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6d473e818c
freebsd/sys/netinet/ip_fw.c
Alexander Langer 6d473e818c Allow ICMP unreachable messages to be sent in response to ICMP query 
packets (as per Stevens volume 1 section 6.2).
1998-03-15 00:36:27 +00:00

1118 lines
27 KiB
C
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/*
* Copyright (c) 1993 Daniel Boulet
* Copyright (c) 1994 Ugen J.S.Antsilevich
* Copyright (c) 1996 Alex Nash
*
* 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 1.78 1998/02/12 00:57:04 alex Exp $
*/
/*
* Implement IP packet firewall
*/
#ifndef IPFIREWALL_MODULE
#include "opt_ipfw.h"
#include "opt_ipdivert.h"
#include "opt_inet.h"
#ifndef INET
#error IPFIREWALL requires INET.
#endif /* INET */
#endif
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip_fw.h>
#include <netinet/tcp.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#include <netinet/udp.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
static LIST_HEAD (ip_fw_head, ip_fw_chain) ip_fw_chain;
static MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's");
#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, u_short number));
static int zero_entry __P((struct mbuf *m));
static struct ip_fw *check_ipfw_struct __P((struct ip_fw *m));
static struct ip_fw *check_ipfw_mbuf __P((struct mbuf *fw));
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((struct ip_fw *f, struct ip *ip,
struct ifnet *rif, struct ifnet *oif));
#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 *oif, int ignport, struct mbuf **m));
static int ip_fw_ctl __P((int stage, struct mbuf **mm));
static char err_prefix[] = "ip_fw_ctl:";
/*
* 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 (type < IP_FW_ICMPTYPES_MAX &&
(f->fw_uar.fw_icmptypes[type / (sizeof(unsigned) * 8)] &
(1U << (type % (8 * sizeof(unsigned))))))
return(1);
return(0); /* no match */
}
static int
is_icmp_query(struct ip *ip)
{
const struct icmp *icmp;
int icmp_type;
icmp = (struct icmp *)((u_long *)ip + ip->ip_hl);
icmp_type = icmp->icmp_type;
if (icmp_type == ICMP_ECHO || icmp_type == ICMP_ROUTERSOLICIT ||
icmp_type == ICMP_TSTAMP || icmp_type == ICMP_IREQ ||
icmp_type == ICMP_MASKREQ)
return(1);
return(0);
}
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 inline int
iface_match(struct ifnet *ifp, union ip_fw_if *ifu, int byname)
{
/* Check by name or by IP address */
if (byname) {
/* Check unit number (-1 is wildcard) */
if (ifu->fu_via_if.unit != -1
&& ifp->if_unit != ifu->fu_via_if.unit)
return(0);
/* Check name */
if (strncmp(ifp->if_name, ifu->fu_via_if.name, FW_IFNLEN))
return(0);
return(1);
} else if (ifu->fu_via_ip.s_addr != 0) { /* Zero == wildcard */
struct ifaddr *ia;
for (ia = ifp->if_addrhead.tqh_first;
ia != NULL; ia = ia->ifa_link.tqe_next) {
if (ia->ifa_addr == NULL)
continue;
if (ia->ifa_addr->sa_family != AF_INET)
continue;
if (ifu->fu_via_ip.s_addr != ((struct sockaddr_in *)
(ia->ifa_addr))->sin_addr.s_addr)
continue;
return(1);
}
return(0);
}
return(1);
}
static void
ipfw_report(struct ip_fw *f, struct ip *ip,
struct ifnet *rif, struct ifnet *oif)
{
static u_int64_t counter;
struct tcphdr *const tcp = (struct tcphdr *) ((u_long *) ip+ ip->ip_hl);
struct udphdr *const udp = (struct udphdr *) ((u_long *) ip+ ip->ip_hl);
struct icmp *const icmp = (struct icmp *) ((u_long *) ip + ip->ip_hl);
int count;
count = f ? f->fw_pcnt : ++counter;
if (fw_verbose_limit != 0 && count > fw_verbose_limit)
return;
/* Print command name */
printf("ipfw: %d ", f ? f->fw_number : -1);
if (!f)
printf("Refuse");
else
switch (f->fw_flg & IP_FW_F_COMMAND) {
case IP_FW_F_DENY:
printf("Deny");
break;
case IP_FW_F_REJECT:
if (f->fw_reject_code == IP_FW_REJECT_RST)
printf("Reset");
else
printf("Unreach");
break;
case IP_FW_F_ACCEPT:
printf("Accept");
break;
case IP_FW_F_COUNT:
printf("Count");
break;
case IP_FW_F_DIVERT:
