1 files changed, 315 insertions, 0 deletions

diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c
new file mode 100644
index 000000000000..538e9831c699
--- /dev/null
+++ b/net/rxrpc/peer_object.c
@@ -0,0 +1,315 @@
+/* RxRPC remote transport endpoint record management
+ *
+ * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <linux/udp.h>
+#include <linux/in.h>
+#include <linux/slab.h>
+#include <linux/hashtable.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include <net/ip.h>
+#include <net/route.h>
+#include "ar-internal.h"
+
+static DEFINE_HASHTABLE(rxrpc_peer_hash, 10);
+static DEFINE_SPINLOCK(rxrpc_peer_hash_lock);
+
+/*
+ * Hash a peer key.
+ */
+static unsigned long rxrpc_peer_hash_key(struct rxrpc_local *local,
+					 const struct sockaddr_rxrpc *srx)
+{
+	const u16 *p;
+	unsigned int i, size;
+	unsigned long hash_key;
+
+	_enter("");
+
+	hash_key = (unsigned long)local / __alignof__(*local);
+	hash_key += srx->transport_type;
+	hash_key += srx->transport_len;
+	hash_key += srx->transport.family;
+
+	switch (srx->transport.family) {
+	case AF_INET:
+		hash_key += (u16 __force)srx->transport.sin.sin_port;
+		size = sizeof(srx->transport.sin.sin_addr);
+		p = (u16 *)&srx->transport.sin.sin_addr;
+		break;
+	default:
+		WARN(1, "AF_RXRPC: Unsupported transport address family\n");
+		return 0;
+	}
+
+	/* Step through the peer address in 16-bit portions for speed */
+	for (i = 0; i < size; i += sizeof(*p), p++)
+		hash_key += *p;
+
+	_leave(" 0x%lx", hash_key);
+	return hash_key;
+}
+
+/*
+ * Compare a peer to a key.  Return -ve, 0 or +ve to indicate less than, same
+ * or greater than.
+ *
+ * Unfortunately, the primitives in linux/hashtable.h don't allow for sorted
+ * buckets and mid-bucket insertion, so we don't make full use of this
+ * information at this point.
+ */
+static long rxrpc_peer_cmp_key(const struct rxrpc_peer *peer,
+			       struct rxrpc_local *local,
+			       const struct sockaddr_rxrpc *srx,
+			       unsigned long hash_key)
+{
+	long diff;
+
+	diff = ((peer->hash_key - hash_key) ?:
+		((unsigned long)peer->local - (unsigned long)local) ?:
+		(peer->srx.transport_type - srx->transport_type) ?:
+		(peer->srx.transport_len - srx->transport_len) ?:
+		(peer->srx.transport.family - srx->transport.family));
+	if (diff != 0)
+		return diff;
+
+	switch (srx->transport.family) {
+	case AF_INET:
+		return ((u16 __force)peer->srx.transport.sin.sin_port -
+			(u16 __force)srx->transport.sin.sin_port) ?:
+			memcmp(&peer->srx.transport.sin.sin_addr,
+			       &srx->transport.sin.sin_addr,
+			       sizeof(struct in_addr));
+	default:
+		BUG();
+	}
+}
+
+/*
+ * Look up a remote transport endpoint for the specified address using RCU.
+ */
+static struct rxrpc_peer *__rxrpc_lookup_peer_rcu(
+	struct rxrpc_local *local,
+	const struct sockaddr_rxrpc *srx,
+	unsigned long hash_key)
+{
+	struct rxrpc_peer *peer;
+
+	hash_for_each_possible_rcu(rxrpc_peer_hash, peer, hash_link, hash_key) {
+		if (rxrpc_peer_cmp_key(peer, local, srx, hash_key) == 0) {
+			if (atomic_read(&peer->usage) == 0)
+				return NULL;
+			return peer;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * Look up a remote transport endpoint for the specified address using RCU.
+ */
+struct rxrpc_peer *rxrpc_lookup_peer_rcu(struct rxrpc_local *local,
+					 const struct sockaddr_rxrpc *srx)
+{
+	struct rxrpc_peer *peer;
+	unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
+
+	peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
+	if (peer) {
+		switch (srx->transport.family) {
+		case AF_INET:
+			_net("PEER %d {%d,%u,%pI4+%hu}",
+			     peer->debug_id,
+			     peer->srx.transport_type,
+			     peer->srx.transport.family,
+			     &peer->srx.transport.sin.sin_addr,
+			     ntohs(peer->srx.transport.sin.sin_port));
+			break;
+		}
+
+		_leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
+	}
+	return peer;
+}
+
+/*
+ * assess the MTU size for the network interface through which this peer is
+ * reached
+ */
+static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
+{
+	struct rtable *rt;
+	struct flowi4 fl4;
+
+	peer->if_mtu = 1500;
+
+	rt = ip_route_output_ports(&init_net, &fl4, NULL,
+				   peer->srx.transport.sin.sin_addr.s_addr, 0,
+				   htons(7000), htons(7001),
+				   IPPROTO_UDP, 0, 0);
+	if (IS_ERR(rt)) {
+		_leave(" [route err %ld]", PTR_ERR(rt));
+		return;
+	}
+
+	peer->if_mtu = dst_mtu(&rt->dst);
+	dst_release(&rt->dst);
+
+	_leave(" [if_mtu %u]", peer->if_mtu);
+}
+
+/*
+ * Allocate a peer.
