Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1429 insertions, 0 deletions

diff --git a/net/mctp/route.c b/net/mctp/route.c
new file mode 100644
index 0000000000..7a47a58aa5
--- /dev/null
+++ b/net/mctp/route.c
@@ -0,0 +1,1429 @@
+// 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/kconfig.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>
+#include <net/netlink.h>
+#include <net/sock.h>
+
+#include <trace/events/mctp.h>
+
+static const unsigned int mctp_message_maxlen = 64 * 1024;
+static const unsigned long mctp_key_lifetime = 6 * CONFIG_HZ;
+
+static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev);
+
+/* route output callbacks */
+static int mctp_route_discard(struct mctp_route *route, struct sk_buff *skb)
+{
+	kfree_skb(skb);
+	return 0;
+}
+
+static struct mctp_sock *mctp_lookup_bind(struct net *net, struct sk_buff *skb)
+{
+	struct mctp_skb_cb *cb = mctp_cb(skb);
+	struct mctp_hdr *mh;
+	struct sock *sk;
+	u8 type;
+
+	WARN_ON(!rcu_read_lock_held());
+
+	/* TODO: look up in skb->cb? */
+	mh = mctp_hdr(skb);
+
+	if (!skb_headlen(skb))
+		return NULL;
+
+	type = (*(u8 *)skb->data) & 0x7f;
+
+	sk_for_each_rcu(sk, &net->mctp.binds) {
+		struct mctp_sock *msk = container_of(sk, struct mctp_sock, sk);
+
+		if (msk->bind_net != MCTP_NET_ANY && msk->bind_net != cb->net)
+			continue;
+
+		if (msk->bind_type != type)
+			continue;
+
+		if (!mctp_address_matches(msk->bind_addr, mh->dest))
+			continue;
+
+		return msk;
+	}
+
+	return NULL;
+}
+
+static bool mctp_key_match(struct mctp_sk_key *key, mctp_eid_t local,
+			   mctp_eid_t peer, u8 tag)
+{
+	if (!mctp_address_matches(key->local_addr, local))
+		return false;
+
+	if (key->peer_addr != peer)
+		return false;
+
+	if (key->tag != tag)
+		return false;
+
+	return true;
+}
+
+/* returns a key (with key->lock held, and refcounted), or NULL if no such
+ * key exists.
+ */
+static struct mctp_sk_key *mctp_lookup_key(struct net *net, struct sk_buff *skb,
+					   mctp_eid_t peer,
+					   unsigned long *irqflags)
+	__acquires(&key->lock)
+{
+	struct mctp_sk_key *key, *ret;
+	unsigned long flags;
+	struct mctp_hdr *mh;
+	u8 tag;
+
+	mh = mctp_hdr(skb);
+	tag = mh->flags_seq_tag & (MCTP_HDR_TAG_MASK | MCTP_HDR_FLAG_TO);
+
+	ret = NULL;
+	spin_lock_irqsave(&net->mctp.keys_lock, flags);
+
+	hlist_for_each_entry(key, &net->mctp.keys, hlist) {
+		if (!mctp_key_match(key, mh->dest, peer, tag))
+			continue;
+
+		spin_lock(&key->lock);
+		if (key->valid) {
+			refcount_inc(&key->refs);
+			ret = key;
+			break;
+		}
+		spin_unlock(&key->lock);
+	}
+
+	if (ret) {
+		spin_unlock(&net->mctp.keys_lock);
+		*irqflags = flags;
+	} else {
+		spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
+	}
+
+	return ret;
+}
+
+static struct mctp_sk_key *mctp_key_alloc(struct mctp_sock *msk,
+					  mctp_eid_t local, mctp_eid_t peer,
+					  u8 tag, gfp_t gfp)
+{
+	struct mctp_sk_key *key;
+
+	key = kzalloc(sizeof(*key), gfp);
+	if (!key)
+		return NULL;
+
+	key->peer_addr = peer;
+	key->local_addr = local;
+	key->tag = tag;
+	key->sk = &msk->sk;
+	key->valid = true;
+	spin_lock_init(&key->lock);
+	refcount_set(&key->refs, 1);
+	sock_hold(key->sk);
+
+	return key;
+}
+
+void mctp_key_unref(struct mctp_sk_key *key)
+{
+	unsigned long flags;
+
+	if (!refcount_dec_and_test(&key->refs))
+		return;
+
+	/* even though no refs exist here, the lock allows us to stay
+	 * consistent with the locking requirement of mctp_dev_release_key
+	 */
+	spin_lock_irqsave(&key->lock, flags);
+	mctp_dev_release_key(key->dev, key);
+	spin_unlock_irqrestore(&key->lock, flags);
+
+	sock_put(key->sk);
+	kfree(key);
+}
+
+static int mctp_key_add(struct mctp_sk_key *key, struct mctp_sock *msk)
+{
+	struct net *net = sock_net(&msk->sk);
+	struct mctp_sk_key *tmp;
+	unsigned long flags;
+	int rc = 0;
+
+	spin_lock_irqsave(&net->mctp.keys_lock, flags);
+
+	if (sock_flag(&msk->sk, SOCK_DEAD)) {
+		rc = -EINVAL;
+		goto out_unlock;
+	}
+
+	hlist_for_each_entry(tmp, &net->mctp.keys, hlist) {
+		if (mctp_key_match(tmp, key->local_addr, key->peer_addr,
+				   key->tag)) {
+			spin_lock(&tmp->lock);
+			if (tmp->valid)
+				rc = -EEXIST;
+			spin_unlock(&tmp->lock);
+			if (rc)
+				break;
+		}
+	}
+
+	if (!rc) {
+		refcount_inc(&key->refs);
+		key->expiry = jiffies + mctp_key_lifetime;
+		timer_reduce(&msk->key_expiry, key->expiry);
+
+		hlist_add_head(&key->hlist, &net->mctp.keys);
+		hlist_add_head(&key->sklist, &msk->keys);
+	}
+
+out_unlock:
+	spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
+
+	return rc;
+}
+
+/* Helper for mctp_route_input().