printf("Divert %d", f->fw_divert_port);
break;
case IP_FW_F_TEE:
printf("Tee %d", f->fw_divert_port);
break;
case IP_FW_F_SKIPTO:
printf("SkipTo %d", f->fw_skipto_rule);
break;
default:
printf("UNKNOWN");
break;
}
printf(" ");
switch (ip->ip_p) {
case IPPROTO_TCP:
printf("TCP ");
print_ip(ip->ip_src);
if ((ip->ip_off & IP_OFFMASK) == 0)
printf(":%d ", ntohs(tcp->th_sport));
else
printf(" ");
print_ip(ip->ip_dst);
if ((ip->ip_off & IP_OFFMASK) == 0)
printf(":%d", ntohs(tcp->th_dport));
break;
case IPPROTO_UDP:
printf("UDP ");
print_ip(ip->ip_src);
if ((ip->ip_off & IP_OFFMASK) == 0)
printf(":%d ", ntohs(udp->uh_sport));
else
printf(" ");
print_ip(ip->ip_dst);
if ((ip->ip_off & IP_OFFMASK) == 0)
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 (oif)
printf(" out via %s%d", oif->if_name, oif->if_unit);
else if (rif)
printf(" in via %s%d", rif->if_name, rif->if_unit);
if ((ip->ip_off & IP_OFFMASK))
printf(" Fragment = %d",ip->ip_off & IP_OFFMASK);
printf("\n");
if (fw_verbose_limit != 0 && count == fw_verbose_limit)
printf("ipfw: limit reached on rule #%d\n",
f ? f->fw_number : -1);
}
/*
* Parameters:
*
* ip Pointer to packet header (struct ip *)
* hlen Packet header length
* oif Outgoing interface, or NULL if packet is incoming
* ignport Ignore all divert/tee rules to this port (if non-zero)
* *m The packet; we set to NULL when/if we nuke it.
*
* Return value:
*
* 0 The packet is to be accepted and routed normally OR
* the packet was denied/rejected and has been dropped;
* in the latter case, *m is equal to NULL upon return.
* port Divert the packet to port.
*/
static int
ip_fw_chk(struct ip **pip, int hlen,
struct ifnet *oif, int ignport, struct mbuf **m)
{
struct ip_fw_chain *chain;
struct ip_fw *rule = NULL;
struct ip *ip = *pip;
struct ifnet *const rif = (*m)->m_pkthdr.rcvif;
u_short offset = (ip->ip_off & IP_OFFMASK);
u_short src_port, dst_port;
/*
* Go down the chain, looking for enlightment
*/
for (chain=LIST_FIRST(&ip_fw_chain); chain; chain = LIST_NEXT(chain, chain)) {
register struct ip_fw *const f = chain->rule;
/* Check direction inbound */
if (!oif && !(f->fw_flg & IP_FW_F_IN))
continue;
/* Check direction outbound */
if (oif && !(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 (((f->fw_flg & IP_FW_F_INVSRC) != 0) ^ ((ip->ip_src.s_addr
& f->fw_smsk.s_addr) != f->fw_src.s_addr))
continue;
/* If dest-addr doesn't match, not this rule. */
if (((f->fw_flg & IP_FW_F_INVDST) != 0) ^ ((ip->ip_dst.s_addr
& f->fw_dmsk.s_addr) != f->fw_dst.s_addr))
continue;
/* Interface check */
if ((f->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) {
struct ifnet *const iface = oif ? oif : rif;
/* Backwards compatibility hack for "via" */
if (!iface || !iface_match(iface,
&f->fw_in_if, f->fw_flg & IP_FW_F_OIFNAME))
continue;
} else {
/* Check receive interface */
if ((f->fw_flg & IP_FW_F_IIFACE)
&& (!rif || !iface_match(rif,
&f->fw_in_if, f->fw_flg & IP_FW_F_IIFNAME)))
continue;
/* Check outgoing interface */
if ((f->fw_flg & IP_FW_F_OIFACE)
&& (!oif || !iface_match(oif,
&f->fw_out_if, f->fw_flg & IP_FW_F_OIFNAME)))
continue;
}
/* Check IP options */
if (f->fw_ipopt != f->fw_ipnopt && !ipopts_match(ip, f))
continue;
/* Check protocol; if wildcard, match */
if (f->fw_prot == IPPROTO_IP)
goto got_match;
/* If different, don't match */
if (ip->ip_p != f->fw_prot)
continue;
#define PULLUP_TO(len) do { \
if ((*m)->m_len < (len) \
&& (*m = m_pullup(*m, (len))) == 0) { \
goto bogusfrag; \
} \
*pip = ip = mtod(*m, struct ip *); \
offset = (ip->ip_off & IP_OFFMASK); \
} while (0)
/* Protocol specific checks */
switch (ip->ip_p) {
case IPPROTO_TCP:
{
struct tcphdr *tcp;
if (offset == 1) /* cf. RFC 1858 */
goto bogusfrag;
if (offset != 0) {
/*
* TCP flags and ports aren't available in this
* packet -- if this rule specified either one,
* we consider the rule a non-match.
