net: add hwtstamping helpers for stackable net devices

The stackable net devices with hwtstamping support (vlan, macvlan,
bonding) only pass the hwtstamping ops to the lower (real) device.

These drivers are the first that need to be converted to the new
timestamping API, because if they aren't prepared to handle that,
then no real device driver cannot be converted to the new API either.

After studying what vlan_dev_ioctl(), macvlan_eth_ioctl() and
bond_eth_ioctl() have in common, here we propose two generic
implementations of ndo_hwtstamp_get() and ndo_hwtstamp_set() which
can be called by those 3 drivers, with "dev" being their lower device.

These helpers cover both cases, when the lower driver is converted to
the new API or unconverted.

We need some hacks in case of an unconverted driver, namely to stuff
some pointers in struct kernel_hwtstamp_config which shouldn't have
been there (since the new API isn't supposed to need it). These will
be removed when all drivers will have been converted to the new API.

Signed-off-by: Maxim Georgiev <glipus@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20230801142824.1772134-3-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 68 insertions, 7 deletions

diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 10c0e173b38b..d0223ecd6f6f 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -265,14 +265,20 @@ static int dev_get_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 	if (!netif_device_present(dev))
 		return -ENODEV;
 
+	kernel_cfg.ifr = ifr;
 	err = ops->ndo_hwtstamp_get(dev, &kernel_cfg);
 	if (err)
 		return err;
 
-	hwtstamp_config_from_kernel(&cfg, &kernel_cfg);
+	/* If the request was resolved through an unconverted driver, omit
+	 * the copy_to_user(), since the implementation has already done that
+	 */
+	if (!kernel_cfg.copied_to_user) {
+		hwtstamp_config_from_kernel(&cfg, &kernel_cfg);
 
-	if (copy_to_user(ifr->ifr_data, &cfg, sizeof(cfg)))
-		return -EFAULT;
+		if (copy_to_user(ifr->ifr_data, &cfg, sizeof(cfg)))
+			return -EFAULT;
+	}
 
 	return 0;
 }
@@ -280,7 +286,7 @@ static int dev_get_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 static int dev_set_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
-	struct kernel_hwtstamp_config kernel_cfg;
+	struct kernel_hwtstamp_config kernel_cfg = {};
 	struct netlink_ext_ack extack = {};
 	struct hwtstamp_config cfg;
 	int err;
@@ -289,6 +295,7 @@ static int dev_set_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 		return -EFAULT;
 
 	hwtstamp_config_to_kernel(&kernel_cfg, &cfg);
+	kernel_cfg.ifr = ifr;
 
 	err = net_hwtstamp_validate(&kernel_cfg);
 	if (err)
@@ -317,14 +324,68 @@ static int dev_set_hwtstamp(struct net_device *dev, struct ifreq *ifr)
 	/* The driver may have modified the configuration, so copy the
 	 * updated version of it back to user space
 	 */
-	hwtstamp_config_from_kernel(&cfg, &kernel_cfg);
+	if (!kernel_cfg.copied_to_user) {
+		hwtstamp_config_from_kernel(&cfg, &kernel_cfg);
 
-	if (copy_to_user(ifr->ifr_data, &cfg, sizeof(cfg)))
-		return -EFAULT;
+		if (copy_to_user(ifr->ifr_data, &cfg, sizeof(cfg)))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
+static int generic_hwtstamp_ioctl_lower(struct net_device *dev, int cmd,
+					struct kernel_hwtstamp_config *kernel_cfg)
+{
+	struct ifreq ifrr;
+	int err;
+
+	strscpy_pad(ifrr.ifr_name, dev->name, IFNAMSIZ);
+	ifrr.ifr_ifru = kernel_cfg->ifr->ifr_ifru;
+
+	err = dev_eth_ioctl(dev, &ifrr, cmd);
+	if (err)
+		return err;
+
+	kernel_cfg->ifr->ifr_ifru = ifrr.ifr_ifru;
+	kernel_cfg->copied_to_user = true;
 
 	return 0;
 }
 
+int generic_hwtstamp_get_lower(struct net_device *dev,
+			       struct kernel_hwtstamp_config *kernel_cfg)
+{
+	const struct net_device_ops *ops = dev->netdev_ops;
+
+	if (!netif_device_present(dev))
+		return -ENODEV;
+
+	if (ops->ndo_hwtstamp_get)
+		return ops->ndo_hwtstamp_get(dev, kernel_cfg);
+
+	/* Legacy path: unconverted lower driver */
+	return generic_hwtstamp_ioctl_lower(dev, SIOCGHWTSTAMP, kernel_cfg);
+}
+EXPORT_SYMBOL(generic_hwtstamp_get_lower);
+
+int generic_hwtstamp_set_lower(struct net_device *dev,
+			       struct kernel_hwtstamp_config *kernel_cfg,
+			       struct netlink_ext_ack *extack)
+{
+	const struct net_device_ops *ops = dev->netdev_ops;
+
+	if (!netif_device_present(dev))
+		return -ENODEV;
+
+	if (ops->ndo_hwtstamp_set)
+		return ops->ndo_hwtstamp_set(dev, kernel_cfg, extack);
+
+	/* Legacy path: unconverted lower driver */
+	return generic_hwtstamp_ioctl_lower(dev, SIOCSHWTSTAMP, kernel_cfg);
+}
+EXPORT_SYMBOL(generic_hwtstamp_set_lower);
+
 static int dev_siocbond(struct net_device *dev,
 			struct ifreq *ifr, unsigned int cmd)
 {