+ * We're done with the key; unlock and unref the key.
+ * For the usual case of automatic expiry we remove the key from lists.
+ * In the case that manual allocation is set on a key we release the lock
+ * and local ref, reset reassembly, but don't remove from lists.
+ */
+static void __mctp_key_done_in(struct mctp_sk_key *key, struct net *net,
+			       unsigned long flags, unsigned long reason)
+__releases(&key->lock)
+{
+	struct sk_buff *skb;
+
+	trace_mctp_key_release(key, reason);
+	skb = key->reasm_head;
+	key->reasm_head = NULL;
+
+	if (!key->manual_alloc) {
+		key->reasm_dead = true;
+		key->valid = false;
+		mctp_dev_release_key(key->dev, key);
+	}
+	spin_unlock_irqrestore(&key->lock, flags);
+
+	if (!key->manual_alloc) {
+		spin_lock_irqsave(&net->mctp.keys_lock, flags);
+		if (!hlist_unhashed(&key->hlist)) {
+			hlist_del_init(&key->hlist);
+			hlist_del_init(&key->sklist);
+			mctp_key_unref(key);
+		}
+		spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
+	}
+
+	/* and one for the local reference */
+	mctp_key_unref(key);
+
+	kfree_skb(skb);
+}
+
+#ifdef CONFIG_MCTP_FLOWS
+static void mctp_skb_set_flow(struct sk_buff *skb, struct mctp_sk_key *key)
+{
+	struct mctp_flow *flow;
+
+	flow = skb_ext_add(skb, SKB_EXT_MCTP);
+	if (!flow)
+		return;
+
+	refcount_inc(&key->refs);
+	flow->key = key;
+}
+
+static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev)
+{
+	struct mctp_sk_key *key;
+	struct mctp_flow *flow;
+
+	flow = skb_ext_find(skb, SKB_EXT_MCTP);
+	if (!flow)
+		return;
+
+	key = flow->key;
+
+	if (WARN_ON(key->dev && key->dev != dev))
+		return;
+
+	mctp_dev_set_key(dev, key);
+}
+#else
+static void mctp_skb_set_flow(struct sk_buff *skb, struct mctp_sk_key *key) {}
+static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev) {}
+#endif
+
+static int mctp_frag_queue(struct mctp_sk_key *key, struct sk_buff *skb)
+{
+	struct mctp_hdr *hdr = mctp_hdr(skb);
+	u8 exp_seq, this_seq;
+
+	this_seq = (hdr->flags_seq_tag >> MCTP_HDR_SEQ_SHIFT)
+		& MCTP_HDR_SEQ_MASK;
+
+	if (!key->reasm_head) {
+		key->reasm_head = skb;
+		key->reasm_tailp = &(skb_shinfo(skb)->frag_list);
+		key->last_seq = this_seq;
+		return 0;
+	}
+
+	exp_seq = (key->last_seq + 1) & MCTP_HDR_SEQ_MASK;
+
+	if (this_seq != exp_seq)
+		return -EINVAL;
+
+	if (key->reasm_head->len + skb->len > mctp_message_maxlen)
+		return -EINVAL;
+
+	skb->next = NULL;
+	skb->sk = NULL;
+	*key->reasm_tailp = skb;
+	key->reasm_tailp = &skb->next;
+
+	key->last_seq = this_seq;
+
+	key->reasm_head->data_len += skb->len;
+	key->reasm_head->len += skb->len;
+	key->reasm_head->truesize += skb->truesize;
+
+	return 0;
+}
+
+static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
+{
+	struct mctp_sk_key *key, *any_key = NULL;
+	struct net *net = dev_net(skb->dev);
+	struct mctp_sock *msk;
+	struct mctp_hdr *mh;
+	unsigned long f;
+	u8 tag, flags;
+	int rc;
+
+	msk = NULL;
+	rc = -EINVAL;
+
+	/* we may be receiving a locally-routed packet; drop source sk
+	 * accounting
+	 */
+	skb_orphan(skb);
+
+	/* ensure we have enough data for a header and a type */
+	if (skb->len < sizeof(struct mctp_hdr) + 1)
+		goto out;
+
+	/* grab header, advance data ptr */
+	mh = mctp_hdr(skb);
+	skb_pull(skb, sizeof(struct mctp_hdr));
+
+	if (mh->ver != 1)
+		goto out;
+
+	flags = mh->flags_seq_tag & (MCTP_HDR_FLAG_SOM | MCTP_HDR_FLAG_EOM);
+	tag = mh->flags_seq_tag & (MCTP_HDR_TAG_MASK | MCTP_HDR_FLAG_TO);
+
+	rcu_read_lock();
+
+	/* lookup socket / reasm context, exactly matching (src,dest,tag).
