Re: Use CAP_NET_ADMIN and alias netdev-nlmon instead

On 08/08/2014 11:22 PM, Marcel Holtmann wrote:

Hi,

so I am running this command sequence:

	ip link add name nlmon type nlmon
	ip link set dev nlmon up

With that I get this message in dmesg:

Loading kernel module for a network device with CAP_SYS_MODULE (deprecated).

 > Use CAP_NET_ADMIN and alias netdev-nlmon instead.

The kernel section producing this is dev_load() from net/core/dev_ioctl.c:

         no_module = !dev;
         if (no_module && capable(CAP_NET_ADMIN))
                 no_module = request_module("netdev-%s", name);
         if (no_module && capable(CAP_SYS_MODULE)) {
                 if (!request_module("%s", name))
                         pr_warn("Loading kernel module for a network device with CAP_SYS_MODULE (deprecated).  Use CAP_NET_ADMIN and alias netdev-%s instead.\n",
                                 name);
         }

Since I am explicitly giving the name from userspace, I have no idea why the

 > kernel bugs me in providing netdev-nlmon alias. It makes no sense to me. What
 > is the reasoning behind this?

Could it just be that your process doesn't have CAP_NET_ADMIN set
but CAP_SYS_MODULE instead thus triggering this pr_warn()?

  grep Cap /proc/$$/status ?

Hm, I don't think this is nlmon related, above works fine on my side.