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@xxxxxxxxxx> Reviewed-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx> --- net/bridge/br_mdb.c | 6 ++++++ net/core/rtnetlink.c | 5 +++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c index 76636c61db21..7305f5f8215c 100644 --- a/net/bridge/br_mdb.c +++ b/net/bridge/br_mdb.c @@ -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); diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index f347d9fa78c7..b7b1661d0d56 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -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)) { -- 2.37.3
