Merge branch 'net-convert-dev_set_mac_address-to-struct-sockaddr_storage'

Kees Cook says:

====================
net: Convert dev_set_mac_address() to struct sockaddr_storage

As part of the effort to allow the compiler to reason about object sizes,
we need to deal with the problematic variably sized struct sockaddr,
which has no internal runtime size tracking. In much of the network
stack the use of struct sockaddr_storage has been adopted. Continue the
transition toward this for more of the internal APIs. Specifically:

- inet_addr_is_any()
- netif_set_mac_address()
- dev_set_mac_address()
- dev_set_mac_address_user()

Only a few callers of dev_set_mac_address() needed adjustment; all others
were already using struct sockaddr_storage internally.

v1: https://lore.kernel.org/all/20250520222452.work.063-kees@kernel.org/
====================

Link: https://patch.msgid.link/20250521204310.it.500-kees@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

5 files changed, 24 insertions, 31 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 3eb4e945f312..2b514d95c528 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9669,7 +9669,7 @@ int dev_pre_changeaddr_notify(struct net_device *dev, const char *addr,
 }
 EXPORT_SYMBOL(dev_pre_changeaddr_notify);
 
-int netif_set_mac_address(struct net_device *dev, struct sockaddr *sa,
+int netif_set_mac_address(struct net_device *dev, struct sockaddr_storage *ss,
 			  struct netlink_ext_ack *extack)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
@@ -9677,15 +9677,15 @@ int netif_set_mac_address(struct net_device *dev, struct sockaddr *sa,
 
 	if (!ops->ndo_set_mac_address)
 		return -EOPNOTSUPP;
-	if (sa->sa_family != dev->type)
+	if (ss->ss_family != dev->type)
 		return -EINVAL;
 	if (!netif_device_present(dev))
 		return -ENODEV;
-	err = dev_pre_changeaddr_notify(dev, sa->sa_data, extack);
+	err = dev_pre_changeaddr_notify(dev, ss->__data, extack);
 	if (err)
 		return err;
-	if (memcmp(dev->dev_addr, sa->sa_data, dev->addr_len)) {
-		err = ops->ndo_set_mac_address(dev, sa);
+	if (memcmp(dev->dev_addr, ss->__data, dev->addr_len)) {
+		err = ops->ndo_set_mac_address(dev, ss);
 		if (err)
 			return err;
 	}
@@ -9697,6 +9697,7 @@ int netif_set_mac_address(struct net_device *dev, struct sockaddr *sa,
 
 DECLARE_RWSEM(dev_addr_sem);
 
+/* "sa" is a true struct sockaddr with limited "sa_data" member. */
 int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)
 {
 	size_t size = sizeof(sa->sa_data_min);
diff --git a/net/core/dev_api.c b/net/core/dev_api.c
index f9a160ab596f..1bf0153195f2 100644
--- a/net/core/dev_api.c
+++ b/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, sa, extack);
+	ret = netif_set_mac_address(dev, ss, extack);
 	netdev_unlock_ops(dev);
 	up_write(&dev_addr_sem);
 
@@ -319,20 +320,20 @@ EXPORT_SYMBOL(dev_set_allmulti);
 /**
  * dev_set_mac_address() - change Media Access Control Address
  * @dev: device
- * @sa: new address
+ * @ss: new address
  * @extack: netlink extended ack
  *
  * Change the hardware (MAC) address of the device
  *
  * Return: 0 on success, -errno on failure.
  */
-int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
+int dev_set_mac_address(struct net_device *dev, struct sockaddr_storage *ss,
 			struct netlink_ext_ack *extack)
 {
 	int ret;
 
 	netdev_lock_ops(dev);
-	ret = netif_set_mac_address(dev, sa, extack);
+	ret = netif_set_mac_address(dev, ss, extack);
 	netdev_unlock_ops(dev);
 
 	return ret;
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index fff13a8b48f1..616479e71466 100644
--- a/net/core/dev_ioctl.c
+++ b/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)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 8a914b37ef6e..f9a35bdc58ad 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3080,17 +3080,7 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev,
 	}
 
 	if (tb[IFLA_ADDRESS]) {
-		struct sockaddr *sa;
-		int len;
-
-		len = sizeof(sa_family_t) + max_t(size_t, dev->addr_len,
-						  sizeof(*sa));
-		sa = kmalloc(len, GFP_KERNEL);
-		if (!sa) {
-			err = -ENOMEM;
-			goto errout;
-		}
-		sa->sa_family = dev->type;
+		struct sockaddr_storage ss = { };
 
 		netdev_unlock_ops(dev);
 
@@ -3098,10 +3088,9 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev,
 		down_write(&dev_addr_sem);
 		netdev_lock_ops(dev);
 
-		memcpy(sa->sa_data, nla_data(tb[IFLA_ADDRESS]),
-		       dev->addr_len);
-		err = netif_set_mac_address(dev, sa, extack);
-		kfree(sa);
+		ss.ss_family = dev->type;
+		memcpy(ss.__data, nla_data(tb[IFLA_ADDRESS]), dev->addr_len);
+		err = netif_set_mac_address(dev, &ss, extack);
 		if (err) {
 			up_write(&dev_addr_sem);
 			goto errout;
diff --git a/net/core/utils.c b/net/core/utils.c
index 27f4cffaae05..e47feeaa5a49 100644
--- a/net/core/utils.c
+++ b/net/core/utils.c
@@ -399,9 +399,9 @@ int inet_pton_with_scope(struct net *net, __kernel_sa_family_t af,
 }
 EXPORT_SYMBOL(inet_pton_with_scope);
 
-bool inet_addr_is_any(struct sockaddr *addr)
+bool inet_addr_is_any(struct sockaddr_storage *addr)
 {
-	if (addr->sa_family == AF_INET6) {
+	if (addr->ss_family == AF_INET6) {
 		struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)addr;
 		const struct sockaddr_in6 in6_any =
 			{ .sin6_addr = IN6ADDR_ANY_INIT };
@@ -409,13 +409,13 @@ bool inet_addr_is_any(struct sockaddr *addr)
 		if (!memcmp(in6->sin6_addr.s6_addr,
 			    in6_any.sin6_addr.s6_addr, 16))
 			return true;
-	} else if (addr->sa_family == AF_INET) {
+	} else if (addr->ss_family == AF_INET) {
 		struct sockaddr_in *in = (struct sockaddr_in *)addr;
 
 		if (in->sin_addr.s_addr == htonl(INADDR_ANY))
 			return true;
 	} else {
-		pr_warn("unexpected address family %u\n", addr->sa_family);
+		pr_warn("unexpected address family %u\n", addr->ss_family);
 	}
 
 	return false;