/* * 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. * * $FreeBSD$ */ /* * Implement IP packet firewall */ #if !defined(KLD_MODULE) #include "opt_ipfw.h" #include "opt_ipdn.h" #include "opt_ipdivert.h" #include "opt_inet.h" #ifndef INET #error IPFIREWALL requires INET. #endif /* INET */ #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DUMMYNET #include #endif #include #include #include #include #include #include #include /* XXX ethertype_ip */ static int fw_debug = 1; #ifdef IPFIREWALL_VERBOSE static int fw_verbose = 1; #else static int fw_verbose = 0; #endif static int fw_one_pass = 1 ; #ifdef IPFIREWALL_VERBOSE_LIMIT static int fw_verbose_limit = IPFIREWALL_VERBOSE_LIMIT; #else static int fw_verbose_limit = 0; #endif static u_int64_t counter; /* counter for ipfw_report(NULL...) */ #define IPFW_DEFAULT_RULE ((u_int)(u_short)~0) LIST_HEAD (ip_fw_head, ip_fw_chain) ip_fw_chain; MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); #ifdef SYSCTL_NODE SYSCTL_DECL(_net_inet_ip); 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, "Enable printing of debug ip_fw statements"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW, &fw_one_pass, 0, "Only do a single pass through ipfw rules when using divert(4)"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, &fw_verbose, 0, "Log matches to ipfw rules"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, &fw_verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); #endif #define dprintf(a) do { \ if (fw_debug) \ printf a; \ } while (0) #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 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 ip_fw *)); static int resetlog_entry __P((struct ip_fw *)); static int check_ipfw_struct __P((struct ip_fw *m)); 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)); static void flush_rule_ptrs(void); static int ip_fw_chk __P((struct ip **pip, int hlen, struct ifnet *oif, u_int16_t *cookie, struct mbuf **m, struct ip_fw_chain **flow_id, struct sockaddr_in **next_hop)); static int ip_fw_ctl __P((struct sockopt *sopt)); 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) * NBBY)] & (1U << (type % (sizeof(unsigned) * NBBY))))) 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_int32_t *)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) { if (ip) { struct tcphdr *const tcp = (struct tcphdr *) ((u_int32_t *) ip+ ip->ip_hl); struct udphdr *const udp = (struct udphdr *) ((u_int32_t *) ip+ ip->ip_hl); struct icmp *const icmp = (struct icmp *) ((u_int32_t *) ip + ip->ip_hl); u_int64_t count; char *action; char action2[32], proto[47], name[18], fragment[17]; int len; count = f ? f->fw_pcnt : ++counter; if ((f == NULL && fw_verbose_limit != 0 && count > fw_verbose_limit) || (f && f->fw_logamount != 0 && count > f->fw_loghighest)) return; /* Print command name */ snprintf(SNPARGS(name, 0), "ipfw: %d", f ? f->fw_number : -1); action = action2; if (!f) action = "Refuse"; else { switch (f->fw_flg & IP_FW_F_COMMAND) { case IP_FW_F_DENY: action = "Deny"; break; case IP_FW_F_REJECT: if (f->fw_reject_code == IP_FW_REJECT_RST) action = "Reset"; else action = "Unreach"; break; case IP_FW_F_ACCEPT: action = "Accept"; break; case IP_FW_F_COUNT: action = "Count"; break; #ifdef IPDIVERT case IP_FW_F_DIVERT: snprintf(SNPARGS(action2, 0), "Divert %d", f->fw_divert_port); break; case IP_FW_F_TEE: snprintf(SNPARGS(action2, 0), "Tee %d", f->fw_divert_port); break; #endif case IP_FW_F_SKIPTO: snprintf(SNPARGS(action2, 0), "SkipTo %d", f->fw_skipto_rule); break; #ifdef DUMMYNET case IP_FW_F_PIPE: snprintf(SNPARGS(action2, 0), "Pipe %d", f->fw_skipto_rule); break; #endif #ifdef