FreeBSD-5.3/sys/contrib/ipfilter/netinet/ip_state.c
/*
* Copyright (C) 1995-2002 by Darren Reed.
*
* See the IPFILTER.LICENCE file for details on licencing.
*/
#if defined(__sgi) && (IRIX > 602)
# include <sys/ptimers.h>
#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(__FreeBSD_version) && \
(__FreeBSD_version >= 400000) && !defined(KLD_MODULE)
#include "opt_inet6.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) || defined(_KERNEL)) && (__FreeBSD_version >= 220000)
# 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>
#ifndef linux
# include <sys/protosw.h>
#endif
#include <sys/socket.h>
#if (defined(_KERNEL) || 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_state.h"
#ifdef USE_INET6
#include <netinet/icmp6.h>
#endif
#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
#if !defined(lint)
static const char sccsid[] = "@(#)ip_state.c 1.8 6/5/96 (C) 1993-2000 Darren Reed";
/* static const char rcsid[] = "@(#)$Id: ip_state.c,v 2.30.2.38 2001/07/23 13:49:46 darrenr Exp $"; */
static const char rcsid[] = "@(#)$FreeBSD: src/sys/contrib/ipfilter/netinet/ip_state.c,v 1.33 2004/06/21 22:46:36 darrenr Exp $";
#endif
#ifndef MIN
# define MIN(a,b) (((a)<(b))?(a):(b))
#endif
#define TCP_CLOSE (TH_FIN|TH_RST)
static ipstate_t **ips_table = NULL;
static int ips_num = 0;
static int ips_wild = 0;
static ips_stat_t ips_stats;
#if (SOLARIS || defined(__sgi)) && defined(_KERNEL)
extern KRWLOCK_T ipf_state, ipf_mutex;
extern kmutex_t ipf_rw;
#endif
#ifdef USE_INET6
static frentry_t *fr_checkicmp6matchingstate __P((ip6_t *, fr_info_t *));
#endif
static int fr_matchsrcdst __P((ipstate_t *, union i6addr, union i6addr,
fr_info_t *, tcphdr_t *));
static frentry_t *fr_checkicmpmatchingstate __P((ip_t *, fr_info_t *));
static int fr_matchicmpqueryreply __P((int, ipstate_t *, icmphdr_t *, int));
static int fr_state_flush __P((int, int));
static ips_stat_t *fr_statetstats __P((void));
static void fr_delstate __P((ipstate_t *));
static int fr_state_remove __P((caddr_t));
static void fr_ipsmove __P((ipstate_t **, ipstate_t *, u_int));
static int fr_tcpoptions __P((tcphdr_t *));
int fr_stputent __P((caddr_t));
int fr_stgetent __P((caddr_t));
void fr_stinsert __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 = 120,
fr_tcphalfclosed = 2 * 2 * 3600, /* 2 hours */
fr_udptimeout = 240,
fr_udpacktimeout = 24,
fr_icmptimeout = 120,
fr_icmpacktimeout = 12;
int fr_statemax = IPSTATE_MAX,
fr_statesize = IPSTATE_SIZE;
int fr_state_doflush = 0,
fr_state_lock = 0;
ipstate_t *ips_list = NULL;
static int icmpreplytype4[ICMP_MAXTYPE + 1];
#ifdef USE_INET6
static int icmpreplytype6[ICMP6_MAXTYPE + 1];
#endif
int fr_stateinit()
{
int i;
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;
/* fill icmp reply type table */
for (i = 0; i <= ICMP_MAXTYPE; i++)
icmpreplytype4[i] = -1;
icmpreplytype4[ICMP_ECHO] = ICMP_ECHOREPLY;
icmpreplytype4[ICMP_TSTAMP] = ICMP_TSTAMPREPLY;
icmpreplytype4[ICMP_IREQ] = ICMP_IREQREPLY;
icmpreplytype4[ICMP_MASKREQ] = ICMP_MASKREPLY;
#ifdef USE_INET6
/* fill icmp reply type table */
for (i = 0; i <= ICMP6_MAXTYPE; i++)
icmpreplytype6[i] = -1;
icmpreplytype6[ICMP6_ECHO_REQUEST] = ICMP6_ECHO_REPLY;
icmpreplytype6[ICMP6_MEMBERSHIP_QUERY] = ICMP6_MEMBERSHIP_REPORT;
icmpreplytype6[ICMP6_NI_QUERY] = ICMP6_NI_REPLY;
icmpreplytype6[ND_ROUTER_SOLICIT] = ND_ROUTER_ADVERT;
icmpreplytype6[ND_NEIGHBOR_SOLICIT] = ND_NEIGHBOR_ADVERT;
#endif
return 0;
}
static ips_stat_t *fr_statetstats()
{
ips_stats.iss_active = ips_num;
ips_stats.iss_table = ips_table;
ips_stats.iss_list = ips_list;
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.
* which == 2 : flush TCP connections which have been idle for a long time,
* starting at > 4 days idle and working back in successive half-
* days to at most 12 hours old.
*/
static int fr_state_flush(which, proto)
int which, proto;
{
ipstate_t *is, **isp;
#if defined(_KERNEL) && !SOLARIS
int s;
#endif
int delete, removed = 0, try;
SPL_NET(s);
for (isp = &ips_list; (is = *isp); ) {
delete = 0;
if ((proto != 0) && (is->is_v != proto))
continue;
switch (which)
{
case 0 :
delete = 1;
break;
case 1 :
case 2 :
if (is->is_p != IPPROTO_TCP)
break;
if ((is->is_state[0] != TCPS_ESTABLISHED) ||
(is->is_state[1] != TCPS_ESTABLISHED))
delete = 1;
break;
}
if (delete) {
if (is->is_p == IPPROTO_TCP)
ips_stats.iss_fin++;
else
ips_stats.iss_expire++;
#ifdef IPFILTER_LOG
ipstate_log(is, ISL_FLUSH);
#endif
fr_delstate(is);
removed++;
} else
isp = &is->is_next;
}
/*
* Asked to remove inactive entries, try again if first attempt
* failed. In this case, 86400 is half a day because the counter is
* activated every half second.
