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freebsd-nq/sys/netinet/ip_fw.c

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/*
* Copyright (c) 1996 Alex Nash
* Copyright (c) 1993 Daniel Boulet
* Copyright (c) 1994 Ugen J.S.Antsilevich
*
* Redistribution and use in source forms, with and without modification,
* are permitted provided that this entire comment appears intact.
*
* Redistribution in binary form may occur without any restrictions.
* Obviously, it would be nice if you gave credit where credit is due
* but requiring it would be too onerous.
*
* This software is provided ``AS IS'' without any warranties of any kind.
*
* $Id: ip_fw.c,v 1.42 1996/06/25 00:22:20 alex Exp $
*/
/*
* Implement IP packet firewall
*/
#ifndef IPFIREWALL_MODULE
#include "opt_ipfw.h"
#endif
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/queue.h>
#include <sys/kernel.h>
#include <sys/time.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip_fw.h>
static int fw_debug = 1;
#ifdef IPFIREWALL_VERBOSE
static int fw_verbose = 1;
#else
static int fw_verbose = 0;
#endif
#ifdef IPFIREWALL_VERBOSE_LIMIT
static int fw_verbose_limit = IPFIREWALL_VERBOSE_LIMIT;
#else
static int fw_verbose_limit = 0;
#endif
LIST_HEAD (ip_fw_head, ip_fw_chain) ip_fw_chain;
#ifdef SYSCTL_NODE
SYSCTL_NODE(net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
SYSCTL_INT(net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, &fw_debug, 0, "");
SYSCTL_INT(net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, &fw_verbose, 0, "");
SYSCTL_INT(net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, &fw_verbose_limit, 0, "");
#endif
#define dprintf(a) if (!fw_debug); else printf a
#define print_ip(a) printf("%ld.%ld.%ld.%ld",(ntohl(a.s_addr)>>24)&0xFF,\
(ntohl(a.s_addr)>>16)&0xFF,\
(ntohl(a.s_addr)>>8)&0xFF,\
(ntohl(a.s_addr))&0xFF);
#define dprint_ip(a) if (!fw_debug); else print_ip(a)
static int add_entry __P((struct ip_fw_head *chainptr, struct ip_fw *frwl));
static int del_entry __P((struct ip_fw_head *chainptr, struct ip_fw *frwl));
static int zero_entry __P((struct mbuf *m));
static struct ip_fw *
check_ipfw_struct __P(( struct mbuf *m));
static int ipopts_match __P((struct ip *ip, struct ip_fw *f));
static int port_match __P((u_short *portptr, int nports, u_short port,
int range_flag));
static int tcpflg_match __P((struct tcphdr *tcp, struct ip_fw *f));
static int icmptype_match __P((struct icmp * icmp, struct ip_fw * f));
static void ipfw_report __P((char *txt, int rule, struct ip *ip, int counter));
#ifdef IPFIREWALL_MODULE
static ip_fw_chk_t *old_chk_ptr;
static ip_fw_ctl_t *old_ctl_ptr;
#endif
static int ip_fw_chk __P((struct ip **pip, int hlen, struct ifnet *rif,
int dir, struct mbuf **m));
static int ip_fw_ctl __P((int stage, struct mbuf **mm));
/*
* Returns 1 if the port is matched by the vector, 0 otherwise
*/
static inline int
port_match(u_short *portptr, int nports, u_short port, int range_flag)
{
if (!nports)
return 1;
if (range_flag) {
if (portptr[0] <= port && port <= portptr[1]) {
return 1;
}
nports -= 2;
portptr += 2;
}
while (nports-- > 0) {
if (*portptr++ == port) {
return 1;
}
}
return 0;
}
static int
tcpflg_match(struct tcphdr *tcp, struct ip_fw *f)
{
u_char flg_set, flg_clr;
if ((f->fw_tcpf & IP_FW_TCPF_ESTAB) &&
(tcp->th_flags & (IP_FW_TCPF_RST | IP_FW_TCPF_ACK)))
return 1;
flg_set = tcp->th_flags & f->fw_tcpf;
flg_clr = tcp->th_flags & f->fw_tcpnf;
if (flg_set != f->fw_tcpf)
return 0;
if (flg_clr)
return 0;
return 1;
}
static int
icmptype_match(struct icmp *icmp, struct ip_fw *f)
{
int type;
if (!(f->fw_flg & IP_FW_F_ICMPBIT))
return(1);
type = icmp->icmp_type;
/* check for matching type in the bitmap */
if (f->fw_icmptypes[type / (sizeof(unsigned) * 8)] &
(1U << (type % (8 * sizeof(unsigned)))))
return(1);
return(0); /* no match */
}
static int
ipopts_match(struct ip *ip, struct ip_fw *f)
{
register u_char *cp;
int opt, optlen, cnt;
u_char opts, nopts, nopts_sve;
cp = (u_char *)(ip + 1);
cnt = (ip->ip_hl << 2) - sizeof (struct ip);
opts = f->fw_ipopt;
nopts = nopts_sve = f->fw_ipnopt;
for (; cnt > 0; cnt -= optlen, cp += optlen) {
opt = cp[IPOPT_OPTVAL];
if (opt == IPOPT_EOL)
break;
if (opt == IPOPT_NOP)
optlen = 1;
else {
optlen = cp[IPOPT_OLEN];
if (optlen <= 0 || optlen > cnt) {
return 0; /*XXX*/
}
}
switch (opt) {
default:
break;
case IPOPT_LSRR:
opts &= ~IP_FW_IPOPT_LSRR;
nopts &= ~IP_FW_IPOPT_LSRR;
break;
case IPOPT_SSRR:
opts &= ~IP_FW_IPOPT_SSRR;
nopts &= ~IP_FW_IPOPT_SSRR;
break;
case IPOPT_RR:
opts &= ~IP_FW_IPOPT_RR;
nopts &= ~IP_FW_IPOPT_RR;
break;
case IPOPT_TS:
opts &= ~IP_FW_IPOPT_TS;
nopts &= ~IP_FW_IPOPT_TS;
break;
}
if (opts == nopts)
break;
}
if (opts == 0 && nopts == nopts_sve)
return 1;
else
return 0;
}
static void
ipfw_report(char *txt, int rule, struct ip *ip, int counter)
{
struct tcphdr *tcp = (struct tcphdr *) ((u_long *) ip + ip->ip_hl);
struct udphdr *udp = (struct udphdr *) ((u_long *) ip + ip->ip_hl);
struct icmp *icmp = (struct icmp *) ((u_long *) ip + ip->ip_hl);
if (!fw_verbose)
return;
if (fw_verbose_limit != 0 && counter > fw_verbose_limit)
return;
printf("ipfw: %d %s ",rule, txt);
switch (ip->ip_p) {
case IPPROTO_TCP:
printf("TCP ");
print_ip(ip->ip_src);
printf(":%d ", ntohs(tcp->th_sport));
print_ip(ip->ip_dst);
printf(":%d", ntohs(tcp->th_dport));
break;
case IPPROTO_UDP:
printf("UDP ");
print_ip(ip->ip_src);
printf(":%d ", ntohs(udp->uh_sport));
print_ip(ip->ip_dst);
printf(":%d", ntohs(udp->uh_dport));
break;
case IPPROTO_ICMP:
printf("ICMP:%u.%u ", icmp->icmp_type, icmp->icmp_code);
print_ip(ip->ip_src);
printf(" ");
print_ip(ip->ip_dst);
break;
default:
printf("P:%d ", ip->ip_p);
print_ip(ip->ip_src);
printf(" ");
print_ip(ip->ip_dst);
break;
}
if ((ip->ip_off & IP_OFFMASK))
printf(" Fragment = %d",ip->ip_off & IP_OFFMASK);
printf("\n");
}
/*
* Returns 1 if it should be accepted, 0 otherwise.
