#include <linux/bits.h>
#include <linux/mctp.h>
+#include <net/net_namespace.h>
/* MCTP packet definitions */
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;
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);
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Management Component Transport Protocol (MCTP) - routing
+ * implementation.
+ *
+ * This is currently based on a simple routing table, with no dst cache. The
+ * number of routes should stay fairly small, so the lookup cost is small.
+ *
+ * Copyright (c) 2021 Code Construct
+ * Copyright (c) 2021 Google
+ */
+
+#include <linux/idr.h>
+#include <linux/mctp.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <linux/skbuff.h>
+
+#include <uapi/linux/if_arp.h>
+
+#include <net/mctp.h>
+#include <net/mctpdevice.h>
+
+/* route output callbacks */
+static int mctp_route_discard(struct mctp_route *route, struct sk_buff *skb)
+{
+ kfree_skb(skb);
+ return 0;
+}
+
+static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
+{
+ /* -> to local stack */
+ /* TODO: socket lookup, reassemble */
+ kfree_skb(skb);
+ return 0;
+}
+
+static int __always_unused mctp_route_output(struct mctp_route *route,
+ struct sk_buff *skb)
+{
+ unsigned int mtu;
+ int rc;
+
+ skb->protocol = htons(ETH_P_MCTP);
+
+ mtu = READ_ONCE(skb->dev->mtu);
+ if (skb->len > mtu) {
+ kfree_skb(skb);
+ return -EMSGSIZE;
+ }
+
+ /* TODO: daddr (from rt->neigh), saddr (from device?) */
+ rc = dev_hard_header(skb, skb->dev, ntohs(skb->protocol),
+ NULL, NULL, skb->len);
+ if (rc) {
+ kfree_skb(skb);
+ return -EHOSTUNREACH;
+ }
+
+ rc = dev_queue_xmit(skb);
+ if (rc)
+ rc = net_xmit_errno(rc);
+
+ return rc;
+}
+
+/* route alloc/release */
+static void mctp_route_release(struct mctp_route *rt)
+{
+ if (refcount_dec_and_test(&rt->refs)) {
+ dev_put(rt->dev->dev);
+ kfree_rcu(rt, rcu);
+ }
+}
+
+/* returns a route with the refcount at 1 */
+static struct mctp_route *mctp_route_alloc(void)
+{
+ struct mctp_route *rt;
+
+ rt = kzalloc(sizeof(*rt), GFP_KERNEL);
+ if (!rt)
+ return NULL;
+
+ INIT_LIST_HEAD(&rt->list);
+ refcount_set(&rt->refs, 1);
+ rt->output = mctp_route_discard;
+
+ return rt;
+}
+
+/* routing lookups */
+static bool mctp_rt_match_eid(struct mctp_route *rt,
+ unsigned int net, mctp_eid_t eid)
+{
+ return READ_ONCE(rt->dev->net) == net &&
+ rt->min <= eid && rt->max >= eid;
+}
+
+/* compares match, used for duplicate prevention */
+static bool mctp_rt_compare_exact(struct mctp_route *rt1,
+ struct mctp_route *rt2)
+{
+ ASSERT_RTNL();
+ return rt1->dev->net == rt2->dev->net &&
+ rt1->min == rt2->min &&
+ rt1->max == rt2->max;
+}
+
+struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
+ mctp_eid_t daddr)
+{
+ struct mctp_route *tmp, *rt = NULL;
+
+ list_for_each_entry_rcu(tmp, &net->mctp.routes, list) {
+ /* TODO: add metrics */
+ if (mctp_rt_match_eid(tmp, dnet, daddr)) {
+ if (refcount_inc_not_zero(&tmp->refs)) {
+ rt = tmp;
+ break;
+ }
+ }
+ }
+
+ return rt;
+}
+
+/* sends a skb to rt and releases the route. */
+int mctp_do_route(struct mctp_route *rt, struct sk_buff *skb)
+{
+ int rc;
+
+ rc = rt->output(rt, skb);
+ mctp_route_release(rt);
+ return rc;
+}
+
+int mctp_local_output(struct sock *sk, struct mctp_route *rt,
+ struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag)
+{
+ struct mctp_skb_cb *cb = mctp_cb(skb);
+ struct mctp_hdr *hdr;
+ unsigned long flags;
+ mctp_eid_t saddr;
+ int rc;
+
+ if (WARN_ON(!rt->dev))
+ return -EINVAL;
+
+ spin_lock_irqsave(&rt->dev->addrs_lock, flags);
+ if (rt->dev->num_addrs == 0) {
+ rc = -EHOSTUNREACH;
+ } else {
+ /* use the outbound interface's first address as our source */
+ saddr = rt->dev->addrs[0];
+ rc = 0;
+ }
+ spin_unlock_irqrestore(&rt->dev->addrs_lock, flags);
+
+ if (rc)
+ return rc;
+
