/*- * Copyright (c) 2004 Andre Oppermann, Internet Business Solutions AG * All rights reserved. * * 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. */ #include __FBSDID("$FreeBSD: stable/11/sys/netpfil/ipfw/ip_fw_pfil.c 346210 2019-04-14 12:34:30Z ae $"); #include "opt_ipfw.h" #include "opt_inet.h" #include "opt_inet6.h" #ifndef INET #error IPFIREWALL requires INET. #endif /* INET */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #include #include #endif #include #include #include static VNET_DEFINE(int, fw_enable) = 1; #define V_fw_enable VNET(fw_enable) #ifdef INET6 static VNET_DEFINE(int, fw6_enable) = 1; #define V_fw6_enable VNET(fw6_enable) #endif static VNET_DEFINE(int, fwlink_enable) = 0; #define V_fwlink_enable VNET(fwlink_enable) int ipfw_chg_hook(SYSCTL_HANDLER_ARGS); /* Forward declarations. */ static int ipfw_divert(struct mbuf **, int, struct ipfw_rule_ref *, int); int ipfw_check_packet(void *, struct mbuf **, struct ifnet *, int, struct inpcb *); int ipfw_check_frame(void *, struct mbuf **, struct ifnet *, int, struct inpcb *); #ifdef SYSCTL_NODE SYSBEGIN(f1) SYSCTL_DECL(_net_inet_ip_fw); SYSCTL_PROC(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3, &VNET_NAME(fw_enable), 0, ipfw_chg_hook, "I", "Enable ipfw"); #ifdef INET6 SYSCTL_DECL(_net_inet6_ip6_fw); SYSCTL_PROC(_net_inet6_ip6_fw, OID_AUTO, enable, CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3, &VNET_NAME(fw6_enable), 0, ipfw_chg_hook, "I", "Enable ipfw+6"); #endif /* INET6 */ SYSCTL_DECL(_net_link_ether); SYSCTL_PROC(_net_link_ether, OID_AUTO, ipfw, CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3, &VNET_NAME(fwlink_enable), 0, ipfw_chg_hook, "I", "Pass ether pkts through firewall"); SYSEND #endif /* SYSCTL_NODE */ /* * The pfilter hook to pass packets to ipfw_chk and then to * dummynet, divert, netgraph or other modules. * The packet may be consumed. */ int ipfw_check_packet(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir, struct inpcb *inp) { struct ip_fw_args args; struct m_tag *tag; int ipfw, ret; /* convert dir to IPFW values */ dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT; args.flags = 0; again: /* * extract and remove the tag if present. If we are left * with onepass, optimize the outgoing path. */ tag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL); if (tag != NULL) { args.rule = *((struct ipfw_rule_ref *)(tag+1)); m_tag_delete(*m0, tag); if (args.rule.info & IPFW_ONEPASS) return (0); args.flags |= IPFW_ARGS_REF; } args.m = *m0; args.oif = dir == DIR_OUT ? ifp : NULL; args.inp = inp; ipfw = ipfw_chk(&args); *m0 = args.m; KASSERT(*m0 != NULL || ipfw == IP_FW_DENY || ipfw == IP_FW_NAT64, ("%s: m0 is NULL", __func__)); /* breaking out of the switch means drop */ switch (ipfw) { case IP_FW_PASS: /* next_hop may be set by ipfw_chk */ if ((args.flags & (IPFW_ARGS_NH4 | IPFW_ARGS_NH4PTR | IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)) == 0) { ret = 0; break; } #if (!defined(INET6) && !defined(INET)) ret = EACCES; #else { void *psa; size_t len; #ifdef INET if (args.flags & (IPFW_ARGS_NH4 | IPFW_ARGS_NH4PTR)) { MPASS((args.flags & (IPFW_ARGS_NH4 | IPFW_ARGS_NH4PTR)) != (IPFW_ARGS_NH4 | IPFW_ARGS_NH4PTR)); MPASS((args.flags & (IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)) == 0); len = sizeof(struct sockaddr_in); psa = (args.flags & IPFW_ARGS_NH4) ? &args.hopstore : args.next_hop; if (in_localip(satosin(psa)->sin_addr)) (*m0)->m_flags |= M_FASTFWD_OURS; (*m0)->m_flags |= M_IP_NEXTHOP; } #endif /* INET */ #ifdef INET6 if (args.flags & (IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)) { MPASS((args.flags & (IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)) != (IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)); MPASS((args.flags & (IPFW_ARGS_NH4 | IPFW_ARGS_NH4PTR)) == 0); len = sizeof(struct sockaddr_in6); psa = args.next_hop6; (*m0)->m_flags |= M_IP6_NEXTHOP; } #endif /* INET6 */ /* * Incoming packets should not be tagged so we do not * m_tag_find. Outgoing packets may be tagged, so we * reuse the tag if present. */ tag = (dir == DIR_IN) ? NULL : m_tag_find(*m0, PACKET_TAG_IPFORWARD, NULL); if (tag != NULL) { m_tag_unlink(*m0, tag); } else { tag = m_tag_get(PACKET_TAG_IPFORWARD, len, M_NOWAIT); if (tag == NULL) { ret = EACCES; break; /* i.e. drop */ } } if ((args.flags & IPFW_ARGS_NH6) == 0) bcopy(psa, tag + 1, len); m_tag_prepend(*m0, tag); ret = 0; #ifdef INET6 /* IPv6 next hop needs additional handling */ if (args.flags & (IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)) { struct sockaddr_in6 *sa6; sa6 = satosin6(tag + 1); if (args.flags & IPFW_ARGS_NH6) { sa6->sin6_family = AF_INET6; sa6->sin6_len = sizeof(*sa6); sa6->sin6_addr = args.hopstore6.sin6_addr; sa6->sin6_port = args.hopstore6.sin6_port; sa6->sin6_scope_id = args.hopstore6.sin6_scope_id; } /* * If nh6 address is link-local we should convert * it to kernel internal form before doing any * comparisons. */ if (sa6_embedscope(sa6, V_ip6_use_defzone) != 0) { ret = EACCES; break; } if (in6_localip(&sa6->sin6_addr)) (*m0)->m_flags |= M_FASTFWD_OURS; } #endif /* INET6 */ } #endif /* INET || INET6 */ break; case IP_FW_DENY: ret = EACCES; break; /* i.e. drop */ case IP_FW_DUMMYNET: ret = EACCES; if (ip_dn_io_ptr == NULL) break; /* i.e. drop */ MPASS(args.flags & IPFW_ARGS_REF); if (mtod(*m0, struct ip *)->ip_v == 4) ret = ip_dn_io_ptr(m0, dir, &args); else if (mtod(*m0, struct ip *)->ip_v == 6) ret = ip_dn_io_ptr(m0, dir | PROTO_IPV6, &args); else break; /* drop it */ /* * XXX should read the return value. * dummynet normally eats the packet and sets *m0=NULL * unless the packet can be sent immediately. In this * case args is updated and we should re-run the * check without clearing args. */ if (*m0 != NULL) goto again; break; case IP_FW_TEE: case IP_FW_DIVERT: if (ip_divert_ptr == NULL) { ret = EACCES; break; /* i.e. drop */ } MPASS(args.flags & IPFW_ARGS_REF); ret = ipfw_divert(m0, dir, &args.rule, (ipfw == IP_FW_TEE) ? 1 : 0); /* continue processing for the original packet (tee). */ if (*m0) goto again; break; case IP_FW_NGTEE: case IP_FW_NETGRAPH: if (ng_ipfw_input_p == NULL) { ret = EACCES; break; /* i.e. drop */ } MPASS(args.flags & IPFW_ARGS_REF); ret = ng_ipfw_input_p(m0, dir, &args, (ipfw == IP_FW_NGTEE) ? 1 : 0); if (ipfw == IP_FW_NGTEE) /* ignore errors for NGTEE */ goto again; /* continue with packet */ break; case IP_FW_NAT: /* honor one-pass in case of successful nat */ if (V_fw_one_pass) { ret = 0; break; } goto again; case IP_FW_REASS: goto again; /* continue with packet */ case IP_FW_NAT64: ret = 0; break; default: KASSERT(0, ("%s: unknown retval", __func__)); } if (ret != 0) { if (*m0) FREE_PKT(*m0); *m0 = NULL; } return (ret); } /* * ipfw processing for ethernet packets (in and out). */ int ipfw_check_frame(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir, struct inpcb *inp) { struct ip_fw_args args; struct ether_header save_eh; struct ether_header *eh; struct m_tag *mtag; struct mbuf *m; int i, ret; args.flags = IPFW_ARGS_ETHER; again: /* fetch start point from rule, if any. remove the tag if present. */ mtag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL); if (mtag != NULL) { args.rule = *((struct ipfw_rule_ref *)(mtag+1)); m_tag_delete(*m0, mtag); if (args.rule.info & IPFW_ONEPASS) return (0); args.flags |= IPFW_ARGS_REF; } /* I need some amt of data to be contiguous */ m = *m0; i = min(m->m_pkthdr.len, max_protohdr); if (m->m_len < i) { m = m_pullup(m, i); if (m == NULL) { *m0 = m; return (0); } } eh = mtod(m, struct ether_header *); save_eh = *eh; /* save copy for restore below */ m_adj(m, ETHER_HDR_LEN); /* strip ethernet header */ args.m = m; /* the packet we are looking at */ args.oif = dir == PFIL_OUT ? ifp: NULL; /* destination, if any */ args.eh = &save_eh; /* MAC header for bridged/MAC packets */ args.inp = inp; /* used by ipfw uid/gid/jail rules */ i = ipfw_chk(&args); m = args.m; if (m != NULL) { /* * Restore Ethernet header, as needed, in case the * mbuf chain was replaced by ipfw. */ M_PREPEND(m, ETHER_HDR_LEN, M_NOWAIT); if (m == NULL) { *m0 = NULL; return (0); } if (eh != mtod(m, struct ether_header *)) bcopy(&save_eh, mtod(m, struct ether_header *), ETHER_HDR_LEN); } *m0 = m; ret = 0; /* Check result of ipfw_chk() */ switch (i) { case IP_FW_PASS: break; case IP_FW_DENY: ret = EACCES; break; /* i.e. drop */ case IP_FW_DUMMYNET: ret = EACCES; if (ip_dn_io_ptr == NULL) break; /* i.e. drop */ *m0 = NULL; dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT; MPASS(args.flags & IPFW_ARGS_REF); ip_dn_io_ptr(&m, dir | PROTO_LAYER2, &args); return 0; case IP_FW_NGTEE: case IP_FW_NETGRAPH: if (ng_ipfw_input_p == NULL) { ret = EACCES; break; /* i.e. drop */ } MPASS(args.flags & IPFW_ARGS_REF); ret = ng_ipfw_input_p(m0, (dir == PFIL_IN) ? DIR_IN : DIR_OUT, &args, (i == IP_FW_NGTEE) ? 1 : 0); if (i == IP_FW_NGTEE) /* ignore errors for NGTEE */ goto again; /* continue with packet */ break; default: KASSERT(0, ("%s: unknown retval", __func__)); } if (ret != 0) { if (*m0) FREE_PKT(*m0); *m0 = NULL; } return (ret); } /* do the divert, return 1 on error 0 on success */ static int ipfw_divert(struct mbuf **m0, int incoming, struct ipfw_rule_ref *rule, int tee) { /* * ipfw_chk() has already tagged the packet with the divert tag. * If tee is set, copy packet and return original. * If not tee, consume packet and send it to divert socket. */ struct mbuf *clone; struct ip *ip = mtod(*m0, struct ip *); struct m_tag *tag; /* Cloning needed for tee? */ if (tee == 0) { clone = *m0; /* use the original mbuf */ *m0 = NULL; } else { clone = m_dup(*m0, M_NOWAIT); /* If we cannot duplicate the mbuf, we sacrifice the divert * chain and continue with the tee-ed packet. */ if (clone == NULL) return 1; } /* * Divert listeners can normally handle non-fragmented packets, * but we can only reass in the non-tee case. * This means that listeners on a tee rule may get fragments, * and have to live with that. * Note that we now have the 'reass' ipfw option so if we care * we can do it before a 'tee'. */ if (!tee) switch (ip->ip_v) { case IPVERSION: if (ntohs(ip->ip_off) & (IP_MF | IP_OFFMASK)) { int hlen; struct mbuf *reass; reass = ip_reass(clone); /* Reassemble packet. */ if (reass == NULL) return 0; /* not an error */ /* if reass = NULL then it was consumed by ip_reass */ /* * IP header checksum fixup after reassembly and leave header * in network byte order. */ ip = mtod(reass, struct ip *); hlen = ip->ip_hl << 2; ip->ip_sum = 0; if (hlen == sizeof(struct ip)) ip->ip_sum = in_cksum_hdr(ip); else ip->ip_sum = in_cksum(reass, hlen); clone = reass; } break; #ifdef INET6 case IPV6_VERSION >> 4: { struct ip6_hdr *const ip6 = mtod(clone, struct ip6_hdr *); if (ip6->ip6_nxt == IPPROTO_FRAGMENT) { int nxt, off; off = sizeof(struct ip6_hdr); nxt = frag6_input(&clone, &off, 0); if (nxt == IPPROTO_DONE) return (0); } break; } #endif } /* attach a tag to the packet with the reinject info */ tag = m_tag_alloc(MTAG_IPFW_RULE, 0, sizeof(struct ipfw_rule_ref), M_NOWAIT); if (tag == NULL) { FREE_PKT(clone); return 1; } *((struct ipfw_rule_ref *)(tag+1)) = *rule; m_tag_prepend(clone, tag); /* Do the dirty job... */ ip_divert_ptr(clone, incoming); return 0; } /* * attach or detach hooks for a given protocol family */ static int ipfw_hook(int onoff, int pf) { struct pfil_head *pfh; pfil_func_t hook_func; pfh = pfil_head_get(PFIL_TYPE_AF, pf); if (pfh == NULL) return ENOENT; hook_func = (pf == AF_LINK) ? ipfw_check_frame : ipfw_check_packet; (void) (onoff ? pfil_add_hook : pfil_remove_hook) (hook_func, NULL, PFIL_IN | PFIL_OUT | PFIL_WAITOK, pfh); return 0; } int ipfw_attach_hooks(int arg) { int error = 0; if (arg == 0) /* detach */ ipfw_hook(0, AF_INET); else if (V_fw_enable && ipfw_hook(1, AF_INET) != 0) { error = ENOENT; /* see ip_fw_pfil.c::ipfw_hook() */ printf("ipfw_hook() error\n"); } #ifdef INET6 if (arg == 0) /* detach */ ipfw_hook(0, AF_INET6); else if (V_fw6_enable && ipfw_hook(1, AF_INET6) != 0) { error = ENOENT; printf("ipfw6_hook() error\n"); } #endif if (arg == 0) /* detach */ ipfw_hook(0, AF_LINK); else if (V_fwlink_enable && ipfw_hook(1, AF_LINK) != 0) { error = ENOENT; printf("ipfw_link_hook() error\n"); } return error; } int ipfw_chg_hook(SYSCTL_HANDLER_ARGS) { int newval; int error; int af; if (arg1 == &V_fw_enable) af = AF_INET; #ifdef INET6 else if (arg1 == &V_fw6_enable) af = AF_INET6; #endif else if (arg1 == &V_fwlink_enable) af = AF_LINK; else return (EINVAL); newval = *(int *)arg1; /* Handle sysctl change */ error = sysctl_handle_int(oidp, &newval, 0, req); if (error) return (error); /* Formalize new value */ newval = (newval) ? 1 : 0; if (*(int *)arg1 == newval) return (0); error = ipfw_hook(newval, af); if (error) return (error); *(int *)arg1 = newval; return (0); } /* end of file */