diff options
Diffstat (limited to 'sys/netinet/ip_fw.c')
| -rw-r--r-- | sys/netinet/ip_fw.c | 2082 |
1 files changed, 2082 insertions, 0 deletions
diff --git a/sys/netinet/ip_fw.c b/sys/netinet/ip_fw.c new file mode 100644 index 0000000..78c79cf --- /dev/null +++ b/sys/netinet/ip_fw.c @@ -0,0 +1,2082 @@ +/* + * Copyright (c) 1993 Daniel Boulet + * Copyright (c) 1994 Ugen J.S.Antsilevich + * Copyright (c) 1996 Alex Nash + * Copyright (c) 2000 Luigi Rizzo + * + * Redistribution and use in source forms, with and without modification, + * are permitted provided that this entire comment appears intact. + * + * Redistribution in binary form may occur without any restrictions. + * Obviously, it would be nice if you gave credit where credit is due + * but requiring it would be too onerous. + * + * This software is provided ``AS IS'' without any warranties of any kind. + * + * $FreeBSD$ + */ + +#define DEB(x) +#define DDB(x) x + +/* + * Implement IP packet firewall + */ + +#if !defined(KLD_MODULE) +#include "opt_ipfw.h" +#include "opt_ipdn.h" +#include "opt_ipdivert.h" +#include "opt_inet.h" +#ifndef INET +#error IPFIREWALL requires INET. +#endif /* INET */ +#endif + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/kernel.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/sysctl.h> +#include <sys/syslog.h> +#include <sys/ucred.h> +#include <net/if.h> +#include <net/route.h> +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/in_var.h> +#include <netinet/in_pcb.h> +#include <netinet/ip.h> +#include <netinet/ip_var.h> +#include <netinet/ip_icmp.h> +#include <netinet/ip_fw.h> +#ifdef DUMMYNET +#include <netinet/ip_dummynet.h> +#endif +#include <netinet/tcp.h> +#include <netinet/tcp_timer.h> +#include <netinet/tcp_var.h> +#include <netinet/tcpip.h> +#include <netinet/udp.h> +#include <netinet/udp_var.h> + +#include <netinet/if_ether.h> /* XXX ethertype_ip */ + +static int fw_debug = 1; +#ifdef IPFIREWALL_VERBOSE +static int fw_verbose = 1; +#else +static int fw_verbose = 0; +#endif +int fw_one_pass = 1 ; +#ifdef IPFIREWALL_VERBOSE_LIMIT +static int fw_verbose_limit = IPFIREWALL_VERBOSE_LIMIT; +#else +static int fw_verbose_limit = 0; +#endif +static int fw_permanent_rules = 0; + +/* + * Right now, two fields in the IP header are changed to host format + * by the IP layer before calling the firewall. Ideally, we would like + * to have them in network format so that the packet can be + * used as it comes from the device driver (and is thus readonly). + */ + +static u_int64_t counter; /* counter for ipfw_report(NULL...) */ +struct ipfw_flow_id last_pkt ; + +#define IPFW_DEFAULT_RULE ((u_int)(u_short)~0) + +LIST_HEAD (ip_fw_head, ip_fw_chain) ip_fw_chain_head; + +MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's"); + +#ifdef SYSCTL_NODE +SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW, + &fw_enable, 0, "Enable ipfw"); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW, + &fw_one_pass, 0, + "Only do a single pass through ipfw when using dummynet(4)"); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, + &fw_debug, 0, "Enable printing of debug ip_fw statements"); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, + &fw_verbose, 0, "Log matches to ipfw rules"); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, + &fw_verbose_limit, 0, "Set upper limit of matches of ipfw rules logged"); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, permanent_rules, CTLFLAG_RW, + &fw_permanent_rules, 0, "Set rule number, below which rules are permanent"); + +/* + * Extension for stateful ipfw. + * + * Dynamic rules are stored in lists accessed through a hash table + * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can + * be modified through the sysctl variable dyn_buckets which is + * updated when the table becomes empty. + * + * XXX currently there is only one list, ipfw_dyn. + * + * When a packet is received, it is first hashed, then matched + * against the entries in the corresponding list. + * Matching occurs according to the rule type. The default is to + * match the four fields and the protocol, and rules are bidirectional. + * + * For a busy proxy/web server we will have lots of connections to + * the server. We could decide for a rule type where we ignore + * ports (different hashing) and avoid special SYN/RST/FIN handling. + * + * XXX when we decide to support more than one rule type, we should + * repeat the hashing multiple times uing only the useful fields. + * Or, we could run the various tests in parallel, because the + * 'move to front' technique should shorten the average search. + * + * The lifetime of dynamic rules is regulated by dyn_*_lifetime, + * measured in seconds and depending on the flags. + * + * The total number of dynamic rules is stored in dyn_count. + * The max number of dynamic rules is dyn_max. When we reach + * the maximum number of rules we do not create anymore. This is + * done to avoid consuming too much memory, but also too much + * time when searching on each packet (ideally, we should try instead + * to put a limit on the length of the list on each bucket...). + * + * Each dynamic rules holds a pointer to the parent ipfw rule so + * we know what action to perform. Dynamic rules are removed when + * the parent rule is deleted. + * There are some limitations with dynamic rules -- we do not + * obey the 'randomized match', and we do not do multiple + * passes through the firewall. + * XXX check the latter!!! + */ +static struct ipfw_dyn_rule **ipfw_dyn_v = NULL ; +static u_int32_t dyn_buckets = 256 ; /* must be power of 2 */ +static u_int32_t curr_dyn_buckets = 256 ; /* must be power of 2 */ +static u_int32_t dyn_ack_lifetime = 300 ; +static u_int32_t dyn_syn_lifetime = 20 ; +static u_int32_t dyn_fin_lifetime = 20 ; +static u_int32_t dyn_rst_lifetime = 5 ; +static u_int32_t dyn_short_lifetime = 30 ; +static u_int32_t dyn_count = 0 ; +static u_int32_t dyn_max = 1000 ; +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, 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_short_lifetime, CTLFLAG_RW, + &dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations"); + +#endif + +#define dprintf(a) do { \ + if (fw_debug) \ + printf a; \ + } while (0) +#define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0 + +static int add_entry __P((struct ip_fw_head *chainptr, struct ip_fw *frwl)); +static int del_entry __P((struct ip_fw_head *chainptr, u_short number)); +static int zero_entry __P((struct ip_fw *)); +static int resetlog_entry __P((struct ip_fw *)); +static int check_ipfw_struct __P((struct ip_fw *m)); +static __inline int + iface_match __P((struct ifnet *ifp, union ip_fw_if *ifu, + int byname)); +static int ipopts_match __P((struct ip *ip, struct ip_fw *f)); +static int iptos_match __P((struct ip *ip, struct ip_fw *f)); +static __inline int + port_match __P((u_short *portptr, int nports, u_short port, + int range_flag, int mask)); +static int tcpflg_match __P((struct tcphdr *tcp, struct ip_fw *f)); +static int icmptype_match __P((struct icmp * icmp, struct ip_fw * f)); +static void ipfw_report __P((struct ip_fw *f, struct ip *ip, int offset, + struct ifnet *rif, struct ifnet *oif)); + +static void flush_rule_ptrs(void); + +static int ip_fw_chk __P((struct ip **pip, int hlen, + struct ifnet *oif, u_int16_t *cookie, struct mbuf **m, + struct ip_fw_chain **flow_id, + struct sockaddr_in **next_hop)); +static int ip_fw_ctl __P((struct sockopt *sopt)); + +static char err_prefix[] = "ip_fw_ctl:"; + +/* + * Returns 1 if the port is matched by the vector, 0 otherwise + */ +static __inline int +port_match(u_short *portptr, int nports, u_short port, int range_flag, int mask) +{ + if (!nports) + return 1; + if (mask) { + if ( 0 == ((portptr[0] ^ port) & portptr[1]) ) + return 1; + nports -= 2; + portptr += 2; + } + if (range_flag) { + if (portptr[0] <= port && port <= portptr[1]) { + return 1; + } + nports -= 2; + portptr += 2; + } + while (nports-- > 0) { + if (*portptr++ == port) { + return 1; + } + } + return 0; +} + +static int +tcpflg_match(struct tcphdr *tcp, struct ip_fw *f) +{ + u_char flg_set, flg_clr; + + /* + * If an established connection is required, reject packets that + * have only SYN of RST|ACK|SYN set. Otherwise, fall through to + * other flag requirements. + */ + if ((f->fw_ipflg & IP_FW_IF_TCPEST) && + ((tcp->th_flags & (IP_FW_TCPF_RST | IP_FW_TCPF_ACK | + IP_FW_TCPF_SYN)) == IP_FW_TCPF_SYN)) + return 0; + + flg_set = tcp->th_flags & f->fw_tcpf; + flg_clr = tcp->th_flags & f->fw_tcpnf; + + if (flg_set != f->fw_tcpf) + return 0; + if (flg_clr) + return 0; + + return 1; +} + +static int +icmptype_match(struct icmp *icmp, struct ip_fw *f) +{ + int type; + + if (!(f->fw_flg & IP_FW_F_ICMPBIT)) + return(1); + + type = icmp->icmp_type; + + /* check for matching type in the bitmap */ + if (type < IP_FW_ICMPTYPES_MAX && + (f->fw_uar.fw_icmptypes[type / (sizeof(unsigned) * NBBY)] & + (1U << (type % (sizeof(unsigned) * NBBY))))) + return(1); + + return(0); /* no match */ +} + +static int +is_icmp_query(struct ip *ip) +{ + const struct icmp *icmp; + int icmp_type; + + icmp = (struct icmp *)((u_int32_t *)ip + ip->ip_hl); + icmp_type = icmp->icmp_type; + + if (icmp_type == ICMP_ECHO || icmp_type == ICMP_ROUTERSOLICIT || + icmp_type == ICMP_TSTAMP || icmp_type == ICMP_IREQ || + icmp_type == ICMP_MASKREQ) + return(1); + + return(0); +} + +static int +ipopts_match(struct ip *ip, struct ip_fw *f) +{ + register u_char *cp; + int opt, optlen, cnt; + u_char opts, nopts, nopts_sve; + + cp = (u_char *)(ip + 1); + cnt = (ip->ip_hl << 2) - sizeof (struct ip); + opts = f->fw_ipopt; + nopts = nopts_sve = f->fw_ipnopt; + + for (; cnt > 0; cnt -= optlen, cp += optlen) { + opt = cp[IPOPT_OPTVAL]; + if (opt == IPOPT_EOL) + break; + if (opt == IPOPT_NOP) + optlen = 1; + else { + optlen = cp[IPOPT_OLEN]; + if (optlen <= 0 || optlen > cnt) { + return 0; /*XXX*/ + } + } + switch (opt) { + + default: + break; + + case IPOPT_LSRR: + opts &= ~IP_FW_IPOPT_LSRR; + nopts &= ~IP_FW_IPOPT_LSRR; + break; + + case IPOPT_SSRR: + opts &= ~IP_FW_IPOPT_SSRR; + nopts &= ~IP_FW_IPOPT_SSRR; + break; + + case IPOPT_RR: + opts &= ~IP_FW_IPOPT_RR; + nopts &= ~IP_FW_IPOPT_RR; + break; + case IPOPT_TS: + opts &= ~IP_FW_IPOPT_TS; + nopts &= ~IP_FW_IPOPT_TS; + break; + } + if (opts == nopts) + break; + } + if (opts == 0 && nopts == nopts_sve) + return 1; + else + return 0; +} + +static int +iptos_match(struct ip *ip, struct ip_fw *f) +{ + + u_int flags = (ip->ip_tos & 0x1f); + u_char opts, nopts, nopts_sve; + + opts = f->fw_iptos; + nopts = nopts_sve = f->fw_ipntos; + + while (flags != 0) { + u_int flag; + + flag = 1 << (ffs(flags) -1); + opts &= ~flag; + nopts &= ~flag; + flags &= ~flag; + } + + if (opts == 0 && nopts == nopts_sve) + return 1; + else + return 0; + +} + + +static int +tcpopts_match(struct tcphdr *tcp, struct ip_fw *f) +{ + register u_char *cp; + int opt, optlen, cnt; + u_char opts, nopts, nopts_sve; + + cp = (u_char *)(tcp + 1); + cnt = (tcp->th_off << 2) - sizeof (struct tcphdr); + opts = f->fw_tcpopt; + nopts = nopts_sve = f->fw_tcpnopt; + + for (; cnt > 0; cnt -= optlen, cp += optlen) { + opt = cp[0]; + if (opt == TCPOPT_EOL) + break; + if (opt == TCPOPT_NOP) + optlen = 1; + else { + optlen = cp[1]; + if (optlen <= 0) + break; + } + + + switch (opt) { + + default: + break; + + case TCPOPT_MAXSEG: + opts &= ~IP_FW_TCPOPT_MSS; + nopts &= ~IP_FW_TCPOPT_MSS; + break; + + case TCPOPT_WINDOW: + opts &= ~IP_FW_TCPOPT_WINDOW; + nopts &= ~IP_FW_TCPOPT_WINDOW; + break; + + case TCPOPT_SACK_PERMITTED: + case TCPOPT_SACK: + opts &= ~IP_FW_TCPOPT_SACK; + nopts &= ~IP_FW_TCPOPT_SACK; + break; + + case TCPOPT_TIMESTAMP: + opts &= ~IP_FW_TCPOPT_TS; + nopts &= ~IP_FW_TCPOPT_TS; + break; + + case TCPOPT_CC: + case TCPOPT_CCNEW: + case TCPOPT_CCECHO: + opts &= ~IP_FW_TCPOPT_CC; + nopts &= ~IP_FW_TCPOPT_CC; + break; + } + if (opts == nopts) + break; + } + if (opts == 0 && nopts == nopts_sve) + return 1; + else + return 0; +} + +static __inline int +iface_match(struct ifnet *ifp, union ip_fw_if *ifu, int byname) +{ + /* Check by name or by IP address */ + if (byname) { + /* Check unit number (-1 is wildcard) */ + if (ifu->fu_via_if.unit != -1 + && ifp->if_unit != ifu->fu_via_if.unit) + return(0); + /* Check name */ + if (strncmp(ifp->if_name, ifu->fu_via_if.name, FW_IFNLEN)) + return(0); + return(1); + } else if (ifu->fu_via_ip.s_addr != 0) { /* Zero == wildcard */ + struct ifaddr *ia; + + TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) { + if (ia->ifa_addr == NULL) + continue; + if (ia->ifa_addr->sa_family != AF_INET) + continue; + if (ifu->fu_via_ip.s_addr != ((struct sockaddr_in *) + (ia->ifa_addr))->sin_addr.s_addr) + continue; + return(1); + } + return(0); + } + return(1); +} + +static void +ipfw_report(struct ip_fw *f, struct ip *ip, int offset, + struct ifnet *rif, struct ifnet *oif) +{ + struct tcphdr *const tcp = (struct tcphdr *) ((u_int32_t *) ip+ ip->ip_hl); + struct udphdr *const udp = (struct udphdr *) ((u_int32_t *) ip+ ip->ip_hl); + struct icmp *const icmp = (struct icmp *) ((u_int32_t *) ip + ip->ip_hl); + u_int64_t count; + char *action; + char action2[32], proto[47], name[18], fragment[17]; + int