[Openstack-security] [Bug 1316822] Re: soft reboot of instance does not ensure iptables rules are present

Sean Dague sean at dague.net
Fri Sep 12 01:19:52 UTC 2014


** Changed in: nova
       Status: New => Won't Fix

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https://bugs.launchpad.net/bugs/1316822

Title:
  soft reboot of instance does not ensure iptables rules are present

Status in OpenStack Compute (Nova):
  Won't Fix
Status in OpenStack Security Notes:
  In Progress

Bug description:
  The iptables rules needed to implement instance security group rules
  get inserted by the "_create_domain_and_network" function in
  nova/virt/libvirt/driver.py

  This function is called by the following functions: _hard_reboot,
  resume and spawn (also in a couple of migration related functions).

  Doing "nova reboot <instance_id>" only does a soft reboot
  (_soft_reboot) and assumes that the rules are already present and
  therefore does not check or try to add them.

  If the instances is stopped (nova stop <instance_id>) and nova-compute
  is restarted (for example for a maintenance or problem), the iptables
  rules are removed as observed via output displayed in iptables -S.

  If the instance is started via  nova reboot <instance_id> the rule is
  NOT reapplied until a service nova-compute restart is issued. I have
  reports that this may affect "nova start <instance_id>" as well.

  Depending on if the Cloud is public facing, this opens up a
  potentially huge security vulnerability as an instance can be powered
  on without being protected by any security group rules (not even the
  sg-fallback rule). This is unbeknownst to the instance owner or Cloud
  operators unless they specifically monitor for this situation.

  The code should not do a soft reboot/start and error out or fallback
  to a resume (start)or hard reboot if it detects that the domain is not
  running.

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