/* * Copyright (c) 1993 Daniel Boulet * Copyright (c) 1994 Ugen J.S.Antsilevich * Copyright (c) 1996 Alex Nash * Copyright (c) 2000-2001 Luigi Rizzo * * 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. * * $FreeBSD$ */ #define DEB(x) #define DDB(x) x /* * 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 #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 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 int fw_permanent_rules = 0; /* * Right now, two fields in the IP header are changed to host format * by the IP layer before calling the firewall. Ideally, we would like * to have them in network format so that the packet can be * used as it comes from the device driver (and is thus readonly). */ static u_int64_t counter; /* counter for ipfw_report(NULL...) */ struct ipfw_flow_id last_pkt ; #define IPFW_DEFAULT_RULE ((u_int)(u_short)~0) LIST_HEAD (ip_fw_head, ip_fw) ip_fw_chain_head; MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); #ifdef SYSCTL_NODE SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW, &fw_enable, 0, "Enable ipfw"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW, &fw_one_pass, 0, "Only do a single pass through ipfw when using dummynet(4)"); 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, 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"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, permanent_rules, CTLFLAG_RW, &fw_permanent_rules, 0, "Set rule number, below which rules are permanent"); /* * Extension for stateful ipfw. * * Dynamic rules are stored in lists accessed through a hash table * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can * be modified through the sysctl variable dyn_buckets which is * updated when the table becomes empty. * * XXX currently there is only one list, ipfw_dyn. * * When a packet is received, it is first hashed, then matched * against the entries in the corresponding list. * Matching occurs according to the rule type. The default is to * match the four fields and the protocol, and rules are bidirectional. * * For a busy proxy/web server we will have lots of connections to * the server. We could decide for a rule type where we ignore * ports (different hashing) and avoid special SYN/RST/FIN handling. * * XXX when we decide to support more than one rule type, we should * repeat the hashing multiple times uing only the useful fields. * Or, we could run the various tests in parallel, because the * 'move to front' technique should shorten the average search. * * The lifetime of dynamic rules is regulated by dyn_*_lifetime, * measured in seconds and depending on the flags. * * The total number of dynamic rules is stored in dyn_count. * The max number of dynamic rules is dyn_max. When we reach * the maximum number of rules we do not create anymore. This is * done to avoid consuming too much memory, but also too much * time when searching on each packet (ideally, we should try instead * to put a limit on the length of the list on each bucket...). * * Each dynamic rules holds a pointer to the parent ipfw rule so * we know what action to perform. Dynamic rules are removed when * the parent rule is deleted. * There are some limitations with dynamic rules -- we do not * obey the 'randomized match', and we do not do multiple * passes through the firewall. * XXX check the latter!!! */ static struct ipfw_dyn_rule **ipfw_dyn_v = NULL ; static u_int32_t dyn_buckets = 256 ; /* must be power of 2 */ static u_int32_t curr_dyn_buckets = 256 ; /* must be power of 2 */ /** * timeouts for various events in handing dynamic rules. */ static u_int32_t dyn_ack_lifetime = 300 ; static u_int32_t dyn_syn_lifetime = 20 ; static u_int32_t dyn_fin_lifetime = 1 ; static u_int32_t dyn_rst_lifetime = 1 ; static u_int32_t dyn_udp_lifetime = 10 ; static u_int32_t dyn_short_lifetime = 5 ; /* * after reaching 0, dynamic rules are considered still valid for * an additional grace time, unless there is lack of resources. */ static u_int32_t dyn_grace_time = 10 ; static u_int32_t static_count = 0 ; /* # of static rules */ static u_int32_t dyn_count = 0 ; /* # of dynamic rules */ static u_int32_t dyn_max = 1000 ; /* max # of dynamic rules */ SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW, &dyn_buckets, 0, "Number of dyn. buckets"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD, &curr_dyn_buckets, 0, "Current Number of dyn. buckets"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD, &dyn_count, 0, "Number of dyn. rules"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW, &dyn_max, 0, "Max number of dyn. rules"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD, &static_count, 0, "Number of static