vxlan: Support MC routing in the underlay

Locally-generated MC packets have so far not been subject to MC routing.
Instead an MC-enabled installation would maintain the MC routing tables,
and separately from that the list of interfaces to send packets to as part
of the VXLAN FDB and MDB.

In a previous patch, a ip_mr_output() and ip6_mr_output() routines were
added for IPv4 and IPv6. All locally generated MC traffic is now passed
through these functions. For reasons of backward compatibility, an SKB
(IPCB / IP6CB) flag guards the actual MC routing.

This patch adds logic to set the flag, and the UAPI to enable the behavior.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/d899655bb7e9b2521ee8c793e67056b9fd02ba12.1750113335.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This commit is contained in:

Petr Machata

2025-06-17 18:18:46 -07:00

committed by

Jakub Kicinski

parent 96e8f5a9fe

commit f8337efa4f

3 changed files with 25 additions and 3 deletions

									
										include/uapi/linux/if_link.h
									
		+1
		
												View File
												
				@@ -1398,6 +1398,7 @@ enum {

					IFLA_VXLAN_LOCALBYPASS,

					IFLA_VXLAN_LABEL_POLICY, /* IPv6 flow label policy; ifla_vxlan_label_policy */

					IFLA_VXLAN_RESERVED_BITS,

					IFLA_VXLAN_MC_ROUTE,

					__IFLA_VXLAN_MAX

				};

				#define IFLA_VXLAN_MAX	(__IFLA_VXLAN_MAX - 1)