+ */
+struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp)
+{
+	struct rxrpc_peer *peer;
+
+	_enter("");
+
+	peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
+	if (peer) {
+		atomic_set(&peer->usage, 1);
+		peer->local = local;
+		INIT_HLIST_HEAD(&peer->error_targets);
+		INIT_WORK(&peer->error_distributor,
+			  &rxrpc_peer_error_distributor);
+		peer->service_conns = RB_ROOT;
+		seqlock_init(&peer->service_conn_lock);
+		spin_lock_init(&peer->lock);
+		peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
+	}
+
+	_leave(" = %p", peer);
+	return peer;
+}
+
+/*
+ * Set up a new peer.
+ */
+static struct rxrpc_peer *rxrpc_create_peer(struct rxrpc_local *local,
+					    struct sockaddr_rxrpc *srx,
+					    unsigned long hash_key,
+					    gfp_t gfp)
+{
+	struct rxrpc_peer *peer;
+
+	_enter("");
+
+	peer = rxrpc_alloc_peer(local, gfp);
+	if (peer) {
+		peer->hash_key = hash_key;
+		memcpy(&peer->srx, srx, sizeof(*srx));
+
+		rxrpc_assess_MTU_size(peer);
+		peer->mtu = peer->if_mtu;
+
+		if (srx->transport.family == AF_INET) {
+			peer->hdrsize = sizeof(struct iphdr);
+			switch (srx->transport_type) {
+			case SOCK_DGRAM:
+				peer->hdrsize += sizeof(struct udphdr);
+				break;
+			default:
+				BUG();
+				break;
+			}
+		} else {
+			BUG();
+		}
+
+		peer->hdrsize += sizeof(struct rxrpc_wire_header);
+		peer->maxdata = peer->mtu - peer->hdrsize;
+	}
+
+	_leave(" = %p", peer);
+	return peer;
+}
+
+/*
+ * obtain a remote transport endpoint for the specified address
+ */
+struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *local,
+				     struct sockaddr_rxrpc *srx, gfp_t gfp)
+{
+	struct rxrpc_peer *peer, *candidate;
+	unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
+
+	_enter("{%d,%d,%pI4+%hu}",
+	       srx->transport_type,
+	       srx->transport_len,
+	       &srx->transport.sin.sin_addr,
+	       ntohs(srx->transport.sin.sin_port));
+
+	/* search the peer list first */
+	rcu_read_lock();
+	peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
+	if (peer && !rxrpc_get_peer_maybe(peer))
+		peer = NULL;
+	rcu_read_unlock();
+
+	if (!peer) {
+		/* The peer is not yet present in hash - create a candidate
+		 * for a new record and then redo the search.
+		 */
+		candidate = rxrpc_create_peer(local, srx, hash_key, gfp);
+		if (!candidate) {
+			_leave(" = NULL [nomem]");
+			return NULL;
+		}
+
+		spin_lock(&rxrpc_peer_hash_lock);
+
+		/* Need to check that we aren't racing with someone else */
+		peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
+		if (peer && !rxrpc_get_peer_maybe(peer))
+			peer = NULL;
+		if (!peer)
+			hash_add_rcu(rxrpc_peer_hash,
+				     &candidate->hash_link, hash_key);
+
+		spin_unlock(&rxrpc_peer_hash_lock);
+
+		if (peer)
+			kfree(candidate);
+		else
+			peer = candidate;
+	}
+
+	_net("PEER %d {%d,%pI4+%hu}",
+	     peer->debug_id,
+	     peer->srx.transport_type,
+	     &peer->srx.transport.sin.sin_addr,
+	     ntohs(peer->srx.transport.sin.sin_port));
+
+	_leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
+	return peer;
+}
+
+/*
+ * Discard a ref on a remote peer record.
+ */
+void __rxrpc_put_peer(struct rxrpc_peer *peer)
+{
+	ASSERT(hlist_empty(&peer->error_targets));
+
+	spin_lock(&rxrpc_peer_hash_lock);
+	hash_del_rcu(&peer->hash_link);
+	spin_unlock(&rxrpc_peer_hash_lock);
+
+	kfree_rcu(peer, rcu);
+}