genetlink: make multicast groups const, prevent abuse

Register generic netlink multicast groups as an array with
the family and give them contiguous group IDs. Then instead
of passing the global group ID to the various functions that
send messages, pass the ID relative to the family - for most
families that's just 0 because the only have one group.

This avoids the list_head and ID in each group, adding a new
field for the mcast group ID offset to the family.

At the same time, this allows us to prevent abusing groups
again like the quota and dropmon code did, since we can now
check that a family only uses a group it owns.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 17 deletions

diff --git a/net/ieee802154/netlink.c b/net/ieee802154/netlink.c
index 5172f467a383..43f1b2bf469f 100644
--- a/net/ieee802154/netlink.c
+++ b/net/ieee802154/netlink.c
@@ -125,25 +125,17 @@ static const struct genl_ops ieee8021154_ops[] = {
 			ieee802154_dump_iface),
 };
 
-int __init ieee802154_nl_init(void)
-{
-	int rc;
-
-	rc = genl_register_family_with_ops(&nl802154_family, ieee8021154_ops);
-	if (rc)
-		return rc;
+static const struct genl_multicast_group ieee802154_mcgrps[] = {
+	[IEEE802154_COORD_MCGRP] = { .name = IEEE802154_MCAST_COORD_NAME, },
+	[IEEE802154_BEACON_MCGRP] = { .name = IEEE802154_MCAST_BEACON_NAME, },
+};
 
-	rc = genl_register_mc_group(&nl802154_family, &ieee802154_coord_mcgrp);
-	if (rc)
-		goto fail;
 
-	rc = genl_register_mc_group(&nl802154_family, &ieee802154_beacon_mcgrp);
-	if (rc)
-		goto fail;
-	return 0;
-fail:
-	genl_unregister_family(&nl802154_family);
-	return rc;
+int __init ieee802154_nl_init(void)
+{
+	return genl_register_family_with_ops_groups(&nl802154_family,
+						    ieee8021154_ops,
+						    ieee802154_mcgrps);
 }
 
 void __exit ieee802154_nl_exit(void)