+	 * we hold a ref on the key, and key->lock held.
+	 */
+	key = mctp_lookup_key(net, skb, mh->src, &f);
+
+	if (flags & MCTP_HDR_FLAG_SOM) {
+		if (key) {
+			msk = container_of(key->sk, struct mctp_sock, sk);
+		} else {
+			/* first response to a broadcast? do a more general
+			 * key lookup to find the socket, but don't use this
+			 * key for reassembly - we'll create a more specific
+			 * one for future packets if required (ie, !EOM).
+			 */
+			any_key = mctp_lookup_key(net, skb, MCTP_ADDR_ANY, &f);
+			if (any_key) {
+				msk = container_of(any_key->sk,
+						   struct mctp_sock, sk);
+				spin_unlock_irqrestore(&any_key->lock, f);
+			}
+		}
+
+		if (!key && !msk && (tag & MCTP_HDR_FLAG_TO))
+			msk = mctp_lookup_bind(net, skb);
+
+		if (!msk) {
+			rc = -ENOENT;
+			goto out_unlock;
+		}
+
+		/* single-packet message? deliver to socket, clean up any
+		 * pending key.
+		 */
+		if (flags & MCTP_HDR_FLAG_EOM) {
+			sock_queue_rcv_skb(&msk->sk, skb);
+			if (key) {
+				/* we've hit a pending reassembly; not much we
+				 * can do but drop it
+				 */
+				__mctp_key_done_in(key, net, f,
+						   MCTP_TRACE_KEY_REPLIED);
+				key = NULL;
+			}
+			rc = 0;
+			goto out_unlock;
+		}
+
+		/* broadcast response or a bind() - create a key for further
+		 * packets for this message
+		 */
+		if (!key) {
+			key = mctp_key_alloc(msk, mh->dest, mh->src,
+					     tag, GFP_ATOMIC);
+			if (!key) {
+				rc = -ENOMEM;
+				goto out_unlock;
+			}
+
+			/* we can queue without the key lock here, as the
+			 * key isn't observable yet
+			 */
+			mctp_frag_queue(key, skb);
+
+			/* if the key_add fails, we've raced with another
+			 * SOM packet with the same src, dest and tag. There's
+			 * no way to distinguish future packets, so all we
+			 * can do is drop; we'll free the skb on exit from
+			 * this function.
+			 */
+			rc = mctp_key_add(key, msk);
+			if (!rc)
+				trace_mctp_key_acquire(key);
+
+			/* we don't need to release key->lock on exit, so
+			 * clean up here and suppress the unlock via
+			 * setting to NULL
+			 */
+			mctp_key_unref(key);
+			key = NULL;
+
+		} else {
+			if (key->reasm_head || key->reasm_dead) {
+				/* duplicate start? drop everything */
+				__mctp_key_done_in(key, net, f,
+						   MCTP_TRACE_KEY_INVALIDATED);
+				rc = -EEXIST;
+				key = NULL;
+			} else {
+				rc = mctp_frag_queue(key, skb);
+			}
+		}
+
+	} else if (key) {
+		/* this packet continues a previous message; reassemble
+		 * using the message-specific key
+		 */
+
+		/* we need to be continuing an existing reassembly... */
+		if (!key->reasm_head)
+			rc = -EINVAL;
+		else
+			rc = mctp_frag_queue(key, skb);
+
+		/* end of message? deliver to socket, and we're done with
+		 * the reassembly/response key
+		 */
+		if (!rc && flags & MCTP_HDR_FLAG_EOM) {
+			sock_queue_rcv_skb(key->sk, key->reasm_head);
+			key->reasm_head = NULL;
+			__mctp_key_done_in(key, net, f, MCTP_TRACE_KEY_REPLIED);
+			key = NULL;
+		}
+
+	} else {
+		/* not a start, no matching key */
+		rc = -ENOENT;
+	}
+
+out_unlock:
+	rcu_read_unlock();
+	if (key) {
+		spin_unlock_irqrestore(&key->lock, f);
+		mctp_key_unref(key);
+	}
+	if (any_key)
+		mctp_key_unref(any_key);
+out:
+	if (rc)
+		kfree_skb(skb);
+	return rc;
+}
+
+static unsigned int mctp_route_mtu(struct mctp_route *rt)
+{
+	return rt->mtu ?: READ_ONCE(rt->dev->dev->mtu);
+}
+
+static int mctp_route_output(struct mctp_route *route, struct sk_buff *skb)
+{
+	struct mctp_skb_cb *cb = mctp_cb(skb);
+	struct mctp_hdr *hdr = mctp_hdr(skb);
+	char daddr_buf[MAX_ADDR_LEN];
+	char *daddr = NULL;
+	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;
+	}
+
+	if (cb->ifindex) {
+		/* direct route; use the hwaddr we stashed in sendmsg */
+		if (cb->halen != skb->dev->addr_len) {
+			/* sanity check, sendmsg should have already caught this */
+			kfree_skb(skb);
+			return -EMSGSIZE;
+		}
+		daddr = cb->haddr;
+	} else {
+		/* If lookup fails let the device handle daddr==NULL */
+		if (mctp_neigh_lookup(route->dev, hdr->dest, daddr_buf) == 0)
+			daddr = daddr_buf;
+	}
+
+	rc = dev_hard_header(skb, skb->dev, ntohs(skb->protocol),
+			     daddr, skb->dev->dev_addr, skb->len);
+	if (rc < 0) {
+		kfree_skb(skb);
+		return -EHOSTUNREACH;
+	}
+
+	mctp_flow_prepare_output(skb, route->dev);
+
+	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)) {
+		mctp_dev_put(rt->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;
+}
+
+unsigned int mctp_default_net(struct net *net)
+{
+	return READ_ONCE(net->mctp.default_net);
+}
+
+int mctp_default_net_set(struct net *net, unsigned int index)
+{
+	if (index == 0)
+		return -EINVAL;
+	WRITE_ONCE(net->mctp.default_net, index);
+	return 0;
+}
+
+/* tag management */
+static void mctp_reserve_tag(struct net *net, struct mctp_sk_key *key,
+			     struct mctp_sock *msk)
+{
+	struct netns_mctp *mns = &net->mctp;
+
+	lockdep_assert_held(&mns->keys_lock);
+
+	key->expiry = jiffies + mctp_key_lifetime;
+	timer_reduce(&msk->key_expiry, key->expiry);
+
+	/* we hold the net->key_lock here, allowing updates to both
+	 * then net and sk
+	 */
+	hlist_add_head_rcu(&key->hlist, &mns->keys);
+	hlist_add_head_rcu(&key->sklist, &msk->keys);
+	refcount_inc(&key->refs);
+}
+
+/* Allocate a locally-owned tag value for (saddr, daddr), and reserve
+ * it for the socket msk
+ */
+struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
+					 mctp_eid_t daddr, mctp_eid_t saddr,
+					 bool manual, u8 *tagp)
+{
+	struct net *net = sock_net(&msk->sk);
+	struct netns_mctp *mns = &net->mctp;
+	struct mctp_sk_key *key, *tmp;
+	unsigned long flags;
+	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)
+		return ERR_PTR(-ENOMEM);
+
+	/* 8 possible tag values */
+	tagbits = 0xff;
+
+	spin_lock_irqsave(&mns->keys_lock, flags);
+
+	/* Walk through the existing keys, looking for potential conflicting
+	 * tags. If we find a conflict, clear that bit from tagbits
+	 */
+	hlist_for_each_entry(tmp, &mns->keys, hlist) {
+		/* We can check the lookup fields (*_addr, tag) without the
+		 * lock held, they don't change over the lifetime of the key.
+		 */
+
+		/* if we don't own the tag, it can't conflict */
+		if (tmp->tag & MCTP_HDR_FLAG_TO)
+			continue;
+
+		if (!(mctp_address_matches(tmp->peer_addr, daddr) &&
+		      mctp_address_matches(tmp->local_addr, saddr)))
+			continue;
+
+		spin_lock(&tmp->lock);
+		/* key must still be valid. If we find a match, clear the
+		 * potential tag value
+		 */
+		if (tmp->valid)
+			tagbits &= ~(1 << tmp->tag);
+		spin_unlock(&tmp->lock);
+
+		if (!tagbits)
+			break;
+	}
+
+	if (tagbits) {
+		key->tag = __ffs(tagbits);
+		mctp_reserve_tag(net, key, msk);
+		trace_mctp_key_acquire(key);
+
+		key->manual_alloc = manual;
+		*tagp = key->tag;
+	}
+
+	spin_unlock_irqrestore(&mns->keys_lock, flags);
+
+	if (!tagbits) {
+		kfree(key);
+		return ERR_PTR(-EBUSY);
+	}
+
+	return key;
+}
+
+static struct mctp_sk_key *mctp_lookup_prealloc_tag(struct mctp_sock *msk,
+						    mctp_eid_t daddr,
+						    u8 req_tag, u8 *tagp)
+{
+	struct net *net = sock_net(&msk->sk);
+	struct netns_mctp *mns = &net->mctp;
+	struct mctp_sk_key *key, *tmp;
+	unsigned long flags;
+
+	req_tag &= ~(MCTP_TAG_PREALLOC | MCTP_TAG_OWNER);
+	key = NULL;
+
+	spin_lock_irqsave(&mns->keys_lock, flags);
+