*/
static int
ip_fw_chk(struct ip **pip, int hlen, struct ifnet *rif, int dir, struct mbuf **m)
{
struct ip_fw_chain *chain;
register struct ip_fw *f = NULL;
struct ip *ip = *pip;
struct tcphdr *tcp = (struct tcphdr *) ((u_long *) ip + ip->ip_hl);
struct udphdr *udp = (struct udphdr *) ((u_long *) ip + ip->ip_hl);
struct icmp *icmp = (struct icmp *) ((u_long *) ip + ip->ip_hl);
struct ifaddr *ia = NULL, *ia_p;
struct in_addr src, dst, ia_i;
u_short src_port = 0, dst_port = 0;
u_short f_prt = 0, prt, len = 0;
/*
* ... else if non-zero, highly unusual and interesting, but
* we're not going to pass it...
*/
if ((ip->ip_off & IP_OFFMASK) == 1) {
static int frag_counter = 0;
++frag_counter;
ipfw_report("Refuse", -1, ip, frag_counter);
m_freem(*m);
return 0;
}
src = ip->ip_src;
dst = ip->ip_dst;
/*
* If we got interface from which packet came-store pointer to it's
* first adress
*/
if (rif != NULL)
ia = rif->if_addrlist;
/*
* Determine the protocol and extract some useful stuff
*/
switch (ip->ip_p) {
case IPPROTO_TCP:
src_port = ntohs(tcp->th_sport);
dst_port = ntohs(tcp->th_dport);
prt = IP_FW_F_TCP;
len = sizeof (*tcp);
break;
case IPPROTO_UDP:
src_port = ntohs(udp->uh_sport);
dst_port = ntohs(udp->uh_dport);
prt = IP_FW_F_UDP;
len = sizeof (*udp);
break;
case IPPROTO_ICMP:
prt = IP_FW_F_ICMP;
len = sizeof (*icmp);
break;
default:
prt = IP_FW_F_ALL;
break;
}
/* XXX Check that we have sufficient header for TCP analysis */
/*
* Go down the chain, looking for enlightment
*/
for (chain=ip_fw_chain.lh_first; chain; chain = chain->chain.le_next) {
f = chain->rule;
/* Check direction inbound */
if (!dir && !(f->fw_flg & IP_FW_F_IN))
continue;
/* Check direction outbound */
if (dir && !(f->fw_flg & IP_FW_F_OUT))
continue;
/* Fragments */
if ((f->fw_flg & IP_FW_F_FRAG) && !(ip->ip_off & IP_OFFMASK))
continue;
/* If src-addr doesn't match, not this rule. */
if ((src.s_addr & f->fw_smsk.s_addr) != f->fw_src.s_addr)
continue;
/* If dest-addr doesn't match, not this rule. */
if ((dst.s_addr & f->fw_dmsk.s_addr) != f->fw_dst.s_addr)
continue;
/* If a i/f name was specified, and we don't know */
if ((f->fw_flg & IP_FW_F_IFNAME) && !rif)
continue;
/* If a i/f name was specified, check it */
if ((f->fw_flg & IP_FW_F_IFNAME) && f->fw_via_name[0]) {
/* Not same unit, don't match */
if (!(f->fw_flg & IP_FW_F_IFUWILD) && rif->if_unit != f->fw_via_unit)
continue;
/* Not same name */
if (strncmp(rif->if_name, f->fw_via_name, FW_IFNLEN))
continue;
}
/* If a i/f addr was specified, check it */
if (!(f->fw_flg & IP_FW_F_IFNAME) && f->fw_via_ip.s_addr) {
int match = 0;
for (ia_p = ia; ia_p != NULL; ia_p = ia_p->ifa_next) {
if ((ia_p->ifa_addr == NULL))
continue;
if (ia_p->ifa_addr->sa_family != AF_INET)
continue;
ia_i.s_addr =
((struct sockaddr_in *)
