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zebra: evpn: not coerce VTEP IP to IPv4 in nh_list

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In L3 BGP-EVPN, if there are both IPv4 and IPv6 routes in the VPN, zebra
maintains two instances of `struct zebra_neigh` object: one with IPv4
address of the nexthop, and another with IPv6 address that is an IPv4
mapped to IPv6, but only one intance of `struct zebra_mac` object, that
contains a list of nexthop addresses that use this mac.

The code in `zebra_vxlan` module uses the fact that the list is empty as
the indication that the `zebra_mac` object is unused, and needs to be
dropped. However, preexisting code used nexthop address converted to
IPv4 notation for the element of this list. As a result, when two
`zebra_neigh` objects, one IPv4 and one IPv6-mapped-IPv4 were linked to
the `zebra_mac` object, only one element was added to the list.
Consequently, when one of the two `zebra_neigh` objects was dropped, the
only element in the list was removed, making it empty, and `zebra_mac`
object was dropped, and neigbrour cache elements uninstalled from the
kernel.

As a result, after the last route in _one_ family was removed from a
remote vtep, all remaining routes in the _other_ family became
unreachable, because RMAC of the vtep was removed.

This commit makes `zebra_mac` use uncoerced IP address of the `zebra_neigh`
object for the entries in the `nh_list`. This way, `zebra_mac` object no
longer loses track of `zebra_neigh` objects that need it.

Bug-URL: https://github.com/FRRouting/frr/issues/16340
Signed-off-by: Eugene Crosser <crosser@average.org>
This commit is contained in:
Eugene Crosser 2024-07-02 19:02:53 +02:00
parent 66a84c7c10
commit f883c7119e
1 changed files with 34 additions and 44 deletions
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78
zebra/zebra_vxlan.c
View file

