630 lines
14 KiB
C
630 lines
14 KiB
C
/*
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* Copyright (c) 1993 Daniel Boulet
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* Copyright (c) 1994 Ugen J.S.Antsilevich
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*
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* Redistribution and use in source forms, with and without modification,
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* are permitted provided that this entire comment appears intact.
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*
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* Redistribution in binary form may occur without any restrictions.
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* Obviously, it would be nice if you gave credit where credit is due
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* but requiring it would be too onerous.
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*
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* This software is provided ``AS IS'' without any warranties of any kind.
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*
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* $Id: ip_fw.c,v 1.30 1996/02/23 20:11:37 phk Exp $
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*/
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/*
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* Implement IP packet firewall
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/queue.h>
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#if 0 /* XXX -current, but not -stable */
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#endif
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#include <net/if.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/tcp.h>
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#include <netinet/udp.h>
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#include <netinet/ip_icmp.h>
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#include <netinet/ip_fw.h>
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static int fw_debug = 1;
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#ifdef IPFIREWALL_VERBOSE
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static int fw_verbose = 1;
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#else
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static int fw_verbose = 0;
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#endif
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u_short ip_fw_policy = IP_FW_P_DENY;
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LIST_HEAD (ip_fw_head, ip_fw_chain) ip_fw_chain;
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#ifdef SYSCTL_NODE
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SYSCTL_NODE(net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
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SYSCTL_INT(net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, &fw_debug, 0, "");
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SYSCTL_INT(net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, &fw_verbose, 0, "");
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#endif
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#define dprintf(a) if (!fw_debug); else printf a
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#define print_ip(a) printf("%ld.%ld.%ld.%ld",(ntohl(a.s_addr)>>24)&0xFF,\
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(ntohl(a.s_addr)>>16)&0xFF,\
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(ntohl(a.s_addr)>>8)&0xFF,\
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(ntohl(a.s_addr))&0xFF);
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#define dprint_ip(a) if (!fw_debug); else print_ip(a)
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static int add_entry __P((struct ip_fw_head *chainptr, struct ip_fw *frwl));
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static int del_entry __P((struct ip_fw_head *chainptr, struct ip_fw *frwl));
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static struct ip_fw *
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check_ipfw_struct __P(( struct mbuf *m));
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static int ipopts_match __P((struct ip *ip, struct ip_fw *f));
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static int port_match __P((u_short *portptr, int nports, u_short port,
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int range_flag));
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static int tcpflg_match __P((struct tcphdr *tcp, struct ip_fw *f));
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static void ipfw_report __P((char *txt, int rule, struct ip *ip));
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/*
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* Returns 1 if the port is matched by the vector, 0 otherwise
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*/
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static inline int
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port_match(portptr, nports, port, range_flag)
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u_short *portptr;
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int nports;
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u_short port;
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int range_flag;
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{
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if (!nports)
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return 1;
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if (range_flag) {
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if (portptr[0] <= port && port <= portptr[1]) {
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return 1;
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}
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nports -= 2;
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portptr += 2;
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}
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while (nports-- > 0) {
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if (*portptr++ == port) {
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return 1;
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}
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}
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return 0;
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}
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static int
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tcpflg_match(tcp, f)
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struct tcphdr *tcp;
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struct ip_fw *f;
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{
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u_char flg_set, flg_clr;
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flg_set = tcp->th_flags & f->fw_tcpf;
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flg_clr = tcp->th_flags & f->fw_tcpnf;
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if (flg_set != f->fw_tcpf)
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return 0;
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if (flg_clr)
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return 0;
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return 1;
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}
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static int
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ipopts_match(ip, f)
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struct ip *ip;
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struct ip_fw *f;
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{
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register u_char *cp;
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int opt, optlen, cnt;
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u_char opts, nopts, nopts_sve;
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cp = (u_char *)(ip + 1);
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cnt = (ip->ip_hl << 2) - sizeof (struct ip);
