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bed417288e
bird/proto/ospf/packet.c
Ondrej Zajicek bed417288e Minor fixes to previous patches.
2010-04-02 11:31:20 +02:00

530 lines
13 KiB
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/*
* BIRD -- OSPF
*
* (c) 1999--2005 Ondrej Filip <feela@network.cz>
*
* 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 proto_ospf *po = ifa->oa->po;
struct ospf_packet *pkt;
pkt = (struct ospf_packet *) buf;
pkt->version = OSPF_VERSION;
pkt->type = h_type;
pkt->routerid = htonl(po->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;
}
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;
}
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.
* @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)
{
char *mesg = "OSPF: Bad packet from ";
/* 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 proto_ospf *po = ifa->oa->po;
// struct proto *p = &po->proto;
int src_local = ifa_match_addr(ifa->addr, sk->faddr);
int dst_local = ipa_equal(sk->laddr, ifa->addr->ip);
int dst_mcast = ipa_equal(sk->laddr, AllSPFRouters) || ipa_equal(sk->laddr, AllDRouters);
#ifdef OSPFv2
/* 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;
#else /* OSPFv3 */
/* 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(L_WARN "OSPF: Received multicast packet from %I (not link-local)", sk->faddr);
#endif
/* Second, we check packet size, checksum, and the protocol version */
struct ospf_packet *ps = (struct ospf_packet *) ip_skip_header(sk->rbuf, &size);
if (ps == NULL)
{
log(L_ERR "%s%I - bad IP header", mesg, sk->faddr);
return 1;
}
if ((unsigned) size < sizeof(struct ospf_packet))
{
log(L_ERR "%s%I - too short (%u bytes)", mesg, sk->faddr, size);
return 1;
}
int osize = ntohs(ps->length);
if ((osize > size) || ((osize % 4) != 0))
{
log(L_ERR "%s%I - size field does not match (%d/%d)", mesg, sk->faddr, osize, size);
return 1;
}
if ((unsigned) size > sk->rbsize)
{
log(L_ERR "%s%I - too large (%d vs %d)", mesg, sk->faddr, size, sk->rbsize);
return 1;
}
if (ps->version != OSPF_VERSION)
{
log(L_ERR "%s%I - version %u", mesg, sk->faddr, ps->version);
return 1;
}
#ifdef OSPFv2
if ((ps->autype != htons(OSPF_AUTH_CRYPT)) &&
(!ipsum_verify(ps, 16, (void *) ps + sizeof(struct ospf_packet),
osize - sizeof(struct ospf_packet), NULL)))
{
log(L_ERR "%s%I - bad checksum", mesg, sk->faddr);
return 1;
}
#endif
/* Third, we resolve associated iface and handle vlinks. */
u32 areaid = ntohl(ps->areaid);
u32 rid = ntohl(ps->routerid);
if ((areaid == ifa->oa->areaid)
#ifdef OSPFv3
&& (ps->instance_id == ifa->instance_id)
#endif
)
{
/* It is real iface, source should be local (in OSPFv2) */
#ifdef OSPFv2
if (!src_local)
return 1;
#endif
}
else if (dst_mcast || (areaid != 0))
{
/* Obvious mismatch */
#ifdef OSPFv2
/* We ignore mismatch in OSPFv3, because there might be
other instance with different instance ID */
log(L_ERR "%s%I - area does not match (%R vs %R)",
mesg, sk->faddr, areaid, ifa->oa->areaid);
#endif
return 1;
}
else
{
/* Some vlink? */
struct ospf_iface *iff = NULL;
WALK_LIST(iff, po->iface_list)
{
if ((iff->type == OSPF_IT_VLINK) &&
(iff->voa == ifa->oa) &&
#ifdef OSPFv3
(iff->instance_id == ps->instance_id) &&
#endif
(iff->vid == rid))
{
/* Vlink should be UP */
if (iff->state != OSPF_IS_PTP)
return 1;
ifa = iff;
goto found;
}
}
#ifdef OSPFv2
log(L_WARN "OSPF: Received packet for uknown vlink (ID %R, IP %I)", rid, sk->faddr);
#endif
return 1;
}
found:
if (ifa->stub) /* This shouldn't happen */
return 1;
if (ipa_equal(sk->laddr, AllDRouters) && (ifa->sk_dr == 0))
return 1;
if (rid == po->router_id)
{
log(L_ERR "%s%I - received my own router ID!", mesg, sk->faddr);
return 1;
}
if (rid == 0)
{
log(L_ERR "%s%I - router id = 0.0.0.0", mesg, sk->faddr);
return 1;
}
/* This is deviation from RFC 2328 - neighbours should be identified by
* IP address on broadcast and NBMA networks.
*/
struct ospf_neighbor *n = find_neigh(ifa, rid);
if(!n && (ps->type != HELLO_P))
{
log(L_WARN "OSPF: Received non-hello packet from uknown neighbor (src %I, iface %s)",
sk->faddr, ifa->iface->name);
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;i<ntohs(ps->length);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 "OSPF: TX_Hook called");
}
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 "OSPF: Socket error: %m", err);
}
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_equal(ifa->drip, IPA_NONE))
ospf_send_to(ifa, ifa->drip);
if (!ipa_equal(ifa->bdrip, IPA_NONE))
ospf_send_to(ifa, ifa->bdrip);
}
void
ospf_send_to(struct ospf_iface *ifa, ip_addr dst)
{
sock *sk = ifa->sk;
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 overwritten in TX buffer");
sk_send_to(sk, len, dst, 0);
}
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