/* * Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $FreeBSD$ */ #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 #include #include #include #include #include #include #include #include /* XXX for ETHERTYPE_IP */ static int fw_verbose = 0; static int verbose_limit = 0; #define IPFW_DEFAULT_RULE 65535 /* * list of rules for layer 3 */ static struct ip_fw *layer3_chain; MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); static int fw_debug = 1; int fw_one_pass = 1; static int autoinc_step = 100; /* bounded to 1..1000 in add_rule() */ #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, autoinc_step, CTLFLAG_RW, &autoinc_step, 0, "Rule number autincrement step"); 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, &verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); /* * Description of dynamic rules. * * 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, its address fields are first masked * with the mask defined for the rule, then hashed, then matched * against the entries in the corresponding list. * Dynamic rules can be used for different purposes: * + stateful rules; * + enforcing limits on the number of sessions; * + in-kernel NAT (not implemented yet) * * 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 rule 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. XXX we should make them survive. * * 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 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. * XXX not implemented yet. */ static u_int32_t dyn_grace_time = 10; static u_int32_t static_count = 0; /* # of static rules */ static u_int32_t static_len = 0; /* size in bytes 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 /* SYSCTL_NODE */ static ip_fw_chk_t ipfw_chk; ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL; /* hook into dummynet */ /* * This macro maps an ip pointer into a layer3 header pointer of type T */ #define L3HDR(T, ip) ((T *)((u_int32_t *)(ip) + (ip)->ip_hl)) static int icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd) { int type = L3HDR(struct icmp,ip)->icmp_type; return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<icmp_type; return (type <= ICMP_MAXTYPE && (TT & (1<arg1 or cmd->d[0]. * * We scan options and store the bits we find set. We succeed if * * (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear * * The code is sometimes optimized not to store additional variables. */ static int flags_match(ipfw_insn *cmd, u_int8_t bits) { u_char want_clear; bits = ~bits; if ( ((cmd->arg1 & 0xff) & bits) != 0) return 0; /* some bits we want set were clear */ want_clear = (cmd->arg1 >> 8) & 0xff; if ( (want_clear & bits) != want_clear) return 0; /* some bits we want clear were set */ return 1; } static int ipopts_match(struct ip *ip, ipfw_insn *cmd) { int optlen, bits = 0; u_char *cp = (u_char *)(ip + 1); int x = (ip->ip_hl << 2) - sizeof (struct ip); for (; x > 0; x -= optlen, cp += optlen) { int opt = cp[IPOPT_OPTVAL]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) optlen = 1; else { optlen = cp[IPOPT_OLEN]; if (optlen <= 0 || optlen > x) return 0; /* invalid or truncated */ } switch (opt) { default: break; case IPOPT_LSRR: bits |= IP_FW_IPOPT_LSRR; break; case IPOPT_SSRR: bits |= IP_FW_IPOPT_SSRR; break; case IPOPT_RR: bits |= IP_FW_IPOPT_RR; break; case IPOPT_TS: bits |= IP_FW_IPOPT_TS; break; } } return (flags_match(cmd, bits)); } static int tcpopts_match(struct ip *ip, ipfw_insn *cmd) { int optlen, bits = 0; struct tcphdr *tcp = L3HDR(struct tcphdr,ip); u_char *cp = (u_char *)(tcp + 1); int x = (tcp->th_off << 2) - sizeof(struct tcphdr); for (; x > 0; x -= optlen, cp += optlen) { int 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: bits |= IP_FW_TCPOPT_MSS; break; case TCPOPT_WINDOW: bits |= IP_FW_TCPOPT_WINDOW; break; case TCPOPT_SACK_PERMITTED: case TCPOPT_SACK: bits |= IP_FW_TCPOPT_SACK; break; case TCPOPT_TIMESTAMP: bits |= IP_FW_TCPOPT_TS; break; case TCPOPT_CC: case TCPOPT_CCNEW: case TCPOPT_CCECHO: bits |= IP_FW_TCPOPT_CC; break; } } return (flags_match(cmd, bits)); } /* * XXX done */ static int iface_match(struct ifnet *ifp, ipfw_insn_if *cmd) { if (ifp == NULL) /* no iface with this packet, match fails */ return 0; /* Check by name or by IP address */ if (cmd->name[0] != '\0') { /* XXX by name */ /* Check unit number (-1 is wildcard) */ if (cmd->p.unit != -1 && cmd->p.unit != ifp->if_unit) return(0); /* Check name */ if (!strncmp(ifp->if_name, cmd->name, IFNAMSIZ)) return(1); } else { 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 (cmd->p.ip.s_addr == ((struct sockaddr_in *) (ia->ifa_addr))->sin_addr.s_addr) return(1); /* match */ } } return(0); /* no match, fail ... */ } static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */ #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 /* * We enter here when we have a rule with O_LOG. */ static void ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh, struct mbuf *m, struct ifnet *oif) { char *action; char action2[32], proto[47], fragment[27]; int limit_reached = 0; fragment[0] = '\0'; proto[0] = '\0'; if (f == NULL) { /* bogus pkt */ if (verbose_limit != 0 && norule_counter >= verbose_limit) return; norule_counter++; if (norule_counter == verbose_limit) limit_reached = verbose_limit; action = "Refuse"; } else { /* O_LOG is the first action, find the real one */ ipfw_insn *cmd = ACTION_PTR(f); ipfw_insn_log *l = (ipfw_insn_log *)cmd; if (l->max_log != 0 && l->log_left == 0) return; l->log_left--; if (l->log_left == 0) limit_reached = l->max_log; cmd += F_LEN(cmd); /* point to first action */ if (cmd->opcode == O_PROB) cmd += F_LEN(cmd); action = action2; switch (cmd->opcode) { case O_DENY: action = "Deny"; break; case O_REJECT: action = (cmd->arg1==ICMP_REJECT_RST) ? "Reset" : "Unreach"; break; case O_ACCEPT: action = "Accept"; break; case O_COUNT: action = "Count"; break; case O_DIVERT: snprintf(SNPARGS(action2, 0), "Divert %d", cmd->arg1); break; case O_TEE: snprintf(SNPARGS(action2, 0), "Tee %d", cmd->arg1); break; case O_SKIPTO: snprintf(SNPARGS(action2, 0), "SkipTo %d", cmd->arg1); break; case O_PIPE: snprintf(SNPARGS(action2, 0), "Pipe %d", cmd->arg1); break; case O_QUEUE: snprintf(SNPARGS(action2, 0), "Queue %d", cmd->arg1); break; case O_FORWARD_IP: { ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd; if (sa->sa.sin_port) snprintf(SNPARGS(action2, 0), "Forward to %s:%d", inet_ntoa(sa->sa.sin_addr), sa->sa.sin_port); else snprintf(SNPARGS(action2, 0), "Forward to %s", inet_ntoa(sa->sa.sin_addr)); } break; default: action = "UNKNOWN"; break; } } if (hlen == 0) { /* non-ip */ snprintf(SNPARGS(proto, 0), "MAC"); } else { struct ip *ip = mtod(m, struct ip *); /* these three are all aliases to the same thing */ struct icmp *const icmp = L3HDR(struct icmp, ip); struct tcphdr *const tcp = (struct tcphdr *)icmp; struct udphdr *const udp = (struct udphdr *)icmp; int ip_off, offset, ip_len; int len; if (eh != NULL) { /* layer 2 packets are as on the wire */ ip_off = ntohs(ip->ip_off); ip_len = ntohs(ip->ip_len); } else { ip_off = ip->ip_off; ip_len = ip->ip_len; } offset = ip_off & IP_OFFMASK; 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_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_off & IP_MF) ? "+" : ""); } if (oif || m->m_pkthdr.rcvif) log(LOG_SECURITY | LOG_INFO, "ipfw: %d %s %s %s via %s%d%s\n", f ? f->rulenum : -1, action, proto, oif ? "out" : "in", oif ? oif->if_name : m->m_pkthdr.rcvif->if_name, oif ? oif->if_unit : m->m_pkthdr.rcvif->if_unit, fragment); else log(LOG_SECURITY | LOG_INFO, "ipfw: %d %s %s [no if info]%s\n", f ? f->rulenum : -1, action, proto, fragment); if (limit_reached) log(LOG_SECURITY | LOG_NOTICE, "ipfw: limit %d reached on entry %d\n", limit_reached, f ? f->rulenum : -1); } /* * IMPORTANT: the hash function for dynamic rules must be commutative * in * source and destination (ip,port), because rules are bidirectional * and we want to find both in the same bucket. */ 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) { \ ipfw_dyn_rule *old_q = q; \ \ /* remove a refcount to the parent */ \ if (q->dyn_type == O_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 \ head = q = q->next; \ dyn_count--; \ free(old_q, M_IPFW); } #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) /** * Remove dynamic rules pointing to "rule", or all of them if rule == NULL. * * If keep_me == NULL, rules are deleted even if not expired, * otherwise only expired rules are removed. * * The value of the second parameter is also used to point to identify * a rule we absolutely do not want to remove (e.g. because we are * holding a reference to it -- this is the case with O_LIMIT_PARENT * rules). The pointer is only used for comparison, so any non-null * value will do. */ static void remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me) { static u_int32_t last_remove = 0; #define FORCE (keep_me == NULL) ipfw_dyn_rule *prev, *q; int i, pass = 0, max_pass = 0; if (ipfw_dyn_v == NULL || dyn_count == 0) return; /* do not expire more than once per second, it is useless */ if (!FORCE && last_remove == time_second) return; last_remove = time_second; /* * because O_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. */ next_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. */ if (q == keep_me) goto next; if (rule != NULL && rule != q->rule) goto next; /* not the one we are looking for */ if (q->dyn_type == O_LIMIT_PARENT) { /* * handle parent in the second pass, * record we need one. */ max_pass = 1; if (pass == 0) goto next; if (FORCE && q->count != 0 ) { /* XXX should not happen! */ printf( "OUCH! cannot remove rule," " count %d\n", q->count); } } else { if (!FORCE && !TIME_LEQ( q->expire, time_second )) goto next; } UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q); continue; next: prev=q; q=q->next; } } if (pass++ < max_pass) goto next_pass; } /** * lookup a dynamic rule. */ static ipfw_dyn_rule * lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction) { /* * stateful ipfw extensions. * Lookup into dynamic session queue */ #define MATCH_REVERSE 0 #define MATCH_FORWARD 1 #define MATCH_NONE 2 #define MATCH_UNKNOWN 3 int i, dir = MATCH_NONE; ipfw_dyn_rule *prev, *q=NULL; if (ipfw_dyn_v == NULL) goto done; /* not found */ i = hash_packet( pkt ); for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { if (q->dyn_type == O_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; break; } 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 = MATCH_REVERSE; break; } } next: prev = q; q = q->next; } if (q == NULL) goto done; /* q = NULL, not 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); #define BOTH_SYN (TH_SYN | (TH_SYN << 8)) #define BOTH_FIN (TH_FIN | (TH_FIN << 8)) q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); switch (q->state) { case TH_SYN: /* opening */ q->expire = time_second + dyn_syn_lifetime; break; case BOTH_SYN: /* move to established */ q->expire = time_second + dyn_ack_lifetime; break; case BOTH_SYN | TH_FIN : /* one side tries to close */ case BOTH_SYN | (TH_FIN << 8) : q->expire = time_second + dyn_ack_lifetime; break; case BOTH_SYN | BOTH_FIN: /* 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; } done: if (match_direction) *match_direction = dir; return q; } static void realloc_dynamic_table(void) { /* try reallocation, make sure we have a power of 2 */ if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */ dyn_buckets = curr_dyn_buckets; /* reset */ return; } curr_dyn_buckets = dyn_buckets; if (ipfw_dyn_v != NULL) free(ipfw_dyn_v, M_IPFW); ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *), M_IPFW, M_DONTWAIT | M_ZERO); } /** * Install state of type 'type' for a dynamic session. * The hash table contains two type of rules: * - regular rules (O_KEEP_STATE) * - rules for sessions with limited number of sess per user * (O_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 (O_LIMIT_PARENT). */ static ipfw_dyn_rule * add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule) { ipfw_dyn_rule *r; int i; if (ipfw_dyn_v == NULL || (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { realloc_dynamic_table(); 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 == O_LIMIT) { ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; if ( parent->dyn_type != O_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 dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n", dyn_type, (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 rule as search keys. * If the lookup fails, then install one. */ static ipfw_dyn_rule * lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule) { 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 == O_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, O_LIMIT_PARENT, rule); } /** * Install dynamic state for rule type cmd->o.opcode * * 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, ipfw_insn_limit *cmd, struct ip_fw_args *args) { static int last_log; ipfw_dyn_rule *q; DEB(printf("-- install state type %d 0x%08x %u -> 0x%08x %u\n", cmd->o.opcode, (args->f_id.src_ip), (args->f_id.src_port), (args->f_id.dst_ip), (args->f_id.dst_port) );) q = lookup_dyn_rule(&args->f_id, NULL); if (q != NULL) { /* should never occur */ if (last_log != time_second) { last_log = time_second; printf(" install_state: entry already present, done\n"); } return 0; } if (dyn_count >= dyn_max) /* * Run out of slots, try to remove any expired rule. */ remove_dyn_rule(NULL, (ipfw_dyn_rule *)1); if (dyn_count >= dyn_max) { if (last_log != time_second) { last_log = time_second; printf("install_state: Too many dynamic rules\n"); } return 1; /* cannot install, notify caller */ } switch (cmd->o.opcode) { case O_KEEP_STATE: /* bidir rule */ add_dyn_rule(&args->f_id, O_KEEP_STATE, rule); break; case O_LIMIT: /* limit number of sessions */ { u_int16_t limit_mask = cmd->limit_mask; struct ipfw_flow_id id; ipfw_dyn_rule *parent; DEB(printf("installing dyn-limit rule %d\n", cmd->conn_limit);) id.dst_ip = id.src_ip = 0; id.dst_port = id.src_port = 0; id.proto = args->f_id.proto; if (limit_mask & DYN_SRC_ADDR) id.src_ip = args->f_id.src_ip; if (limit_mask & DYN_DST_ADDR) id.dst_ip = args->f_id.dst_ip; if (limit_mask & DYN_SRC_PORT) id.src_port = args->f_id.src_port; if (limit_mask & DYN_DST_PORT) id.dst_port = args->f_id.dst_port; parent = lookup_dyn_parent(&id, rule); if (parent == NULL) { printf("add parent failed\n"); return 1; } if (parent->count >= cmd->conn_limit) { /* * See if we can remove some expired rule. */ remove_dyn_rule(rule, parent); if (parent->count >= cmd->conn_limit) { if (fw_verbose && last_log != time_second) { last_log = time_second; printf( "drop session, too many entries\n"); } return 1; } } add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); } break; default: printf("unknown dynamic rule type %u\n", cmd->o.opcode); return 1; } lookup_dyn_rule(&args->f_id, NULL); /* XXX just set the lifetime */ return 0; } /* * sends a reject message, consuming the mbuf passed as an argument. */ static void send_reject(struct mbuf *m, int code, int offset, int ip_len) { if (code != ICMP_REJECT_RST) /* Send an ICMP unreach */ icmp_error(m, ICMP_UNREACH, code, 0L, 0); else { /* XXX warning, this code writes into the mbuf */ struct ip *ip = mtod(m, struct ip *); struct tcphdr *const tcp = L3HDR(struct tcphdr, ip); struct tcpiphdr ti, *const tip = (struct tcpiphdr *) ip; int hlen = ip->ip_hl << 2; if (offset != 0 || (tcp->th_flags & TH_RST)) { m_freem(m); /* free the mbuf */ return; } ti.ti_i = *((struct ipovly *) ip); ti.ti_t = *tcp; bcopy(&ti, ip, sizeof(ti)); tip->ti_seq = ntohl(tip->ti_seq); tip->ti_ack = 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, 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, 0, TH_RST|TH_ACK); } } } /** * * Given an ip_fw *, lookup_next_rule will return a pointer * to the next rule, which can be either the jump * target (for skipto instructions) or the next one in the list (in * all other cases including a missing jump target). * The result is also written in the "next_rule" field of the rule. * Backward jumps are not allowed, so start looking from the next * rule... * * This never returns NULL -- in case we do not have an exact match, * the next rule is returned. When the ruleset is changed, * pointers are flushed so we are always correct. */ static struct ip_fw * lookup_next_rule(struct ip_fw *me) { struct ip_fw *rule = NULL; ipfw_insn *cmd; /* look for action, in case it is a skipto */ cmd = ACTION_PTR(me); if ( cmd->opcode == O_SKIPTO ) for (rule = me->next; rule ; rule = rule->next) if (rule->rulenum >= cmd->arg1) break; if (rule == NULL) /* failure or not a skipto */ rule = me->next; me->next_rule = rule; return rule; } /* * The main check routine for the firewall. * * All arguments are in args so we can modify them and return them * back to the caller. * * Parameters: * * args->m (in/out) The packet; we set to NULL when/if we nuke it. * Starts with the IP header. * args->eh (in) Mac header if present, or NULL for layer3 packet. * args->oif Outgoing interface, or NULL if packet is incoming. * The incoming interface is in the mbuf. (in) * args->divert_rule (in/out) * Skip up to the first