/* * BIRD -- OSPF * * (c) 1999--2005 Ondrej Filip * * Can be freely distributed and used under the terms of the GNU GPL. */ #include "ospf.h" #include "nest/password.h" #include "lib/md5.h" void ospf_pkt_fill_hdr(struct ospf_iface *ifa, void *buf, u8 h_type) { struct ospf_packet *pkt; struct proto *p = (struct proto *) (ifa->oa->po); pkt = (struct ospf_packet *) buf; pkt->version = OSPF_VERSION; pkt->type = h_type; pkt->routerid = htonl(p->cf->global->router_id); pkt->areaid = htonl(ifa->oa->areaid); #ifdef OSPFv3 pkt->instance_id = ifa->instance_id; #endif #ifdef OSPFv2 pkt->autype = htons(ifa->autype); #endif pkt->checksum = 0; } unsigned ospf_pkt_maxsize(struct ospf_iface *ifa) { /* For virtual links use mtu=576, can be mtu < 576? */ unsigned mtu = (ifa->type == OSPF_IT_VLINK) ? OSPF_VLINK_MTU : ifa->iface->mtu; unsigned add = 0; #ifdef OSPFv2 add = ((ifa->autype == OSPF_AUTH_CRYPT) ? OSPF_AUTH_CRYPT_SIZE : 0); #endif return ((mtu <= ifa->iface->mtu) ? mtu : ifa->iface->mtu) - SIZE_OF_IP_HEADER - add; } #ifdef OSPFv2 static void ospf_pkt_finalize(struct ospf_iface *ifa, struct ospf_packet *pkt) { struct password_item *passwd = NULL; void *tail; struct MD5Context ctxt; char password[OSPF_AUTH_CRYPT_SIZE]; pkt->autype = htons(ifa->autype); switch(ifa->autype) { case OSPF_AUTH_SIMPLE: bzero(&pkt->u, sizeof(union ospf_auth)); passwd = password_find(ifa->passwords, 1); if (!passwd) { log( L_ERR "No suitable password found for authentication" ); return; } password_cpy(pkt->u.password, passwd->password, sizeof(union ospf_auth)); case OSPF_AUTH_NONE: pkt->checksum = ipsum_calculate(pkt, sizeof(struct ospf_packet) - sizeof(union ospf_auth), (pkt + 1), ntohs(pkt->length) - sizeof(struct ospf_packet), NULL); break; case OSPF_AUTH_CRYPT: passwd = password_find(ifa->passwords, 0); if (!passwd) { log( L_ERR "No suitable password found for authentication" ); return; } pkt->checksum = 0; /* 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; pkt->u.md5.keyid = passwd->id; pkt->u.md5.len = OSPF_AUTH_CRYPT_SIZE; pkt->u.md5.zero = 0; pkt->u.md5.csn = htonl(ifa->csn); tail = ((void *)pkt) + ntohs(pkt->length); MD5Init(&ctxt); MD5Update(&ctxt, (char *) pkt, ntohs(pkt->length)); password_cpy(password, passwd->password, OSPF_AUTH_CRYPT_SIZE); MD5Update(&ctxt, password, OSPF_AUTH_CRYPT_SIZE); MD5Final(tail, &ctxt); break; default: bug("Unknown authentication type"); } } static int ospf_pkt_checkauth(struct ospf_neighbor *n, struct ospf_iface *ifa, struct ospf_packet *pkt, int size) { struct proto_ospf *po = ifa->oa->po; struct proto *p = &po->proto; struct password_item *pass = NULL, *ptmp; void *tail; char md5sum[OSPF_AUTH_CRYPT_SIZE]; char password[OSPF_AUTH_CRYPT_SIZE]; struct MD5Context ctxt; if (pkt->autype != htons(ifa->autype)) { OSPF_TRACE(D_PACKETS, "OSPF_auth: Method differs (%d)", ntohs(pkt->autype)); return 0; } if (n && (ifa != n->ifa)) { OSPF_TRACE(D_PACKETS, "OSPF_auth: received packet from strange interface (%s/%s)", ifa->iface->name, n->ifa->iface->name); return 0; } switch(ifa->autype) { case OSPF_AUTH_NONE: return 1; break; case OSPF_AUTH_SIMPLE: pass = password_find(ifa->passwords, 1); if (!pass) { OSPF_TRACE(D_PACKETS, "OSPF_auth: no password found"); return 0; } password_cpy(password, pass->password, sizeof(union ospf_auth)); if (memcmp(pkt->u.password, password, sizeof(union ospf_auth))) { char ppass[sizeof(union ospf_auth) + 