networkd: introduce vxcan netdev. (#7150)

Similar to the virtual ethernet driver veth, vxcan implements a
local CAN traffic tunnel between two virtual CAN network devices.
When creating a vxcan, two vxcan devices are created as pair
When one end receives the packet it appears on its pair and vice
versa. The vxcan can be used for cross namespace communication.

src/libsystemd/sd-netlink/netlink-types.c

@@ -37,6 +37,10 @@
 #include <linux/if_tunnel.h>
 #include <linux/fib_rules.h>
 
+#if HAVE_VXCAN_INFO_PEER
+#include <linux/can/vxcan.h>
+#endif
+
 #include "macro.h"
 #include "missing.h"
 #include "netlink-types.h"
@@ -92,6 +96,10 @@ static const NLType rtnl_link_info_data_veth_types[] = {
         [VETH_INFO_PEER]  = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_link_type_system, .size = sizeof(struct ifinfomsg) },
 };
 
+static const NLType rtnl_link_info_data_vxcan_types[] = {
+        [VXCAN_INFO_PEER]  = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_link_type_system, .size = sizeof(struct ifinfomsg) },
+};
+
 static const NLType rtnl_link_info_data_ipvlan_types[] = {
         [IFLA_IPVLAN_MODE]  = { .type = NETLINK_TYPE_U16 },
 };
@@ -328,6 +336,8 @@ static const char* const nl_union_link_info_data_table[] = {
         [NL_UNION_LINK_INFO_DATA_VRF] = "vrf",
         [NL_UNION_LINK_INFO_DATA_VCAN] = "vcan",
         [NL_UNION_LINK_INFO_DATA_GENEVE] = "geneve",
+        [NL_UNION_LINK_INFO_DATA_VXCAN] = "vxcan",
+
 };
 
 DEFINE_STRING_TABLE_LOOKUP(nl_union_link_info_data, NLUnionLinkInfoData);
@@ -371,6 +381,8 @@ static const NLTypeSystem rtnl_link_info_data_type_systems[] = {
                                                        .types = rtnl_link_info_data_vrf_types },
         [NL_UNION_LINK_INFO_DATA_GENEVE] =           { .count = ELEMENTSOF(rtnl_link_info_data_geneve_types),
                                                        .types = rtnl_link_info_data_geneve_types },
+        [NL_UNION_LINK_INFO_DATA_VXCAN] =            { .count = ELEMENTSOF(rtnl_link_info_data_vxcan_types),
+                                                       .types = rtnl_link_info_data_vxcan_types },
 };
 
 static const NLTypeSystemUnion rtnl_link_info_data_type_system_union = {

src/libsystemd/sd-netlink/netlink-types.h

@@ -90,6 +90,7 @@ typedef enum NLUnionLinkInfoData {
         NL_UNION_LINK_INFO_DATA_VRF,
         NL_UNION_LINK_INFO_DATA_VCAN,
         NL_UNION_LINK_INFO_DATA_GENEVE,
+        NL_UNION_LINK_INFO_DATA_VXCAN,
         _NL_UNION_LINK_INFO_DATA_MAX,
         _NL_UNION_LINK_INFO_DATA_INVALID = -1
 } NLUnionLinkInfoData;