net: split out SIOCDEVPRIVATE handling from dev_ioctl

SIOCDEVPRIVATE ioctl commands are mainly used in really old
drivers, and they have a number of problems:

- They hide behind the normal .ndo_do_ioctl function that
  is also used for other things in modern drivers, so it's
  hard to spot a driver that actually uses one of these

- Since drivers use a number different calling conventions,
  it is impossible to support compat mode for them in
  a generic way.

- With all drivers using the same 16 commands codes, there
  is no way to introspect the data being passed through
  things like strace.

Add a new net_device_ops callback pointer, to address the
first two of these. Separating them from .ndo_do_ioctl
makes it easy to grep for drivers with a .ndo_siocdevprivate
callback, and the unwieldy name hopefully makes it easier
to spot in code review.

By passing the ifreq structure and the ifr_data pointer
separately, it is no longer necessary to overload these,
and the driver can use either one for a given command.

Cc: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/networking/netdevices.rst b/Documentation/networking/netdevices.rst
index 17bdcb7..02f1faa 100644 (file)
--- a/Documentation/networking/netdevices.rst
+++ b/Documentation/networking/netdevices.rst
@@ -222,6 +222,13 @@ ndo_do_ioctl:
        Synchronization: rtnl_lock() semaphore.
        Context: process
 
+ndo_siocdevprivate:
+       Synchronization: rtnl_lock() semaphore.
+       Context: process
+
+       This is used to implement SIOCDEVPRIVATE ioctl helpers.
+       These should not be added to new drivers, so don't use.
+
 ndo_get_stats:
        Synchronization: rtnl_lock() semaphore, dev_base_lock rwlock, or RCU.
        Context: atomic (can't sleep under rwlock or RCU)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c871dc2..670e1a8 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1361,6 +1361,9 @@ struct net_device_ops {
        int                     (*ndo_validate_addr)(struct net_device *dev);
        int                     (*ndo_do_ioctl)(struct net_device *dev,
                                                struct ifreq *ifr, int cmd);
+       int                     (*ndo_siocdevprivate)(struct net_device *dev,
+                                                     struct ifreq *ifr,
+                                                     void __user *data, int cmd);
        int                     (*ndo_set_config)(struct net_device *dev,
                                                  struct ifmap *map);
        int                     (*ndo_change_mtu)(struct net_device *dev,

diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 950e2fe..75e3e34 100644 (file)
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -259,6 +259,23 @@ static int dev_do_ioctl(struct net_device *dev,
        return err;
 }
 
+static int dev_siocdevprivate(struct net_device *dev,
+                             struct ifreq *ifr, unsigned int cmd)
+{
+       const struct net_device_ops *ops = dev->netdev_ops;
+       void __user *data = ifr->ifr_data;
+
+       if (ops->ndo_siocdevprivate) {
+               if (netif_device_present(dev))
+                       return ops->ndo_siocdevprivate(dev, ifr, data, cmd);
+               else
+                       return -ENODEV;
+       }
+
+       /* fall back to do_ioctl for drivers not yet converted */
+       return dev_do_ioctl(dev, ifr, cmd);
+}
+
 /*
  *     Perform the SIOCxIFxxx calls, inside rtnl_lock()
  */
@@ -336,9 +353,11 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, unsigned int cmd)
         *      Unknown or private ioctl
         */
        default:
-               if ((cmd >= SIOCDEVPRIVATE &&
-                   cmd <= SIOCDEVPRIVATE + 15) ||
-                   cmd == SIOCBONDENSLAVE ||
+               if (cmd >= SIOCDEVPRIVATE &&
+                   cmd <= SIOCDEVPRIVATE + 15)
+                       return dev_siocdevprivate(dev, ifr, cmd);
+
+               if (cmd == SIOCBONDENSLAVE ||
                    cmd == SIOCBONDRELEASE ||
                    cmd == SIOCBONDSETHWADDR ||
                    cmd == SIOCBONDSLAVEINFOQUERY ||