rule past this rule number; * upon return, non-zero port number for divert or tee. * * args->rule Pointer to the last matching rule (in/out) * args->next_hop Socket we are forwarding to (out). * args->f_id Addresses grabbed from the packet (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 ipfw_chk(struct ip_fw_args *args) { /* * Local variables hold state during the processing of a packet. * * IMPORTANT NOTE: to speed up the processing of rules, there * are some assumption on the values of the variables, which * are documented here. Should you change them, please check * the implementation of the various instructions to make sure * that they still work. */ /* * args->eh The MAC header. It is non-null for a layer2 * packet, it is NULL for a layer-3 packet. * * m | args->m Pointer to the mbuf, as received from the caller. * It may change if ipfw_chk() does an m_pullup, or if it * consumes the packet because it calls send_reject(). * XXX This has to change, so that ipfw_chk() never modifies * or consumes the buffer. * ip is simply an alias of the value of m, and it is kept * in sync with it (the packet is supposed to start with * the ip header). */ struct mbuf *m = args->m; struct ip *ip = mtod(m, struct ip *); /* * oif | args->oif If NULL, ipfw_chk has been called on the * inbound path (ether_input, bdg_forward, ip_input). * If non-NULL, ipfw_chk has been called on the outbound path * (ether_output, ip_output). */ struct ifnet *oif = args->oif; struct ip_fw *f = NULL; /* matching rule */ int retval = 0; /* * hlen The length of the IPv4 header. * hlen >0 means we have an IPv4 packet. */ u_int hlen = 0; /* hlen >0 means we have an IP pkt */ /* * offset The offset of a fragment. offset != 0 means that * we have a fragment at this offset of an IPv4 packet. * offset == 0 means that (if this is an IPv4 packet) * this is the first or only fragment. */ u_short offset = 0; /* * Local copies of addresses. They are only valid if we have * an IP packet. * * proto The protocol. Set to 0 for non-ip packets, * or to the protocol read from the packet otherwise. * proto != 0 means that we have an IPv4 packet. * * src_port, dst_port port numbers, in HOST format. Only * valid for TCP and UDP packets. * * src_ip, dst_ip ip addresses, in NETWORK format. * Only valid for IPv4 packets. */ u_int8_t proto; u_int16_t src_port = 0, dst_port = 0; /* NOTE: host format */ struct in_addr src_ip, dst_ip; /* NOTE: network format */ u_int16_t ip_len=0; int dyn_dir = MATCH_UNKNOWN; ipfw_dyn_rule *q = NULL; /* * dyn_dir = MATCH_UNKNOWN when rules unchecked, * MATCH_NONE when checked and not matched (q = NULL), * MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL) */ if (args->eh == NULL || /* layer 3 packet */ ( m->m_pkthdr.len >= sizeof(struct ip) && ntohs(args->eh->ether_type) == ETHERTYPE_IP)) hlen = ip->ip_hl << 2; /* * Collect parameters into local variables for faster matching. */ if (hlen == 0) { /* do not grab addresses for non-ip pkts */ proto = args->f_id.proto = 0; /* mark f_id invalid */ goto after_ip_checks; } proto = args->f_id.proto = ip->ip_p; src_ip = ip->ip_src; dst_ip = ip->ip_dst; if (args->eh != NULL) { /* layer 2 packets are as on the wire */ 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; } #define PULLUP_TO(len) \ do { \ if ((m)->m_len < (len)) { \ args->m = m = m_pullup(m, (len)); \ if (m == 0) \ goto pullup_failed; \ ip = mtod(m, struct ip *); \ } \ } while (0) if (offset == 0) { switch (proto) { case IPPROTO_TCP: { struct tcphdr *tcp; PULLUP_TO(hlen + sizeof(struct tcphdr)); tcp = L3HDR(struct tcphdr, ip); dst_port = tcp->th_dport; src_port = tcp->th_sport; args->f_id.flags = tcp->th_flags; } break; case IPPROTO_UDP: { struct udphdr *udp; PULLUP_TO(hlen + sizeof(struct udphdr)); udp = L3HDR(struct udphdr, ip); dst_port = udp->uh_dport; src_port = udp->uh_sport; } break; case IPPROTO_ICMP: PULLUP_TO(hlen + 4); /* type, code and checksum. */ args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type; break; default: break; } #undef PULLUP_TO } args->f_id.src_ip = ntohl(src_ip.s_addr); args->f_id.dst_ip = ntohl(dst_ip.s_addr); args->f_id.src_port = src_port = ntohs(src_port); args->f_id.dst_port = dst_port = ntohs(dst_port); after_ip_checks: if (args->rule) { /* * Packet has already been tagged. Look for the next rule * to restart processing. * * If fw_one_pass != 0 then just accept it. * XXX should not happen here, but optimized out in * the caller. */ if (fw_one_pass) return 0; f = args->rule->next_rule; if (f == NULL) f = lookup_next_rule(args->rule); } else { /* * Find the starting rule. It can be either the first * one, or the one after divert_rule if asked so. */ int skipto = args->divert_rule; f = layer3_chain; if (args->eh == NULL && skipto != 0) { if (skipto >= IPFW_DEFAULT_RULE) return(IP_FW_PORT_DENY_FLAG); /* invalid */ while (f && f->rulenum <= skipto) f = f->next; if (f == NULL) /* drop packet */ return(IP_FW_PORT_DENY_FLAG); } } args->divert_rule = 0; /* reset to avoid confusion later */ /* * Now scan the rules, and parse microinstructions for each rule. */ for (; f; f = f->next) { int l, cmdlen; ipfw_insn *cmd; int skip_or; /* skip rest of OR block */ again: skip_or = 0; for (l = f->cmd_len, cmd = f->cmd ; l > 0 ; l -= cmdlen, cmd += cmdlen) { /* * check_body is a jump target used when we find a * CHECK_STATE, and need to jump to the body of * the target rule. */ check_body: cmdlen = F_LEN(cmd); /* * An OR block (insn_1 || .. || insn_n) has the * F_OR bit set in all but the last instruction. * The first match will set "skip_or", and cause * the following instructions to be skipped until * past the one with the F_OR bit clear. */ if (skip_or) { /* skip this instruction */ if ((cmd->len & F_OR) == 0) skip_or = 0; /* next one is good */ continue; } switch (cmd->opcode) { case O_NOP: goto cmd_match; /* That's easy */ case O_IPPRE: case O_FORWARD_MAC: printf("ipfw: opcode %d unimplemented\n", cmd->opcode); goto cmd_fail; case O_GID: case O_UID: /* * We only check offset == 0 && proto != 0, * as this ensures that we have an IPv4 * packet with the ports info. */ if (offset!