module loading with CAP_NET_ADMIN
[Posted March 2, 2011 by jake]
| From: |
| Vasiliy Kulikov <segoon-AT-openwall.com> |
| To: |
| netdev-AT-vger.kernel.org |
| Subject: |
| module loading with CAP_NET_ADMIN |
| Date: |
| Thu, 24 Feb 2011 18:12:38 +0300 |
| Message-ID: |
| <20110224151238.GA16916@albatros> |
| Cc: |
| linux-kernel-AT-vger.kernel.org, Kees Cook <kees.cook-AT-canonical.com>,
Eugene Teo <eugene-AT-redhat.com>,
Dan Rosenberg <dan.j.rosenberg-AT-gmail.com>,
"David S. Miller" <davem-AT-davemloft.net> |
| Archive‑link: | |
Article |
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
possibility:
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.
[1]
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-...
Thanks,
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
