[libvirt] [PATCHv2 1/3] v1: allow guest to guest IPv6 without gateway definition

This patch adds the capability for virtual guests to do IPv6 communication via a virtual network interface with no IPv6 (gateway) addresses specified. This capability currently exists for IPv4. This patch allows creation of a completely isolated IPv6 network. Note that virtual guests cannot communication with the virtualization host via this interface. Also note that: net.ipv6.conf.<interface_name>.disable_ipv6 = 1 Also not that starting libvirtd has set the following: net.bridge.bridge-nf-call-arptables = 1 net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 although /etc/syslog.conf has them all set to 0. Note: If it is desired to control this behavior by having something like ipv6='yes' on the <network> statement, then this should also be done for ipv4. --- docs/formatnetwork.html.in | 18 ++++++++++++++++++ src/network/bridge_driver.c | 22 ++++++++++++++-------- 2 files changed, 32 insertions(+), 8 deletions(-) diff --git a/docs/formatnetwork.html.in b/docs/formatnetwork.html.in index 49206dd..7b3b25c 100644 --- a/docs/formatnetwork.html.in +++ b/docs/formatnetwork.html.in @@ -773,5 +773,23 @@ &lt;/forward&gt; &lt;/network&gt;</pre> + <h3><a name="examplesNoGateway">Network config with no gateway addresses</a></h3> + + <p> + A valid network definition can contain no IPv4 or IPv6 addresses. Such a definition + can be used for a "very private" or "very isolated" network since it will not be + possible to communicate with the virtualization host via this network. However, + this virtual network interface can be used for communication between virtual guest + systems. This works for IPv4 and <span class="since">(Since 1.0.1)</span> IPv6. + </p> + + <pre> + &lt;network&gt; + &lt;name&gt;nogw&lt;/name&gt; + &lt;uuid&gt;7a3b7497-1ec7-8aef-6d5c-38dff9109e93&lt;/uuid&gt; + &lt;bridge name="virbr2" stp="on" delay="0" /&gt; + &lt;mac address='00:16:3E:5D:C7:9E'/&gt; + &lt;/network&gt;</pre> + </body> </html> diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c index 75f3c3a..0fdb635 100644 --- a/src/network/bridge_driver.c +++ b/src/network/bridge_driver.c @@ -1617,15 +1617,16 @@ networkRemoveRoutingIptablesRules(struct network_driver *driver, } } -/* Add all once/network rules required for IPv6 (if any IPv6 addresses are defined) */ +/* Add all once/network rules required for IPv6. + * Even if no IPv6 addresses are defined, allow IPv6 commuinications + * between virtual systems. If any IPv6 addresses are defined, then + * add the rules for regular operation. + */ static int networkAddGeneralIp6tablesRules(struct network_driver *driver, virNetworkObjPtr network) { - if (!virNetworkDefGetIpByIndex(network->def, AF_INET6, 0)) - return 0; - /* Catch all rules to block forwarding to/from bridges */ if (iptablesAddForwardRejectOut(driver->iptables, AF_INET6, @@ -1653,6 +1654,10 @@ networkAddGeneralIp6tablesRules(struct network_driver *driver, goto err3; } + /* if no IPv6 addresses are defined, we are done. */ + if (!virNetworkDefGetIpByIndex(network->def, AF_INET6, 0)) + return 0; + /* allow DNS over IPv6 */ if (iptablesAddTcpInput(driver->iptables, AF_INET6, network->def->bridge, 53) < 0) { @@ -1689,11 +1694,12 @@ static void networkRemoveGeneralIp6tablesRules(struct network_driver *driver, virNetworkObjPtr network) { - if (!virNetworkDefGetIpByIndex(network->def, AF_INET6, 0)) - return; + if (virNetworkDefGetIpByIndex(network->def, AF_INET6, 0)) { + iptablesRemoveUdpInput(driver->iptables, AF_INET6, network->def->bridge, 53); + iptablesRemoveTcpInput(driver->iptables, AF_INET6, network->def->bridge, 53); + } - iptablesRemoveUdpInput(driver->iptables, AF_INET6, network->def->bridge, 53); - iptablesRemoveTcpInput(driver->iptables, AF_INET6, network->def->bridge, 53); + /* the following rules are there even if no IPv6 address has been defined */ iptablesRemoveForwardAllowCross(driver->iptables, AF_INET6, network->def->bridge); iptablesRemoveForwardRejectIn(driver->iptables, AF_INET6, network->def->bridge); iptablesRemoveForwardRejectOut(driver->iptables, AF_INET6, network->def->bridge); -- 1.7.11.7