[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both

Provide AF_RXRPC sockets that can be used to talk to AFS servers, or serve
answers to AFS clients.  KerberosIV security is fully supported.  The patches
and some example test programs can be found in:

	http://people.redhat.com/~dhowells/rxrpc/

This will eventually replace the old implementation of kernel-only RxRPC
currently resident in net/rxrpc/.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 276 insertions, 0 deletions

diff --git a/net/rxrpc/ar-transport.c b/net/rxrpc/ar-transport.c
new file mode 100644
index 0000000..9b4e5cb
--- /dev/null
+++ b/net/rxrpc/ar-transport.c
@@ -0,0 +1,276 @@
+/* RxRPC point-to-point transport session management
+ *
+ * Copyright (C) 2007 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.
+ */
+
+#include <linux/module.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include "ar-internal.h"
+
+static void rxrpc_transport_reaper(struct work_struct *work);
+
+static LIST_HEAD(rxrpc_transports);
+static DEFINE_RWLOCK(rxrpc_transport_lock);
+static unsigned long rxrpc_transport_timeout = 3600 * 24;
+static DECLARE_DELAYED_WORK(rxrpc_transport_reap, rxrpc_transport_reaper);
+
+/*
+ * allocate a new transport session manager
+ */
+static struct rxrpc_transport *rxrpc_alloc_transport(struct rxrpc_local *local,
+						     struct rxrpc_peer *peer,
+						     gfp_t gfp)
+{
+	struct rxrpc_transport *trans;
+
+	_enter("");
+
+	trans = kzalloc(sizeof(struct rxrpc_transport), gfp);
+	if (trans) {
+		trans->local = local;
+		trans->peer = peer;
+		INIT_LIST_HEAD(&trans->link);
+		trans->bundles = RB_ROOT;
+		trans->client_conns = RB_ROOT;
+		trans->server_conns = RB_ROOT;
+		skb_queue_head_init(&trans->error_queue);
+		spin_lock_init(&trans->client_lock);
+		rwlock_init(&trans->conn_lock);
+		atomic_set(&trans->usage, 1);
+		trans->debug_id = atomic_inc_return(&rxrpc_debug_id);
+
+		if (peer->srx.transport.family == AF_INET) {
+			switch (peer->srx.transport_type) {
+			case SOCK_DGRAM:
+				INIT_WORK(&trans->error_handler,
+					  rxrpc_UDP_error_handler);
+				break;
+			default:
+				BUG();
+				break;
+			}
+		} else {
+			BUG();
+		}
+	}
+
+	_leave(" = %p", trans);
+	return trans;
+}
+
+/*
+ * obtain a transport session for the nominated endpoints
+ */
+struct rxrpc_transport *rxrpc_get_transport(struct rxrpc_local *local,
+					    struct rxrpc_peer *peer,
+					    gfp_t gfp)
+{
+	struct rxrpc_transport *trans, *candidate;
+	const char *new = "old";
+	int usage;
+
+	_enter("{%u.%u.%u.%u+%hu},{%u.%u.%u.%u+%hu},",
+	       NIPQUAD(local->srx.transport.sin.sin_addr),
+	       ntohs(local->srx.transport.sin.sin_port),
+	       NIPQUAD(peer->srx.transport.sin.sin_addr),
+	       ntohs(peer->srx.transport.sin.sin_port));
+
+	/* search the transport list first */
+	read_lock_bh(&rxrpc_transport_lock);
+	list_for_each_entry(trans, &rxrpc_transports, link) {
+		if (trans->local == local && trans->peer == peer)
+			goto found_extant_transport;
+	}
+	read_unlock_bh(&rxrpc_transport_lock);
+
+	/* not yet present - create a candidate for a new record and then
+	 * redo the search */
+	candidate = rxrpc_alloc_transport(local, peer, gfp);
+	if (!candidate) {
+		_leave(" = -ENOMEM");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	write_lock_bh(&rxrpc_transport_lock);
+
+	list_for_each_entry(trans, &rxrpc_transports, link) {
+		if (trans->local == local && trans->peer == peer)
+			goto found_extant_second;
+	}
+
+	/* we can now add the new candidate to the list */
+	trans = candidate;
+	candidate = NULL;
+
+	rxrpc_get_local(trans->local);
+	atomic_inc(&trans->peer->usage);
+	list_add_tail(&trans->link, &rxrpc_transports);
+	write_unlock_bh(&rxrpc_transport_lock);
+	new = "new";
+
+success:
+	_net("TRANSPORT %s %d local %d -> peer %d",
+	     new,
+	     trans->debug_id,
+	     trans->local->debug_id,
+	     trans->peer->debug_id);
+
+	_leave(" = %p {u=%d}", trans, atomic_read(&trans->usage));
