[PATCH net-next v3 01/31] net: split out SIOCDEVPRIVATE handling from dev_ioctl

Arnd Bergmann
2021-07-27T13:46:05Z

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>
---
Documentation/networking/netdevices.rst | 7 +++++++
include/linux/netdevice.h | 3 +++
net/core/dev_ioctl.c | 25 ++++++++++++++++++++++---
3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/Documentation/networking/netdevices.rst b/Documentation/networking/netdevices.rst
index 17bdcb746dcf..02f1faac839a 100644
--- 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 c871dc223dfa..670e1a8e5928 100644
--- 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 950e2fe5d56a..75e3e340d884 100644
--- 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 ||
--
2.29.2