/* * 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. * * $Id$ */ /* * Implement IP packet firewall */ #ifndef IPFIREWALL_MODULE #include "opt_ipfw.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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; /* * ccj - No current need for firewall so have provided the MIB. */ #if 0 #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 #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_DIM * sizeof(unsigned) * 8 && (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 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_addrlist; ia; ia = ia->ifa_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 int 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=ip_fw_chain.lh_first; chain; chain = chain->chain.le_next) { 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_pts[0], IP_FW_GETNSRCP(f), src_port, f->fw_flg & IP_FW_F_SRNG)) continue; if (!port_match(&f->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 = rtems_bsdnet_seconds_since_boot(); /* 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 (chain->chain.le_next && chain->chain.le_next->rule->fw_number < f->fw_skipto_rule) #else while (chain->chain.le_next->rule->fw_number < f->fw_skipto_rule) #endif chain = chain->chain.le_next; 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 * - 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 && !((*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 (!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); 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 = 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, u_short number) { struct ip_fw_chain *fcp; int s; s = splnet(); fcp = chainptr->lh_first; if (number != (u_short)-1) { for (; fcp; fcp = fcp->chain.le_next) { if (fcp->rule->fw_number == 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) { if (m->m_len != sizeof(struct ip_fw)) return(EINVAL); frwl = mtod(m, struct ip_fw *); } 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); 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, (int)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' with 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 = 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("%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, (int)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 #include #include 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