[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, 273 insertions, 0 deletions

diff --git a/net/rxrpc/ar-peer.c b/net/rxrpc/ar-peer.c
new file mode 100644
index 000000000000..69ac355546ae
--- /dev/null
+++ b/net/rxrpc/ar-peer.c
@@ -0,0 +1,273 @@
+/* RxRPC remote transport endpoint 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 <linux/udp.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/icmp.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include <net/ip.h>
+#include "ar-internal.h"
+
+static LIST_HEAD(rxrpc_peers);
+static DEFINE_RWLOCK(rxrpc_peer_lock);
+static DECLARE_WAIT_QUEUE_HEAD(rxrpc_peer_wq);
+
+static void rxrpc_destroy_peer(struct work_struct *work);
+
+/*
+ * allocate a new peer
+ */
+static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
+					   gfp_t gfp)
+{
+	struct rxrpc_peer *peer;
+
+	_enter("");
+
+	peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
+	if (peer) {
+		INIT_WORK(&peer->destroyer, &rxrpc_destroy_peer);
+		INIT_LIST_HEAD(&peer->link);
+		INIT_LIST_HEAD(&peer->error_targets);
+		spin_lock_init(&peer->lock);
+		atomic_set(&peer->usage, 1);
+		peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
+		memcpy(&peer->srx, srx, sizeof(*srx));
+
+		peer->mtu = peer->if_mtu = 65535;
+
+		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_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_get_peer(struct sockaddr_rxrpc *srx, gfp_t gfp)
+{
+	struct rxrpc_peer *peer, *candidate;
+	const char *new = "old";
+	int usage;
+
+	_enter("{%d,%d,%u.%u.%u.%u+%hu}",
+	       srx->transport_type,
+	       srx->transport_len,
+	       NIPQUAD(srx->transport.sin.sin_addr),
+	       ntohs(srx->transport.sin.sin_port));
+
+	/* search the peer list first */
+	read_lock_bh(&rxrpc_peer_lock);
+	list_for_each_entry(peer, &rxrpc_peers, link) {
+		_debug("check PEER %d { u=%d t=%d l=%d }",
+		       peer->debug_id,
+		       atomic_read(&peer->usage),
+		       peer->srx.transport_type,
+		       peer->srx.transport_len);
+
+		if (atomic_read(&peer->usage) > 0 &&
+		    peer->srx.transport_type == srx->transport_type &&
+		    peer->srx.transport_len == srx->transport_len &&
+		    memcmp(&peer->srx.transport,
+			   &srx->transport,
+			   srx->transport_len) == 0)
+			goto found_extant_peer;
+	}
+	read_unlock_bh(&rxrpc_peer_lock);
+
+	/* not yet present - create a candidate for a new record and then
+	 * redo the search */
+	candidate = rxrpc_alloc_peer(srx, gfp);
+	if (!candidate) {
+		_leave(" = -ENOMEM");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	write_lock_bh(&rxrpc_peer_lock);
+
+	list_for_each_entry(peer, &rxrpc_peers, link) {
+		if (atomic_read(&peer->usage) > 0 &&
+		    peer->srx.transport_type == srx->transport_type &&
+		    peer->srx.transport_len == srx->transport_len &&
+		    memcmp(&peer->srx.transport,
+			   &srx->transport,
+			   srx->transport_len) == 0)
+			goto found_extant_second;
+	}
+
+	/* we can now add the new candidate to the list */
+	peer = candidate;
+	candidate = NULL;
+
+	list_add_tail(&peer->link, &rxrpc_peers);
+	write_unlock_bh(&rxrpc_peer_lock);
+	new = "new";
+
+success:
+	_net("PEER %s %d {%d,%u,%u.%u.%u.%u+%hu}",
+	     new,
+	     peer->debug_id,
+	     peer->srx.transport_type,
