diff mbox series

[net-next,v2,04/11] rtnetlink: bridge: mcast: Relax group address validation in common code

Message ID 20230315131155.4071175-5-idosch@nvidia.com (mailing list archive)
State Accepted
Commit da654c80a0ebba2e2a0614e017c9bbe57f643fe2
Delegated to: Netdev Maintainers
Headers show
Series vxlan: Add MDB support | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 20 this patch: 20
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 20 this patch: 20
netdev/checkpatch warning WARNING: line length of 103 exceeds 80 columns WARNING: line length of 94 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Ido Schimmel March 15, 2023, 1:11 p.m. UTC 
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>
---
 net/bridge/br_mdb.c  | 6 ++++++
 net/core/rtnetlink.c | 5 +++--
 2 files changed, 9 insertions(+), 2 deletions(-)
diff mbox series

Patch

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)) {