/*- * 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 #include #include #include #include #include #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 #include #include /* XXX for in_cksum */ MALLOC_DECLARE(M_IPFW); extern struct ip_fw_chain layer3_chain; static eventhandler_tag ifaddr_event_tag; extern ipfw_nat_t *ipfw_nat_ptr; extern ipfw_nat_cfg_t *ipfw_nat_cfg_ptr; extern ipfw_nat_cfg_t *ipfw_nat_del_ptr; extern ipfw_nat_cfg_t *ipfw_nat_get_cfg_ptr; extern ipfw_nat_cfg_t *ipfw_nat_get_log_ptr; static void ifaddr_change(void *arg __unused, struct ifnet *ifp) { struct cfg_nat *ptr; struct ifaddr *ifa; IPFW_WLOCK(&V_layer3_chain); /* Check every nat entry... */ LIST_FOREACH(ptr, &V_layer3_chain.nat, _next) { /* ...using nic 'ifp->if_xname' as dynamic alias address. */ if (strncmp(ptr->if_name, ifp->if_xname, IF_NAMESIZE) == 0) { mtx_lock(&ifp->if_addr_mtx); TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list) { 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); } mtx_unlock(&ifp->if_addr_mtx); } } IPFW_WUNLOCK(&V_layer3_chain); } static void flush_nat_ptrs(const int i) { struct ip_fw *rule; IPFW_WLOCK_ASSERT(&V_layer3_chain); for (rule = V_layer3_chain.rules; rule; rule = rule->next) { ipfw_insn_nat *cmd = (ipfw_insn_nat *)ACTION_PTR(rule); if (cmd->o.opcode != O_NAT) continue; if (cmd->nat != NULL && cmd->nat->id == i) cmd->nat = NULL; } } #define HOOK_NAT(b, p) do { \ IPFW_WLOCK_ASSERT(&V_layer3_chain); \ LIST_INSERT_HEAD(b, p, _next); \ } while (0) #define UNHOOK_NAT(p) do { \ IPFW_WLOCK_ASSERT(&V_layer3_chain); \ LIST_REMOVE(p, _next); \ } while (0) #define HOOK_REDIR(b, p) do { \ LIST_INSERT_HEAD(b, p, _next); \ } while (0) #define HOOK_SPOOL(b, p) do { \ LIST_INSERT_HEAD(b, p, _next); \ } while (0) 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 int 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; char *panic_err; 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; } if (r->alink[0] == NULL) { panic_err = "LibAliasRedirect* returned NULL"; goto bad; } else /* 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. */ HOOK_SPOOL(&r->spool_chain, s); } /* And finally hook this redir entry. */ HOOK_REDIR(&ptr->redir_chain, r); } return (1); bad: /* something really bad happened: panic! */ panic("%s\n", panic_err); } 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; char *c; ldt = 0; retval = 0; if ((mcl = m_megapullup(m, m->m_pkthdr.len)) == NULL) goto badnat; ip = mtod(mcl, struct ip *); if (args->eh == NULL) { ip->ip_len = htons(ip->ip_len); ip->ip_off = htons(ip->ip_off); } /* * XXX - Libalias checksum offload 'duct tape': * * locally generated packets have only * pseudo-header checksum calculated * and libalias will screw it[1], so * mark them for later fix. Moreover * there are cases when libalias * modify tcp packet data[2], mark it * for later fix too. * * [1] libalias was never meant to run * in kernel, so it doesn't have any * knowledge about checksum * offloading, and it 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 screw it. * * [2] when libalias modify tcp's data * content, full TCP checksum has to * be recomputed: the problem is that * libalias doesn't have any idea * about checksum offloading To * workaround 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 *); 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)); if (retval != PKT_ALIAS_OK && retval != PKT_ALIAS_FOUND_HEADER_FRAGMENT) { /* XXX - should i add some logging? */ m_free(mcl); badnat: args->m = NULL; return (IP_FW_DENY); } 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 * by ourself. */ 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); } if (args->eh == NULL) { ip->ip_len = ntohs(ip->ip_len); ip->ip_off = ntohs(ip->ip_off); } args->m = mcl; return (IP_FW_NAT); } static int ipfw_nat_cfg(struct sockopt *sopt) { struct cfg_nat *ptr, *ser_n; char *buf; buf = malloc(NAT_BUF_LEN, M_IPFW, M_WAITOK | M_ZERO); sooptcopyin(sopt, buf, NAT_BUF_LEN, sizeof(struct cfg_nat)); ser_n = (struct cfg_nat *)buf; /* * Find/create nat rule. */ IPFW_WLOCK(&V_layer3_chain); LOOKUP_NAT(V_layer3_chain, ser_n->id, ptr); if (ptr == NULL) { /* New rule: allocate and init new instance. */ ptr = malloc(sizeof(struct cfg_nat), M_IPFW, M_NOWAIT | M_ZERO); if (ptr == NULL) { IPFW_WUNLOCK(&V_layer3_chain); free(buf, M_IPFW); return (ENOSPC); } ptr->lib = LibAliasInit(NULL); if (ptr->lib == NULL) { IPFW_WUNLOCK(&V_layer3_chain); free(ptr, M_IPFW); free(buf, M_IPFW); return (EINVAL); } LIST_INIT(&ptr->redir_chain); } else { /* Entry already present: temporarly unhook it. */ UNHOOK_NAT(ptr); flush_nat_ptrs(ser_n->id); } IPFW_WUNLOCK(&V_layer3_chain); /* * Basic nat configuration. */ ptr->id = ser_n->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 = ser_n->ip; ptr->redir_cnt = ser_n->redir_cnt; ptr->mode = ser_n->mode; LibAliasSetMode(ptr->lib, ser_n->mode, ser_n->mode); LibAliasSetAddress(ptr->lib, ptr->ip); memcpy(ptr->if_name, ser_n->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); free(buf, M_IPFW); IPFW_WLOCK(&V_layer3_chain); HOOK_NAT(&V_layer3_chain.nat, ptr); IPFW_WUNLOCK(&V_layer3_chain); return (0); } static int ipfw_nat_del(struct sockopt *sopt) { struct cfg_nat *ptr; int i; sooptcopyin(sopt, &i, sizeof i, sizeof i); IPFW_WLOCK(&V_layer3_chain); LOOKUP_NAT(V_layer3_chain, i, ptr); if (ptr == NULL) { IPFW_WUNLOCK(&V_layer3_chain); return (EINVAL); } UNHOOK_NAT(ptr); flush_nat_ptrs(i); IPFW_WUNLOCK(&V_layer3_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) { uint8_t *data; struct cfg_nat *n; struct cfg_redir *r; struct cfg_spool *s; int nat_cnt, off; nat_cnt = 0; off = sizeof(nat_cnt); data = malloc(NAT_BUF_LEN, M_IPFW, M_WAITOK | M_ZERO); IPFW_RLOCK(&V_layer3_chain); /* Serialize all the data. */ LIST_FOREACH(n, &V_layer3_chain.nat, _next) { nat_cnt++; if (off + SOF_NAT < NAT_BUF_LEN) { bcopy(n, &data[off], SOF_NAT); off += SOF_NAT; LIST_FOREACH(r, &n->redir_chain, _next) { if (off + SOF_REDIR < NAT_BUF_LEN) { bcopy(r, &data[off], SOF_REDIR); off += SOF_REDIR; LIST_FOREACH(s, &r->spool_chain, _next) { if (off + SOF_SPOOL < NAT_BUF_LEN) { bcopy(s, &data[off], SOF_SPOOL); off += SOF_SPOOL; } else goto nospace; } } else goto nospace; } } else goto nospace; } bcopy(&nat_cnt, data, sizeof(nat_cnt)); IPFW_RUNLOCK(&V_layer3_chain); sooptcopyout(sopt, data, NAT_BUF_LEN); free(data, M_IPFW); return (0); nospace: IPFW_RUNLOCK(&V_layer3_chain); printf("serialized data buffer not big enough:" "please increase NAT_BUF_LEN\n"); free(data, M_IPFW); return (ENOSPC); } static int ipfw_nat_get_log(struct sockopt *sopt) { uint8_t *data; struct cfg_nat *ptr; int i, size, cnt, sof; data = NULL; sof = LIBALIAS_BUF_SIZE; cnt = 0; IPFW_RLOCK(&V_layer3_chain); size = i = 0; LIST_FOREACH(ptr, &V_layer3_chain.nat, _next) { if (ptr->lib->logDesc == NULL) continue; cnt++; size = cnt * (sof + sizeof(int)); data = realloc(data, size, M_IPFW, M_NOWAIT | M_ZERO); if (data == NULL) { IPFW_RUNLOCK(&V_layer3_chain); return (ENOSPC); } bcopy(&ptr->id, &data[i], sizeof(int)); i += sizeof(int); bcopy(ptr->lib->logDesc, &data[i], sof); i += sof; } IPFW_RUNLOCK(&V_layer3_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; 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 ip_fw *rule; struct cfg_nat *ptr, *ptr_temp; IPFW_WLOCK(&V_layer3_chain); LIST_FOREACH_SAFE(ptr, &V_layer3_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 all nat ptrs */ for (rule = V_layer3_chain.rules; rule; rule = rule->next) { ipfw_insn_nat *cmd = (ipfw_insn_nat *)ACTION_PTR(rule); if (cmd->o.opcode == O_NAT) cmd->nat = NULL; } /* deregister ipfw_nat */ ipfw_nat_ptr = NULL; IPFW_WUNLOCK(&V_layer3_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);