*/
if ((which == 2) && (removed == 0)) {
try = 86400; /* half a day */
for (; (try < FIVE_DAYS) && (removed == 0); try += 86400) {
for (isp = &ips_list; (is = *isp); ) {
delete = 0;
if ((is->is_p == IPPROTO_TCP) &&
((is->is_state[0] == TCPS_ESTABLISHED) ||
(is->is_state[1] == TCPS_ESTABLISHED)) &&
(is->is_age < try)) {
ips_stats.iss_fin++;
delete = 1;
} else if ((is->is_p != IPPROTO_TCP) &&
(is->is_pkts > 1)) {
ips_stats.iss_expire++;
delete = 1;
}
if (delete) {
#ifdef IPFILTER_LOG
ipstate_log(is, ISL_FLUSH);
#endif
fr_delstate(is);
removed++;
} else
isp = &is->is_next;
}
}
}
SPL_X(s);
return removed;
}
static int fr_state_remove(data)
caddr_t data;
{
ipstate_t *sp, st;
int error;
sp = &st;
error = IRCOPYPTR(data, (caddr_t)&st, sizeof(st));
if (error)
return EFAULT;
WRITE_ENTER(&ipf_state);
for (sp = ips_list; sp; sp = sp->is_next)
if ((sp->is_p == st.is_p) && (sp->is_v == st.is_v) &&
!bcmp((char *)&sp->is_src, (char *)&st.is_src,
sizeof(st.is_src)) &&
!bcmp((char *)&sp->is_dst, (char *)&st.is_dst,
sizeof(st.is_dst)) &&
!bcmp((char *)&sp->is_ps, (char *)&st.is_ps,
sizeof(st.is_ps))) {
#ifdef IPFILTER_LOG
ipstate_log(sp, ISL_REMOVE);
#endif
fr_delstate(sp);
RWLOCK_EXIT(&ipf_state);
return 0;
}
RWLOCK_EXIT(&ipf_state);
return ESRCH;
}
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 SIOCDELST :
error = fr_state_remove(data);
break;
case SIOCIPFFL :
error = IRCOPY(data, (caddr_t)&arg, sizeof(arg));
if (error)
break;
if (arg == 0 || arg == 1) {
WRITE_ENTER(&ipf_state);
ret = fr_state_flush(arg, 4);
RWLOCK_EXIT(&ipf_state);
error = IWCOPY((caddr_t)&ret, data, sizeof(ret));
} else
error = EINVAL;
break;
#ifdef USE_INET6
case SIOCIPFL6 :
error = IRCOPY(data, (caddr_t)&arg, sizeof(arg));
if (error)
break;
if (arg == 0 || arg == 1) {
WRITE_ENTER(&ipf_state);
ret = fr_state_flush(arg, 6);
RWLOCK_EXIT(&ipf_state);
error = IWCOPY((caddr_t)&ret, data, sizeof(ret));
} else
error = EINVAL;
break;
#endif
#ifdef IPFILTER_LOG
case SIOCIPFFB :
if (!(mode & FWRITE))
error = EPERM;
else {
int tmp;
tmp = ipflog_clear(IPL_LOGSTATE);
IWCOPY((char *)&tmp, data, sizeof(tmp));
}
break;
#endif
case SIOCGETFS :
error = IWCOPYPTR((caddr_t)fr_statetstats(), data,
sizeof(ips_stat_t));
break;
case FIONREAD :
#ifdef IPFILTER_LOG
arg = (int)iplused[IPL_LOGSTATE];
error = IWCOPY((caddr_t)&arg, (caddr_t)data, sizeof(arg));
#endif
break;
case SIOCSTLCK :
error = fr_lock(data, &fr_state_lock);
break;
case SIOCSTPUT :
if (!fr_state_lock) {
error = EACCES;
break;
}
error = fr_stputent(data);
break;
case SIOCSTGET :
if (!fr_state_lock) {
error = EACCES;
break;
}
error = fr_stgetent(data);
break;
default :
error = EINVAL;
break;
}
return error;
}
/*
* Copy out state information from the kernel to a user space process.
*/
int fr_stgetent(data)
caddr_t data;
{
register ipstate_t *is, *isn;
ipstate_save_t ips;
int error;
error = IRCOPYPTR(data, (caddr_t)&ips, sizeof(ips));
if (error)
return error;
isn = ips.ips_next;
if (!isn) {
isn = ips_list;
if (isn == NULL) {
if (ips.ips_next == NULL)
return ENOENT;
return 0;
}
} else {
/*
* Make sure the pointer we're copying from exists in the
* current list of entries. Security precaution to prevent
* copying of random kernel data.
*/
for (is = ips_list; is; is = is->is_next)
if (is == isn)
break;
if (!is)
return ESRCH;
}
ips.ips_next = isn->is_next;
bcopy((char *)isn, (char *)&ips.ips_is, sizeof(ips.ips_is));
if (isn->is_rule)
bcopy((char *)isn->is_rule, (char *)&ips.ips_fr,
sizeof(ips.ips_fr));
error = IWCOPYPTR((caddr_t)&ips, data, sizeof(ips));
if (error)
error = EFAULT;
return error;
}
int fr_stputent(data)
caddr_t data;
{
register ipstate_t *is, *isn;
ipstate_save_t ips;
int error, out, i;
frentry_t *fr;
char *name;
error = IRCOPYPTR(data, (caddr_t)&ips, sizeof(ips));
if (error)
return error;
KMALLOC(isn, ipstate_t *);
if (isn == NULL)
return ENOMEM;
bcopy((char *)&ips.ips_is, (char *)isn, sizeof(*isn));
fr = isn->is_rule;
if (fr != NULL) {
if (isn->is_flags & FI_NEWFR) {
KMALLOC(fr, frentry_t *);
if (fr == NULL) {
KFREE(isn);
return ENOMEM;
}
bcopy((char *)&ips.ips_fr, (char *)fr, sizeof(*fr));
out = fr->fr_flags & FR_OUTQUE ? 1 : 0;
isn->is_rule = fr;
ips.ips_is.is_rule = fr;
/*
* Look up all the interface names in the rule.
*/
for (i = 0; i < 4; i++) {
name = fr->fr_ifnames[i];
if ((name[1] == '\0') &&
((name[0] == '-') || (name[0] == '*'))) {
fr->fr_ifas[i] = NULL;
} else if (*name != '\0') {
fr->fr_ifas[i] = GETUNIT(name,
fr->fr_v);
if (fr->fr_ifas[i] == NULL)
fr->fr_ifas[i] = (void *)-1;
else {
strncpy(isn->is_ifname[i],
IFNAME(fr->fr_ifas[i]),
IFNAMSIZ);
}
}
isn->is_ifp[out] = fr->fr_ifas[i];
}
/*
* send a copy back to userland of what we ended up
* to allow for verification.
*/
error = IWCOPYPTR((caddr_t)&ips, data, sizeof(ips));
if (error) {
KFREE(isn);
KFREE(fr);
return EFAULT;
}
} else {
for (is = ips_list; is; is = is->is_next)
if (is->is_rule == fr)
break;
if (!is) {
KFREE(isn);
return ESRCH;
}
}
}
fr_stinsert(isn);
return 0;
}
/*
* Insert a state table entry manually.
*/
void fr_stinsert(is)
register ipstate_t *is;
{
register u_int hv = is->is_hv;
char *name;
int i;
MUTEX_INIT(&is->is_lock, "ipf state entry", NULL);
/*
* Look up all the interface names in the state entry.
*/
for (i = 0; i < 4; i++) {
name = is->is_ifname[i];
if ((name[1] == '\0') &&
((name[0] == '-') || (name[0] == '*'))) {
is->is_ifp[0] = NULL;
} else if (*name != '\0') {
is->is_ifp[i] = GETUNIT(name, is->is_v);
if (is->is_ifp[i] == NULL)
is->is_ifp[i] = (void *)-1;
}
}
/*
* add into list table.
*/
if (ips_list)
ips_list->is_pnext = &is->is_next;
is->is_pnext = &ips_list;
is->is_next = ips_list;
ips_list = is;
if (ips_table[hv])
ips_table[hv]->is_phnext = &is->is_hnext;
else
ips_stats.iss_inuse++;
is->is_phnext = ips_table + hv;
is->is_hnext = ips_table[hv];
ips_table[hv] = is;
ips_num++;
}
/*
* Create a new ipstate structure and hang it off the hash table.
*/
ipstate_t *fr_addstate(ip, fin, stsave, flags)
ip_t *ip;
fr_info_t *fin;
ipstate_t **stsave;
u_int flags;
{
register tcphdr_t *tcp = NULL;
register ipstate_t *is;
register u_int hv;
struct icmp *ic;
ipstate_t ips;
int out, ws;
u_int pass;
void *ifp;
if (fr_state_lock || (fin->fin_off != 0) || (fin->fin_fl & FI_SHORT) ||
(fin->fin_misc & FM_BADSTATE))
return NULL;
if (ips_num == fr_statemax) {
ips_stats.iss_max++;
fr_state_doflush = 1;
return NULL;
}
out = fin->fin_out;
is = &ips;
bzero((char *)is, sizeof(*is));
ips.is_age = 1;
/*
* Copy and calculate...
