bgpd: fix ipv4-mapped ipv6 use cases

bgpd/bgp_nht.c

@@ -320,11 +320,6 @@ int bgp_find_or_add_nexthop(struct bgp *bgp_route, struct bgp *bgp_nexthop,
  afi = BGP_ATTR_MP_NEXTHOP_LEN_IP6(pi->attr) ? AFI_IP6
  : AFI_IP;
 
- /* Validation for the ipv4 mapped ipv6 nexthop. */
- if (IS_MAPPED_IPV6(&pi->attr->mp_nexthop_global)) {
- afi = AFI_IP;
- }
-
  /* This will return true if the global IPv6 NH is a link local
  * addr */
  if (make_prefix(afi, pi, &p) < 0)
@@ -355,7 +350,9 @@ int bgp_find_or_add_nexthop(struct bgp *bgp_route, struct bgp *bgp_nexthop,
  }
  return 0;
  }
-
+ if (afi == AFI_IP6 && p.family == AF_INET)
+ /* IPv4 mapped IPv6 nexthop address */
+ afi = AFI_IP;
  srte_color = bgp_attr_get_color(pi->attr);
 
  } else if (peer) {
@@ -1047,19 +1044,11 @@ static int make_prefix(int afi, struct bgp_path_info *pi, struct prefix *p)
  p->u.prefix4 = p_orig->u.prefix4;
  p->prefixlen = p_orig->prefixlen;
  } else {
- if (IS_MAPPED_IPV6(&pi->attr->mp_nexthop_global)) {
- ipv4_mapped_ipv6_to_ipv4(
- &pi->attr->mp_nexthop_global, &ipv4);
- p->u.prefix4 = ipv4;
- p->prefixlen = IPV4_MAX_BITLEN;
- } else {
- if (p_orig->family == AF_EVPN)
- p->u.prefix4 =
- pi->attr->mp_nexthop_global_in;
- else
- p->u.prefix4 = pi->attr->nexthop;
- p->prefixlen = IPV4_MAX_BITLEN;
- }
+ if (p_orig->family == AF_EVPN)
+ p->u.prefix4 = pi->attr->mp_nexthop_global_in;
+ else
+ p->u.prefix4 = pi->attr->nexthop;
+ p->prefixlen = IPV4_MAX_BITLEN;
  }
  break;
  case AFI_IP6:
@@ -1075,6 +1064,7 @@ static int make_prefix(int afi, struct bgp_path_info *pi, struct prefix *p)
  /* If we receive MP_REACH nexthop with ::(LL)
  * or LL(LL), use LL address as nexthop cache.
  */
+ p->prefixlen = IPV6_MAX_BITLEN;
  if (pi->attr &&
  pi->attr->mp_nexthop_len ==
  BGP_ATTR_NHLEN_IPV6_GLOBAL_AND_LL &&
@@ -1088,16 +1078,28 @@ static int make_prefix(int afi, struct bgp_path_info *pi, struct prefix *p)
  else if (pi->attr &&
  pi->attr->mp_nexthop_len ==
  BGP_ATTR_NHLEN_IPV6_GLOBAL_AND_LL) {
- if (CHECK_FLAG(pi->attr->nh_flags,
- BGP_ATTR_NH_MP_PREFER_GLOBAL))
- p->u.prefix6 =
- pi->attr->mp_nexthop_global;
- else
+ if (CHECK_FLAG(pi->attr->nh_flags, BGP_ATTR_NH_MP_PREFER_GLOBAL)) {
+ if (IS_MAPPED_IPV6(&pi->attr->mp_nexthop_global)) {
+ ipv4_mapped_ipv6_to_ipv4(&pi->attr->mp_nexthop_global,
+ &ipv4);
+ p->u.prefix4 = ipv4;
+ p->prefixlen = IPV4_MAX_BITLEN;
+ p->family = AF_INET;
+ } else
+ p->u.prefix6 = pi->attr->mp_nexthop_global;
+ } else
  p->u.prefix6 =
  pi->attr->mp_nexthop_local;
- } else
- p->u.prefix6 = pi->attr->mp_nexthop_global;
- p->prefixlen = IPV6_MAX_BITLEN;
+ } else {
+ if (IS_MAPPED_IPV6(&pi->attr->mp_nexthop_global)) {
+ ipv4_mapped_ipv6_to_ipv4(&pi->attr->mp_nexthop_global,
+ &ipv4);
+ p->u.prefix4 = ipv4;
+ p->prefixlen = IPV4_MAX_BITLEN;
+ p->family = AF_INET;
+ } else
+ p->u.prefix6 = pi->attr->mp_nexthop_global;
+ }
  }
  break;
  default:

