From: Petr Machata petrm@nvidia.com
[ Upstream commit d42d543368343c0449a4e433b5f02e063a86209c ]
When a vxlan netdevice is brought up, if its default remote is a multicast address, the device joins the indicated group.
Therefore when the multicast remote address changes, the device should leave the current group and subscribe to the new one. Similarly when the interface used for endpoint communication is changed in a situation when multicast remote is configured. This is currently not done.
Both vxlan_igmp_join() and vxlan_igmp_leave() can however fail. So it is possible that with such fix, the netdevice will end up in an inconsistent situation where the old group is not joined anymore, but joining the new group fails. Should we join the new group first, and leave the old one second, we might end up in the opposite situation, where both groups are joined. Undoing any of this during rollback is going to be similarly problematic.
One solution would be to just forbid the change when the netdevice is up. However in vnifilter mode, changing the group address is allowed, and these problems are simply ignored (see vxlan_vni_update_group()):
# ip link add name br up type bridge vlan_filtering 1 # ip link add vx1 up master br type vxlan external vnifilter local 192.0.2.1 dev lo dstport 4789 # bridge vni add dev vx1 vni 200 group 224.0.0.1 # tcpdump -i lo & # bridge vni add dev vx1 vni 200 group 224.0.0.2 18:55:46.523438 IP 0.0.0.0 > 224.0.0.22: igmp v3 report, 1 group record(s) 18:55:46.943447 IP 0.0.0.0 > 224.0.0.22: igmp v3 report, 1 group record(s) # bridge vni dev vni group/remote vx1 200 224.0.0.2
Having two different modes of operation for conceptually the same interface is silly, so in this patch, just do what the vnifilter code does and deal with the errors by crossing fingers real hard.
The vnifilter code leaves old before joining new, and in case of join / leave failures does not roll back the configuration changes that have already been applied, but bails out of joining if it could not leave. Do the same here: leave before join, apply changes unconditionally and do not attempt to join if we couldn't leave.
Signed-off-by: Petr Machata petrm@nvidia.com Reviewed-by: Ido Schimmel idosch@nvidia.com Reviewed-by: Nikolay Aleksandrov razor@blackwall.org Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/vxlan/vxlan_core.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c index 64db3e98a1b66..822cf49d82676 100644 --- a/drivers/net/vxlan/vxlan_core.c +++ b/drivers/net/vxlan/vxlan_core.c @@ -4240,6 +4240,7 @@ static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[], struct netlink_ext_ack *extack) { struct vxlan_dev *vxlan = netdev_priv(dev); + bool rem_ip_changed, change_igmp; struct net_device *lowerdev; struct vxlan_config conf; struct vxlan_rdst *dst; @@ -4263,8 +4264,13 @@ static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[], if (err) return err;
+ rem_ip_changed = !vxlan_addr_equal(&conf.remote_ip, &dst->remote_ip); + change_igmp = vxlan->dev->flags & IFF_UP && + (rem_ip_changed || + dst->remote_ifindex != conf.remote_ifindex); + /* handle default dst entry */ - if (!vxlan_addr_equal(&conf.remote_ip, &dst->remote_ip)) { + if (rem_ip_changed) { u32 hash_index = fdb_head_index(vxlan, all_zeros_mac, conf.vni);
spin_lock_bh(&vxlan->hash_lock[hash_index]); @@ -4308,6 +4314,9 @@ static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[], } }
+ if (change_igmp && vxlan_addr_multicast(&dst->remote_ip)) + err = vxlan_multicast_leave(vxlan); + if (conf.age_interval != vxlan->cfg.age_interval) mod_timer(&vxlan->age_timer, jiffies);
@@ -4315,7 +4324,12 @@ static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[], if (lowerdev && lowerdev != dst->remote_dev) dst->remote_dev = lowerdev; vxlan_config_apply(dev, &conf, lowerdev, vxlan->net, true); - return 0; + + if (!err && change_igmp && + vxlan_addr_multicast(&dst->remote_ip)) + err = vxlan_multicast_join(vxlan); + + return err; }
static void vxlan_dellink(struct net_device *dev, struct list_head *head)