Merge branch 'net-mctp-add-support-for-gateway-routing'

Jeremy Kerr says:

====================
net: mctp: Add support for gateway routing

This series adds a gateway route type for the MCTP core, allowing
non-local EIDs as the match for a route.

Example setup using the mctp tools:

    mctp route add 9 via mctpi2c0
    mctp neigh add 9 dev mctpi2c0 lladdr 0x1d
    mctp route add 10 gw 9

- will route packets to eid 10 through mctpi2c0, using a dest lladdr
of 0x1d (ie, that of the directly-attached eid 9).

The core change to support this is the introduction of a struct
mctp_dst, which represents the result of a route lookup. Since this
involves a bit of surgery through the routing code, we add a few tests
along the way.

We're introducing an ABI change in the new RTM_{NEW,GET,DEL}ROUTE
netlink formats, with the support for a RTA_GATEWAY attribute. Because
we need a network ID specified to fully-qualify a gateway EID, the
RTA_GATEWAY attribute carries the (net, eid) tuple in full:

    struct mctp_fq_addr {
        unsigned int net;
        mctp_eid_t eid;
    }

Of course, any questions, comments etc are most welcome.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
====================

Link: https://patch.msgid.link/20250702-dev-forwarding-v5-0-1468191da8a4@codeconstruct.com.au
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 194 insertions, 2 deletions

diff --git a/net/mctp/test/utils.c b/net/mctp/test/utils.c
index 565763eb0211..01f5af416b81 100644
--- a/net/mctp/test/utils.c
+++ b/net/mctp/test/utils.c
@@ -26,19 +26,22 @@ static void mctp_test_dev_setup(struct net_device *ndev)
 	ndev->type = ARPHRD_MCTP;
 	ndev->mtu = MCTP_DEV_TEST_MTU;
 	ndev->hard_header_len = 0;
-	ndev->addr_len = 0;
 	ndev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
 	ndev->flags = IFF_NOARP;
 	ndev->netdev_ops = &mctp_test_netdev_ops;
 	ndev->needs_free_netdev = true;
 }
 
-struct mctp_test_dev *mctp_test_create_dev(void)
+static struct mctp_test_dev *__mctp_test_create_dev(unsigned short lladdr_len,
+						    const unsigned char *lladdr)
 {
 	struct mctp_test_dev *dev;
 	struct net_device *ndev;
 	int rc;
 
+	if (WARN_ON(lladdr_len > MAX_ADDR_LEN))
+		return NULL;
+
 	ndev = alloc_netdev(sizeof(*dev), "mctptest%d", NET_NAME_ENUM,
 			    mctp_test_dev_setup);
 	if (!ndev)
@@ -46,6 +49,8 @@ struct mctp_test_dev *mctp_test_create_dev(void)
 
 	dev = netdev_priv(ndev);
 	dev->ndev = ndev;
+	ndev->addr_len = lladdr_len;
+	dev_addr_set(ndev, lladdr);
 
 	rc = register_netdev(ndev);
 	if (rc) {
@@ -61,8 +66,195 @@ struct mctp_test_dev *mctp_test_create_dev(void)
 	return dev;
 }
 