rules"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW, &dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW, &dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW, &dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW, &dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW, &dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW, &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations"); SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_grace_time, CTLFLAG_RD, &dyn_grace_time, 0, "Grace time for dyn. rules"); #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 (struct ip_fw_head *chainptr, struct ip_fw *frwl); static int del_entry (struct ip_fw_head *chainptr, u_short number); static int zero_entry (struct ip_fw *, int); static int check_ipfw_struct (struct ip_fw *m); static int iface_match (struct ifnet *ifp, union ip_fw_if *ifu, int byname); static int ipopts_match (struct ip *ip, struct ip_fw *f); static int iptos_match (struct ip *ip, struct ip_fw *f); static __inline int port_match (u_short *portptr, int nports, u_short port, int range_flag, int mask); static int tcpflg_match (struct tcphdr *tcp, struct ip_fw *f); static int icmptype_match (struct icmp * icmp, struct ip_fw * f); static void ipfw_report (struct ip_fw *f, struct ip *ip, int offset, int ip_len, struct ifnet *rif, struct ifnet *oif); static void flush_rule_ptrs(void); static int ip_fw_chk (struct ip **pip, int hlen, struct ifnet *oif, u_int16_t *cookie, struct mbuf **m, struct ip_fw **flow_id, struct sockaddr_in **next_hop); static int ip_fw_ctl (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, int mask) { if (!nports) return 1; if (mask) { if ( 0 == ((portptr[0] ^ port) & portptr[1]) ) return 1; nports -= 2; portptr += 2; } 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 an established connection is required, reject packets that * have only SYN of RST|ACK|SYN set. Otherwise, fall through to * other flag requirements. */ if ((f->fw_ipflg & IP_FW_IF_TCPEST) && ((tcp->th_flags & (IP_FW_TCPF_RST | IP_FW_TCPF_ACK | IP_FW_TCPF_SYN)) == IP_FW_TCPF_SYN)) return 0; 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 int iptos_match(struct ip *ip, struct ip_fw *f) { u_int flags = (ip->ip_tos & 0x1f); u_char opts, nopts, nopts_sve; opts = f->fw_iptos; nopts = nopts_sve = f->fw_ipntos; while (flags != 0) { u_int flag; flag = 1 << (ffs(flags) -1); opts &= ~flag; nopts &= ~flag; flags &= ~flag; } if (opts == 0 && nopts == nopts_sve) return 1; else return 0; } static int tcpopts_match(struct tcphdr *tcp, struct ip_fw *f) { register u_char *cp; int opt, optlen, cnt; u_char opts, nopts, nopts_sve; cp = (u_char *)(tcp + 1); cnt = (tcp->th_off << 2) - sizeof (struct tcphdr); opts = f->fw_tcpopt; nopts = nopts_sve = f->fw_tcpnopt; for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[0]; if (opt == TCPOPT_EOL) break; if (opt == TCPOPT_NOP) optlen = 1; else { optlen = cp[1]; if (optlen <= 0) break; } switch (opt) { default: break; case TCPOPT_MAXSEG: opts &= ~IP_FW_TCPOPT_MSS; nopts &= ~IP_FW_TCPOPT_MSS; break; case TCPOPT_WINDOW: opts &= ~IP_FW_TCPOPT_WINDOW; nopts &= ~IP_FW_TCPOPT_WINDOW; break; case TCPOPT_SACK_PERMITTED: case TCPOPT_SACK: opts &= ~IP_FW_TCPOPT_SACK; nopts &= ~IP_FW_TCPOPT_SACK; break; case TCPOPT_TIMESTAMP: opts &= ~IP_FW_TCPOPT_TS; nopts &= ~IP_FW_TCPOPT_TS; break; case TCPOPT_CC: case TCPOPT_CCNEW: case TCPOPT_CCECHO: opts &= ~IP_FW_TCPOPT_CC; nopts &= ~IP_FW_TCPOPT_CC; break; } if (opts == nopts) break; } if (opts == 0 && nopts == nopts_sve) return 1; else return 0; } static 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; TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { 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, int offset, int ip_len, struct ifnet *rif, struct ifnet *oif) { 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[27]; 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; case IP_FW_F_QUEUE: snprintf(SNPARGS(action2, 0), "Queue %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; } } switch (ip->ip_p) { case IPPROTO_TCP: len = snprintf(SNPARGS(proto, 0), "TCP %s", inet_ntoa(ip->ip_src)); if (offset == 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 (offset == 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 (offset == 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 (offset == 0) snprintf(SNPARGS(proto, len), ":%d", ntohs(udp->uh_dport)); break; case IPPROTO_ICMP: if (offset == 0) len = snprintf(SNPARGS(proto, 0), "ICMP:%u.