bgpd/bgp_route.c

@@ -9710,11 +9710,7 @@ void route_vty_out(struct vty *vty, const struct prefix *p,
  json_object_string_add(json_nexthop_ll, "scope",
  "link-local");
 
- if ((IPV6_ADDR_CMP(&attr->mp_nexthop_global,
- &attr->mp_nexthop_local) !=
- 0) &&
- !CHECK_FLAG(attr->nh_flags,
- BGP_ATTR_NH_MP_PREFER_GLOBAL))
+ if (!CHECK_FLAG(attr->nh_flags, BGP_ATTR_NH_MP_PREFER_GLOBAL))
  json_object_boolean_true_add(
  json_nexthop_ll, "used");
  else

bgpd/bgp_updgrp_packet.c

@@ -508,6 +508,9 @@ struct stream *bpacket_reformat_for_peer(struct bpacket *pkt,
  gnh_modified = 1;
  }
  } else if (IN6_IS_ADDR_UNSPECIFIED(&v6nhglobal)) {
+ /* the UPDATE is originating from the local router.
+ * Build the global nexthop.
+ */
  mod_v6nhg = &peer->nexthop.v6_global;
  gnh_modified = 1;
  } else if ((peer->sort == BGP_PEER_EBGP)
@@ -521,16 +524,30 @@ struct stream *bpacket_reformat_for_peer(struct bpacket *pkt,
  */
  mod_v6nhg = &peer->nexthop.v6_global;
  gnh_modified = 1;
+ } else if (IS_MAPPED_IPV6(&v6nhglobal) &&
+ !IN6_IS_ADDR_LINKLOCAL(&peer->nexthop.v6_global)) {
+ /* prefer a IPv6 native global address over
+ * an IPv4-mapped IPv6 address as nexthop when
+ * forwarding UPDATEs.
+ */
+ mod_v6nhg = &peer->nexthop.v6_global;
+ gnh_modified = 1;
  }
 
- if (IN6_IS_ADDR_UNSPECIFIED(mod_v6nhg)) {
- if (peer->nexthop.v4.s_addr != INADDR_ANY) {
- ipv4_to_ipv4_mapped_ipv6(mod_v6nhg,
- peer->nexthop.v4);
- }
+ if (!peer->conf_if && peer->nexthop.v4.s_addr != INADDR_ANY &&
+ (IN6_IS_ADDR_UNSPECIFIED(mod_v6nhg) ||
+ (IN6_IS_ADDR_LINKLOCAL(mod_v6nhg) &&
+ ((peer->connection->su.sa.sa_family == AF_INET6 && paf->afi == AFI_IP) ||
+ (peer->connection->su.sa.sa_family == AF_INET && paf->afi == AFI_IP6))))) {
+ ipv4_to_ipv4_mapped_ipv6(mod_v6nhg, peer->nexthop.v4);
+ gnh_modified = 1;
  }
 
  if (IS_MAPPED_IPV6(&peer->nexthop.v6_global)) {
+ /* If the interface to the peer has no global IPv6
+ * address, replace the nexthop in UPDATE with
+ * the IPv4-mapped IPv6 address if any.
+ */
  mod_v6nhg = &peer->nexthop.v6_global;
  gnh_modified = 1;
  }

bgpd/bgp_zebra.c

@@ -302,11 +302,12 @@ static int bgp_ifp_down(struct interface *ifp)
 
 static int bgp_interface_address_add(ZAPI_CALLBACK_ARGS)
 {
- struct connected *ifc;
+ struct connected *ifc, *connected;
  struct bgp *bgp;
  struct peer *peer;
  struct prefix *addr;
  struct listnode *node, *nnode;
+ bool v6_ll_in_nh_global;
  afi_t afi;
  safi_t safi;
 
@@ -324,56 +325,61 @@ static int bgp_interface_address_add(ZAPI_CALLBACK_ARGS)
  if (!bgp)
  return 0;
 
- if (if_is_operative(ifc->ifp)) {
- bgp_connected_add(bgp, ifc);
+ if (!if_is_operative(ifc->ifp))
+ return 0;
 
- /* If we have learnt of any neighbors on this interface,
- * check to kick off any BGP interface-based neighbors,
- * but only if this is a link-local address.
- */
- if (IN6_IS_ADDR_LINKLOCAL(&ifc->address->u.prefix6)
- && !list_isempty(ifc->ifp->nbr_connected))
- bgp_start_interface_nbrs(bgp, ifc->ifp);
- else {
- addr = ifc->address;
+ bgp_connected_add(bgp, ifc);
 
- for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer)) {
- if (addr->family == AF_INET)
- continue;
+ /* If we have learnt of any neighbors on this interface,
+ * check to kick off any BGP interface-based neighbors,
+ * but only if this is a link-local address.
+ */
+ if (IN6_IS_ADDR_LINKLOCAL(&ifc->address->u.prefix6) &&
+ !list_isempty(ifc->ifp->nbr_connected))
+ bgp_start_interface_nbrs(bgp, ifc->ifp);
+ else if (ifc->address->family == AF_INET6 &&
+ !IN6_IS_ADDR_LINKLOCAL(&ifc->address->u.prefix6)) {
+ addr = ifc->address;
 
- /*
- * If the Peer's interface name matches the
- * interface name for which BGP received the
- * update and if the received interface address
- * is a globalV6 and if the peer is currently
- * using a v4-mapped-v6 addr or a link local
- * address, then copy the Rxed global v6 addr
- * into peer's v6_global and send updates out
- * with new nexthop addr.
- */
- if ((peer->conf_if &&
- (strcmp(peer->conf_if, ifc->ifp->name) ==
- 0)) &&
- !IN6_IS_ADDR_LINKLOCAL(&addr->u.prefix6) &&
- ((IS_MAPPED_IPV6(
- &peer->nexthop.v6_global)) ||
- IN6_IS_ADDR_LINKLOCAL(
- &peer->nexthop.v6_global))) {
-
- if (bgp_debug_zebra(ifc->address)) {
- zlog_debug(
- "Update peer %pBP's current intf addr %pI6 and send updates",
- peer,
- &peer->nexthop
- .v6_global);
- }
- memcpy(&peer->nexthop.v6_global,
- &addr->u.prefix6,
- IPV6_MAX_BYTELEN);
- FOREACH_AFI_SAFI (afi, safi)
- bgp_announce_route(peer, afi,
- safi, true);
+ for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer)) {
+ v6_ll_in_nh_global = false;
+
+ if (IN6_IS_ADDR_LINKLOCAL(&peer->nexthop.v6_global)) {
+ frr_each (if_connected, ifc->ifp->connected, connected) {
+ if (connected->address->family != AF_INET6)
+ continue;
+ if (!IPV6_ADDR_SAME(&connected->address->u.prefix6,
+ &peer->nexthop.v6_global))
+ continue;
+ /* peer->nexthop.v6_global contains a link-local address
+ * that needs to be replaced by the global address.
+ */
+ v6_ll_in_nh_global = true;
+ break;
+ }
+ }
+
+ /*
+ * If the Peer's interface name matches the
+ * interface name for which BGP received the
+ * update and if the received interface address
+ * is a globalV6 and if the peer is currently
+ * using a v4-mapped-v6 addr or a link local
+ * address, then copy the Rxed global v6 addr
+ * into peer's v6_global and send updates out
+ * with new nexthop addr.
+ */
+ if (v6_ll_in_nh_global ||
+ (peer->conf_if && strcmp(peer->conf_if, ifc->ifp->name) == 0 &&
+ (IS_MAPPED_IPV6(&peer->nexthop.v6_global) ||
+ IN6_IS_ADDR_LINKLOCAL(&peer->nexthop.v6_global)))) {
+ if (bgp_debug_zebra(ifc->address)) {
+ zlog_debug("Update peer %pBP's current intf global addr from %pI6 to %pI6 and send updates",
+ peer, &peer->nexthop.v6_global, &addr->u.prefix6);
  }
+ memcpy(&peer->nexthop.v6_global, &addr->u.prefix6, IPV6_MAX_BYTELEN);
+ FOREACH_AFI_SAFI (afi, safi)
+ bgp_announce_route(peer, afi, safi, true);
  }
  }
  }
@@ -384,10 +390,14 @@ static int bgp_interface_address_add(ZAPI_CALLBACK_ARGS)
 static int bgp_interface_address_delete(ZAPI_CALLBACK_ARGS)
 {
  struct listnode *node, *nnode;
- struct connected *ifc;
+ struct connected *ifc, *connected;
  struct peer *peer;
  struct bgp *bgp;
  struct prefix *addr;
+ struct in6_addr *v6_global = NULL;
+ struct in6_addr *v6_local = NULL;
+ afi_t afi;
+ safi_t safi;
 