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opts = f->fw_ipopt;
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nopts = nopts_sve = f->fw_ipnopt;
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for (; cnt > 0; cnt -= optlen, cp += optlen) {
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opt = cp[IPOPT_OPTVAL];
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if (opt == IPOPT_EOL)
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break;
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if (opt == IPOPT_NOP)
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optlen = 1;
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else {
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optlen = cp[IPOPT_OLEN];
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if (optlen <= 0 || optlen > cnt) {
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goto bad;
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}
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}
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switch (opt) {
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default:
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break;
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case IPOPT_LSRR:
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opts &= ~IP_FW_IPOPT_LSRR;
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nopts &= ~IP_FW_IPOPT_LSRR;
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break;
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case IPOPT_SSRR:
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opts &= ~IP_FW_IPOPT_SSRR;
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nopts &= ~IP_FW_IPOPT_SSRR;
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break;
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case IPOPT_RR:
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opts &= ~IP_FW_IPOPT_RR;
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nopts &= ~IP_FW_IPOPT_RR;
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break;
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case IPOPT_TS:
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opts &= ~IP_FW_IPOPT_TS;
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nopts &= ~IP_FW_IPOPT_TS;
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break;
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}
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if (opts == nopts)
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break;
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}
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if (opts == 0 && nopts == nopts_sve)
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return 1;
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else
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return 0;
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bad:
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if (ip_fw_policy & IP_FW_P_MBIPO)
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return 1;
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else
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return 0;
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}
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static void
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ipfw_report(char *txt, int rule, struct ip *ip)
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{
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struct tcphdr *tcp = (struct tcphdr *) ((u_long *) ip + ip->ip_hl);
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struct udphdr *udp = (struct udphdr *) ((u_long *) ip + ip->ip_hl);
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struct icmp *icmp = (struct icmp *) ((u_long *) ip + ip->ip_hl);
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if (!fw_verbose)
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return;
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printf("ipfw: %d %s ",rule, txt);
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switch (ip->ip_p) {
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case IPPROTO_TCP:
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printf("TCP ");
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print_ip(ip->ip_src);
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printf(":%d ", ntohs(tcp->th_sport));
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print_ip(ip->ip_dst);
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printf(":%d", ntohs(tcp->th_dport));
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break;
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case IPPROTO_UDP:
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printf("UDP ");
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print_ip(ip->ip_src);
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printf(":%d ", ntohs(udp->uh_sport));
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print_ip(ip->ip_dst);
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printf(":%d", ntohs(udp->uh_dport));
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break;
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case IPPROTO_ICMP:
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printf("ICMP:%u ", icmp->icmp_type);
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print_ip(ip->ip_src);
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printf(" ");
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print_ip(ip->ip_dst);
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break;
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default:
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printf("P:%d ", ip->ip_p);
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print_ip(ip->ip_src);
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printf(" ");
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print_ip(ip->ip_dst);
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break;
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}
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if ((ip->ip_off & IP_OFFMASK))
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printf(" Fragment = %d",ip->ip_off & IP_OFFMASK);
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printf("\n");
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}
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/*
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* Returns 1 if it should be accepted, 0 otherwise.
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*/
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int
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ip_fw_chk(m, ip, rif, dir)
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struct mbuf *m;
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struct ip *ip;
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struct ifnet *rif;
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int dir;
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{
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struct ip_fw_chain *chain;
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register struct ip_fw *f = NULL;
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struct tcphdr *tcp = (struct tcphdr *) ((u_long *) ip + ip->ip_hl);
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struct udphdr *udp = (struct udphdr *) ((u_long *) ip + ip->ip_hl);
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struct icmp *icmp = (struct icmp *) ((u_long *) ip + ip->ip_hl);
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struct ifaddr *ia = NULL, *ia_p;
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struct in_addr src, dst, ia_i;
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u_short src_port = 0, dst_port = 0;
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u_short f_prt = 0, prt, len = 0;
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/*
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* ... else if non-zero, highly unusual and interesting, but
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* we're not going to pass it...
