/* * 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 (new version) */ #if !defined(KLD_MODULE) #include "opt_ipfw.h" #include "opt_ipdn.h" #include "opt_ipdivert.h" #include "opt_inet.h" #include "opt_ipsec.h" #ifndef INET #error IPFIREWALL requires INET. #endif /* INET */ #endif #define IPFW2 1 #if IPFW2 #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 #include #include #ifdef IPSEC #include #endif #include /* XXX for ETHERTYPE_IP */ #include /* XXX for in_cksum */ /* * This is used to avoid that a firewall-generated packet * loops forever through the firewall. Note that it must * be a flag that is unused by other protocols that might * be called from ip_output (e.g. IPsec) and it must be * listed in M_COPYFLAGS in mbuf.h so that if the mbuf chain * is altered on the way through ip_output it is not lost. * It might be better to add an m_tag since the this happens * infrequently. */ #define M_SKIP_FIREWALL M_PROTO6 /* * set_disable contains one bit per set value (0..31). * If the bit is set, all rules with the corresponding set * are disabled. Set RESVD_SET(31) is reserved for the default rule * and rules that are not deleted by the flush command, * and CANNOT be disabled. * Rules in set RESVD_SET can only be deleted explicitly. */ static u_int32_t set_disable; static int fw_verbose; static int verbose_limit; static struct callout ipfw_timeout; #define IPFW_DEFAULT_RULE 65535 /* * Data structure to cache our ucred related * information. This structure only gets used if * the user specified UID/GID based constraints in * a firewall rule. */ struct ip_fw_ugid { gid_t fw_groups[NGROUPS]; int fw_ngroups; uid_t fw_uid; }; struct ip_fw_chain { struct ip_fw *rules; /* list of rules */ struct ip_fw *reap; /* list of rules to reap */ struct mtx mtx; /* lock guarding rule list */ }; #define IPFW_LOCK_INIT(_chain) \ mtx_init(&(_chain)->mtx, "IPFW static rules", NULL, \ MTX_DEF | MTX_RECURSE) #define IPFW_LOCK_DESTROY(_chain) mtx_destroy(&(_chain)->mtx) #define IPFW_LOCK(_chain) mtx_lock(&(_chain)->mtx) #define IPFW_UNLOCK(_chain) mtx_unlock(&(_chain)->mtx) #define IPFW_LOCK_ASSERT(_chain) mtx_assert(&(_chain)->mtx, MA_OWNED) /* * list of rules for layer 3 */ static struct ip_fw_chain layer3_chain; MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); MALLOC_DEFINE(M_IPFW_TBL, "ipfw_tbl", "IpFw tables"); struct table_entry { struct radix_node rn[2]; struct sockaddr_in addr, mask; u_int32_t value; }; #define IPFW_TABLES_MAX 128 static struct { struct radix_node_head *rnh; int modified; } ipfw_tables[IPFW_TABLES_MAX]; static int fw_debug = 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 | CTLFLAG_SECURE3, &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 | CTLFLAG_SECURE3, &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 | CTLFLAG_SECURE3, &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 */ static struct mtx ipfw_dyn_mtx; /* mutex guarding dynamic rules */ #define IPFW_DYN_LOCK_INIT() \ mtx_init(&ipfw_dyn_mtx, "IPFW dynamic rules", NULL, MTX_DEF) #define IPFW_DYN_LOCK_DESTROY() mtx_destroy(&ipfw_dyn_mtx) #define IPFW_DYN_LOCK() mtx_lock(&ipfw_dyn_mtx) #define IPFW_DYN_UNLOCK() mtx_unlock(&ipfw_dyn_mtx) #define IPFW_DYN_LOCK_ASSERT() mtx_assert(&ipfw_dyn_mtx, MA_OWNED) /* * 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; /* * Keepalives are sent if dyn_keepalive is set. They are sent every * dyn_keepalive_period seconds, in the last dyn_keepalive_interval * seconds of lifetime of a rule. * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower * than dyn_keepalive_period. */ static u_int32_t dyn_keepalive_interval = 20; static u_int32_t dyn_keepalive_period = 5; static u_int32_t dyn_keepalive = 1; /* do send keepalives */ static u_int32_t static_count; /* # of static rules */ static u_int32_t static_len; /* size in bytes of static rules */ static u_int32_t dyn_count; /* # of dynamic rules */ static u_int32_t dyn_max = 4096; /* 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_keepalive, CTLFLAG_RW, &dyn_keepalive, 0, "Enable keepalives 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 __inline 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)); } 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') { /* match by name */ /* Check name */ if (cmd->p.glob) { if (fnmatch(cmd->name, ifp->if_xname, 0) == 0) return(1); } else { if (strncmp(ifp->if_xname, cmd->name, IFNAMSIZ) == 0) return(1); } } else { struct ifaddr *ia; /* XXX lock? */ 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 ... */ } /* * The verify_path function checks if a route to the src exists and * if it is reachable via ifp (when provided). * * The 'verrevpath' option checks that the interface that an IP packet * arrives on is the same interface that traffic destined for the * packet's source address would be routed out of. The 'versrcreach' * option just checks that the source address is reachable via any route * (except default) in the routing table. These two are a measure to block * forged packets. This is also commonly known as "anti-spoofing" or Unicast * Reverse Path Forwarding (Unicast RFP) in Cisco-ese. The name of the knobs * is purposely reminiscent of the Cisco IOS command, * * ip verify unicast reverse-path * ip verify unicast source reachable-via any * * which implements the same functionality. But note that syntax is * misleading. The check may be performed on all IP packets whether unicast, * multicast, or broadcast. */ static int verify_path(struct in_addr src, struct ifnet *ifp) { struct route ro; struct sockaddr_in *dst; bzero(&ro, sizeof(ro)); dst = (struct sockaddr_in *)&(ro.ro_dst); dst->sin_family = AF_INET; dst->sin_len = sizeof(*dst); dst->sin_addr = src; rtalloc_ign(&ro, RTF_CLONING); if (ro.ro_rt == NULL) return 0; /* if ifp is provided, check for equality with rtentry */ if (ifp != NULL && ro.ro_rt->rt_ifp != ifp) { RTFREE(ro.ro_rt); return 0; } /* if no ifp provided, check if rtentry is not default route */ if (ifp == NULL && satosin(rt_key(ro.ro_rt))->sin_addr.s_addr == INADDR_ANY) { RTFREE(ro.ro_rt); return 0; } /* found