On 02/07/2014 08:33 AM, Daniel P. Berrange wrote:
Rewrite lxcDomainAttachDeviceHostdevStorageLive function to use the virProcessRunInMountNamespace helper. This avoids risk of a malicious guest replacing /dev with a absolute symlink, tricking the driver into changing the host OS filesystem.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com> --- src/lxc/lxc_driver.c | 64 ++++++++++++++-------------------------------------- 1 file changed, 17 insertions(+), 47 deletions(-)
+ if (virCgroupAllowDevicePath(priv->cgroup, + def->source.caps.u.storage.block, + VIR_CGROUP_DEVICE_RWM) != 0) { virReportError(VIR_ERR_INTERNAL_ERROR, _("cannot allow device %s for domain %s"), def->source.caps.u.storage.block, vm->def->name);
Here, I think we're okay setting up cgroup by name - because it is the host-visible name, not the guest-visible name, and cgroup just stat()s the host name to use the major:minor anyways. But since we already have sb.st_rdev, why not avoid a second stat() and just tell cgroup to change by major:minor in the first place?
goto cleanup; }
+ if (lxcDomainAttachDeviceMknod(driver, + 0700 | S_IFBLK, + sb.st_rdev, + vm, + dev, + def->source.caps.u.storage.block) < 0) { + if (virCgroupDenyDevicePath(priv->cgroup, + def->source.caps.u.storage.block, + VIR_CGROUP_DEVICE_RWM) != 0) + VIR_WARN("cannot deny device %s for domain %s", + def->source.caps.u.storage.block, vm->def->name); + goto cleanup;
Same problem as in 10/14 about no audit of cleanup attempts. And again, something probably worth fixing in its own patch, so for this one: ACK. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org