mctp: Allow local delivery to the null EID

[ Upstream commit 1f6c77ac9e6ecef152fd5df94c4b3c346adb197a ]

We may need to receive packets addressed to the null EID (==0), but
addressed to us at the physical layer.

This change adds a lookup for local routes when we see a packet
addressed to EID 0, and a local phys address.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 5093bbfc10ab ("mctp: perform route lookups under a RCU read-side lock")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/mctp/route.c b/net/mctp/route.c
index 89e67399249b47206c0235fd8ce35d8e6c9d8f86..859f57fd3871f174533037a0719a2a744f2b2e49 100644 (file)
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -480,6 +480,10 @@ static int mctp_alloc_local_tag(struct mctp_sock *msk,
        int rc = -EAGAIN;
        u8 tagbits;
 
+       /* for NULL destination EIDs, we may get a response from any peer */
+       if (daddr == MCTP_ADDR_NULL)
+               daddr = MCTP_ADDR_ANY;
+
        /* be optimistic, alloc now */
        key = mctp_key_alloc(msk, saddr, daddr, 0, GFP_KERNEL);
        if (!key)
@@ -558,6 +562,20 @@ struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
        return rt;
 }
 
+static struct mctp_route *mctp_route_lookup_null(struct net *net,
+                                                struct net_device *dev)
+{
+       struct mctp_route *rt;
+
+       list_for_each_entry_rcu(rt, &net->mctp.routes, list) {
+               if (rt->dev->dev == dev && rt->type == RTN_LOCAL &&
+                   refcount_inc_not_zero(&rt->refs))
+                       return rt;
+       }
+
+       return NULL;
+}
+
 /* sends a skb to rt and releases the route. */
 int mctp_do_route(struct mctp_route *rt, struct sk_buff *skb)
 {
@@ -853,6 +871,11 @@ static int mctp_pkttype_receive(struct sk_buff *skb, struct net_device *dev,
        rcu_read_unlock();
 
        rt = mctp_route_lookup(net, cb->net, mh->dest);
+
+       /* NULL EID, but addressed to our physical address */
+       if (!rt && mh->dest == MCTP_ADDR_NULL && skb->pkt_type == PACKET_HOST)
+               rt = mctp_route_lookup_null(net, dev);
+
        if (!rt)
                goto err_drop;