IPFIREWALL_FORWARD case IP_FW_F_FWD: if (f->fw_fwd_ip.sin_port) snprintf(SNPARGS(action2, 0), "Forward to %s:%d", inet_ntoa(f->fw_fwd_ip.sin_addr), f->fw_fwd_ip.sin_port); else snprintf(SNPARGS(action2, 0), "Forward to %s", inet_ntoa(f->fw_fwd_ip.sin_addr)); break; #endif default: action = "UNKNOWN"; break; } } len = 0; switch (ip->ip_p) { case IPPROTO_TCP: len = snprintf(SNPARGS(proto, 0), "TCP %s", inet_ntoa(ip->ip_src)); if ((ip->ip_off & IP_OFFMASK) == 0) len += snprintf(SNPARGS(proto, len), ":%d ", ntohs(tcp->th_sport)); else len += snprintf(SNPARGS(proto, len), " "); len += snprintf(SNPARGS(proto, len), "%s", inet_ntoa(ip->ip_dst)); if ((ip->ip_off & IP_OFFMASK) == 0) snprintf(SNPARGS(proto, len), ":%d", ntohs(tcp->th_dport)); break; case IPPROTO_UDP: len = snprintf(SNPARGS(proto, 0), "UDP %s", inet_ntoa(ip->ip_src)); if ((ip->ip_off & IP_OFFMASK) == 0) len += snprintf(SNPARGS(proto, len), ":%d ", ntohs(udp->uh_sport)); else len += snprintf(SNPARGS(proto, len), " "); len += snprintf(SNPARGS(proto, len), "%s", inet_ntoa(ip->ip_dst)); if ((ip->ip_off & IP_OFFMASK) == 0) snprintf(SNPARGS(proto, len), ":%d", ntohs(udp->uh_dport)); break; case IPPROTO_ICMP: if ((ip->ip_off & IP_OFFMASK) == 0) len = snprintf(SNPARGS(proto, 0), "ICMP:%u.%u ", icmp->icmp_type, icmp->icmp_code); else len = snprintf(SNPARGS(proto, 0), "ICMP "); snprintf(SNPARGS(proto, len), "%s %s", inet_ntoa(ip->ip_src), inet_ntoa(ip->ip_dst)); break; default: snprintf(SNPARGS(proto, 0), "P:%d %s %s", ip->ip_p, inet_ntoa(ip->ip_src), inet_ntoa(ip->ip_dst)); break; } if ((ip->ip_off & IP_OFFMASK)) snprintf(SNPARGS(fragment, 0), " Fragment = %d", ip->ip_off & IP_OFFMASK); else fragment[0] = '\0'; if (oif) log(LOG_SECURITY | LOG_INFO, "%s %s %s out via %s%d%s\n", name, action, proto, oif->if_name, oif->if_unit, fragment); else if (rif) log(LOG_SECURITY | LOG_INFO, "%s %s %s in via %s%d%s\n", name, action, proto, rif->if_name, rif->if_unit, fragment); else log(LOG_SECURITY | LOG_INFO, "%s %s %s%s\n", name, action, proto, fragment); if ((f ? f->fw_logamount != 0 : 1) && count == (f ? f->fw_loghighest : fw_verbose_limit)) log(LOG_SECURITY | LOG_NOTICE, "ipfw: limit %d reached on entry %d\n", f ? f->fw_logamount : fw_verbose_limit, f ? f->fw_number : -1); } } /* * given an ip_fw_chain *, lookup_next_rule will return a pointer * of the same type to the next one. This can be either the jump * target (for skipto instructions) or the next one in the chain (in * all other cases including a missing jump target). * Backward jumps are not allowed, so start looking from the next * rule... */ static struct ip_fw_chain * lookup_next_rule(struct ip_fw_chain *me); static struct ip_fw_chain * lookup_next_rule(struct ip_fw_chain *me) { struct ip_fw_chain *chain ; int rule = me->rule->fw_skipto_rule ; /* guess... */ if ( (me->rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_SKIPTO ) for (chain = me->chain.le_next; chain ; chain = chain->chain.le_next ) if (chain->rule->fw_number >= rule) return chain ; return me->chain.le_next ; /* failure or not a skipto */ } /* * Parameters: * * pip Pointer to packet header (struct ip **) * bridge_ipfw extension: pip = NULL means a complete ethernet packet * including ethernet header in the mbuf. Other fields * are ignored/invalid. * * hlen Packet header length * oif Outgoing interface, or NULL if packet is incoming * *cookie Skip up to the first rule past this rule number; * *m The packet; we set to NULL when/if we nuke it. * *flow_id pointer to the last matching rule (in/out) * *next_hop socket we are forwarding to (in/out). * * 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, u_int16_t *cookie, struct mbuf **m, struct ip_fw_chain **flow_id, struct sockaddr_in **next_hop) { struct ip_fw_chain *chain; struct ip_fw *rule = NULL; struct ip *ip = NULL ; struct ifnet *const rif = (*m)->m_pkthdr.rcvif; u_short offset = 0 ; u_short src_port, dst_port; u_int16_t skipto = *cookie; if (pip) { /* normal ip packet */ ip = *pip; offset = (ip->ip_off & IP_OFFMASK); } else { /* bridged or non-ip packet */ struct ether_header *eh = mtod(*m, struct ether_header *); switch (ntohs(eh->ether_type)) { case ETHERTYPE_IP : if ((*m)->m_lenip_v != IPVERSION) goto non_ip ; hlen = ip->ip_hl << 2; if (hlen < sizeof(struct ip)) /* minimum header length */ goto non_ip ; if ((*m)->m_len < 14 + hlen + 14) { printf("-- m_len %d, need more...\n", (*m)->m_len); goto non_ip ; } offset = (ip->ip_off & IP_OFFMASK); break ; default : non_ip: ip = NULL ; break ; } } if (*flow_id) { if (fw_one_pass) return 0 ; /* accept if passed first test */ /* * pkt has already been tagged. Look for the next rule * to restart processing */ chain = LIST_NEXT( *flow_id, chain); if ( (chain = (*flow_id)->rule->next_rule_ptr) == NULL ) chain = (*flow_id)->rule->next_rule_ptr = lookup_next_rule(*flow_id) ; if (! chain) goto dropit; } else { /* * Go down the chain, looking for enlightment * If we've been asked to start at a given rule immediatly, do so. */ chain = LIST_FIRST(&ip_fw_chain); if ( skipto ) { if (skipto >= IPFW_DEFAULT_RULE) goto dropit; while (chain && (chain->rule->fw_number <= skipto)) { chain = LIST_NEXT(chain, chain); } if (! chain) goto dropit; } } *cookie = 0; for (; chain; chain = LIST_NEXT(chain, chain)) { register struct ip_fw * f ; again: 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; } if (ip == NULL ) { /* * do relevant checks for non-ip packets: * after this, only goto got_match or continue */ struct ether_header *eh = mtod(*m, struct ether_header *); /* * make default rule always match or we have a panic */ if (f->fw_number == IPFW_DEFAULT_RULE) goto got_match ; /* * temporary hack: * udp from 0.0.0.0 means this rule applies. * 1 src port is match ether type * 2 src ports (interval) is match ether type * 3 src ports is match ether address */ if ( f->fw_src.s_addr != 0 || f->fw_prot != IPPROTO_UDP || f->fw_smsk.s_addr != 0xffffffff ) continue; switch (IP_FW_GETNSRCP(f)) { case 1: /* match one type */ if ( /* ( (f->fw_flg & IP_FW_F_INVSRC) != 0) ^ */ ( f->fw_uar.fw_pts[0] == ntohs(eh->ether_type) ) ) { goto got_match ; } break ; default: break ; } continue ; } /* Fragments */ if ((f->fw_flg & IP_FW_F_FRAG) && offset == 0 ) 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, and no [ug]id, match */ if (f->fw_prot == IPPROTO_IP) { if (!(f->fw_flg & (IP_FW_F_UID|IP_FW_F_GID))) goto rnd_then_got_match; } else /* If different, don't match */ if (ip->ip_p != f->fw_prot) continue; /* * here, pip==NULL for bridged pkts -- they include the ethernet * header so i have to adjust lengths accordingly */ #define PULLUP_TO(l) do { \ int len = (pip ? l : l + 14 ) ; \ if ((*m)->m_len < (len) ) { \ if ( (*m = m_pullup(*m, (len))) == 0) \ goto bogusfrag; \ ip = mtod(*m, struct ip *); \ if (pip) \ *pip = ip ; \ else \ ip = (struct ip *)((char *)ip + 14);\ offset = (ip->ip_off & IP_OFFMASK); \ } \ } while (0) /* Protocol specific checks for uid only */ if (f->fw_flg & (IP_FW_F_UID|IP_FW_F_GID)) { switch (ip->ip_p) { case IPPROTO_TCP: { struct tcphdr *tcp; struct inpcb *P; if (offset == 1) /* cf. RFC 1858 */ goto bogusfrag; if (offset != 0) continue; PULLUP_TO(hlen + 14); tcp =(struct tcphdr *)((u_int32_t *)ip + ip->ip_hl); if (oif) P = in_pcblookup_hash(&tcbinfo, ip->ip_dst, tcp->th_dport, ip->ip_src, tcp->th_sport, 