(ia_p->ifa_addr))->sin_addr.s_addr;
if (ia_i.s_addr != f->fw_via_ip.s_addr)
continue;
match = 1;
break;
}
if (!match)
continue;
}
/*
* Check IP options
*/
if (f->fw_ipopt != f->fw_ipnopt)
if (!ipopts_match(ip, f))
continue;
/*
* Check protocol
*/
f_prt = f->fw_flg & IP_FW_F_KIND;
/* If wildcard, match */
if (f_prt == IP_FW_F_ALL)
goto got_match;
/* If different, dont match */
if (prt != f_prt)
continue;
/* ICMP, done */
if (prt == IP_FW_F_ICMP) {
if (!icmptype_match(icmp, f))
continue;
goto got_match;
}
/* Check TCP flags and TCP/UDP ports only if packet is not fragment */
if (!(ip->ip_off & IP_OFFMASK)) {
/* TCP, a little more checking */
if (prt == IP_FW_F_TCP &&
(f->fw_tcpf != f->fw_tcpnf) &&
(!tcpflg_match(tcp, f)))
continue;
if (!port_match(&f->fw_pts[0], f->fw_nsp,
src_port, f->fw_flg & IP_FW_F_SRNG))
continue;
if (!port_match(&f->fw_pts[f->fw_nsp], f->fw_ndp,
dst_port, f->fw_flg & IP_FW_F_DRNG))
continue;
}
got_match:
f->fw_pcnt++;
f->fw_bcnt+=ip->ip_len;
f->timestamp = time.tv_sec;
if (f->fw_flg & IP_FW_F_PRN) {
if (f->fw_flg & IP_FW_F_ACCEPT)
ipfw_report("Allow", f->fw_number, ip, f->fw_pcnt);
else if (f->fw_flg & IP_FW_F_COUNT)
ipfw_report("Count", f->fw_number, ip, f->fw_pcnt);
else
ipfw_report("Deny", f->fw_number, ip, f->fw_pcnt);
}
if (f->fw_flg & IP_FW_F_ACCEPT)
return 1;
if (f->fw_flg & IP_FW_F_COUNT)
continue;
break;
}
/*
* Don't icmp outgoing packets at all
*/
if (f != NULL && !dir) {
/*
* Do not ICMP reply to icmp packets....:) or to packets
* rejected by entry without the special ICMP reply flag.
*/
if ((f_prt != IP_FW_F_ICMP) && (f->fw_flg & IP_FW_F_ICMPRPL)) {
if (f_prt == IP_FW_F_ALL)
icmp_error(*m, ICMP_UNREACH,
ICMP_UNREACH_HOST, 0L, 0);
else
icmp_error(*m, ICMP_UNREACH,
ICMP_UNREACH_PORT, 0L, 0);
return 0;
}
}
m_freem(*m);
return 0;
}
static int
add_entry(struct ip_fw_head *chainptr, struct ip_fw *frwl)
{
struct ip_fw *ftmp = 0;
struct ip_fw_chain *fwc = 0, *fcp, *fcpl = 0;
u_short nbr = 0;
int s;
fwc = malloc(sizeof *fwc, M_IPFW, M_DONTWAIT);
ftmp = malloc(sizeof *ftmp, M_IPFW, M_DONTWAIT);
if (!fwc || !ftmp) {
dprintf(("ip_fw_ctl: malloc said no\n"));
if (fwc) free(fwc, M_IPFW);
if (ftmp) free(ftmp, M_IPFW);
return (ENOSPC);
}
bcopy(frwl, ftmp, sizeof(struct ip_fw));
ftmp->fw_pcnt = 0L;
ftmp->fw_bcnt = 0L;
fwc->rule = ftmp;
s = splnet();
if (!chainptr->lh_first) {
LIST_INSERT_HEAD(chainptr, fwc, chain);
splx(s);
return(0);
} else if (ftmp->fw_number == (u_short)-1) {
if (fwc) free(fwc, M_IPFW);
if (ftmp) free(ftmp, M_IPFW);
splx(s);
return (EINVAL);
}
/* If entry number is 0, find highest numbered rule and add 100 */
if (ftmp->fw_number == 0) {
for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next) {
if (fcp->rule->fw_number != (u_short)-1)
nbr = fcp->rule->fw_number;
else
break;
}
if (nbr < (u_short)-1 - 100)
nbr += 100;
ftmp->fw_number = nbr;
}
/* Got a valid number; now insert it, keeping the list ordered */
for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next) {
if (fcp->rule->fw_number > ftmp->fw_number) {
if (fcpl) {
LIST_INSERT_AFTER(fcpl, fwc, chain);
} else {
LIST_INSERT_HEAD(chainptr, fwc, chain);
}
break;
} else {
fcpl = fcp;
}
}
splx(s);
return (0);
}
static int
del_entry(struct ip_fw_head *chainptr, struct ip_fw *frwl)
{
struct ip_fw_chain *fcp;
int s;
s = splnet();
fcp = chainptr->lh_first;
if (frwl->fw_number != (u_short)-1) {
for (; fcp; fcp = fcp->chain.le_next) {
if (fcp->rule->fw_number == frwl->fw_number) {
LIST_REMOVE(fcp, chain);
splx(s);
free(fcp->rule, M_IPFW);
free(fcp, M_IPFW);
return 0;
}
}
}
splx(s);
return (EINVAL);
}
static int
zero_entry(struct mbuf *m)
{
struct ip_fw *frwl;
struct ip_fw_chain *fcp;
int s;
if (m) {
frwl = check_ipfw_struct(m);
if (!frwl)
return(EINVAL);
}
else
frwl = NULL;
/*
* It's possible to insert multiple chain entries with the
* same number, so we don't stop after finding the first
* match if zeroing a specific entry.
*/
s = splnet();
for (fcp = ip_fw_chain.lh_first; fcp; fcp = fcp->chain.le_next)
if (!frwl || frwl->fw_number == fcp->rule->fw_number) {
fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0;
fcp->rule->timestamp = 0;
}
splx(s);
return(0);
}
static struct ip_fw *
check_ipfw_struct(struct mbuf *m)
{
struct ip_fw *frwl;
if (m->m_len != sizeof(struct ip_fw)) {
dprintf(("ip_fw_ctl: len=%d, want %d\n", m->m_len,
sizeof(struct ip_fw)));
return (NULL);
}
frwl = mtod(m, struct ip_fw *);
if ((frwl->fw_flg & ~IP_FW_F_MASK) != 0) {
dprintf(("ip_fw_ctl: undefined flag bits set (flags=%x)\n",
frwl->fw_flg));
return (NULL);
}
/* If neither In nor Out, then both */
if (!(frwl->fw_flg & (IP_FW_F_IN | IP_FW_F_OUT)))
frwl->fw_flg |= IP_FW_F_IN | IP_FW_F_OUT;
if ((frwl->fw_flg & IP_FW_F_SRNG) && frwl->fw_nsp < 2) {
dprintf(("ip_fw_ctl: src range set but n_src_p=%d\n",
frwl->fw_nsp));
return (NULL);
}
if ((frwl->fw_flg & IP_FW_F_DRNG) && frwl->fw_ndp < 2) {
dprintf(("ip_fw_ctl: dst range set but n_dst_p=%d\n",
frwl->fw_ndp));
return (NULL);
}
if (frwl->fw_nsp + frwl->fw_ndp > IP_FW_MAX_PORTS) {
dprintf(("ip_fw_ctl: too many ports (%d+%d)\n",
frwl->fw_nsp, frwl->fw_ndp));
return (NULL);
}
/*
* ICMP and ALL protocols don't check port ranges
*/
if ((frwl->fw_flg & IP_FW_F_KIND) != IP_FW_F_TCP &&
(frwl->fw_flg & IP_FW_F_KIND) != IP_FW_F_UDP &&
(frwl->fw_nsp || frwl->fw_ndp)) {
dprintf(("ip_fw_ctl: invalid protocol/port combination\n"));
return(NULL);
}
/*
* Rather than modify the entry to make such entries work,
* we reject this rule and require user level utilities
* to enforce whatever policy they deem appropriate.
*/
if ((frwl->fw_src.s_addr & (~frwl->fw_smsk.s_addr)) ||
(frwl->fw_dst.s_addr & (~frwl->fw_dmsk.s_addr))) {
dprintf(("ip_fw_ctl: rule never matches\n"));
return(NULL);
}
return frwl;
}
static int
ip_fw_ctl(int stage, struct mbuf **mm)
{
int error;
struct mbuf *m;
if (stage == IP_FW_GET) {
struct ip_fw_chain *fcp = ip_fw_chain.lh_first;
*mm = m = m_get(M_WAIT, MT_SOOPTS);
for (; fcp; fcp = fcp->chain.le_next) {
memcpy(m->m_data, fcp->rule, sizeof *(fcp->rule));
m->m_len = sizeof *(fcp->rule);
m->m_next = m_get(M_WAIT, MT_SOOPTS);
m = m->m_next;
m->m_len = 0;
}
return (0);
}
m = *mm;
/* only allow get calls if secure mode > 2 */
if (securelevel > 2) {
if (m) (void)m_free(m);
return(EPERM);
}
if (stage == IP_FW_FLUSH) {
while (ip_fw_chain.lh_first != NULL &&
ip_fw_chain.lh_first->rule->fw_number != (u_short)-1) {
struct ip_fw_chain *fcp = ip_fw_chain.lh_first;
int s = splnet();
LIST_REMOVE(ip_fw_chain.lh_first, chain);
splx(s);
free(fcp->rule, M_IPFW);
free(fcp, M_IPFW);
}
if (m) (void)m_free(m);
return (0);
}
if (stage == IP_FW_ZERO) {
error = zero_entry(m);
if (m) (void)m_free(m);
return (error);
}
if (m == NULL) {
printf("ip_fw_ctl: NULL mbuf ptr\n");
return (EINVAL);
}
if (stage == IP_FW_ADD || stage == IP_FW_DEL) {
struct ip_fw *frwl = check_ipfw_struct(m);
if (!frwl) {
if (m) (void)m_free(m);
return (EINVAL);
}
if (stage == IP_FW_ADD)
error = add_entry(&ip_fw_chain, frwl);
else
error = del_entry(&ip_fw_chain, frwl);
if (m) (void)m_free(m);
return error;
}
dprintf(("ip_fw_ctl: unknown request %d\n", stage));
if (m) (void)m_free(m);
return (EINVAL);
}
void
ip_fw_init(void)
{
struct ip_fw deny;
ip_fw_chk_ptr = ip_fw_chk;
ip_fw_ctl_ptr = ip_fw_ctl;
LIST_INIT(&ip_fw_chain);
bzero(&deny, sizeof deny);
deny.fw_flg = IP_FW_F_ALL;
deny.fw_number = (u_short)-1;
add_entry(&ip_fw_chain, &deny);
printf("IP firewall initialized, ");
#ifndef IPFIREWALL_VERBOSE
printf("logging disabled\n");
#else
if (fw_verbose_limit == 0)
printf("unlimited logging\n");
else
printf("logging limited to %d packets/entry\n", fw_verbose_limit);
#endif
}
#ifdef IPFIREWALL_MODULE
#include <sys/exec.h>
#include <sys/sysent.h>
#include <sys/lkm.h>
MOD_MISC(ipfw);
static int
ipfw_load(struct lkm_table *lkmtp, int cmd)
{
int s=splnet();
old_chk_ptr = ip_fw_chk_ptr;
old_ctl_ptr = ip_fw_ctl_ptr;
ip_fw_init();
splx(s);
return 0;
}
static int
ipfw_unload(struct lkm_table *lkmtp, int cmd)
{
int s=splnet();
ip_fw_chk_ptr = old_chk_ptr;
ip_fw_ctl_ptr = old_ctl_ptr;
while (ip_fw_chain.lh_first != NULL) {
struct ip_fw_chain *fcp = ip_fw_chain.lh_first;
LIST_REMOVE(ip_fw_chain.lh_first, chain);
free(fcp->rule, M_IPFW);
free(fcp, M_IPFW);
}
splx(s);
printf("IP firewall unloaded\n");
return 0;
}
int
ipfw_mod(struct lkm_table *lkmtp, int cmd, int ver)
{
DISPATCH(lkmtp, cmd, ver, ipfw_load, ipfw_unload, lkm_nullcmd);
}
#endif
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