@ -1356,6 +1356,18 @@ static int zl3vni_remote_rmac_add(struct zebra_l3vni *zl3vni,
{
struct zebra_mac *zrmac = NULL;
struct ipaddr *vtep = NULL;
struct ipaddr ipv4_vtep;
/* vtep_ip may be v4 or v6-mapped-v4. But zrmac->fwd_info
* can only contain v4 version. So convert if needed
*/
memset(&ipv4_vtep, 0, sizeof(ipv4_vtep));
ipv4_vtep.ipa_type = IPADDR_V4;
if (vtep_ip->ipa_type == IPADDR_V6)
ipv4_mapped_ipv6_to_ipv4(&vtep_ip->ipaddr_v6,
&(ipv4_vtep.ipaddr_v4));
else
IPV4_ADDR_COPY(&(ipv4_vtep.ipaddr_v4), &vtep_ip->ipaddr_v4);
zrmac = zl3vni_rmac_lookup(zl3vni, rmac);
if (!zrmac) {
@ -1369,7 +1381,7 @@ static int zl3vni_remote_rmac_add(struct zebra_l3vni *zl3vni,
return -1;
}
memset(&zrmac->fwd_info, 0, sizeof(zrmac->fwd_info));
zrmac->fwd_info.r_vtep_ip = vtep_ip->ipaddr_v4;
zrmac->fwd_info.r_vtep_ip = ipv4_vtep.ipaddr_v4;
vtep = XCALLOC(MTYPE_EVPN_VTEP, sizeof(struct ipaddr));
memcpy(vtep, vtep_ip, sizeof(struct ipaddr));
@ -1383,14 +1395,14 @@ static int zl3vni_remote_rmac_add(struct zebra_l3vni *zl3vni,
/* install rmac in kernel */
zl3vni_rmac_install(zl3vni, zrmac);
} else if (!IPV4_ADDR_SAME(&zrmac->fwd_info.r_vtep_ip,
&vtep_ip->ipaddr_v4)) {
&(ipv4_vtep.ipaddr_v4))) {
if (IS_ZEBRA_DEBUG_VXLAN)
zlog_debug(
"L3VNI %u Remote VTEP change(%pI4 -> %pIA) for RMAC %pEA",
zl3vni->vni, &zrmac->fwd_info.r_vtep_ip,
vtep_ip, rmac);
zrmac->fwd_info.r_vtep_ip = vtep_ip->ipaddr_v4;
zrmac->fwd_info.r_vtep_ip = ipv4_vtep.ipaddr_v4;
vtep = XCALLOC(MTYPE_EVPN_VTEP, sizeof(struct ipaddr));
memcpy(vtep, vtep_ip, sizeof(struct ipaddr));
@ -1410,36 +1422,29 @@ static void zl3vni_remote_rmac_del(struct zebra_l3vni *zl3vni,
struct zebra_mac *zrmac,
struct ipaddr *vtep_ip)
{
struct ipaddr ipv4_vtep;
if (!zl3vni_nh_lookup(zl3vni, vtep_ip)) {
memset(&ipv4_vtep, 0, sizeof(ipv4_vtep));
ipv4_vtep.ipa_type = IPADDR_V4;
if (vtep_ip->ipa_type == IPADDR_V6)
ipv4_mapped_ipv6_to_ipv4(&vtep_ip->ipaddr_v6,
&ipv4_vtep.ipaddr_v4);
else
memcpy(&(ipv4_vtep.ipaddr_v4), &vtep_ip->ipaddr_v4,
sizeof(struct in_addr));
/* remove nh from rmac's list */
l3vni_rmac_nh_list_nh_delete(zl3vni, zrmac, &ipv4_vtep);
/* delete nh is same as current selected, fall back to
* one present in the list
*/
if (IPV4_ADDR_SAME(&zrmac->fwd_info.r_vtep_ip,
&ipv4_vtep.ipaddr_v4) &&
listcount(zrmac->nh_list)) {
l3vni_rmac_nh_list_nh_delete(zl3vni, zrmac, vtep_ip);
/* If there are remaining entries, use IPv4 from one */
if (listcount(zrmac->nh_list)) {
struct ipaddr *vtep;
struct ipaddr ipv4_vtep;
vtep = listgetdata(listhead(zrmac->nh_list));
zrmac->fwd_info.r_vtep_ip = vtep->ipaddr_v4;
memset(&ipv4_vtep, 0, sizeof(ipv4_vtep));
ipv4_vtep.ipa_type = IPADDR_V4;
if (vtep->ipa_type == IPADDR_V6)
ipv4_mapped_ipv6_to_ipv4(&vtep->ipaddr_v6,
&(ipv4_vtep.ipaddr_v4));
else
IPV4_ADDR_COPY(&(ipv4_vtep.ipaddr_v4),
&vtep->ipaddr_v4);
zrmac->fwd_info.r_vtep_ip = ipv4_vtep.ipaddr_v4;
if (IS_ZEBRA_DEBUG_VXLAN)
zlog_debug(
"L3VNI %u Remote VTEP nh change(%pIA -> %pI4) for RMAC %pEA",
zl3vni->vni, &ipv4_vtep,
&zrmac->fwd_info.r_vtep_ip,
&zrmac->macaddr);
zlog_debug("L3VNI %u Remote VTEP nh change(%pIA -> %pI4) for RMAC %pEA",
zl3vni->vni, vtep_ip,
&zrmac->fwd_info.r_vtep_ip,
&zrmac->macaddr);
/* install rmac in kernel */
zl3vni_rmac_install(zl3vni, zrmac);
@ -2531,7 +2536,6 @@ void zebra_vxlan_evpn_vrf_route_add(vrf_id_t vrf_id, const struct ethaddr *rmac,
const struct prefix *host_prefix)
{
struct zebra_l3vni *zl3vni = NULL;
struct ipaddr ipv4_vtep;
zl3vni = zl3vni_from_vrf(vrf_id);
if (!zl3vni || !is_l3vni_oper_up(zl3vni))
@ -2547,24 +2551,10 @@ void zebra_vxlan_evpn_vrf_route_add(vrf_id_t vrf_id, const struct ethaddr *rmac,
svd_remote_nh_add(zl3vni, vtep_ip, rmac, host_prefix);
/*
* if the remote vtep is a ipv4 mapped ipv6 address convert it to ipv4
* address. Rmac is programmed against the ipv4 vtep because we only
* support ipv4 tunnels in the h/w right now
*/
memset(&ipv4_vtep, 0, sizeof(ipv4_vtep));
ipv4_vtep.ipa_type = IPADDR_V4;
if (vtep_ip->ipa_type == IPADDR_V6)
ipv4_mapped_ipv6_to_ipv4(&vtep_ip->ipaddr_v6,
&(ipv4_vtep.ipaddr_v4));
else
memcpy(&(ipv4_vtep.ipaddr_v4), &vtep_ip->ipaddr_v4,
sizeof(struct in_addr));
/*
* add the rmac - remote rmac to be installed is against the ipv4
* add the rmac - remote rmac to be installed is against the
* nexthop address
*/
zl3vni_remote_rmac_add(zl3vni, rmac, &ipv4_vtep);
zl3vni_remote_rmac_add(zl3vni, rmac, vtep_ip);
}
/* handle evpn vrf route delete */