0); else P = in_pcblookup_hash(&tcbinfo, ip->ip_src, tcp->th_sport, ip->ip_dst, tcp->th_dport, 0); if (P && P->inp_socket) { if (f->fw_flg & IP_FW_F_UID) { if (P->inp_socket->so_cred->cr_uid != f->fw_uid) continue; } else if (!groupmember(f->fw_gid, P->inp_socket->so_cred)) continue; } else continue; break; } case IPPROTO_UDP: { struct udphdr *udp; struct inpcb *P; if (offset != 0) continue; PULLUP_TO(hlen + 4); udp =(struct udphdr *)((u_int32_t *)ip + ip->ip_hl); if (oif) P = in_pcblookup_hash(&udbinfo, ip->ip_dst, udp->uh_dport, ip->ip_src, udp->uh_sport, 1); else P = in_pcblookup_hash(&udbinfo, ip->ip_src, udp->uh_sport, ip->ip_dst, udp->uh_dport, 1); if (P && P->inp_socket) { if (f->fw_flg & IP_FW_F_UID) { if (P->inp_socket->so_cred->cr_uid != f->fw_uid) continue; } else if (!groupmember(f->fw_gid, P->inp_socket->so_cred)) continue; } else continue; break; } default: continue; /* * XXX Shouldn't GCC be allowing two bogusfrag labels if they're both inside * separate blocks? Hmm.... It seems it's got incorrect behavior here. */ #if 0 bogusfrag: if (fw_verbose) ipfw_report(NULL, ip, rif, oif); goto dropit; #endif } } /* 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_int32_t *)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_int32_t *)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_int32_t *)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; } rnd_then_got_match: if ( ((struct ip_fw_ext *)f)->dont_match_prob && random() < ((struct ip_fw_ext *)f)->dont_match_prob ) continue ; got_match: *flow_id = chain ; /* XXX set flow id */ /* Update statistics */ f->fw_pcnt += 1; if (ip) { 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; #ifdef IPDIVERT case IP_FW_F_DIVERT: *cookie = f->fw_number; 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; #endif case IP_FW_F_SKIPTO: /* XXX check */ if ( f->next_rule_ptr ) chain = f->next_rule_ptr ; else chain = lookup_next_rule(chain) ; if (! chain) goto dropit; goto again ; #ifdef DUMMYNET case IP_FW_F_PIPE: return(f->fw_pipe_nr | 0x10000 ); #endif #ifdef IPFIREWALL_FORWARD case IP_FW_F_FWD: /* Change the next-hop address for this packet. * Initially we'll only worry about directly * reachable next-hop's, but ultimately * we will work out for next-hops that aren't * direct the route we would take for it. We * [cs]ould leave this latter problem to * ip_output.c. We hope to high [name the abode of * your favourite deity] that ip_output doesn't modify * the new value of next_hop (which is dst there) */ if (next_hop != NULL) /* Make sure, first... */ *next_hop = &(f->fw_fwd_ip); return(0); /* Allow the packet */ #endif } /* Deny/reject this packet using this rule */ rule = f; break; } #ifdef DIAGNOSTIC /* Rule IPFW_DEFAULT_RULE 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->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_int32_t *)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. */ /* *cookie = 0; */ /* XXX is this necessary ? */ if (*m) { m_freem(*m); *m = NULL; } return(0); } /* * when a rule is added/deleted, zero the direct pointers within * all firewall rules. These will be reconstructed on the fly * as packets are matched. * Must be called at splnet(). */ static void flush_rule_ptrs() { struct ip_fw_chain *fcp ; for (fcp = ip_fw_chain.lh_first; fcp; fcp = fcp->chain.le_next) { fcp->rule->next_rule_ptr = NULL ; } } static int add_entry(struct ip_fw_head *chainptr, struct ip_fw *frwl) { struct ip_fw *ftmp = 0; struct ip_fw_ext *ftmp_ext = 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_ext = malloc(sizeof *ftmp_ext, M_IPFW, M_DONTWAIT); ftmp = &ftmp_ext->rule ; 