+	hlist_for_each_entry(tmp, &mns->keys, hlist) {
+		if (tmp->tag != req_tag)
+			continue;
+
+		if (!mctp_address_matches(tmp->peer_addr, daddr))
+			continue;
+
+		if (!tmp->manual_alloc)
+			continue;
+
+		spin_lock(&tmp->lock);
+		if (tmp->valid) {
+			key = tmp;
+			refcount_inc(&key->refs);
+			spin_unlock(&tmp->lock);
+			break;
+		}
+		spin_unlock(&tmp->lock);
+	}
+	spin_unlock_irqrestore(&mns->keys_lock, flags);
+
+	if (!key)
+		return ERR_PTR(-ENOENT);
+
+	if (tagp)
+		*tagp = key->tag;
+
+	return key;
+}
+
+/* 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;
+
+	rcu_read_lock();
+
+	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;
+			}
+		}
+	}
+
+	rcu_read_unlock();
+
+	return rt;
+}
+
+static struct mctp_route *mctp_route_lookup_null(struct net *net,
+						 struct net_device *dev)
+{
+	struct mctp_route *tmp, *rt = NULL;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(tmp, &net->mctp.routes, list) {
+		if (tmp->dev->dev == dev && tmp->type == RTN_LOCAL &&
+		    refcount_inc_not_zero(&tmp->refs)) {
+			rt = tmp;
+			break;
+		}
+	}
+
+	rcu_read_unlock();
+
+	return rt;
+}
+
+static int mctp_do_fragment_route(struct mctp_route *rt, struct sk_buff *skb,
+				  unsigned int mtu, u8 tag)
+{
+	const unsigned int hlen = sizeof(struct mctp_hdr);
+	struct mctp_hdr *hdr, *hdr2;
+	unsigned int pos, size, headroom;
+	struct sk_buff *skb2;
+	int rc;
+	u8 seq;
+
+	hdr = mctp_hdr(skb);
+	seq = 0;
+	rc = 0;
+
+	if (mtu < hlen + 1) {
+		kfree_skb(skb);
+		return -EMSGSIZE;
+	}
+
+	/* keep same headroom as the original skb */
+	headroom = skb_headroom(skb);
+
+	/* we've got the header */
+	skb_pull(skb, hlen);
+
+	for (pos = 0; pos < skb->len;) {
+		/* size of message payload */
+		size = min(mtu - hlen, skb->len - pos);
+
+		skb2 = alloc_skb(headroom + hlen + size, GFP_KERNEL);
+		if (!skb2) {
+			rc = -ENOMEM;
+			break;
+		}
+
+		/* generic skb copy */
+		skb2->protocol = skb->protocol;
+		skb2->priority = skb->priority;
+		skb2->dev = skb->dev;
+		memcpy(skb2->cb, skb->cb, sizeof(skb2->cb));
+
+		if (skb->sk)
+			skb_set_owner_w(skb2, skb->sk);
+
+		/* establish packet */
+		skb_reserve(skb2, headroom);
+		skb_reset_network_header(skb2);
+		skb_put(skb2, hlen + size);
+		skb2->transport_header = skb2->network_header + hlen;
+
+		/* copy header fields, calculate SOM/EOM flags & seq */
+		hdr2 = mctp_hdr(skb2);
+		hdr2->ver = hdr->ver;
+		hdr2->dest = hdr->dest;
+		hdr2->src = hdr->src;
+		hdr2->flags_seq_tag = tag &
+			(MCTP_HDR_TAG_MASK | MCTP_HDR_FLAG_TO);
+
+		if (pos == 0)
+			hdr2->flags_seq_tag |= MCTP_HDR_FLAG_SOM;
+
+		if (pos + size == skb->len)
+			hdr2->flags_seq_tag |= MCTP_HDR_FLAG_EOM;
+
+		hdr2->flags_seq_tag |= seq << MCTP_HDR_SEQ_SHIFT;
+
+		/* copy message payload */
+		skb_copy_bits(skb, pos, skb_transport_header(skb2), size);
+
+		/* do route */
+		rc = rt->output(rt, skb2);
+		if (rc)
+			break;
+
+		seq = (seq + 1) & MCTP_HDR_SEQ_MASK;
+		pos += size;
+	}
+
+	consume_skb(skb);
+	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_sock *msk = container_of(sk, struct mctp_sock, sk);
+	struct mctp_skb_cb *cb = mctp_cb(skb);
+	struct mctp_route tmp_rt = {0};
+	struct mctp_sk_key *key;
+	struct mctp_hdr *hdr;
+	unsigned long flags;
+	unsigned int mtu;
+	mctp_eid_t saddr;
+	bool ext_rt;
+	int rc;
+	u8 tag;
+
+	rc = -ENODEV;
+
+	if (rt) {
+		ext_rt = false;
+		if (WARN_ON(!rt->dev))
+			goto out_release;
+
+	} else if (cb->ifindex) {
+		struct net_device *dev;
+
+		ext_rt = true;
+		rt = &tmp_rt;
+
+		rcu_read_lock();
+		dev = dev_get_by_index_rcu(sock_net(sk), cb->ifindex);
+		if (!dev) {
+			rcu_read_unlock();
+			return rc;
+		}
+		rt->dev = __mctp_dev_get(dev);
