/* connection-level event 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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/net.h>
  #include <linux/skbuff.h>
  #include <linux/errqueue.h>

  #include <net/sock.h>
  #include <net/af_rxrpc.h>
  #include <net/ip.h>
  #include "ar-internal.h"
  
  /*

   * Retransmit terminal ACK or ABORT of the previous call.
   */

  static void rxrpc_conn_retransmit_call(struct rxrpc_connection *conn,
  				       struct sk_buff *skb)

  {
  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
  	struct rxrpc_channel *chan;
  	struct msghdr msg;
  	struct kvec iov;
  	struct {
  		struct rxrpc_wire_header whdr;
  		union {
  			struct {
  				__be32 code;
  			} abort;
  			struct {
  				struct rxrpc_ackpacket ack;

  				u8 padding[3];

  				struct rxrpc_ackinfo info;
  			};
  		};
  	} __attribute__((packed)) pkt;
  	size_t len;
  	u32 serial, mtu, call_id;
  
  	_enter("%d", conn->debug_id);
  
  	chan = &conn->channels[sp->hdr.cid & RXRPC_CHANNELMASK];
  
  	/* If the last call got moved on whilst we were waiting to run, just
  	 * ignore this packet.
  	 */
  	call_id = READ_ONCE(chan->last_call);
  	/* Sync with __rxrpc_disconnect_call() */
  	smp_rmb();
  	if (call_id != sp->hdr.callNumber)
  		return;
  
  	msg.msg_name	= &conn->params.peer->srx.transport;
  	msg.msg_namelen	= conn->params.peer->srx.transport_len;
  	msg.msg_control	= NULL;
  	msg.msg_controllen = 0;
  	msg.msg_flags	= 0;
  
  	pkt.whdr.epoch		= htonl(sp->hdr.epoch);
  	pkt.whdr.cid		= htonl(sp->hdr.cid);
  	pkt.whdr.callNumber	= htonl(sp->hdr.callNumber);
  	pkt.whdr.seq		= 0;
  	pkt.whdr.type		= chan->last_type;
  	pkt.whdr.flags		= conn->out_clientflag;
  	pkt.whdr.userStatus	= 0;
  	pkt.whdr.securityIndex	= conn->security_ix;
  	pkt.whdr._rsvd		= 0;

  	pkt.whdr.serviceId	= htons(conn->service_id);

  
  	len = sizeof(pkt.whdr);
  	switch (chan->last_type) {
  	case RXRPC_PACKET_TYPE_ABORT:
  		pkt.abort.code	= htonl(chan->last_abort);
  		len += sizeof(pkt.abort);
  		break;
  
  	case RXRPC_PACKET_TYPE_ACK:
  		mtu = conn->params.peer->if_mtu;
  		mtu -= conn->params.peer->hdrsize;
  		pkt.ack.bufferSpace	= 0;
  		pkt.ack.maxSkew		= htons(skb->priority);
  		pkt.ack.firstPacket	= htonl(chan->last_seq);
  		pkt.ack.previousPacket	= htonl(chan->last_seq - 1);
  		pkt.ack.serial		= htonl(sp->hdr.serial);
  		pkt.ack.reason		= RXRPC_ACK_DUPLICATE;
  		pkt.ack.nAcks		= 0;
  		pkt.info.rxMTU		= htonl(rxrpc_rx_mtu);
  		pkt.info.maxMTU		= htonl(mtu);
  		pkt.info.rwind		= htonl(rxrpc_rx_window_size);
  		pkt.info.jumbo_max	= htonl(rxrpc_rx_jumbo_max);

  		pkt.whdr.flags		|= RXRPC_SLOW_START_OK;

  		len += sizeof(pkt.ack) + sizeof(pkt.info);
  		break;
  	}
  
  	/* Resync with __rxrpc_disconnect_call() and check that the last call
  	 * didn't get advanced whilst we were filling out the packets.
  	 */
  	smp_rmb();
  	if (READ_ONCE(chan->last_call) != call_id)
  		return;
  
  	iov.iov_base	= &pkt;
  	iov.iov_len	= len;
  
  	serial = atomic_inc_return(&conn->serial);
  	pkt.whdr.serial = htonl(serial);
  
  	switch (chan->last_type) {
  	case RXRPC_PACKET_TYPE_ABORT:

  		_proto("Tx ABORT %%%u { %d } [re]", serial, conn->abort_code);

  		break;
  	case RXRPC_PACKET_TYPE_ACK:

  		trace_rxrpc_tx_ack(NULL, serial, chan->last_seq, 0,
  				   RXRPC_ACK_DUPLICATE, 0);

  		_proto("Tx ACK %%%u [re]", serial);
  		break;
  	}
  
  	kernel_sendmsg(conn->params.local->socket, &msg, &iov, 1, len);
  	_leave("");
  	return;
  }
  
  /*

   * pass a connection-level abort onto all calls on that connection
   */

  static void rxrpc_abort_calls(struct rxrpc_connection *conn,

  			      enum rxrpc_call_completion compl)

  {
  	struct rxrpc_call *call;

  	int i;

  	_enter("{%d},%x", conn->debug_id, conn->abort_code);

  	spin_lock(&conn->channel_lock);

  	for (i = 0; i < RXRPC_MAXCALLS; i++) {
  		call = rcu_dereference_protected(
  			conn->channels[i].call,
  			lockdep_is_held(&conn->channel_lock));

  		if (call) {

  			if (compl == RXRPC_CALL_LOCALLY_ABORTED)
  				trace_rxrpc_abort("CON", call->cid,
  						  call->call_id, 0,

  						  conn->abort_code,
  						  conn->error);

  			if (rxrpc_set_call_completion(call, compl,

  						      conn->abort_code,
  						      conn->error))

  				rxrpc_notify_socket(call);

  		}

  	}

  	spin_unlock(&conn->channel_lock);

  	_leave("");
  }
  
  /*
   * generate a connection-level abort
   */
  static int rxrpc_abort_connection(struct rxrpc_connection *conn,

  				  int error, u32 abort_code)

  {

  	struct rxrpc_wire_header whdr;

  	struct msghdr msg;
  	struct kvec iov[2];
  	__be32 word;
  	size_t len;

  	u32 serial;

  	int ret;
  
  	_enter("%d,,%u,%u", conn->debug_id, error, abort_code);
  
  	/* generate a connection-level abort */
  	spin_lock_bh(&conn->state_lock);

  	if (conn->state >= RXRPC_CONN_REMOTELY_ABORTED) {

  		spin_unlock_bh(&conn->state_lock);
  		_leave(" = 0 [already dead]");
  		return 0;
  	}

  	conn->error = error;
  	conn->abort_code = abort_code;

  	conn->state = RXRPC_CONN_LOCALLY_ABORTED;
  	spin_unlock_bh(&conn->state_lock);

  	rxrpc_abort_calls(conn, RXRPC_CALL_LOCALLY_ABORTED);

  	msg.msg_name	= &conn->params.peer->srx.transport;
  	msg.msg_namelen	= conn->params.peer->srx.transport_len;

  	msg.msg_control	= NULL;
  	msg.msg_controllen = 0;
  	msg.msg_flags	= 0;

  	whdr.epoch	= htonl(conn->proto.epoch);
  	whdr.cid	= htonl(conn->proto.cid);

  	whdr.callNumber	= 0;
  	whdr.seq	= 0;
  	whdr.type	= RXRPC_PACKET_TYPE_ABORT;
  	whdr.flags	= conn->out_clientflag;
  	whdr.userStatus	= 0;
  	whdr.securityIndex = conn->security_ix;
  	whdr._rsvd	= 0;

  	whdr.serviceId	= htons(conn->service_id);

  	word		= htonl(conn->abort_code);

  	iov[0].iov_base	= &whdr;
  	iov[0].iov_len	= sizeof(whdr);

  	iov[1].iov_base	= &word;
  	iov[1].iov_len	= sizeof(word);
  
  	len = iov[0].iov_len + iov[1].iov_len;

  	serial = atomic_inc_return(&conn->serial);
  	whdr.serial = htonl(serial);

  	_proto("Tx CONN ABORT %%%u { %d }", serial, conn->abort_code);

  	ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);

  	if (ret < 0) {
  		_debug("sendmsg failed: %d", ret);
  		return -EAGAIN;
  	}
  
  	_leave(" = 0");
  	return 0;
  }
  
  /*
   * mark a call as being on a now-secured channel

   * - must be called with BH's disabled.

   */

  static void rxrpc_call_is_secure(struct rxrpc_call *call)

  {
  	_enter("%p", call);
  	if (call) {

  		write_lock_bh(&call->state_lock);
  		if (call->state == RXRPC_CALL_SERVER_SECURING) {
  			call->state = RXRPC_CALL_SERVER_ACCEPTING;
  			rxrpc_notify_socket(call);
  		}
  		write_unlock_bh(&call->state_lock);

  	}
  }
  
  /*
   * connection-level Rx packet processor
   */
  static int rxrpc_process_event(struct rxrpc_connection *conn,
  			       struct sk_buff *skb,
  			       u32 *_abort_code)
  {
  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);

  	__be32 wtmp;
  	u32 abort_code;

  	int loop, ret;

  	if (conn->state >= RXRPC_CONN_REMOTELY_ABORTED) {

  		_leave(" = -ECONNABORTED [%u]", conn->state);

  		return -ECONNABORTED;

  	}

  	_enter("{%d},{%u,%%%u},", conn->debug_id, sp->hdr.type, sp->hdr.serial);

  	switch (sp->hdr.type) {

  	case RXRPC_PACKET_TYPE_DATA:
  	case RXRPC_PACKET_TYPE_ACK:

  		rxrpc_conn_retransmit_call(conn, skb);

  		return 0;

  	case RXRPC_PACKET_TYPE_BUSY:
  		/* Just ignore BUSY packets for now. */
  		return 0;

  	case RXRPC_PACKET_TYPE_ABORT:

  		if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),

  				  &wtmp, sizeof(wtmp)) < 0) {
  			trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
  					      tracepoint_string("bad_abort"));

  			return -EPROTO;

  		}

  		abort_code = ntohl(wtmp);
  		_proto("Rx ABORT %%%u { ac=%d }", sp->hdr.serial, abort_code);

  		conn->error = -ECONNABORTED;
  		conn->abort_code = abort_code;

  		conn->state = RXRPC_CONN_REMOTELY_ABORTED;

  		rxrpc_abort_calls(conn, RXRPC_CALL_REMOTELY_ABORTED);

  		return -ECONNABORTED;
  
  	case RXRPC_PACKET_TYPE_CHALLENGE:

  		return conn->security->respond_to_challenge(conn, skb,
  							    _abort_code);

  
  	case RXRPC_PACKET_TYPE_RESPONSE:

  		ret = conn->security->verify_response(conn, skb, _abort_code);
  		if (ret < 0)
  			return ret;
  
  		ret = conn->security->init_connection_security(conn);
  		if (ret < 0)
  			return ret;

  		ret = conn->security->prime_packet_security(conn);
  		if (ret < 0)
  			return ret;

  		spin_lock(&conn->channel_lock);

  		spin_lock(&conn->state_lock);

  		if (conn->state == RXRPC_CONN_SERVICE_CHALLENGING) {
  			conn->state = RXRPC_CONN_SERVICE;

  			spin_unlock(&conn->state_lock);

  			for (loop = 0; loop < RXRPC_MAXCALLS; loop++)

  				rxrpc_call_is_secure(
  					rcu_dereference_protected(

  						conn->channels[loop].call,
  						lockdep_is_held(&conn->channel_lock)));

  		} else {
  			spin_unlock(&conn->state_lock);

  		}

  		spin_unlock(&conn->channel_lock);

  		return 0;
  
  	default:

  		trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
  				      tracepoint_string("bad_conn_pkt"));

  		return -EPROTO;
  	}
  }
  
  /*
   * set up security and issue a challenge
   */
  static void rxrpc_secure_connection(struct rxrpc_connection *conn)
  {
  	u32 abort_code;
  	int ret;
  
  	_enter("{%d}", conn->debug_id);
  
  	ASSERT(conn->security_ix != 0);

  	if (!conn->params.key) {

  		_debug("set up security");
  		ret = rxrpc_init_server_conn_security(conn);
  		switch (ret) {
  		case 0:
  			break;
  		case -ENOENT:
  			abort_code = RX_CALL_DEAD;
  			goto abort;
  		default:
  			abort_code = RXKADNOAUTH;
  			goto abort;
  		}
  	}

  	if (conn->security->issue_challenge(conn) < 0) {
  		abort_code = RX_CALL_DEAD;
  		ret = -ENOMEM;
  		goto abort;
  	}
  
  	_leave("");
  	return;
  
  abort:
  	_debug("abort %d, %d", ret, abort_code);

  	rxrpc_abort_connection(conn, ret, abort_code);

  	_leave(" [aborted]");
  }
  
  /*
   * connection-level event processor
   */
  void rxrpc_process_connection(struct work_struct *work)
  {
  	struct rxrpc_connection *conn =
  		container_of(work, struct rxrpc_connection, processor);

  	struct sk_buff *skb;
  	u32 abort_code = RX_PROTOCOL_ERROR;
  	int ret;

  	rxrpc_see_connection(conn);

  	if (test_and_clear_bit(RXRPC_CONN_EV_CHALLENGE, &conn->events))

  		rxrpc_secure_connection(conn);

  
  	/* go through the conn-level event packets, releasing the ref on this
  	 * connection that each one has when we've finished with it */
  	while ((skb = skb_dequeue(&conn->rx_queue))) {

  		rxrpc_see_skb(skb, rxrpc_skb_rx_seen);

  		ret = rxrpc_process_event(conn, skb, &abort_code);
  		switch (ret) {
  		case -EPROTO:
  		case -EKEYEXPIRED:
  		case -EKEYREJECTED:
  			goto protocol_error;

  		case -ENOMEM:

  		case -EAGAIN:
  			goto requeue_and_leave;
  		case -ECONNABORTED:
  		default:

  			rxrpc_free_skb(skb, rxrpc_skb_rx_freed);

  			break;
  		}
  	}
  
  out:
  	rxrpc_put_connection(conn);
  	_leave("");
  	return;
  
  requeue_and_leave:
  	skb_queue_head(&conn->rx_queue, skb);
  	goto out;
  
  protocol_error:

  	if (rxrpc_abort_connection(conn, ret, abort_code) < 0)

  		goto requeue_and_leave;

  	rxrpc_free_skb(skb, rxrpc_skb_rx_freed);

  	goto out;
  }