=0) goto cmd_fail; { struct inpcbinfo *pi; int wildcard; struct inpcb *pcb; if (proto == IPPROTO_TCP) { wildcard = 0; pi = &tcbinfo; } else if (proto == IPPROTO_UDP) { wildcard = 1; pi = &udbinfo; } else goto cmd_fail; pcb = (oif) ? in_pcblookup_hash(pi, dst_ip, htons(dst_port), src_ip, htons(src_port), wildcard, oif) : in_pcblookup_hash(pi, src_ip, htons(src_port), dst_ip, htons(dst_port), wildcard, NULL); if (pcb == NULL || pcb->inp_socket == NULL) goto cmd_fail; if (cmd->opcode == O_UID) { #if __FreeBSD_version >= 500034 if (socheckuid(pcb->inp_socket, (uid_t)((ipfw_insn_u32 *)cmd)->d[0] )) #else if (pcb->inp_socket->so_cred->cr_uid != (uid_t)((ipfw_insn_u32 *)cmd)->d[0]) #endif goto cmd_match; } else { if (groupmember( (uid_t)((ipfw_insn_u32 *)cmd)->d[0], pcb->inp_socket->so_cred)) goto cmd_match; } } goto cmd_fail; case O_RECV: if (iface_match(m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd)) goto cmd_match; goto cmd_fail; case O_XMIT: if (iface_match(oif, (ipfw_insn_if *)cmd)) goto cmd_match; goto cmd_fail; case O_VIA: if (iface_match(oif ? oif : m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd)) goto cmd_match; goto cmd_fail; case O_MACADDR2: if (args->eh != NULL) { /* have MAC header */ u_int32_t *want = (u_int32_t *) ((ipfw_insn_mac *)cmd)->addr; u_int32_t *mask = (u_int32_t *) ((ipfw_insn_mac *)cmd)->mask; u_int32_t *hdr = (u_int32_t *)args->eh; if ( want[0] == (hdr[0] & mask[0]) && want[1] == (hdr[1] & mask[1]) && want[2] == (hdr[2] & mask[2]) ) goto cmd_match; } goto cmd_fail; case O_MAC_TYPE: if (args->eh != NULL) { u_int16_t type = ntohs(args->eh->ether_type); u_int16_t *p = ((ipfw_insn_u16 *)cmd)->ports; int i; for (i = cmdlen - 1; i>0; i--) if (type>=p[0] && type<=p[1]) goto cmd_match; else p += 2; } goto cmd_fail; case O_FRAG: /* XXX check this -- MF bit ? */ if (hlen == 0 || offset != 0) goto cmd_fail; goto cmd_match; case O_IN: /* "out" is "not in" */ if (oif != NULL) goto cmd_fail; goto cmd_match; case O_LAYER2: if (args->eh == NULL) goto cmd_fail; goto cmd_match; case O_PROTO: /* * We do not allow an arg of 0 so the * check of "proto" only suffices. */ if (proto == cmd->arg1) goto cmd_match; goto cmd_fail; case O_IP_SRC: if (hlen > 0 && ((ipfw_insn_ip *)cmd)->addr.s_addr == src_ip.s_addr) goto cmd_match; goto cmd_fail; case O_IP_SRC_MASK: if (hlen > 0 && ((ipfw_insn_ip *)cmd)->addr.s_addr == (src_ip.s_addr & ((ipfw_insn_ip *)cmd)->mask.s_addr)) goto cmd_match; goto cmd_fail; case O_IP_SRC_ME: if (hlen == 0) goto cmd_fail; { struct ifnet *tif; INADDR_TO_IFP(src_ip, tif); if (tif != NULL) goto cmd_match; } goto cmd_fail; case O_IP_DST_SET: case O_IP_SRC_SET: if (hlen == 0) goto cmd_fail; { u_int32_t *d = (u_int32_t *)(cmd+1); u_int32_t a = cmd->opcode == O_IP_DST_SET ? args->f_id.src_ip : args->f_id.dst_ip; if (a < d[0]) goto cmd_fail; a -= d[0]; if (a >= cmd->arg1) goto cmd_fail; if (d[ 1 + (a>>5)] & (1<<(a & 0x1f)) ) goto cmd_match; } goto cmd_fail; case O_IP_DST: if (hlen > 0 && ((ipfw_insn_ip *)cmd)->addr.s_addr == dst_ip.s_addr) goto cmd_match; goto cmd_fail; case O_IP_DST_MASK: if (hlen == 0) goto cmd_fail; if (((ipfw_insn_ip *)cmd)->addr.s_addr == (dst_ip.s_addr & ((ipfw_insn_ip *)cmd)->mask.s_addr)) goto cmd_match; goto cmd_fail; case O_IP_DST_ME: if (hlen == 0) goto cmd_fail; { struct ifnet *tif; INADDR_TO_IFP(dst_ip, tif); if (tif != NULL) goto cmd_match; } goto cmd_fail; case O_IP_SRCPORT: case O_IP_DSTPORT: /* * offset == 0 && proto != 0 is enough * to guarantee that we have an IPv4 * packet with port info. */ if (offset != 0) goto cmd_fail; if (proto==IPPROTO_UDP || proto==IPPROTO_TCP) { u_int16_t port = (cmd->opcode == O_IP_SRCPORT) ? src_port : dst_port ; u_int16_t *p = ((ipfw_insn_u16 *)cmd)->ports; int i; for (i = cmdlen - 1; i>0; i--) if (port>=p[0] && port<=p[1]) goto cmd_match; else p += 2; } goto cmd_fail; case O_ICMPTYPE: if (offset > 0 || proto != IPPROTO_ICMP || !icmptype_match(ip, (ipfw_insn_u32 *)cmd) ) goto cmd_fail; goto cmd_match; case O_IPOPT: if (hlen == 0 || !ipopts_match(ip, cmd) ) goto cmd_fail; goto cmd_match; case O_IPVER: if (hlen == 0 || cmd->arg1 != ip->ip_v) goto cmd_fail; goto cmd_match; case O_IPTTL: if (hlen == 0 || cmd->arg1 != ip->ip_ttl) goto cmd_fail; goto cmd_match; case O_IPID: if (hlen == 0 || cmd->arg1 != ntohs(ip->ip_id)) goto cmd_fail; goto cmd_match; case O_IPLEN: if (hlen == 0 || cmd->arg1 != ip_len) goto cmd_fail; goto cmd_match; case O_IPTOS: if (hlen == 0 || !flags_match(cmd, ip->ip_tos)) goto cmd_fail; goto cmd_match; case O_TCPFLAGS: if (proto != IPPROTO_TCP || offset > 0 || !flags_match(cmd, L3HDR(struct tcphdr,ip)->th_flags)) goto cmd_fail; goto cmd_match; case O_TCPOPTS: if (proto != IPPROTO_TCP || offset > 0 || !tcpopts_match(ip, cmd)) goto cmd_fail; goto cmd_match; case O_TCPSEQ: if (proto != IPPROTO_TCP || offset > 0 || ((ipfw_insn_u32 *)cmd)->d[0] != L3HDR(struct tcphdr,ip)->th_seq) goto cmd_fail; goto cmd_match; case O_TCPACK: if (proto != IPPROTO_TCP || offset > 0 || ((ipfw_insn_u32 *)cmd)->d[0] != L3HDR(struct tcphdr,ip)->th_ack) goto cmd_fail; goto cmd_match; case O_TCPWIN: if (proto != IPPROTO_TCP || offset > 0 || cmd->arg1 != L3HDR(struct tcphdr,ip)->th_win) goto cmd_fail; goto cmd_match; case O_ESTAB: if (proto != IPPROTO_TCP || offset > 0) goto cmd_fail; /* reject packets which have SYN only */ if ((L3HDR(struct