%u ", icmp->icmp_type, icmp->icmp_code); else len = snprintf(SNPARGS(proto, 0), "ICMP "); len += snprintf(SNPARGS(proto, len), "%s", inet_ntoa(ip->ip_src)); snprintf(SNPARGS(proto, len), " %s", inet_ntoa(ip->ip_dst)); break; default: len = snprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p, inet_ntoa(ip->ip_src)); snprintf(SNPARGS(proto, len), " %s", inet_ntoa(ip->ip_dst)); break; } if (ip->ip_off & (IP_MF | IP_OFFMASK)) snprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)", ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2), offset << 3, (ip->ip_off & IP_MF) ? "+" : ""); 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); } static __inline int hash_packet(struct ipfw_flow_id *id) { u_int32_t i ; i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); i &= (curr_dyn_buckets - 1) ; return i ; } /** * unlink a dynamic rule from a chain. prev is a pointer to * the previous one, q is a pointer to the rule to delete, * head is a pointer to the head of the queue. * Modifies q and potentially also head. */ #define UNLINK_DYN_RULE(prev, head, q) { \ struct ipfw_dyn_rule *old_q = q; \ \ /* remove a refcount to the parent */ \ if (q->dyn_type == DYN_LIMIT) \ q->parent->count--; \ DEB(printf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n", \ (q->id.src_ip), (q->id.src_port), \ (q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); ) \ if (prev != NULL) \ prev->next = q = q->next ; \ else \ ipfw_dyn_v[i] = q = q->next ; \ dyn_count-- ; \ free(old_q, M_IPFW); } #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) /** * Remove all dynamic rules pointing to a given rule, or all * rules if rule == NULL. Second parameter is 1 if we want to * delete unconditionally, otherwise only expired rules are removed. */ static void remove_dyn_rule(struct ip_fw *rule, int force) { struct ipfw_dyn_rule *prev, *q; int i, pass, max_pass ; static u_int32_t last_remove = 0 ; if (ipfw_dyn_v == NULL || dyn_count == 0) return ; /* do not expire more than once per second, it is useless */ if (force == 0 && last_remove == time_second) return ; last_remove = time_second ; /* * because DYN_LIMIT refer to parent rules, during the first pass only * remove child and mark any pending LIMIT_PARENT, and remove * them in a second pass. */ for (pass = max_pass = 0; pass <= max_pass ; pass++ ) { for (i = 0 ; i < curr_dyn_buckets ; i++) { for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) { /* * logic can become complex here, so we split tests. * First, test if we match any rule, * then make sure the rule is expired or we want to kill it, * and possibly more in the future. */ int zap = ( rule == NULL || rule == q->rule); if (zap) zap = force || TIME_LEQ( q->expire , time_second ); /* do not zap parent in first pass, record we need a second pass */ if (q->dyn_type == DYN_LIMIT_PARENT) { max_pass = 1; /* we need a second pass */ if (zap == 1 && (pass == 0 || q->count != 0) ) { zap = 0 ; if (q->count != 0) printf("cannot remove parent, count %d\n", q->count); } } if (zap) { UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); } else { prev = q ; q = q->next ; } } } } } #define EXPIRE_DYN_CHAIN(rule) remove_dyn_rule(rule, 0 /* expired ones */) #define EXPIRE_DYN_CHAINS() remove_dyn_rule(NULL, 0 /* expired ones */) #define DELETE_DYN_CHAIN(rule) remove_dyn_rule(rule, 1 /* force removal */) #define DELETE_DYN_CHAINS() remove_dyn_rule(NULL, 1 /* force removal */) /** * lookup a dynamic rule. */ static struct ipfw_dyn_rule * lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction) { /* * stateful ipfw extensions. * Lookup into dynamic session queue */ struct ipfw_dyn_rule *prev, *q ; int i, dir = 0; #define MATCH_FORWARD 1 if (ipfw_dyn_v == NULL) return NULL ; i = hash_packet( pkt ); for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { if (q->dyn_type == DYN_LIMIT_PARENT) goto next; if (TIME_LEQ( q->expire , time_second ) ) { /* expire entry */ UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); continue ; } if ( pkt->proto == q->id.proto) { if (pkt->src_ip == q->id.src_ip && pkt->dst_ip == q->id.dst_ip && pkt->src_port == q->id.src_port && pkt->dst_port == q->id.dst_port ) { dir = MATCH_FORWARD ; goto found ; } if (pkt->src_ip == q->id.dst_ip && pkt->dst_ip == q->id.src_ip && pkt->src_port == q->id.dst_port && pkt->dst_port == q->id.src_port ) { dir = 0 ; /* reverse match */ goto found ; } } next: prev = q ; q = q->next ; } return NULL ; /* clearly not found */ found: if ( prev != NULL) { /* found and not in front */ prev->next = q->next ; q->next = ipfw_dyn_v[i] ; ipfw_dyn_v[i] = q ; } if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST); q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); switch (q->state) { case TH_SYN : /* opening */ q->expire = time_second + dyn_syn_lifetime ; break ; case TH_SYN | (TH_SYN << 8) : /* move to established */ q->expire = time_second + dyn_ack_lifetime ; break ; case TH_SYN | (TH_SYN << 8) | TH_FIN : case TH_SYN | (TH_SYN << 8) | (TH_FIN << 8) : /* one side tries to close */ q->expire = time_second + dyn_ack_lifetime ; break ; case TH_SYN | (TH_SYN << 8) | TH_FIN | (TH_FIN << 8) : /* both sides closed */ q->expire = time_second + dyn_fin_lifetime ; break ; default: #if 0 /* * reset or some invalid combination, but can also * occur if we use keep-state the wrong way. */ if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) printf("invalid state: 0x%x\n", q->state); #endif q->expire = time_second + dyn_rst_lifetime ; break ; } } else if (pkt->proto == IPPROTO_UDP) { q->expire = time_second + dyn_udp_lifetime ; } else { /* other protocols */ q->expire = time_second + dyn_short_lifetime ; } if (match_direction) *match_direction = dir ; return q ; } /** * Install state of type 'type' for a dynamic session. * The hash table contains two type of rules: * - regular rules (DYN_KEEP_STATE) * - rules for sessions with limited number of sess per user * (DYN_LIMIT). When they are created, the parent is * increased by 1, and decreased on delete. In this case, * the third parameter is the parent rule and not the chain. * - "parent" rules for the above (DYN_LIMIT_PARENT). */ static struct ipfw_dyn_rule * add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) { struct ipfw_dyn_rule *r ; int i ; if (ipfw_dyn_v == NULL || (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { /* try reallocation, make sure we have a power of 2 */ u_int32_t i = dyn_buckets ; while ( i > 0 && (i & 1) == 0 ) i >>= 1 ; if (i != 1) /* not a power of 2 */ dyn_buckets = curr_dyn_buckets ; /* reset */ else { curr_dyn_buckets = dyn_buckets ; if (ipfw_dyn_v != NULL) free(ipfw_dyn_v, M_IPFW); ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof r, M_IPFW, M_DONTWAIT | M_ZERO); if (ipfw_dyn_v == NULL) return NULL; /* failed ! */ } } i = hash_packet(id); r = malloc(sizeof *r, M_IPFW, M_DONTWAIT | M_ZERO); if (r == NULL) { printf ("sorry cannot allocate state\n"); return NULL ; } /* increase refcount on parent, and set pointer */ if (dyn_type == DYN_LIMIT) { struct ipfw_dyn_rule *parent = (struct ipfw_dyn_rule *)rule; if ( parent->dyn_type != DYN_LIMIT_PARENT) panic("invalid parent"); parent->count++ ; r->parent = parent ; rule = parent->rule; } r->id = *id ; r->expire = time_second + dyn_syn_lifetime ; r->rule = rule ; r->dyn_type = dyn_type ; r->pcnt = r->bcnt = 0 ; r->count = 0 ; r->bucket = i ; r->next = ipfw_dyn_v[i] ; ipfw_dyn_v[i] = r ; dyn_count++ ; DEB(printf("-- add entry 0x%08x %d -> 0x%08x %d, total %d\n", (r->id.src_ip), (r->id.src_port), (r->id.dst_ip), (r->id.dst_port), dyn_count ); ) return r; } /** * lookup dynamic parent rule using pkt and chain as search keys. * If the lookup fails, then install one. */ static struct ipfw_dyn_rule * lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) { struct ipfw_dyn_rule *q; int i; if (ipfw_dyn_v) { i = hash_packet( pkt ); for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next) if (q->dyn_type == DYN_LIMIT_PARENT && rule == q->rule && pkt->proto == q->id.proto && pkt->src_ip == q->id.src_ip && pkt->dst_ip == q->id.dst_ip && pkt->src_port == q->id.src_port && pkt->dst_port == q->id.dst_port) { q->expire = time_second + dyn_short_lifetime ; DEB(printf("lookup_dyn_parent found 0x%p\n", q);) return q; } } return add_dyn_rule(pkt, DYN_LIMIT_PARENT, rule); } /* * Install dynamic state. * There are different types of dynamic rules which can be installed. * The type is in rule->dyn_type. * Type 0 (default) is a bidirectional rule * * Returns 1 (failure) if state is not installed because of errors or because * session limitations are enforced. */ static int install_state(struct ip_fw *rule) { struct ipfw_dyn_rule *q ; static int last_log ; u_int8_t type = rule->dyn_type ; DEB(printf("-- install state type %d 0x%08x %u -> 0x%08x %u\n", type, (last_pkt.src_ip), (last_pkt.src_port), (last_pkt.dst_ip), (last_pkt.dst_port) );) q = lookup_dyn_rule(&last_pkt, NULL) ; if (q != NULL) { /* should never occur */ if (last_log != time_second) { last_log = time_second ; printf(" entry already present, done\n"); } return 0 ; } if (dyn_count >= dyn_max) /* try remove old ones... */ EXPIRE_DYN_CHAINS(); if (dyn_count >= dyn_max) { if (last_log != time_second) { last_log = time_second ; printf(" Too many dynamic rules, sorry\n"); } return 1; /* cannot install, notify caller */ } switch (type) { case DYN_KEEP_STATE: /* bidir rule */ add_dyn_rule(&last_pkt, DYN_KEEP_STATE, rule); break ; case DYN_LIMIT: /* limit number of sessions */ { u_int16_t limit_mask = rule->limit_mask ; u_int16_t conn_limit = rule->conn_limit ; struct ipfw_flow_id id; struct ipfw_dyn_rule *parent; DEB(printf("installing dyn-limit rule %d\n", conn_limit);) id.dst_ip = id.src_ip = 0; id.dst_port = id.src_port = 0 ; id.proto = last_pkt.proto ; if (limit_mask & DYN_SRC_ADDR) id.src_ip = last_pkt.src_ip; if (limit_mask & DYN_DST_ADDR) id.dst_ip = last_pkt.dst_ip; if (limit_mask & DYN_SRC_PORT) id.src_port = last_pkt.src_port; if (limit_mask & DYN_DST_PORT) id.dst_port = last_pkt.dst_port; parent = lookup_dyn_parent(&id, rule); if (parent == NULL) { printf("add parent