+	     peer->srx.transport.family,
+	     NIPQUAD(peer->srx.transport.sin.sin_addr),
+	     ntohs(peer->srx.transport.sin.sin_port));
+
+	_leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
+	return peer;
+
+	/* we found the peer in the list immediately */
+found_extant_peer:
+	usage = atomic_inc_return(&peer->usage);
+	read_unlock_bh(&rxrpc_peer_lock);
+	goto success;
+
+	/* we found the peer on the second time through the list */
+found_extant_second:
+	usage = atomic_inc_return(&peer->usage);
+	write_unlock_bh(&rxrpc_peer_lock);
+	kfree(candidate);
+	goto success;
+}
+
+/*
+ * find the peer associated with a packet
+ */
+struct rxrpc_peer *rxrpc_find_peer(struct rxrpc_local *local,
+				   __be32 addr, __be16 port)
+{
+	struct rxrpc_peer *peer;
+
+	_enter("");
+
+	/* search the peer list */
+	read_lock_bh(&rxrpc_peer_lock);
+
+	if (local->srx.transport.family == AF_INET &&
+	    local->srx.transport_type == SOCK_DGRAM
+	    ) {
+		list_for_each_entry(peer, &rxrpc_peers, link) {
+			if (atomic_read(&peer->usage) > 0 &&
+			    peer->srx.transport_type == SOCK_DGRAM &&
+			    peer->srx.transport.family == AF_INET &&
+			    peer->srx.transport.sin.sin_port == port &&
+			    peer->srx.transport.sin.sin_addr.s_addr == addr)
+				goto found_UDP_peer;
+		}
+
+		goto new_UDP_peer;
+	}
+
+	read_unlock_bh(&rxrpc_peer_lock);
+	_leave(" = -EAFNOSUPPORT");
+	return ERR_PTR(-EAFNOSUPPORT);
+
+found_UDP_peer:
+	_net("Rx UDP DGRAM from peer %d", peer->debug_id);
+	atomic_inc(&peer->usage);
+	read_unlock_bh(&rxrpc_peer_lock);
+	_leave(" = %p", peer);
+	return peer;
+
+new_UDP_peer:
+	_net("Rx UDP DGRAM from NEW peer %d", peer->debug_id);
+	read_unlock_bh(&rxrpc_peer_lock);
+	_leave(" = -EBUSY [new]");
+	return ERR_PTR(-EBUSY);
+}
+
+/*
+ * release a remote transport endpoint
+ */
+void rxrpc_put_peer(struct rxrpc_peer *peer)
+{
+	_enter("%p{u=%d}", peer, atomic_read(&peer->usage));
+
+	ASSERTCMP(atomic_read(&peer->usage), >, 0);
+
+	if (likely(!atomic_dec_and_test(&peer->usage))) {
+		_leave(" [in use]");
+		return;
+	}
+
+	schedule_work(&peer->destroyer);
+	_leave("");
+}
+
+/*
+ * destroy a remote transport endpoint
+ */
+static void rxrpc_destroy_peer(struct work_struct *work)
+{
+	struct rxrpc_peer *peer =
+		container_of(work, struct rxrpc_peer, destroyer);
+
+	_enter("%p{%d}", peer, atomic_read(&peer->usage));
+
+	write_lock_bh(&rxrpc_peer_lock);
+	list_del(&peer->link);
+	write_unlock_bh(&rxrpc_peer_lock);
+
+	_net("DESTROY PEER %d", peer->debug_id);
+	kfree(peer);
+
+	if (list_empty(&rxrpc_peers))
+		wake_up_all(&rxrpc_peer_wq);
+	_leave("");
+}
+
+/*
+ * preemptively destroy all the peer records from a transport endpoint rather
+ * than waiting for them to time out
+ */
+void __exit rxrpc_destroy_all_peers(void)
+{
+	DECLARE_WAITQUEUE(myself,current);
+
+	_enter("");
+
+	/* we simply have to wait for them to go away */
+	if (!list_empty(&rxrpc_peers)) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		add_wait_queue(&rxrpc_peer_wq, &myself);
+
+		while (!list_empty(&rxrpc_peers)) {
+			schedule();
+			set_current_state(TASK_UNINTERRUPTIBLE);
+		}
+
+		remove_wait_queue(&rxrpc_peer_wq, &myself);
+		set_current_state(TASK_RUNNING);
+	}
+
+	_leave("");
+}