On 6/9/20 12:17 PM, Daniel P. Berrangé wrote:
Historically IPv6 did not support NAT, so when IPv6 was added to
libvirt's virtual networks, when requesting <forward mode="nat"/>
libvirt will NOT apply NAT to IPv6 traffic, only IPv4 traffic.
This is an annoying historical design decision as it means we
cannot enable IPv6 automatically. We thus need to introduce a
new attribute
<forward mode="nat">
<nat ipv6="yes"/>
</forward>
The new attribute is a tri-state, so it leaves open the possibility of
us intentionally changing the default behaviour in future to honour
NAT for IPv6.
Any network defined with an older libvirt, and even newly defined
networks that don't have ipv6 set explicitly in the input XML, won't
have an explicit value saved in the config. So if we change the default,
those existing networks will have different behavior. I don't see how we
could change the default without those existing networks getting
automatically changed to ipv6='yes'.
Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
---
docs/formatnetwork.html.in | 14 +++++++++
docs/schemas/network.rng | 5 ++++
src/conf/network_conf.c | 30 +++++++++++++++++--
src/conf/network_conf.h | 2 ++
.../nat-network-forward-nat-ipv6.xml | 10 +++++++
.../nat-network-forward-nat-ipv6.xml | 10 +++++++
tests/networkxml2xmltest.c | 1 +
7 files changed, 69 insertions(+), 3 deletions(-)
create mode 100644 tests/networkxml2xmlin/nat-network-forward-nat-ipv6.xml
create mode 100644 tests/networkxml2xmlout/nat-network-forward-nat-ipv6.xml
diff --git a/docs/formatnetwork.html.in b/docs/formatnetwork.html.in
index 0383e2d891..fb740111b1 100644
--- a/docs/formatnetwork.html.in
+++ b/docs/formatnetwork.html.in
@@ -276,6 +276,20 @@
</nat>
</forward>
...</pre>
+
+ <p>
+ <span class="since">Since 6.5.0</span> it is possible to
+ enable NAT with IPv6 networking. As noted above, IPv6
+ has historically done plain forwarding and thus to avoid
+ breaking historical compatibility, IPv6 NAT must be
+ explicitly requested.
+ </p>
+ <pre>
+...
+ <forward mode='nat'>
+ <nat ipv6='yes'/>
+ </forward>
+...</pre>
</dd>
<dt><code>route</code></dt>
diff --git a/docs/schemas/network.rng b/docs/schemas/network.rng
index 88b6f4dfdd..3a5eb3ced4 100644
--- a/docs/schemas/network.rng
+++ b/docs/schemas/network.rng
@@ -181,6 +181,11 @@
</optional>
<optional>
<element name='nat'>
+ <optional>
+ <attribute name="ipv6">
+ <ref name="virYesNo"/>
+ </attribute>
+ </optional>
<interleave>
<optional>
<element name='address'>
diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
index f1d22b25b1..1b89e2985d 100644
--- a/src/conf/network_conf.c
+++ b/src/conf/network_conf.c
@@ -1358,6 +1358,7 @@ virNetworkForwardNatDefParseXML(const char *networkName,
int nNatAddrs, nNatPorts;
char *addrStart = NULL;
char *addrEnd = NULL;
+ char *ipv6 = NULL;
Eww. I just noticed this file isn't doing autofree memory allocation on
many of its pointers...
VIR_XPATH_NODE_AUTORESTORE(ctxt);
ctxt->node = node;
@@ -1369,6 +1370,20 @@ virNetworkForwardNatDefParseXML(const char *networkName,
goto cleanup;
}
+ ipv6 = virXMLPropString(node, "ipv6");
+ if (ipv6) {
+ int natIPv6;
+ if ((natIPv6 = virTristateBoolTypeFromString(ipv6)) <= 0) {
+ virReportError(VIR_ERR_XML_ERROR,
+ _("Invalid ipv6 setting '%s' "
+ "in network '%s' NAT"),
+ ipv6, networkName);
+ goto cleanup;
...which leads to a memory leak here, since the code at the cleanup
label doesn't free ipv6.
For some reason I felt like spending an hour doing something mindless
just now, so I made a patch to convert all the char* and xmlNodePtr* in
network_conf.c to g_autofree (along with a few other g_autoptr things,
and the standard cleanup/error label removals). I'll post that as a
patch based on your patches; you can either just assume that my patch
will go in after yours and fix the memory leak, or you can just change
ipv6 to a g_autofree yourself and I'll adjust my patch accordingly.
