mirror of
https://github.com/libvirt/libvirt.git
synced 2025-02-25 18:55:26 -06:00
5155ab4b2a
In one of recent commits (v9.0.0-rc1~106) I've made our QEMU
namespace code umount the original /dev. One of the reasons was
enhanced security, because previously we just mounted a tmpfs
over the original /dev. Thus a malicious QEMU could just
umount("/dev") and it would get to the original /dev with all
nodes.
Now, on some systems this introduced a regression:
failed to umount devfs on /dev: Device or resource busy
But how this could be? We've moved all file systems mounted under
/dev to a temporary location. Or have we? As it turns out, not
quite. If there are two file systems mounted on the same target,
e.g. like this:
mount -t tmpfs tmpfs /dev/shm/ && mount -t tmpfs tmpfs /dev/shm/
then only the top most (i.e. the last one) is moved. See
qemuDomainUnshareNamespace() for more info.
Now, we could enhance our code to deal with these "doubled" mount
points. Or, since it is the top most file system that is
accessible anyways (and this one is preserved), we can
umount("/dev") in a recursive fashion.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2167302
Fixes: 379c0ce4bf
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jim Fehlig <jfehlig@suse.com>
libvirt library code README
===========================
The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.
The files directly in this directory are supporting the public API
entry points & data structures.
There are two core shared modules to be aware of:
* util/ - a collection of shared APIs that can be used by any
code. This directory is always in the include path
for all things built
* conf/ - APIs for parsing / manipulating all the official XML
files used by the public API. This directory is only
in the include path for driver implementation modules
* vmx/ - VMware VMX config handling (used by esx/ and vmware/)
Then there are the hypervisor implementations:
* bhyve - bhyve - The BSD Hypervisor
* esx/ - VMware ESX and GSX support using vSphere API over SOAP
* hyperv/ - Microsoft Hyper-V support using WinRM
* lxc/ - Linux Native Containers
* openvz/ - OpenVZ containers using cli tools
* qemu/ - QEMU / KVM using qemu CLI/monitor
* remote/ - Generic libvirt native RPC client
* test/ - A "mock" driver for testing
* vbox/ - Virtual Box using native API
* vmware/ - VMware Workstation and Player using the vmrun tool
* xen/ - Xen using hypercalls, XenD SEXPR & XenStore
Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU and Xen drivers.
The ESX, Hyper-V, Remote, Test & VirtualBox drivers all
implement the secondary drivers directly
* cpu/ - CPU feature management
* interface/ - Host network interface management
* network/ - Virtual NAT networking
* nwfilter/ - Network traffic filtering rules
* node_device/ - Host device enumeration
* secret/ - Secret management
* security/ - Mandatory access control drivers
* storage/ - Storage management drivers
Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories