Re: [PATCH net] netdev: require admin permission for the bind-tx netlink operation

[Stanislav Fomichev]

On 07/24, Doruk Tan Ozturk wrote:
> The netdev generic-netlink bind-rx operation (NETDEV_CMD_BIND_RX) is
> flagged uns-admin-perm, so binding a dmabuf into a device RX datapath
> requires CAP_NET_ADMIN. The symmetric bind-tx operation
> (NETDEV_CMD_BIND_TX), added later, was given no permission flag. The
> netdev family sets netnsok and has no pre_doit, and
> netdev_nl_bind_tx_doit() performs no capability check, so any
> unprivileged process can bind a dmabuf into a netmem-TX-capable device
> TX datapath.
> 
> net_devmem_bind_dmabuf() attaches and DMA-maps the caller-supplied
> dmabuf to the device and installs TX device-memory state, the same
> class of privileged device operation that bind-rx restricts. Gate
> bind-tx behind uns-admin-perm to match bind-rx.

TX is permission-less by design, it does not modify the netdev in any way.