valid route */ RTFREE(ro.ro_rt); return 1; } static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */ #define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 #define SNP(buf) buf, sizeof(buf) /* * We enter here when we have a rule with O_LOG. * XXX this function alone takes about 2Kbytes of code! */ static void ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh, struct mbuf *m, struct ifnet *oif) { char *action; int limit_reached = 0; char action2[40], proto[48], fragment[28]; 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: if (cmd->arg1==ICMP_REJECT_RST) action = "Reset"; else if (cmd->arg1==ICMP_UNREACH_HOST) action = "Reject"; else snprintf(SNPARGS(action2, 0), "Unreach %d", cmd->arg1); 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; int len; len = snprintf(SNPARGS(action2, 0), "Forward to %s", inet_ntoa(sa->sa.sin_addr)); if (sa->sa.sin_port) snprintf(SNPARGS(action2, len), ":%d", sa->sa.sin_port); } 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) snprintf(SNPARGS(proto, len), ":%d %s:%d", ntohs(tcp->th_sport), inet_ntoa(ip->ip_dst), ntohs(tcp->th_dport)); else snprintf(SNPARGS(proto, len), " %s", inet_ntoa(ip->ip_dst)); break; case IPPROTO_UDP: len = snprintf(SNPARGS(proto, 0), "UDP %s", inet_ntoa(ip->ip_src)); if (offset == 0) snprintf(SNPARGS(proto, len), ":%d %s:%d", ntohs(udp->uh_sport), inet_ntoa(ip->ip_dst), ntohs(udp->uh_dport)); else snprintf(SNPARGS(proto, len), " %s", inet_ntoa(ip->ip_dst)); 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%s\n", f ? f->rulenum : -1, action, proto, oif ? "out" : "in", oif ? oif->if_xname : m->m_pkthdr.rcvif->if_xname, 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("ipfw: 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; IPFW_DYN_LOCK_ASSERT(); 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("ipfw: OUCH! cannot remove rule," " count %d\n", q->count); } } else { if (!FORCE && !TIME_LEQ( q->expire, time_second )) goto next; } if (q->dyn_type != O_LIMIT_PARENT || !q->count) { 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_locked(struct ipfw_flow_id *pkt, int *match_direction, struct tcphdr *tcp) { /* * 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; IPFW_DYN_LOCK_ASSERT(); 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 && q->count) 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 && q->dyn_type != O_LIMIT_PARENT) { 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 */ case BOTH_SYN | TH_FIN : /* one side tries to close */ case BOTH_SYN | (TH_FIN << 8) : if (tcp) { #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) u_int32_t ack = ntohl(tcp->th_ack); if (dir == MATCH_FORWARD) { if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd)) q->ack_fwd = ack; else { /* ignore out-of-sequence */ break; } } else { if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev)) q->ack_rev = ack; else { /* ignore out-of-sequence */ break; } } } q->expire = time_second + dyn_ack_lifetime; break; case BOTH_SYN | BOTH_FIN: /* both sides closed */ if (dyn_fin_lifetime >= dyn_keepalive_period) dyn_fin_lifetime = dyn_keepalive_period - 1; 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 if (dyn_rst_lifetime >= dyn_keepalive_period) dyn_rst_lifetime = dyn_keepalive_period - 1; 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 ipfw_dyn_rule * lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction, struct tcphdr *tcp) { ipfw_dyn_rule *q; IPFW_DYN_LOCK(); q = lookup_dyn_rule_locked(pkt, match_direction, tcp); if (q == NULL) IPFW_DYN_UNLOCK(); /* NB: return table locked when q is not NULL */ return q; } static void realloc_dynamic_table(void) { IPFW_DYN_LOCK_ASSERT(); /* * Try reallocation, make sure we have a power of 2 and do * not allow more than 64k entries. In case of overflow, * default to 1024. */ if (dyn_buckets > 65536) dyn_buckets = 1024; 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); for (;;) { ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *), M_IPFW, M_NOWAIT | M_ZERO); if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2) break; curr_dyn_buckets /= 2; } } /** * 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; IPFW_DYN_LOCK_ASSERT(); 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_NOWAIT | M_ZERO); if (r == NULL) { printf ("ipfw: 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("ipfw: 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; IPFW_DYN_LOCK_ASSERT(); 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("ipfw: 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("ipfw: 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) );) IPFW_DYN_LOCK(); q = lookup_dyn_rule_locked(&args->f_id, NULL, NULL); if (q != NULL) { /* should never occur */ if (last_log != time_second) { last_log = time_second; printf("ipfw: install_state: entry already present, done\n"); } IPFW_DYN_UNLOCK(); 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("ipfw: install_state: Too many dynamic rules\n"); } IPFW_DYN_UNLOCK(); 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("ipfw: 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("ipfw: 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; log(LOG_SECURITY | LOG_DEBUG, "drop session, too many entries\n"); } IPFW_DYN_UNLOCK(); return 1; } } add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent); } break; default: printf("ipfw: unknown dynamic rule type %u\n", cmd->o.opcode); IPFW_DYN_UNLOCK(); return 1; } lookup_dyn_rule_locked(&args->f_id, NULL, NULL); /* XXX just set lifetime */ IPFW_DYN_UNLOCK(); return 0; } /* * Transmit a TCP packet, containing either a RST or a keepalive. * When flags & TH_RST, we are sending a RST packet, because of a * "reset" action matched the packet. * Otherwise we are sending a keepalive, and flags & TH_ */ static void send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags) { struct mbuf *m; struct ip *ip; struct tcphdr *tcp; MGETHDR(m, M_DONTWAIT, MT_HEADER); if (m == 0) return; m->m_pkthdr.rcvif = (struct ifnet *)0; m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr); m->m_data += max_linkhdr; ip = mtod(m, struct ip *); bzero(ip, m->m_len); tcp = (struct tcphdr *)(ip + 1); /* no IP options */ ip->ip_p = IPPROTO_TCP; tcp->th_off = 5; /* * Assume we are sending a RST (or a keepalive in the reverse * direction), swap src and destination addresses and ports. */ ip->ip_src.s_addr = htonl(id->dst_ip); ip->ip_dst.s_addr = htonl(id->src_ip); tcp->th_sport = htons(id->dst_port); tcp->th_dport = htons(id->src_port); if (flags & TH_RST) { /* we are sending a RST */ if (flags & TH_ACK) { tcp->th_seq = htonl(ack); tcp->th_ack = htonl(0); tcp->th_flags = TH_RST; } else { if (flags & TH_SYN) seq++; tcp->th_seq = htonl(0); tcp->th_ack = htonl(seq); tcp->th_flags = TH_RST | TH_ACK; } } else { /* * We are sending a keepalive. flags & TH_SYN determines * the direction, forward if set, reverse if clear. * NOTE: seq and ack are always assumed to be correct * as set by the caller. This may be confusing... */ if (flags & TH_SYN) { /* * we have to rewrite the correct addresses! */ ip->ip_dst.s_addr = htonl(id->dst_ip); ip->ip_src.s_addr = htonl(id->src_ip); tcp->th_dport = htons(id->dst_port); tcp->th_sport = htons(id->src_port); } tcp->th_seq = htonl(seq); tcp->th_ack = htonl(ack); tcp->th_flags = TH_ACK; } /* * set ip_len to the payload size so we can compute * the tcp checksum on the pseudoheader * XXX check this, could save a couple of words ? */ ip->ip_len = htons(sizeof(struct tcphdr)); tcp->th_sum = in_cksum(m, m->m_pkthdr.len); /* * now fill fields left out earlier */ ip->ip_ttl = ip_defttl; ip->ip_len = m->m_pkthdr.len; m->m_flags |= M_SKIP_FIREWALL; ip_output(m, NULL, NULL, 0, NULL, NULL); } /* * sends a reject message, consuming the mbuf passed as an argument. */ static void send_reject(struct ip_fw_args *args, int code, int offset, int ip_len) { if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */ /* We need the IP header in host order for icmp_error(). */ if (args->eh != NULL) { struct ip *ip = mtod(args->m, struct ip *); ip->ip_len = ntohs(ip->ip_len); ip->ip_off = ntohs(ip->ip_off); } icmp_error(args->m, ICMP_UNREACH, code, 0L, 0); } else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) { struct tcphdr *const tcp = L3HDR(struct tcphdr, mtod(args->m, struct ip *)); if ( (tcp->th_flags & TH_RST) == 0) send_pkt(&(args->f_id), ntohl(tcp->th_seq), ntohl(tcp->th_ack), tcp->th_flags | TH_RST); m_freem(args->m); } else m_freem(args->m); args->m = NULL; } /** * * 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_LOG) cmd += F_LEN(cmd); 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; } static void init_tables(void) { int i; for (i = 0; i < IPFW_TABLES_MAX; i++) { rn_inithead((void **)&ipfw_tables[i].rnh, 32); ipfw_tables[i].modified = 1; } } static int add_table_entry(u_int16_t tbl, in_addr_t addr, u_int8_t mlen, u_int32_t value) { struct radix_node_head *rnh; struct table_entry *ent; if (tbl >= IPFW_TABLES_MAX) return (EINVAL); rnh = ipfw_tables[tbl].rnh; ent = malloc(sizeof(*ent), M_IPFW_TBL, M_NOWAIT | M_ZERO); if (ent == NULL) return (ENOMEM); ent->value = value; ent->addr.sin_len = ent->mask.sin_len = 8; ent->mask.sin_addr.s_addr = htonl(mlen ? ~((1 << (32 - mlen)) - 1) : 0); ent->addr.sin_addr.s_addr = addr & ent->mask.sin_addr.s_addr; RADIX_NODE_HEAD_LOCK(rnh); if (rnh->rnh_addaddr(&ent->addr, &ent->mask, rnh, (void *)ent) == NULL) { RADIX_NODE_HEAD_UNLOCK(rnh); free(ent, M_IPFW_TBL); return (EEXIST); } ipfw_tables[tbl].modified = 1; RADIX_NODE_HEAD_UNLOCK(rnh); return (0); } static int del_table_entry(u_int16_t tbl, in_addr_t addr, u_int8_t mlen) { struct radix_node_head *rnh; struct table_entry *ent; struct sockaddr_in sa, mask; if (tbl >= IPFW_TABLES_MAX) return (EINVAL); rnh = ipfw_tables[tbl].rnh; sa.sin_len = mask.sin_len = 8; mask.sin_addr.s_addr = htonl(mlen ? ~((1 << (32 - mlen)) - 1) : 0); sa.sin_addr.s_addr = addr & mask.sin_addr.s_addr; RADIX_NODE_HEAD_LOCK(rnh); ent = (struct table_entry *)rnh->rnh_deladdr(&sa, &mask, rnh); if (ent == NULL) { RADIX_NODE_HEAD_UNLOCK(rnh); return (ESRCH); } ipfw_tables[tbl].modified = 1; RADIX_NODE_HEAD_UNLOCK(rnh); free(ent, M_IPFW_TBL); return (0); } static int flush_table_entry(struct radix_node *rn, void *arg) { struct radix_node_head * const rnh = arg; struct table_entry *ent; ent = (struct table_entry *) rnh->rnh_deladdr(rn->rn_key, rn->rn_mask, rnh); if (ent != NULL) free(ent, M_IPFW_TBL); return (0); } static int flush_table(u_int16_t tbl) { struct radix_node_head *rnh; if (tbl >= IPFW_TABLES_MAX) return (EINVAL); rnh = ipfw_tables[tbl].rnh; RADIX_NODE_HEAD_LOCK(rnh); rnh->rnh_walktree(rnh, flush_table_entry, rnh); ipfw_tables[tbl].modified = 1; RADIX_NODE_HEAD_UNLOCK(rnh); return (0); } static void flush_tables(void) { u_int16_t tbl; for (tbl = 0; tbl < IPFW_TABLES_MAX; tbl++) flush_table(tbl); } static int lookup_table(u_int16_t tbl, in_addr_t addr, u_int32_t *val) { struct radix_node_head *rnh; struct table_entry *ent; struct sockaddr_in sa; static in_addr_t last_addr; static int last_tbl; static int last_match; static u_int32_t last_value; if (tbl >= IPFW_TABLES_MAX) return (0); if (tbl == last_tbl && addr == last_addr && !ipfw_tables[tbl].modified) { if (last_match) *val = last_value; return (last_match); } rnh = ipfw_tables[tbl].rnh; sa.sin_len = 8; sa.sin_addr.s_addr = addr; RADIX_NODE_HEAD_LOCK(rnh); ipfw_tables[tbl].modified = 0; ent = (struct table_entry *)(rnh->rnh_lookup(&sa, NULL, rnh)); RADIX_NODE_HEAD_UNLOCK(rnh); last_addr = addr; last_tbl = tbl; if (ent != NULL) { last_value = *val = ent->value; last_match = 1; return (1); } last_match = 0; return (0); } static int count_table_entry(struct radix_node *rn, void *arg) { u_int32_t * const cnt = arg; (*cnt)++; return (0); } static int count_table(u_int32_t tbl, u_int32_t *cnt) { struct radix_node_head *rnh; if (tbl >= IPFW_TABLES_MAX) return (EINVAL); rnh = ipfw_tables[tbl].rnh; *cnt = 0; RADIX_NODE_HEAD_LOCK(rnh); rnh->rnh_walktree(rnh, count_table_entry, cnt); RADIX_NODE_HEAD_UNLOCK(rnh); return (0); } static int dump_table_entry(struct radix_node *rn, void *arg) { struct table_entry * const n = (struct table_entry *)rn; ipfw_table * const tbl = arg; ipfw_table_entry *ent; if (tbl->cnt == tbl->size) return (1); ent = &tbl->ent[tbl->cnt]; ent->tbl = tbl->tbl; if (in_nullhost(n->mask.sin_addr)) ent->masklen = 0; else ent->masklen = 33 - ffs(ntohl(n->mask.sin_addr.s_addr)); ent->addr = n->addr.sin_addr.s_addr; ent->value = n->value; tbl->cnt++; return (0); } static int dump_table(ipfw_table *tbl) { struct radix_node_head *rnh; if (tbl->tbl >= IPFW_TABLES_MAX) return (EINVAL); rnh = ipfw_tables[tbl->tbl].rnh; tbl->cnt = 0; RADIX_NODE_HEAD_LOCK(rnh); rnh->rnh_walktree(rnh, dump_table_entry, tbl); RADIX_NODE_HEAD_UNLOCK(rnh); return (0); } static int check_uidgid(ipfw_insn_u32 *insn, int proto, struct ifnet *oif, struct in_addr dst_ip, u_int16_t dst_port, struct in_addr src_ip, u_int16_t src_port, struct ip_fw_ugid *ugp, int *lookup) { struct inpcbinfo *pi; int wildcard; struct inpcb *pcb; int match; struct ucred *cr; gid_t *gp; /* * If we have already been here and the packet has no * PCB entry associated with it, then we can safely * assume that this is a no match. */ if (*lookup == -1) return (0); if (proto == IPPROTO_TCP) { wildcard = 0; pi = &tcbinfo; } else if (proto == IPPROTO_UDP) { wildcard = 1; pi = &udbinfo; } else return 0; match = 0; if (*lookup == 0) { INP_INFO_RLOCK(pi); /* XXX LOR with IPFW */ 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) { INP_LOCK(pcb); if (pcb->inp_socket != NULL) { cr = pcb->inp_socket->so_cred; ugp->fw_uid = cr->cr_uid; ugp->fw_ngroups = cr->cr_ngroups; bcopy(cr->cr_groups, ugp->fw_groups, sizeof(ugp->fw_groups)); *lookup = 1; } INP_UNLOCK(pcb); } INP_INFO_RUNLOCK(pi); if (*lookup == 0) { /* * If the lookup did not yield any results, there * is no sense in coming back and trying again. So * we can set lookup to -1 and ensure that we wont * bother the pcb system again. */ *lookup = -1; return (0); } } if (insn->o.opcode == O_UID) match = (ugp->fw_uid == (uid_t)insn->d[0]); else if (insn->o.opcode == O_GID) for (gp = ugp->fw_groups; gp < &ugp->fw_groups[ugp->fw_ngroups]; gp++) if (*gp == (gid_t)insn->d[0]) { match = 1; break; } return match; } /* * 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 *); /* * For rules which contain uid/gid or jail constraints, cache * a copy of the users credentials after the pcb lookup has been * executed. This will speed up the processing of rules with * these types of constraints, as well as decrease contention * on pcb related locks. */ struct ip_fw_ugid fw_ugid_cache; int ugid_lookup = 0; /* * 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 pktlen; int dyn_dir = MATCH_UNKNOWN; ipfw_dyn_rule *q = NULL; struct ip_fw_chain *chain = &layer3_chain; struct m_tag *mtag; if (m->m_flags & M_SKIP_FIREWALL) return 0; /* accept */ /* * dyn_dir = MATCH_UNKNOWN when rules unchecked, * MATCH_NONE when checked and not matched (q = NULL), * MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL) */ pktlen = m->m_pkthdr.len; 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; } pktlen = ip_len < pktlen ? ip_len : pktlen; #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: IPFW_LOCK(chain); /* XXX expensive? can we run lock free? */ mtag = m_tag_find(m, PACKET_TAG_DIVERT, NULL); 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) { IPFW_UNLOCK(chain); /* XXX optimize */ 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 = mtag ? divert_cookie(mtag) : 0; f = chain->rules; if (args->eh == NULL && skipto != 0) { if (skipto >= IPFW_DEFAULT_RULE) { IPFW_UNLOCK(chain); return(IP_FW_PORT_DENY_FLAG); /* invalid */ } while (f && f->rulenum <= skipto) f = f->next; if (f == NULL) { /* drop packet */ IPFW_UNLOCK(chain); return(IP_FW_PORT_DENY_FLAG); } } } /* reset divert rule to avoid confusion later */ if (mtag) m_tag_delete(m, mtag); /* * 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: if (set_disable & (1 << f->set) ) continue; skip_or = 0; for (l = f->cmd_len, cmd = f->cmd ; l > 0 ; l -= cmdlen, cmd += cmdlen) { int match; /* * 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; } match = 0; /* set to 1 if we succeed */ switch (cmd->opcode) { /* * The first set of opcodes compares the packet's * fields with some pattern, setting 'match' if a * match is found. At the end of the loop there is * logic to deal with F_NOT and F_OR flags associated * with the opcode. */ case O_NOP: match = 1; break; case O_FORWARD_MAC: printf("ipfw: opcode %d unimplemented\n", cmd->opcode); break; 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) break; if (proto == IPPROTO_TCP || proto == IPPROTO_UDP) match = check_uidgid( (ipfw_insn_u32 *)cmd, proto, oif, dst_ip, dst_port, src_ip, src_port, &fw_ugid_cache, &ugid_lookup); break; case O_RECV: match = iface_match(m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd); break; case O_XMIT: match = iface_match(oif, (ipfw_insn_if *)cmd); break; case O_VIA: match = iface_match(oif ? oif : m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd); break; 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; match = ( want[0] == (hdr[0] & mask[0]) && want[1] == (hdr[1] & mask[1]) && want[2] == (hdr[2] & mask[2]) ); } break; case O_MAC_TYPE: if (args->eh != NULL) { u_int16_t t = ntohs(args->eh->ether_type); u_int16_t *p = ((ipfw_insn_u16 *)cmd)->ports; int i; for (i = cmdlen - 1; !match && i>0; i--, p += 2) match = (t>=p[0] && t<=p[1]); } break; case O_FRAG: match = (hlen > 0 && offset != 0); break; case O_IN: /* "out" is "not in" */ match = (oif == NULL); break; case O_LAYER2: match = (args->eh != NULL); break; case O_PROTO: /* * We do not allow an arg of 0 so the * check of "proto" only suffices. */ match = (proto == cmd->arg1); break; case O_IP_SRC: match = (hlen > 0 && ((ipfw_insn_ip *)cmd)->addr.s_addr == src_ip.s_addr); break; case O_IP_SRC_LOOKUP: case O_IP_DST_LOOKUP: if (hlen > 0) { uint32_t a = (cmd->opcode == O_IP_DST_LOOKUP) ? dst_ip.s_addr : src_ip.s_addr; uint32_t v; match = lookup_table(cmd->arg1, a, &v); if (!match) break; if (cmdlen == F_INSN_SIZE(ipfw_insn_u32)) match = ((ipfw_insn_u32 *)cmd)->d[0] == v; } break; case O_IP_SRC_MASK: case O_IP_DST_MASK: if (hlen > 