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 "0000:00:10.0" >/sys/bus/pci/drivers/mlxsw_spectrum2/bind
        devlink dev reload pci/0000:00:10.0 &
        echo "0000:00:10.0" >/sys/bus/pci/drivers/mlxsw_spectrum2/unbind
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>
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 69bb6bb06e769a2b944d523980f31f7a491976e3..d44ac666e730d4760137e8a985117ec36bc1d6ad 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/main.c
@@ -4010,6 +4010,7 @@ 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;
 
@@ -4121,6 +4122,8 @@ 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 4421ab22182fe7c5d254dba03e5b3ab415ea392a..20e9dc46cacd9a044b7083e9a2a7177387625880 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlxsw/core.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core.c
@@ -1186,8 +1186,10 @@ __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;
 
@@ -1249,6 +1251,8 @@ 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 54ca6681ba3182fa758f3eb1a6c768726ec92cb7..44c2d857a7fa2fd3a3228d384023f3fb785ce329 100644 (file)
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -708,6 +708,7 @@ nsim_dev_create(struct nsim_bus_dev *nsim_bus_dev, unsigned int port_count)
                goto err_debugfs_exit;
 
        devlink_params_publish(devlink);
+       devlink_reload_enable(devlink);
        return nsim_dev;
 
 err_debugfs_exit:
@@ -732,6 +733,7 @@ static void nsim_dev_destroy(struct nsim_dev *nsim_dev)
 {
        struct devlink *devlink = priv_to_devlink(nsim_dev);
 
+       devlink_reload_disable(devlink);
        nsim_bpf_dev_exit(nsim_dev);
        nsim_dev_debugfs_exit(nsim_dev);
        nsim_dev_traps_exit(devlink);

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 23e4b65ec9df4b0fb33c00b943d3253bcaeab86c..2116c88663a155634da926b0e2228c887b8a2fa7 100644 (file)
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -38,7 +38,8 @@ struct devlink {
        struct device *dev;
        possible_net_t _net;
        struct mutex lock;
-       bool reload_failed;
+       u8 reload_failed:1,
+          reload_enabled:1;
        char priv[0] __aligned(NETDEV_ALIGN);
 };
 
@@ -774,6 +775,8 @@ struct ib_device;
 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 f80151eeaf51691e762e9a5c46b70f4c258c8c07..7d64660a72fc3487c32f1d13193b152d6998fc59 100644 (file)
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -2699,7 +2699,7 @@ static int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
        struct devlink *devlink = info->user_ptr[0];
        int err;
 
-       if (!devlink_reload_supported(devlink))
+       if (!devlink_reload_supported(devlink) || !devlink->reload_enabled)
                return -EOPNOTSUPP;
 
        err = devlink_resources_validate(devlink, NULL, info);
@@ -6196,12 +6196,49 @@ 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
  *