/*- * Copyright (c) 2008 Paolo Pisati * 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("$FreeBSD$"); #include #include #include #include #include #include #include #include #define IPFW_INTERNAL /* Access to protected data structures in ip_fw.h. */ #include #include #include #include #include #include #include #include #include #include #include /* XXX for in_cksum */ static VNET_DEFINE(eventhandler_tag, ifaddr_event_tag); #define V_ifaddr_event_tag VNET(ifaddr_event_tag) static void ifaddr_change(void *arg __unused, struct ifnet *ifp) { struct cfg_nat *ptr; struct ifaddr *ifa; struct ip_fw_chain *chain; chain = &V_layer3_chain; IPFW_WLOCK(chain); /* Check every nat entry... */ LIST_FOREACH(ptr, &chain->nat, _next) { /* ...using nic 'ifp->if_xname' as dynamic alias address. */ if (strncmp(ptr->if_name, ifp->if_xname, IF_NAMESIZE) != 0) continue; if_addr_rlock(ifp); TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { if (ifa->ifa_addr == NULL) continue; if (ifa->ifa_addr->sa_family != AF_INET) continue; ptr->ip = ((struct sockaddr_in *) (ifa->ifa_addr))->sin_addr; LibAliasSetAddress(ptr->lib, ptr->ip); } if_addr_runlock(ifp); } IPFW_WUNLOCK(chain); } /* * delete the pointers for nat entry ix, or all of them if ix < 0 */ static void flush_nat_ptrs(struct ip_fw_chain *chain, const int ix) { int i; ipfw_insn_nat *cmd; IPFW_WLOCK_ASSERT(chain); for (i = 0; i < chain->n_rules; i++) { cmd = (ipfw_insn_nat *)ACTION_PTR(chain->map[i]); /* XXX skip log and the like ? */ if (cmd->o.opcode == O_NAT && cmd->nat != NULL && (ix < 0 || cmd->nat->id == ix)) cmd->nat = NULL; } } static void del_redir_spool_cfg(struct cfg_nat *n, struct redir_chain *head) { struct cfg_redir *r, *tmp_r; struct cfg_spool *s, *tmp_s; int i, num; LIST_FOREACH_SAFE(r, head, _next, tmp_r) { num = 1; /* Number of alias_link to delete. */ switch (r->mode) { case REDIR_PORT: num = r->pport_cnt; /* FALLTHROUGH */ case REDIR_ADDR: case REDIR_PROTO: /* Delete all libalias redirect entry. */ for (i = 0; i < num; i++) LibAliasRedirectDelete(n->lib, r->alink[i]); /* Del spool cfg if any. */ LIST_FOREACH_SAFE(s, &r->spool_chain, _next, tmp_s) { LIST_REMOVE(s, _next); free(s, M_IPFW); } free(r->alink, M_IPFW); LIST_REMOVE(r, _next); free(r, M_IPFW); break; default: printf("unknown redirect mode: %u\n", r->mode); /* XXX - panic?!?!? */ break; } } } static void add_redir_spool_cfg(char *buf, struct cfg_nat *ptr) { struct cfg_redir *r, *ser_r; struct cfg_spool *s, *ser_s; int cnt, off, i; for (cnt = 0, off = 0; cnt < ptr->redir_cnt; cnt++) { ser_r = (struct cfg_redir *)&buf[off]; r = malloc(SOF_REDIR, M_IPFW, M_WAITOK | M_ZERO); memcpy(r, ser_r, SOF_REDIR); LIST_INIT(&r->spool_chain); off += SOF_REDIR; r->alink = malloc(sizeof(struct alias_link *) * r->pport_cnt, M_IPFW, M_WAITOK | M_ZERO); switch (r->mode) { case REDIR_ADDR: r->alink[0] = LibAliasRedirectAddr(ptr->lib, r->laddr, r->paddr); break; case REDIR_PORT: for (i = 0 ; i < r->pport_cnt; i++) { /* If remotePort is all ports, set it to 0. */ u_short remotePortCopy = r->rport + i; if (r->rport_cnt == 1 && r->rport == 0) remotePortCopy = 0; r->alink[i] = LibAliasRedirectPort(ptr->lib, r->laddr, htons(r->lport + i), r->raddr, htons(remotePortCopy), r->paddr, htons(r->pport + i), r->proto); if (r->alink[i] == NULL) { r->alink[0] = NULL; break; } } break; case REDIR_PROTO: r->alink[0] = LibAliasRedirectProto(ptr->lib ,r->laddr, r->raddr, r->paddr, r->proto); break; default: printf("unknown redirect mode: %u\n", r->mode); break; } /* XXX perhaps return an error instead of panic ? */ if (r->alink[0] == NULL) panic("LibAliasRedirect* returned NULL"); /* LSNAT handling. */ for (i = 0; i < r->spool_cnt; i++) { ser_s = (struct cfg_spool *)&buf[off]; s = malloc(SOF_REDIR, M_IPFW, M_WAITOK | M_ZERO); memcpy(s, ser_s, SOF_SPOOL); LibAliasAddServer(ptr->lib, r->alink[0], s->addr, htons(s->port)); off += SOF_SPOOL; /* Hook spool entry. */ LIST_INSERT_HEAD(&r->spool_chain, s, _next); } /* And finally hook this redir entry. */ LIST_INSERT_HEAD(&ptr->redir_chain, r, _next); } } static int ipfw_nat(struct ip_fw_args *args, struct cfg_nat *t, struct mbuf *m) { struct mbuf *mcl; struct ip *ip; /* XXX - libalias duct tape */ int ldt, retval, found; struct ip_fw_chain *chain; char *c; ldt = 0; retval = 0; mcl = m_megapullup(m, m->m_pkthdr.len); if (mcl == NULL) { args->m = NULL; return (IP_FW_DENY); } ip = mtod(mcl, struct ip *); /* * XXX - Libalias checksum offload 'duct tape': * * locally generated packets have only pseudo-header checksum * calculated and libalias will break it[1], so mark them for * later fix. Moreover there are cases when libalias modifies * tcp packet data[2], mark them for later fix too. * * [1] libalias was never meant to run in kernel, so it does * not have any knowledge about checksum offloading, and * expects a packet with a full internet checksum. * Unfortunately, packets generated locally will have just the * pseudo header calculated, and when libalias tries to adjust * the checksum it will actually compute a wrong value. * * [2] when libalias modifies tcp's data content, full TCP * checksum has to be recomputed: the problem is that * libalias does not have any idea about checksum offloading. * To work around this, we do not do checksumming in LibAlias, * but only mark the packets in th_x2 field. If we receive a * marked packet, we calculate correct checksum for it * aware of offloading. Why such a terrible hack instead of * recalculating checksum for each packet? * Because the previous checksum was not checked! * Recalculating checksums for EVERY packet will hide ALL * transmission errors. Yes, marked packets still suffer from * this problem. But, sigh, natd(8) has this problem, too. * * TODO: -make libalias mbuf aware (so * it can handle delayed checksum and tso) */ if (mcl->m_pkthdr.rcvif == NULL && mcl->m_pkthdr.csum_flags & CSUM_DELAY_DATA) ldt = 1; c = mtod(mcl, char *); /* Check if this is 'global' instance */ if (t == NULL) { if (args->oif == NULL) { /* Wrong direction, skip processing */ args->m = mcl; return (IP_FW_NAT); } found = 0; chain = &V_layer3_chain; IPFW_RLOCK(chain); /* Check every nat entry... */ LIST_FOREACH(t, &chain->nat, _next) { if ((t->mode & PKT_ALIAS_SKIP_GLOBAL) != 0) continue; retval = LibAliasOutTry(t->lib, c, mcl->m_len + M_TRAILINGSPACE(mcl), 0); if (retval == PKT_ALIAS_OK) { /* Nat instance recognises state */ found = 1; break; } } IPFW_RUNLOCK(chain); if (found != 1) { /* No instance found, return ignore */ args->m = mcl; return (IP_FW_NAT); } } else { if (args->oif == NULL) retval = LibAliasIn(t->lib, c, mcl->m_len + M_TRAILINGSPACE(mcl)); else retval = LibAliasOut(t->lib, c, mcl->m_len + M_TRAILINGSPACE(mcl)); } /* * We drop packet when: * 1. libalias returns PKT_ALIAS_ERROR; * 2. For incoming packets: * a) for unresolved fragments; * b) libalias returns PKT_ALIAS_IGNORED and * PKT_ALIAS_DENY_INCOMING flag is set. */ if (retval == PKT_ALIAS_ERROR || (args->oif == NULL && (retval == PKT_ALIAS_UNRESOLVED_FRAGMENT || (retval == PKT_ALIAS_IGNORED && (t->mode & PKT_ALIAS_DENY_INCOMING) != 0)))) { /* XXX - should i add some logging? */ m_free(mcl); args->m = NULL; return (IP_FW_DENY); } if (retval == PKT_ALIAS_RESPOND) m->m_flags |= M_SKIP_FIREWALL; mcl->m_pkthdr.len = mcl->m_len = ntohs(ip->ip_len); /* * XXX - libalias checksum offload * 'duct tape' (see above) */ if ((ip->ip_off & htons(IP_OFFMASK)) == 0 && ip->ip_p == IPPROTO_TCP) { struct tcphdr *th; th = (struct tcphdr *)(ip + 1); if (th->th_x2) ldt = 1; } if (ldt) { struct tcphdr *th; struct udphdr *uh; u_short cksum; ip->ip_len = ntohs(ip->ip_len); cksum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, htons(ip->ip_p + ip->ip_len - (ip->ip_hl << 2))); switch (ip->ip_p) { case IPPROTO_TCP: th = (struct tcphdr *)(ip + 1); /* * Maybe it was set in * libalias... */ th->th_x2 = 0; th->th_sum = cksum; mcl->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); break; case IPPROTO_UDP: uh = (struct udphdr *)(ip + 1); uh->uh_sum = cksum; mcl->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); break; } /* No hw checksum offloading: do it ourselves */ if ((mcl->m_pkthdr.csum_flags & CSUM_DELAY_DATA) == 0) { in_delayed_cksum(mcl); mcl->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA; } ip->ip_len = htons(ip->ip_len); } args->m = mcl; return (IP_FW_NAT); } static struct cfg_nat * lookup_nat(struct nat_list *l, int nat_id) { struct cfg_nat *res; LIST_FOREACH(res, l, _next) { if (res->id == nat_id) break; } return res; } static int ipfw_nat_cfg(struct sockopt *sopt) { struct cfg_nat *cfg, *ptr; char *buf; struct ip_fw_chain *chain = &V_layer3_chain; size_t len; int gencnt, error = 0; len = sopt->sopt_valsize; buf = malloc(len, M_TEMP, M_WAITOK | M_ZERO); if ((error = sooptcopyin(sopt, buf, len, sizeof(struct cfg_nat))) != 0) goto out; cfg = (struct cfg_nat *)buf; if (cfg->id < 0) { error = EINVAL; goto out; } /* * Find/create nat rule. */ IPFW_WLOCK(chain); gencnt = chain->gencnt; ptr = lookup_nat(&chain->nat, cfg->id); if (ptr == NULL) { IPFW_WUNLOCK(chain); /* New rule: allocate and init new instance. */ ptr = malloc(sizeof(struct cfg_nat), M_IPFW, M_WAITOK | M_ZERO); ptr->lib = LibAliasInit(NULL); LIST_INIT(&ptr->redir_chain); } else { /* Entry already present: temporarily unhook it. */ LIST_REMOVE(ptr, _next); flush_nat_ptrs(chain, cfg->id); IPFW_WUNLOCK(chain); } /* * Basic nat configuration. */ ptr->id = cfg->id; /* * XXX - what if this rule doesn't nat any ip and just * redirect? * do we set aliasaddress to 0.0.0.0? */ ptr->ip = cfg->ip; ptr->redir_cnt = cfg->redir_cnt; ptr->mode = cfg->mode; LibAliasSetMode(ptr->lib, cfg->mode, cfg->mode); LibAliasSetAddress(ptr->lib, ptr->ip); memcpy(ptr->if_name, cfg->if_name, IF_NAMESIZE); /* * Redir and LSNAT configuration. */ /* Delete old cfgs. */ del_redir_spool_cfg(ptr, &ptr->redir_chain); /* Add new entries. */ add_redir_spool_cfg(&buf[(sizeof(struct cfg_nat))], ptr); IPFW_WLOCK(chain); /* Extra check to avoid race with another ipfw_nat_cfg() */ if (gencnt != chain->gencnt && ((cfg = lookup_nat(&chain->nat, ptr->id)) != NULL)) LIST_REMOVE(cfg, _next); LIST_INSERT_HEAD(&chain->nat, ptr, _next); chain->gencnt++; IPFW_WUNLOCK(chain); out: free(buf, M_TEMP); return (error); } static int ipfw_nat_del(struct sockopt *sopt) { struct cfg_nat *ptr; struct ip_fw_chain *chain = &V_layer3_chain; int i; sooptcopyin(sopt, &i, sizeof i, sizeof i); /* XXX validate i */ IPFW_WLOCK(chain); ptr = lookup_nat(&chain->nat, i); if (ptr == NULL) { IPFW_WUNLOCK(chain); return (EINVAL); } LIST_REMOVE(ptr, _next); flush_nat_ptrs(chain, i); IPFW_WUNLOCK(chain); del_redir_spool_cfg(ptr, &ptr->redir_chain); LibAliasUninit(ptr->lib); free(ptr, M_IPFW); return (0); } static int ipfw_nat_get_cfg(struct