ipv4: ipmr: support multiple tables

This patch adds support for multiple independant multicast routing instances,
named "tables".

Userspace multicast routing daemons can bind to a specific table instance by
issuing a setsockopt call using a new option MRT_TABLE. The table number is
stored in the raw socket data and affects all following ipmr setsockopt(),
getsockopt() and ioctl() calls. By default, a single table (RT_TABLE_DEFAULT)
is created with a default routing rule pointing to it. Newly created pimreg
devices have the table number appended ("pimregX"), with the exception of
devices created in the default table, which are named just "pimreg" for
compatibility reasons.

Packets are directed to a specific table instance using routing rules,
similar to how regular routing rules work. Currently iif, oif and mark
are supported as keys, source and destination addresses could be supported
additionally.

Example usage:

- bind pimd/xorp/... to a specific table:

uint32_t table = 123;
setsockopt(fd, IPPROTO_IP, MRT_TABLE, &table, sizeof(table));

- create routing rules directing packets to the new table:

# ip mrule add iif eth0 lookup 123
# ip mrule add oif eth0 lookup 123

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/mroute.h b/include/linux/mroute.h
index 7ff6c77d6008..fa04b246c9ae 100644
--- a/include/linux/mroute.h
+++ b/include/linux/mroute.h
@@ -27,7 +27,8 @@
 #define MRT_DEL_MFC	(MRT_BASE+5)	/* Delete a multicast forwarding entry	*/
 #define MRT_VERSION	(MRT_BASE+6)	/* Get the kernel multicast version	*/
 #define MRT_ASSERT	(MRT_BASE+7)	/* Activate PIM assert mode		*/
-#define MRT_PIM		(MRT_BASE+8)	/* enable PIM code	*/
+#define MRT_PIM		(MRT_BASE+8)	/* enable PIM code			*/
+#define MRT_TABLE	(MRT_BASE+9)	/* Specify mroute table ID		*/
 
 #define SIOCGETVIFCNT	SIOCPROTOPRIVATE	/* IP protocol privates */
 #define SIOCGETSGCNT	(SIOCPROTOPRIVATE+1)