failed\n"); return 1; } if (parent->count >= conn_limit) { EXPIRE_DYN_CHAIN(rule); /* try to expire some */ if (parent->count >= conn_limit) { printf("drop session, too many entries\n"); return 1; } } add_dyn_rule(&last_pkt, DYN_LIMIT, (struct ip_fw *)parent); } break ; default: printf("unknown dynamic rule type %u\n", type); return 1 ; } lookup_dyn_rule(&last_pkt, NULL) ; /* XXX just set the lifetime */ return 0; } /* * given an ip_fw *, 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 * lookup_next_rule(struct ip_fw *me); static struct ip_fw * lookup_next_rule(struct ip_fw *me) { struct ip_fw *rule ; int rulenum = me->fw_skipto_rule ; /* guess... */ if ( (me->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_SKIPTO ) for (rule = LIST_NEXT(me,next); rule ; rule = LIST_NEXT(rule,next)) if (rule->fw_number >= rulenum) return rule ; return LIST_NEXT(me,next) ; /* failure or not a skipto */ } /* * Parameters: * * pip Pointer to packet header (struct ip **) * hlen Packet header length * oif Outgoing interface, or NULL if packet is incoming * *cookie Skip up to the first rule past this rule number; * upon return, non-zero port number for divert or tee. * Special case: cookie == NULL on input for bridging. * *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: * * IP_FW_PORT_DENY_FLAG the packet must be dropped. * 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, with these caveats: * * - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead * of diverting it (ie, 'ipfw tee'). * * - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower * 16 bits as a dummynet pipe number instead of diverting */ static int ip_fw_chk(struct ip **pip, int hlen, struct ifnet *oif, u_int16_t *cookie, struct mbuf **m, struct ip_fw **flow_id, struct sockaddr_in **next_hop) { struct ip_fw *f = NULL; /* matching rule */ struct ip *ip = *pip; struct ifnet *const rif = (*m)->m_pkthdr.rcvif; struct ifnet *tif; u_short offset = 0 ; u_short src_port = 0, dst_port = 0; struct in_addr src_ip, dst_ip; /* XXX */ u_int8_t proto= 0, flags = 0 ; /* XXX */ u_int16_t skipto, bridgeCookie; u_int16_t ip_len; int dyn_checked = 0 ; /* set after dyn.rules have been checked. */ int direction = MATCH_FORWARD ; /* dirty trick... */ struct ipfw_dyn_rule *q = NULL ; /* Special hack for bridging (as usual) */ if (cookie == NULL) { bridgeCookie = 0; cookie = &bridgeCookie; #define BRIDGED (cookie == &bridgeCookie) hlen = ip->ip_hl << 2; } /* Grab and reset cookie */ skipto = *cookie; *cookie = 0; #define PULLUP_TO(len) do { \ if ((*m)->m_len < (len)) { \ ip = NULL ; \ if ((*m = m_pullup(*m, (len))) == 0) \ goto bogusfrag; \ ip = mtod(*m, struct ip *); \ *pip = ip; \ } \ } while (0) /* * Collect parameters into local variables for faster matching. */ proto = ip->ip_p; src_ip = ip->ip_src; dst_ip = ip->ip_dst; if (0 && BRIDGED) { /* not yet... */ offset = (ntohs(ip->ip_off) & IP_OFFMASK); ip_len = ntohs(ip->ip_len); } else { offset = (ip->ip_off & IP_OFFMASK); ip_len = ip->ip_len; } if (offset == 0) { switch (proto) { case IPPROTO_TCP : { struct tcphdr *tcp; PULLUP_TO(hlen + sizeof(struct tcphdr)); tcp =(struct tcphdr *)((u_int32_t *)ip + ip->ip_hl); dst_port = tcp->th_dport ; src_port = tcp->th_sport ; flags = tcp->th_flags ; } break ; case IPPROTO_UDP : { struct udphdr *udp; PULLUP_TO(hlen + sizeof(struct udphdr)); udp =(struct udphdr *)((u_int32_t *)ip + ip->ip_hl); dst_port = udp->uh_dport ; src_port = udp->uh_sport ; } break; case IPPROTO_ICMP: PULLUP_TO(hlen + 4); /* type, code and checksum. */ flags = ((struct icmp *) ((u_int32_t *)ip + ip->ip_hl))->icmp_type ; break ; default : break; } } #undef PULLUP_TO last_pkt.src_ip = ntohl(src_ip.s_addr); last_pkt.dst_ip = ntohl(dst_ip.s_addr); last_pkt.proto = proto; last_pkt.src_port = ntohs(src_port); last_pkt.dst_port = ntohs(dst_port); last_pkt.flags = flags; if (*flow_id) { /* * Packet has already been tagged. Look for the next rule * to restart processing. */ if (fw_one_pass) /* just accept if fw_one_pass is set */ return 0; f = (*flow_id)->next_rule_ptr ; if (f == NULL) f = (*flow_id)->next_rule_ptr = lookup_next_rule(*flow_id); if (f == NULL) goto dropit; } else { /* * Go down the chain, looking for enlightment. * If we've been asked to start at a given rule, do so. */ f = LIST_FIRST(&ip_fw_chain_head); if (skipto != 0) { if (skipto >= IPFW_DEFAULT_RULE) goto dropit; while (f && f->fw_number <= skipto) f = LIST_NEXT(f, next); if (f == NULL) goto dropit; } } for (; f; f = LIST_NEXT(f, next)) { again: if (f->fw_number == IPFW_DEFAULT_RULE) goto got_match ; /* * dynamic rules are checked at the first keep-state or * check-state occurrence. */ if (f->fw_flg & (IP_FW_F_KEEP_S|IP_FW_F_CHECK_S) && dyn_checked == 0 ) { dyn_checked = 1 ; q = lookup_dyn_rule(&last_pkt, &direction); if (q != NULL) { DEB(printf("-- dynamic match 0x%08x %d %s 0x%08x %d\n", (q->id.src_ip), (q->id.src_port), (direction == MATCH_FORWARD ? "-->" : "<--"), (q->id.dst_ip), (q->id.dst_port) ); ) f = q->rule ; q->pcnt++ ; q->bcnt += ip_len; goto got_match ; /* random not allowed here */ } /* if this was a check-only rule, continue with next */ if (f->fw_flg & IP_FW_F_CHECK_S) continue ; } /* Check if rule only valid for bridged packets */ if ((f->fw_flg & IP_FW_BRIDGED) != 0 && !