len; + + count = f ? f->fw_pcnt : ++counter; + if ((f == NULL && fw_verbose_limit != 0 && count > fw_verbose_limit) || + (f && f->fw_logamount != 0 && count > f->fw_loghighest)) + return; + + /* Print command name */ + snprintf(SNPARGS(name, 0), "ipfw: %d", f ? f->fw_number : -1); + + action = action2; + if (!f) + action = "Refuse"; + else { + switch (f->fw_flg & IP_FW_F_COMMAND) { + case IP_FW_F_DENY: + action = "Deny"; + break; + case IP_FW_F_REJECT: + if (f->fw_reject_code == IP_FW_REJECT_RST) + action = "Reset"; + else + action = "Unreach"; + break; + case IP_FW_F_ACCEPT: + action = "Accept"; + break; + case IP_FW_F_COUNT: + action = "Count"; + break; +#ifdef IPDIVERT + case IP_FW_F_DIVERT: + snprintf(SNPARGS(action2, 0), "Divert %d", + f->fw_divert_port); + break; + case IP_FW_F_TEE: + snprintf(SNPARGS(action2, 0), "Tee %d", + f->fw_divert_port); + break; +#endif + case IP_FW_F_SKIPTO: + snprintf(SNPARGS(action2, 0), "SkipTo %d", + f->fw_skipto_rule); + break; +#ifdef DUMMYNET + case IP_FW_F_PIPE: + snprintf(SNPARGS(action2, 0), "Pipe %d", + f->fw_skipto_rule); + break; + case IP_FW_F_QUEUE: + snprintf(SNPARGS(action2, 0), "Queue %d", + f->fw_skipto_rule); + break; +#endif +#ifdef IPFIREWALL_FORWARD + case IP_FW_F_FWD: + if (f->fw_fwd_ip.sin_port) + snprintf(SNPARGS(action2, 0), + "Forward to %s:%d", + inet_ntoa(f->fw_fwd_ip.sin_addr), + f->fw_fwd_ip.sin_port); + else + snprintf(SNPARGS(action2, 0), "Forward to %s", + inet_ntoa(f->fw_fwd_ip.sin_addr)); + break; +#endif + default: + action = "UNKNOWN"; + break; + } + } + + switch (ip->ip_p) { + case IPPROTO_TCP: + len = snprintf(SNPARGS(proto, 0), "TCP %s", + inet_ntoa(ip->ip_src)); + if (offset == 0) + len += snprintf(SNPARGS(proto, len), ":%d ", + ntohs(tcp->th_sport)); + else + len += snprintf(SNPARGS(proto, len), " "); + len += snprintf(SNPARGS(proto, len), "%s", + inet_ntoa(ip->ip_dst)); + if (offset == 0) + snprintf(SNPARGS(proto, len), ":%d", + ntohs(tcp->th_dport)); + break; + case IPPROTO_UDP: + len = snprintf(SNPARGS(proto, 0), "UDP %s", + inet_ntoa(ip->ip_src)); + if (offset == 0) + len += snprintf(SNPARGS(proto, len), ":%d ", + ntohs(udp->uh_sport)); + else + len += snprintf(SNPARGS(proto, len), " "); + len += snprintf(SNPARGS(proto, len), "%s", + inet_ntoa(ip->ip_dst)); + if (offset == 0) + snprintf(SNPARGS(proto, len), ":%d", + ntohs(udp->uh_dport)); + break; + case IPPROTO_ICMP: + if (offset == 0) + len = snprintf(SNPARGS(proto, 0), "ICMP:%u.%u ", + icmp->icmp_type, icmp->icmp_code); + else + len = snprintf(SNPARGS(proto, 0), "ICMP "); + len += snprintf(SNPARGS(proto, len), "%s", + inet_ntoa(ip->ip_src)); + snprintf(SNPARGS(proto, len), " %s", inet_ntoa(ip->ip_dst)); + break; + default: + len = snprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p, + inet_ntoa(ip->ip_src)); + snprintf(SNPARGS(proto, len), " %s", inet_ntoa(ip->ip_dst)); + break; + } + + if (offset != 0) + snprintf(SNPARGS(fragment, 0), " Fragment = %d", + offset); + else + fragment[0] = '\0'; + if (oif) + log(LOG_SECURITY | LOG_INFO, "%s %s %s out via %s%d%s\n", + name, action, proto, oif->if_name, oif->if_unit, fragment); + else if (rif) + log(LOG_SECURITY | LOG_INFO, "%s %s %s in via %s%d%s\n", name, + action, proto, rif->if_name, rif->if_unit, fragment); + else + log(LOG_SECURITY | LOG_INFO, "%s %s %s%s\n", name, action, + proto, fragment); + if ((f ? f->fw_logamount != 0 : 1) && + count == (f ? f->fw_loghighest : fw_verbose_limit)) + log(LOG_SECURITY | LOG_NOTICE, + "ipfw: limit %d reached on entry %d\n", + f ? f->fw_logamount : fw_verbose_limit, + f ? f->fw_number : -1); +} + +static __inline int +hash_packet(struct ipfw_flow_id *id) +{ + u_int32_t i ; + + i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port); + i &= (curr_dyn_buckets - 1) ; + return i ; +} + +#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) +/* + * Remove all dynamic rules pointing to a given chain, or all + * rules if chain == NULL. Second parameter is 1 if we want to + * delete unconditionally, otherwise only expired rules are removed. + */ +static void +remove_dyn_rule(struct ip_fw_chain *chain, int force) +{ + struct ipfw_dyn_rule *prev, *q, *old_q ; + int i ; + static u_int32_t last_remove = 0 ; + + if (ipfw_dyn_v == NULL || dyn_count == 0) + return ; + /* do not expire more than once per second, it is useless */ + if (force == 0 && last_remove == time_second) + return ; + last_remove = time_second ; + + for (i = 0 ; i < curr_dyn_buckets ; i++) { + for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) { + if ( (chain == NULL || chain == q->chain) && + (force || TIME_LEQ( q->expire , time_second ) ) ) { + DEB(printf("-- remove 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 ); ) + old_q = q ; + if (prev != NULL) + prev->next = q = q->next ; + else + ipfw_dyn_v[i] = q = q->next ; + dyn_count-- ; + free(old_q, M_IPFW); + continue ; + } else { + prev = q ; + q = q->next ; + } + } + } +} + +static struct ipfw_dyn_rule * +lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction) +{ + /* + * stateful ipfw extensions. + * Lookup into dynamic session queue + */ + struct ipfw_dyn_rule *prev, *q, *old_q ; + int i, dir = 0; +#define MATCH_FORWARD 1 + + if (ipfw_dyn_v == NULL) + return NULL ; + i = hash_packet( pkt ); + for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) { + if (TIME_LEQ( q->expire , time_second ) ) { /* expire entry */ + old_q = q ; + if (prev != NULL) + prev->next = q = q->next ; + else + ipfw_dyn_v[i] = q = q->next ; + dyn_count-- ; + free(old_q, M_IPFW); + continue ; + } + if ( pkt->proto == q->id.proto) { + switch (q->type) { + default: /* bidirectional rule, no masks */ + if (pkt->src_ip == q->id.src_ip && + pkt->dst_ip == q->id.dst_ip && + pkt->src_port == q->id.src_port && + pkt->dst_port == q->id.dst_port ) { + dir = MATCH_FORWARD ; + goto found ; + } + if (pkt->src_ip == q->id.dst_ip && + pkt->dst_ip == q->id.src_ip && + pkt->src_port == q->id.dst_port && + pkt->dst_port == q->id.src_port ) { + dir = 0 ; /* reverse match */ + goto found ; + } + break ; + } + } + prev = q ; + q = q->next ; + } + return NULL ; /* clearly not found */ +found: + if ( prev != NULL) { /* found and not in front */ + prev->next = q->next ; + q->next = ipfw_dyn_v[i] ; + ipfw_dyn_v[i] = q ; + } + if (pkt->proto == IPPROTO_TCP) { + /* update state according to flags */ + u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST); + q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8); + switch (q->state) { + case TH_SYN : + /* opening */ + q->expire = time_second + dyn_syn_lifetime ; + break ; + case