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*/
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if ((ip->ip_off & IP_OFFMASK) == 1) {
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ipfw_report("Refuse", -1, ip);
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m_freem(m);
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return 0;
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}
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src = ip->ip_src;
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dst = ip->ip_dst;
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/*
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* If we got interface from which packet came-store pointer to it's
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* first adress
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*/
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if (rif != NULL)
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ia = rif->if_addrlist;
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/*
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* Determine the protocol and extract some useful stuff
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*/
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switch (ip->ip_p) {
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case IPPROTO_TCP:
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src_port = ntohs(tcp->th_sport);
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dst_port = ntohs(tcp->th_dport);
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prt = IP_FW_F_TCP;
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len = sizeof (*tcp);
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break;
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case IPPROTO_UDP:
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src_port = ntohs(udp->uh_sport);
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dst_port = ntohs(udp->uh_dport);
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prt = IP_FW_F_UDP;
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len = sizeof (*udp);
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break;
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case IPPROTO_ICMP:
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prt = IP_FW_F_ICMP;
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len = sizeof (*icmp);
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break;
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default:
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prt = IP_FW_F_ALL;
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break;
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}
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/* XXX Check that we have sufficient header for TCP analysis */
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/*
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* Go down the chain, looking for enlightment
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*/
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for (chain=ip_fw_chain.lh_first; chain; chain = chain->chain.le_next) {
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f = chain->rule;
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/* Check direction inbound */
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if (!dir && !(f->fw_flg & IP_FW_F_IN))
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continue;
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/* Check direction outbound */
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if (dir && !(f->fw_flg & IP_FW_F_OUT))
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continue;
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/* Fragments */
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if ((f->fw_flg & IP_FW_F_FRAG) && !(ip->ip_off & IP_OFFMASK))
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continue;
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/* If src-addr doesn't match, not this rule. */
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if ((src.s_addr & f->fw_smsk.s_addr) != f->fw_src.s_addr)
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continue;
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/* If dest-addr doesn't match, not this rule. */
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if ((dst.s_addr & f->fw_dmsk.s_addr) != f->fw_dst.s_addr)
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continue;
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/* If a i/f name was specified, and we don't know */
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if ((f->fw_flg & IP_FW_F_IFNAME) && !rif)
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continue;
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/* If a i/f name was specified, check it */
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if ((f->fw_flg & IP_FW_F_IFNAME) && f->fw_via_name[0]) {
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/* Not same unit, don't match */
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if (rif->if_unit != f->fw_via_unit)
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continue;
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/* Not same name */
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if (strncmp(rif->if_name, f->fw_via_name, FW_IFNLEN))
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continue;
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}
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/* If a i/f addr was specified, check it */
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if ((f->fw_flg & IP_FW_F_IFNAME) && f->fw_via_ip.s_addr) {
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int match = 0;
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for (ia_p = ia; ia_p != NULL; ia_p = ia_p->ifa_next) {
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if ((ia_p->ifa_addr == NULL))
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continue;
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if (ia_p->ifa_addr->sa_family != AF_INET)
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continue;
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ia_i.s_addr =
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((struct sockaddr_in *)
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(ia_p->ifa_addr))->sin_addr.s_addr;
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if (ia_i.s_addr != f->fw_via_ip.s_addr)
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continue;
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match = 1;
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break;
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}
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if (!match)
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continue;
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}
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/*
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* Check IP options
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*/
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if (f->fw_ipopt != f->fw_ipnopt)
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if (!ipopts_match(ip, f))
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continue;
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/*
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* Check protocol
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*/
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f_prt = f->fw_flg & IP_FW_F_KIND;
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/* If wildcard, match */
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if (f_prt == IP_FW_F_ALL)
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goto got_match;
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/* If different, dont match */
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if (prt != f_prt)
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continue;
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/* ICMP, done */
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if (prt == IP_FW_F_ICMP)
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goto got_match;
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/* Fragments can't match past this point */
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if (ip->ip_off & IP_OFFMASK)
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continue;
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/* TCP, a little more checking */
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if (prt == IP_FW_F_TCP &&
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(f->fw_tcpf != f->fw_tcpnf) &&
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(!tcpflg_match(tcp, f)))
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continue;
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if (!port_match(&f->fw_pts[0], f->fw_nsp,
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src_port, f->fw_flg & IP_FW_F_SRNG))
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continue;
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if (!port_match(&f->fw_pts[f->fw_nsp], f->fw_ndp,
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dst_port, f->fw_flg & IP_FW_F_DRNG))
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continue;
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got_match:
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f->fw_pcnt++;
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f->fw_bcnt+=ip->ip_len;
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if (f->fw_flg & IP_FW_F_PRN) {
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if (f->fw_flg & IP_FW_F_ACCEPT)
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ipfw_report("Accept", f->fw_number, ip);
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else if (f->fw_flg & IP_FW_F_COUNT)
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ipfw_report("Count", f->fw_number, ip);
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else
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ipfw_report("Deny", f->fw_number, ip);
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}
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if (f->fw_flg & IP_FW_F_ACCEPT)
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return 1;
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if (f->fw_flg & IP_FW_F_COUNT)
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continue;
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break;
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}
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/*
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* Don't icmp outgoing packets at all
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*/
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if (f != NULL && !dir) {
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/*
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* Do not ICMP reply to icmp packets....:) or to packets
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* rejected by entry without the special ICMP reply flag.
