net: ipmr: add getlink support

Currently there's no way to dump the VIF table for an ipmr table other
than the default (via proc). This is a major issue when debugging ipmr
issues and in general it is good to know which interfaces are
configured. This patch adds support for RTM_GETLINK for the ipmr family
so we can dump the VIF table and the ipmr table's current config for
each table. We're protected by rtnl so no need to acquire RCU or
mrt_lock.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/mroute.h

@@ -110,6 +110,48 @@ struct igmpmsg {
 	struct in_addr im_src,im_dst;
 };
 
+/* ipmr netlink table attributes */
+enum {
+	IPMRA_TABLE_UNSPEC,
+	IPMRA_TABLE_ID,
+	IPMRA_TABLE_CACHE_RES_QUEUE_LEN,
+	IPMRA_TABLE_MROUTE_REG_VIF_NUM,
+	IPMRA_TABLE_MROUTE_DO_ASSERT,
+	IPMRA_TABLE_MROUTE_DO_PIM,
+	IPMRA_TABLE_VIFS,
+	__IPMRA_TABLE_MAX
+};
+#define IPMRA_TABLE_MAX (__IPMRA_TABLE_MAX - 1)
+
+/* ipmr netlink vif attribute format
+ * [ IPMRA_TABLE_VIFS ] - nested attribute
+ *   [ IPMRA_VIF ] - nested attribute
+ *     [ IPMRA_VIFA_xxx ]
+ */
+enum {
+	IPMRA_VIF_UNSPEC,
+	IPMRA_VIF,
+	__IPMRA_VIF_MAX
+};
+#define IPMRA_VIF_MAX (__IPMRA_VIF_MAX - 1)
+
+/* vif-specific attributes */
+enum {
+	IPMRA_VIFA_UNSPEC,
+	IPMRA_VIFA_IFINDEX,
+	IPMRA_VIFA_VIF_ID,
+	IPMRA_VIFA_FLAGS,
+	IPMRA_VIFA_BYTES_IN,
+	IPMRA_VIFA_BYTES_OUT,
+	IPMRA_VIFA_PACKETS_IN,
+	IPMRA_VIFA_PACKETS_OUT,
+	IPMRA_VIFA_LOCAL_ADDR,
+	IPMRA_VIFA_REMOTE_ADDR,
+	IPMRA_VIFA_PAD,
+	__IPMRA_VIFA_MAX
+};
+#define IPMRA_VIFA_MAX (__IPMRA_VIFA_MAX - 1)
+
 /* That's all usermode folks */
 
 #define MFC_ASSERT_THRESH (3*HZ)		/* Maximal freq. of asserts */