1]; bzero(ppass, (sizeof(union ospf_auth) + 1)); memcpy(ppass, pkt->u.password, sizeof(union ospf_auth)); OSPF_TRACE(D_PACKETS, "OSPF_auth: different passwords (%s)", ppass); return 0; } return 1; break; case OSPF_AUTH_CRYPT: if (pkt->u.md5.len != OSPF_AUTH_CRYPT_SIZE) { OSPF_TRACE(D_PACKETS, "OSPF_auth: wrong size of md5 digest"); return 0; } if (ntohs(pkt->length) + OSPF_AUTH_CRYPT_SIZE != size) { OSPF_TRACE(D_PACKETS, "OSPF_auth: size mismatch (%d vs %d)", ntohs(pkt->length) + OSPF_AUTH_CRYPT_SIZE, size); return 0; } if (pkt->u.md5.zero) { OSPF_TRACE(D_PACKETS, "OSPF_auth: \"zero\" area is non-zero"); return 0; } tail = ((void *)pkt) + ntohs(pkt->length); if (ifa->passwords) { WALK_LIST(ptmp, *(ifa->passwords)) { if (pkt->u.md5.keyid != ptmp->id) continue; if ((ptmp->accfrom > now_real) || (ptmp->accto < now_real)) continue; pass = ptmp; break; } } if (!pass) { OSPF_TRACE(D_PACKETS, "OSPF_auth: no suitable md5 password found"); return 0; } if (n) { u32 rcv_csn = ntohl(pkt->u.md5.csn); if(rcv_csn < n->csn) { OSPF_TRACE(D_PACKETS, "OSPF_auth: lower sequence number (rcv %d, old %d)", rcv_csn, n->csn); return 0; } n->csn = rcv_csn; } MD5Init(&ctxt); MD5Update(&ctxt, (char *) pkt, ntohs(pkt->length)); password_cpy(password, pass->password, OSPF_AUTH_CRYPT_SIZE); MD5Update(&ctxt, password, OSPF_AUTH_CRYPT_SIZE); MD5Final(md5sum, &ctxt); if (memcmp(md5sum, tail, OSPF_AUTH_CRYPT_SIZE)) { OSPF_TRACE(D_PACKETS, "OSPF_auth: wrong md5 digest"); return 0; } return 1; break; default: OSPF_TRACE(D_PACKETS, "OSPF_auth: unknown auth type"); return 0; } } #else /* OSPFv3 authentication not yet supported */ static inline void ospf_pkt_finalize(struct ospf_iface *ifa, struct ospf_packet *pkt) { } static int ospf_pkt_checkauth(struct ospf_neighbor *n, struct ospf_iface *ifa, struct ospf_packet *pkt, int size) { return 1; } #endif /** * ospf_rx_hook * @sk: socket we received the packet. Its ignored. * @size: size 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, int size) { struct ospf_packet *ps; struct ospf_iface *ifa = (struct ospf_iface *) (sk->data); struct proto_ospf *po = ifa->oa->po; struct proto *p = &po->proto; struct ospf_neighbor *n; int osize; char *mesg = "Bad OSPF packet from "; struct ospf_iface *iff; if (ifa->stub) return (1); ps = (struct ospf_packet *) ipv4_skip_header(sk->rbuf, &size); if (ps == NULL) { log(L_ERR "%s%I - bad IP header", mesg, sk->faddr); return 1; } if ((ifa->oa->areaid != 0) && (ntohl(ps->areaid) == 0)) { WALK_LIST(iff, po->iface_list) { if ((iff->type == OSPF_IT_VLINK) && (iff->iface == ifa->iface) && (iff->voa = ifa->oa) && ipa_equal(sk->faddr, iff->vip)) { return 1; /* Packet is for VLINK */ } } } DBG("%s: RX_Hook called on interface %s.\n", p->name, sk->iface->name); osize = ntohs(ps->length); if ((unsigned) size < sizeof(struct ospf_packet)) { log(L_ERR "%s%I - too short (%u bytes)", mesg, sk->faddr, size); return 1; } if ((osize > size) || (osize != (4 * (osize / 4)))) { log(L_ERR "%s%I - size field does not match (%d/%d)", mesg, sk->faddr, ntohs(ps->length), size ); return 1; } if (ps->version != OSPF_VERSION) { log(L_ERR "%s%I - version %u", mesg, sk->faddr, ps->version); return 1; } /* FIXME - handle checksums in OSPFv3 */ #ifdef OSPFv2 if ((ps->autype != htons(OSPF_AUTH_CRYPT)) && (!ipsum_verify(ps, 16, (void *) ps + sizeof(struct ospf_packet), ntohs(ps->length) - sizeof(struct ospf_packet), NULL))) { log(L_ERR "%s%I - bad checksum", mesg, sk->faddr); return 1; } #endif if (ntohl(ps->areaid) != ifa->oa->areaid) { log(L_ERR "%s%I - different area (%u)", mesg, sk->faddr, ntohl(ps->areaid)); return 1; } /* FIXME - handling of instance id should be better */ #ifdef OSPFv3 if (ps->instance_id != ifa->instance_id) { log(L_ERR "%s%I - different instance (%u)", mesg, sk->faddr, ps->instance_id); return 1; } #endif if (ntohl(ps->routerid) == p->cf->global->router_id) { log(L_ERR "%s%I - received my own router ID!", mesg, sk->faddr); return 1; } if (ntohl(ps->routerid) == 0) { log(L_ERR "%s%I - router id = 0.0.0.0", mesg, sk->faddr); return 1; } if (((unsigned) size > sk->rbsize) || (ntohs(ps->length) > sk->rbsize)) { log(L_ERR "%s%I - packet is too large (%d-%d vs %d)", mesg, sk->faddr, size, ntohs(ps->length), sk->rbsize); return 1; } /* This is deviation from RFC 2328 - neighbours should be identified by * IP address on broadcast and NBMA networks. */ n = find_neigh(ifa, ntohl(((struct ospf_packet *) ps)->routerid)); if(!n && (ps->type != HELLO_P)) { OSPF_TRACE(D_PACKETS, "Received non-hello packet from uknown neighbor (%I)", sk->faddr); return 1; } if (!ospf_pkt_checkauth(n, ifa, ps, size)) { log(L_ERR "%s%I - authentification failed", mesg, sk->faddr); return 1; } /* Dump packet pu8=(u8 *)(sk->rbuf+5*4); for(i=0;ilength);i+=4) DBG("%s: received %u,%u,%u,%u\n",p->name, pu8[i+0], pu8[i+1], pu8[i+2], pu8[i+3]); DBG("%s: received size: %u\n",p->name,size); */ switch (ps->type) { case HELLO_P: DBG("%s: Hello received.\n", p->name); ospf_hello_receive(ps, ifa, n, sk->faddr); break; case DBDES_P: DBG("%s: Database description received.\n", p->name); ospf_dbdes_receive(ps, ifa, n); break; case LSREQ_P: DBG("%s: Link state request received.\n", p->name); ospf_lsreq_receive(ps, ifa, n); break; case LSUPD_P: DBG("%s: Link state update received.\n", p->name); ospf_lsupd_receive(ps, ifa, n); break; case LSACK_P: DBG("%s: Link state ack received.\n", p->name); ospf_lsack_receive(ps, ifa, n); break; default: log(L_ERR "%s%I - wrong type %u", mesg, sk->faddr, ps->type); return 1; }; return 1; } void ospf_tx_hook(sock * sk) { struct ospf_iface *ifa= (struct ospf_iface *) (sk->data); struct proto *p = (struct proto *) (ifa->oa->po); log(L_ERR "%s: TX_Hook called on interface %s\n", p->name, sk->iface->name); } void ospf_err_hook(sock * sk, int err) { struct ospf_iface *ifa= (struct ospf_iface *) (sk->data); struct proto *p = (struct proto *) (ifa->oa->po); log(L_ERR "%s: Err_Hook called on interface %s with err=%d\n", p->name, sk->iface->name, err); } void ospf_send_to_agt(sock * sk, struct ospf_iface *ifa, u8 state) { struct ospf_neighbor *n; WALK_LIST(n, ifa->neigh_list) if (n->state >= state) ospf_send_to(sk, n->ip, ifa); } void ospf_send_to_bdr(sock * sk, struct ospf_iface *ifa) { if (!ipa_equal(ifa->drip, IPA_NONE)) ospf_send_to(sk, ifa->drip, ifa); if (!ipa_equal(ifa->bdrip, IPA_NONE)) ospf_send_to(sk, ifa->bdrip, ifa); } void ospf_send_to(sock *sk, ip_addr ip, struct ospf_iface *ifa) { struct ospf_packet *pkt = (struct ospf_packet *) sk->tbuf; int len = ntohs(pkt->length); #ifdef OSPFv2 if (ifa->autype == OSPF_AUTH_CRYPT) len += OSPF_AUTH_CRYPT_SIZE; #endif ospf_pkt_finalize(ifa, pkt); if (sk->tbuf != sk->tpos) log(L_ERR "Aiee, old packet was overwritted in TX buffer"); if (ipa_equal(ip, IPA_NONE)) sk_send(sk, len); else sk_send_to(sk, len, ip, OSPF_PROTO); }