*/
if (f->fw_nports != 0 ||
f->fw_tcpf != f->fw_tcpnf)
continue;
break;
}
PULLUP_TO(hlen + 14);
tcp = (struct tcphdr *) ((u_long *)ip + ip->ip_hl);
if (f->fw_tcpf != f->fw_tcpnf && !tcpflg_match(tcp, f))
continue;
src_port = ntohs(tcp->th_sport);
dst_port = ntohs(tcp->th_dport);
goto check_ports;
}
case IPPROTO_UDP:
{
struct udphdr *udp;
if (offset != 0) {
/*
* Port specification is unavailable -- if this
* rule specifies a port, we consider the rule
* a non-match.
*/
if (f->fw_nports != 0)
continue;
break;
}
PULLUP_TO(hlen + 4);
udp = (struct udphdr *) ((u_long *)ip + ip->ip_hl);
src_port = ntohs(udp->uh_sport);
dst_port = ntohs(udp->uh_dport);
check_ports:
if (!port_match(&f->fw_uar.fw_pts[0],
IP_FW_GETNSRCP(f), src_port,
f->fw_flg & IP_FW_F_SRNG))
continue;
if (!port_match(&f->fw_uar.fw_pts[IP_FW_GETNSRCP(f)],
IP_FW_GETNDSTP(f), dst_port,
f->fw_flg & IP_FW_F_DRNG))
continue;
break;
}
case IPPROTO_ICMP:
{
struct icmp *icmp;
if (offset != 0) /* Type isn't valid */
break;
PULLUP_TO(hlen + 2);
icmp = (struct icmp *) ((u_long *)ip + ip->ip_hl);
if (!icmptype_match(icmp, f))
continue;
break;
}
#undef PULLUP_TO
bogusfrag:
if (fw_verbose)
ipfw_report(NULL, ip, rif, oif);
goto dropit;
}
got_match:
/* Ignore divert/tee rule if socket port is "ignport" */
switch (f->fw_flg & IP_FW_F_COMMAND) {
case IP_FW_F_DIVERT:
case IP_FW_F_TEE:
if (f->fw_divert_port == ignport)
continue; /* ignore this rule */
break;
}
/* Update statistics */
f->fw_pcnt += 1;
f->fw_bcnt += ip->ip_len;
f->timestamp = time.tv_sec;
/* Log to console if desired */
if ((f->fw_flg & IP_FW_F_PRN) && fw_verbose)
ipfw_report(f, ip, rif, oif);
/* Take appropriate action */
switch (f->fw_flg & IP_FW_F_COMMAND) {
case IP_FW_F_ACCEPT:
return(0);
case IP_FW_F_COUNT:
continue;
case IP_FW_F_DIVERT:
return(f->fw_divert_port);
case IP_FW_F_TEE:
/*
* XXX someday tee packet here, but beware that you
* can't use m_copym() or m_copypacket() because
* the divert input routine modifies the mbuf
* (and these routines only increment reference
* counts in the case of mbuf clusters), so need
* to write custom routine.