+		rcu_read_unlock();
+
+		if (!rt->dev)
+			goto out_release;
+
+		/* establish temporary route - we set up enough to keep
+		 * mctp_route_output happy
+		 */
+		rt->output = mctp_route_output;
+		rt->mtu = 0;
+
+	} else {
+		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)
+		goto out_release;
+
+	if (req_tag & MCTP_TAG_OWNER) {
+		if (req_tag & MCTP_TAG_PREALLOC)
+			key = mctp_lookup_prealloc_tag(msk, daddr,
+						       req_tag, &tag);
+		else
+			key = mctp_alloc_local_tag(msk, daddr, saddr,
+						   false, &tag);
+
+		if (IS_ERR(key)) {
+			rc = PTR_ERR(key);
+			goto out_release;
+		}
+		mctp_skb_set_flow(skb, key);
+		/* done with the key in this scope */
+		mctp_key_unref(key);
+		tag |= MCTP_HDR_FLAG_TO;
+	} else {
+		key = NULL;
+		tag = req_tag & MCTP_TAG_MASK;
+	}
+
+	skb->protocol = htons(ETH_P_MCTP);
+	skb->priority = 0;
+	skb_reset_transport_header(skb);
+	skb_push(skb, sizeof(struct mctp_hdr));
+	skb_reset_network_header(skb);
+	skb->dev = rt->dev->dev;
+
+	/* cb->net will have been set on initial ingress */
+	cb->src = saddr;
+
+	/* set up common header fields */
+	hdr = mctp_hdr(skb);
+	hdr->ver = 1;
+	hdr->dest = daddr;
+	hdr->src = saddr;
+
+	mtu = mctp_route_mtu(rt);
+
+	if (skb->len + sizeof(struct mctp_hdr) <= mtu) {
+		hdr->flags_seq_tag = MCTP_HDR_FLAG_SOM |
+			MCTP_HDR_FLAG_EOM | tag;
+		rc = rt->output(rt, skb);
+	} else {
+		rc = mctp_do_fragment_route(rt, skb, mtu, tag);
+	}
+
+out_release:
+	if (!ext_rt)
+		mctp_route_release(rt);
+
+	mctp_dev_put(tmp_rt.dev);
+
+	return rc;
+}
+
+/* route management */
+static int mctp_route_add(struct mctp_dev *mdev, mctp_eid_t daddr_start,
+			  unsigned int daddr_extent, unsigned int mtu,
+			  unsigned char type)
+{
+	int (*rtfn)(struct mctp_route *rt, struct sk_buff *skb);
+	struct net *net = dev_net(mdev->dev);
+	struct mctp_route *rt, *ert;
+
+	if (!mctp_address_unicast(daddr_start))
+		return -EINVAL;
+
+	if (daddr_extent > 0xff || daddr_start + daddr_extent >= 255)
+		return -EINVAL;
+
+	switch (type) {
+	case RTN_LOCAL:
+		rtfn = mctp_route_input;
+		break;
+	case RTN_UNICAST:
+		rtfn = mctp_route_output;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	rt = mctp_route_alloc();
+	if (!rt)
+		return -ENOMEM;
+
+	rt->min = daddr_start;
+	rt->max = daddr_start + daddr_extent;
+	rt->mtu = mtu;
+	rt->dev = mdev;
+	mctp_dev_hold(rt->dev);
+	rt->type = type;
+	rt->output = rtfn;
+
+	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;
+}
+
+static int mctp_route_remove(struct mctp_dev *mdev, mctp_eid_t daddr_start,
+			     unsigned int daddr_extent, unsigned char type)
+{
+	struct net *net = dev_net(mdev->dev);
+	struct mctp_route *rt, *tmp;
+	mctp_eid_t daddr_end;
+	bool dropped;
+
+	if (daddr_extent > 0xff || daddr_start + daddr_extent >= 255)
+		return -EINVAL;
+
+	daddr_end = daddr_start + daddr_extent;
+	dropped = false;
+
+	ASSERT_RTNL();
+
+	list_for_each_entry_safe(rt, tmp, &net->mctp.routes, list) {
+		if (rt->dev == mdev &&
+		    rt->min == daddr_start && rt->max == daddr_end &&
+		    rt->type == type) {
+			list_del_rcu(&rt->list);
+			/* TODO: immediate RTM_DELROUTE */
+			mctp_route_release(rt);
+			dropped = true;
+		}
+	}
+
+	return dropped ? 0 : -ENOENT;
+}
+
+int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr)
+{
+	return mctp_route_add(mdev, addr, 0, 0, RTN_LOCAL);
+}
+
+int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr)
+{
+	return mctp_route_remove(mdev, addr, 0, RTN_LOCAL);
+}
+
+/* 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_dev *mdev;
+	struct mctp_skb_cb *cb;
+	struct mctp_route *rt;
+	struct mctp_hdr *mh;
+
+	rcu_read_lock();
+	mdev = __mctp_dev_get(dev);