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*/
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if ((f_prt != IP_FW_F_ICMP) && (f->fw_flg & IP_FW_F_ICMPRPL)) {
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if (f_prt == IP_FW_F_ALL)
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icmp_error(m, ICMP_UNREACH,
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ICMP_UNREACH_HOST, 0L, 0);
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else
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icmp_error(m, ICMP_UNREACH,
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ICMP_UNREACH_PORT, 0L, 0);
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return 0;
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}
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}
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m_freem(m);
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return 0;
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}
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static int
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add_entry(chainptr, frwl)
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struct ip_fw_head *chainptr;
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struct ip_fw *frwl;
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{
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struct ip_fw *ftmp = 0;
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struct ip_fw_chain *fwc = 0, *fcp, *fcpl = 0;
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u_short nbr = 0;
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int s;
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s = splnet();
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fwc = malloc(sizeof *fwc, M_IPFW, M_DONTWAIT);
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ftmp = malloc(sizeof *ftmp, M_IPFW, M_DONTWAIT);
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if (!fwc || !ftmp) {
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dprintf(("ip_fw_ctl: malloc said no\n"));
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if (fwc) free(fwc, M_IPFW);
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if (ftmp) free(ftmp, M_IPFW);
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splx(s);
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return (ENOSPC);
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}
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bcopy(frwl, ftmp, sizeof(struct ip_fw));
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ftmp->fw_pcnt = 0L;
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ftmp->fw_bcnt = 0L;
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fwc->rule = ftmp;
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if (!chainptr->lh_first) {
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LIST_INSERT_HEAD(chainptr, fwc, chain);
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} else if (ftmp->fw_number == (u_short)-1) {
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if (fwc) free(fwc, M_IPFW);
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if (ftmp) free(ftmp, M_IPFW);
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splx(s);
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return (EINVAL);
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} else {
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nbr=0;
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for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next)
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if (fcp->rule->fw_number == (u_short)-1 ||
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( ftmp->fw_number &&
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fcp->rule->fw_number > ftmp->fw_number)) {
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if (!ftmp->fw_number)
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ftmp->fw_number = nbr + 100;
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if (fcpl) {
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LIST_INSERT_AFTER(fcpl, fwc, chain);
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} else {
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LIST_INSERT_HEAD(chainptr, fwc, chain);
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}
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break;
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} else {
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nbr=fcp->rule->fw_number;
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fcpl = fcp;
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}
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}
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splx(s);
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return (0);
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}
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static int
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del_entry(chainptr, frwl)
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struct ip_fw_head *chainptr;
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struct ip_fw *frwl;
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{
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struct ip_fw_chain *fcp;
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int s;
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s = splnet();
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fcp = chainptr->lh_first;
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if (fcp->rule->fw_number == (u_short)-1)
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return (EINVAL);
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for (; fcp; fcp = fcp->chain.le_next) {
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if (fcp->rule->fw_number == frwl->fw_number) {
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LIST_REMOVE(fcp, chain);
|
|
splx(s);
|
|
free(fcp->rule, M_IPFW);
|
|
free(fcp, M_IPFW);
|
|
return 0;
|
|
}
|
|
}
|
|
splx(s);
|
|
return (EINVAL);
|
|
}
|
|
|
|
static struct ip_fw *
|
|
check_ipfw_struct(m)
|
|
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);
|
|
}
|
|
#if 0
|
|
if ((frwl->fw_flg & IP_FW_F_KIND) == IP_FW_F_ICMP) {
|
|
dprintf(("ip_fw_ctl: request for unsupported ICMP frwling\n"));
|
|
return (NULL);
|
|
}
|
|
#endif
|
|
return frwl;
|
|
}
|
|
|
|
int
|
|
ip_fw_ctl(stage, m)
|
|
int stage;
|
|
struct mbuf *m;
|
|
{
|
|
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;
|
|
LIST_REMOVE(ip_fw_chain.lh_first, chain);
|
|
free(fcp->rule, M_IPFW);
|
|
free(fcp, M_IPFW);
|
|
}
|
|
return (0);
|
|
}
|
|
if (stage == IP_FW_ZERO) {
|
|
struct ip_fw_chain *fcp;
|
|
for (fcp = ip_fw_chain.lh_first; fcp; fcp = fcp->chain.le_next)
|
|
fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0;
|
|
return (0);
|
|
}
|
|
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)
|
|
return (EINVAL);
|
|
|
|
if (stage == IP_FW_ADD)
|
|
return (add_entry(&ip_fw_chain, frwl));
|
|
else
|
|
return (del_entry(&ip_fw_chain, frwl));
|
|
}
|
|
dprintf(("ip_fw_ctl: unknown request %d\n", stage));
|
|
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\n");
|
|
}
|