0) { uint32_t a = (cmd->opcode == O_IP_DST_MASK) ? dst_ip.s_addr : src_ip.s_addr; uint32_t *p = ((ipfw_insn_u32 *)cmd)->d; int i = cmdlen-1; for (; !match && i>0; i-= 2, p+= 2) match = (p[0] == (a & p[1])); } break; case O_IP_SRC_ME: if (hlen > 0) { struct ifnet *tif; INADDR_TO_IFP(src_ip, tif); match = (tif != NULL); } break; case O_IP_DST_SET: case O_IP_SRC_SET: if (hlen > 0) { u_int32_t *d = (u_int32_t *)(cmd+1); u_int32_t addr = cmd->opcode == O_IP_DST_SET ? args->f_id.dst_ip : args->f_id.src_ip; if (addr < d[0]) break; addr -= d[0]; /* subtract base */ match = (addr < cmd->arg1) && ( d[ 1 + (addr>>5)] & (1<<(addr & 0x1f)) ); } break; case O_IP_DST: match = (hlen > 0 && ((ipfw_insn_ip *)cmd)->addr.s_addr == dst_ip.s_addr); break; case O_IP_DST_ME: if (hlen > 0) { struct ifnet *tif; INADDR_TO_IFP(dst_ip, tif); match = (tif != NULL); } break; 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 ((proto==IPPROTO_UDP || proto==IPPROTO_TCP) && offset == 0) { u_int16_t x = (cmd->opcode == O_IP_SRCPORT) ? src_port : dst_port ; u_int16_t *p = ((ipfw_insn_u16 *)cmd)->ports; int i; for (i = cmdlen - 1; !match && i>0; i--, p += 2) match = (x>=p[0] && x<=p[1]); } break; case O_ICMPTYPE: match = (offset == 0 && proto==IPPROTO_ICMP && icmptype_match(ip, (ipfw_insn_u32 *)cmd) ); break; case O_IPOPT: match = (hlen > 0 && ipopts_match(ip, cmd) ); break; case O_IPVER: match = (hlen > 0 && cmd->arg1 == ip->ip_v); break; case O_IPID: case O_IPLEN: case O_IPTTL: if (hlen > 0) { /* only for IP packets */ uint16_t x; uint16_t *p; int i; if (cmd->opcode == O_IPLEN) x = ip_len; else if (cmd->opcode == O_IPTTL) x = ip->ip_ttl; else /* must be IPID */ x = ntohs(ip->ip_id); if (cmdlen == 1) { match = (cmd->arg1 == x); break; } /* otherwise we have ranges */ p = ((ipfw_insn_u16 *)cmd)->ports; i = cmdlen - 1; for (; !match && i>0; i--, p += 2) match = (x >= p[0] && x <= p[1]); } break; case O_IPPRECEDENCE: match = (hlen > 0 && (cmd->arg1 == (ip->ip_tos & 0xe0)) ); break; case O_IPTOS: match = (hlen > 0 && flags_match(cmd, ip->ip_tos)); break; case O_TCPFLAGS: match = (proto == IPPROTO_TCP && offset == 0 && flags_match(cmd, L3HDR(struct tcphdr,ip)->th_flags)); break; case O_TCPOPTS: match = (proto == IPPROTO_TCP && offset == 0 && tcpopts_match(ip, cmd)); break; case O_TCPSEQ: match = (proto == IPPROTO_TCP && offset == 0 && ((ipfw_insn_u32 *)cmd)->d[0] == L3HDR(struct tcphdr,ip)->th_seq); break; case O_TCPACK: match = (proto == IPPROTO_TCP && offset == 0 && ((ipfw_insn_u32 *)cmd)->d[0] == L3HDR(struct tcphdr,ip)->th_ack); break; case O_TCPWIN: match = (proto == IPPROTO_TCP && offset == 0 && cmd->arg1 == L3HDR(struct tcphdr,ip)->th_win); break; case O_ESTAB: /* reject packets which have SYN only */ /* XXX should i also check for TH_ACK ? */ match = (proto == IPPROTO_TCP && offset == 0 && (L3HDR(struct tcphdr,ip)->th_flags & (TH_RST | TH_ACK | TH_SYN)) != TH_SYN); break; case O_LOG: if (fw_verbose) ipfw_log(f, hlen, args->eh, m, oif); match = 1; break; case O_PROB: match = (random()<((ipfw_insn_u32 *)cmd)->d[0]); break; case O_VERREVPATH: /* Outgoing packets automatically pass/match */ match = ((oif != NULL) || (m->m_pkthdr.rcvif == NULL) || verify_path(src_ip, m->m_pkthdr.rcvif)); break; case O_VERSRCREACH: /* Outgoing packets automatically pass/match */ match = ((oif != NULL) || verify_path(src_ip, NULL)); break; case O_IPSEC: #ifdef FAST_IPSEC match = (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL); #endif #ifdef IPSEC match = (ipsec_getnhist(m) != 0); #endif /* otherwise no match */ break; /* * The second set of opcodes represents 'actions', * i.e. the terminal part of a rule once the packet * matches all previous patterns. * Typically there is only one action for each rule, * and the opcode is stored at the end of the rule * (but there are exceptions -- see below). * * In general, here we set retval and terminate the * outer loop (would be a 'break 3' in some language, * but we need to do a 'goto done'). * * Exceptions: * O_COUNT and O_SKIPTO actions: * instead of terminating, we jump to the next rule * ('goto next_rule', equivalent to a 'break 2'), * or to the SKIPTO target ('goto again' after * having set f, cmd and l), respectively. * * O_LIMIT and O_KEEP_STATE: these opcodes are * not real 'actions', and are stored right * before the 'action' part of the rule. * These opcodes try to install an entry in the * state tables; if successful, we continue with * the next opcode (match=1; break;), otherwise * the packet * must be dropped * ('goto done' after setting retval); * * O_PROBE_STATE and O_CHECK_STATE: these opcodes * cause a lookup of the state table, and a jump * to the 'action' part of the parent rule * ('goto check_body') if an entry is found, or * (CHECK_STATE only) a jump to the next rule if * the entry is not found ('goto next_rule'). * The result of the lookup is cached to make * further instances of these opcodes are * effectively NOPs. */ case O_LIMIT: case O_KEEP_STATE: if (install_state(f, (ipfw_insn_limit *)cmd, args)) { retval = IP_FW_PORT_DENY_FLAG; goto done; /* error/limit violation */ } match = 1; break; case O_PROBE_STATE: case O_CHECK_STATE: /* * dynamic rules are checked at the first * keep-state or check-state occurrence, * with the result being stored in dyn_dir. * 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, proto == IPPROTO_TCP ? L3HDR(struct tcphdr, ip) : NULL)) != NULL) { /* * Found dynamic entry, update stats * and jump to the 'action' part of * the parent rule. */ q->pcnt++; q->bcnt += pktlen; f = q->rule; cmd = ACTION_PTR(f); l = f->cmd_len - f->act_ofs; IPFW_DYN_UNLOCK(); goto check_body; } /* * Dynamic entry not found. If CHECK_STATE, * skip to next rule, if PROBE_STATE just * ignore and continue with next opcode. */ if (cmd->opcode == O_CHECK_STATE) goto next_rule; match = 1; break; case O_ACCEPT: retval = 0; /* accept */ goto done; case O_PIPE: case O_QUEUE: args->rule = f; /* report matching rule */ retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG; goto done; case O_DIVERT: case O_TEE: { struct divert_tag *dt; if (args->eh) /* not on layer 2 */ break; mtag = m_tag_get(PACKET_TAG_DIVERT, sizeof(struct divert_tag), M_NOWAIT); if (mtag == NULL) { /* XXX statistic */ /* drop packet */ IPFW_UNLOCK(chain); return IP_FW_PORT_DENY_FLAG; } dt = (struct divert_tag *)(mtag+1); dt->cookie = f->rulenum; dt->info = (cmd->opcode == O_DIVERT) ? cmd->arg1 : cmd->arg1 | IP_FW_PORT_TEE_FLAG; m_tag_prepend(m, mtag); retval = dt->info; goto done; } case O_COUNT: case O_SKIPTO: f->pcnt++; /* update stats */ f->bcnt += pktlen; 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(ntohl(dst_ip.s_addr))) { send_reject(args, cmd->arg1, offset,ip_len); m = args->m; } /* FALLTHROUGH */ case O_DENY: retval = IP_FW_PORT_DENY_FLAG; goto done; case O_FORWARD_IP: if (args->eh) /* not valid on layer2 pkts */ break; if (!q || dyn_dir == MATCH_FORWARD) args->next_hop = &((ipfw_insn_sa *)cmd)->sa; retval = 0; goto done; default: panic("-- unknown opcode %d\n", cmd->opcode); } /* end of switch() on opcodes */ if (cmd->len & F_NOT) match = !match; if (match) { if (cmd->len & F_OR) skip_or = 1; } else { if (!(cmd->len & F_OR)) /* not an OR block, */ break; /* try next rule */ } } /* end of inner for, scan opcodes */ next_rule:; /* try next rule */ } /* end of outer for, scan rules */ printf("ipfw: ouch!, skip past end of rules, denying packet\n"); IPFW_UNLOCK(chain); return(IP_FW_PORT_DENY_FLAG); done: /* Update statistics */ f->pcnt++; f->bcnt += pktlen; f->timestamp = time_second; IPFW_UNLOCK(chain); return retval; pullup_failed: if (fw_verbose) printf("ipfw: pullup failed\n"); return(IP_FW_PORT_DENY_FLAG); } /* * 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. */ static void flush_rule_ptrs(struct ip_fw_chain *chain) { struct ip_fw *rule; IPFW_LOCK_ASSERT(chain); for (rule = chain->rules; 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). */ void flush_pipe_ptrs(struct dn_flow_set *match) { struct ip_fw *rule; IPFW_LOCK(&layer3_chain); for (rule = layer3_chain.rules; 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; /* * XXX Use bcmp/bzero to handle pipe_ptr to overcome * possible alignment problems on 64-bit architectures. * This code is seldom used so we do not worry too * much about efficiency. */ if (match == NULL || !bcmp(&cmd->pipe_ptr, &match, sizeof(match)) ) bzero(&cmd->pipe_ptr, sizeof(cmd->pipe_ptr)); } IPFW_UNLOCK(&layer3_chain); } /* * 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_chain *chain, struct ip_fw *input_rule) { struct ip_fw *rule, *f, *prev; int l = RULESIZE(input_rule); if (chain->rules == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE) return (EINVAL); rule = malloc(l, M_IPFW, M_NOWAIT | 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; IPFW_LOCK(chain); if (chain->rules == NULL) { /* default rule */ chain->rules = 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 = chain->rules; 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 = chain->rules; 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 = chain->rules; chain->rules = rule; } break; } } flush_rule_ptrs(chain); done: static_count++; static_len += l; IPFW_UNLOCK(chain); DEB(printf("ipfw: installed rule %d, static count now %d\n", rule->rulenum, static_count);) return (0); } /** * Remove a static rule (including derived * dynamic rules) * and place it on the ``reap list'' for later reclamation. * 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. */ static struct ip_fw * remove_rule(struct ip_fw_chain *chain, struct ip_fw *rule, struct ip_fw *prev) { struct ip_fw *n; int l = RULESIZE(rule); IPFW_LOCK_ASSERT(chain); n = rule->next; IPFW_DYN_LOCK(); remove_dyn_rule(rule, NULL /* force removal */); IPFW_DYN_UNLOCK(); if (prev == NULL) chain->rules = n; else prev->next = n; static_count--; static_len -= l; rule->next = chain->reap; chain->reap = rule; return n; } /** * Reclaim storage associated with a list of rules. This is * typically the list created using remove_rule. */ static void reap_rules(struct ip_fw *head) { struct ip_fw *rule; while ((rule = head) != NULL) { head = head->next; if (DUMMYNET_LOADED) ip_dn_ruledel_ptr(rule); free(rule, M_IPFW); } } /* * Remove all rules from a chain (except rules in set RESVD_SET * unless kill_default = 1). The caller is responsible for * reclaiming storage for the rules left in chain->reap. */ static void free_chain(struct ip_fw_chain *chain, int kill_default) { struct ip_fw *prev, *rule; IPFW_LOCK_ASSERT(chain); flush_rule_ptrs(chain); /* more efficient to do outside the loop */ for (prev = NULL, rule = chain->rules; rule ; ) if (kill_default || rule->set != RESVD_SET) rule = remove_rule(chain, rule, prev); else { prev = rule; rule = rule->next; } } /** * Remove all rules with given number, and also do set manipulation. * Assumes chain != NULL && *chain != NULL. * * The argument is an u_int32_t. The low 16 bit are the rule or set number, * the next 8 bits are the new set, the top 8 bits are the command: * * 0 delete rules with given number * 1 delete rules with given set number * 2 move rules with given number to new set * 3 move rules with given set number to new set * 4 swap sets with given numbers */ static int del_entry(struct ip_fw_chain *chain, u_int32_t arg) { struct ip_fw *prev = NULL, *rule; u_int16_t rulenum; /* rule or old_set */ u_int8_t cmd, new_set; rulenum = arg & 0xffff; cmd = (arg >> 24) & 0xff; new_set = (arg >> 16) & 0xff; if (cmd > 4) return EINVAL; if (new_set > RESVD_SET) return EINVAL; if (cmd == 0 || cmd == 2) { if (rulenum >= IPFW_DEFAULT_RULE) return EINVAL; } else { if (rulenum > RESVD_SET) /* old_set */ return EINVAL; } IPFW_LOCK(chain); rule = chain->rules; chain->reap = NULL; switch (cmd) { case 0: /* delete rules with given number */ /* * locate first rule to delete */ for (; rule->rulenum < rulenum; prev = rule, rule = rule->next) ; if (rule->rulenum != rulenum) { IPFW_UNLOCK(chain); return EINVAL; } /* * flush pointers outside the loop, then delete all matching * rules. prev remains the same throughout the cycle. */ flush_rule_ptrs(chain); while (rule->rulenum == rulenum) rule = remove_rule(chain, rule, prev); break; case 