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freebsd-dev/sys/netinet/ip_fw.c
Julian Elischer bb60f459a0 Add optional code to change the way that divert and ipfw work together. 
Prior to this change, Accidental recursion protection was done by
the diverted daemon feeding back the divert port number it got
the packet on, as the port number on a sendto(). IPFW knew not to
redivert a packet to this port (again). Processing of the ruleset
started at the beginning again, skipping that divert port.

The new semantic (which is how we should have done it the first time)
is that the port number in the sendto() is the rule number AFTER which
processing should restart, and on a recvfrom(), the port number is the
rule number which caused the diversion. This is much more flexible,
and also more intuitive. If the user uses the same sockaddr received
when resending, processing resumes at the rule number following that
that caused the diversion. The user can however select to resume rule
processing at any rule. (0 is restart at the beginning)

To enable the new code use

option	IPFW_DIVERT_RESTART

This should become the default as soon as people have looked at it a bit
1998-05-25 10:37:48 +00:00

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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 1.83 1998/05/19 14:04:29 dg 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 <net/route.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 __inline int
iface_match __P((struct ifnet *ifp, union ip_fw_if *ifu,
int byname));
static int ipopts_match __P((struct ip *ip, struct ip_fw *f));
static __inline 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
#ifndef IPFW_DIVERT_RESTART
static int ip_fw_chk __P((struct ip **pip, int hlen,
struct ifnet *oif, int ignport, struct mbuf **m));
#else
static int ip_fw_chk __P((struct ip **pip, int hlen,
struct ifnet *oif, int pastrule, struct mbuf **m));
#endif /* IPFW_DIVERT_RESTART */
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
* #ifndef IPFW_DIVERT_RESTART
* ignport Ignore all divert/tee rules to this port (if non-zero)
* #else
* pastrule Skip up to the first rule past this rule number;
* #endif
* *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
#ifndef IPFW_DIVERT_RESTART
ip_fw_chk(struct ip **pip, int hlen,
struct ifnet *oif, int ignport, struct mbuf **m)
#else
ip_fw_chk(struct ip **pip, int hlen,
struct ifnet *oif, int pastrule, struct mbuf **m)
#endif /* IPFW_DIVERT_RESTART */
{
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
* #ifdef IPFW_DIVERT_RESTART
* If we've been asked to start at a given rule immediatly, do so.
* #endif
*/
#ifndef IPFW_DIVERT_RESTART
for (chain=LIST_FIRST(&ip_fw_chain); chain; chain = LIST_NEXT(chain, chain)) {
#else
chain=LIST_FIRST(&ip_fw_chain);
if ( pastrule ) {
if (pastrule >= 65535)
goto dropit;
while (chain && (chain->rule->fw_number <= pastrule)) {
chain = LIST_NEXT(chain, chain);
}
if (! chain) goto dropit;
}
for (; chain; chain = LIST_NEXT(chain, chain)) {
#endif /* IPFW_DIVERT_RESTART */
register struct ip_fw *const f = chain->rule;
if (oif) {
/* Check direction outbound */
if (!(f->fw_flg & IP_FW_F_OUT))
continue;
} else {
/* Check direction inbound */
if (!(f->fw_flg & IP_FW_F_IN))
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:
#ifndef IPFW_DIVERT_RESTART
/* 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;
}
#endif /* IPFW_DIVERT_RESTART */
/* Update statistics */
f->fw_pcnt += 1;
f->fw_bcnt += ip->ip_len;
f->timestamp = time_second;
/* 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:
#ifdef IPFW_DIVERT_RESTART
ip_divert_in_cookie = f->fw_number;
#endif /* IPFW_DIVERT_RESTART */
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) {
/*
* If we have any number of rules, then it's worth while
* using clusters for this. The smaller case is rare.
* Note that using clusters for setsockopt is only in
* 3.0 at this time.
*/
struct ip_fw_chain *fcp = LIST_FIRST(&ip_fw_chain);
*mm = m = m_get(M_WAIT, MT_SOOPTS);
if (m == NULL)
return (ENOBUFS);
MCLGET(m, M_WAIT);
if(!(m->m_flags & M_EXT)) {
abort: m_freem(*mm);
*mm = NULL;
return (ENOBUFS);
}
m->m_len = 0;
for (; fcp; fcp = LIST_NEXT(fcp, chain)) {
/* Will we need a new cluster? */
if((m->m_len + sizeof *(fcp->rule)) > MCLBYTES) {
m = m->m_next = m_get(M_WAIT, MT_SOOPTS);
if (m == NULL) {
goto abort;
}
MCLGET(m, M_WAIT);
if (!(m->m_flags & M_EXT)) {
goto abort;
}
m->m_len = 0;
}
memcpy(m->m_data + m->m_len, fcp->rule,
sizeof *(fcp->rule));
m->m_len += sizeof *(fcp->rule);
}
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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