+	return trans;
+
+	/* we found the transport in the list immediately */
+found_extant_transport:
+	usage = atomic_inc_return(&trans->usage);
+	read_unlock_bh(&rxrpc_transport_lock);
+	goto success;
+
+	/* we found the transport on the second time through the list */
+found_extant_second:
+	usage = atomic_inc_return(&trans->usage);
+	write_unlock_bh(&rxrpc_transport_lock);
+	kfree(candidate);
+	goto success;
+}
+
+/*
+ * find the transport connecting two endpoints
+ */
+struct rxrpc_transport *rxrpc_find_transport(struct rxrpc_local *local,
+					     struct rxrpc_peer *peer)
+{
+	struct rxrpc_transport *trans;
+
+	_enter("{%u.%u.%u.%u+%hu},{%u.%u.%u.%u+%hu},",
+	       NIPQUAD(local->srx.transport.sin.sin_addr),
+	       ntohs(local->srx.transport.sin.sin_port),
+	       NIPQUAD(peer->srx.transport.sin.sin_addr),
+	       ntohs(peer->srx.transport.sin.sin_port));
+
+	/* search the transport list */
+	read_lock_bh(&rxrpc_transport_lock);
+
+	list_for_each_entry(trans, &rxrpc_transports, link) {
+		if (trans->local == local && trans->peer == peer)
+			goto found_extant_transport;
+	}
+
+	read_unlock_bh(&rxrpc_transport_lock);
+	_leave(" = NULL");
+	return NULL;
+
+found_extant_transport:
+	atomic_inc(&trans->usage);
+	read_unlock_bh(&rxrpc_transport_lock);
+	_leave(" = %p", trans);
+	return trans;
+}
+
+/*
+ * release a transport session
+ */
+void rxrpc_put_transport(struct rxrpc_transport *trans)
+{
+	_enter("%p{u=%d}", trans, atomic_read(&trans->usage));
+
+	ASSERTCMP(atomic_read(&trans->usage), >, 0);
+
+	trans->put_time = xtime.tv_sec;
+	if (unlikely(atomic_dec_and_test(&trans->usage)))
+		_debug("zombie");
+		/* let the reaper determine the timeout to avoid a race with
+		 * overextending the timeout if the reaper is running at the
+		 * same time */
+		schedule_delayed_work(&rxrpc_transport_reap, 0);
+	_leave("");
+}
+
+/*
+ * clean up a transport session
+ */
+static void rxrpc_cleanup_transport(struct rxrpc_transport *trans)
+{
+	_net("DESTROY TRANS %d", trans->debug_id);
+
+	rxrpc_purge_queue(&trans->error_queue);
+
+	rxrpc_put_local(trans->local);
+	rxrpc_put_peer(trans->peer);
+	kfree(trans);
+}
+
+/*
+ * reap dead transports that have passed their expiry date
+ */
+static void rxrpc_transport_reaper(struct work_struct *work)
+{
+	struct rxrpc_transport *trans, *_p;
+	unsigned long now, earliest, reap_time;
+
+	LIST_HEAD(graveyard);
+
+	_enter("");
+
+	now = xtime.tv_sec;
+	earliest = ULONG_MAX;
+
+	/* extract all the transports that have been dead too long */
+	write_lock_bh(&rxrpc_transport_lock);
+	list_for_each_entry_safe(trans, _p, &rxrpc_transports, link) {
+		_debug("reap TRANS %d { u=%d t=%ld }",
+		       trans->debug_id, atomic_read(&trans->usage),
+		       (long) now - (long) trans->put_time);
+
+		if (likely(atomic_read(&trans->usage) > 0))
+			continue;
+
+		reap_time = trans->put_time + rxrpc_transport_timeout;
+		if (reap_time <= now)
+			list_move_tail(&trans->link, &graveyard);
+		else if (reap_time < earliest)
+			earliest = reap_time;
+	}
+	write_unlock_bh(&rxrpc_transport_lock);
+
+	if (earliest != ULONG_MAX) {
+		_debug("reschedule reaper %ld", (long) earliest - now);
+		ASSERTCMP(earliest, >, now);
+		schedule_delayed_work(&rxrpc_transport_reap,
+				      (earliest - now) * HZ);
+	}
+
+	/* then destroy all those pulled out */
+	while (!list_empty(&graveyard)) {
+		trans = list_entry(graveyard.next, struct rxrpc_transport,
+				   link);
+		list_del_init(&trans->link);
+
+		ASSERTCMP(atomic_read(&trans->usage), ==, 0);
+		rxrpc_cleanup_transport(trans);
+	}
+
+	_leave("");
+}
+
+/*
+ * preemptively destroy all the transport session records rather than waiting
+ * for them to time out
+ */
+void __exit rxrpc_destroy_all_transports(void)
+{
+	_enter("");
+
+	rxrpc_transport_timeout = 0;
+	cancel_delayed_work(&rxrpc_transport_reap);
+	schedule_delayed_work(&rxrpc_transport_reap, 0);
+
+	_leave("");
+}