+ }
+ def->natIPv6 = natIPv6;
+ VIR_FREE(ipv6);
+ }
+
/* addresses for SNAT */
nNatAddrs = virXPathNodeSet("./address", ctxt, &natAddrNodes);
if (nNatAddrs < 0) {
@@ -2516,10 +2531,18 @@ virNetworkForwardNatDefFormat(virBufferPtr buf,
goto cleanup;
}
- if (!addrEnd && !addrStart && !fwd->port.start && !fwd->port.end)
+ if (!addrEnd && !addrStart && !fwd->port.start && !fwd->port.end && !fwd->natIPv6)
return 0;
- virBufferAddLit(buf, "<nat>\n");
+ virBufferAddLit(buf, "<nat");
+ if (fwd->natIPv6)
+ virBufferAsprintf(buf, " ipv6='%s'", virTristateBoolTypeToString(fwd->natIPv6));
+
+ if (!addrEnd && !addrStart && !fwd->port.start && !fwd->port.end) {
+ virBufferAddLit(buf, "/>\n");
+ return 0;
+ }
+ virBufferAddLit(buf, ">\n");
virBufferAdjustIndent(buf, 2);
if (addrStart) {
@@ -2627,7 +2650,8 @@ virNetworkDefFormatBuf(virBufferPtr buf,
|| def->forward.port.start
|| def->forward.port.end
|| (def->forward.driverName
- != VIR_NETWORK_FORWARD_DRIVER_NAME_DEFAULT));
+ != VIR_NETWORK_FORWARD_DRIVER_NAME_DEFAULT)
+ || def->forward.natIPv6);
virBufferAsprintf(buf, "%s>\n", shortforward ? "/" : "");
virBufferAdjustIndent(buf, 2);
diff --git a/src/conf/network_conf.h b/src/conf/network_conf.h
index f2dc388ef0..e3a61c62ea 100644
--- a/src/conf/network_conf.h
+++ b/src/conf/network_conf.h
@@ -244,6 +244,8 @@ struct _virNetworkForwardDef {
/* ranges for NAT */
virSocketAddrRange addr;
virPortRange port;
+
+ virTristateBool natIPv6;
};
typedef struct _virPortGroupDef virPortGroupDef;
diff --git a/tests/networkxml2xmlin/nat-network-forward-nat-ipv6.xml b/tests/networkxml2xmlin/nat-network-forward-nat-ipv6.xml
new file mode 100644
index 0000000000..c360941e1e
--- /dev/null
+++ b/tests/networkxml2xmlin/nat-network-forward-nat-ipv6.xml
@@ -0,0 +1,10 @@
+<network>
+ <name>default</name>
+ <uuid>81ff0d90-c91e-6742-64da-4a736edb9a9b</uuid>
+ <bridge name="virbr0"/>
+ <forward mode="nat">
+ <nat ipv6="yes"/>
+ </forward>
+ <ip family="ipv6" address="2001:db8:ac10:fe01::1" prefix="64">
+ </ip>
+</network>
diff --git a/tests/networkxml2xmlout/nat-network-forward-nat-ipv6.xml b/tests/networkxml2xmlout/nat-network-forward-nat-ipv6.xml
new file mode 100644
index 0000000000..cfec391ee2
--- /dev/null
+++ b/tests/networkxml2xmlout/nat-network-forward-nat-ipv6.xml
@@ -0,0 +1,10 @@
+<network>
+ <name>default</name>
+ <uuid>81ff0d90-c91e-6742-64da-4a736edb9a9b</uuid>
+ <forward mode='nat'>
+ <nat ipv6='yes'/>
+ </forward>
+ <bridge name='virbr0' stp='on' delay='0'/>
+ <ip family='ipv6' address='2001:db8:ac10:fe01::1' prefix='64'>
+ </ip>
+</network>
diff --git a/tests/networkxml2xmltest.c b/tests/networkxml2xmltest.c
index 700744785a..17817418b7 100644
--- a/tests/networkxml2xmltest.c
+++ b/tests/networkxml2xmltest.c
@@ -140,6 +140,7 @@ mymain(void)
DO_TEST("nat-network-dns-forward-plain");
DO_TEST("nat-network-dns-forwarders");
DO_TEST("nat-network-dns-forwarder-no-resolv");
+ DO_TEST("nat-network-forward-nat-ipv6");
DO_TEST("nat-network-forward-nat-address");
DO_TEST("nat-network-forward-nat-no-address");
DO_TEST("nat-network-mtu");
I don't know that I agree with the comment about ease of changing the
default in the future (maybe I misunderstood), and if you want the patch
to stand on its own you should fix the one memory leak (my patch will be
posted soon, if not already), but it all looks good and works properly
now (for defining the network at least - I haven't actually tried
getting an IPv6 address on a guest yet, but I'll let you know if there
are any problems :-)
Reviewed-by: Laine Stump <laine@xxxxxxxxxx>