1: /* delete all rules with given set number */ flush_rule_ptrs(chain); rule = chain->rules; while (rule->rulenum < IPFW_DEFAULT_RULE) if (rule->set == rulenum) rule = remove_rule(chain, rule, prev); else { prev = rule; rule = rule->next; } break; case 2: /* move rules with given number to new set */ rule = chain->rules; for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next) if (rule->rulenum == rulenum) rule->set = new_set; break; case 3: /* move rules with given set number to new set */ for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next) if (rule->set == rulenum) rule->set = new_set; break; case 4: /* swap two sets */ for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next) if (rule->set == rulenum) rule->set = new_set; else if (rule->set == new_set) rule->set = rulenum; break; } /* * Look for rules to reclaim. We grab the list before * releasing the lock then reclaim them w/o the lock to * avoid a LOR with dummynet. */ rule = chain->reap; chain->reap = NULL; IPFW_UNLOCK(chain); if (rule) reap_rules(rule); return 0; } /* * Clear counters for a specific rule. * The enclosing "table" is assumed locked. */ 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(struct ip_fw_chain *chain, int rulenum, int log_only) { struct ip_fw *rule; char *msg; IPFW_LOCK(chain); if (rulenum == 0) { norule_counter = 0; for (rule = chain->rules; rule; rule = rule->next) clear_counters(rule, log_only); 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 = chain->rules; rule; rule = rule->next) if (rule->rulenum == rulenum) { while (rule && rule->rulenum == rulenum) { clear_counters(rule, log_only); rule = rule->next; } cleared = 1; break; } if (!cleared) { /* we did not find any matching rules */ IPFW_UNLOCK(chain); return (EINVAL); } msg = log_only ? "ipfw: Entry %d logging count reset.\n" : "ipfw: Entry %d cleared.\n"; } IPFW_UNLOCK(chain); 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("ipfw: rule too short\n"); return (EINVAL); } /* first, check for valid size */ l = RULESIZE(rule); if (l != size) { printf("ipfw: 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("ipfw: opcode %d size truncated\n", cmd->opcode); return EINVAL; } DEB(printf("ipfw: opcode %d\n", cmd->opcode);) switch (cmd->opcode) { 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_IPTOS: case O_IPPRECEDENCE: case O_IPVER: case O_TCPWIN: case O_TCPFLAGS: case O_TCPOPTS: case O_ESTAB: case O_VERREVPATH: case O_VERSRCREACH: case O_IPSEC: 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: /* only odd command lengths */ if ( !(cmdlen & 1) || cmdlen > 31) goto bad_size; break; case O_IP_SRC_SET: case O_IP_DST_SET: if (cmd->arg1 == 0 || cmd->arg1 > 256) { printf("ipfw: 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_IP_SRC_LOOKUP: case O_IP_DST_LOOKUP: if (cmd->arg1 >= IPFW_TABLES_MAX) { printf("ipfw: invalid table number %d\n", cmd->arg1); return (EINVAL); } if (cmdlen != F_INSN_SIZE(ipfw_insn) && cmdlen != F_INSN_SIZE(ipfw_insn_u32)) goto bad_size; break; case O_MACADDR2: if (cmdlen != F_INSN_SIZE(ipfw_insn_mac)) goto bad_size; break; case O_NOP: case O_IPID: case O_IPTTL: case O_IPLEN: if (cmdlen < 1 || cmdlen > 31) goto bad_size; break; case O_MAC_TYPE: case O_IP_SRCPORT: case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */ if (cmdlen < 2 || cmdlen > 31) 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: if (cmdlen != F_INSN_SIZE(ipfw_insn_sa)) goto bad_size; goto check_action; case O_FORWARD_MAC: /* XXX not implemented yet */ 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("ipfw: opcode %d, multiple actions" " not allowed\n", cmd->opcode); return EINVAL; } have_action = 1; if (l != cmdlen) { printf("ipfw: opcode %d, action must be" " last opcode\n", cmd->opcode); return EINVAL; } break; default: printf("ipfw: opcode %d, unknown opcode\n", cmd->opcode); return EINVAL; } } if (have_action == 0) { printf("ipfw: missing action\n"); return EINVAL; } return 0; bad_size: printf("ipfw: opcode %d size %d wrong\n", cmd->opcode, cmdlen); return EINVAL; } /* * Copy the static and dynamic rules to the supplied buffer * and return the amount of space actually used. */ static size_t ipfw_getrules(struct ip_fw_chain *chain, void *buf, size_t space) { char *bp = buf; char *ep = bp + space; struct ip_fw *rule; int i; /* XXX this can take a long time and locking will block packet flow */ IPFW_LOCK(chain); for (rule = chain->rules; rule ; rule = rule->next) { /* * Verify the entry fits in the buffer in case the * rules changed between calculating buffer space and * now. This would be better done using a generation * number but should suffice for now. */ i = RULESIZE(rule); if (bp + i <= ep) { bcopy(rule, bp, i); bcopy(&set_disable, &(((struct ip_fw *)bp)->next_rule), sizeof(set_disable)); bp += i; } } IPFW_UNLOCK(chain); if (ipfw_dyn_v) { ipfw_dyn_rule *p, *last = NULL; IPFW_DYN_LOCK(); for (i = 0 ; i < curr_dyn_buckets; i++) for (p = ipfw_dyn_v[i] ; p != NULL; p = p->next) { if (bp + sizeof *p <= ep) { ipfw_dyn_rule *dst = (ipfw_dyn_rule *)bp; bcopy(p, dst, sizeof *p); bcopy(&(p->rule->rulenum), &(dst->rule), sizeof(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. */ bcopy(&dst, &dst->next, sizeof(dst)); last = dst; dst->expire = TIME_LEQ(dst->expire, time_second) ? 0 : dst->expire - time_second ; bp += sizeof(ipfw_dyn_rule); } } IPFW_DYN_UNLOCK(); if (last != NULL) /* mark last dynamic rule */ bzero(&last->next, sizeof(last)); } return (bp - (char *)buf); } /** * {set|get}sockopt parser. */ static int ipfw_ctl(struct sockopt *sopt) { #define RULE_MAXSIZE (256*sizeof(u_int32_t)) int error, rule_num; size_t size; struct ip_fw *buf, *rule; u_int32_t rulenum[2]; error = suser(sopt->sopt_td); if (error) return (error); /* * 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. * * Note that the calculated size is used to bound the * amount of data returned to the user. The rule set may * change between calculating the size and returning the * data in which case we'll just return what fits. */ 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); error = sooptcopyout(sopt, buf, ipfw_getrules(&layer3_chain, 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. */ IPFW_LOCK(&layer3_chain); layer3_chain.reap = NULL; free_chain(&layer3_chain, 0 /* keep default rule */); rule = layer3_chain.reap, layer3_chain.reap = NULL; IPFW_UNLOCK(&layer3_chain); if (layer3_chain.reap != NULL) reap_rules(rule); break; case IP_FW_ADD: rule = malloc(RULE_MAXSIZE, M_TEMP, M_WAITOK); error = sooptcopyin(sopt, rule, RULE_MAXSIZE, sizeof(struct ip_fw) ); if (error == 0) error = check_ipfw_struct(rule, sopt->sopt_valsize); if (error == 0) { error = add_rule(&layer3_chain, rule); size = RULESIZE(rule); if (!error && sopt->sopt_dir == SOPT_GET) error = sooptcopyout(sopt, rule, size); } free(rule, M_TEMP); break; case IP_FW_DEL: /* * IP_FW_DEL is used for deleting single rules or sets, * and (ab)used to atomically manipulate sets. Argument size * is used to distinguish between the two: * sizeof(u_int32_t) * delete single rule or set of rules, * or reassign rules (or sets) to a different set. * 2*sizeof(u_int32_t) * atomic disable/enable sets. * first u_int32_t contains sets to be disabled, * second u_int32_t contains sets to be enabled. */ error = sooptcopyin(sopt, rulenum, 2*sizeof(u_int32_t), sizeof(u_int32_t)); if (error) break; size = sopt->sopt_valsize; if (size == sizeof(u_int32_t)) /* delete or reassign */ error = del_entry(&layer3_chain, rulenum[0]); else if (size == 2*sizeof(u_int32_t)) /* set enable/disable */ set_disable = (set_disable | rulenum[0]) & ~rulenum[1] & ~(1<sopt_val != 0) { error = sooptcopyin(sopt, &rule_num, sizeof(int), sizeof(int)); if (error) break; } error = zero_entry(&layer3_chain, rule_num, sopt->sopt_name == IP_FW_RESETLOG); break; case IP_FW_TABLE_ADD: { ipfw_table_entry ent; error = sooptcopyin(sopt, &ent, sizeof(ent), sizeof(ent)); if (error) break; error = add_table_entry(ent.tbl, ent.addr, ent.masklen, ent.value); } break; case IP_FW_TABLE_DEL: { ipfw_table_entry ent; error = sooptcopyin(sopt, &ent, sizeof(ent), sizeof(ent)); if (error) break; error = del_table_entry(ent.tbl, ent.addr, ent.masklen); } break; case IP_FW_TABLE_FLUSH: { u_int16_t tbl; error = sooptcopyin(sopt, &tbl, sizeof(tbl), sizeof(tbl)); if (error) break; error = flush_table(tbl); } break; case IP_FW_TABLE_GETSIZE: { u_int32_t tbl, cnt; if ((error = sooptcopyin(sopt, &tbl, sizeof(tbl), sizeof(tbl)))) break; if ((error = count_table(tbl, &cnt))) break; error = sooptcopyout(sopt, &cnt, sizeof(cnt)); } break; case IP_FW_TABLE_LIST: { ipfw_table *tbl; if (sopt->sopt_valsize < sizeof(*tbl)) { error = EINVAL; break; } size = sopt->sopt_valsize; tbl = malloc(size, M_TEMP, M_WAITOK); if (tbl == NULL) { error = ENOMEM; break; } error = sooptcopyin(sopt, tbl, size, sizeof(*tbl)); if (error) { free(tbl, M_TEMP); break; } tbl->size = (size - sizeof(*tbl)) / sizeof(ipfw_table_entry); error = dump_table(tbl); if (error) { free(tbl, M_TEMP); break; } error = sooptcopyout(sopt, tbl, size); free(tbl, M_TEMP); } break; default: printf("ipfw: ipfw_ctl invalid option %d\n", sopt->sopt_name); error = EINVAL; } return (error); #undef RULE_MAXSIZE } /** * 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; /* * This procedure is only used to handle keepalives. It is invoked * every dyn_keepalive_period */ static void ipfw_tick(void * __unused unused) { int i; ipfw_dyn_rule *q; if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0) goto done; IPFW_DYN_LOCK(); for (i = 0 ; i < curr_dyn_buckets ; i++) { for (q = ipfw_dyn_v[i] ; q ; q = q->next ) { if (q->dyn_type == O_LIMIT_PARENT) continue; if (q->id.proto != IPPROTO_TCP) continue; if ( (q->state & BOTH_SYN) != BOTH_SYN) continue; if (TIME_LEQ( time_second+dyn_keepalive_interval, q->expire)) continue; /* too early */ if (TIME_LEQ(q->expire, time_second)) continue; /* too late, rule expired */ send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0); } } IPFW_DYN_UNLOCK(); done: callout_reset(&ipfw_timeout, dyn_keepalive_period*hz, ipfw_tick, NULL); } static int ipfw_init(void) { struct ip_fw default_rule; int error; layer3_chain.rules = NULL; IPFW_LOCK_INIT(&layer3_chain); IPFW_DYN_LOCK_INIT(); callout_init(&ipfw_timeout, debug_mpsafenet ? CALLOUT_MPSAFE : 0); bzero(&default_rule, sizeof default_rule); default_rule.act_ofs = 0; default_rule.rulenum = IPFW_DEFAULT_RULE; default_rule.cmd_len = 1; default_rule.set = RESVD_SET; default_rule.cmd[0].len = 1; default_rule.cmd[0].opcode = #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT 1 ? O_ACCEPT : #endif O_DENY; error = add_rule(&layer3_chain, &default_rule); if (error != 0) { printf("ipfw2: error %u initializing default rule " "(support disabled)\n", error); IPFW_DYN_LOCK_DESTROY(); IPFW_LOCK_DESTROY(&layer3_chain); return (error); } ip_fw_default_rule = layer3_chain.rules; printf("ipfw2 initialized, divert %s, " "rule-based forwarding enabled, default to %s, logging ", #ifdef IPDIVERT "enabled", #else "disabled", #endif 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 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); ip_fw_chk_ptr = ipfw_chk; ip_fw_ctl_ptr = ipfw_ctl; callout_reset(&ipfw_timeout, hz, ipfw_tick, NULL); return (0); } static void ipfw_destroy(void) { struct ip_fw *reap; IPFW_LOCK(&layer3_chain); callout_stop(&ipfw_timeout); ip_fw_chk_ptr = NULL; ip_fw_ctl_ptr = NULL; layer3_chain.reap = NULL; free_chain(&layer3_chain, 1 /* kill default rule */); reap = layer3_chain.reap, layer3_chain.reap = NULL; IPFW_UNLOCK(&layer3_chain); if (reap != NULL) reap_rules(reap); flush_tables(); IPFW_DYN_LOCK_DESTROY(); IPFW_LOCK_DESTROY(&layer3_chain); printf("IP firewall unloaded\n"); } static int ipfw_modevent(module_t mod, int type, void *unused) { int err = 0; switch (type) { case MOD_LOAD: if (IPFW_LOADED) { printf("IP firewall already loaded\n"); err = EEXIST; } else { err = ipfw_init(); } break; case MOD_UNLOAD: ipfw_destroy(); err = 0; 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); /* Must be run after route_init(). */ SYSINIT(ipfw, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, init_tables, 0) #endif /* IPFW2 */