Skip to content

Commit

Permalink
net: switchdev: fix FDB entries towards foreign ports not getting pro…
Browse files Browse the repository at this point in the history 
…pagated to us

The newly introduced switchdev_handle_fdb_{add,del}_to_device helpers
solved a problem but introduced another one. They have a severe design
bug: they do not propagate FDB events on foreign interfaces to us, i.e.
this use case:

         br0
        /   \
       /     \
      /       \
     /         \
   swp0       eno0
(switchdev)  (foreign)

when an address is learned on eno0, what is supposed to happen is that
this event should also be propagated towards swp0. Somehow I managed to
convince myself that this did work correctly, but obviously it does not.

The trouble with foreign interfaces is that we must reach a switchdev
net_device pointer through a foreign net_device that has no direct
upper/lower relationship with it. So we need to do exploratory searching
through the lower interfaces of the foreign net_device's bridge upper
(to reach swp0 from eno0, we must check its upper, br0, for lower
interfaces that pass the check_cb and foreign_dev_check_cb). This is
something that the previous code did not do, it just assumed that "dev"
will become a switchdev interface at some point, somehow, probably by
magic.

With this patch, assisted address learning on the CPU port works again
in DSA:

ip link add br0 type bridge
ip link set swp0 master br0
ip link set eno0 master br0
ip link set br0 up

[   46.708929] mscc_felix 0000:00:00.5 swp0: Adding FDB entry towards eno0, addr 00:04:9f:05:f4:ab vid 0 as host address

Fixes: 8ca0717 ("net: switchdev: introduce a fanout helper for SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE")
Reported-by: Eric Woudstra <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
  • Loading branch information
@vladimiroltean @davem330
vladimiroltean authored and davem330 committed Jul 22, 2021
1 parent f796fcd commit 2b0a568
Showing 1 changed file with 142 additions and 72 deletions.
214 changes: 142 additions & 72 deletions net/switchdev/switchdev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -378,6 +378,56 @@ int call_switchdev_blocking_notifiers(unsigned long val, struct net_device *dev,
}
EXPORT_SYMBOL_GPL(call_switchdev_blocking_notifiers);

struct switchdev_nested_priv {
bool (*check_cb)(const struct net_device *dev);
bool (*foreign_dev_check_cb)(const struct net_device *dev,
const struct net_device *foreign_dev);
const struct net_device *dev;
struct net_device *lower_dev;
};

static int switchdev_lower_dev_walk(struct net_device *lower_dev,
struct netdev_nested_priv *priv)
{
struct switchdev_nested_priv *switchdev_priv = priv->data;
bool (*foreign_dev_check_cb)(const struct net_device *dev,
const struct net_device *foreign_dev);
bool (*check_cb)(const struct net_device *dev);
const struct net_device *dev;

check_cb = switchdev_priv->check_cb;
foreign_dev_check_cb = switchdev_priv->foreign_dev_check_cb;
dev = switchdev_priv->dev;

if (check_cb(lower_dev) && !foreign_dev_check_cb(lower_dev, dev)) {
switchdev_priv->lower_dev = lower_dev;
return 1;
}

return 0;
}

static struct net_device *
switchdev_lower_dev_find(struct net_device *dev,
bool (*check_cb)(const struct net_device *dev),
bool (*foreign_dev_check_cb)(const struct net_device *dev,
const struct net_device *foreign_dev))
{
struct switchdev_nested_priv switchdev_priv = {
.check_cb = check_cb,
.foreign_dev_check_cb = foreign_dev_check_cb,
.dev = dev,
.lower_dev = NULL,
};
struct netdev_nested_priv priv = {
.data = &switchdev_priv,
};

netdev_walk_all_lower_dev_rcu(dev, switchdev_lower_dev_walk, &priv);

return switchdev_priv.lower_dev;
}

static int __switchdev_handle_fdb_add_to_device(struct net_device *dev,
const struct net_device *orig_dev,
const struct switchdev_notifier_fdb_info *fdb_info,
Expand All @@ -392,37 +442,18 @@ static int __switchdev_handle_fdb_add_to_device(struct net_device *dev,
const struct switchdev_notifier_fdb_info *fdb_info))
{
const struct switchdev_notifier_info *info = &fdb_info->info;
struct net_device *lower_dev;
struct net_device *br, *lower_dev;
struct list_head *iter;
int err = -EOPNOTSUPP;

if (check_cb(dev)) {
/* Handle FDB entries on foreign interfaces as FDB entries
* towards the software bridge.
*/
if (foreign_dev_check_cb && foreign_dev_check_cb(dev, orig_dev)) {
struct net_device *br = netdev_master_upper_dev_get_rcu(dev);

if (!br || !netif_is_bridge_master(br))
return 0;

/* No point in handling FDB entries on a foreign bridge */
if (foreign_dev_check_cb(dev, br))
return 0;

return __switchdev_handle_fdb_add_to_device(br, orig_dev,
fdb_info, check_cb,
foreign_dev_check_cb,
add_cb, lag_add_cb);
}

if (check_cb(dev))
return add_cb(dev, orig_dev, info->ctx, fdb_info);
}

/* If we passed over the foreign check, it means that the LAG interface
* is offloaded.
*/
if (netif_is_lag_master(dev)) {
if (!switchdev_lower_dev_find(dev, check_cb, foreign_dev_check_cb))
goto maybe_bridged_with_us;

/* This is a LAG interface that we offload */
if (!lag_add_cb)
return -EOPNOTSUPP;