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); } bzero(ftmp_ext, sizeof(*ftmp_ext)); /* play safe! */ bcopy(frwl, ftmp, sizeof(*ftmp)); if (ftmp->fw_flg & IP_FW_F_RND_MATCH) ftmp_ext->dont_match_prob = (intptr_t)ftmp->pipe_ptr; ftmp->fw_in_if.fu_via_if.name[FW_IFNLEN - 1] = '\0'; ftmp->fw_pcnt = 0L; ftmp->fw_bcnt = 0L; ftmp->next_rule_ptr = NULL ; ftmp->pipe_ptr = NULL ; fwc->rule = ftmp; s = splnet(); if (chainptr->lh_first == 0) { LIST_INSERT_HEAD(chainptr, fwc, chain); splx(s); return(0); } /* 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 < IPFW_DEFAULT_RULE - 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; } } flush_rule_ptrs(); 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); #ifdef DUMMYNET dn_rule_delete(fcp) ; #endif flush_rule_ptrs(); free(fcp->rule, M_IPFW); free(fcp, M_IPFW); fcp = next; } splx(s); return 0; } } } return (EINVAL); } static int zero_entry(struct ip_fw *frwl) { struct ip_fw_chain *fcp; int s, cleared; if (frwl == 0) { 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->fw_loghighest = fcp->rule->fw_logamount; fcp->rule->timestamp = 0; } splx(s); } else { 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->fw_loghighest = fcp->rule->fw_logamount; fcp->rule->timestamp = 0; fcp = LIST_NEXT(fcp, chain); } splx(s); cleared = 1; break; } if (!cleared) /* we didn't find any matching rules */ return (EINVAL); } if (fw_verbose) { if (frwl) log(LOG_SECURITY | LOG_NOTICE, "ipfw: Entry %d cleared.\n", frwl->fw_number); else log(LOG_SECURITY | LOG_NOTICE, "ipfw: Accounting cleared.\n"); } return (0); } static int resetlog_entry(struct ip_fw *frwl) { struct ip_fw_chain *fcp; int s, cleared; if (frwl == 0) { s = splnet(); counter = 0; for (fcp = LIST_FIRST(&ip_fw_chain); fcp; fcp = LIST_NEXT(fcp, chain)) fcp->rule->fw_loghighest = fcp->rule->fw_pcnt + fcp->rule->fw_logamount; splx(s); } else { 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_loghighest = fcp->rule->fw_pcnt + fcp->rule->fw_logamount; fcp = LIST_NEXT(fcp, chain); } splx(s); cleared = 1; break; } if (!cleared) /* we didn't find any matching rules */ return (EINVAL); } if (fw_verbose) { if (frwl) log(LOG_SECURITY | LOG_NOTICE, "ipfw: Entry %d logging count reset.\n", frwl->fw_number); else log(LOG_SECURITY | LOG_NOTICE, " ipfw: All logging counts cleared.\n"); } return (0); } static int 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 (EINVAL); } /* 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 (EINVAL); } /* 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 (EINVAL); } /* 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 (EINVAL); } /* 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 (EINVAL); } 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 (EINVAL); } 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 (EINVAL); } /* * 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 (EINVAL); } /* * 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 (EINVAL); } 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 (EINVAL); } if (frwl->fw_prot == IPPROTO_TCP && frwl->fw_tcpf != frwl->fw_tcpnf) { dprintf(("%s cannot mix 'frag' and TCP flags\n", err_prefix)); return (EINVAL); } } /* 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 (EINVAL); } break; #if defined(IPDIVERT) || defined(DUMMYNET) #ifdef IPDIVERT case IP_FW_F_DIVERT: /* Diverting to port zero is invalid */ case IP_FW_F_TEE: #endif #ifdef DUMMYNET case IP_FW_F_PIPE: /* piping through 0 is invalid */ #endif if (frwl->fw_divert_port == 0) { dprintf(("%s can't divert to port 0\n", err_prefix)); return (EINVAL); } break; #endif /* IPDIVERT || DUMMYNET */ case IP_FW_F_DENY: case IP_FW_F_ACCEPT: case IP_FW_F_COUNT: case IP_FW_F_SKIPTO: #ifdef IPFIREWALL_FORWARD case IP_FW_F_FWD: #endif case IP_FW_F_UID: case IP_FW_F_GID: break; default: dprintf(("%s invalid command\n", err_prefix)); return (EINVAL); } return 0; } static int ip_fw_ctl(struct sockopt *sopt) { int error, s; size_t size; struct ip_fw_chain *fcp; struct ip_fw frwl, *bp , *buf; /* * Disallow sets in really-really secure mode, but still allow * the logging counters to be reset. */ if (sopt->sopt_dir == SOPT_SET && securelevel >= 3 && sopt->sopt_name != IP_FW_RESETLOG) return (EPERM); error = 0; switch (sopt->sopt_name) { case IP_FW_GET: for (fcp = LIST_FIRST(&ip_fw_chain), size = 0; fcp; fcp = LIST_NEXT(fcp, chain)) size += sizeof *fcp->rule; buf = malloc(size, M_TEMP, M_WAITOK); if (buf == 0) { error = ENOBUFS; break; } for (fcp = LIST_FIRST(&ip_fw_chain), bp = buf; fcp; fcp = LIST_NEXT(fcp, chain)) { bcopy(fcp->rule, bp, sizeof *fcp->rule); bp->pipe_ptr = (void *)(intptr_t) ((struct ip_fw_ext *)fcp->rule)->dont_match_prob; bp++; } error = sooptcopyout(sopt, buf, size); FREE(buf, M_TEMP); break; case IP_FW_FLUSH: for (fcp = ip_fw_chain.lh_first; fcp != 0 && fcp->rule->fw_number != IPFW_DEFAULT_RULE; fcp = ip_fw_chain.lh_first) { s = splnet(); LIST_REMOVE(fcp, chain); #ifdef DUMMYNET dn_rule_delete(fcp); #endif FREE(fcp->rule, M_IPFW); FREE(fcp, M_IPFW); splx(s); } break; case IP_FW_ZERO: if (sopt->sopt_val != 0) { error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl); if (error || (error = zero_entry(&frwl))) break; } else { error = zero_entry(0); } break; case IP_FW_ADD: error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl); if (error || (error = check_ipfw_struct(&frwl))) break; if (frwl.fw_number == IPFW_DEFAULT_RULE) { dprintf(("%s can't add rule %u\n", err_prefix, (unsigned)IPFW_DEFAULT_RULE)); error = EINVAL; } else { error = add_entry(&ip_fw_chain, &frwl); } break; case IP_FW_DEL: error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl); if (error) break; if (frwl.fw_number == IPFW_DEFAULT_RULE) { dprintf(("%s can't delete rule %u\n", err_prefix, (unsigned)IPFW_DEFAULT_RULE)); error = EINVAL; } else { error = del_entry(&ip_fw_chain, frwl.fw_number); } break; case IP_FW_RESETLOG: if (sopt->sopt_val != 0) { error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl); if (error || (error = resetlog_entry(&frwl))) break; } else { error = resetlog_entry(0); } break; default: printf("ip_fw_ctl invalid option %d\n", sopt->sopt_name); error = EINVAL ; } return (error); } struct ip_fw_chain *ip_fw_default_rule ; 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 = IPFW_DEFAULT_RULE; #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) != 0 || add_entry(&ip_fw_chain, &default_rule)) panic("ip_fw_init"); ip_fw_default_rule = ip_fw_chain.lh_first ; printf("IP packet filtering initialized, " #ifdef IPDIVERT "divert enabled, "); #else "divert disabled, "); #endif #ifdef IPFIREWALL_FORWARD printf("rule-based forwarding enabled, "); #else printf("rule-based forwarding 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 by default\n", fw_verbose_limit); #endif } static ip_fw_chk_t *old_chk_ptr; static ip_fw_ctl_t *old_ctl_ptr; static int ipfw_modevent(module_t mod, int type, void *unused) { int s; switch (type) { case MOD_LOAD: s = splnet(); old_chk_ptr = ip_fw_chk_ptr; old_ctl_ptr = ip_fw_ctl_ptr; ip_fw_init(); splx(s); return 0; case MOD_UNLOAD: 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); return 0; default: break; } return 0; } static moduledata_t ipfwmod = { "ipfw", ipfw_modevent, 0 }; DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY);