diff options
Diffstat (limited to 'c/src/libnetworking/netinet/ip_fw.c')
| -rw-r--r-- | c/src/libnetworking/netinet/ip_fw.c | 1069 |
1 files changed, 1069 insertions, 0 deletions
diff --git a/c/src/libnetworking/netinet/ip_fw.c b/c/src/libnetworking/netinet/ip_fw.c new file mode 100644 index 0000000000..aeb09b0bbe --- /dev/null +++ b/c/src/libnetworking/netinet/ip_fw.c @@ -0,0 +1,1069 @@ +/* + * Copyright (c) 1996 Alex Nash + * Copyright (c) 1993 Daniel Boulet + * Copyright (c) 1994 Ugen J.S.Antsilevich + * + * 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. + * + * $Id$ + */ + +/* + * Implement IP packet firewall + */ + +#ifndef IPFIREWALL_MODULE +#include "opt_ipfw.h" +#endif + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/queue.h> +#include <sys/kernel.h> +#include <sys/socket.h> +#include <sys/time.h> +#include <sys/sysctl.h> +#include <net/if.h> +#include <net/route.h> +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/ip_var.h> +#include <netinet/ip_icmp.h> +#include <netinet/ip_fw.h> +#include <netinet/tcp.h> +#include <netinet/tcp_timer.h> +#include <netinet/tcp_var.h> +#include <netinet/tcpip.h> +#include <netinet/udp.h> + +static int fw_debug = 1; +#ifdef IPFIREWALL_VERBOSE +static int fw_verbose = 1; +#else +static int fw_verbose = 0; +#endif +#ifdef IPFIREWALL_VERBOSE_LIMIT +static int fw_verbose_limit = IPFIREWALL_VERBOSE_LIMIT; +#else +static int fw_verbose_limit = 0; +#endif + +LIST_HEAD (ip_fw_head, ip_fw_chain) ip_fw_chain; + +#ifdef SYSCTL_NODE +SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall"); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, &fw_debug, 0, ""); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, &fw_verbose, 0, ""); +SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, &fw_verbose_limit, 0, ""); +#endif + +#define dprintf(a) if (!fw_debug); else printf a + +#define print_ip(a) printf("%ld.%ld.%ld.%ld",(ntohl(a.s_addr)>>24)&0xFF,\ + (ntohl(a.s_addr)>>16)&0xFF,\ + (ntohl(a.s_addr)>>8)&0xFF,\ + (ntohl(a.s_addr))&0xFF); + +#define dprint_ip(a) if (!fw_debug); else print_ip(a) + +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 mbuf *m)); +static struct ip_fw *check_ipfw_struct __P((struct ip_fw *m)); +static struct ip_fw *check_ipfw_mbuf __P((struct mbuf *fw)); +static int ipopts_match __P((struct ip *ip, struct ip_fw *f)); +static int port_match __P((u_short *portptr, int nports, u_short port, + int range_flag)); +static int tcpflg_match __P((struct tcphdr *tcp, struct ip_fw *f)); +static int icmptype_match __P((struct icmp * icmp, struct ip_fw * f)); +static void ipfw_report __P((struct ip_fw *f, struct ip *ip, + struct ifnet *rif, struct ifnet *oif)); + +#ifdef IPFIREWALL_MODULE +static ip_fw_chk_t *old_chk_ptr; +static ip_fw_ctl_t *old_ctl_ptr; +#endif + +static int ip_fw_chk __P((struct ip **pip, int hlen, + struct ifnet *oif, int ignport, struct mbuf **m)); +static int ip_fw_ctl __P((int stage, struct mbuf **mm)); + +static char err_prefix[] = "ip_fw_ctl:"; + +/* + * Returns 1 if the port is matched by the vector, 0 otherwise + */ +static inline int +port_match(u_short *portptr, int nports, u_short port, int range_flag) +{ + if (!nports) + return 1; + if (range_flag) { + if (portptr[0] <= port && port <= portptr[1]) { + return 1; + } + nports -= 2; + portptr += 2; + } + while (nports-- > 0) { + if (*portptr++ == port) { + return 1; + } + } + return 0; +} + +static int +tcpflg_match(struct tcphdr *tcp, struct ip_fw *f) +{ + u_char flg_set, flg_clr; + + if ((f->fw_tcpf & IP_FW_TCPF_ESTAB) && + (tcp->th_flags & (IP_FW_TCPF_RST | IP_FW_TCPF_ACK))) + return 1; + + flg_set = tcp->th_flags & f->fw_tcpf; + flg_clr = tcp->th_flags & f->fw_tcpnf; + + if (flg_set != f->fw_tcpf) + return 0; + if (flg_clr) + return 0; + + return 1; +} + +static int +icmptype_match(struct icmp *icmp, struct ip_fw *f) +{ + int type; + + if (!(f->fw_flg & IP_FW_F_ICMPBIT)) + return(1); + + type = icmp->icmp_type; + + /* check for matching type in the bitmap */ + if (type < IP_FW_ICMPTYPES_DIM * sizeof(unsigned) * 8 && + (f->fw_icmptypes[type / (sizeof(unsigned) * 8)] & + (1U << (type % (8 * sizeof(unsigned)))))) + return(1); + + return(0); /* no match */ +} + +static int +ipopts_match(struct ip *ip, struct ip_fw *f) +{ + register u_char *cp; + int opt, optlen, cnt; + u_char opts, nopts, nopts_sve; + + cp = (u_char *)(ip + 1); + cnt = (ip->ip_hl << 2) - sizeof (struct ip); + opts = f->fw_ipopt; + nopts = nopts_sve = f->fw_ipnopt; + + for (; cnt > 0; cnt -= optlen, cp += optlen) { + opt = cp[IPOPT_OPTVAL]; + if (opt == IPOPT_EOL) + break; + if (opt == IPOPT_NOP) + optlen = 1; + else { + optlen = cp[IPOPT_OLEN]; + if (optlen <= 0 || optlen > cnt) { + return 0; /*XXX*/ + } + } + switch (opt) { + + default: + break; + + case IPOPT_LSRR: + opts &= ~IP_FW_IPOPT_LSRR; + nopts &= ~IP_FW_IPOPT_LSRR; + break; + + case IPOPT_SSRR: + opts &= ~IP_FW_IPOPT_SSRR; + nopts &= ~IP_FW_IPOPT_SSRR; + break; + + case IPOPT_RR: + opts &= ~IP_FW_IPOPT_RR; + nopts &= ~IP_FW_IPOPT_RR; + break; + case IPOPT_TS: + opts &= ~IP_FW_IPOPT_TS; + nopts &= ~IP_FW_IPOPT_TS; + break; + } + if (opts == nopts) + break; + } + if (opts == 0 && nopts == nopts_sve) + return 1; + else + return 0; +} + +static inline int +iface_match(struct ifnet *ifp, union ip_fw_if *ifu, int byname) +{ + /* Check by name or by IP address */ + if (byname) { + /* Check unit number (-1 is wildcard) */ + if (ifu->fu_via_if.unit != -1 + && ifp->if_unit != ifu->fu_via_if.unit) + return(0); + /* Check name */ + if (strncmp(ifp->if_name, ifu->fu_via_if.name, FW_IFNLEN)) + return(0); + return(1); + } else if (ifu->fu_via_ip.s_addr != 0) { /* Zero == wildcard */ + struct ifaddr *ia; + + for (ia = ifp->if_addrlist; ia; ia = ia->ifa_next) { + if (ia->ifa_addr == NULL) + continue; + if (ia->ifa_addr->sa_family != AF_INET) + continue; + if (ifu->fu_via_ip.s_addr != ((struct sockaddr_in *) + (ia->ifa_addr))->sin_addr.s_addr) + continue; + return(1); + } + return(0); + } + return(1); +} + +static void +ipfw_report(struct ip_fw *f, struct ip *ip, + struct ifnet *rif, struct ifnet *oif) +{ + static int counter; + struct tcphdr *const tcp = (struct tcphdr *) ((u_long *) ip+ ip->ip_hl); + struct udphdr *const udp = (struct udphdr *) ((u_long *) ip+ ip->ip_hl); + struct icmp *const icmp = (struct icmp *) ((u_long *) ip + ip->ip_hl); + int count; + + count = f ? f->fw_pcnt : ++counter; + if (fw_verbose_limit != 0 && count > fw_verbose_limit) + return; + + /* Print command name */ + printf("ipfw: %d ", f ? f->fw_number : -1); + if (!f) + printf("Refuse"); + else + switch (f->fw_flg & IP_FW_F_COMMAND) { + case IP_FW_F_DENY: + printf("Deny"); + break; + case IP_FW_F_REJECT: + if (f->fw_reject_code == IP_FW_REJECT_RST) + printf("Reset"); + else + printf("Unreach"); + break; + case IP_FW_F_ACCEPT: + printf("Accept"); + break; + case IP_FW_F_COUNT: + printf("Count"); + break; + case IP_FW_F_DIVERT: + printf("Divert %d", f->fw_divert_port); + break; + case IP_FW_F_TEE: + printf("Tee %d", f->fw_divert_port); + break; + case IP_FW_F_SKIPTO: + printf("SkipTo %d", f->fw_skipto_rule); + break; + default: + printf("UNKNOWN"); + break; + } + printf(" "); + + switch (ip->ip_p) { + case IPPROTO_TCP: + printf("TCP "); + print_ip(ip->ip_src); + if ((ip->ip_off & IP_OFFMASK) == 0) + printf(":%d ", ntohs(tcp->th_sport)); + else + printf(" "); + print_ip(ip->ip_dst); + if ((ip->ip_off & IP_OFFMASK) == 0) + printf(":%d", ntohs(tcp->th_dport)); + break; + case IPPROTO_UDP: + printf("UDP "); + print_ip(ip->ip_src); + if ((ip->ip_off & IP_OFFMASK) == 0) + printf(":%d ", ntohs(udp->uh_sport)); + else + printf(" "); + print_ip(ip->ip_dst); + if ((ip->ip_off & IP_OFFMASK) == 0) + printf(":%d", ntohs(udp->uh_dport)); + break; + case IPPROTO_ICMP: + printf("ICMP:%u.%u ", icmp->icmp_type, icmp->icmp_code); + print_ip(ip->ip_src); + printf(" "); + print_ip(ip->ip_dst); + break; + default: + printf("P:%d ", ip->ip_p); + print_ip(ip->ip_src); + printf(" "); + print_ip(ip->ip_dst); + break; + } + if (oif) + printf(" out via %s%d", oif->if_name, oif->if_unit); + else if (rif) + printf(" in via %s%d", rif->if_name, rif->if_unit); + if ((ip->ip_off & IP_OFFMASK)) + printf(" Fragment = %d",ip->ip_off & IP_OFFMASK); + printf("\n"); + if (fw_verbose_limit != 0 && count == fw_verbose_limit) + printf("ipfw: limit reached on rule #%d\n", + f ? f->fw_number : -1); +} + +/* + * Parameters: + * + * ip Pointer to packet header (struct ip *) + * hlen Packet header length + * oif Outgoing interface, or NULL if packet is incoming + * ignport Ignore all divert/tee rules to this port (if non-zero) + * *m The packet; we set to NULL when/if we nuke it. + * + * Return value: + * + * 0 The packet is to be accepted and routed normally OR + * the packet was denied/rejected and has been dropped; + * in the latter case, *m is equal to NULL upon return. + * port Divert the packet to port. + */ + +static int +ip_fw_chk(struct ip **pip, int hlen, + struct ifnet *oif, int ignport, struct mbuf **m) +{ + struct ip_fw_chain *chain; + struct ip_fw *rule = NULL; + struct ip *ip = *pip; + struct ifnet *const rif = (*m)->m_pkthdr.rcvif; + u_short offset = (ip->ip_off & IP_OFFMASK); + u_short src_port, dst_port; + + /* + * Go down the chain, looking for enlightment + */ + for (chain=ip_fw_chain.lh_first; chain; chain = chain->chain.le_next) { + register struct ip_fw *const f = chain->rule; + + /* Check direction inbound */ + if (!oif && !(f->fw_flg & IP_FW_F_IN)) + continue; + + /* Check direction outbound */ + if (oif && !(f->fw_flg & IP_FW_F_OUT)) + continue; + + /* Fragments */ + if ((f->fw_flg & IP_FW_F_FRAG) && !