TH_SYN | (TH_SYN << 8) : + /* move to established */ + q->expire = time_second + dyn_ack_lifetime ; + break ; + case TH_SYN | (TH_SYN << 8) | TH_FIN : + case TH_SYN | (TH_SYN << 8) | (TH_FIN << 8) : + /* one side tries to close */ + q->expire = time_second + dyn_ack_lifetime ; + break ; + case TH_SYN | (TH_SYN << 8) | TH_FIN | (TH_FIN << 8) : + /* both sides closed */ + q->expire = time_second + dyn_fin_lifetime ; + break ; + default: +#if 0 + /* + * reset or some invalid combination, but can also + * occur if we use keep-state the wrong way. + */ + if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0) + printf("invalid state: 0x%x\n", q->state); +#endif + q->expire = time_second + dyn_rst_lifetime ; + break ; + } + } else { + /* should do something for UDP and others... */ + q->expire = time_second + dyn_short_lifetime ; + } + if (match_direction) + *match_direction = dir ; + return q ; +} + +/* + * Install state for a dynamic session. + */ + +static void +add_dyn_rule(struct ipfw_flow_id *id, struct ipfw_flow_id *mask, + struct ip_fw_chain *chain) +{ + struct ipfw_dyn_rule *r ; + + int i ; + if (ipfw_dyn_v == NULL || + (dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) { + /* try reallocation, make sure we have a power of 2 */ + u_int32_t i = dyn_buckets ; + while ( i > 0 && (i & 1) == 0 ) + i >>= 1 ; + if (i != 1) /* not a power of 2 */ + dyn_buckets = curr_dyn_buckets ; /* reset */ + else { + if (ipfw_dyn_v != NULL) + free(ipfw_dyn_v, M_IPFW); + ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof r, + M_IPFW, M_DONTWAIT | M_ZERO); + if (ipfw_dyn_v == NULL) + return ; /* 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 ; + } + + if (mask) + r->mask = *mask ; + r->id = *id ; + r->expire = time_second + dyn_syn_lifetime ; + r->chain = chain ; + r->type = ((struct ip_fw_ext *)chain->rule)->dyn_type ; + + r->bucket = i ; + r->next = ipfw_dyn_v[i] ; + ipfw_dyn_v[i] = r ; + dyn_count++ ; + DEB(printf("-- add entry 0x%08x %d -> 0x%08x %d, %d left\n", + (r->id.src_ip), (r->id.src_port), + (r->id.dst_ip), (r->id.dst_port), + dyn_count ); ) +} + +/* + * Install dynamic state. + * There are different types of dynamic rules which can be installed. + * The type is in chain->dyn_type. + * Type 0 (default) is a bidirectional rule + */ +static void +install_state(struct ip_fw_chain *chain) +{ + struct ipfw_dyn_rule *q ; + static int last_log ; + + u_long type = ((struct ip_fw_ext *)chain->rule)->dyn_type ; + + DEB(printf("-- install state type %d 0x%08lx %u -> 0x%08lx %u\n", + type, + (last_pkt.src_ip), (last_pkt.src_port), + (last_pkt.dst_ip), (last_pkt.dst_port) );) + + q = lookup_dyn_rule(&last_pkt, NULL) ; + if (q != NULL) { + if (last_log == time_second) + return ; + last_log = time_second ; + printf(" entry already present, done\n"); + return ; + } + if (dyn_count >= dyn_max) /* try remove old ones... */ + remove_dyn_rule(NULL, 0 /* expire */); + if (dyn_count >= dyn_max) { + if (last_log == time_second) + return ; + last_log = time_second ; + printf(" Too many dynamic rules, sorry\n"); + return ; + } + switch (type) { + default: /* bidir rule */ + add_dyn_rule(&last_pkt, NULL, chain); + break ; + } + q = lookup_dyn_rule(&last_pkt, NULL) ; /* XXX this just sets the lifetime ... */ +} + +/* + * given an ip_fw_chain *, lookup_next_rule will return a pointer + * of the same type to the next one. This can be either the jump + * target (for skipto instructions) or the next one in the chain (in + * all other cases including a missing jump target). + * Backward jumps are not allowed, so start looking from the next + * rule... + */ +static struct ip_fw_chain * lookup_next_rule(struct ip_fw_chain *me); + +static struct ip_fw_chain * +lookup_next_rule(struct ip_fw_chain *me) +{ + struct ip_fw_chain *chain ; + int rule = me->rule->fw_skipto_rule ; /* guess... */ + + if ( (me->rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_SKIPTO ) + for (chain = LIST_NEXT(me,next); chain ; chain = LIST_NEXT(chain,next)) + if (chain->rule->fw_number >= rule) + return chain ; + return LIST_NEXT(me,next) ; /* failure or not a skipto */ +} + +/* + * Parameters: + * + * pip Pointer to packet header (struct ip **) + * hlen Packet header length + * oif Outgoing interface, or NULL if packet is incoming + * *cookie Skip up to the first rule past this rule number; + * upon return, non-zero port number for divert or tee. + * Special case: cookie == NULL on input for bridging. + * *m The packet; we set to NULL when/if we nuke it. + * *flow_id pointer to the last matching rule (in/out) + * *next_hop socket we are forwarding to (in/out). + * + * Return value: + * + * IP_FW_PORT_DENY_FLAG the packet must be dropped. + * 0 The packet is to be accepted and routed normally OR + * the packet was denied/rejected and has been dropped; + * in the latter case, *m is equal to NULL upon return. + * port Divert the packet to port, with these caveats: + * + * - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead + * of diverting it (ie, 'ipfw tee'). + * + * - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower + * 16 bits as a dummynet pipe number instead of diverting + */ + +static int +ip_fw_chk(struct ip **pip, int hlen, + struct ifnet *oif, u_int16_t *cookie, struct mbuf **m, + struct ip_fw_chain **flow_id, + struct sockaddr_in **next_hop) +{ + struct ip_fw_chain *chain; + struct ip_fw *f = NULL, *rule = NULL; + struct ip *ip = *pip; + struct ifnet *const rif = (*m)->m_pkthdr.rcvif; + struct ifnet *tif; + u_short offset = 0 ; + u_short src_port = 0, dst_port = 0; + struct in_addr src_ip, dst_ip; /* XXX */ + u_int8_t proto= 0, flags = 0 ; /* XXX */ + u_int16_t skipto, bridgeCookie; + u_int16_t ip_len; + + int dyn_checked = 0 ; /* set after dyn.rules have been checked. */ + int direction = MATCH_FORWARD ; /* dirty trick... */ + struct ipfw_dyn_rule *q = NULL ; + + /* Special hack for bridging (as usual) */ + if (cookie == NULL) { + bridgeCookie = 0; + cookie = &bridgeCookie; +#define BRIDGED (cookie == &bridgeCookie) + hlen = ip->ip_hl << 2; + } + + /* Grab and reset cookie */ + skipto = *cookie; + *cookie = 0; + +#define PULLUP_TO(len) do { \ + if ((*m)->m_len < (len)) { \ + ip = NULL ; \ + if ((*m = m_pullup(*m, (len))) == 0) \ + goto bogusfrag; \ + ip = mtod(*m, struct ip *); \ + *pip = ip; \ + } \ + } while (0) + + /* + * Collect parameters into local variables for faster matching. + */ + proto = ip->ip_p; + src_ip = ip->ip_src; + dst_ip = ip->ip_dst; + if (0 && BRIDGED) { /* not yet... */ + offset = (ntohs(ip->ip_off) & IP_OFFMASK); + ip_len = ntohs(ip->ip_len); + } else { + offset = (ip->ip_off & IP_OFFMASK); + ip_len = ip->ip_len; + } + if (offset == 0) { + struct tcphdr *tcp; + struct udphdr *udp; + + switch (proto) { + case IPPROTO_TCP : + PULLUP_TO(hlen + sizeof(struct tcphdr)); + tcp =(struct tcphdr *)((u_int32_t *)ip + ip->ip_hl); + dst_port = tcp->th_dport ; + src_port = tcp->th_sport ; + flags = tcp->th_flags ; + break ; + + case IPPROTO_UDP : + PULLUP_TO(hlen + sizeof(struct udphdr)); + udp =(struct udphdr *)((u_int32_t *)ip + ip->ip_hl); + dst_port = udp->uh_dport ; + src_port = udp->uh_sport ; + break; + + case IPPROTO_ICMP: + PULLUP_TO(hlen + 4); /* type, code and checksum. */ + flags = ((struct icmp *) + ((u_int32_t *)ip + ip->ip_hl))->icmp_type ; + break ; + + default : + break; + } + } +#undef PULLUP_TO + last_pkt.src_ip = ntohl(src_ip.s_addr); + last_pkt.dst_ip = ntohl(dst_ip.s_addr); + last_pkt.proto = proto; + last_pkt.src_port = ntohs(src_port); + last_pkt.dst_port = ntohs(dst_port); + last_pkt.flags = flags; + + if (*flow_id) { + /* Accept if passed first test */ + if (fw_one_pass) + return 0; + /* + * Packet has already been tagged. Look for the next rule + * to restart processing. + */ + chain = LIST_NEXT(*flow_id, next); + + if ((chain = (*flow_id)->rule->next_rule_ptr) == NULL) + chain = (*flow_id)->rule->next_rule_ptr = + lookup_next_rule(*flow_id); + if (chain == NULL) + goto dropit; + } else { + /* + * Go down the chain, looking for enlightment. + * If we've been asked to start at a given rule, do so. + */ + chain = LIST_FIRST(&ip_fw_chain_head); + if (skipto != 0) { + if (skipto >= IPFW_DEFAULT_RULE) + goto dropit; + while (chain && chain->rule->fw_number <= skipto) + chain = LIST_NEXT(chain, next); + if (chain == NULL) + goto dropit; + } + } + + + for (; chain; chain = LIST_NEXT(chain, next)) { +again: + f = chain->rule; + if (f->fw_number == IPFW_DEFAULT_RULE) + goto got_match ; + + /* + * dynamic rules are checked at the first keep-state or + * check-state occurrence. + */ + if (f->fw_flg & (IP_FW_F_KEEP_S|IP_FW_F_CHECK_S) && + dyn_checked == 0 ) { + dyn_checked = 1 ; + q = lookup_dyn_rule(&last_pkt, &direction); + if (q != NULL) { + DEB(printf("-- dynamic match 0x%08x %d %s 0x%08x %d\n", + (q->id.src_ip), (q->id.src_port), + (direction == MATCH_FORWARD ? "-->" : "<--"), + (q->id.dst_ip), (q->id.dst_port) ); ) + chain = q->chain ; + f = chain->rule ; + q->pcnt++ ; + q->bcnt += ip_len; + goto got_match ; /* random not allowed here */ + } + /* if this was a check-only rule, continue with next */ + if (f->fw_flg & IP_FW_F_CHECK_S) + continue ; + } + + /* Check if rule only valid for bridged packets */ + if ((f->fw_flg & IP_FW_BRIDGED) != 0 && !(BRIDGED)) + continue; + + if (oif) { + /* Check direction outbound */ + if (!(f->fw_flg & IP_FW_F_OUT)) + continue; + } else { + /* Check direction inbound */ + if (!(f->fw_flg & IP_FW_F_IN)) + continue; + } + + /* Fragments */ + if ((f->fw_flg & IP_FW_F_FRAG) && offset == 0 ) + continue; + + if (f->fw_flg & IP_FW_F_SME) { + INADDR_TO_IFP(src_ip, tif); + if (tif == NULL) + continue; + } + if (f->fw_flg & IP_FW_F_DME) { + INADDR_TO_IFP(dst_ip, tif); + if (tif == NULL) + continue; + } + /* If src-addr doesn't match, not this rule. */ + if (((f->fw_flg & IP_FW_F_INVSRC) != 0) ^ ((src_ip.s_addr + & f->fw_smsk.s_addr) != f->fw_src.s_addr)) + continue; + + /* If dest-addr doesn't match, not this rule. */ + if (((f->fw_flg & IP_FW_F_INVDST) != 0) ^ ((dst_ip.s_addr + & f->fw_dmsk.s_addr) != f->fw_dst.s_addr)) + continue; + + /* Interface check */ + if ((f->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) { + struct ifnet *const iface = oif ? oif : rif; + + /* Backwards compatibility hack for "via" */ + if (!iface || !iface_match(iface, + &f->fw_in_if, f->fw_flg & IP_FW_F_OIFNAME)) + continue; + } else { + /* Check receive interface */ + if ((f->fw_flg & IP_FW_F_IIFACE) + && (!rif || !iface_match(rif, + &f->fw_in_if, f->fw_flg & IP_FW_F_IIFNAME))) + continue; + /* Check outgoing interface */ + if ((f->fw_flg & IP_FW_F_OIFACE) + && (!oif || !iface_match(oif, + &f->fw_out_if, f->fw_flg & IP_FW_F_OIFNAME))) + continue; + } + + /* Check IP header values */ + if (f->fw_ipflg & IP_FW_IF_IPOPT && !ipopts_match(ip, f)) + continue; + if (f->fw_ipflg & IP_FW_IF_IPLEN && f->fw_iplen != ip_len) + continue; + if (f->fw_ipflg & IP_FW_IF_IPID && f->fw_ipid != ntohs(ip->ip_id)) + continue; + if (f->fw_ipflg & IP_FW_IF_IPTOS && !iptos_match(ip, f)) + continue; + if (f->fw_ipflg & IP_FW_IF_IPTTL && f->fw_ipttl != ip->ip_ttl) + continue; + if (f->fw_ipflg & IP_FW_IF_IPVER && f->fw_ipver != ip->ip_v) + continue; + + /* Check protocol; if wildcard, and no [ug]id, match */ + if (f->fw_prot == IPPROTO_IP) { + if (!(f->fw_flg & (IP_FW_F_UID|IP_FW_F_GID))) + goto rnd_then_got_match; + } else + /* If different, don't match */ + if (proto != f->fw_prot) + continue; + + /* Protocol specific checks for uid only */ + if (f->fw_flg & (IP_FW_F_UID|IP_FW_F_GID)) { + switch (proto) { + case IPPROTO_TCP: + { + struct inpcb *P; + + if (offset == 1) /* cf. RFC 1858 */ + goto bogusfrag; + if (offset != 0) + continue; + + if (oif) + P = in_pcblookup_hash(&tcbinfo, dst_ip, + dst_port, src_ip, src_port, 0, + oif); + else + P = in_pcblookup_hash(&tcbinfo, src_ip, + src_port, dst_ip, dst_port, 0, + NULL); + + if (P && P->inp_socket) { + if (f->fw_flg & IP_FW_F_UID) { + if (P->inp_socket->so_cred->cr_uid != + f->fw_uid) + continue; + } else if (!groupmember(f->fw_gid, + P->inp_socket->so_cred)) + continue; + } else + continue; + break; + } + + case IPPROTO_UDP: + { + struct inpcb *P; + + if (offset != 0) + continue; + + if (oif) + P = in_pcblookup_hash(&udbinfo, dst_ip, + dst_port, src_ip, src_port, 1, + oif); + else + P = in_pcblookup_hash(&udbinfo, src_ip, + src_port, dst_ip, dst_port, 1, + NULL); + + if (P && P->inp_socket) { + if (f->fw_flg & IP_FW_F_UID) { + if (P->inp_socket->so_cred->cr_uid != + f->fw_uid) + continue; + } else if (!groupmember(f->fw_gid, + P->inp_socket->so_cred)) + continue; + } else + continue; + break; + } + + default: + continue; + } + } + + /* Protocol specific checks */ + switch (proto) { + case IPPROTO_TCP: + { + struct tcphdr *tcp; + + if (offset == 1) /* cf. RFC 1858 */ + goto bogusfrag; + if (offset != 0) { + /* + * TCP flags and ports aren't available in this + * packet -- if this rule specified either one, + * we consider the rule a non-match. + */ + if (f->fw_nports != 0 || + f->fw_ipflg & IP_FW_IF_TCPMSK) + continue; + + break; + } + tcp = (struct tcphdr *) ((u_int32_t *)ip + ip->ip_hl); + + if (f->fw_ipflg & IP_FW_IF_TCPOPT && !tcpopts_match(tcp, f)) + continue; + if (((f->fw_ipflg & IP_FW_IF_TCPFLG) || + (f->fw_ipflg & IP_FW_IF_TCPEST)) && + !tcpflg_match(tcp, f)) + continue; + if (f->fw_ipflg & IP_FW_IF_TCPSEQ && tcp->th_seq != f->fw_tcpseq) + continue; + if (f->fw_ipflg & IP_FW_IF_TCPACK && tcp->th_ack != f->fw_tcpack) + continue; + if (f->fw_ipflg & IP_FW_IF_TCPWIN && tcp->th_win != f->fw_tcpwin) + continue; + goto check_ports; + } + + case IPPROTO_UDP: + if (offset != 0) { + /* + * Port specification is unavailable -- if this + * rule specifies a port, we consider the rule + * a non-match. + */ + if (f->fw_nports != 0) + continue; + + break; + } +check_ports: + if (!port_match(&f->fw_uar.fw_pts[0], + IP_FW_GETNSRCP(f), ntohs(src_port), + f->fw_flg & IP_FW_F_SRNG, + f->fw_flg & IP_FW_F_SMSK)) + continue; + if (!port_match(&f->fw_uar.fw_pts[IP_FW_GETNSRCP(f)], + IP_FW_GETNDSTP(f), ntohs(dst_port), + f->fw_flg & IP_FW_F_DRNG, + f->fw_flg & IP_FW_F_DMSK)) + continue; + break; + + case IPPROTO_ICMP: + { + struct icmp *icmp; + + if (offset != 0) /* Type isn't valid */ + break; + icmp = (struct icmp *) ((u_int32_t *)ip + ip->ip_hl); + if (!icmptype_match(icmp, f)) + continue; + break; + } + + default: + break; + +bogusfrag: + if (fw_verbose && ip != NULL) + ipfw_report(NULL, ip, offset, rif, oif); + goto dropit; + + } + +rnd_then_got_match: + if ( ((struct ip_fw_ext *)f)->dont_match_prob && + random() < ((struct ip_fw_ext *)f)->dont_match_prob ) + continue ; +got_match: + /* + * If not a dynamic match (q == NULL) and keep-state, install + * a new dynamic entry. + */ + if (q == NULL && f->fw_flg & IP_FW_F_KEEP_S) + install_state(chain); + /* Update statistics */ + f->fw_pcnt += 1; + f->fw_bcnt += ip_len; + f->timestamp = time_second; + + /* Log to console if desired */ + if ((f->fw_flg & IP_FW_F_PRN) && fw_verbose) + ipfw_report(f, ip, offset, rif, oif); + + /* Take appropriate action */ + switch (f->fw_flg & IP_FW_F_COMMAND) { + case IP_FW_F_ACCEPT: + return(0); + case IP_FW_F_COUNT: + continue; +#ifdef IPDIVERT + case IP_FW_F_DIVERT: + *cookie = f->fw_number; + return(f->fw_divert_port); + case IP_FW_F_TEE: + *cookie = f->fw_number; + return(f->fw_divert_port | IP_FW_PORT_TEE_FLAG); +#endif + case IP_FW_F_SKIPTO: /* XXX check */ + if ( f->next_rule_ptr ) + chain = f->next_rule_ptr ; + else + chain = lookup_next_rule(chain) ; + if (! chain) goto dropit; + goto again ; +#ifdef DUMMYNET + case IP_FW_F_PIPE: + case IP_FW_F_QUEUE: + *flow_id = chain; + return(f->fw_pipe_nr | IP_FW_PORT_DYNT_FLAG); +#endif +#ifdef IPFIREWALL_FORWARD + case IP_FW_F_FWD: + /* Change the next-hop address for this packet. + * Initially we'll only worry about directly + * reachable next-hop's, but ultimately + * we will work out for next-hops that aren't + * direct the route we would take for it. We + * [cs]ould leave this latter problem to + * ip_output.c. We hope to high [name the abode of + * your favourite deity] that ip_output doesn't modify + * the new value of next_hop (which is dst there) + */ + if (next_hop != NULL /* Make sure, first... */ + && (q == NULL || direction == MATCH_FORWARD) ) + *next_hop = &(f->fw_fwd_ip); + return(0); /* Allow the packet */ +#endif + } + + /* Deny/reject this packet using this rule */ + rule = f; + break; + + } + + /* Rule IPFW_DEFAULT_RULE should always be there and match */ + KASSERT(chain != NULL, ("ip_fw: no chain")); + + /* + * At this point, we're going to drop the packet. + * Send a reject notice if all of the following are true: + * + * - The packet matched a reject rule + * - The packet is not an ICMP packet, or is an ICMP query packet + * - The packet is not a multicast or broadcast packet + */ + if ((rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_REJECT + && (ip->ip_p != IPPROTO_ICMP || is_icmp_query(ip)) + && !((*m)->m_flags & (M_BCAST|M_MCAST)) + && !IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { + switch (rule->fw_reject_code) { + case IP_FW_REJECT_RST: + { + /* XXX warning, this code writes into the mbuf */ + struct tcphdr *const tcp = + (struct tcphdr *) ((u_int32_t *)ip + ip->ip_hl); + struct tcpiphdr ti, *const tip = (struct tcpiphdr *) ip; + + if (offset != 0 || (tcp->th_flags & TH_RST)) + break; + ti.ti_i = *((struct ipovly *) ip); + ti.ti_t = *tcp; + bcopy(&ti, ip, sizeof(ti)); + NTOHL(tip->ti_seq); + NTOHL(tip->ti_ack); + tip->ti_len = ip_len - hlen - (tip->ti_off << 2); + if (tcp->th_flags & TH_ACK) { + tcp_respond(NULL, (void *)ip, tcp, *m, + (tcp_seq)0, tcp->th_ack, TH_RST); + } else { + if (tcp->th_flags & TH_SYN) + tip->ti_len++; + tcp_respond(NULL, (void *)ip, tcp, *m, + tip->ti_seq + tip->ti_len, + (tcp_seq)0, TH_RST|TH_ACK); + } + *m = NULL; + break; + } + default: /* Send an ICMP unreachable using code */ + icmp_error(*m, ICMP_UNREACH, + rule->fw_reject_code, 0L, 0); + *m = NULL; + break; + } + } + +dropit: + /* + * Finally, drop the packet. + */ + return(IP_FW_PORT_DENY_FLAG); +#undef BRIDGED +} + +/* + * when a rule is added/deleted, zero the direct pointers within + * all firewall rules. These will be reconstructed on the fly + * as packets are matched. + * Must be called at splnet(). + */ +static void +flush_rule_ptrs() +{ + struct ip_fw_chain *fcp ; + + LIST_FOREACH(fcp, &ip_fw_chain_head, next) { + fcp->rule->next_rule_ptr = NULL ; + } +} + +static int +add_entry(struct ip_fw_head *chainptr, struct ip_fw *frwl) +{ + struct ip_fw *ftmp = 0; + struct ip_fw_ext *ftmp_ext = 0 ; + struct ip_fw_chain *fwc = 0, *fcp, *fcpl = 0; + u_short nbr = 0; + int s; + + fwc = malloc(sizeof *fwc, M_IPFW, M_DONTWAIT); + ftmp_ext = malloc(sizeof *ftmp_ext, M_IPFW, M_DONTWAIT | M_ZERO); + ftmp = &ftmp_ext->rule ; + if (!fwc || !ftmp) { + dprintf(("%s malloc said no\n", err_prefix)); + if (fwc) free(fwc, M_IPFW); + if (ftmp) free(ftmp, M_IPFW); + return (ENOSPC); + } + + bcopy(frwl, ftmp, sizeof(*ftmp)); + if (ftmp->fw_flg & IP_FW_F_RND_MATCH) + ftmp_ext->dont_match_prob = (intptr_t)ftmp->pipe_ptr; + if (ftmp->fw_flg & IP_FW_F_KEEP_S) + ftmp_ext->dyn_type = (u_long)(ftmp->next_rule_ptr) ; + + ftmp->fw_in_if.fu_via_if.name[FW_IFNLEN - 1] = '\0'; + ftmp->fw_pcnt = 0L; + ftmp->fw_bcnt = 0L; + ftmp->next_rule_ptr = NULL ; + ftmp->pipe_ptr = NULL ; + fwc->rule = ftmp; + + s = splnet(); + + if (LIST_FIRST(chainptr) == 0) { + LIST_INSERT_HEAD(chainptr, fwc, next); + splx(s); + return(0); + } + + /* If entry number is 0, find highest numbered rule and add 100 */ + if (ftmp->fw_number == 0) { + LIST_FOREACH(fcp, chainptr, next) { + if (fcp->rule->fw_number != (u_short)-1) + nbr = fcp->rule->fw_number; + else + break; + } + if (nbr < IPFW_DEFAULT_RULE - 100) + nbr += 100; + ftmp->fw_number = frwl->fw_number = nbr; + } + + /* Got a valid number; now insert it, keeping the list ordered */ + LIST_FOREACH(fcp, chainptr, next) { + if (fcp->rule->fw_number > ftmp->fw_number) { + if (fcpl) { + LIST_INSERT_AFTER(fcpl, fwc, next); + } else { + LIST_INSERT_HEAD(chainptr, fwc, next); + } + break; + } else { + fcpl = fcp; + } + } + flush_rule_ptrs(); + + splx(s); + return (0); +} + +static int +del_entry(struct ip_fw_head *chainptr, u_short number) +{ + struct ip_fw_chain *fcp; + + fcp = LIST_FIRST(chainptr); + if (number != (u_short)-1) { + for (; fcp; fcp = LIST_NEXT(fcp, next)) { + if (fcp->rule->fw_number == number) { + int s; + + /* prevent access to rules while removing them */ + s = splnet(); + while (fcp && fcp->rule->fw_number == number) { + struct ip_fw_chain *next; + + remove_dyn_rule(fcp, 1 /* delete */); + next = LIST_NEXT(fcp, next); + LIST_REMOVE(fcp, next); +#ifdef DUMMYNET + dn_rule_delete(fcp) ; +#endif + flush_rule_ptrs(); + free(fcp->rule, M_IPFW); + free(fcp, M_IPFW); + fcp = next; + } + splx(s); + return 0; + } + } + } + + return (EINVAL); +} + +static int +zero_entry(struct ip_fw *frwl) +{ + struct ip_fw_chain *fcp; + int s, cleared; + + if (frwl == 0) { + s = splnet(); + LIST_FOREACH(fcp, &ip_fw_chain_head, next) { + fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0; + fcp->rule->fw_loghighest = fcp->rule->fw_logamount; + fcp->rule->timestamp = 0; + } + splx(s); + } + else { + cleared = 0; + + /* + * It's possible to insert multiple chain entries with the + * same number, so we don't stop after finding the first + * match if zeroing a specific entry. + */ + LIST_FOREACH(fcp, &ip_fw_chain_head, next) + if (frwl->fw_number == fcp->rule->fw_number) { + s = splnet(); + while (fcp && frwl->fw_number == fcp->rule->fw_number) { + fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0; + fcp->rule->fw_loghighest = + fcp->rule->fw_logamount; + fcp->rule->timestamp = 0; + fcp = LIST_NEXT(fcp, next); + } + splx(s); + cleared = 1; + break; + } + if (!cleared) /* we didn't find any matching rules */ + return (EINVAL); + } + + if (fw_verbose) { + if (frwl) + log(LOG_SECURITY | LOG_NOTICE, + "ipfw: Entry %d cleared.\n", frwl->fw_number); + else + log(LOG_SECURITY | LOG_NOTICE, + "ipfw: Accounting cleared.\n"); + } + + return (0); +} + +static int +resetlog_entry(struct ip_fw *frwl) +{ + struct ip_fw_chain *fcp; + int s, cleared; + + if (frwl == 0) { + s = splnet(); + counter = 0; + LIST_FOREACH(fcp, &ip_fw_chain_head, next) + fcp->rule->fw_loghighest = fcp->rule->fw_pcnt + + fcp->rule->fw_logamount; + splx(s); + } + else { + cleared = 0; + + /* + * It's possible to insert multiple chain entries with the + * same number, so we don't stop after finding the first + * match if zeroing a specific entry. + */ + LIST_FOREACH(fcp, &ip_fw_chain_head, next) + if (frwl->fw_number == fcp->rule->fw_number) { + s = splnet(); + while (fcp && frwl->fw_number == fcp->rule->fw_number) { + fcp->rule->fw_loghighest = + fcp->rule->fw_pcnt + + fcp->rule->fw_logamount; + fcp = LIST_NEXT(fcp, next); + } + splx(s); + cleared = 1; + break; + } + if (!cleared) /* we didn't find any matching rules */ + return (EINVAL); + } + + if (fw_verbose) { + if (frwl) + log(LOG_SECURITY | LOG_NOTICE, + "ipfw: Entry %d logging count reset.\n", + frwl->fw_number); + else + log(LOG_SECURITY | LOG_NOTICE, " + ipfw: All logging counts cleared.\n"); + } + + return (0); +} + +static int +check_ipfw_struct(struct ip_fw *frwl) +{ + /* Check for invalid flag bits */ + if ((frwl->fw_flg & ~IP_FW_F_MASK) != 0) { + dprintf(("%s undefined flag bits set (flags=%x)\n", + err_prefix, frwl->fw_flg)); + return (EINVAL); + } + if (frwl->fw_flg == IP_FW_F_CHECK_S) { + /* check-state */ + return 0 ; + } + /* Must apply to incoming or outgoing (or both) */ + if (!(frwl->fw_flg & (IP_FW_F_IN | IP_FW_F_OUT))) { + dprintf(("%s neither in nor out\n", err_prefix)); + return (EINVAL); + } + /* Empty interface name is no good */ + if (((frwl->fw_flg & IP_FW_F_IIFNAME) + && !*frwl->fw_in_if.fu_via_if.name) + || ((frwl->fw_flg & IP_FW_F_OIFNAME) + && !*frwl->fw_out_if.fu_via_if.name)) { + dprintf(("%s empty interface name\n", err_prefix)); + return (EINVAL); + } + /* Sanity check interface matching */ + if ((frwl->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) { + ; /* allow "via" backwards compatibility */ + } else if ((frwl->fw_flg & IP_FW_F_IN) + && (frwl->fw_flg & IP_FW_F_OIFACE)) { + dprintf(("%s outgoing interface check on incoming\n", + err_prefix)); + return (EINVAL); + } + /* Sanity check port ranges */ + if ((frwl->fw_flg & IP_FW_F_SRNG) && IP_FW_GETNSRCP(frwl) < 2) { + dprintf(("%s src range set but n_src_p=%d\n", + err_prefix, IP_FW_GETNSRCP(frwl))); + return (EINVAL); + } + if ((frwl->fw_flg & IP_FW_F_DRNG) && IP_FW_GETNDSTP(frwl) < 2) { + dprintf(("%s dst range set but n_dst_p=%d\n", + err_prefix, IP_FW_GETNDSTP(frwl))); + return (EINVAL); + } + if (IP_FW_GETNSRCP(frwl) + IP_FW_GETNDSTP(frwl) > IP_FW_MAX_PORTS) { + dprintf(("%s too many ports (%d+%d)\n", + err_prefix, IP_FW_GETNSRCP(frwl), IP_FW_GETNDSTP(frwl))); + return (EINVAL); + } + /* + * Protocols other than TCP/UDP don't use port range + */ + if ((frwl->fw_prot != IPPROTO_TCP) && + (frwl->fw_prot != IPPROTO_UDP) && + (IP_FW_GETNSRCP(frwl) || IP_FW_GETNDSTP(frwl))) { + dprintf(("%s port(s) specified for non TCP/UDP rule\n", + err_prefix)); + return (EINVAL); + } + + /* + * Rather than modify the entry to make such entries work, + * we reject this rule and require user level utilities + * to enforce whatever policy they deem appropriate. + */ + if ((frwl->fw_src.s_addr & (~frwl->fw_smsk.s_addr)) || + (frwl->fw_dst.s_addr & (~frwl->fw_dmsk.s_addr))) { + dprintf(("%s rule never matches\n", err_prefix)); + return (EINVAL); + } + + if ((frwl->fw_flg & IP_FW_F_FRAG) && + (frwl->fw_prot == IPPROTO_UDP || frwl->fw_prot == IPPROTO_TCP)) { + if (frwl->fw_nports) { + dprintf(("%s cannot mix 'frag' and ports\n", err_prefix)); + return (EINVAL); + } + if (frwl->fw_prot == IPPROTO_TCP && + frwl->fw_tcpf != frwl->fw_tcpnf) { + dprintf(("%s cannot mix 'frag' and TCP flags\n", err_prefix)); + return (EINVAL); + } + } + + if (frwl->fw_flg & (IP_FW_F_UID | IP_FW_F_GID)) { + if ((frwl->fw_prot != IPPROTO_TCP) && + (frwl->fw_prot != IPPROTO_UDP) && + (frwl->fw_prot != IPPROTO_IP)) { + dprintf(("%s cannot use uid/gid logic on non-TCP/UDP\n", err_prefix)); + return (EINVAL); + } + } + + /* Check command specific stuff */ + switch (frwl->fw_flg & IP_FW_F_COMMAND) + { + case IP_FW_F_REJECT: + if (frwl->fw_reject_code >= 0x100 + && !(frwl->fw_prot == IPPROTO_TCP + && frwl->fw_reject_code == IP_FW_REJECT_RST)) { + dprintf(("%s unknown reject code\n", err_prefix)); + return (EINVAL); + } + break; +#if defined(IPDIVERT) || defined(DUMMYNET) +#ifdef IPDIVERT + case IP_FW_F_DIVERT: /* Diverting to port zero is invalid */ + case IP_FW_F_TEE: +#endif +#ifdef DUMMYNET + case IP_FW_F_PIPE: /* piping through 0 is invalid */ + case IP_FW_F_QUEUE: /* piping through 0 is invalid */ +#endif + if (frwl->fw_divert_port == 0) { + dprintf(("%s can't divert to port 0\n", err_prefix)); + return (EINVAL); + } + break; +#endif /* IPDIVERT || DUMMYNET */ + case IP_FW_F_DENY: + case IP_FW_F_ACCEPT: + case IP_FW_F_COUNT: + case IP_FW_F_SKIPTO: +#ifdef IPFIREWALL_FORWARD + case IP_FW_F_FWD: +#endif + break; + default: + dprintf(("%s invalid command\n", err_prefix)); + return (EINVAL); + } + + return 0; +} + +static int +ip_fw_ctl(struct sockopt *sopt) +{ + int error, s; + size_t size; + struct ip_fw_chain *fcp; + struct ip_fw frwl, *bp , *buf; + + /* + * Disallow modifications in really-really secure mode, but still allow + * the logging counters to be reset. + */ + if (securelevel >= 3 && (sopt->sopt_name == IP_FW_ADD || + (sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG))) + return (EPERM); + error = 0; + + switch (sopt->sopt_name) { + case IP_FW_GET: + size = 0 ; + LIST_FOREACH(fcp, &ip_fw_chain_head, next) + size += sizeof(struct ip_fw) ; + if (ipfw_dyn_v) { + int i ; + struct ipfw_dyn_rule *p ; + + for (i = 0 ; i < curr_dyn_buckets ; i++ ) + for ( p = ipfw_dyn_v[i] ; p != NULL ; p = p->next ) + size += sizeof(*p) ; + } + buf = malloc(size, M_TEMP, M_WAITOK); + if (buf == 0) { + error = ENOBUFS; + break; + } + + bp = buf ; + LIST_FOREACH(fcp, &ip_fw_chain_head, next) { + bcopy(fcp->rule, bp, sizeof *fcp->rule); + bp->pipe_ptr = (void *)(intptr_t) + ((struct ip_fw_ext *)fcp->rule)->dont_match_prob; + bp->next_rule_ptr = (void *)(intptr_t) + ((struct ip_fw_ext *)fcp->rule)->dyn_type; + bp++; + } + if (ipfw_dyn_v) { + int i ; + struct ipfw_dyn_rule *p, *dst, *last = NULL ; + + dst = (struct ipfw_dyn_rule *)bp ; + for (i = 0 ; i < curr_dyn_buckets ; i++ ) + for ( p = ipfw_dyn_v[i] ; p != NULL ; p = p->next, dst++ ) { + bcopy(p, dst, sizeof *p); + (int)dst->chain = p->chain->rule->fw_number ; + dst->next = dst ; /* fake non-null pointer... */ + last = dst ; + if (TIME_LEQ(dst->expire, time_second) ) + dst->expire = 0 ; + else + dst->expire -= time_second ; + } + if (last != NULL) + last->next = NULL ; + } + error = sooptcopyout(sopt, buf, size); + FREE(buf, M_TEMP); + break; + + case IP_FW_FLUSH: + s = splnet(); + remove_dyn_rule(NULL, 1 /* force delete */); + splx(s); + fcp = LIST_FIRST(&ip_fw_chain_head); + while (fcp) { + struct ip_fw_chain *next; + next = LIST_NEXT(fcp, next); + if (fcp->rule->fw_number > fw_permanent_rules && + fcp->rule->fw_number != IPFW_DEFAULT_RULE ) { + s = splnet(); + LIST_REMOVE(fcp, next); +#ifdef DUMMYNET + dn_rule_delete(fcp); +#endif + FREE(fcp->rule, M_IPFW); + FREE(fcp, M_IPFW); + splx(s); + } + fcp = next; + } + break; + + case IP_FW_ZERO: + if (sopt->sopt_val != 0) { + error = sooptcopyin(sopt, &frwl, sizeof frwl, + sizeof frwl); + if (error || (error = zero_entry(&frwl))) + break; + } else { + error = zero_entry(0); + } + break; + + case IP_FW_ADD: + error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl); + if (error || (error = check_ipfw_struct(&frwl))) + break; + + if (frwl.fw_number == IPFW_DEFAULT_RULE) { + dprintf(("%s can't add rule %u\n", err_prefix, + (unsigned)IPFW_DEFAULT_RULE)); + error = EINVAL; + } else { + error = add_entry(&ip_fw_chain_head, &frwl); + if (!error && sopt->sopt_dir == SOPT_GET) + error = sooptcopyout(sopt, &frwl, sizeof frwl); + } + break; + + case IP_FW_DEL: + error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl); + if (error) + break; + + if (frwl.fw_number == IPFW_DEFAULT_RULE) { + dprintf(("%s can't delete rule %u\n", err_prefix, + (unsigned)IPFW_DEFAULT_RULE)); + error = EINVAL; + } else { + error = del_entry(&ip_fw_chain_head, frwl.fw_number); + } + break; + + case IP_FW_RESETLOG: + if (sopt->sopt_val != 0) { + error = sooptcopyin(sopt, &frwl, sizeof frwl, + sizeof frwl); + if (error || (error = resetlog_entry(&frwl))) + break; + } else { + error = resetlog_entry(0); + } + break; + + default: + printf("ip_fw_ctl invalid option %d\n", sopt->sopt_name); + error = EINVAL ; + } + + return (error); +} + +struct ip_fw_chain *ip_fw_default_rule ; + +void +ip_fw_init(void) +{ + struct ip_fw default_rule; + + ip_fw_chk_ptr = ip_fw_chk; + ip_fw_ctl_ptr = ip_fw_ctl; + LIST_INIT(&ip_fw_chain_head); + + bzero(&default_rule, sizeof default_rule); + default_rule.fw_prot = IPPROTO_IP; + default_rule.fw_number = IPFW_DEFAULT_RULE; +#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT + default_rule.fw_flg |= IP_FW_F_ACCEPT; +#else + default_rule.fw_flg |= IP_FW_F_DENY; +#endif + default_rule.fw_flg |= IP_FW_F_IN | IP_FW_F_OUT; + if (check_ipfw_struct(&default_rule) != 0 || + add_entry(&ip_fw_chain_head, &default_rule)) + panic("ip_fw_init"); + + ip_fw_default_rule = LIST_FIRST(&ip_fw_chain_head) ; + printf("IP packet filtering initialized, " +#ifdef IPDIVERT + "divert enabled, " +#else + "divert disabled, " +#endif +#ifdef IPFIREWALL_FORWARD + "rule-based forwarding enabled, " +#else + "rule-based forwarding disabled, " +#endif +#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT + "default to accept, "); +#else + "default to deny, " ); +#endif +#ifndef IPFIREWALL_VERBOSE + printf("logging disabled\n"); +#else + if (fw_verbose_limit == 0) + printf("unlimited logging\n"); + else + printf("logging limited to %d packets/entry by default\n", + fw_verbose_limit); +#endif +} + +static ip_fw_chk_t *old_chk_ptr; +static ip_fw_ctl_t *old_ctl_ptr; + +static int +ipfw_modevent(module_t mod, int type, void *unused) +{ + int s; + struct ip_fw_chain *fcp; + + switch (type) { + case MOD_LOAD: + s = splnet(); + + old_chk_ptr = ip_fw_chk_ptr; + old_ctl_ptr = ip_fw_ctl_ptr; + + ip_fw_init(); + splx(s); + return 0; + case MOD_UNLOAD: + s = splnet(); + ip_fw_chk_ptr = old_chk_ptr; + ip_fw_ctl_ptr = old_ctl_ptr; + remove_dyn_rule(NULL, 1 /* force delete */); + while ( (fcp = LIST_FIRST(&ip_fw_chain_head)) != NULL) { + LIST_REMOVE(fcp, next); +#ifdef DUMMYNET + dn_rule_delete(fcp); +#endif + free(fcp->rule, M_IPFW); + free(fcp, M_IPFW); + } + + splx(s); + printf("IP firewall unloaded\n"); + return 0; + default: + break; + } + return 0; +} + +static moduledata_t ipfwmod = { + "ipfw", + ipfw_modevent, + 0 +}; +DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY); |
