mctp: Add initial routing framework

Add a simple routing table, and a couple of route output handlers, and
the mctp packet_type & handler.

Includes changes from Matt Johnston <matt@codeconstruct.com.au>.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 75 insertions, 0 deletions

diff --git a/include/net/mctp.h b/include/net/mctp.h
index 61452e03aa85..4094bec5e5db 100644
--- a/include/net/mctp.h
+++ b/include/net/mctp.h
@@ -11,6 +11,7 @@
 
 #include <linux/bits.h>
 #include <linux/mctp.h>
+#include <net/net_namespace.h>
 
 /* MCTP packet definitions */
 struct mctp_hdr {
@@ -33,6 +34,8 @@ struct mctp_hdr {
 #define MCTP_HDR_TAG_SHIFT	0
 #define MCTP_HDR_TAG_MASK	GENMASK(2, 0)
 
+#define MCTP_HEADER_MAXLEN	4
+
 static inline bool mctp_address_ok(mctp_eid_t eid)
 {
 	return eid >= 8 && eid < 255;
@@ -43,6 +46,78 @@ static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb)
 	return (struct mctp_hdr *)skb_network_header(skb);
 }
 
+struct mctp_skb_cb {
+	unsigned int	magic;
+	unsigned int	net;
+	mctp_eid_t	src;
+};
+
+/* skb control-block accessors with a little extra debugging for initial
+ * development.
+ *
+ * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb
+ * with mctp_cb().
+ *
+ * __mctp_cb() is only for the initial ingress code; we should see ->magic set
+ * at all times after this.
+ */
+static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb)
+{
+	struct mctp_skb_cb *cb = (void *)skb->cb;
+
+	cb->magic = 0x4d435450;
+	return cb;
+}
+
+static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb)
+{
+	struct mctp_skb_cb *cb = (void *)skb->cb;
+
+	WARN_ON(cb->magic != 0x4d435450);
+	return (void *)(skb->cb);
+}
+
+/* Route definition.
+ *
+ * These are held in the pernet->mctp.routes list, with RCU protection for
+ * removed routes. We hold a reference to the netdev; routes need to be
+ * dropped on NETDEV_UNREGISTER events.
+ *
+ * Updates to the route table are performed under rtnl; all reads under RCU,
+ * so routes cannot be referenced over a RCU grace period. Specifically: A
+ * caller cannot block between mctp_route_lookup and passing the route to
+ * mctp_do_route.
+ */
+struct mctp_route {
+	mctp_eid_t		min, max;
+
+	struct mctp_dev		*dev;
+	unsigned int		mtu;
+	int			(*output)(struct mctp_route *route,
+					  struct sk_buff *skb);
+
+	struct list_head	list;
+	refcount_t		refs;
+	struct rcu_head		rcu;
+};
+
+/* route interfaces */
+struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
+				     mctp_eid_t daddr);
+
+int mctp_do_route(struct mctp_route *rt, struct sk_buff *skb);
+
+int mctp_local_output(struct sock *sk, struct mctp_route *rt,
+		      struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag);
+
+/* routing <--> device interface */
+int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr);
+int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr);
+void mctp_route_remove_dev(struct mctp_dev *mdev);
+
+int mctp_routes_init(void);
+void mctp_routes_exit(void);
+
 void mctp_device_init(void);
 void mctp_device_exit(void);