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rtnetlink: bridge: mcast: Relax group address validation in common code 

In the upcoming VXLAN MDB implementation, the 0.0.0.0 and :: MDB entries
will act as catchall entries for unregistered IP multicast traffic in a
similar fashion to the 00:00:00:00:00:00 VXLAN FDB entry that is used to
transmit BUM traffic.

In deployments where inter-subnet multicast forwarding is used, not all
the VTEPs in a tenant domain are members in all the broadcast domains.
It is therefore advantageous to transmit BULL (broadcast, unknown
unicast and link-local multicast) and unregistered IP multicast traffic
on different tunnels. If the same tunnel was used, a VTEP only
interested in IP multicast traffic would also pull all the BULL traffic
and drop it as it is not a member in the originating broadcast domain
[1].

Prepare for this change by allowing the 0.0.0.0 group address in the
common rtnetlink MDB code and forbid it in the bridge driver. A similar
change is not needed for IPv6 because the common code only validates
that the group address is not the all-nodes address.

[1] https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-mcast#section-2.6

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ido Schimmel 2023-03-15 15:11:48 +02:00 committed by David S. Miller
parent cc7f5022f8
commit da654c80a0
2 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
net/bridge/br_mdb.c
View File

@ -1246,6 +1246,12 @@ static int br_mdb_config_init(struct br_mdb_config *cfg, struct net_device *dev,
}
}
if (cfg->entry->addr.proto == htons(ETH_P_IP) &&
ipv4_is_zeronet(cfg->entry->addr.u.ip4)) {
NL_SET_ERR_MSG_MOD(extack, "IPv4 entry group address 0.0.0.0 is not allowed");
return -EINVAL;
}
if (tb[MDBA_SET_ENTRY_ATTRS])
return br_mdb_config_attrs_init(tb[MDBA_SET_ENTRY_ATTRS], cfg,
extack);

5
net/core/rtnetlink.c
View File

@ -6152,8 +6152,9 @@ static int rtnl_validate_mdb_entry(const struct nlattr *attr,
}
if (entry->addr.proto == htons(ETH_P_IP)) {
if (!ipv4_is_multicast(entry->addr.u.ip4)) {
NL_SET_ERR_MSG(extack, "IPv4 entry group address is not multicast");
if (!ipv4_is_multicast(entry->addr.u.ip4) &&
!ipv4_is_zeronet(entry->addr.u.ip4)) {
NL_SET_ERR_MSG(extack, "IPv4 entry group address is not multicast or 0.0.0.0");
return -EINVAL;
}
if (ipv4_is_local_multicast(entry->addr.u.ip4)) {