[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, 118 insertions, 0 deletions

diff --git a/net/rxrpc/ar-skbuff.c b/net/rxrpc/ar-skbuff.c
new file mode 100644
index 00000000000..d73f6fc7601
--- /dev/null
+++ b/net/rxrpc/ar-skbuff.c
@@ -0,0 +1,118 @@
+/* ar-skbuff.c: socket buffer destruction handling
+ *
+ * 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"
+
+/*
+ * set up for the ACK at the end of the receive phase when we discard the final
+ * receive phase data packet
+ * - called with softirqs disabled
+ */
+static void rxrpc_request_final_ACK(struct rxrpc_call *call)
+{
+	/* the call may be aborted before we have a chance to ACK it */
+	write_lock(&call->state_lock);
+
+	switch (call->state) {
+	case RXRPC_CALL_CLIENT_RECV_REPLY:
+		call->state = RXRPC_CALL_CLIENT_FINAL_ACK;
+		_debug("request final ACK");
+
+		/* get an extra ref on the call for the final-ACK generator to
+		 * release */
+		rxrpc_get_call(call);
+		set_bit(RXRPC_CALL_ACK_FINAL, &call->events);
+		if (try_to_del_timer_sync(&call->ack_timer) >= 0)
+			schedule_work(&call->processor);
+		break;
+
+	case RXRPC_CALL_SERVER_RECV_REQUEST:
+		call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
+	default:
+		break;
+	}
+
+	write_unlock(&call->state_lock);
+}
+
+/*
+ * drop the bottom ACK off of the call ACK window and advance the window
+ */
+static void rxrpc_hard_ACK_data(struct rxrpc_call *call,
+				struct rxrpc_skb_priv *sp)
+{
+	int loop;
+	u32 seq;
+
+	spin_lock_bh(&call->lock);
+
+	_debug("hard ACK #%u", ntohl(sp->hdr.seq));
+
+	for (loop = 0; loop < RXRPC_ACKR_WINDOW_ASZ; loop++) {
+		call->ackr_window[loop] >>= 1;
+		call->ackr_window[loop] |=
+			call->ackr_window[loop + 1] << (BITS_PER_LONG - 1);
+	}
+
+	seq = ntohl(sp->hdr.seq);
+	ASSERTCMP(seq, ==, call->rx_data_eaten + 1);
+	call->rx_data_eaten = seq;
+
+	if (call->ackr_win_top < UINT_MAX)
+		call->ackr_win_top++;
+
+	ASSERTIFCMP(call->state <= RXRPC_CALL_COMPLETE,
+		    call->rx_data_post, >=, call->rx_data_recv);
+	ASSERTIFCMP(call->state <= RXRPC_CALL_COMPLETE,
+		    call->rx_data_recv, >=, call->rx_data_eaten);
+
+	if (sp->hdr.flags & RXRPC_LAST_PACKET) {
+		rxrpc_request_final_ACK(call);
+	} else if (atomic_dec_and_test(&call->ackr_not_idle) &&
+		   test_and_clear_bit(RXRPC_CALL_TX_SOFT_ACK, &call->flags)) {
+		_debug("send Rx idle ACK");
+		__rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, sp->hdr.serial,
+				    true);
+	}
+
+	spin_unlock_bh(&call->lock);
+}
+
+/*
+ * destroy a packet that has an RxRPC control buffer
+ * - advance the hard-ACK state of the parent call (done here in case something
+ *   in the kernel bypasses recvmsg() and steals the packet directly off of the
+ *   socket receive queue)
+ */
+void rxrpc_packet_destructor(struct sk_buff *skb)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	struct rxrpc_call *call = sp->call;
+
+	_enter("%p{%p}", skb, call);
+
+	if (call) {
+		/* send the final ACK on a client call */
+		if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
+			rxrpc_hard_ACK_data(call, sp);
+		rxrpc_put_call(call);
+		sp->call = NULL;
+	}
+
+	if (skb->sk)
+		sock_rfree(skb);
+	_leave("");
+}