*/
continue;
case IP_FW_F_SKIPTO:
#ifdef DIAGNOSTIC
while (LIST_NEXT(chain, chain)
&& LIST_NEXT(chain, chain)->rule->fw_number
< f->fw_skipto_rule)
#else
while (LIST_NEXT(chain, chain)->rule->fw_number
< f->fw_skipto_rule)
#endif
chain = LIST_NEXT(chain, chain);
continue;
}
/* Deny/reject this packet using this rule */
rule = f;
break;
}
#ifdef DIAGNOSTIC
/* Rule 65535 should always be there and should always match */
if (!chain)
panic("ip_fw: chain");
#endif
/*
* At this point, we're going to drop the packet.
* Send a reject notice if all of the following are true:
*
* - The packet matched a reject rule
* - The packet is not an ICMP packet, or is an ICMP query packet
* - The packet is not a multicast or broadcast packet
*/
if ((rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_REJECT
&& (ip->ip_p != IPPROTO_ICMP || is_icmp_query(ip))
&& !((*m)->m_flags & (M_BCAST|M_MCAST))
&& !IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
switch (rule->fw_reject_code) {
case IP_FW_REJECT_RST:
{
struct tcphdr *const tcp =
(struct tcphdr *) ((u_long *)ip + ip->ip_hl);
struct tcpiphdr ti, *const tip = (struct tcpiphdr *) ip;
if (offset != 0 || (tcp->th_flags & TH_RST))
break;
ti.ti_i = *((struct ipovly *) ip);
ti.ti_t = *tcp;
bcopy(&ti, ip, sizeof(ti));
NTOHL(tip->ti_seq);
NTOHL(tip->ti_ack);
tip->ti_len = ip->ip_len - hlen - (tip->ti_off << 2);
if (tcp->th_flags & TH_ACK) {
tcp_respond(NULL, tip, *m,
(tcp_seq)0, ntohl(tcp->th_ack), TH_RST);
} else {
if (tcp->th_flags & TH_SYN)
tip->ti_len++;
tcp_respond(NULL, tip, *m, tip->ti_seq
+ tip->ti_len, (tcp_seq)0, TH_RST|TH_ACK);
}
*m = NULL;
break;
}
default: /* Send an ICMP unreachable using code */
icmp_error(*m, ICMP_UNREACH,
rule->fw_reject_code, 0L, 0);
*m = NULL;
break;
}
}
dropit:
/*
* Finally, drop the packet.
*/
if (*m) {
m_freem(*m);
*m = NULL;
}
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(("%s malloc said no\n", err_prefix));
if (fwc) free(fwc, M_IPFW);
if (ftmp) free(ftmp, M_IPFW);
return (ENOSPC);
}
bcopy(frwl, ftmp, sizeof(struct ip_fw));
ftmp->fw_in_if.fu_via_if.name[FW_IFNLEN - 1] = '\0';
ftmp->fw_pcnt = 0L;
ftmp->fw_bcnt = 0L;
fwc->rule = ftmp;
s = splnet();
if (!LIST_FIRST(chainptr)) {
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);
dprintf(("%s bad rule number\n", err_prefix));
return (EINVAL);
}
/* If entry number is 0, find highest numbered rule and add 100 */
if (ftmp->fw_number == 0) {
for (fcp = LIST_FIRST(chainptr); fcp; fcp = LIST_NEXT(fcp, chain)) {
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 = LIST_FIRST(chainptr); fcp; fcp = LIST_NEXT(fcp, chain)) {
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, u_short number)
{
struct ip_fw_chain *fcp;
fcp = LIST_FIRST(chainptr);
if (number != (u_short)-1) {
for (; fcp; fcp = LIST_NEXT(fcp, chain)) {
if (fcp->rule->fw_number == number) {
int s;
/* prevent access to rules while removing them */
s = splnet();
while (fcp && fcp->rule->fw_number == number) {
struct ip_fw_chain *next;
next = LIST_NEXT(fcp, chain);
LIST_REMOVE(fcp, chain);
free(fcp->rule, M_IPFW);
free(fcp, M_IPFW);
fcp = next;
}
splx(s);
return 0;
}
}
}
return (EINVAL);
}
static int
zero_entry(struct mbuf *m)
{
struct ip_fw *frwl;
struct ip_fw_chain *fcp;
int s;
if (m) {
if (m->m_len != sizeof(struct ip_fw))
return(EINVAL);
frwl = mtod(m, struct ip_fw *);
}
else
frwl = NULL;
if (!frwl) {
s = splnet();
for (fcp = LIST_FIRST(&ip_fw_chain); fcp; fcp = LIST_NEXT(fcp, chain)) {
fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0;
fcp->rule->timestamp = 0;
}
splx(s);
}
else {
int cleared = 0;
/*
* 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.