  bgp = bgp_lookup_by_vrf_id(vrf_id);
 
@@ -406,7 +416,17 @@ static int bgp_interface_address_delete(ZAPI_CALLBACK_ARGS)
 
  addr = ifc->address;
 
- if (bgp) {
+ if (bgp && addr->family == AF_INET6 && !IN6_IS_ADDR_LINKLOCAL(&addr->u.prefix6)) {
+ /* find another IPv6 global if possible and find the IPv6 link-local */
+ frr_each (if_connected, ifc->ifp->connected, connected) {
+ if (connected->address->family != AF_INET6)
+ continue;
+ if (IN6_IS_ADDR_LINKLOCAL(&connected->address->u.prefix6))
+ v6_local = &connected->address->u.prefix6;
+ else
+ v6_global = &connected->address->u.prefix6;
+ }
+
  /*
  * When we are using the v6 global as part of the peering
  * nexthops and we are removing it, then we need to
@@ -415,17 +435,13 @@ static int bgp_interface_address_delete(ZAPI_CALLBACK_ARGS)
  * we do not want the peering to bounce.
  */
  for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer)) {
- afi_t afi;
- safi_t safi;
-
- if (addr->family == AF_INET)
- continue;
-
- if (!IN6_IS_ADDR_LINKLOCAL(&addr->u.prefix6)
- && memcmp(&peer->nexthop.v6_global,
- &addr->u.prefix6, 16)
- == 0) {
- memset(&peer->nexthop.v6_global, 0, 16);
+ if (IPV6_ADDR_SAME(&peer->nexthop.v6_global, &addr->u.prefix6)) {
+ if (v6_global)
+ IPV6_ADDR_COPY(&peer->nexthop.v6_global, v6_global);
+ else if (v6_local)
+ IPV6_ADDR_COPY(&peer->nexthop.v6_global, v6_local);
+ else
+ memset(&peer->nexthop.v6_global, 0, IPV6_MAX_BYTELEN);
  FOREACH_AFI_SAFI (afi, safi)
  bgp_announce_route(peer, afi, safi,
  true);

tests/topotests/bgp_6vpe_ebgp_topo1/h1/zebra.conf

@@ -0,0 +1,4 @@
+ipv6 route fd00:200::/64 fd00:100::2
+interface eth-pe1
+ ipv6 address fd00:100::1/64
+!

tests/topotests/bgp_6vpe_ebgp_topo1/h2/zebra.conf

@@ -0,0 +1,8 @@
+ipv6 route fd00:100::/64 fd00:200::5
+interface eth-pe2
+ ipv6 address fd00:200::6/64
+ ipv6 address fd00:201::6/64
+ ipv6 address fd00:300::6/64
+ ipv6 address fd00:400::6/64
+ ipv6 address fd01:200::6/64
+!

tests/topotests/bgp_6vpe_ebgp_topo1/pe1/bgp_summary.json

@@ -0,0 +1,13 @@
+{
+ "ipv6Vpn": {
+ "routerId": "198.51.100.2",
+ "as": 65500,
+ "peers": {
+ "192.0.2.5": {
+ "remoteAs": 65501,
+ "state": "Established",
+ "peerState": "OK"
+ }
+ }
+ }
+}