devlink: disallow reload operation during device cleanup

There is a race between driver code that does setup/cleanup of device
and devlink reload operation that in some drivers works with the same
code. Use after free could we easily obtained by running:

while true; do
        echo 10 > /sys/bus/netdevsim/new_device
        devlink dev reload netdevsim/netdevsim10 &
        echo 10 > /sys/bus/netdevsim/del_device
done

Fix this by enabling reload only after setup of device is complete and
disabling it at the beginning of the cleanup process.

Reported-by: Ido Schimmel <idosch@mellanox.com>
Fixes: 2d8dc5bbf4e7 ("devlink: Add support for reload")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
index 22c72fb7206afe8c50beff30501d38f41137e526..77f056b0895e6596156546fca860613291fbe942 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/main.c
@@ -4015,6 +4015,7 @@ static int mlx4_init_one(struct pci_dev *pdev, const struct pci_device_id *id)
                goto err_params_unregister;
 
        devlink_params_publish(devlink);
+       devlink_reload_enable(devlink);
        pci_save_state(pdev);
        return 0;
 
@@ -4126,6 +4127,8 @@ static void mlx4_remove_one(struct pci_dev *pdev)
        struct devlink *devlink = priv_to_devlink(priv);
        int active_vfs = 0;
 
+       devlink_reload_disable(devlink);
+
        if (mlx4_is_slave(dev))
                persist->interface_state |= MLX4_INTERFACE_STATE_NOWAIT;
 

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core.c b/drivers/net/ethernet/mellanox/mlxsw/core.c
index e1a90f5bddd040158cdd2c1c7f956bb848ea6e2d..da436a6aad2fb1a41725940555421c719cf7594a 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlxsw/core.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core.c
@@ -1198,8 +1198,10 @@ __mlxsw_core_bus_device_register(const struct mlxsw_bus_info *mlxsw_bus_info,
        if (err)
                goto err_thermal_init;
 
-       if (mlxsw_driver->params_register)
+       if (mlxsw_driver->params_register) {
                devlink_params_publish(devlink);
+               devlink_reload_enable(devlink);
+       }
 
        return 0;
 
@@ -1263,6 +1265,8 @@ void mlxsw_core_bus_device_unregister(struct mlxsw_core *mlxsw_core,
 {
        struct devlink *devlink = priv_to_devlink(mlxsw_core);
 
+       if (!reload)
+               devlink_reload_disable(devlink);
        if (devlink_is_reload_failed(devlink)) {
                if (!reload)
                        /* Only the parts that were not de-initialized in the

diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index 3da96c7e82655e5d73b2ce5ed02a3f5a705458d9..059711edfc61e9d8119d1a35afc7b0dc468f9ed2 100644 (file)
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -820,6 +820,7 @@ int nsim_dev_probe(struct nsim_bus_dev *nsim_bus_dev)
                goto err_bpf_dev_exit;
 
        devlink_params_publish(devlink);
+       devlink_reload_enable(devlink);
        return 0;
 
 err_bpf_dev_exit:
@@ -865,6 +866,8 @@ void nsim_dev_remove(struct nsim_bus_dev *nsim_bus_dev)
        struct nsim_dev *nsim_dev = dev_get_drvdata(&nsim_bus_dev->dev);
        struct devlink *devlink = priv_to_devlink(nsim_dev);
 
+       devlink_reload_disable(devlink);
+
        nsim_dev_reload_destroy(nsim_dev);
 
        nsim_bpf_dev_exit(nsim_dev);

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 8d6b5846822c731a56d262d250cc0019d48d46e2..7891611868e45ac05da8ac71fe1dbb0c1cfbb32a 100644 (file)
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -38,8 +38,9 @@ struct devlink {
        struct device *dev;
        possible_net_t _net;
        struct mutex lock;
-       bool reload_failed;
-       bool registered;
+       u8 reload_failed:1,
+          reload_enabled:1,
+          registered:1;
        char priv[0] __aligned(NETDEV_ALIGN);
 };
 
@@ -824,6 +825,8 @@ void devlink_net_set(struct devlink *devlink, struct net *net);
 struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size);
 int devlink_register(struct devlink *devlink, struct device *dev);
 void devlink_unregister(struct devlink *devlink);
+void devlink_reload_enable(struct devlink *devlink);
+void devlink_reload_disable(struct devlink *devlink);
 void devlink_free(struct devlink *devlink);
 int devlink_port_register(struct devlink *devlink,
                          struct devlink_port *devlink_port,

diff --git a/net/core/devlink.c b/net/core/devlink.c
index ff53f7d29dea90376ce6a30298d48d42b252fc03..2e027c9436e02e76015555033ce7c964044b94d4 100644 (file)
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -2791,6 +2791,9 @@ static int devlink_reload(struct devlink *devlink, struct net *dest_net,
 {
        int err;
 
+       if (!devlink->reload_enabled)
+               return -EOPNOTSUPP;
+
        err = devlink->ops->reload_down(devlink, !!dest_net, extack);
        if (err)
                return err;
@@ -6308,12 +6311,49 @@ EXPORT_SYMBOL_GPL(devlink_register);
 void devlink_unregister(struct devlink *devlink)
 {
        mutex_lock(&devlink_mutex);
+       WARN_ON(devlink_reload_supported(devlink) &&
+               devlink->reload_enabled);
        devlink_notify(devlink, DEVLINK_CMD_DEL);
        list_del(&devlink->list);
        mutex_unlock(&devlink_mutex);
 }
 EXPORT_SYMBOL_GPL(devlink_unregister);
 
+/**
+ *     devlink_reload_enable - Enable reload of devlink instance
+ *
+ *     @devlink: devlink
+ *
+ *     Should be called at end of device initialization
+ *     process when reload operation is supported.
+ */
+void devlink_reload_enable(struct devlink *devlink)
+{
+       mutex_lock(&devlink_mutex);
+       devlink->reload_enabled = true;
+       mutex_unlock(&devlink_mutex);
+}
+EXPORT_SYMBOL_GPL(devlink_reload_enable);
+
+/**
+ *     devlink_reload_disable - Disable reload of devlink instance
+ *
+ *     @devlink: devlink
+ *
+ *     Should be called at the beginning of device cleanup
+ *     process when reload operation is supported.
+ */
+void devlink_reload_disable(struct devlink *devlink)
+{
+       mutex_lock(&devlink_mutex);
+       /* Mutex is taken which ensures that no reload operation is in
+        * progress while setting up forbidded flag.
+        */
+       devlink->reload_enabled = false;
+       mutex_unlock(&devlink_mutex);
+}
+EXPORT_SYMBOL_GPL(devlink_reload_disable);
+
 /**
  *     devlink_free - Free devlink instance resources
  *
@@ -8201,7 +8241,7 @@ static void __net_exit devlink_pernet_pre_exit(struct net *net)
                        if (WARN_ON(!devlink_reload_supported(devlink)))
                                continue;
                        err = devlink_reload(devlink, &init_net, NULL);
-                       if (err)
+                       if (err && err != -EOPNOTSUPP)
                                pr_warn("Failed to reload devlink instance into init_net\n");
                }
        }