+	rcu_read_unlock();
+	if (!mdev) {
+		/* basic non-data sanity checks */
+		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;
+
+	/* source must be valid unicast or null; drop reserved ranges and
+	 * broadcast
+	 */
+	if (!(mctp_address_unicast(mh->src) || mctp_address_null(mh->src)))
+		goto err_drop;
+
+	/* dest address: as above, but allow broadcast */
+	if (!(mctp_address_unicast(mh->dest) || mctp_address_null(mh->dest) ||
+	      mctp_address_broadcast(mh->dest)))
+		goto err_drop;
+
+	/* MCTP drivers must populate halen/haddr */
+	if (dev->type == ARPHRD_MCTP) {
+		cb = mctp_cb(skb);
+	} else {
+		cb = __mctp_cb(skb);
+		cb->halen = 0;
+	}
+	cb->net = READ_ONCE(mdev->net);
+	cb->ifindex = dev->ifindex;
+
+	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;
+
+	rt->output(rt, skb);
+	mctp_route_release(rt);
+	mctp_dev_put(mdev);
+
+	return NET_RX_SUCCESS;
+
+err_drop:
+	kfree_skb(skb);
+	mctp_dev_put(mdev);
+	return NET_RX_DROP;
+}
+
+static struct packet_type mctp_packet_type = {
+	.type = cpu_to_be16(ETH_P_MCTP),
+	.func = mctp_pkttype_receive,
+};
+
+/* netlink interface */
+
+static const struct nla_policy rta_mctp_policy[RTA_MAX + 1] = {
+	[RTA_DST]		= { .type = NLA_U8 },
+	[RTA_METRICS]		= { .type = NLA_NESTED },
+	[RTA_OIF]		= { .type = NLA_U32 },
+};
+
+/* Common part for RTM_NEWROUTE and RTM_DELROUTE parsing.
+ * tb must hold RTA_MAX+1 elements.
+ */
+static int mctp_route_nlparse(struct sk_buff *skb, struct nlmsghdr *nlh,
+			      struct netlink_ext_ack *extack,
+			      struct nlattr **tb, struct rtmsg **rtm,
+			      struct mctp_dev **mdev, mctp_eid_t *daddr_start)
+{
+	struct net *net = sock_net(skb->sk);
+	struct net_device *dev;
+	unsigned int ifindex;
+	int rc;
+
+	rc = nlmsg_parse(nlh, sizeof(struct rtmsg), tb, RTA_MAX,
+			 rta_mctp_policy, extack);
+	if (rc < 0) {
+		NL_SET_ERR_MSG(extack, "incorrect format");
+		return rc;
+	}
+
+	if (!tb[RTA_DST]) {
+		NL_SET_ERR_MSG(extack, "dst EID missing");
+		return -EINVAL;
+	}
+	*daddr_start = nla_get_u8(tb[RTA_DST]);
+
+	if (!tb[RTA_OIF]) {
+		NL_SET_ERR_MSG(extack, "ifindex missing");
+		return -EINVAL;
+	}
+	ifindex = nla_get_u32(tb[RTA_OIF]);
+
+	*rtm = nlmsg_data(nlh);
+	if ((*rtm)->rtm_family != AF_MCTP) {
+		NL_SET_ERR_MSG(extack, "route family must be AF_MCTP");
+		return -EINVAL;
+	}
+
+	dev = __dev_get_by_index(net, ifindex);
+	if (!dev) {
+		NL_SET_ERR_MSG(extack, "bad ifindex");
+		return -ENODEV;
+	}
+	*mdev = mctp_dev_get_rtnl(dev);
+	if (!*mdev)
+		return -ENODEV;
+
+	if (dev->flags & IFF_LOOPBACK) {
+		NL_SET_ERR_MSG(extack, "no routes to loopback");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct nla_policy rta_metrics_policy[RTAX_MAX + 1] = {
+	[RTAX_MTU]		= { .type = NLA_U32 },
+};
+
+static int mctp_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
+			 struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[RTA_MAX + 1];
+	struct nlattr *tbx[RTAX_MAX + 1];
+	mctp_eid_t daddr_start;
+	struct mctp_dev *mdev;
+	struct rtmsg *rtm;
+	unsigned int mtu;
+	int rc;
+
+	rc = mctp_route_nlparse(skb, nlh, extack, tb,
+				&rtm, &mdev, &daddr_start);
+	if (rc < 0)
+		return rc;
+
+	if (rtm->rtm_type != RTN_UNICAST) {
+		NL_SET_ERR_MSG(extack, "rtm_type must be RTN_UNICAST");
+		return -EINVAL;
+	}
+
+	mtu = 0;
+	if (tb[RTA_METRICS]) {
+		rc = nla_parse_nested(tbx, RTAX_MAX, tb[RTA_METRICS],
+				      rta_metrics_policy, NULL);
+		if (rc < 0)
+			return rc;
+		if (tbx[RTAX_MTU])
+			mtu = nla_get_u32(tbx[RTAX_MTU]);
+	}
+
+	rc = mctp_route_add(mdev, daddr_start, rtm->rtm_dst_len, mtu,
+			    rtm->rtm_type);
+	return rc;
+}
+
+static int mctp_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
