[Openstack-security] [Bug 1316271] Re: Network Security: VM hosts can SSH to compute node
David Hill
1316271 at bugs.launchpad.net
Wed May 14 22:37:46 UTC 2014
I'm not quite sure but I doubt this patch will work because we're not
using share_dhcp_address and by default that one is set to false.
Looking at the code, the simplest method to get that enforced is to add
it to iptables.
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https://bugs.launchpad.net/bugs/1316271
Title:
Network Security: VM hosts can SSH to compute node
Status in OpenStack Compute (Nova):
New
Status in OpenStack Security Advisories:
Incomplete
Bug description:
Hi guys,
We're still using nova-network and we'll be using it for a while
and we noticed that the VM guests can contact the compute nodes on all
ports ... The one we're the most preoccupied with is SSH. We've
written the following patch in order to isolate the VM guests from the
VM hosts.
--- linux_net.py.orig 2014-05-05 17:25:10.171746968 +0000
+++ linux_net.py 2014-05-05 18:42:54.569209220 +0000
@@ -805,6 +805,24 @@
@utils.synchronized('lock_gateway', external=True)
+def isolate_compute_from_guest(network_ref):
+ if not network_ref:
+ return
+
+ iptables_manager.ipv4['filter'].add_rule('INPUT',
+ '-p tcp -d %s --dport 8775 '
+ '-j ACCEPT' % network_ref['dhcp_server'])
+ iptables_manager.ipv4['filter'].add_rule('FORWARD',
+ '-p tcp -d %s --dport 8775 '
+ '-j ACCEPT' % network_ref['dhcp_server'])
+ iptables_manager.ipv4['filter'].add_rule('INPUT',
+ '-d %s '
+ '-j DROP' % network_ref['dhcp_server'])
+ iptables_manager.ipv4['filter'].add_rule('FORWARD',
+ '-d %s '
+ '-j DROP' % network_ref['dhcp_server'])
+ iptables_manager.apply()
+
def initialize_gateway_device(dev, network_ref):
if not network_ref:
return
@@ -1046,6 +1064,7 @@
try:
_execute('kill', '-HUP', pid, run_as_root=True)
_add_dnsmasq_accept_rules(dev)
+ isolate_compute_from_guest(network_ref)
return
except Exception as exc: # pylint: disable=W0703
LOG.error(_('Hupping dnsmasq threw %s'), exc)
@@ -1098,6 +1117,7 @@
_add_dnsmasq_accept_rules(dev)
+ isolate_compute_from_guest(network_ref)
@utils.synchronized('radvd_start')
def update_ra(context, dev, network_ref):
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