(BRIDGED)) continue; if (oif) { /* Check direction outbound */ if (!(f->fw_flg & IP_FW_F_OUT)) continue; } else { /* Check direction inbound */ if (!(f->fw_flg & IP_FW_F_IN)) continue; } /* Fragments */ if ((f->fw_flg & IP_FW_F_FRAG) && offset == 0 ) continue; if (f->fw_flg & IP_FW_F_SME) { INADDR_TO_IFP(src_ip, tif); if (tif == NULL) continue; } if (f->fw_flg & IP_FW_F_DME) { INADDR_TO_IFP(dst_ip, tif); if (tif == NULL) continue; } /* If src-addr doesn't match, not this rule. */ if (((f->fw_flg & IP_FW_F_INVSRC) != 0) ^ ((src_ip.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) ^ ((dst_ip.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 header values */ if (f->fw_ipflg & IP_FW_IF_IPOPT && !ipopts_match(ip, f)) continue; if (f->fw_ipflg & IP_FW_IF_IPLEN && f->fw_iplen != ip_len) continue; if (f->fw_ipflg & IP_FW_IF_IPID && f->fw_ipid != ntohs(ip->ip_id)) continue; if (f->fw_ipflg & IP_FW_IF_IPTOS && !iptos_match(ip, f)) continue; if (f->fw_ipflg & IP_FW_IF_IPTTL && f->fw_ipttl != ip->ip_ttl) continue; if (f->fw_ipflg & IP_FW_IF_IPVER && f->fw_ipver != ip->ip_v) 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 (proto != f->fw_prot) continue; /* Protocol specific checks for uid only */ if (f->fw_flg & (IP_FW_F_UID|IP_FW_F_GID)) { switch (proto) { case IPPROTO_TCP: { struct inpcb *P; if (offset == 1) /* cf. RFC 1858 */ goto bogusfrag; if (offset != 0) continue; if (oif) P = in_pcblookup_hash(&tcbinfo, dst_ip, dst_port, src_ip, src_port, 0, oif); else P = in_pcblookup_hash(&tcbinfo, src_ip, src_port, dst_ip, dst_port, 0, NULL); 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 inpcb *P; if (offset != 0) continue; if (oif) P = in_pcblookup_hash(&udbinfo, dst_ip, dst_port, src_ip, src_port, 1, oif); else P = in_pcblookup_hash(&udbinfo, src_ip, src_port, dst_ip, dst_port, 1, NULL); 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; } } /* Protocol specific checks */ switch (proto) { 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 (IP_FW_HAVEPORTS(f) != 0 || f->fw_ipflg & IP_FW_IF_TCPMSK) continue; break; } tcp = (struct tcphdr *) ((u_int32_t *)ip + ip->ip_hl); if (f->fw_ipflg & IP_FW_IF_TCPOPT && !tcpopts_match(tcp, f)) continue; if (((f->fw_ipflg & IP_FW_IF_TCPFLG) || (f->fw_ipflg & IP_FW_IF_TCPEST)) && !tcpflg_match(tcp, f)) continue; if (f->fw_ipflg & IP_FW_IF_TCPSEQ && tcp->th_seq != f->fw_tcpseq) continue; if (f->fw_ipflg & IP_FW_IF_TCPACK && tcp->th_ack != f->fw_tcpack) continue; if (f->fw_ipflg & IP_FW_IF_TCPWIN && tcp->th_win != f->fw_tcpwin) continue; goto check_ports; } case IPPROTO_UDP: if (offset != 0) { /* * Port specification is unavailable -- if this * rule specifies a port, we consider the rule * a non-match. */ if (IP_FW_HAVEPORTS(f) ) continue; break; } check_ports: if (!port_match(&f->fw_uar.fw_pts[0], IP_FW_GETNSRCP(f), ntohs(src_port), f->fw_flg & IP_FW_F_SRNG, f->fw_flg & IP_FW_F_SMSK)) continue; if (!port_match(&f->fw_uar.fw_pts[IP_FW_GETNSRCP(f)], IP_FW_GETNDSTP(f), ntohs(dst_port), f->fw_flg & IP_FW_F_DRNG, f->fw_flg & IP_FW_F_DMSK)) continue; break; case IPPROTO_ICMP: { struct icmp *icmp; if (offset != 0) /* Type isn't valid */ break; icmp = (struct icmp *) ((u_int32_t *)ip + ip->ip_hl); if (!icmptype_match(icmp, f)) continue; break; } default: break; bogusfrag: if (fw_verbose && ip != NULL) ipfw_report(NULL, ip, offset, ip_len, rif, oif); goto dropit; } rnd_then_got_match: if ( f->dont_match_prob && random() < f->dont_match_prob ) continue ; got_match: /* * If not a dynamic match (q == NULL) and keep-state, install * a new dynamic entry. */ if (q == NULL && f->fw_flg & IP_FW_F_KEEP_S) { if (install_state(f)) /* error or limit violation */ goto dropit; } /* Update statistics */ f->fw_pcnt += 1; f->fw_bcnt += 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, offset, ip_len, 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: *cookie = f->fw_number; return(f->fw_divert_port | IP_FW_PORT_TEE_FLAG); #endif case IP_FW_F_SKIPTO: /* XXX check */ f = f->next_rule_ptr ? f->next_rule_ptr : lookup_next_rule(f) ; if (!f) goto dropit; goto again ; #ifdef DUMMYNET case IP_FW_F_PIPE: case IP_FW_F_QUEUE: *flow_id = f; return(f->fw_pipe_nr | IP_FW_PORT_DYNT_FLAG); #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) * XXX warning-- there is a dangerous reference here * from next_hop to a field within the rule. If the * rule is deleted, weird things might occur. */ if (next_hop != NULL /* Make sure, first... */ && (q == NULL || direction == MATCH_FORWARD) ) *next_hop = &(f->fw_fwd_ip); return(0); /* Allow the packet */ #endif } /* Deny/reject this packet using this rule */ break; } /* Rule IPFW_DEFAULT_RULE should always be there and match */ KASSERT(f != NULL, ("ip_fw: no chain")); /* * 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 ((f->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_REJECT && (proto != IPPROTO_ICMP || is_icmp_query(ip)) && !