+struct mctp_test_dev *mctp_test_create_dev(void)
+{
+	return __mctp_test_create_dev(0, NULL);
+}
+
+struct mctp_test_dev *mctp_test_create_dev_lladdr(unsigned short lladdr_len,
+						  const unsigned char *lladdr)
+{
+	return __mctp_test_create_dev(lladdr_len, lladdr);
+}
+
 void mctp_test_destroy_dev(struct mctp_test_dev *dev)
 {
 	mctp_dev_put(dev->mdev);
 	unregister_netdev(dev->ndev);
 }
+
+static const unsigned int test_pktqueue_magic = 0x5f713aef;
+
+void mctp_test_pktqueue_init(struct mctp_test_pktqueue *tpq)
+{
+	tpq->magic = test_pktqueue_magic;
+	skb_queue_head_init(&tpq->pkts);
+}
+
+static int mctp_test_dst_output(struct mctp_dst *dst, struct sk_buff *skb)
+{
+	struct kunit *test = current->kunit_test;
+	struct mctp_test_pktqueue *tpq = test->priv;
+
+	KUNIT_ASSERT_EQ(test, tpq->magic, test_pktqueue_magic);
+
+	skb_queue_tail(&tpq->pkts, skb);
+
+	return 0;
+}
+
+/* local version of mctp_route_alloc() */
+static struct mctp_test_route *mctp_route_test_alloc(void)
+{
+	struct mctp_test_route *rt;
+
+	rt = kzalloc(sizeof(*rt), GFP_KERNEL);
+	if (!rt)
+		return NULL;
+
+	INIT_LIST_HEAD(&rt->rt.list);
+	refcount_set(&rt->rt.refs, 1);
+	rt->rt.output = mctp_test_dst_output;
+
+	return rt;
+}
+
+struct mctp_test_route *mctp_test_create_route_direct(struct net *net,
+						      struct mctp_dev *dev,
+						      mctp_eid_t eid,
+						      unsigned int mtu)
+{
+	struct mctp_test_route *rt;
+
+	rt = mctp_route_test_alloc();
+	if (!rt)
+		return NULL;
+
+	rt->rt.min = eid;
+	rt->rt.max = eid;
+	rt->rt.mtu = mtu;
+	rt->rt.type = RTN_UNSPEC;
+	rt->rt.dst_type = MCTP_ROUTE_DIRECT;
+	if (dev)
+		mctp_dev_hold(dev);
+	rt->rt.dev = dev;
+
+	list_add_rcu(&rt->rt.list, &net->mctp.routes);
+
+	return rt;
+}
+
+struct mctp_test_route *mctp_test_create_route_gw(struct net *net,
+						  unsigned int netid,
+						  mctp_eid_t eid,
+						  mctp_eid_t gw,
+						  unsigned int mtu)
+{
+	struct mctp_test_route *rt;
+
+	rt = mctp_route_test_alloc();
+	if (!rt)
+		return NULL;
+
+	rt->rt.min = eid;
+	rt->rt.max = eid;
+	rt->rt.mtu = mtu;
+	rt->rt.type = RTN_UNSPEC;
+	rt->rt.dst_type = MCTP_ROUTE_GATEWAY;
+	rt->rt.gateway.eid = gw;
+	rt->rt.gateway.net = netid;
+
+	list_add_rcu(&rt->rt.list, &net->mctp.routes);
+
+	return rt;
+}
+
+/* Convenience function for our test dst; release with mctp_test_dst_release()
+ */
+void mctp_test_dst_setup(struct kunit *test, struct mctp_dst *dst,
+			 struct mctp_test_dev *dev,
+			 struct mctp_test_pktqueue *tpq, unsigned int mtu)
+{
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, dev);
+
+	memset(dst, 0, sizeof(*dst));
+
+	dst->dev = dev->mdev;
+	__mctp_dev_get(dst->dev->dev);
+	dst->mtu = mtu;
+	dst->output = mctp_test_dst_output;
+	mctp_test_pktqueue_init(tpq);
+	test->priv = tpq;
+}
+
+void mctp_test_dst_release(struct mctp_dst *dst,
+			   struct mctp_test_pktqueue *tpq)
+{
+	mctp_dst_release(dst);
+	skb_queue_purge(&tpq->pkts);
+}
+
+void mctp_test_route_destroy(struct kunit *test, struct mctp_test_route *rt)
+{
+	unsigned int refs;
+
+	rtnl_lock();
+	list_del_rcu(&rt->rt.list);
+	rtnl_unlock();
+
+	if (rt->rt.dst_type == MCTP_ROUTE_DIRECT && rt->rt.dev)
+		mctp_dev_put(rt->rt.dev);
+
+	refs = refcount_read(&rt->rt.refs);
+	KUNIT_ASSERT_EQ_MSG(test, refs, 1, "route ref imbalance");
+
+	kfree_rcu(&rt->rt, rcu);
+}
+
+void mctp_test_skb_set_dev(struct sk_buff *skb, struct mctp_test_dev *dev)
+{
+	struct mctp_skb_cb *cb;
+
+	cb = mctp_cb(skb);
+	cb->net = READ_ONCE(dev->mdev->net);
+	skb->dev = dev->ndev;
+}
+
+struct sk_buff *mctp_test_create_skb(const struct mctp_hdr *hdr,
+				     unsigned int data_len)
+{
+	size_t hdr_len = sizeof(*hdr);
+	struct sk_buff *skb;
+	unsigned int i;
+	u8 *buf;
+
+	skb = alloc_skb(hdr_len + data_len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	__mctp_cb(skb);
+	memcpy(skb_put(skb, hdr_len), hdr, hdr_len);
+
+	buf = skb_put(skb, data_len);
+	for (i = 0; i < data_len; i++)
+		buf[i] = i & 0xff;
+
+	return skb;
+}
+
+struct sk_buff *__mctp_test_create_skb_data(const struct mctp_hdr *hdr,
+					    const void *data, size_t data_len)
+{
+	size_t hdr_len = sizeof(*hdr);
+	struct sk_buff *skb;
+
+	skb = alloc_skb(hdr_len + data_len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	__mctp_cb(skb);
+	memcpy(skb_put(skb, hdr_len), hdr, hdr_len);
+	memcpy(skb_put(skb, data_len), data, data_len);
+
+	return skb;
+}