+			 struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[RTA_MAX + 1];
+	mctp_eid_t daddr_start;
+	struct mctp_dev *mdev;
+	struct rtmsg *rtm;
+	int rc;
+
+	rc = mctp_route_nlparse(skb, nlh, extack, tb,
+				&rtm, &mdev, &daddr_start);
+	if (rc < 0)
+		return rc;
+
+	/* we only have unicast routes */
+	if (rtm->rtm_type != RTN_UNICAST)
+		return -EINVAL;
+
+	rc = mctp_route_remove(mdev, daddr_start, rtm->rtm_dst_len, RTN_UNICAST);
+	return rc;
+}
+
+static int mctp_fill_rtinfo(struct sk_buff *skb, struct mctp_route *rt,
+			    u32 portid, u32 seq, int event, unsigned int flags)
+{
+	struct nlmsghdr *nlh;
+	struct rtmsg *hdr;
+	void *metrics;
+
+	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*hdr), flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	hdr = nlmsg_data(nlh);
+	hdr->rtm_family = AF_MCTP;
+
+	/* we use the _len fields as a number of EIDs, rather than
+	 * a number of bits in the address
+	 */
+	hdr->rtm_dst_len = rt->max - rt->min;
+	hdr->rtm_src_len = 0;
+	hdr->rtm_tos = 0;
+	hdr->rtm_table = RT_TABLE_DEFAULT;
+	hdr->rtm_protocol = RTPROT_STATIC; /* everything is user-defined */
+	hdr->rtm_scope = RT_SCOPE_LINK; /* TODO: scope in mctp_route? */
+	hdr->rtm_type = rt->type;
+
+	if (nla_put_u8(skb, RTA_DST, rt->min))
+		goto cancel;
+
+	metrics = nla_nest_start_noflag(skb, RTA_METRICS);
+	if (!metrics)
+		goto cancel;
+
+	if (rt->mtu) {
+		if (nla_put_u32(skb, RTAX_MTU, rt->mtu))
+			goto cancel;
+	}
+
+	nla_nest_end(skb, metrics);
+
+	if (rt->dev) {
+		if (nla_put_u32(skb, RTA_OIF, rt->dev->dev->ifindex))
+			goto cancel;
+	}
+
+	/* TODO: conditional neighbour physaddr? */
+
+	nlmsg_end(skb, nlh);
+
+	return 0;
+
+cancel:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+static int mctp_dump_rtinfo(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct net *net = sock_net(skb->sk);
+	struct mctp_route *rt;
+	int s_idx, idx;
+
+	/* TODO: allow filtering on route data, possibly under
+	 * cb->strict_check
+	 */
+
+	/* TODO: change to struct overlay */
+	s_idx = cb->args[0];
+	idx = 0;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(rt, &net->mctp.routes, list) {
+		if (idx++ < s_idx)
+			continue;
+		if (mctp_fill_rtinfo(skb, rt,
+				     NETLINK_CB(cb->skb).portid,
+				     cb->nlh->nlmsg_seq,
+				     RTM_NEWROUTE, NLM_F_MULTI) < 0)
+			break;
+	}
+
+	rcu_read_unlock();
+	cb->args[0] = idx;
+
+	return skb->len;
+}
+
+/* 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);
+	INIT_HLIST_HEAD(&ns->binds);
+	mutex_init(&ns->bind_lock);
+	INIT_HLIST_HEAD(&ns->keys);
+	spin_lock_init(&ns->keys_lock);
+	WARN_ON(mctp_default_net_set(net, MCTP_INITIAL_DEFAULT_NET));
+	return 0;
+}
+
+static void __net_exit mctp_routes_net_exit(struct net *net)
+{
+	struct mctp_route *rt;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(rt, &net->mctp.routes, list)
+		mctp_route_release(rt);
+	rcu_read_unlock();
+}
+
+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);
+
+	rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_GETROUTE,
+			     NULL, mctp_dump_rtinfo, 0);
+	rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_NEWROUTE,
+			     mctp_newroute, NULL, 0);
+	rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_DELROUTE,
+			     mctp_delroute, NULL, 0);
+
+	return register_pernet_subsys(&mctp_net_ops);
+}
+
+void mctp_routes_exit(void)
+{
+	unregister_pernet_subsys(&mctp_net_ops);
+	rtnl_unregister(PF_MCTP, RTM_DELROUTE);
+	rtnl_unregister(PF_MCTP, RTM_NEWROUTE);
+	rtnl_unregister(PF_MCTP, RTM_GETROUTE);
+	dev_remove_pack(&mctp_packet_type);
+}
+
+#if IS_ENABLED(CONFIG_MCTP_TEST)
+#include "test/route-test.c"
+#endif