tcphdr,ip)->th_flags & (TH_RST | TH_ACK | TH_SYN)) == TH_SYN) goto cmd_fail; goto cmd_match; case O_LOG: ipfw_log(f, hlen, args->eh, m, oif); goto cmd_match; case O_PROB: /* XXX check */ if (random() < ((ipfw_insn_u32 *)cmd)->d[0] ) goto cmd_match; goto cmd_fail; case O_LIMIT: case O_KEEP_STATE: if (install_state(f, (ipfw_insn_limit *)cmd, args)) goto deny; /* error/limit violation */ goto cmd_match; case O_PROBE_STATE: case O_CHECK_STATE: /* * dynamic rules are checked at the first * keep-state or check-state occurrence. * The compiler introduces a probe-state * instruction for us when we have a * keep-state (because probe-state needs * to be run first). */ if (dyn_dir == MATCH_UNKNOWN) { q = lookup_dyn_rule(&args->f_id, &dyn_dir); if (q != NULL) { f = q->rule; q->pcnt++; q->bcnt += ip_len; /* go to ACTION */ cmd = ACTION_PTR(f); l = f->cmd_len - f->act_ofs; goto check_body; } } if (cmd->opcode == O_CHECK_STATE) goto next_rule; else goto cmd_match; case O_ACCEPT: retval = 0; /* accept */ goto accept; case O_PIPE: case O_QUEUE: args->rule = f; /* report matching rule */ retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG; goto accept; case O_DIVERT: case O_TEE: if (args->eh) /* not on layer 2 */ goto cmd_fail; args->divert_rule = f->rulenum; if (cmd->opcode == O_DIVERT) retval = cmd->arg1; else retval = cmd->arg1|IP_FW_PORT_TEE_FLAG; goto accept; case O_COUNT: case O_SKIPTO: f->pcnt++; /* update stats */ f->bcnt += ip_len; f->timestamp = time_second; if (cmd->opcode == O_COUNT) goto next_rule; /* handle skipto */ if (f->next_rule == NULL) lookup_next_rule(f); f = f->next_rule; goto again; case O_REJECT: /* * Drop the packet and send a reject notice * if the packet is not ICMP (or is an ICMP * query), and it is not multicast/broadcast. */ if (hlen > 0 && (proto != IPPROTO_ICMP || is_icmp_query(ip)) && !(m->m_flags & (M_BCAST|M_MCAST)) && !IN_MULTICAST(dst_ip.s_addr)) { send_reject(m,cmd->arg1,offset,ip_len); args->m = m = NULL; } goto deny; case O_FORWARD_IP: if (args->eh) /* not valid on layer2 pkts */ goto cmd_fail; if (!q || dyn_dir == MATCH_FORWARD) args->next_hop = &((ipfw_insn_sa *)cmd)->sa; retval = 0; goto accept; case O_DENY: goto deny; default: panic("-- unknown opcode %d\n", cmd->opcode); } panic("ipfw_chk: end of inner loop"); /* * This code is a bit spaghetti, but we have * 4 cases to handle: * INSN FAIL, no F_NOT --> insn_fail * INSN FAIL, but we have F_NOT --> cmd_success * INSN MATCH, no F_NOT --> cmd_success * INSN MATCH, but we have F_NOT --> insn_fail * * after this: * cmd_success, F_OR --> set skip_or * cmd_success, not F_OR --> try next insn * insn_fail, F_OR --> try next insn * insn_fail, not F_OR --> rule does not match */ cmd_fail: if (cmd->len & F_NOT) /* NOT fail is a success */ goto cmd_success; else goto insn_fail; cmd_match: if (cmd->len & F_NOT) { /* NOT match is a failure. */ insn_fail: if (cmd->len & F_OR) /* If an or block */ continue; /* try next insn */ else break; /* otherwise next rule */ } cmd_success: if (cmd->len & F_OR) skip_or = 1; } /* end of inner for, scan opcodes */ next_rule:; /* try next rule */ } /* end of outer for, scan rules */ deny: retval = IP_FW_PORT_DENY_FLAG; accept: /* Update statistics */ f->pcnt++; f->bcnt += ip_len; f->timestamp = time_second; return retval; pullup_failed: if (fw_verbose) printf("pullup failed\n"); return(IP_FW_PORT_DENY_FLAG); } #if 0 /* XXX old instructions not implemented yet XXX */ bogusfrag: if (fw_verbose) { if (*m != NULL) ipfw_report(NULL, ip, ip_off, ip_len, (*m)->m_pkthdr.rcvif, oif); } return(IP_FW_PORT_DENY_FLAG); if (f->fw_ipflg & IP_FW_IF_IPPRE && (f->fw_iptos & 0xe0) != (ip->ip_tos & 0xe0)) continue; #endif /* XXX old instructions not implemented yet */ /* * When a rule is added/deleted, clear the next_rule pointers in all rules. * These will be reconstructed on the fly as packets are matched. * Must be called at splimp(). */ static void flush_rule_ptrs(void) { struct ip_fw *rule; for (rule = layer3_chain; rule; rule = rule->next) rule->next_rule = NULL; } /* * When pipes/queues are deleted, clear the "pipe_ptr" pointer to a given * pipe/queue, or to all of them (match == NULL). * Must be called at splimp(). */ void flush_pipe_ptrs(struct dn_flow_set *match) { struct ip_fw *rule; for (rule = layer3_chain; rule; rule = rule->next) { ipfw_insn_pipe *cmd = (ipfw_insn_pipe *)ACTION_PTR(rule); if (cmd->o.opcode != O_PIPE && cmd->o.opcode != O_QUEUE) continue; if (match == NULL || cmd->pipe_ptr == match) cmd->pipe_ptr = NULL; } } /* * Add a new rule to the list. Copy the rule into a malloc'ed area, then * possibly create a rule number and add the rule to the list. * Update the rule_number in the input struct so the caller knows it as well. */ static int add_rule(struct ip_fw **head, struct ip_fw *input_rule) { struct ip_fw *rule, *f, *prev; int s; int l = RULESIZE(input_rule); if (*head == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE) return (EINVAL); rule = malloc(l, M_IPFW, M_DONTWAIT | M_ZERO); if (rule == NULL) return (ENOSPC); bcopy(input_rule, rule, l); rule->next = NULL; rule->next_rule = NULL; rule->pcnt = 0; rule->bcnt = 0; rule->timestamp = 0; s = splimp(); if (*head == NULL) { /* default rule */ *head = rule; goto done; } /* * If rulenum is 0, find highest numbered rule before the * default rule, and add autoinc_step */ if (autoinc_step < 1) autoinc_step = 1; else if (autoinc_step > 1000) autoinc_step = 1000; if (rule->rulenum == 0) { /* * locate the highest numbered rule before default */ for (f = *head; f; f = f->next) { if (f->rulenum == IPFW_DEFAULT_RULE) break; rule->rulenum = f->rulenum; } if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step) rule->rulenum += autoinc_step; input_rule->rulenum = rule->rulenum; } /* * Now insert the new rule in the right place in the sorted list. */ for (prev = NULL, f = *head; f; prev = f, f = f->next) { if (f->rulenum > rule->rulenum) { /* found the location */ if (prev) { rule->next = f; prev->next = rule; } else { /* head insert */ rule->next = *head; *head = rule; } break; } } flush_rule_ptrs(); done: static_count++; static_len += l; splx(s); DEB(printf("++ installed rule %d, static count now %d\n", rule->rulenum, static_count);) return (0); } /** * Free storage associated with a static rule (including derived * dynamic rules). * The caller is in charge of clearing rule pointers to avoid * dangling pointers. * @return a pointer to the next entry. * Arguments are not checked, so they better be correct. * Must be called at splimp(). */ static struct ip_fw * delete_rule(struct ip_fw **head, struct ip_fw *prev, struct ip_fw *rule) { struct ip_fw *n; int l = RULESIZE(rule); n = rule->next; remove_dyn_rule(rule, NULL /* force removal */); if (prev == NULL) *head = n; else prev->next = n; static_count--; static_len -= l; if (DUMMYNET_LOADED) ip_dn_ruledel_ptr(rule); free(rule, M_IPFW); return n; } /* * Deletes all rules from a chain (including the default rule * if the second argument is set). * Must be called at splimp(). */ static void free_chain(struct ip_fw **chain, int kill_default) { struct ip_fw *rule; flush_rule_ptrs(); /* more efficient to do outside the loop */ while ( (rule = *chain) != NULL && (kill_default || rule->rulenum != IPFW_DEFAULT_RULE) ) delete_rule(chain, NULL, rule); } /** * Remove all rules with given number. */ static int del_entry(struct ip_fw **chain, u_short rulenum) { struct ip_fw *prev, *rule; int s; if (rulenum == IPFW_DEFAULT_RULE) return EINVAL; /* * locate first rule to delete */ for (prev = NULL, rule = *chain; rule && rule->rulenum < rulenum; prev = rule, rule = rule->next) ; if (rule->rulenum != rulenum) return EINVAL; s = splimp(); /* no access to rules while removing */ flush_rule_ptrs(); /* more efficient to do outside the loop */ /* * prev remains the same throughout the cycle */ while (rule && rule->rulenum == rulenum) rule = delete_rule(chain, prev, rule); splx(s); return 0; } /* * Clear counters for a specific rule. */ static void clear_counters(struct ip_fw *rule, int log_only) { ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule); if (log_only == 0) { rule->bcnt = rule->pcnt = 0; rule->timestamp = 0; } if (l->o.opcode == O_LOG) l->log_left = l->max_log; } /** * 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(int rulenum, int log_only) { struct ip_fw *rule; int s; char *msg; if (rulenum == 0) { s = splimp(); norule_counter = 0; for (rule = layer3_chain; rule; rule = rule->next) clear_counters(rule, log_only); splx(s); msg = log_only ? "ipfw: All logging counts reset.\n" : "ipfw: Accounting cleared.\n"; } else { int cleared = 0; /* * We can have multiple rules with the same number, so we * need to clear them all. */ for (rule = layer3_chain; rule; rule = rule->next) if (rule->rulenum == rulenum) { s = splimp(); while (rule && rule->rulenum == rulenum) { clear_counters(rule, log_only); rule = rule->next; } splx(s); cleared = 1; break; } if (!cleared) /* we did not find any matching rules */ return (EINVAL); msg = log_only ? "ipfw: Entry %d logging count reset.\n" : "ipfw: Entry %d cleared.\n"; } if (fw_verbose) log(LOG_SECURITY | LOG_NOTICE, msg, rulenum); return (0); } /* * Check validity of the structure before insert. * Fortunately rules are simple, so this mostly need to check rule sizes. */ static int check_ipfw_struct(struct ip_fw *rule, int size) { int l, cmdlen = 0; int have_action=0; ipfw_insn *cmd; if (size < sizeof(*rule)) { printf("kipfw: rule too short\n"); return (EINVAL); } /* first, check for valid size */ l = RULESIZE(rule); if (l != size) { printf("kipfw: size mismatch (have %d want %d)\n", size, l); return (EINVAL); } /* * Now go for the individual checks. Very simple ones, basically only * instruction sizes. */ for (l = rule->cmd_len, cmd = rule->cmd ; l > 0 ; l -= cmdlen, cmd += cmdlen) { cmdlen = F_LEN(cmd); if (cmdlen > l) { printf("kipfw: opcode %d size truncated\n", cmd->opcode); return EINVAL; } DEB(printf("kipfw: opcode %d\n", cmd->opcode);) switch (cmd->opcode) { case O_NOP: case O_PROBE_STATE: case O_KEEP_STATE: case O_PROTO: case O_IP_SRC_ME: case O_IP_DST_ME: case O_LAYER2: case O_IN: case O_FRAG: case O_IPOPT: case O_IPLEN: case O_IPID: case O_IPPRE: case O_IPTOS: case O_IPTTL: case O_IPVER: case O_TCPWIN: case O_TCPFLAGS: case O_TCPOPTS: case O_ESTAB: if (cmdlen != F_INSN_SIZE(ipfw_insn)) goto bad_size; break; case O_UID: case O_GID: case O_IP_SRC: case O_IP_DST: case O_TCPSEQ: case O_TCPACK: case O_PROB: case O_ICMPTYPE: if (cmdlen != F_INSN_SIZE(ipfw_insn_u32)) goto bad_size; break; case O_LIMIT: if (cmdlen != F_INSN_SIZE(ipfw_insn_limit)) goto bad_size; break; case O_LOG: if (cmdlen != F_INSN_SIZE(ipfw_insn_log)) goto bad_size; ((ipfw_insn_log *)cmd)->log_left = ((ipfw_insn_log *)cmd)->max_log; break; case O_IP_SRC_MASK: case O_IP_DST_MASK: if (cmdlen != F_INSN_SIZE(ipfw_insn_ip)) goto bad_size; if (((ipfw_insn_ip *)cmd)->mask.s_addr == 0) { printf("kipfw: opcode %d, useless rule\n", cmd->opcode); return EINVAL; } break; case O_IP_SRC_SET: case O_IP_DST_SET: if (cmd->arg1 == 0 || cmd->arg1 > 256) { printf("kipfw: invalid set size %d\n", cmd->arg1); return EINVAL; } if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) + (cmd->arg1+31)/32 ) goto bad_size; break; case O_MACADDR2: if (cmdlen != F_INSN_SIZE(ipfw_insn_mac)) goto bad_size; break; case O_MAC_TYPE: case O_IP_SRCPORT: case O_IP_DSTPORT: /* XXX artificial limit, 15 port pairs */ if (cmdlen < 2 || cmdlen > 15) goto