/*
* Only allow this icmp though if the
* encapsulated packet was allowed through the
* other way around. Note that the minimal amount
* of info present does not allow for checking against
* tcp internals such as seq and ack numbers.
*/
if ((is->is_p == pr) &&
fr_matchsrcdst(is, src, dst, &ofin, tcp)) {
fr = is->is_rule;
ips_stats.iss_hits++;
/*
* we must swap src and dst here because the icmp
* comes the other way around
*/
is->is_pkts++;
is->is_bytes += ip->ip_len;
/*
* we deliberately do not touch the timeouts
* for the accompanying state table entry.
* It remains to be seen if that is correct. XXX
*/
RWLOCK_EXIT(&ipf_state);
return fr;
}
}
RWLOCK_EXIT(&ipf_state);
return NULL;
}
/*
* Check if a packet has a registered state.
*/
frentry_t *fr_checkstate(ip, fin)
ip_t *ip;
fr_info_t *fin;
{
register struct in_addr dst, src;
register ipstate_t *is, **isp;
register u_char pr;
u_int hv, hvm, hlen, tryagain, pass;
struct icmp *ic;
frentry_t *fr;
tcphdr_t *tcp;
if ((ip->ip_off & IP_OFFMASK) || (fin->fin_fi.fi_fl & FI_SHORT))
return NULL;
is = NULL;
hlen = fin->fin_hlen;
tcp = (tcphdr_t *)((char *)ip + hlen);
ic = (struct icmp *)tcp;
hv = (pr = ip->ip_p);
hv += (src.s_addr = ip->ip_src.s_addr);
hv += (dst.s_addr = ip->ip_dst.s_addr);
/*
* Search the hash table for matching packet header info.
*/
switch (ip->ip_p)
{
case IPPROTO_ICMP :
if ((ic->icmp_type == ICMP_ECHO) ||
(ic->icmp_type == ICMP_ECHOREPLY)) {
hv += ic->icmp_id;
hv += ic->icmp_seq;
}
hv %= fr_statesize;
READ_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_next)
if ((is->is_p == pr) &&
fr_matchsrcdst(is, src, dst, fin, NULL)) {
if ((is->is_type == ICMP_ECHOREPLY) &&
(ic->icmp_type == ICMP_ECHO) &&
(ic->icmp_id == is->is_icmp.ics_id) &&
(ic->icmp_seq == is->is_icmp.ics_seq))
;
else if (is->is_type != ic->icmp_type)
continue;
is->is_age = fr_icmptimeout;
break;
}
if (is != NULL)
break;
RWLOCK_EXIT(&ipf_state);
/*
* No matching icmp state entry. Perhaps this is a
* response to another state entry.
*/
fr = fr_checkicmpmatchingstate(ip, fin);
if (fr)
return fr;
break;
case IPPROTO_TCP :
{
register u_short dport = tcp->th_dport, sport = tcp->th_sport;
tryagain = 0;
retry_tcp:
hvm = hv % fr_statesize;
WRITE_ENTER(&ipf_state);
for (isp = &ips_table[hvm]; (is = *isp);
isp = &is->is_next)
if ((is->is_p == pr) &&
fr_matchsrcdst(is, src, dst, fin, tcp)) {
if (fr_tcpstate(is, fin, ip, tcp)) {
#ifndef _KERNEL
if (tcp->th_flags & TCP_CLOSE) {
*isp = is->is_next;
isp = &ips_table[hvm];
if (ips_table[hvm] == NULL)
ips_stats.iss_inuse--;
fr_delstate(is);
ips_num--;
}
#endif
break;
}
is = NULL;
break;
}
if (is != NULL)
break;
RWLOCK_EXIT(&ipf_state);
hv += dport;
hv += sport;
if (tryagain == 0) {
tryagain = 1;
goto retry_tcp;
}
break;
}
case IPPROTO_UDP :
{
register u_short dport = tcp->th_dport, sport = tcp->th_sport;
tryagain = 0;
retry_udp:
hvm = hv % fr_statesize;
/*
* Nothing else to match on but ports. and IP#'s
*/
READ_ENTER(&ipf_state);
for (is = ips_table[hvm]; is; is = is->is_next)
if ((is->is_p == pr) &&
fr_matchsrcdst(is, src, dst, fin, tcp)) {
is->is_age = fr_udptimeout;
break;
}
if (is != NULL)
break;
RWLOCK_EXIT(&ipf_state);
hv += dport;
hv += sport;
if (tryagain == 0) {
tryagain = 1;
goto retry_udp;
}
break;
}
default :
break;
}
if (is == NULL) {
ATOMIC_INC(ips_stats.iss_miss);
return NULL;
}
MUTEX_ENTER(&ipf_rw);
is->is_bytes += ip->ip_len;
ips_stats.iss_hits++;
is->is_pkts++;
MUTEX_EXIT(&ipf_rw);
fr = is->is_rule;
fin->fin_fr = fr;
pass = is->is_pass;
RWLOCK_EXIT(&ipf_state);
if (fin->fin_fi.fi_fl & FI_FRAG)
ipfr_newfrag(ip, fin, pass ^ FR_KEEPSTATE);
return fr;
}
static void fr_delstate(is)
ipstate_t *is;
{
frentry_t *fr;
fr = is->is_rule;
if (fr != NULL) {
ATOMIC_DEC(fr->fr_ref);
if (fr->fr_ref == 0)
KFREE(fr);
}
KFREE(is);
}
/*
* Free memory in use by all state info. kept.
*/
void fr_stateunload()
{
register int i;
register ipstate_t *is, **isp;
WRITE_ENTER(&ipf_state);
for (i = fr_statesize - 1; i >= 0; i--)
for (isp = &ips_table[i]; (is = *isp); ) {
*isp = is->is_next;
fr_delstate(is);
ips_num--;
}
ips_stats.iss_inuse = 0;
ips_num = 0;
RWLOCK_EXIT(&ipf_state);
KFREES(ips_table, fr_statesize * sizeof(ipstate_t *));
ips_table = NULL;
}
/*
* Slowly expire held state for thingslike UDP and ICMP. Timeouts are set
* in expectation of this being called twice per second.
*/
void fr_timeoutstate()
{
register int i;
register ipstate_t *is, **isp;
#if defined(_KERNEL) && !SOLARIS
int s;
#endif
SPL_NET(s);
WRITE_ENTER(&ipf_state);
for (i = fr_statesize - 1; i >= 0; i--)
for (isp = &ips_table[i]; (is = *isp); )
if (is->is_age && !--is->is_age) {
*isp = is->is_next;
if (is->is_p == IPPROTO_TCP)
ips_stats.iss_fin++;
else
ips_stats.iss_expire++;
if (ips_table[i] == NULL)
ips_stats.iss_inuse--;
#ifdef IPFILTER_LOG
ipstate_log(is, ISL_EXPIRE);
#endif
fr_delstate(is);
ips_num--;
} else
isp = &is->is_next;
if (fr_state_doflush) {
(void) fr_state_flush(1);
fr_state_doflush = 0;
}
RWLOCK_EXIT(&ipf_state);
SPL_X(s);
}
/*
* Original idea freom Pradeep Krishnan for use primarily with NAT code.
* (pkrishna@netcom.com)
*/
void fr_tcp_age(age, state, ip, fin, dir)
u_long *age;
u_char *state;
ip_t *ip;
fr_info_t *fin;
int dir;
{
tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
u_char flags = tcp->th_flags;
int dlen, ostate;
ostate = state[1 - dir];
dlen = ip->ip_len - fin->fin_hlen - (tcp->th_off << 2);
if (flags & TH_RST) {
if (!(tcp->th_flags & TH_PUSH) && !dlen) {
*age = fr_tcpclosed;
state[dir] = TCPS_CLOSED;
} else {
*age = fr_tcpclosewait;
state[dir] = TCPS_CLOSE_WAIT;
}
return;
}
*age = fr_tcptimeout; /* 1 min */
switch(state[dir])
{
case TCPS_CLOSED:
if ((flags & (TH_FIN|TH_SYN|TH_RST|TH_ACK)) == TH_ACK) {
state[dir] = TCPS_ESTABLISHED;
*age = fr_tcpidletimeout;
}
case TCPS_FIN_WAIT_2:
if ((flags & TH_OPENING) == TH_OPENING)
state[dir] = TCPS_SYN_RECEIVED;
else if (flags & TH_SYN)
state[dir] = TCPS_SYN_SENT;
break;
case TCPS_SYN_RECEIVED:
case TCPS_SYN_SENT:
if ((flags & (TH_FIN|TH_ACK)) == TH_ACK) {
state[dir] = TCPS_ESTABLISHED;
*age = fr_tcpidletimeout;
} else if ((flags & (TH_FIN|TH_ACK)) == (TH_FIN|TH_ACK)) {
state[dir] = TCPS_CLOSE_WAIT;
if (!(flags & TH_PUSH) && !dlen &&
ostate > TCPS_ESTABLISHED)
*age = fr_tcplastack;
else
*age = fr_tcpclosewait;
}
break;
case TCPS_ESTABLISHED:
if (flags & TH_FIN) {
state[dir] = TCPS_CLOSE_WAIT;
if (!(flags & TH_PUSH) && !dlen &&
ostate > TCPS_ESTABLISHED)
*age = fr_tcplastack;
else
*age = fr_tcpclosewait;
} else {
if (ostate < TCPS_CLOSE_WAIT)
*age = fr_tcpidletimeout;
}
break;
case TCPS_CLOSE_WAIT:
if ((flags & TH_FIN) && !(flags & TH_PUSH) && !dlen &&
ostate > TCPS_ESTABLISHED) {
*age = fr_tcplastack;
state[dir] = TCPS_LAST_ACK;
} else
*age = fr_tcpclosewait;
break;
case TCPS_LAST_ACK:
if (flags & TH_ACK) {
state[dir] = TCPS_FIN_WAIT_2;
if (!(flags & TH_PUSH) && !dlen &&
ostate > TCPS_ESTABLISHED)
*age = fr_tcplastack;
else {
*age = fr_tcpclosewait;
state[dir] = TCPS_CLOSE_WAIT;
}
}
break;
}
}
#ifdef IPFILTER_LOG
void ipstate_log(is, type)
struct ipstate *is;
u_int type;
{
struct ipslog ipsl;
void *items[1];
size_t sizes[1];
int types[1];
ipsl.isl_type = type;
ipsl.isl_pkts = is->is_pkts;
ipsl.isl_bytes = is->is_bytes;
ipsl.isl_src = is->is_src;
ipsl.isl_dst = is->is_dst;
ipsl.isl_p = is->is_p;
ipsl.isl_flags = is->is_flags;
if (ipsl.isl_p == IPPROTO_TCP || ipsl.isl_p == IPPROTO_UDP) {
ipsl.isl_sport = is->is_sport;
ipsl.isl_dport = is->is_dport;
if (ipsl.isl_p == IPPROTO_TCP) {
ipsl.isl_state[0] = is->is_state[0];
ipsl.isl_state[1] = is->is_state[1];
}
} else if (ipsl.isl_p == IPPROTO_ICMP)
ipsl.isl_itype = is->is_icmp.ics_type;
else {
ipsl.isl_ps.isl_filler[0] = 0;
ipsl.isl_ps.isl_filler[1] = 0;
}
items[0] = &ipsl;
sizes[0] = sizeof(ipsl);
types[0] = 0;
(void) ipllog(IPL_LOGSTATE, NULL, items, sizes, types, 1);
}
#endif
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