/* * BIRD -- OSPF * * (c) 1999--2005 Ondrej Filip <feela@network.cz> * (c) 2009--2014 Ondrej Zajicek <santiago@crfreenet.org> * (c) 2009--2014 CZ.NIC z.s.p.o. * * Can be freely distributed and used under the terms of the GNU GPL. */ #include "ospf.h" #include "nest/password.h" #include "lib/md5.h" #include "lib/mac.h" #include "lib/socket.h" void ospf_pkt_fill_hdr(struct ospf_iface *ifa, void *buf, u8 h_type) { struct ospf_proto *p = ifa->oa->po; struct ospf_packet *pkt; pkt = (struct ospf_packet *) buf; pkt->version = ospf_get_version(p); pkt->type = h_type; pkt->length = htons(ospf_pkt_maxsize(ifa)); pkt->routerid = htonl(p->router_id); pkt->areaid = htonl(ifa->oa->areaid); pkt->checksum = 0; pkt->instance_id = ifa->instance_id; pkt->autype = ifa->autype; } /* We assume OSPFv2 in ospf_pkt_finalize() */ static void ospf_pkt_finalize(struct ospf_iface *ifa, struct ospf_packet *pkt, uint *plen) { struct password_item *pass = NULL; union ospf_auth *auth = (void *) (pkt + 1); pkt->checksum = 0; pkt->autype = ifa->autype; bzero(auth, sizeof(union ospf_auth)); /* Compatibility note: auth may contain anything if autype is none, but nonzero values do not work with Mikrotik OSPF */ switch (ifa->autype) { case OSPF_AUTH_SIMPLE: pass = password_find(ifa->passwords, 1); if (!pass) { log(L_ERR "No suitable password found for authentication"); return; } strncpy(auth->password, pass->password, sizeof(auth->password)); case OSPF_AUTH_NONE: { void *body = (void *) (auth + 1); uint blen = *plen - sizeof(struct ospf_packet) - sizeof(union ospf_auth); pkt->checksum = ipsum_calculate(pkt, sizeof(struct ospf_packet), body, blen, NULL); } break; case OSPF_AUTH_CRYPT: pass = password_find(ifa->passwords, 0); if (!pass) { log(L_ERR "No suitable password found for authentication"); return; } /* Perhaps use random value to prevent replay attacks after reboot when system does not have independent RTC? */ if (!ifa->csn) { ifa->csn = (u32) now; ifa->csn_use = now; } /* We must have sufficient delay between sending a packet and increasing CSN to prevent reordering of packets (in a network) with different CSNs */ if ((now - ifa->csn_use) > 1) ifa->csn++; ifa->csn_use = now; uint auth_len = mac_type_length(pass->alg); byte *auth_tail = ((byte *) pkt + *plen); *plen += auth_len; ASSERT(*plen < ifa->sk->tbsize); auth->c32.zero = 0; auth->c32.keyid = pass->id; auth->c32.len = auth_len; auth->c32.csn = htonl(ifa->csn); /* Append key for keyed hash, append padding for HMAC (RFC 5709 3.3) */ if (pass->alg < ALG_HMAC) strncpy(auth_tail, pass->password, auth_len); else memset32(auth_tail, HMAC_MAGIC, auth_len / 4); mac_fill(pass->alg, pass->password, pass->length, (byte *) pkt, *plen, auth_tail); break; default: bug("Unknown authentication type"); } } /* We assume OSPFv2 in ospf_pkt_checkauth() */ static int ospf_pkt_checkauth(struct ospf_neighbor *n, struct ospf_iface *ifa, struct ospf_packet *pkt, uint len) { struct ospf_proto *p = ifa->oa->po; union ospf_auth *auth = (void *) (pkt + 1); struct password_item *pass = NULL; const char *err_dsc = NULL; uint err_val = 0; uint plen = ntohs(pkt->length); u8 autype = pkt->autype; if (autype != ifa->autype) DROP("authentication method mismatch", autype); switch (autype) { case OSPF_AUTH_NONE: return 1; case OSPF_AUTH_SIMPLE: pass = password_find(ifa->passwords, 1); if (!pass) DROP1("no password found"); if (!password_verify(pass, auth->password, sizeof(auth->password))) DROP("wrong password", pass->id); return 1; case OSPF_AUTH_CRYPT: pass = password_find_by_id(ifa->passwords, auth->c32.keyid); if (!pass) DROP("no suitable password found", auth->c32.keyid); uint auth_len = mac_type_length(pass->alg); if (plen + auth->c32.len > len) DROP("packet length mismatch", len); if (auth->c32.len != auth_len) DROP("wrong authentication length", auth->c32.len); u32 rcv_csn = ntohl(auth->c32.csn); if (n && (rcv_csn < n->csn)) // DROP("lower sequence number", rcv_csn); { /* We want to report both new and old CSN */ LOG_PKT_AUTH("Authentication failed for nbr %R on %s - " "lower sequence number (rcv %u, old %u)", n->rid, ifa->ifname, rcv_csn, n->csn); return 0; } byte *auth_tail = ((byte *) pkt) + plen; byte *auth_data = alloca(auth_len); memcpy(auth_data, auth_tail, auth_len); /* Append key for keyed hash, append padding for HMAC (RFC 5709 3.3) */ if (pass->alg < ALG_HMAC) strncpy(auth_tail, pass->password, auth_len); else memset32(auth_tail, HMAC_MAGIC, auth_len / 4); if (!mac_verify(pass->alg, pass->password, pass->length, (byte *) pkt, plen + auth_len, auth_data)) DROP("wrong authentication code", pass->id); if (n) n->csn = rcv_csn; return 1; default: bug("Unknown authentication type"); } drop: LOG_PKT_AUTH("Authentication failed for nbr %R on %s - %s (%u)", (n ? n->rid : ntohl(pkt->routerid)), ifa->ifname, err_dsc, err_val); return 0; } /** * ospf_rx_hook * @sk: socket we received the packet. * @len: length of the packet * * This is the entry point for messages from neighbors. Many checks (like * authentication, checksums, size) are done before the packet is passed to * non generic functions. */ int ospf_rx_hook(sock *sk, uint len) { /* We want just packets from sk->iface. Unfortunately, on BSD we cannot filter out other packets at kernel level and we receive all packets on all sockets */ if (sk->lifindex != sk->iface->index) return 1; DBG("OSPF: RX hook called (iface %s, src %I, dst %I)\n", sk->iface->name, sk->faddr, sk->laddr); /* Initially, the packet is associated with the 'master' iface */ struct ospf_iface *ifa = sk->data; struct ospf_proto *p = ifa->oa->po; const char *err_dsc = NULL; uint err_val = 0; /* Should not happen */ if (ifa->state <= OSPF_IS_LOOP) return 1; int src_local, dst_local, dst_mcast; src_local = ipa_in_netX(sk->faddr, &ifa->addr->prefix); dst_local = ipa_equal(sk->laddr, ifa->addr->ip); dst_mcast = ipa_equal(sk->laddr, ifa->all_routers) || ipa_equal(sk->laddr, ifa->des_routers); if (ospf_is_v2(p)) { /* First, we eliminate packets with strange address combinations. * In OSPFv2, they might be for other ospf_ifaces (with different IP * prefix) on the same real iface, so we don't log it. We enforce * that (src_local || dst_local), therefore we are eliminating all * such cases. */ if (dst_mcast && !src_local) return 1; if (!dst_mcast && !dst_local) return 1; /* Ignore my own broadcast packets */ if (ifa->cf->real_bcast && ipa_equal(sk->faddr, ifa->addr->ip)) return 1; } else { /* In OSPFv3, src_local and dst_local mean link-local. * RFC 5340 says that local (non-vlink) packets use * link-local src address, but does not enforce it. Strange. */ if (dst_mcast && !src_local) LOG_PKT_WARN("Multicast packet received from non-link-local %I via %s", sk->faddr, ifa->ifname); } /* Second, we check packet length, checksum, and the protocol version */ struct ospf_packet *pkt = (void *) sk_rx_buffer(sk, &len); if (pkt == NULL) DROP("bad IP header", len); if (len < sizeof(struct ospf_packet)) DROP("too short", len); if (pkt->version != ospf_get_version(p)) DROP("version mismatch", pkt->version); uint plen = ntohs(pkt->length); if ((plen < sizeof(struct ospf_packet)) || ((plen % 4) != 0)) DROP("invalid length", plen); if (sk->flags & SKF_TRUNCATED) { /* If we have dynamic buffers and received truncated message, we expand RX buffer */ uint bs = plen + 256; bs = BIRD_ALIGN(bs, 1024); if (!ifa->cf->rx_buffer && (bs > sk->rbsize)) sk_set_rbsize(sk, bs); DROP("truncated", plen); } if (plen > len) DROP("length mismatch", plen); if (ospf_is_v2(p) && (pkt->autype != OSPF_AUTH_CRYPT)) { uint hlen = sizeof(struct ospf_packet) + sizeof(union ospf_auth); uint blen = plen - hlen; void *body = ((void *) pkt) + hlen; if (!ipsum_verify(pkt, sizeof(struct ospf_packet), body, blen, NULL)) DROP1("invalid checksum"); } /* Third, we resolve associated