sockopt *sopt) { struct ip_fw_chain *chain = &V_layer3_chain; struct cfg_nat *n; struct cfg_redir *r; struct cfg_spool *s; char *data; int gencnt, nat_cnt, len, error; nat_cnt = 0; len = sizeof(nat_cnt); IPFW_RLOCK(chain); retry: gencnt = chain->gencnt; /* Estimate memory amount */ LIST_FOREACH(n, &chain->nat, _next) { nat_cnt++; len += sizeof(struct cfg_nat); LIST_FOREACH(r, &n->redir_chain, _next) { len += sizeof(struct cfg_redir); LIST_FOREACH(s, &r->spool_chain, _next) len += sizeof(struct cfg_spool); } } IPFW_RUNLOCK(chain); data = malloc(len, M_TEMP, M_WAITOK | M_ZERO); bcopy(&nat_cnt, data, sizeof(nat_cnt)); nat_cnt = 0; len = sizeof(nat_cnt); IPFW_RLOCK(chain); if (gencnt != chain->gencnt) { free(data, M_TEMP); goto retry; } /* Serialize all the data. */ LIST_FOREACH(n, &chain->nat, _next) { bcopy(n, &data[len], sizeof(struct cfg_nat)); len += sizeof(struct cfg_nat); LIST_FOREACH(r, &n->redir_chain, _next) { bcopy(r, &data[len], sizeof(struct cfg_redir)); len += sizeof(struct cfg_redir); LIST_FOREACH(s, &r->spool_chain, _next) { bcopy(s, &data[len], sizeof(struct cfg_spool)); len += sizeof(struct cfg_spool); } } } IPFW_RUNLOCK(chain); error = sooptcopyout(sopt, data, len); free(data, M_TEMP); return (error); } static int ipfw_nat_get_log(struct sockopt *sopt) { uint8_t *data; struct cfg_nat *ptr; int i, size; struct ip_fw_chain *chain; chain = &V_layer3_chain; IPFW_RLOCK(chain); /* one pass to count, one to copy the data */ i = 0; LIST_FOREACH(ptr, &chain->nat, _next) { if (ptr->lib->logDesc == NULL) continue; i++; } size = i * (LIBALIAS_BUF_SIZE + sizeof(int)); data = malloc(size, M_IPFW, M_NOWAIT | M_ZERO); if (data == NULL) { IPFW_RUNLOCK(chain); return (ENOSPC); } i = 0; LIST_FOREACH(ptr, &chain->nat, _next) { if (ptr->lib->logDesc == NULL) continue; bcopy(&ptr->id, &data[i], sizeof(int)); i += sizeof(int); bcopy(ptr->lib->logDesc, &data[i], LIBALIAS_BUF_SIZE); i += LIBALIAS_BUF_SIZE; } IPFW_RUNLOCK(chain); sooptcopyout(sopt, data, size); free(data, M_IPFW); return(0); } static void ipfw_nat_init(void) { IPFW_WLOCK(&V_layer3_chain); /* init ipfw hooks */ ipfw_nat_ptr = ipfw_nat; lookup_nat_ptr = lookup_nat; ipfw_nat_cfg_ptr = ipfw_nat_cfg; ipfw_nat_del_ptr = ipfw_nat_del; ipfw_nat_get_cfg_ptr = ipfw_nat_get_cfg; ipfw_nat_get_log_ptr = ipfw_nat_get_log; IPFW_WUNLOCK(&V_layer3_chain); V_ifaddr_event_tag = EVENTHANDLER_REGISTER( ifaddr_event, ifaddr_change, NULL, EVENTHANDLER_PRI_ANY); } static void ipfw_nat_destroy(void) { struct cfg_nat *ptr, *ptr_temp; struct ip_fw_chain *chain; chain = &V_layer3_chain; IPFW_WLOCK(chain); LIST_FOREACH_SAFE(ptr, &chain->nat, _next, ptr_temp) { LIST_REMOVE(ptr, _next); del_redir_spool_cfg(ptr, &ptr->redir_chain); LibAliasUninit(ptr->lib); free(ptr, M_IPFW); } EVENTHANDLER_DEREGISTER(ifaddr_event, V_ifaddr_event_tag); flush_nat_ptrs(chain, -1 /* flush all */); /* deregister ipfw_nat */ ipfw_nat_ptr = NULL; lookup_nat_ptr = NULL; ipfw_nat_cfg_ptr = NULL; ipfw_nat_del_ptr = NULL; ipfw_nat_get_cfg_ptr = NULL; ipfw_nat_get_log_ptr = NULL; IPFW_WUNLOCK(chain); } static int ipfw_nat_modevent(module_t mod, int type, void *unused) { int err = 0; switch (type) { case MOD_LOAD: ipfw_nat_init(); break; case MOD_UNLOAD: ipfw_nat_destroy(); break; default: return EOPNOTSUPP; break; } return err; } static moduledata_t ipfw_nat_mod = { "ipfw_nat", ipfw_nat_modevent, 0 }; DECLARE_MODULE(ipfw_nat, ipfw_nat_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY); MODULE_DEPEND(ipfw_nat, libalias, 1, 1, 1); MODULE_DEPEND(ipfw_nat, ipfw, 2, 2, 2); MODULE_VERSION(ipfw_nat, 1); /* end of file */