bad_size; break; case O_RECV: case O_XMIT: case O_VIA: if (cmdlen != F_INSN_SIZE(ipfw_insn_if)) goto bad_size; break; case O_PIPE: case O_QUEUE: if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe)) goto bad_size; goto check_action; case O_FORWARD_IP: /* XXX no! */ if (cmdlen != F_INSN_SIZE(ipfw_insn_sa)) goto bad_size; goto check_action; case O_FORWARD_MAC: /* XXX no! */ case O_CHECK_STATE: case O_COUNT: case O_ACCEPT: case O_DENY: case O_REJECT: case O_SKIPTO: case O_DIVERT: case O_TEE: if (cmdlen != F_INSN_SIZE(ipfw_insn)) goto bad_size; check_action: if (have_action) { printf("kipfw: opcode %d, multiple actions" " not allowed\n", cmd->opcode); return EINVAL; } have_action = 1; if (l != cmdlen) { printf("kipfw: opcode %d, action must be" " last opcode\n", cmd->opcode); return EINVAL; } break; default: printf("kipfw: opcode %d, unknown opcode\n", cmd->opcode); return EINVAL; } } if (have_action == 0) { printf("kipfw: missing action\n"); return EINVAL; } return 0; bad_size: printf("kipfw: opcode %d size %d wrong\n", cmd->opcode, cmdlen); return EINVAL; } /** * {set|get}sockopt parser. */ static int ipfw_ctl(struct sockopt *sopt) { int error, s, rulenum; size_t size; struct ip_fw *bp , *buf, *rule; static u_int32_t rule_buf[255]; /* we copy the data here */ /* * 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)) { #if __FreeBSD_version >= 500034 error = securelevel_ge(sopt->sopt_td->td_ucred, 3); if (error) return (error); #else /* FreeBSD 4.x */ if (securelevel >= 3) return (EPERM); #endif } error = 0; switch (sopt->sopt_name) { case IP_FW_GET: /* * pass up a copy of the current rules. Static rules * come first (the last of which has number IPFW_DEFAULT_RULE), * followed by a possibly empty list of dynamic rule. * The last dynamic rule has NULL in the "next" field. */ s = splimp(); size = static_len; /* size of static rules */ if (ipfw_dyn_v) /* add size of dyn.rules */ size += (dyn_count * sizeof(ipfw_dyn_rule)); /* * XXX todo: if the user passes a short length just 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; for (rule = layer3_chain; rule ; rule = rule->next) { int i = RULESIZE(rule); bcopy(rule, bp, i); bp = (struct ip_fw *)((char *)bp + i); } if (ipfw_dyn_v) { int i; ipfw_dyn_rule *p, *dst, *last = NULL; dst = (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->rulenum ; /* * store a non-null value in "next". * The userland code will interpret a * NULL here as a marker * for the last dynamic rule. */ dst->next = dst ; last = dst ; dst->expire = TIME_LEQ(dst->expire, time_second) ? 0 : dst->expire - time_second ; } if (last != NULL) /* mark last dynamic rule */ 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 = splimp(); free_chain(&layer3_chain, 0 /* keep default rule */); splx(s); break; case IP_FW_ADD: rule = (struct ip_fw *)rule_buf; /* XXX do a malloc */ error = sooptcopyin(sopt, rule, sizeof(rule_buf), sizeof(struct ip_fw) ); size = sopt->sopt_valsize; if (error || (error = check_ipfw_struct(rule, size))) break; error = add_rule(&layer3_chain, rule); size = RULESIZE(rule); if (!error && sopt->sopt_dir == SOPT_GET) error = sooptcopyout(sopt, rule, size); break; case IP_FW_DEL: /* argument is an int, the rule number */ error = sooptcopyin(sopt, &rulenum, sizeof(int), sizeof(int)); if (error) break; if (rulenum == IPFW_DEFAULT_RULE) { if (fw_debug) printf("ipfw: can't delete rule %u\n", (unsigned)IPFW_DEFAULT_RULE); error = EINVAL; } else error = del_entry(&layer3_chain, rulenum); break; case IP_FW_ZERO: case IP_FW_RESETLOG: /* argument is an int, the rule number */ rulenum=0; if (sopt->sopt_val != 0) { error = sooptcopyin(sopt, &rulenum, sizeof(int), sizeof(int)); if (error) break; } error = zero_entry(rulenum, sopt->sopt_name == IP_FW_RESETLOG); break; default: printf("ipfw_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. When this happens, * dummynet changes the reference to the default rule (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; static void ipfw_init(void) { struct ip_fw default_rule; ip_fw_chk_ptr = ipfw_chk; ip_fw_ctl_ptr = ipfw_ctl; layer3_chain = NULL; bzero(&default_rule, sizeof default_rule); default_rule.act_ofs = 0; default_rule.rulenum = IPFW_DEFAULT_RULE; default_rule.cmd_len = 1; default_rule.cmd[0].len = 1; default_rule.cmd[0].opcode = #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT 1 ? O_ACCEPT : #endif O_DENY; add_rule(&layer3_chain, &default_rule); ip_fw_default_rule = layer3_chain; printf("IP packet filtering initialized, divert %s, " "rule-based forwarding %s, default to %s, logging ", #ifdef IPDIVERT "enabled", #else "disabled", #endif "enabled", default_rule.cmd[0].opcode == O_ACCEPT ? "accept" : "deny"); #ifdef IPFIREWALL_VERBOSE fw_verbose = 1; #endif #ifdef IPFIREWALL_VERBOSE_LIMIT verbose_limit = IPFIREWALL_VERBOSE_LIMIT; #endif printf("logging "); if (fw_verbose == 0) printf("disabled\n"); else if (verbose_limit == 0) printf("unlimited\n"); else printf("limited to %d packets/entry by default\n", verbose_limit); } static int ipfw_modevent(module_t mod, int type, void *unused) { int s; int err = 0; switch (type) { case MOD_LOAD: s = splimp(); if (IPFW_LOADED) { splx(s); printf("IP firewall already loaded\n"); err = EEXIST; } else { ipfw_init(); splx(s); } break; case MOD_UNLOAD: #if !defined(KLD_MODULE) printf("ipfw statically compiled, cannot unload\n"); err = EBUSY; #else s = splimp(); ip_fw_chk_ptr = NULL; ip_fw_ctl_ptr = NULL; free_chain(&layer3_chain, 1 /* kill default rule */); splx(s); printf("IP firewall unloaded\n"); #endif break; default: break; } return err; } static moduledata_t ipfwmod = { "ipfw", ipfw_modevent, 0 }; DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY); MODULE_VERSION(ipfw, 1);