(ip->ip_off & IP_OFFMASK)) + continue; + + /* If src-addr doesn't match, not this rule. */ + if (((f->fw_flg & IP_FW_F_INVSRC) != 0) ^ ((ip->ip_src.s_addr + & f->fw_smsk.s_addr) != f->fw_src.s_addr)) + continue; + + /* If dest-addr doesn't match, not this rule. */ + if (((f->fw_flg & IP_FW_F_INVDST) != 0) ^ ((ip->ip_dst.s_addr + & f->fw_dmsk.s_addr) != f->fw_dst.s_addr)) + continue; + + /* Interface check */ + if ((f->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) { + struct ifnet *const iface = oif ? oif : rif; + + /* Backwards compatibility hack for "via" */ + if (!iface || !iface_match(iface, + &f->fw_in_if, f->fw_flg & IP_FW_F_OIFNAME)) + continue; + } else { + /* Check receive interface */ + if ((f->fw_flg & IP_FW_F_IIFACE) + && (!rif || !iface_match(rif, + &f->fw_in_if, f->fw_flg & IP_FW_F_IIFNAME))) + continue; + /* Check outgoing interface */ + if ((f->fw_flg & IP_FW_F_OIFACE) + && (!oif || !iface_match(oif, + &f->fw_out_if, f->fw_flg & IP_FW_F_OIFNAME))) + continue; + } + + /* Check IP options */ + if (f->fw_ipopt != f->fw_ipnopt && !ipopts_match(ip, f)) + continue; + + /* Check protocol; if wildcard, match */ + if (f->fw_prot == IPPROTO_IP) + goto got_match; + + /* If different, don't match */ + if (ip->ip_p != f->fw_prot) + continue; + +#define PULLUP_TO(len) do { \ + if ((*m)->m_len < (len) \ + && (*m = m_pullup(*m, (len))) == 0) { \ + goto bogusfrag; \ + } \ + *pip = ip = mtod(*m, struct ip *); \ + offset = (ip->ip_off & IP_OFFMASK); \ + } while (0) + + /* Protocol specific checks */ + switch (ip->ip_p) { + case IPPROTO_TCP: + { + struct tcphdr *tcp; + + if (offset == 1) /* cf. RFC 1858 */ + goto bogusfrag; + if (offset != 0) { + /* + * TCP flags and ports aren't available in this + * packet -- if this rule specified either one, + * we consider the rule a non-match. + */ + if (f->fw_nports != 0 || + f->fw_tcpf != f->fw_tcpnf) + continue; + + break; + } + PULLUP_TO(hlen + 14); + tcp = (struct tcphdr *) ((u_long *)ip + ip->ip_hl); + if (f->fw_tcpf != f->fw_tcpnf && !tcpflg_match(tcp, f)) + continue; + src_port = ntohs(tcp->th_sport); + dst_port = ntohs(tcp->th_dport); + goto check_ports; + } + + case IPPROTO_UDP: + { + struct udphdr *udp; + + if (offset != 0) { + /* + * Port specification is unavailable -- if this + * rule specifies a port, we consider the rule + * a non-match. + */ + if (f->fw_nports != 0) + continue; + + break; + } + PULLUP_TO(hlen + 4); + udp = (struct udphdr *) ((u_long *)ip + ip->ip_hl); + src_port = ntohs(udp->uh_sport); + dst_port = ntohs(udp->uh_dport); +check_ports: + if (!port_match(&f->fw_pts[0], + IP_FW_GETNSRCP(f), src_port, + f->fw_flg & IP_FW_F_SRNG)) + continue; + if (!port_match(&f->fw_pts[IP_FW_GETNSRCP(f)], + IP_FW_GETNDSTP(f), dst_port, + f->fw_flg & IP_FW_F_DRNG)) + continue; + break; + } + + case IPPROTO_ICMP: + { + struct icmp *icmp; + + if (offset != 0) /* Type isn't valid */ + break; + PULLUP_TO(hlen + 2); + icmp = (struct icmp *) ((u_long *)ip + ip->ip_hl); + if (!icmptype_match(icmp, f)) + continue; + break; + } +#undef PULLUP_TO + +bogusfrag: + if (fw_verbose) + ipfw_report(NULL, ip, rif, oif); + goto dropit; + } + +got_match: + /* Ignore divert/tee rule if socket port is "ignport" */ + switch (f->fw_flg & IP_FW_F_COMMAND) { + case IP_FW_F_DIVERT: + case IP_FW_F_TEE: + if (f->fw_divert_port == ignport) + continue; /* ignore this rule */ + break; + } + + /* Update statistics */ + f->fw_pcnt += 1; + f->fw_bcnt += ip->ip_len; + f->timestamp = rtems_bsdnet_seconds_since_boot(); + + /* Log to console if desired */ + if ((f->fw_flg & IP_FW_F_PRN) && fw_verbose) + ipfw_report(f, ip, rif, oif); + + /* Take appropriate action */ + switch (f->fw_flg & IP_FW_F_COMMAND) { + case IP_FW_F_ACCEPT: + return(0); + case IP_FW_F_COUNT: + continue; + case IP_FW_F_DIVERT: + return(f->fw_divert_port); + case IP_FW_F_TEE: + /* + * XXX someday tee packet here, but beware that you + * can't use m_copym() or m_copypacket() because + * the divert input routine modifies the mbuf + * (and these routines only increment reference + * counts in the case of mbuf clusters), so need + * to write custom routine. + */ + continue; + case IP_FW_F_SKIPTO: +#ifdef DIAGNOSTIC + while (chain->chain.le_next + && chain->chain.le_next->rule->fw_number + < f->fw_skipto_rule) +#else + while (chain->chain.le_next->rule->fw_number + < f->fw_skipto_rule) +#endif + chain = chain->chain.le_next; + continue; + } + + /* Deny/reject this packet using this rule */ + rule = f; + break; + } + +#ifdef DIAGNOSTIC + /* Rule 65535 should always be there and should always match */ + if (!chain) + panic("ip_fw: chain"); +#endif + + /* + * At this point, we're going to drop the packet. + * Send a reject notice if all of the following are true: + * + * - The packet matched a reject rule + * - The packet is not an ICMP packet + * - 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 + && !((*m)->m_flags & (M_BCAST|M_MCAST)) + && !IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { + switch (rule->fw_reject_code) { + case IP_FW_REJECT_RST: + { + struct tcphdr *const tcp = + (struct tcphdr *) ((u_long *)ip + ip->ip_hl); + struct tcpiphdr ti, *const tip = (struct tcpiphdr *) ip; + + if (offset != 0 || (tcp->th_flags & TH_RST)) + break; + ti.ti_i = *((struct ipovly *) ip); + ti.ti_t = *tcp; + bcopy(&ti, ip, sizeof(ti)); + NTOHL(tip->ti_seq); + NTOHL(tip->ti_ack); + tip->ti_len = ip->ip_len - hlen - (tip->ti_off << 2); + if (tcp->th_flags & TH_ACK) { + tcp_respond(NULL, tip, *m, + (tcp_seq)0, ntohl(tcp->th_ack), TH_RST); + } else { + if (tcp->th_flags & TH_SYN) + tip->ti_len++; + tcp_respond(NULL, tip, *m, tip->ti_seq + + tip->ti_len, (tcp_seq)0, TH_RST|TH_ACK); + } + *m = NULL; + break; + } + default: /* Send an ICMP unreachable using code */ + icmp_error(*m, ICMP_UNREACH, + rule->fw_reject_code, 0L, 0); + *m = NULL; + break; + } + } + +dropit: + /* + * Finally, drop the packet. + */ + if (*m) { + m_freem(*m); + *m = NULL; + } + return(0); +} + +static int +add_entry(struct ip_fw_head *chainptr, struct ip_fw *frwl) +{ + struct ip_fw *ftmp = 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 = malloc(sizeof *ftmp, M_IPFW, M_DONTWAIT); + 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(struct ip_fw)); + ftmp->fw_in_if.fu_via_if.name[FW_IFNLEN - 1] = '\0'; + ftmp->fw_pcnt = 0L; + ftmp->fw_bcnt = 0L; + fwc->rule = ftmp; + + s = splnet(); + + if (!chainptr->lh_first) { + LIST_INSERT_HEAD(chainptr, fwc, chain); + splx(s); + return(0); + } else if (ftmp->fw_number == (u_short)-1) { + if (fwc) free(fwc, M_IPFW); + if (ftmp) free(ftmp, M_IPFW); + splx(s); + dprintf(("%s bad rule number\n", err_prefix)); + return (EINVAL); + } + + /* If entry number is 0, find highest numbered rule and add 100 */ + if (ftmp->fw_number == 0) { + for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next) { + if (fcp->rule->fw_number != (u_short)-1) + nbr = fcp->rule->fw_number; + else + break; + } + if (nbr < (u_short)-1 - 100) + nbr += 100; + ftmp->fw_number = nbr; + } + + /* Got a valid number; now insert it, keeping the list ordered */ + for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next) { + if (fcp->rule->fw_number > ftmp->fw_number) { + if (fcpl) { + LIST_INSERT_AFTER(fcpl, fwc, chain); + } else { + LIST_INSERT_HEAD(chainptr, fwc, chain); + } + break; + } else { + fcpl = fcp; + } + } + + splx(s); + return (0); +} + +static int +del_entry(struct ip_fw_head *chainptr, u_short number) +{ + struct ip_fw_chain *fcp; + int s; + + s = splnet(); + + fcp = chainptr->lh_first; + if (number != (u_short)-1) { + for (; fcp; fcp = fcp->chain.le_next) { + if (fcp->rule->fw_number == number) { + LIST_REMOVE(fcp, chain); + splx(s); + free(fcp->rule, M_IPFW); + free(fcp, M_IPFW); + return 0; + } + } + } + + splx(s); + return (EINVAL); +} + +static int +zero_entry(struct mbuf *m) +{ + struct ip_fw *frwl; + struct ip_fw_chain *fcp; + int s; + + if (m) { + if (m->m_len != sizeof(struct ip_fw)) + return(EINVAL); + frwl = mtod(m, struct ip_fw *); + } + else + frwl = NULL; + + /* + * 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. + */ + s = splnet(); + for (fcp = ip_fw_chain.lh_first; fcp; fcp = fcp->chain.le_next) + if (!frwl || frwl->fw_number == fcp->rule->fw_number) { + fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0; + fcp->rule->timestamp = 0; + } + splx(s); + + if (fw_verbose) { + if (frwl) + printf("ipfw: Entry %d cleared.\n", frwl->fw_number); + else + printf("ipfw: Accounting cleared.\n"); + } + + return(0); +} + +static struct ip_fw * +check_ipfw_mbuf(struct mbuf *m) +{ + /* Check length */ + if (m->m_len != sizeof(struct ip_fw)) { + dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len, + (int)sizeof(struct ip_fw))); + return (NULL); + } + return(check_ipfw_struct(mtod(m, struct ip_fw *))); +} + +static struct ip_fw * +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 (NULL); + } + /* 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 (NULL); + } + /* 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 (NULL); + } + /* 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 (NULL); + } + /* 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 (NULL); + } + 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 (NULL); + } + 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 (NULL); + } + /* + * 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(NULL); + } + + /* + * 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(NULL); + } + + 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(NULL); + } + if (frwl->fw_prot == IPPROTO_TCP && + frwl->fw_tcpf != frwl->fw_tcpnf) { + dprintf(("%s cannot mix 'frag' with TCP flags\n", err_prefix)); + return(NULL); + } + } + + /* 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(NULL); + } + break; + case IP_FW_F_DIVERT: /* Diverting to port zero is invalid */ + case IP_FW_F_TEE: + if (frwl->fw_divert_port == 0) { + dprintf(("%s can't divert to port 0\n", err_prefix)); + return (NULL); + } + break; + case IP_FW_F_DENY: + case IP_FW_F_ACCEPT: + case IP_FW_F_COUNT: + case IP_FW_F_SKIPTO: + break; + default: + dprintf(("%s invalid command\n", err_prefix)); + return(NULL); + } + + return frwl; +} + +static int +ip_fw_ctl(int stage, struct mbuf **mm) +{ + int error; + struct mbuf *m; + + if (stage == IP_FW_GET) { + struct ip_fw_chain *fcp = ip_fw_chain.lh_first; + *mm = m = m_get(M_WAIT, MT_SOOPTS); + for (; fcp; fcp = fcp->chain.le_next) { + memcpy(m->m_data, fcp->rule, sizeof *(fcp->rule)); + m->m_len = sizeof *(fcp->rule); + m->m_next = m_get(M_WAIT, MT_SOOPTS); + m = m->m_next; + m->m_len = 0; + } + return (0); + } + m = *mm; + /* only allow get calls if secure mode > 2 */ + if (securelevel > 2) { + if (m) (void)m_free(m); + return(EPERM); + } + if (stage == IP_FW_FLUSH) { + while (ip_fw_chain.lh_first != NULL && + ip_fw_chain.lh_first->rule->fw_number != (u_short)-1) { + struct ip_fw_chain *fcp = ip_fw_chain.lh_first; + int s = splnet(); + LIST_REMOVE(ip_fw_chain.lh_first, chain); + splx(s); + free(fcp->rule, M_IPFW); + free(fcp, M_IPFW); + } + if (m) (void)m_free(m); + return (0); + } + if (stage == IP_FW_ZERO) { + error = zero_entry(m); + if (m) (void)m_free(m); + return (error); + } + if (m == NULL) { + printf("%s NULL mbuf ptr\n", err_prefix); + return (EINVAL); + } + + if (stage == IP_FW_ADD) { + struct ip_fw *frwl = check_ipfw_mbuf(m); + + if (!frwl) + error = EINVAL; + else + error = add_entry(&ip_fw_chain, frwl); + if (m) (void)m_free(m); + return error; + } + if (stage == IP_FW_DEL) { + if (m->m_len != sizeof(struct ip_fw)) { + dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len, + (int)sizeof(struct ip_fw))); + error = EINVAL; + } else if (mtod(m, struct ip_fw *)->fw_number == (u_short)-1) { + dprintf(("%s can't delete rule 65535\n", err_prefix)); + error = EINVAL; + } else + error = del_entry(&ip_fw_chain, + mtod(m, struct ip_fw *)->fw_number); + if (m) (void)m_free(m); + return error; + } + + dprintf(("%s unknown request %d\n", err_prefix, stage)); + if (m) (void)m_free(m); + return (EINVAL); +} + +void +ip_fw_init(void) +{ + struct ip_fw default_rule; + + ip_fw_chk_ptr = ip_fw_chk; + ip_fw_ctl_ptr = ip_fw_ctl; + LIST_INIT(&ip_fw_chain); + + bzero(&default_rule, sizeof default_rule); + default_rule.fw_prot = IPPROTO_IP; + default_rule.fw_number = (u_short)-1; +#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) == NULL || + add_entry(&ip_fw_chain, &default_rule)) + panic(__FUNCTION__); + + printf("IP packet filtering initialized, " +#ifdef IPDIVERT + "divert enabled, "); +#else + "divert disabled, "); +#endif +#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT + printf("default to accept, "); +#endif +#ifndef IPFIREWALL_VERBOSE + printf("logging disabled\n"); +#else + if (fw_verbose_limit == 0) + printf("unlimited logging\n"); + else + printf("logging limited to %d packets/entry\n", + fw_verbose_limit); +#endif +} + +#ifdef IPFIREWALL_MODULE + +#include <sys/exec.h> +#include <sys/sysent.h> +#include <sys/lkm.h> + +MOD_MISC(ipfw); + +static int +ipfw_load(struct lkm_table *lkmtp, int cmd) +{ + int s=splnet(); + + old_chk_ptr = ip_fw_chk_ptr; + old_ctl_ptr = ip_fw_ctl_ptr; + + ip_fw_init(); + splx(s); + return 0; +} + +static int +ipfw_unload(struct lkm_table *lkmtp, int cmd) +{ + int s=splnet(); + + ip_fw_chk_ptr = old_chk_ptr; + ip_fw_ctl_ptr = old_ctl_ptr; + + while (ip_fw_chain.lh_first != NULL) { + struct ip_fw_chain *fcp = ip_fw_chain.lh_first; + LIST_REMOVE(ip_fw_chain.lh_first, chain); + free(fcp->rule, M_IPFW); + free(fcp, M_IPFW); + } + + splx(s); + printf("IP firewall unloaded\n"); + return 0; +} + +int +ipfw_mod(struct lkm_table *lkmtp, int cmd, int ver) +{ + DISPATCH(lkmtp, cmd, ver, ipfw_load, ipfw_unload, lkm_nullcmd); +} +#endif |