((*m)->m_flags & (M_BCAST|M_MCAST)) && !IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { switch (f->fw_reject_code) { case IP_FW_REJECT_RST: { /* XXX warning, this code writes into the mbuf */ 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_len - hlen - (tip->ti_off << 2); if (tcp->th_flags & TH_ACK) { tcp_respond(NULL, (void *)ip, tcp, *m, (tcp_seq)0, tcp->th_ack, TH_RST); } else { if (tcp->th_flags & TH_SYN) tip->ti_len++; tcp_respond(NULL, (void *)ip, tcp, *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, f->fw_reject_code, 0L, 0); *m = NULL; break; } } dropit: /* * Finally, drop the packet. */ return(IP_FW_PORT_DENY_FLAG); #undef BRIDGED } /* * 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 *fcp ; LIST_FOREACH(fcp, &ip_fw_chain_head, next) { fcp->next_rule_ptr = NULL ; } } static int add_entry(struct ip_fw_head *head, struct ip_fw *rule) { struct ip_fw *ftmp, *fcp, *fcpl; u_short nbr = 0; int s; ftmp = malloc(sizeof *ftmp, M_IPFW, M_DONTWAIT | M_ZERO); if (!ftmp) return (ENOSPC); bcopy(rule, ftmp, sizeof(*ftmp)); 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 ; s = splnet(); if (LIST_FIRST(head) == 0) { LIST_INSERT_HEAD(head, ftmp, next); goto done; } /* If entry number is 0, find highest numbered rule and add 100 */ if (ftmp->fw_number == 0) { LIST_FOREACH(ftmp, head, next) { if (ftmp->fw_number != IPFW_DEFAULT_RULE) nbr = ftmp->fw_number; else break; } if (nbr < IPFW_DEFAULT_RULE - 100) nbr += 100; ftmp->fw_number = rule->fw_number = nbr; } /* Got a valid number; now insert it, keeping the list ordered */ fcpl = NULL ; LIST_FOREACH(fcp, head, next) { if (fcp->fw_number > ftmp->fw_number) { if (fcpl) { LIST_INSERT_AFTER(fcpl, ftmp, next); } else { LIST_INSERT_HEAD(head, ftmp, next); } break; } else { fcpl = fcp; } } flush_rule_ptrs(); done: static_count++; splx(s); DEB(printf("++ installed rule %d, static count now %d\n", ftmp->fw_number, static_count);) return (0); } /** * free storage associated with a static chain entry (including * dependent dynamic rules), and zeroes rule pointers to avoid * dangling pointer dereferences. * @return a pointer to the next entry. * Must be called at splnet() and with a non-null argument. */ static struct ip_fw * free_chain(struct ip_fw *fcp) { struct ip_fw *n; n = LIST_NEXT(fcp, next); DELETE_DYN_CHAIN(fcp); LIST_REMOVE(fcp, next); static_count--; #ifdef DUMMYNET dn_rule_delete(fcp) ; #endif flush_rule_ptrs(); /* more efficient to do outside the loop */ free(fcp, M_IPFW); return n; } /** * remove all rules with given number. */ static int del_entry(struct ip_fw_head *chainptr, u_short number) { struct ip_fw *rule; if (number != IPFW_DEFAULT_RULE) { LIST_FOREACH(rule, chainptr, next) { if (rule->fw_number == number) { int s ; s = splnet(); /* prevent access to rules while removing */ while (rule && rule->fw_number == number) rule = free_chain(rule); /* XXX could move flush_rule_ptrs() here */ splx(s); return 0 ; } } } return (EINVAL); } /** * Reset some or all counters on firewall rules. * @arg frwl is null to clear all entries, or contains a specific * rule number. * @arg log_only is 1 if we only want to reset logs, zero otherwise. */ static int zero_entry(struct ip_fw *frwl, int log_only) { struct ip_fw *rule; int s; u_short number = 0 ; char *msg ; if (frwl == 0) { s = splnet(); LIST_FOREACH(rule, &ip_fw_chain_head, next) { if (log_only == 0) { rule->fw_bcnt = rule->fw_pcnt = 0; rule->timestamp = 0; } rule->fw_loghighest = rule->fw_pcnt+rule->fw_logamount; } splx(s); msg = log_only ? "ipfw: All logging counts cleared.\n" : "ipfw: Accounting cleared.\n"; } else { int cleared = 0; number = frwl->fw_number ; /* * 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. */ LIST_FOREACH(rule, &ip_fw_chain_head, next) if (number == rule->fw_number) { s = splnet(); while (rule && number == rule->fw_number) { if (log_only == 0) { rule->fw_bcnt = rule->fw_pcnt = 0; rule->timestamp = 0; } rule->fw_loghighest = rule->fw_pcnt+ rule->fw_logamount; rule = LIST_NEXT(rule, next); } splx(s); cleared = 1; break; } if (!cleared) /* we didn't find any matching rules */ return (EINVAL); msg = log_only ? "Entry %d logging count reset.\n" : "ipfw: Entry %d cleared.