[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, 366 insertions, 0 deletions

diff --git a/net/rxrpc/ar-recvmsg.c b/net/rxrpc/ar-recvmsg.c
new file mode 100644
index 0000000..e947d5c
--- /dev/null
+++ b/net/rxrpc/ar-recvmsg.c
@@ -0,0 +1,366 @@
+/* RxRPC recvmsg() implementation
+ *
+ * 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/net.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include "ar-internal.h"
+
+/*
+ * removal a call's user ID from the socket tree to make the user ID available
+ * again and so that it won't be seen again in association with that call
+ */
+static void rxrpc_remove_user_ID(struct rxrpc_sock *rx, struct rxrpc_call *call)
+{
+	_debug("RELEASE CALL %d", call->debug_id);
+
+	if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
+		write_lock_bh(&rx->call_lock);
+		rb_erase(&call->sock_node, &call->socket->calls);
+		clear_bit(RXRPC_CALL_HAS_USERID, &call->flags);
+		write_unlock_bh(&rx->call_lock);
+	}
+
+	read_lock_bh(&call->state_lock);
+	if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
+	    !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
+		schedule_work(&call->processor);
+	read_unlock_bh(&call->state_lock);
+}
+
+/*
+ * receive a message from an RxRPC socket
+ * - we need to be careful about two or more threads calling recvmsg
+ *   simultaneously
+ */
+int rxrpc_recvmsg(struct kiocb *iocb, struct socket *sock,
+		  struct msghdr *msg, size_t len, int flags)
+{
+	struct rxrpc_skb_priv *sp;
+	struct rxrpc_call *call = NULL, *continue_call = NULL;
+	struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
+	struct sk_buff *skb;
+	long timeo;
+	int copy, ret, ullen, offset, copied = 0;
+	u32 abort_code;
+
+	DEFINE_WAIT(wait);
+
+	_enter(",,,%zu,%d", len, flags);
+
+	if (flags & (MSG_OOB | MSG_TRUNC))
+		return -EOPNOTSUPP;
+
+	ullen = msg->msg_flags & MSG_CMSG_COMPAT ? 4 : sizeof(unsigned long);
+
+	timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
+	msg->msg_flags |= MSG_MORE;
+
+	lock_sock(&rx->sk);
+
+	for (;;) {
+		/* return immediately if a client socket has no outstanding
+		 * calls */
+		if (RB_EMPTY_ROOT(&rx->calls)) {
+			if (copied)
+				goto out;
+			if (rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
+				release_sock(&rx->sk);
+				if (continue_call)
+					rxrpc_put_call(continue_call);
+				return -ENODATA;
+			}
+		}
+
+		/* get the next message on the Rx queue */
+		skb = skb_peek(&rx->sk.sk_receive_queue);
+		if (!skb) {
+			/* nothing remains on the queue */
+			if (copied &&
+			    (msg->msg_flags & MSG_PEEK || timeo == 0))
+				goto out;
+
+			/* wait for a message to turn up */
+			release_sock(&rx->sk);
+			prepare_to_wait_exclusive(rx->sk.sk_sleep, &wait,
+						  TASK_INTERRUPTIBLE);
+			ret = sock_error(&rx->sk);
+			if (ret)
+				goto wait_error;
+
+			if (skb_queue_empty(&rx->sk.sk_receive_queue)) {
+				if (signal_pending(current))
+					goto wait_interrupted;
+				timeo = schedule_timeout(timeo);
+			}
+			finish_wait(rx->sk.sk_sleep, &wait);
+			lock_sock(&rx->sk);
+			continue;
+		}
+
+	peek_next_packet:
+		sp = rxrpc_skb(skb);
+		call = sp->call;
+		ASSERT(call != NULL);
+
+		_debug("next pkt %s", rxrpc_pkts[sp->hdr.type]);
+
+		/* make sure we wait for the state to be updated in this call */
+		spin_lock_bh(&call->lock);
+		spin_unlock_bh(&call->lock);
+
+		if (test_bit(RXRPC_CALL_RELEASED, &call->flags)) {
+			_debug("packet from released call");
+			if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
+				BUG();
+			rxrpc_free_skb(skb);
+			continue;
+		}
+
+		/* determine whether to continue last data receive */
+		if (continue_call) {
+			_debug("maybe cont");
+			if (call != continue_call ||
+			    skb->mark != RXRPC_SKB_MARK_DATA) {
+				release_sock(&rx->sk);
+				rxrpc_put_call(continue_call);
+				_leave(" = %d [noncont]", copied);
+				return copied;
+			}
+		}
+
+		rxrpc_get_call(call);
+
+		/* copy the peer address and timestamp */
+		if (!continue_call) {
+			if (msg->msg_name && msg->msg_namelen > 0)
+				memcpy(&msg->msg_name, &call->conn->trans->peer->srx,
+				       sizeof(call->conn->trans->peer->srx));
+			sock_recv_timestamp(msg, &rx->sk, skb);
+		}
+
+		/* receive the message */
+		if (skb->mark != RXRPC_SKB_MARK_DATA)
+			goto receive_non_data_message;
+
+		_debug("recvmsg DATA #%u { %d, %d }",
+		       ntohl(sp->hdr.seq), skb->len, sp->offset);
+
+		if (!continue_call) {
+			/* only set the control data once per recvmsg() */
+			ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
+				       ullen, &call->user_call_ID);
+			if (ret < 0)
+				goto copy_error;
+			ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
+		}
+
+		ASSERTCMP(ntohl(sp->hdr.seq), >=, call->rx_data_recv);
+		ASSERTCMP(ntohl(sp->hdr.seq), <=, call->rx_data_recv + 1);
+		call->rx_data_recv = ntohl(sp->hdr.seq);
+
+		ASSERTCMP(ntohl(sp->hdr.seq), >, call->rx_data_eaten);
+
+		offset = sp->offset;
+		copy = skb->len - offset;
+		if (copy > len - copied)
+			copy = len - copied;
+
+		if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+			ret = skb_copy_datagram_iovec(skb, offset,
+						      msg->msg_iov, copy);
+		} else {
+			ret = skb_copy_and_csum_datagram_iovec(skb, offset,
+							       msg->msg_iov);
+			if (ret == -EINVAL)
+				goto csum_copy_error;
+		}
+
+		if (ret < 0)
+			goto copy_error;
+
+		/* handle piecemeal consumption of data packets */
+		_debug("copied %d+%d", copy, copied);
+
+		offset += copy;
+		copied += copy;
+
+		if (!(flags & MSG_PEEK))
+			sp->offset = offset;
+
+		if (sp->offset < skb->len) {
+			_debug("buffer full");
+			ASSERTCMP(copied, ==, len);
+			break;
+		}
+
+		/* we transferred the whole data packet */
+		if (sp->hdr.flags & RXRPC_LAST_PACKET) {
+			_debug("last");
+			if (call->conn->out_clientflag) {
+				 /* last byte of reply received */
+				ret = copied;
+				goto terminal_message;
+			}
+
+			/* last bit of request received */
+			if (!(flags & MSG_PEEK)) {
+				_debug("eat packet");
+				if (skb_dequeue(&rx->sk.sk_receive_queue) !=
+				    skb)
+					BUG();
+				rxrpc_free_skb(skb);
+			}
+			msg->msg_flags &= ~MSG_MORE;
+			break;
+		}
+
+		/* move on to the next data message */
+		_debug("next");
+		if (!continue_call)
+			continue_call = sp->call;
+		else
+			rxrpc_put_call(call);
+		call = NULL;
+
+		if (flags & MSG_PEEK) {
+			_debug("peek next");
+			skb = skb->next;
+			if (skb == (struct sk_buff *) &rx->sk.sk_receive_queue)
+				break;
+			goto peek_next_packet;
+		}
+
+		_debug("eat packet");
+		if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
+			BUG();
+		rxrpc_free_skb(skb);
+	}
+
+	/* end of non-terminal data packet reception for the moment */
+	_debug("end rcv data");
+out:
+	release_sock(&rx->sk);
+	if (call)
+		rxrpc_put_call(call);
+	if (continue_call)
+		rxrpc_put_call(continue_call);
+	_leave(" = %d [data]", copied);
+	return copied;
+
+	/* handle non-DATA messages such as aborts, incoming connections and
+	 * final ACKs */
+receive_non_data_message:
+	_debug("non-data");
+
+	if (skb->mark == RXRPC_SKB_MARK_NEW_CALL) {
+		_debug("RECV NEW CALL");
+		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &abort_code);
+		if (ret < 0)
+			goto copy_error;
+		if (!(flags & MSG_PEEK)) {
+			if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
+				BUG();
+			rxrpc_free_skb(skb);
+		}
+		goto out;
+	}
+
+	ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
+		       ullen, &call->user_call_ID);
+	if (ret < 0)
+		goto copy_error;
+	ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
+
+	switch (skb->mark) {
+	case RXRPC_SKB_MARK_DATA:
+		BUG();
+	case RXRPC_SKB_MARK_FINAL_ACK:
+		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &abort_code);
+		break;
+	case RXRPC_SKB_MARK_BUSY:
+		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_BUSY, 0, &abort_code);
+		break;
+	case RXRPC_SKB_MARK_REMOTE_ABORT:
+		abort_code = call->abort_code;
+		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &abort_code);
+		break;
+	case RXRPC_SKB_MARK_NET_ERROR:
+		_debug("RECV NET ERROR %d", sp->error);
+		abort_code = sp->error;
+		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &abort_code);
+		break;
+	case RXRPC_SKB_MARK_LOCAL_ERROR:
+		_debug("RECV LOCAL ERROR %d", sp->error);
+		abort_code = sp->error;
+		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4,
+			       &abort_code);
+		break;
+	default:
+		BUG();
+		break;
+	}
+
+	if (ret < 0)
+		goto copy_error;
+
+terminal_message:
+	_debug("terminal");
+	msg->msg_flags &= ~MSG_MORE;
+	msg->msg_flags |= MSG_EOR;
+
+	if (!(flags & MSG_PEEK)) {
+		_net("free terminal skb %p", skb);
+		if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
+			BUG();
+		rxrpc_free_skb(skb);
+		rxrpc_remove_user_ID(rx, call);
+	}
+
+	release_sock(&rx->sk);
+	rxrpc_put_call(call);
+	if (continue_call)
+		rxrpc_put_call(continue_call);
+	_leave(" = %d", ret);
+	return ret;
+
+copy_error:
+	_debug("copy error");
+	release_sock(&rx->sk);
+	rxrpc_put_call(call);
+	if (continue_call)
+		rxrpc_put_call(continue_call);
+	_leave(" = %d", ret);
+	return ret;
+
+csum_copy_error:
+	_debug("csum error");
+	release_sock(&rx->sk);
+	if (continue_call)
+		rxrpc_put_call(continue_call);
+	rxrpc_kill_skb(skb);
+	skb_kill_datagram(&rx->sk, skb, flags);
+	rxrpc_put_call(call);
+	return -EAGAIN;
+
+wait_interrupted:
+	ret = sock_intr_errno(timeo);
+wait_error:
+	finish_wait(rx->sk.sk_sleep, &wait);
+	if (continue_call)
+		rxrpc_put_call(continue_call);
+	if (copied)
+		copied = ret;
+	_leave(" = %d [waitfail %d]", copied, ret);
+	return copied;
+
+}