The NS for DAD are sent on admin up as long as a valid qdisc is found. A race condition exists by which these packets will not egress the interface if the operational state of the lower device is not yet up. The solution is to delay DAD until the link is operationally up according to RFC2863. Rather than only doing this, follow the existing code checks by deferring IPv6 device initialization altogether. The fix allows DAD on devices like tunnels that are controlled by userspace control plane. The fix has no impact on regular deployments, but means that there is no IPv6 connectivity until the port has been opened in the case of port-based network access control, which should be desirable.
Unified · Split
| @@ -303,10 +303,10 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { · 302 unmodified lines | ||
| 303 | 303 | .disable_policy = 0, |
| 304 | 304 | }; |
| 305 | 305 | |
| 306 | −/* Check if a valid qdisc is available */ | |
| 307 | −static inline bool addrconf_qdisc_ok(const struct net_device *dev) | |
| 306 | +/* Check if link is ready: is it up and is a valid qdisc available */ | |
| 307 | +static inline bool addrconf_link_ready(const struct net_device *dev) | |
| 308 | 308 | { |
| 309 | − return !qdisc_tx_is_noop(dev); | |
| 309 | + return netif_oper_up(dev) && !qdisc_tx_is_noop(dev); | |
| 310 | 310 | } |
| 311 | 311 | |
| 312 | 312 | static void addrconf_del_rs_timer(struct inet6_dev *idev) |
| @@ -451,7 +451,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev) · 138 unmodified lines | ||
| 451 | 451 | |
| 452 | 452 | ndev->token = in6addr_any; |
| 453 | 453 | |
| 454 | − if (netif_running(dev) && addrconf_qdisc_ok(dev)) | |
| 454 | + if (netif_running(dev) && addrconf_link_ready(dev)) | |
| 455 | 455 | ndev->if_flags |= IF_READY; |
| 456 | 456 | |
| 457 | 457 | ipv6_mc_init_dev(ndev); |
| @@ -3403,7 +3403,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, · 2945 unmodified lines | ||
| 3403 | 3403 | /* restore routes for permanent addresses */ |
| 3404 | 3404 | addrconf_permanent_addr(dev); |
| 3405 | 3405 | |
| 3406 | − if (!addrconf_qdisc_ok(dev)) { | |
| 3406 | + if (!addrconf_link_ready(dev)) { | |
| 3407 | 3407 | /* device is not ready yet. */ |
| 3408 | 3408 | pr_info("ADDRCONF(NETDEV_UP): %s: link is not ready\n", |
| 3409 | 3409 | dev->name); |
| @@ -3418,7 +3418,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, · 8 unmodified lines | ||
| 3418 | 3418 | run_pending = 1; |
| 3419 | 3419 | } |
| 3420 | 3420 | } else if (event == NETDEV_CHANGE) { |
| 3421 | − if (!addrconf_qdisc_ok(dev)) { | |
| 3421 | + if (!addrconf_link_ready(dev)) { | |
| 3422 | 3422 | /* device is still not ready. */ |
| 3423 | 3423 | break; |
| 3424 | 3424 | } |