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dev_addr: add a modification check

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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: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski 2021-11-19 06:21:53 -08:00 committed by David S. Miller
parent 5f0b692384
commit d07b26f5bb
3 changed files with 25 additions and 0 deletions
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5
include/linux/netdevice.h
View File

@ -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);

1
net/core/dev.c
View File

@ -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 */

19
net/core/dev_addr_lists.c
View File

@ -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);