Expand All @@ -432,20 +463,49 @@ static int __switchdev_handle_fdb_add_to_device(struct net_device *dev,
/* Recurse through lower interfaces in case the FDB entry is pointing
* towards a bridge device.
*/
netdev_for_each_lower_dev(dev, lower_dev, iter) {
/* Do not propagate FDB entries across bridges */
if (netif_is_bridge_master(lower_dev))
continue;
if (netif_is_bridge_master(dev)) {
if (!switchdev_lower_dev_find(dev, check_cb, foreign_dev_check_cb))
return 0;

/* This is a bridge interface that we offload */
netdev_for_each_lower_dev(dev, lower_dev, iter) {
/* Do not propagate FDB entries across bridges */
if (netif_is_bridge_master(lower_dev))
continue;

/* Bridge ports might be either us, or LAG interfaces
* that we offload.
*/
if (!check_cb(lower_dev) &&
!switchdev_lower_dev_find(lower_dev, check_cb,
foreign_dev_check_cb))
continue;

err = __switchdev_handle_fdb_add_to_device(lower_dev, orig_dev,
fdb_info, check_cb,
foreign_dev_check_cb,
add_cb, lag_add_cb);
if (err && err != -EOPNOTSUPP)
return err;
}

err = __switchdev_handle_fdb_add_to_device(lower_dev, orig_dev,
fdb_info, check_cb,
foreign_dev_check_cb,
add_cb, lag_add_cb);
if (err && err != -EOPNOTSUPP)
return err;
return 0;
}

return err;
maybe_bridged_with_us:
/* Event is neither on a bridge nor a LAG. Check whether it is on an
* interface that is in a bridge with us.
*/
br = netdev_master_upper_dev_get_rcu(dev);
if (!br || !netif_is_bridge_master(br))
return 0;

if (!switchdev_lower_dev_find(br, check_cb, foreign_dev_check_cb))
return 0;

return __switchdev_handle_fdb_add_to_device(br, orig_dev, fdb_info,
check_cb, foreign_dev_check_cb,
add_cb, lag_add_cb);
}

int switchdev_handle_fdb_add_to_device(struct net_device *dev,
Expand Down Expand Up @@ -487,37 +547,18 @@ static int __switchdev_handle_fdb_del_to_device(struct net_device *dev,
const struct switchdev_notifier_fdb_info *fdb_info))
{
const struct switchdev_notifier_info *info = &fdb_info->info;
struct net_device *lower_dev;
struct net_device *br, *lower_dev;
struct list_head *iter;
int err = -EOPNOTSUPP;

if (check_cb(dev)) {
/* Handle FDB entries on foreign interfaces as FDB entries
* towards the software bridge.
*/
if (foreign_dev_check_cb && foreign_dev_check_cb(dev, orig_dev)) {
struct net_device *br = netdev_master_upper_dev_get_rcu(dev);

if (!br || !netif_is_bridge_master(br))
return 0;

/* No point in handling FDB entries on a foreign bridge */
if (foreign_dev_check_cb(dev, br))
return 0;

return __switchdev_handle_fdb_del_to_device(br, orig_dev,
fdb_info, check_cb,
foreign_dev_check_cb,
del_cb, lag_del_cb);
}

if (check_cb(dev))
return del_cb(dev, orig_dev, info->ctx, fdb_info);
}

/* If we passed over the foreign check, it means that the LAG interface
* is offloaded.
*/
if (netif_is_lag_master(dev)) {
if (!switchdev_lower_dev_find(dev, check_cb, foreign_dev_check_cb))
goto maybe_bridged_with_us;

/* This is a LAG interface that we offload */
if (!lag_del_cb)
return -EOPNOTSUPP;

Expand All @@ -527,20 +568,49 @@ static int __switchdev_handle_fdb_del_to_device(struct net_device *dev,
/* Recurse through lower interfaces in case the FDB entry is pointing
* towards a bridge device.
*/
netdev_for_each_lower_dev(dev, lower_dev, iter) {
/* Do not propagate FDB entries across bridges */
if (netif_is_bridge_master(lower_dev))
continue;
if (netif_is_bridge_master(dev)) {
if (!switchdev_lower_dev_find(dev, check_cb, foreign_dev_check_cb))
return 0;

/* This is a bridge interface that we offload */
netdev_for_each_lower_dev(dev, lower_dev, iter) {
/* Do not propagate FDB entries across bridges */
if (netif_is_bridge_master(lower_dev))
continue;

/* Bridge ports might be either us, or LAG interfaces
* that we offload.
*/
if (!check_cb(lower_dev) &&
!switchdev_lower_dev_find(lower_dev, check_cb,
foreign_dev_check_cb))
continue;

err = __switchdev_handle_fdb_del_to_device(lower_dev, orig_dev,
fdb_info, check_cb,
foreign_dev_check_cb,
del_cb, lag_del_cb);
if (err && err != -EOPNOTSUPP)
return err;
}

err = __switchdev_handle_fdb_del_to_device(lower_dev, orig_dev,
fdb_info, check_cb,
foreign_dev_check_cb,
del_cb, lag_del_cb);
if (err && err != -EOPNOTSUPP)
return err;
return 0;
}

return err;
maybe_bridged_with_us:
/* Event is neither on a bridge nor a LAG. Check whether it is on an
* interface that is in a bridge with us.
*/
br = netdev_master_upper_dev_get_rcu(dev);
if (!br || !netif_is_bridge_master(br))
return 0;

if (!switchdev_lower_dev_find(br, check_cb, foreign_dev_check_cb))
return 0;

return __switchdev_handle_fdb_del_to_device(br, orig_dev, fdb_info,
check_cb, foreign_dev_check_cb,
del_cb, lag_del_cb);
}

int switchdev_handle_fdb_del_to_device(struct net_device *dev,
Expand Down

0 comments on commit 2b0a568

Please sign in to comment.