module loading with CAP_NET_ADMIN

From: Vasiliy Kulikov
Date: Thu Feb 24 2011 - 10:12:54 EST

Hi netdev folks,

I'd like to discuss the ability to load any modules from /lib/modules/
by a process with CAP_NET_ADMIN. Since Linux 2.6.32 [1] there is such

root@albatros:~# grep Cap /proc/$$/status
CapInh: 0000000000000000
CapPrm: fffffffc00001000
CapEff: fffffffc00001000
CapBnd: fffffffc00001000
root@albatros:~# lsmod | grep xfs
root@albatros:~# ifconfig xfs
xfs: error fetching interface information: Device not found
root@albatros:~# lsmod | grep xfs
xfs 767011 0
exportfs 4226 2 xfs,nfsd

Ability of CAP_NET_ADMIN to load the driver to work with a particular
network device is rational; however, one may load any module not even
related to network this way. Hopefully, this is not equal to
CAP_SYS_MODULE since the module set is restricted to /lib/modules
(additionally may be disabled with /proc/sys/kernel/modules_disabled),
but the idea of non-netdev module loading is weird.

My proposal is changing request_module("%s", name) to something like
request_module("netdev-%s", name) inside of dev_load() and adding
aliases to related drivers. This would allow to load only netdev
modules via these ioctls. I'm not sure what modules should be patches -
at least real physical netdevices have names different from drivers'
names, so they don't need patching. I suppose the list is not big.

Any comments are welcome.



Vasiliy Kulikov - bringing security into open computing environments
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at