+ /* TODO: we have the route MTU here; packetise */
+
+ skb_reset_transport_header(skb);
+ skb_push(skb, sizeof(struct mctp_hdr));
+ skb_reset_network_header(skb);
+ hdr = mctp_hdr(skb);
+ hdr->ver = 1;
+ hdr->dest = daddr;
+ hdr->src = saddr;
+ hdr->flags_seq_tag = MCTP_HDR_FLAG_SOM | MCTP_HDR_FLAG_EOM; /* TODO */
+
+ skb->protocol = htons(ETH_P_MCTP);
+ skb->priority = 0;
+
+ /* cb->net will have been set on initial ingress */
+ cb->src = saddr;
+
+ return mctp_do_route(rt, skb);
+}
+
+/* route management */
+int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr)
+{
+ struct net *net = dev_net(mdev->dev);
+ struct mctp_route *rt, *ert;
+
+ rt = mctp_route_alloc();
+ if (!rt)
+ return -ENOMEM;
+
+ rt->min = addr;
+ rt->max = addr;
+ rt->dev = mdev;
+ dev_hold(rt->dev->dev);
+ rt->output = mctp_route_input;
+
+ ASSERT_RTNL();
+ /* Prevent duplicate identical routes. */
+ list_for_each_entry(ert, &net->mctp.routes, list) {
+ if (mctp_rt_compare_exact(rt, ert)) {
+ mctp_route_release(rt);
+ return -EEXIST;
+ }
+ }
+
+ list_add_rcu(&rt->list, &net->mctp.routes);
+
+ return 0;
+}
+
+int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr)
+{
+ struct net *net = dev_net(mdev->dev);
+ struct mctp_route *rt, *tmp;
+
+ ASSERT_RTNL();
+
+ list_for_each_entry_safe(rt, tmp, &net->mctp.routes, list) {
+ if (rt->dev == mdev && rt->min == addr && rt->max == addr) {
+ list_del_rcu(&rt->list);
+ /* TODO: immediate RTM_DELROUTE */
+ mctp_route_release(rt);
+ }
+ }
+
+ return 0;
+}
+
+/* removes all entries for a given device */
+void mctp_route_remove_dev(struct mctp_dev *mdev)
+{
+ struct net *net = dev_net(mdev->dev);
+ struct mctp_route *rt, *tmp;
+
+ ASSERT_RTNL();
+ list_for_each_entry_safe(rt, tmp, &net->mctp.routes, list) {
+ if (rt->dev == mdev) {
+ list_del_rcu(&rt->list);
+ /* TODO: immediate RTM_DELROUTE */
+ mctp_route_release(rt);
+ }
+ }
+}
+
+/* Incoming packet-handling */
+
+static int mctp_pkttype_receive(struct sk_buff *skb, struct net_device *dev,
+ struct packet_type *pt,
+ struct net_device *orig_dev)
+{
+ struct net *net = dev_net(dev);
+ struct mctp_skb_cb *cb;
+ struct mctp_route *rt;
+ struct mctp_hdr *mh;
+
+ /* basic non-data sanity checks */
+ if (dev->type != ARPHRD_MCTP)
+ goto err_drop;
+
+ if (!pskb_may_pull(skb, sizeof(struct mctp_hdr)))
+ goto err_drop;
+
+ skb_reset_transport_header(skb);
+ skb_reset_network_header(skb);
+
+ /* We have enough for a header; decode and route */
+ mh = mctp_hdr(skb);
+ if (mh->ver < MCTP_VER_MIN || mh->ver > MCTP_VER_MAX)
+ goto err_drop;
+
+ cb = __mctp_cb(skb);
+ rcu_read_lock();
+ cb->net = READ_ONCE(__mctp_dev_get(dev)->net);
+ rcu_read_unlock();
+
+ rt = mctp_route_lookup(net, cb->net, mh->dest);
+ if (!rt)
+ goto err_drop;
+
+ mctp_do_route(rt, skb);
+
+ return NET_RX_SUCCESS;
+
+err_drop:
+ kfree_skb(skb);
+ return NET_RX_DROP;
+}
+
+static struct packet_type mctp_packet_type = {
+ .type = cpu_to_be16(ETH_P_MCTP),
+ .func = mctp_pkttype_receive,
+};
+
+/* net namespace implementation */
+static int __net_init mctp_routes_net_init(struct net *net)
+{
+ struct netns_mctp *ns = &net->mctp;
+
+ INIT_LIST_HEAD(&ns->routes);
+ return 0;
+}
+
+static void __net_exit mctp_routes_net_exit(struct net *net)
+{
+ struct mctp_route *rt;
+
+ list_for_each_entry_rcu(rt, &net->mctp.routes, list)
+ mctp_route_release(rt);
+}
+
+static struct pernet_operations mctp_net_ops = {
+ .init = mctp_routes_net_init,
+ .exit = mctp_routes_net_exit,
+};
+
+int __init mctp_routes_init(void)
+{
+ dev_add_pack(&mctp_packet_type);
+ return register_pernet_subsys(&mctp_net_ops);
+}
+
+void __exit mctp_routes_exit(void)
+{
+ unregister_pernet_subsys(&mctp_net_ops);
+ dev_remove_pack(&mctp_packet_type);
+}
projects / platform / kernel / linux-rpi.git / commitdiff