Incorrect handling of non-existing network devices

[jackburton]

The Network stack handles non-existing network devices incorrectly:

ifconfig /dev/net/foobar auto-config

causes the network stack to allocate resources for the non-existing interface.

The stack or the ethernet module should probably check if a device with the given name exists in allocate_device_interface() or in ethernet_init() respectively. Reproducible under qemu.

[jackburton]

Interestingly, this allows for things like

~/Desktop> ifconfig /dev/net/../zero auto-config
~/Desktop> ifconfig /dev/net/../zero up
ifconfig: Setting flags failed: Operation not allowed

or

~/Desktop> ifconfig /dev/net/../../system auto-config
~/Desktop> ifconfig /dev/net/../../system up
ifconfig: Setting flags failed: Is a directory

But the interface exists, and the net_stack will happily try to assign an address via DHCP.

[jackburton]

Proposed patch

[jackburton]

The attached patch fixes the bug (although not the problem described in comment 1). Is it okay to apply it ? Is there any reason why the ethernet device should be created without the /dev/net/ entry ? I'm not that familiar with our device manager, so...

[jackburton]

Avoid creating interface for paths with ".."

[jackburton]

Fixes also the other problem. Any objection if I apply these patches ?

[axeld]

While in theory you are allowed to name your interface as you wish, since /dev/net/ is handled by the ethernet device driver, your patches definitely make sense, so please go ahead.

[jackburton]

Fixed in hrev46340.