Commit d07b26f5 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by David S. Miller
Browse files

dev_addr: add a modification check 



netdev->dev_addr should only be modified via helpers,
but someone may be casting off the const. Add a runtime
check to catch abuses.

Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5f0b6923

include/linux/netdevice.h

+5 −0
Original line number Diff line number Diff line
@@ -1942,6 +1942,8 @@ enum netdev_ml_priv_type { 
 *	@unlink_list:	As netif_addr_lock() can be called recursively,

 *			keep a list of interfaces to be deleted.

 *

 *	@dev_addr_shadow:	Copy of @dev_addr to catch direct writes.

 *

 *	FIXME: cleanup struct net_device such that network protocol info

 *	moves out.

 */
@@ -2268,6 +2270,8 @@ struct net_device { 


	/* protected by rtnl_lock */

	struct bpf_xdp_entity	xdp_state[__MAX_XDP_MODE];



	u8 dev_addr_shadow[MAX_ADDR_LEN];

};

#define to_net_dev(d) container_of(d, struct net_device, dev)
@@ -4288,6 +4292,7 @@ int dev_addr_del(struct net_device *dev, const unsigned char *addr, 
		 unsigned char addr_type);

void dev_addr_flush(struct net_device *dev);

int dev_addr_init(struct net_device *dev);

void dev_addr_check(struct net_device *dev);



/* Functions used for unicast addresses handling */

int dev_uc_add(struct net_device *dev, const unsigned char *addr);

net/core/dev.c

+1 −0
Original line number Diff line number Diff line
@@ -1377,6 +1377,7 @@ static int __dev_open(struct net_device *dev, struct netlink_ext_ack *extack) 
	int ret;



	ASSERT_RTNL();

	dev_addr_check(dev);



	if (!netif_device_present(dev)) {

		/* may be detached because parent is runtime-suspended */

net/core/dev_addr_lists.c

+19 −0
Original line number Diff line number Diff line
@@ -498,6 +498,21 @@ EXPORT_SYMBOL(__hw_addr_init); 
 * Device addresses handling functions

 */



/* Check that netdev->dev_addr is not written to directly as this would

 * break the rbtree layout. All changes should go thru dev_addr_set() and co.

 * Remove this check in mid-2024.

 */

void dev_addr_check(struct net_device *dev)

{

	if (!memcmp(dev->dev_addr, dev->dev_addr_shadow, MAX_ADDR_LEN))

		return;



	netdev_warn(dev, "Current addr:  %*ph\n", MAX_ADDR_LEN, dev->dev_addr);

	netdev_warn(dev, "Expected addr: %*ph\n",

		    MAX_ADDR_LEN, dev->dev_addr_shadow);

	netdev_WARN(dev, "Incorrect netdev->dev_addr\n");

}



/**

 *	dev_addr_flush - Flush device address list

 *	@dev: device
@@ -509,6 +524,7 @@ EXPORT_SYMBOL(__hw_addr_init); 
void dev_addr_flush(struct net_device *dev)

{

	/* rtnl_mutex must be held here */

	dev_addr_check(dev);



	__hw_addr_flush(&dev->dev_addrs);

	dev->dev_addr = NULL;
@@ -552,8 +568,11 @@ void dev_addr_mod(struct net_device *dev, unsigned int offset, 
{

	struct netdev_hw_addr *ha;



	dev_addr_check(dev);



	ha = container_of(dev->dev_addr, struct netdev_hw_addr, addr[0]);

	memcpy(&ha->addr[offset], addr, len);

	memcpy(&dev->dev_addr_shadow[offset], addr, len);

}

EXPORT_SYMBOL(dev_addr_mod);