*/
for (fcp = LIST_FIRST(&ip_fw_chain); fcp; fcp = LIST_NEXT(fcp, chain))
if (frwl->fw_number == fcp->rule->fw_number) {
s = splnet();
while (fcp && frwl->fw_number == fcp->rule->fw_number) {
fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0;
fcp->rule->timestamp = 0;
fcp = LIST_NEXT(fcp, chain);
}
splx(s);
cleared = 1;
break;
}
if (!cleared)
return(EINVAL); /* we didn't find any matching rules */
}
if (fw_verbose) {
if (frwl)
printf("ipfw: Entry %d cleared.\n", frwl->fw_number);
else
printf("ipfw: Accounting cleared.\n");
}
return(0);
}
static struct ip_fw *
check_ipfw_mbuf(struct mbuf *m)
{
/* Check length */
if (m->m_len != sizeof(struct ip_fw)) {
dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len,
sizeof(struct ip_fw)));
return (NULL);
}
return(check_ipfw_struct(mtod(m, struct ip_fw *)));
}
static struct ip_fw *
check_ipfw_struct(struct ip_fw *frwl)
{
/* Check for invalid flag bits */
if ((frwl->fw_flg & ~IP_FW_F_MASK) != 0) {
dprintf(("%s undefined flag bits set (flags=%x)\n",
err_prefix, frwl->fw_flg));
return (NULL);
}
/* Must apply to incoming or outgoing (or both) */
if (!(frwl->fw_flg & (IP_FW_F_IN | IP_FW_F_OUT))) {
dprintf(("%s neither in nor out\n", err_prefix));
return (NULL);
}
/* Empty interface name is no good */
if (((frwl->fw_flg & IP_FW_F_IIFNAME)
&& !*frwl->fw_in_if.fu_via_if.name)
|| ((frwl->fw_flg & IP_FW_F_OIFNAME)
&& !*frwl->fw_out_if.fu_via_if.name)) {
dprintf(("%s empty interface name\n", err_prefix));
return (NULL);
}
/* Sanity check interface matching */
if ((frwl->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) {
; /* allow "via" backwards compatibility */
} else if ((frwl->fw_flg & IP_FW_F_IN)
&& (frwl->fw_flg & IP_FW_F_OIFACE)) {
dprintf(("%s outgoing interface check on incoming\n",
err_prefix));
return (NULL);
}
/* Sanity check port ranges */
if ((frwl->fw_flg & IP_FW_F_SRNG) && IP_FW_GETNSRCP(frwl) < 2) {
dprintf(("%s src range set but n_src_p=%d\n",
err_prefix, IP_FW_GETNSRCP(frwl)));
return (NULL);
}
if ((frwl->fw_flg & IP_FW_F_DRNG) && IP_FW_GETNDSTP(frwl) < 2) {
dprintf(("%s dst range set but n_dst_p=%d\n",
err_prefix, IP_FW_GETNDSTP(frwl)));
return (NULL);
}
if (IP_FW_GETNSRCP(frwl) + IP_FW_GETNDSTP(frwl) > IP_FW_MAX_PORTS) {
dprintf(("%s too many ports (%d+%d)\n",
err_prefix, IP_FW_GETNSRCP(frwl), IP_FW_GETNDSTP(frwl)));
return (NULL);
}
/*
* Protocols other than TCP/UDP don't use port range
*/
if ((frwl->fw_prot != IPPROTO_TCP) &&
(frwl->fw_prot != IPPROTO_UDP) &&
(IP_FW_GETNSRCP(frwl) || IP_FW_GETNDSTP(frwl))) {
dprintf(("%s port(s) specified for non TCP/UDP rule\n",
err_prefix));
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(("%s rule never matches\n", err_prefix));
return(NULL);
}
if ((frwl->fw_flg & IP_FW_F_FRAG) &&
(frwl->fw_prot == IPPROTO_UDP || frwl->fw_prot == IPPROTO_TCP)) {
if (frwl->fw_nports) {
dprintf(("%s cannot mix 'frag' and ports\n", err_prefix));
return(NULL);
}
if (frwl->fw_prot == IPPROTO_TCP &&
frwl->fw_tcpf != frwl->fw_tcpnf) {
dprintf(("%s cannot mix 'frag' and TCP flags\n", err_prefix));
