Kees Cook wrote:
> As part of trying to clean up struct sock_addr, add comments about the
> sockaddr arguments of dev_[gs]et_mac_address() being actual classic "max
> 14 bytes in sa_data" sockaddr instances and not struct sockaddr_storage.
What is this assertion based on?
I see various non-Ethernet .ndo_set_mac_address implementations, which
dev_set_mac_address calls. And dev_set_mac_addr_user is called from
rtnetlink do_setlink. Which kmalloc's sa based on dev->addr_len.
>
> Signed-off-by: Kees Cook <k...@kernel.org>
> ---
> Cc: "David S. Miller" <da...@davemloft.net>
> Cc: Eric Dumazet <eduma...@google.com>
> Cc: Jakub Kicinski <k...@kernel.org>
> Cc: Paolo Abeni <pab...@redhat.com>
> Cc: net...@vger.kernel.org
> ---
> net/core/dev.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 45a8c3dd4a64..5abfd29a35bf 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -9183,7 +9183,8 @@ EXPORT_SYMBOL(dev_pre_changeaddr_notify);
> /**
> * dev_set_mac_address - Change Media Access Control Address
> * @dev: device
> - * @sa: new address
> + * @sa: new address in a classic "struct sockaddr", which will never
> + * have more than 14 bytes in @sa::sa_data
> * @extack: netlink extended ack
> *
> * Change the hardware (MAC) address of the device
> @@ -9217,6 +9218,7 @@ EXPORT_SYMBOL(dev_set_mac_address);
>
> DECLARE_RWSEM(dev_addr_sem);
>
> +/* "sa" is a classic sockaddr: it will only ever use 14 bytes from sa_data.
> */
> int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
> struct netlink_ext_ack *extack)
> {
> @@ -9229,6 +9231,7 @@ int dev_set_mac_address_user(struct net_device *dev,
> struct sockaddr *sa,
> }
> EXPORT_SYMBOL(dev_set_mac_address_user);
>
> +/* "sa" is a classic sockaddr: it will only ever use 14 bytes from sa_data.
> */
> int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)
> {
> size_t size = sizeof(sa->sa_data_min);
> --
> 2.34.1
>
