net: core: Convert dev_set_mac_address_user() to use struct sockaddr_storage

Convert callers of dev_set_mac_address_user() to use struct
sockaddr_storage. Add sanity checks on dev->addr_len usage.

Signed-off-by: Kees Cook <kees@kernel.org>
Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://patch.msgid.link/20250521204619.2301870-8-kees@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: kees

drivers/net/tap.c

@@ -923,7 +923,7 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
 	unsigned int __user *up = argp;
 	unsigned short u;
 	int __user *sp = argp;
-	struct sockaddr sa;
+	struct sockaddr_storage ss;
 	int s;
 	int ret;
 
@@ -1000,24 +1000,28 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
 			return -ENOLINK;
 		}
 		ret = 0;
-		dev_get_mac_address(&sa, dev_net(tap->dev), tap->dev->name);
+		dev_get_mac_address((struct sockaddr *)&ss, dev_net(tap->dev),
+				    tap->dev->name);
 		if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
-		    copy_to_user(&ifr->ifr_hwaddr, &sa, sizeof(sa)))
+		    copy_to_user(&ifr->ifr_hwaddr, &ss, sizeof(ifr->ifr_hwaddr)))
 			ret = -EFAULT;
 		tap_put_tap_dev(tap);
 		rtnl_unlock();
 		return ret;
 
 	case SIOCSIFHWADDR:
-		if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa)))
+		if (copy_from_user(&ss, &ifr->ifr_hwaddr, sizeof(ifr->ifr_hwaddr)))
 			return -EFAULT;
 		rtnl_lock();
 		tap = tap_get_tap_dev(q);
 		if (!tap) {
 			rtnl_unlock();
 			return -ENOLINK;
 		}
-		ret = dev_set_mac_address_user(tap->dev, &sa, NULL);
+		if (tap->dev->addr_len > sizeof(ifr->ifr_hwaddr))
+			ret = -EINVAL;
+		else
+			ret = dev_set_mac_address_user(tap->dev, &ss, NULL);
 		tap_put_tap_dev(tap);
 		rtnl_unlock();
 		return ret;

drivers/net/tun.c

@@ -3193,7 +3193,13 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 
 	case SIOCSIFHWADDR:
 		/* Set hw address */
-		ret = dev_set_mac_address_user(tun->dev, &ifr.ifr_hwaddr, NULL);
+		if (tun->dev->addr_len > sizeof(ifr.ifr_hwaddr)) {
+			ret = -EINVAL;
+			break;
+		}
+		ret = dev_set_mac_address_user(tun->dev,
+					       (struct sockaddr_storage *)&ifr.ifr_hwaddr,
+					       NULL);
 		break;
 
 	case TUNGETSNDBUF:

include/linux/netdevice.h

@@ -4216,7 +4216,7 @@ int netif_set_mac_address(struct net_device *dev, struct sockaddr_storage *ss,
 			  struct netlink_ext_ack *extack);
 int dev_set_mac_address(struct net_device *dev, struct sockaddr_storage *ss,
 			struct netlink_ext_ack *extack);
-int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
+int dev_set_mac_address_user(struct net_device *dev, struct sockaddr_storage *ss,
 			     struct netlink_ext_ack *extack);
 int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name);
 int dev_get_port_parent_id(struct net_device *dev,

net/core/dev_api.c

@@ -84,14 +84,15 @@ void dev_set_group(struct net_device *dev, int new_group)
 	netdev_unlock_ops(dev);
 }
 
-int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
+int dev_set_mac_address_user(struct net_device *dev,
+			     struct sockaddr_storage *ss,
 			     struct netlink_ext_ack *extack)
 {
 	int ret;
 
 	down_write(&dev_addr_sem);
 	netdev_lock_ops(dev);
-	ret = netif_set_mac_address(dev, (struct sockaddr_storage *)sa, extack);
+	ret = netif_set_mac_address(dev, ss, extack);
 	netdev_unlock_ops(dev);
 	up_write(&dev_addr_sem);
 

net/core/dev_ioctl.c

@@ -572,9 +572,11 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,
 		return dev_set_mtu(dev, ifr->ifr_mtu);
 
 	case SIOCSIFHWADDR:
-		if (dev->addr_len > sizeof(struct sockaddr))
+		if (dev->addr_len > sizeof(ifr->ifr_hwaddr))
 			return -EINVAL;
-		return dev_set_mac_address_user(dev, &ifr->ifr_hwaddr, NULL);
+		return dev_set_mac_address_user(dev,
+						(struct sockaddr_storage *)&ifr->ifr_hwaddr,
+						NULL);
 
 	case SIOCSIFHWBROADCAST:
 		if (ifr->ifr_hwaddr.sa_family != dev->type)