*/
hv = (is->is_p = fin->fin_fi.fi_p);
is->is_src = fin->fin_fi.fi_src;
hv += is->is_saddr;
is->is_dst = fin->fin_fi.fi_dst;
hv += is->is_daddr;
#ifdef USE_INET6
if (fin->fin_v == 6) {
if ((is->is_p == IPPROTO_ICMPV6) &&
IN6_IS_ADDR_MULTICAST(&is->is_dst.in6)) {
/*
* So you can do keep state with neighbour discovery.
*/
flags |= FI_W_DADDR;
hv -= is->is_daddr;
} else {
hv += is->is_dst.i6[1];
hv += is->is_dst.i6[2];
hv += is->is_dst.i6[3];
}
hv += is->is_src.i6[1];
hv += is->is_src.i6[2];
hv += is->is_src.i6[3];
}
#endif
switch (is->is_p)
{
int off;
#ifdef USE_INET6
case IPPROTO_ICMPV6 :
ic = (struct icmp *)fin->fin_dp;
if ((ic->icmp_type & ICMP6_INFOMSG_MASK) == 0)
return NULL;
switch (ic->icmp_type)
{
case ICMP6_ECHO_REQUEST :
is->is_icmp.ics_type = ic->icmp_type;
hv += (is->is_icmp.ics_id = ic->icmp_id);
hv += (is->is_icmp.ics_seq = ic->icmp_seq);
break;
case ICMP6_MEMBERSHIP_QUERY :
case ND_ROUTER_SOLICIT :
case ND_NEIGHBOR_SOLICIT :
case ICMP6_NI_QUERY :
is->is_icmp.ics_type = ic->icmp_type;
break;
default :
return NULL;
}
ATOMIC_INCL(ips_stats.iss_icmp);
is->is_age = fr_icmptimeout;
break;
#endif
case IPPROTO_ICMP :
ic = (struct icmp *)fin->fin_dp;
switch (ic->icmp_type)
{
case ICMP_ECHO :
case ICMP_TSTAMP :
case ICMP_IREQ :
case ICMP_MASKREQ :
is->is_icmp.ics_type = ic->icmp_type;
hv += (is->is_icmp.ics_id = ic->icmp_id);
hv += (is->is_icmp.ics_seq = ic->icmp_seq);
break;
default :
return NULL;
}
ATOMIC_INCL(ips_stats.iss_icmp);
is->is_age = fr_icmptimeout;
break;
case IPPROTO_TCP :
tcp = (tcphdr_t *)fin->fin_dp;
if (tcp->th_flags & TH_RST)
return NULL;
/*
* The endian of the ports doesn't matter, but the ack and
* sequence numbers do as we do mathematics on them later.
*/
is->is_sport = htons(fin->fin_data[0]);
is->is_dport = htons(fin->fin_data[1]);
if ((flags & (FI_W_DPORT|FI_W_SPORT)) == 0) {
hv += is->is_sport;
hv += is->is_dport;
}
if ((flags & FI_IGNOREPKT) == 0) {
is->is_send = ntohl(tcp->th_seq) + fin->fin_dlen -
(off = (tcp->th_off << 2)) +
((tcp->th_flags & TH_SYN) ? 1 : 0) +
((tcp->th_flags & TH_FIN) ? 1 : 0);
is->is_maxsend = is->is_send;
if ((tcp->th_flags & TH_SYN) &&
((tcp->th_off << 2) >= (sizeof(*tcp) + 4))) {
ws = fr_tcpoptions(tcp);
if (ws >= 0)
is->is_swscale = ws;
}
}
is->is_maxdwin = 1;
is->is_maxswin = ntohs(tcp->th_win);
if (is->is_maxswin == 0)
is->is_maxswin = 1;
if ((tcp->th_flags & TH_OPENING) == TH_SYN)
is->is_fsm = 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.
*/
ATOMIC_INCL(ips_stats.iss_tcp);
break;
case IPPROTO_UDP :
tcp = (tcphdr_t *)fin->fin_dp;
is->is_sport = htons(fin->fin_data[0]);
is->is_dport = htons(fin->fin_data[1]);
if ((flags & (FI_W_DPORT|FI_W_SPORT)) == 0) {
hv += is->is_sport;
hv += is->is_dport;
}
ATOMIC_INCL(ips_stats.iss_udp);
is->is_age = fr_udptimeout;
break;
default :
is->is_age = fr_udptimeout;
break;
}
KMALLOC(is, ipstate_t *);
if (is == NULL) {
ATOMIC_INCL(ips_stats.iss_nomem);
return NULL;
}
bcopy((char *)&ips, (char *)is, sizeof(*is));
hv %= fr_statesize;
is->is_hv = hv;
is->is_rule = fin->fin_fr;
if (is->is_rule != NULL) {
is->is_group = is->is_rule->fr_group;
ATOMIC_INC32(is->is_rule->fr_ref);
pass = is->is_rule->fr_flags;
is->is_frage[0] = is->is_rule->fr_age[0];
is->is_frage[1] = is->is_rule->fr_age[1];
if (is->is_frage[0] != 0)
is->is_age = is->is_frage[0];
is->is_ifp[(out << 1) + 1] = is->is_rule->fr_ifas[1];
is->is_ifp[(1 - out) << 1] = is->is_rule->fr_ifas[2];
is->is_ifp[((1 - out) << 1) + 1] = is->is_rule->fr_ifas[3];
if (((ifp = is->is_rule->fr_ifas[1]) != NULL) &&
(ifp != (void *)-1))
strncpy(is->is_ifname[(out << 1) + 1],
IFNAME(ifp), IFNAMSIZ);
if (((ifp = is->is_rule->fr_ifas[2]) != NULL) &&
(ifp != (void *)-1))
strncpy(is->is_ifname[(1 - out) << 1],
IFNAME(ifp), IFNAMSIZ);
if (((ifp = is->is_rule->fr_ifas[3]) != NULL) &&
(ifp != (void *)-1))
strncpy(is->is_ifname[((1 - out) << 1) + 1],
IFNAME(ifp), IFNAMSIZ);
} else
pass = fr_flags;
is->is_ifp[out << 1] = fin->fin_ifp;
strncpy(is->is_ifname[out << 1], IFNAME(fin->fin_ifp), IFNAMSIZ);
WRITE_ENTER(&ipf_state);
is->is_pass = pass;
if ((flags & FI_IGNOREPKT) == 0) {
is->is_pkts = 1;
is->is_bytes = fin->fin_dlen + fin->fin_hlen;
}
/*
* 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_v = fin->fin_v;
is->is_rulen = fin->fin_rule;
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_fl & FI_CMP;
is->is_flags |= FI_CMP << 4;
is->is_flags |= flags & (FI_WILDP|FI_WILDA);
if (flags & (FI_WILDP|FI_WILDA))
ips_wild++;
if (pass & FR_LOGFIRST)
is->is_pass &= ~(FR_LOGFIRST|FR_LOG);
fr_stinsert(is);
is->is_me = stsave;
if (is->is_p == IPPROTO_TCP) {
fr_tcp_age(&is->is_age, is->is_state, fin,
0, is->is_fsm); /* 0 = packet from the source */
}
#ifdef IPFILTER_LOG
ipstate_log(is, ISL_NEW);
#endif
RWLOCK_EXIT(&ipf_state);
fin->fin_rev = IP6NEQ(is->is_dst, fin->fin_fi.fi_dst);
if ((fin->fin_fl & FI_FRAG) && (pass & FR_KEEPFRAG))
ipfr_newfrag(ip, fin);
return is;
}
static int fr_tcpoptions(tcp)
tcphdr_t *tcp;
{
u_char *opt, *last;
int wscale;
opt = (u_char *) (tcp + 1);
last = ((u_char *)tcp) + (tcp->th_off << 2);
/* If we don't find wscale here, we need to clear it */
wscale = -2;
/* Termination condition picked such that opt[0 .. 2] exist */
while ((opt < last - 2) && (*opt != TCPOPT_EOL)) {
switch (*opt) {
case TCPOPT_NOP:
opt++;
continue;
case TCPOPT_WSCALE:
/* Proper length ? */
if (opt[1] == 3) {
if (opt[2] > 14)
wscale = 14;
else
wscale = opt[2];
}
break;
default:
/* Unknown options must be two bytes+ */
if (opt[1] < 2)
break;
opt += opt[1];
continue;
}
break;
}
return wscale;
}
/*
* 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_32_t win, maxwin;
int ret = 0, off;
int source;
int wscale;
/*
* Find difference between last checked packet and this packet.