\n"; } if (fw_verbose) log(LOG_SECURITY | LOG_NOTICE, msg, number); 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); } if (frwl->fw_flg == IP_FW_F_CHECK_S) { /* check-state */ return 0 ; } /* 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 (IP_FW_HAVEPORTS(frwl)) { 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); } } if (frwl->fw_flg & (IP_FW_F_UID | IP_FW_F_GID)) { if ((frwl->fw_prot != IPPROTO_TCP) && (frwl->fw_prot != IPPROTO_UDP) && (frwl->fw_prot != IPPROTO_IP)) { dprintf(("%s cannot use uid/gid logic on non-TCP/UDP\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: /* pipe 0 is invalid */ case IP_FW_F_QUEUE: /* queue 0 is invalid */ #endif if (frwl->fw_divert_port == 0) { dprintf(("%s 0 is an invalid argument\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 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 *fcp; struct ip_fw frwl, *bp , *buf; /* * Disallow modifications in really-really secure mode, but still allow * the logging counters to be reset. */ if (sopt->sopt_name == IP_FW_ADD || (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) { error = securelevel_ge(sopt->sopt_td->td_proc->p_ucred, 3); if (error) return (error); } error = 0; switch (sopt->sopt_name) { case IP_FW_GET: s = splnet(); /* size of static rules */ size = static_count * sizeof(struct ip_fw) ; if (ipfw_dyn_v) /* add size of dyn.rules */ size += (dyn_count * sizeof(struct ipfw_dyn_rule)); /* * XXX todo: if the user passes a short length to know how * much room is needed, do not * bother filling up the buffer, just jump to the * sooptcopyout. */ buf = malloc(size, M_TEMP, M_WAITOK); if (buf == 0) { splx(s); error = ENOBUFS; break; } bp = buf ; LIST_FOREACH(fcp, &ip_fw_chain_head, next) { bcopy(fcp, bp, sizeof *fcp); bp++; } if (ipfw_dyn_v) { int i ; struct ipfw_dyn_rule *p, *dst, *last = NULL ; dst = (struct ipfw_dyn_rule *)bp ; for (i = 0 ; i < curr_dyn_buckets ; i++ ) for ( p = ipfw_dyn_v[i] ; p != NULL ; p = p->next, dst++ ) { bcopy(p, dst, sizeof *p); (int)dst->rule = p->rule->fw_number ; dst->next = dst ; /* fake non-null pointer... */ last = dst ; if (TIME_LEQ(dst->expire, time_second) ) dst->expire = 0 ; else dst->expire -= time_second ; } if (last != NULL) last->next = NULL ; } splx(s); error = sooptcopyout(sopt, buf, size); FREE(buf, M_TEMP); break; case IP_FW_FLUSH: /* * Normally we cannot release the lock on each iteration. * We could do it here only because we start from the head all * the times so there is no risk of missing some entries. * On the other hand, the risk is that we end up with * a very inconsistent ruleset, so better keep the lock * around the whole cycle. * * XXX this code can be improved by resetting the head of * the list to point to the default rule, and then freeing * the old list without the need for a lock. */ s = splnet(); while ( (fcp = LIST_FIRST(&ip_fw_chain_head)) && fcp->fw_number != IPFW_DEFAULT_RULE ) free_chain(fcp); splx(s); 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_head, &frwl); if (!error && sopt->sopt_dir == SOPT_GET) error = sooptcopyout(sopt, &frwl, sizeof 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_head, frwl.fw_number); } break; case IP_FW_ZERO: case IP_FW_RESETLOG: { int cmd = (sopt->sopt_name == IP_FW_RESETLOG ); void *arg = NULL ; if (sopt->sopt_val != 0) { error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl); if (error) break ; arg = &frwl ; } error = zero_entry(arg, cmd); } break; default: printf("ip_fw_ctl invalid option %d\n", sopt->sopt_name); error = EINVAL ; } return (error); } /** * dummynet needs a reference to the default rule, because rules can * be deleted while packets hold a reference to them (e.g. to resume * processing at the next rule). When this happens, dummynet changes * the reference to the default rule (probably it could well be a * NULL pointer, but this way we do not need to check for the special * case, plus here he have info on the default behaviour. */ struct ip_fw *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_head); 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_head, &default_rule)) panic("ip_fw_init"); ip_fw_default_rule = LIST_FIRST(&ip_fw_chain_head) ; printf("IP packet filtering initialized, " #ifdef IPDIVERT "divert enabled, " #else "divert disabled, " #endif #ifdef IPFIREWALL_FORWARD "rule-based forwarding enabled, " #else "rule-based forwarding disabled, " #endif #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT "default to accept, "); #else "default to deny, " ); #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; struct ip_fw *fcp; 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 ( (fcp = LIST_FIRST(&ip_fw_chain_head)) != NULL) free_chain(fcp); splx(s); printf("IP firewall unloaded\n"); return 0; default: break; } return 0; } static moduledata_t ipfwmod = { "ipfw", ipfw_modevent, 0 }; DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY);