Public bug reported:
On Ubuntu 10.04 server, after applying the fixes to Libvirt's AppArmor
profiles as discussed in bug 545795 the hot-attachment of USB devices is
blocked/denied by AppArmor. Hot-attachment means: a KVM-based VM is
running and a USB devices connected to the underlying host is to be
attached/passed-through to the VM while it is running. This can be
accomplished by using virt-manager:
1. Open the "Details" window of the virtual machine in question
2. Klick Add Hardware
3. Select "Physical Host Device", Next
4. Select "USB device" and choose the device to be attached (in our case a USB
card reader), Next
5. Finish
The logfile for the machine in question immediately shows:
usb_create: no bus specified, using "usb.0" for "usb-host"
husb: open device 5.2
/dev/bus/usb/005/002: Permission denied
husb: open device 5.2
/dev/bus/usb/005/002: Permission denied
husb: open device 5.2
/dev/bus/usb/005/002: Permission denied
husb: open device 5.2
/var/log/kern.log accordingly shows
kernel: [79029.932635] type=1503 audit(1272985279.341:1009):
operation="open" pid=23782 parent=1 profile="libvirt-959806d1-327a-cd14
-6b3f-ddeee8a19d0e" requested_mask="rw::" denied_mask="rw::" fsuid=0
ouid=0 name="/dev/bus/usb/005/002"
This happens because AppArmor doesn't allow Libvirt access to
/dev/bus/usb/**. Note that this works fine when the machine in question
is shut down prior to attaching the USB device but that is exactly not
the desired behaviour of hot-attaching devices.
This can be fixed quite simply by allowing read-write access to
/dev/bus/usb/**. I don't know if that needs to be added to the profile
abstractions/libvirt-qemu or usr.lib.libvirt.virt-aa-helper. I believe
it is the latter, but I am not sure.
apparmor: 2.5-0ubuntu3
libvirt-bin: 0.7.5-5ubuntu27
Description: Ubuntu 10.04 LTS
Release: 10.04
** Affects: libvirt (Ubuntu)
Importance: Undecided
Status: New
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AppArmor blocks hot-attaching of USB devices
https://bugs.launchpad.net/bugs/578332
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