*/
source = IP6EQ(fin->fin_fi.fi_src, is->is_src);
if (source && (ntohs(is->is_sport) != fin->fin_data[0]))
source = 0;
fdata = &is->is_tcp.ts_data[!source];
tdata = &is->is_tcp.ts_data[source];
off = tcp->th_off << 2;
seq = ntohl(tcp->th_seq);
ack = ntohl(tcp->th_ack);
win = ntohs(tcp->th_win);
end = seq + fin->fin_dlen - off +
((tcp->th_flags & TH_SYN) ? 1 : 0) +
((tcp->th_flags & TH_FIN) ? 1 : 0);
if ((tcp->th_flags & TH_SYN) && (off >= sizeof(*tcp) + 4))
wscale = fr_tcpoptions(tcp);
else
wscale = -1;
MUTEX_ENTER(&is->is_lock);
if (wscale >= 0)
fdata->td_wscale = wscale;
else if (wscale == -2)
fdata->td_wscale = tdata->td_wscale = 0;
if (!(tcp->th_flags & TH_SYN))
win <<= fdata->td_wscale;
if ((fdata->td_end == 0) &&
(!is->is_fsm || ((tcp->th_flags & TH_OPENING) == TH_OPENING))) {
/*
* Must be a (outgoing) SYN-ACK in reply to a SYN.
*/
fdata->td_end = end;
fdata->td_maxwin = 1;
fdata->td_maxend = end + win;
if (win == 0)
fdata->td_maxend++;
}
if (!(tcp->th_flags & TH_ACK)) { /* Pretend an ack was sent */
ack = tdata->td_end;
} 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, fdata->td_end - maxwin)) &&
/* XXX what about big packets */
#define MAXACKWINDOW 66000
(-ackskew <= (MAXACKWINDOW << tdata->td_wscale)) &&
( ackskew <= (MAXACKWINDOW << tdata->td_wscale))) {
/* if ackskew < 0 then this should be due to fragmented
* 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 parameters 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.
*/
/*
* Nearing end of connection, start timeout.
*/
/* source ? 0 : 1 -> !source */
if (fr_tcp_age(&is->is_age, is->is_state, fin, !source,
(int)is->is_fsm) == 0) {
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_INCL(ips_stats.iss_hits);
ret = 1;
}
}
MUTEX_EXIT(&is->is_lock);
if ((ret == 0) && ((tcp->th_flags & TH_OPENING) != TH_SYN))
fin->fin_misc |= FM_BADSTATE;
return ret;
}
/*
* Match a state table entry against an IP packet.
*/
static int fr_matchsrcdst(is, src, dst, fin, tcp)
ipstate_t *is;
union i6addr src, dst;
fr_info_t *fin;
tcphdr_t *tcp;
{
int ret = 0, rev, out, flags, idx;
u_short sp, dp;
void *ifp;
rev = IP6NEQ(is->is_dst, dst);
ifp = fin->fin_ifp;
out = fin->fin_out;
flags = is->is_flags & (FI_WILDA|FI_WILDP);
sp = 0;
dp = 0;
if (tcp != NULL) {
flags = is->is_flags;
sp = tcp->th_sport;
dp = tcp->th_dport;
if (!rev) {
if (!(flags & FI_W_SPORT) && (sp != is->is_sport))
rev = 1;
else if (!(flags & FI_W_DPORT) && (dp != is->is_dport))
rev = 1;
}
}
idx = (out << 1) + rev;
if ((is->is_ifp[idx] == NULL &&
(*is->is_ifname[idx] == '\0' || *is->is_ifname[idx] == '*')) ||
is->is_ifp[idx] == ifp)
ret = 1;
if (ret == 0)
return 0;
ret = 0;
if (rev == 0) {
if ((IP6EQ(is->is_dst, dst) || (flags & FI_W_DADDR)) &&
(IP6EQ(is->is_src, src) || (flags & FI_W_SADDR)) &&
(!tcp || ((sp == is->is_sport || flags & FI_W_SPORT) &&
(dp == is->is_dport || flags & FI_W_DPORT)))) {
ret = 1;
}
} else {
if ((IP6EQ(is->is_dst, src) || (flags & FI_W_DADDR)) &&
(IP6EQ(is->is_src, dst) || (flags & FI_W_SADDR)) &&
(!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_fl & (flags >> 4)) != (flags & FI_CMP)) ||
(fin->fin_fi.fi_optmsk != is->is_opt) ||
(fin->fin_fi.fi_secmsk != is->is_sec) ||
(fin->fin_fi.fi_auth != is->is_auth))
return 0;
flags = is->is_flags & (FI_WILDA|FI_WILDP);
if ((flags & (FI_W_SADDR|FI_W_DADDR))) {
if ((flags & FI_W_SADDR) != 0) {
if (rev == 0) {
is->is_src = fin->fin_fi.fi_src;
} else {
is->is_src = fin->fin_fi.fi_dst;
}
} else if ((flags & FI_W_DADDR) != 0) {
if (rev == 0) {
is->is_dst = fin->fin_fi.fi_dst;
} else {
is->is_dst = fin->fin_fi.fi_src;
}
}
is->is_flags &= ~(FI_W_SADDR|FI_W_DADDR);
if ((is->is_flags & (FI_WILDA|FI_WILDP)) == 0)
ips_wild--;
}
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);
ips_wild--;
}
ret = -1;
if (is->is_ifp[idx] == NULL &&
(*is->is_ifname[idx] == '\0' || *is->is_ifname[idx] == '*'))
ret = idx;
if (ret >= 0) {
is->is_ifp[ret] = ifp;
strncpy(is->is_ifname[ret], IFNAME(ifp),
sizeof(is->is_ifname[ret]));
}
fin->fin_rev = rev;
return 1;
}
static int fr_matchicmpqueryreply(v, is, icmp, rev)
int v;
ipstate_t *is;
icmphdr_t *icmp;
int rev;
{
if (v == 4) {
/*
* If we matched its type on the way in, then when going out
* it will still be the same type.
*/
if ((!rev && (icmp->icmp_type == is->is_type)) ||
(rev && (icmpreplytype4[is->is_type] == icmp->icmp_type))) {
if (icmp->icmp_type != ICMP_ECHOREPLY)
return 1;
if ((icmp->icmp_id == is->is_icmp.ics_id) &&
(icmp->icmp_seq == is->is_icmp.ics_seq))
return 1;
}
}
#ifdef USE_INET6
else if (is->is_v == 6) {
if ((!rev && (icmp->icmp_type == is->is_type)) ||
(rev && (icmpreplytype6[is->is_type] == icmp->icmp_type))) {
if (icmp->icmp_type != ICMP6_ECHO_REPLY)
return 1;
if ((icmp->icmp_id == is->is_icmp.ics_id) &&
(icmp->icmp_seq == is->is_icmp.ics_seq))
return 1;
}
}
#endif
return 0;
}
static frentry_t *fr_checkicmpmatchingstate(ip, fin)
ip_t *ip;
fr_info_t *fin;
{
register ipstate_t *is, **isp;
register u_short sport, dport;
register u_char pr;
u_short savelen, ohlen;
union i6addr dst, src;
struct icmp *ic;
icmphdr_t *icmp;
fr_info_t ofin;
int type, len;
tcphdr_t *tcp;
frentry_t *fr;
ip_t *oip;
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_v != 4) || (ip->ip_hl != 5)) ||
(fin->fin_plen < ICMPERR_MINPKTLEN))
return NULL;
ic = (struct icmp *)fin->fin_dp;
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 *)ic + ICMPERR_ICMPHLEN);
ohlen = oip->ip_hl << 2;
/*
* Check if the at least the old IP header (with options) and
* 8 bytes of payload is present.
*/
if (fin->fin_plen < ICMPERR_MAXPKTLEN + ohlen - sizeof(*oip))
return NULL;
/*
* Sanity checks.
*/
len = fin->fin_dlen - ICMPERR_ICMPHLEN;
if ((len <= 0) || (ohlen > len))
return NULL;
/*
* Is the buffer big enough for all of it ? It's the size of the IP
* header claimed in the encapsulated part which is of concern. It
* may be too big to be in this buffer but not so big that it's
* outside the ICMP packet, leading to TCP deref's causing problems.
* This is possible because we don't know how big oip_hl is when we
* do the pullup early in fr_check() and thus can't guarantee it is
* all here now.
*/
#ifdef _KERNEL
{
mb_t *m;
# if SOLARIS
m = fin->fin_qfm;
if ((char *)oip + len > (char *)m->b_wptr)
return NULL;
# else
m = *(mb_t **)fin->fin_mp;
if ((char *)oip + len > (char *)ip + m->m_len)
return NULL;
# endif
}
#endif
/*
* in the IPv4 case we must zero the i6addr union otherwise
* the IP6EQ and IP6NEQ macros produce the wrong results because
* of the 'junk' in the unused part of the union
*/
bzero((char *)&src, sizeof(src));
bzero((char *)&dst, sizeof(dst));
bzero((char *)&ofin, sizeof(ofin));
/*
* 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 that we
* fill in fin_mp such that if someone uses it we'll get
* a kernel panic. fr_matchsrcdst does not use this.
*/
ofin.fin_ifp = fin->fin_ifp;
ofin.fin_out = !fin->fin_out;
ofin.fin_mp = NULL;
ofin.fin_v = 4;
/*
* watch out here, as ip is in host order and oip in network
* order. Any change we make must be undone afterwards, like
* oip->ip_off - it is still in network byte order so fix it.
*/
savelen = oip->ip_len;
oip->ip_len = len;
oip->ip_off = ntohs(oip->ip_off);
(void) fr_makefrip(ohlen, oip, &ofin);
/*
* Reset the short flag here because in fr_matchsrcdst() the flags
* for the current packet (fin_fl) are compared against * those for
* the existing session.
*/
ofin.fin_fl &= ~FI_SHORT;
/*
* Put old values of ip_len and ip_off back as we don't know
* if we have to forward the packet (or process it again.
*/
oip->ip_len = savelen;
oip->ip_off = htons(oip->ip_off);
#if SOLARIS
ofin.fin_qfm = NULL;
#endif
fr = NULL;
switch (oip->ip_p)
{
case IPPROTO_ICMP :
icmp = (icmphdr_t *)((char *)oip + ohlen);
/*
* an 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);
src.in4 = oip->ip_src;
hv += src.in4.s_addr;
dst.in4 = oip->ip_dst;
hv += dst.in4.s_addr;
hv += icmp->icmp_id;
hv += icmp->icmp_seq;
hv %= fr_statesize;
READ_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_hnext)
if ((is->is_p == pr) && (is->is_v == 4) &&
(is->is_icmppkts < is->is_pkts) &&
fr_matchsrcdst(is, src, dst, &ofin, NULL) &&
fr_matchicmpqueryreply(is->is_v, is, icmp,
fin->fin_rev)) {
ips_stats.iss_hits++;
is->is_icmppkts++;
is->is_bytes += ip->ip_len;
fr = is->is_rule;
break;
}
RWLOCK_EXIT(&ipf_state);
return fr;
case IPPROTO_TCP :
case IPPROTO_UDP :
if (fin->fin_plen < ICMPERR_MAXPKTLEN)
return NULL;
break;
default :
return NULL;
}
tcp = (tcphdr_t *)((char *)oip + ohlen);
dport = tcp->th_dport;
sport = tcp->th_sport;
hv = (pr = oip->ip_p);
src.in4 = oip->ip_src;
hv += src.in4.s_addr;
dst.in4 = oip->ip_dst;
hv += dst.in4.s_addr;
hv += dport;
hv += sport;
hv %= fr_statesize;
READ_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_hnext) {
/*
* 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. Only the
* ports are known to be present and can be even if the
* short flag is set.
*/
if ((is->is_p == pr) && (is->is_v == 4) &&
(is->is_icmppkts < is->is_pkts) &&
fr_matchsrcdst(is, src, dst, &ofin, tcp)) {
fr = is->is_rule;
ips_stats.iss_hits++;
is->is_icmppkts++;
is->is_bytes += fin->fin_plen;
/*
* we deliberately do not touch the timeouts
* for the accompanying state table entry.
* It remains to be seen if that is correct. XXX
*/
break;
}
}
RWLOCK_EXIT(&ipf_state);
return fr;
}
/*
* Move a state hash table entry from its old location at is->is_hv to
* its new location, indexed by hv % fr_statesize.
*/
static void fr_ipsmove(isp, is, hv)
ipstate_t **isp, *is;
u_int hv;
{
u_int hvm;
hvm = is->is_hv;
/*
* Remove the hash from the old location...
*/
if (is->is_hnext)
is->is_hnext->is_phnext = isp;
*isp = is->is_hnext;
if (ips_table[hvm] == NULL)
ips_stats.iss_inuse--;
/*
* ...and put the hash in the new one.
*/
hvm = hv % fr_statesize;
is->is_hv = hvm;
isp = &ips_table[hvm];
if (*isp)
(*isp)->is_phnext = &is->is_hnext;
else
ips_stats.iss_inuse++;
is->is_phnext = isp;
is->is_hnext = *isp;
*isp = is;
}
/*
* Check if a packet has a registered state.
*/
frentry_t *fr_checkstate(ip, fin)
ip_t *ip;
fr_info_t *fin;
{
union i6addr dst, src;
register ipstate_t *is, **isp;
register u_char pr;
u_int hv, hvm, hlen, tryagain, pass, v;
struct icmp *ic;
frentry_t *fr;
tcphdr_t *tcp;
int rev;
if ((ips_list == NULL) || (fin->fin_off != 0) || fr_state_lock ||
(fin->fin_fl & FI_SHORT))
return NULL;
is = NULL;
hlen = fin->fin_hlen;
tcp = (tcphdr_t *)((char *)ip + hlen);
ic = (struct icmp *)tcp;
hv = (pr = fin->fin_fi.fi_p);
src = fin->fin_fi.fi_src;
dst = fin->fin_fi.fi_dst;
hv += src.in4.s_addr;
hv += dst.in4.s_addr;
/*
* Search the hash table for matching packet header info.
* At the bottom of this switch statement, the following is expected:
* is == NULL, no lock on ipf_state is held.
* is != NULL, a lock on ipf_state is held.
*/
v = fin->fin_fi.fi_v;
#ifdef USE_INET6
if (v == 6) {
hv += fin->fin_fi.fi_src.i6[1];
hv += fin->fin_fi.fi_src.i6[2];
hv += fin->fin_fi.fi_src.i6[3];
if ((fin->fin_p == IPPROTO_ICMPV6) &&
IN6_IS_ADDR_MULTICAST(&fin->fin_fi.fi_dst.in6)) {
hv -= dst.in4.s_addr;
} else {
hv += fin->fin_fi.fi_dst.i6[1];
hv += fin->fin_fi.fi_dst.i6[2];
hv += fin->fin_fi.fi_dst.i6[3];
}
}
#endif
switch (fin->fin_p)
{
#ifdef USE_INET6
case IPPROTO_ICMPV6 :
tcp = NULL;
tryagain = 0;
if (v == 6) {
if ((ic->icmp_type == ICMP6_ECHO_REQUEST) ||
(ic->icmp_type == ICMP6_ECHO_REPLY)) {
hv += ic->icmp_id;
hv += ic->icmp_seq;
}
}
READ_ENTER(&ipf_state);
icmp6again:
hvm = hv % fr_statesize;
for (isp = &ips_table[hvm]; (is = *isp); isp = &is->is_hnext)
if ((is->is_p == pr) && (is->is_v == v) &&
fr_matchsrcdst(is, src, dst, fin, NULL) &&
fr_matchicmpqueryreply(v, is, ic, fin->fin_rev)) {
rev = fin->fin_rev;
if (is->is_frage[rev] != 0)
is->is_age = is->is_frage[rev];
else if (rev != 0)
is->is_age = fr_icmpacktimeout;
else
is->is_age = fr_icmptimeout;
break;
}
if (is != NULL) {
if (tryagain && !(is->is_flags & FI_W_DADDR)) {
hv += fin->fin_fi.fi_src.i6[0];
hv += fin->fin_fi.fi_src.i6[1];
hv += fin->fin_fi.fi_src.i6[2];
hv += fin->fin_fi.fi_src.i6[3];
fr_ipsmove(isp, is, hv);
MUTEX_DOWNGRADE(&ipf_state);
}
break;
}
RWLOCK_EXIT(&ipf_state);
/*
* No matching icmp state entry. Perhaps this is a
* response to another state entry.
*/
if ((ips_wild != 0) && (v == 6) && (tryagain == 0) &&
!IN6_IS_ADDR_MULTICAST(&fin->fin_fi.fi_src.in6)) {
hv -= fin->fin_fi.fi_src.i6[0];
hv -= fin->fin_fi.fi_src.i6[1];
hv -= fin->fin_fi.fi_src.i6[2];
hv -= fin->fin_fi.fi_src.i6[3];
tryagain = 1;
WRITE_ENTER(&ipf_state);
goto icmp6again;
}
fr = fr_checkicmp6matchingstate((ip6_t *)ip, fin);
if (fr)
return fr;
break;
#endif
case IPPROTO_ICMP :
tcp = NULL;
if (v == 4) {
hv += ic->icmp_id;
hv += ic->icmp_seq;
}
hvm = hv % fr_statesize;
READ_ENTER(&ipf_state);
for (isp = &ips_table[hvm]; (is = *isp); isp = &is->is_hnext)
if ((is->is_p == pr) && (is->is_v == v) &&
fr_matchsrcdst(is, src, dst, fin, NULL) &&
fr_matchicmpqueryreply(v, is, ic, fin->fin_rev)) {
rev = fin->fin_rev;
if (is->is_frage[rev] != 0)
is->is_age = is->is_frage[rev];
else if (fin->fin_rev)
is->is_age = fr_icmpacktimeout;
else
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 :
/*
* Just plain ignore RST flag set with either FIN or SYN.
*/
if ((tcp->th_flags & TH_RST) &&
((tcp->th_flags & (TH_FIN|TH_SYN|TH_RST)) != TH_RST))
break;
case IPPROTO_UDP :
{
register u_short dport, sport;
dport = tcp->th_dport;
sport = tcp->th_sport;
tryagain = 0;
hv += dport;
hv += sport;
READ_ENTER(&ipf_state);
retry_tcpudp:
hvm = hv % fr_statesize;
for (isp = &ips_table[hvm]; (is = *isp); isp = &is->is_hnext)
if ((is->is_p == pr) && (is->is_v == v) &&
fr_matchsrcdst(is, src, dst, fin, tcp)) {
rev = fin->fin_rev;
if ((pr == IPPROTO_TCP)) {
if (!fr_tcpstate(is, fin, ip, tcp))
is = NULL;
} else if ((pr == IPPROTO_UDP)) {
if (is->is_frage[rev] != 0)
is->is_age = is->is_frage[rev];
else if (fin->fin_rev)
is->is_age = fr_udpacktimeout;
else
is->is_age = fr_udptimeout;
}
break;
}
if (is != NULL) {
if (tryagain &&
!(is->is_flags & (FI_WILDP|FI_WILDA))) {
hv += dport;
hv += sport;
fr_ipsmove(isp, is, hv);
MUTEX_DOWNGRADE(&ipf_state);
}
break;
}
RWLOCK_EXIT(&ipf_state);
if (!tryagain && ips_wild) {
hv -= dport;
hv -= sport;
tryagain = 1;
WRITE_ENTER(&ipf_state);
goto retry_tcpudp;
}
break;
}
default :
tcp = NULL;
hv %= fr_statesize;
READ_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_hnext) {
if ((is->is_p == pr) && (is->is_v == v) &&
fr_matchsrcdst(is, src, dst, fin, NULL)) {
rev = fin->fin_rev;
if (is->is_frage[rev] != 0)
is->is_age = is->is_frage[rev];
else
is->is_age = fr_udptimeout;
break;
}
}
if (is == NULL) {
RWLOCK_EXIT(&ipf_state);
}
break;
}
if (is == NULL) {
ATOMIC_INCL(ips_stats.iss_miss);
return NULL;
}
MUTEX_ENTER(&is->is_lock);
is->is_bytes += fin->fin_plen;
ips_stats.iss_hits++;
is->is_pkts++;
MUTEX_EXIT(&is->is_lock);
fr = is->is_rule;
fin->fin_rule = is->is_rulen;
if (fr != NULL) {
fin->fin_group = fr->fr_group;
fin->fin_icode = fr->fr_icode;
}
fin->fin_fr = fr;
pass = is->is_pass;
RWLOCK_EXIT(&ipf_state);
if ((fin->fin_fl & FI_FRAG) && (pass & FR_KEEPFRAG))
ipfr_newfrag(ip, fin);
#ifndef _KERNEL
if ((tcp != NULL) && (tcp->th_flags & TCP_CLOSE))
fr_delstate(is);
#endif
return fr;
}
/*
* Sync. state entries. If interfaces come or go or just change position,
* this is needed.
*/
void ip_statesync(ifp)
void *ifp;
{
register ipstate_t *is;
int i;
WRITE_ENTER(&ipf_state);
for (is = ips_list; is; is = is->is_next) {
for (i = 0; i < 4; i++) {
if (is->is_ifp[i] == ifp) {
is->is_ifp[i] = GETUNIT(is->is_ifname[i],
is->is_v);
if (!is->is_ifp[i])
is->is_ifp[i] = (void *)-1;
}
}
}
RWLOCK_EXIT(&ipf_state);
}
/*
* Must always be called with fr_ipfstate held as a write lock.
*/
static void fr_delstate(is)
ipstate_t *is;
{
frentry_t *fr;
if (is->is_flags & (FI_WILDP|FI_WILDA))
ips_wild--;
if (is->is_next)
is->is_next->is_pnext = is->is_pnext;
*is->is_pnext = is->is_next;
if (is->is_hnext)
is->is_hnext->is_phnext = is->is_phnext;
*is->is_phnext = is->is_hnext;
if (ips_table[is->is_hv] == NULL)
ips_stats.iss_inuse--;
if (is->is_me)
*is->is_me = NULL;
fr = is->is_rule;
if (fr != NULL) {
fr->fr_ref--;
if (fr->fr_ref == 0) {
KFREE(fr);
}
}
#ifdef _KERNEL
MUTEX_DESTROY(&is->is_lock);
#endif
KFREE(is);
ips_num--;
}
/*
* Free memory in use by all state info. kept.
*/
void fr_stateunload()
{
register ipstate_t *is;
WRITE_ENTER(&ipf_state);
while ((is = ips_list))
fr_delstate(is);
ips_stats.iss_inuse = 0;
ips_num = 0;
RWLOCK_EXIT(&ipf_state);
if (ips_table)
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 ipstate_t *is, **isp;
#if defined(_KERNEL) && !SOLARIS
int s;
#endif
SPL_NET(s);
WRITE_ENTER(&ipf_state);
for (isp = &ips_list; (is = *isp); )
if (is->is_age && !--is->is_age) {
if (is->is_p == IPPROTO_TCP)
ips_stats.iss_fin++;
else
ips_stats.iss_expire++;
#ifdef IPFILTER_LOG
ipstate_log(is, ISL_EXPIRE);
#endif
fr_delstate(is);
} else
isp = &is->is_next;
if (fr_state_doflush) {
(void) fr_state_flush(2, 0);
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)
*
* Rewritten by Arjan de Vet <Arjan.deVet@adv.iae.nl>, 2000-07-29:
*
* - (try to) base state transitions on real evidence only,
* i.e. packets that are sent and have been received by ipfilter;
* diagram 18.12 of TCP/IP volume 1 by W. Richard Stevens was used.
*
* - deal with half-closed connections correctly;
*
* - store the state of the source in state[0] such that ipfstat
* displays the state as source/dest instead of dest/source; the calls
* to fr_tcp_age have been changed accordingly.
*
* Parameters:
*
* state[0] = state of source (host that initiated connection)
* state[1] = state of dest (host that accepted the connection)
*
* dir == 0 : a packet from source to dest
* dir == 1 : a packet from dest to source
*
*/
int fr_tcp_age(age, state, fin, dir, fsm)
u_long *age;
u_char *state;
fr_info_t *fin;
int dir, fsm;
{
tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
u_char flags = tcp->th_flags;
int dlen, ostate;
u_long newage;
ostate = state[1 - dir];
dlen = fin->fin_plen - 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 0;
}
newage = 0;
switch(state[dir])
{
case TCPS_CLOSED: /* 0 */
if ((flags & TH_OPENING) == TH_OPENING) {
/*
* 'dir' received an S and sends SA in response,
* CLOSED -> SYN_RECEIVED
*/
state[dir] = TCPS_SYN_RECEIVED;
newage = fr_tcptimeout;
} else if ((flags & TH_OPENING) == TH_SYN) {
/* 'dir' sent S, CLOSED -> SYN_SENT */
state[dir] = TCPS_SYN_SENT;
newage = fr_tcptimeout;
}
/*
* It is apparently possible that a hosts sends two syncs
* before the remote party is able to respond with a SA. In
* such a case the remote server sometimes ACK's the second
* sync, and then responds with a SA. The following code
* is used to prevent this ack from being blocked.
*
* We do not reset the timeout here to fr_tcptimeout because
* a connection connect timeout does not renew after every
* packet that is sent. We need to set newage to something
* to indicate the packet has passed the check for its flags
* being valid in the TCP FSM.
*/
else if ((ostate == TCPS_SYN_SENT) &&
((flags & (TH_FIN|TH_SYN|TH_RST|TH_ACK)) == TH_ACK)) {
newage = *age;
}
/*
* The next piece of code makes it possible to get
* already established connections into the state table
* after a restart or reload of the filter rules; this
* does not work when a strict 'flags S keep state' is
* used for tcp connections of course, however, use a
* lower time-out so the state disappears quickly if
* the other side does not pick it up.
*/
else if (!fsm &&
(flags & (TH_FIN|TH_SYN|TH_RST|TH_ACK)) == TH_ACK) {
/* we saw an A, guess 'dir' is in ESTABLISHED mode */
if (ostate == TCPS_CLOSED) {
state[dir] = TCPS_ESTABLISHED;
newage = fr_tcptimeout;
} else if (ostate == TCPS_ESTABLISHED) {
state[dir] = TCPS_ESTABLISHED;
newage = fr_tcpidletimeout;
}
}
/*
* TODO: besides regular ACK packets we can have other
* packets as well; it is yet to be determined how we
* should initialize the states in those cases
*/
break;
case TCPS_LISTEN: /* 1 */
/* NOT USED */
break;
case TCPS_SYN_SENT: /* 2 */
if ((flags & ~(TH_ECN|TH_CWR)) == TH_SYN) {
/*
* A retransmitted SYN packet. We do not reset the
* timeout here to fr_tcptimeout because a connection
* connect timeout does not renew after every packet
* that is sent. We need to set newage to something
* to indicate the packet has passed the check for its
* flags being valid in the TCP FSM.
*/
newage = *age;
} else if ((flags & (TH_SYN|TH_FIN|TH_ACK)) == TH_ACK) {
/*
* We see an A from 'dir' which is in SYN_SENT
* state: 'dir' sent an A in response to an SA
* which it received, SYN_SENT -> ESTABLISHED
*/
state[dir] = TCPS_ESTABLISHED;
newage = fr_tcpidletimeout;
} else if (flags & TH_FIN) {
/*
* We see an F from 'dir' which is in SYN_SENT
* state and wants to close its side of the
* connection; SYN_SENT -> FIN_WAIT_1
*/
state[dir] = TCPS_FIN_WAIT_1;
newage = fr_tcpidletimeout; /* or fr_tcptimeout? */
} else if ((flags & TH_OPENING) == TH_OPENING) {
/*
* We see an SA from 'dir' which is already in
* SYN_SENT state, this means we have a
* simultaneous open; SYN_SENT -> SYN_RECEIVED
*/
state[dir] = TCPS_SYN_RECEIVED;
newage = fr_tcptimeout;
}
break;
case TCPS_SYN_RECEIVED: /* 3 */
if ((flags & (TH_SYN|TH_FIN|TH_ACK)) == TH_ACK) {
/*
* We see an A from 'dir' which was in SYN_RECEIVED
* state so it must now be in established state,
* SYN_RECEIVED -> ESTABLISHED
*/
state[dir] = TCPS_ESTABLISHED;
newage = fr_tcpidletimeout;
} else if ((flags & ~(TH_ECN|TH_CWR)) == TH_OPENING) {
/*
* We see an SA from 'dir' which is already in
* SYN_RECEIVED state.
*/
newage = fr_tcptimeout;
} else if (flags & TH_FIN) {
/*
* We see an F from 'dir' which is in SYN_RECEIVED
* state and wants to close its side of the connection;
* SYN_RECEIVED -> FIN_WAIT_1
*/
state[dir] = TCPS_FIN_WAIT_1;
newage = fr_tcpidletimeout;
}
break;
case TCPS_ESTABLISHED: /* 4 */
if (flags & TH_FIN) {
/*
* 'dir' closed its side of the connection; this
* gives us a half-closed connection;
* ESTABLISHED -> FIN_WAIT_1
*/
state[dir] = TCPS_FIN_WAIT_1;
newage = fr_tcphalfclosed;
} else if (flags & TH_ACK) {
/* an ACK, should we exclude other flags here? */
if (ostate == TCPS_FIN_WAIT_1) {
/*
* We know the other side did an active close,
* so we are ACKing the recvd FIN packet (does
* the window matching code guarantee this?)
* and go into CLOSE_WAIT state; this gives us
* a half-closed connection
*/
state[dir] = TCPS_CLOSE_WAIT;
newage = fr_tcphalfclosed;
} else if (ostate < TCPS_CLOSE_WAIT)
/*
* Still a fully established connection,
* reset timeout
*/
newage = fr_tcpidletimeout;
}
break;
case TCPS_CLOSE_WAIT: /* 5 */
if (flags & TH_FIN) {
/*
* Application closed and 'dir' sent a FIN, we're now
* going into LAST_ACK state
*/
newage = fr_tcplastack;
state[dir] = TCPS_LAST_ACK;
} else {
/*
* We remain in CLOSE_WAIT because the other side has
* closed already and we did not close our side yet;
* reset timeout
*/
newage = fr_tcphalfclosed;
}
break;
case TCPS_FIN_WAIT_1: /* 6 */
if ((flags & TH_ACK) && ostate > TCPS_CLOSE_WAIT) {
/*
* If the other side is not active anymore it has sent
* us a FIN packet that we are ack'ing now with an ACK;
* this means both sides have now closed the connection
* and we go into TIME_WAIT
*/
/*
* XXX: how do we know we really are ACKing the FIN
* packet here? does the window code guarantee that?
*/
state[dir] = TCPS_TIME_WAIT;
newage = fr_tcptimeout;
} else
/*
* We closed our side of the connection already but the
* other side is still active (ESTABLISHED/CLOSE_WAIT);
* continue with this half-closed connection
*/
newage = fr_tcphalfclosed;
break;
case TCPS_CLOSING: /* 7 */
/* NOT USED */
break;
case TCPS_LAST_ACK: /* 8 */
if (flags & TH_ACK) {
if ((flags & TH_PUSH) || dlen)
/*
* There is still data to be delivered, reset
* timeout
*/
newage = fr_tcplastack;
else
newage = *age;
}
/*
* We cannot detect when we go out of LAST_ACK state to CLOSED
* because that is based on the reception of ACK packets;
* ipfilter can only detect that a packet has been sent by a
* host
*/
break;
case TCPS_FIN_WAIT_2: /* 9 */
/* NOT USED */
break;
case TCPS_TIME_WAIT: /* 10 */
newage = fr_tcptimeout; /* default 4 mins */
/* we're in 2MSL timeout now */
break;
}
if (newage != 0) {
*age = newage;
return 0;
}
return -1;
}
#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 + is->is_icmppkts;
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_v = is->is_v;
ipsl.isl_flags = is->is_flags;
ipsl.isl_rulen = is->is_rulen;
ipsl.isl_group = is->is_group;
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 if (ipsl.isl_p == IPPROTO_ICMPV6) {
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;
if (ipllog(IPL_LOGSTATE, NULL, items, sizes, types, 1)) {
ATOMIC_INCL(ips_stats.iss_logged);
} else {
ATOMIC_INCL(ips_stats.iss_logfail);
}
}
#endif
#ifdef USE_INET6
frentry_t *fr_checkicmp6matchingstate(ip, fin)
ip6_t *ip;
fr_info_t *fin;
{
register ipstate_t *is, **isp;
register u_short sport, dport;
register u_char pr;
struct icmp6_hdr *ic, *oic;
union i6addr dst, src;
u_short savelen;
fr_info_t ofin;
tcphdr_t *tcp;
frentry_t *fr;
ip6_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 ((fin->fin_v != 6) || (fin->fin_plen < ICMP6ERR_MINPKTLEN))
return NULL;
ic = (struct icmp6_hdr *)fin->fin_dp;
type = ic->icmp6_type;
/*
* If it's not an error type, then return
*/
if ((type != ICMP6_DST_UNREACH) && (type != ICMP6_PACKET_TOO_BIG) &&
(type != ICMP6_TIME_EXCEEDED) && (type != ICMP6_PARAM_PROB))
return NULL;
oip = (ip6_t *)((char *)ic + ICMPERR_ICMPHLEN);
if (fin->fin_plen < sizeof(*oip))
return NULL;
if ((oip->ip6_nxt != IPPROTO_TCP) && (oip->ip6_nxt != IPPROTO_UDP) &&
(oip->ip6_nxt != IPPROTO_ICMPV6))
return NULL;
bzero((char *)&ofin, sizeof(ofin));
ofin.fin_out = !fin->fin_out;
ofin.fin_ifp = fin->fin_ifp;
ofin.fin_mp = NULL;
ofin.fin_v = 6;
#if SOLARIS
ofin.fin_qfm = NULL;
#endif
/*
* We make a fin entry to be able to feed it to
* matchsrcdst. Note that not all fields are necessary
* 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->ip6_plen;
oip->ip6_plen = ip->ip6_plen - sizeof(*ip) - ICMPERR_ICMPHLEN;
fr_makefrip(sizeof(*oip), (ip_t *)oip, &ofin);
oip->ip6_plen = savelen;
if (oip->ip6_nxt == IPPROTO_ICMPV6) {
oic = (struct icmp6_hdr *)(oip + 1);
/*
* an 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 (!(oic->icmp6_type & ICMP6_INFOMSG_MASK))
return NULL;
/*
* perform a lookup of the ICMP packet in the state table
*/
hv = (pr = oip->ip6_nxt);
src.in6 = oip->ip6_src;
hv += src.in4.s_addr;
dst.in6 = oip->ip6_dst;
hv += dst.in4.s_addr;
hv += oic->icmp6_id;
hv += oic->icmp6_seq;
hv %= fr_statesize;
READ_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_hnext)
if ((is->is_p == pr) &&
(oic->icmp6_id == is->is_icmp.ics_id) &&
(oic->icmp6_seq == is->is_icmp.ics_seq) &&
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 == ICMP6_ECHO_REPLY) &&
(oic->icmp6_type == ICMP6_ECHO_REQUEST)) ||
(is->is_type - 1 == oic->icmp6_type )) {
ips_stats.iss_hits++;
is->is_pkts++;
is->is_bytes += fin->fin_plen;
return is->is_rule;
}
}
RWLOCK_EXIT(&ipf_state);
return NULL;
}
tcp = (tcphdr_t *)(oip + 1);
dport = tcp->th_dport;
sport = tcp->th_sport;
hv = (pr = oip->ip6_nxt);
src.in6 = oip->ip6_src;
hv += src.in4.s_addr;
hv += src.i6[1];
hv += src.i6[2];
hv += src.i6[3];
dst.in6 = oip->ip6_dst;
hv += dst.in4.s_addr;
hv += dst.i6[1];
hv += dst.i6[2];
hv += dst.i6[3];
hv += dport;
hv += sport;
hv %= fr_statesize;
READ_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_hnext) {
/*
* 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) && (is->is_v == 6) &&
fr_matchsrcdst(is, src, dst, &ofin, tcp)) {
fr = is->is_rule;
ips_stats.iss_hits++;
is->is_pkts++;
is->is_bytes += fin->fin_plen;
/*
* 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;
}
#endif