Comment 15 for bug 985184

I think it does interfere with other tennats - Nova applies all IPtables rules in one operation, including those that haven't been changed. The basic approach is:

- Save iptables
- Modify the ones that need changing in this saved file
- Reapply the new settings

If a bug like this causes the reapply to fail part way though it could leave other VMs in other groups on the same host exposed.

Phil

-----Original Message-----
From: <email address hidden> [mailto:<email address hidden>] On Behalf Of Russell Bryant
Sent: 24 April 2012 15:23
To: Day, Phil
Subject: [Bug 985184] Re: Security groups fail to be set correctly if incorrect case is used for protocol specification

I also wonder if we should classify this as 'Medium' or 'Low' instead of 'High' since this can't really be exploited. It doesn't allow any privilege escalation and doesn't interfere with service for other tenants as far as I can tell.

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https://bugs.launchpad.net/bugs/985184

Title:
  Security groups fail to be set correctly if incorrect case is used for
  protocol specification

Status in OpenStack Compute (Nova):
  Triaged

Bug description:
  The high level issue is that if a security group rule is specified
  with the protocol in uppercase (e.g. TCP instead of tcp) on a system
  using the IpTablesFirewallDriver then the security group rules may
  fail to be properly applied, leading to security groups that are more
  open than specified.

  The detail of the issue is as follows (Described from the OSAPI
  perspective, but the problem also exists on EC2)

  When a security group rule is specified with the protocol in upper case it is validated (contrig/security_groups.py: _rule_args_to_dict() regardless of case but stored in the database in the supplied case:
      if ip_protocol.upper() not in ['TCP', 'UDP', 'ICMP']:
                  raise exception.InvalidIpProtocol(protocol=ip_protocol)

    …

    values['protocol'] = ip_protocol

  When the security group refresh is triggered (virt/firewall.py – instance_rules() the protocol check is case sensitive:

                  if protocol in ['udp', 'tcp']:
                      args += self._build_tcp_udp_rule(rule, version)
                  elif protocol == 'icmp':
                      args += self._build_icmp_rule(rule, version)
                  if rule.cidr:
                      LOG.info('Using cidr %r', rule.cidr)
                      args += ['-s', rule.cidr]
                      fw_rules += [' '.join(args)]

  Because the protocol doesn’t match ‘udp’ or ‘tcp’ the protocol part of
  the rule is skipped, leading to an incomplete and invalid iptables
  command line.

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