iface and handle vlinks. */ u32 areaid = ntohl(pkt->areaid); u32 rid = ntohl(pkt->routerid); u8 instance_id = pkt->instance_id; if (areaid == ifa->oa->areaid) { /* Matching area ID */ if (instance_id != ifa->instance_id) return 1; /* It is real iface, source should be local (in OSPFv2) */ if (ospf_is_v2(p) && !src_local) DROP1("strange source address"); goto found; } else if ((areaid == 0) && !dst_mcast) { /* Backbone area ID and possible vlink packet */ if ((p->areano == 1) || !oa_is_ext(ifa->oa)) return 1; struct ospf_iface *iff = NULL; WALK_LIST(iff, p->iface_list) { if ((iff->type == OSPF_IT_VLINK) && (iff->voa == ifa->oa) && (iff->instance_id == instance_id) && (iff->vid == rid)) { /* Vlink should be UP */ if (iff->state != OSPF_IS_PTP) return 1; ifa = iff; goto found; } } /* * Cannot find matching vlink. It is either misconfigured vlink; NBMA or * PtMP with misconfigured area ID, or packet for some other instance (that * is possible even if instance_id == ifa->instance_id, because it may be * also vlink packet in the other instance, which is different namespace). */ return 1; } else { /* Non-matching area ID but cannot be vlink packet */ if (instance_id != ifa->instance_id) return 1; DROP("area mismatch", areaid); } found: if (ifa->stub) /* This shouldn't happen */ return 1; if (ipa_equal(sk->laddr, ifa->des_routers) && (ifa->sk_dr == 0)) return 1; /* TTL check must be done after instance dispatch */ if (ifa->check_ttl && (sk->rcv_ttl < 255)) DROP("wrong TTL", sk->rcv_ttl); if (rid == p->router_id) DROP1("my own router ID"); if (rid == 0) DROP1("zero router ID"); /* In OSPFv2, neighbors are identified by either IP or Router ID, based on network type */ uint t = ifa->type; struct ospf_neighbor *n; if (ospf_is_v2(p) && ((t == OSPF_IT_BCAST) || (t == OSPF_IT_NBMA) || (t == OSPF_IT_PTMP))) n = find_neigh_by_ip(ifa, sk->faddr); else n = find_neigh(ifa, rid); if (!n && (pkt->type != HELLO_P)) { OSPF_TRACE(D_PACKETS, "Non-HELLO packet received from unknown nbr %R on %s, src %I", rid, ifa->ifname, sk->faddr); return 1; } /* ospf_pkt_checkauth() has its own error logging */ if (ospf_is_v2(p) && !ospf_pkt_checkauth(n, ifa, pkt, len)) return 1; switch (pkt->type) { case HELLO_P: ospf_receive_hello(pkt, ifa, n, sk->faddr); break; case DBDES_P: ospf_receive_dbdes(pkt, ifa, n); break; case LSREQ_P: ospf_receive_lsreq(pkt, ifa, n); break; case LSUPD_P: ospf_receive_lsupd(pkt, ifa, n); break; case LSACK_P: ospf_receive_lsack(pkt, ifa, n); break; default: DROP("invalid packet type", pkt->type); }; return 1; drop: LOG_PKT("Bad packet from %I via %s - %s (%u)", sk->faddr, ifa->ifname, err_dsc, err_val); return 1; } /* void ospf_tx_hook(sock * sk) { struct ospf_iface *ifa= (struct ospf_iface *) (sk->data); // struct proto *p = (struct proto *) (ifa->oa->p); log(L_ERR "OSPF: TX hook called on %s", ifa->ifname); } */ void ospf_err_hook(sock * sk, int err) { struct ospf_iface *ifa= (struct ospf_iface *) (sk->data); struct ospf_proto *p = ifa->oa->po; log(L_ERR "%s: Socket error on %s: %M", p->p.name, ifa->ifname, err); } void ospf_verr_hook(sock *sk, int err) { struct ospf_proto *p = (struct ospf_proto *) (sk->data); log(L_ERR "%s: Vlink socket error: %M", p->p.name, err); } void ospf_send_to(struct ospf_iface *ifa, ip_addr dst) { sock *sk = ifa->sk; struct ospf_packet *pkt = (struct ospf_packet *) sk->tbuf; uint plen = ntohs(pkt->length); if (ospf_is_v2(ifa->oa->po)) ospf_pkt_finalize(ifa, pkt, &plen); int done = sk_send_to(sk, plen, dst, 0); if (!done) log(L_WARN "OSPF: TX queue full on %s", ifa->ifname); } void ospf_send_to_agt(struct ospf_iface *ifa, u8 state) { struct ospf_neighbor *n; WALK_LIST(n, ifa->neigh_list) if (n->state >= state) ospf_send_to(ifa, n->ip); } void ospf_send_to_bdr(struct ospf_iface *ifa) { if (ipa_nonzero2(ifa->drip)) ospf_send_to(ifa, ifa->drip); if (ipa_nonzero2(ifa->bdrip)) ospf_send_to(ifa, ifa->bdrip); }