return(NULL);
}
}
/* Check command specific stuff */
switch (frwl->fw_flg & IP_FW_F_COMMAND)
{
case IP_FW_F_REJECT:
if (frwl->fw_reject_code >= 0x100
&& !(frwl->fw_prot == IPPROTO_TCP
&& frwl->fw_reject_code == IP_FW_REJECT_RST)) {
dprintf(("%s unknown reject code\n", err_prefix));
return(NULL);
}
break;
case IP_FW_F_DIVERT: /* Diverting to port zero is invalid */
case IP_FW_F_TEE:
if (frwl->fw_divert_port == 0) {
dprintf(("%s can't divert to port 0\n", err_prefix));
return (NULL);
}
break;
case IP_FW_F_DENY:
case IP_FW_F_ACCEPT:
case IP_FW_F_COUNT:
case IP_FW_F_SKIPTO:
break;
default:
dprintf(("%s invalid command\n", err_prefix));
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 = LIST_FIRST(&ip_fw_chain);
*mm = m = m_get(M_WAIT, MT_SOOPTS);
for (; fcp; fcp = LIST_NEXT(fcp, chain)) {
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 (LIST_FIRST(&ip_fw_chain) != NULL &&
LIST_FIRST(&ip_fw_chain)->rule->fw_number != (u_short)-1) {
struct ip_fw_chain *fcp = LIST_FIRST(&ip_fw_chain);
int s = splnet();
LIST_REMOVE(LIST_FIRST(&ip_fw_chain), 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("%s NULL mbuf ptr\n", err_prefix);
return (EINVAL);
}
if (stage == IP_FW_ADD) {
struct ip_fw *frwl = check_ipfw_mbuf(m);
if (!frwl)
error = EINVAL;
else
error = add_entry(&ip_fw_chain, frwl);
if (m) (void)m_free(m);
return error;
}
if (stage == IP_FW_DEL) {
if (m->m_len != sizeof(struct ip_fw)) {
dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len,
sizeof(struct ip_fw)));
error = EINVAL;
} else if (mtod(m, struct ip_fw *)->fw_number == (u_short)-1) {
dprintf(("%s can't delete rule 65535\n", err_prefix));
error = EINVAL;
} else
error = del_entry(&ip_fw_chain,
mtod(m, struct ip_fw *)->fw_number);
if (m) (void)m_free(m);
return error;
}
dprintf(("%s unknown request %d\n", err_prefix, stage));
if (m) (void)m_free(m);
return (EINVAL);
}
void
ip_fw_init(void)
{
struct ip_fw default_rule;
ip_fw_chk_ptr = ip_fw_chk;
ip_fw_ctl_ptr = ip_fw_ctl;
LIST_INIT(&ip_fw_chain);
bzero(&default_rule, sizeof default_rule);
default_rule.fw_prot = IPPROTO_IP;
default_rule.fw_number = (u_short)-1;
#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
default_rule.fw_flg |= IP_FW_F_ACCEPT;
#else
default_rule.fw_flg |= IP_FW_F_DENY;
#endif
default_rule.fw_flg |= IP_FW_F_IN | IP_FW_F_OUT;
if (check_ipfw_struct(&default_rule) == NULL ||
add_entry(&ip_fw_chain, &default_rule))
panic(__FUNCTION__);
printf("IP packet filtering initialized, "
#ifdef IPDIVERT
"divert enabled, ");
#else
"divert disabled, ");
#endif
#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
printf("default to accept, ");
#endif
#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 (LIST_FIRST(&ip_fw_chain) != NULL) {
struct ip_fw_chain *fcp = LIST_FIRST(&ip_fw_chain);
LIST_REMOVE(LIST_FIRST(&ip_fw_chain), 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)
{
MOD_DISPATCH(ipfw, lkmtp, cmd, ver,
ipfw_load, ipfw_unload, lkm_nullcmd);
}
#endif
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