text: // SPDX-License-Identifier: GPL-2.0-or-later
  /* connection-level event handling
   *
   * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   */
  
  #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,
  				       unsigned int channel)
  {
  	struct rxrpc_skb_priv *sp = skb ? rxrpc_skb(skb) : NULL;
  	struct rxrpc_channel *chan;
  	struct msghdr msg;
  	struct kvec iov[3];
  	struct {
  		struct rxrpc_wire_header whdr;
  		union {
  			__be32 abort_code;
  			struct rxrpc_ackpacket ack;
  		};
  	} __attribute__((packed)) pkt;
  	struct rxrpc_ackinfo ack_info;
  	size_t len;
  	int ret, ioc;
  	u32 serial, mtu, call_id, padding;
  
  	_enter("%d", conn->debug_id);
  
  	chan = &conn->channels[channel];
  
  	/* 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 (skb && 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;
  
  	iov[0].iov_base	= &pkt;
  	iov[0].iov_len	= sizeof(pkt.whdr);
  	iov[1].iov_base	= &padding;
  	iov[1].iov_len	= 3;
  	iov[2].iov_base	= &ack_info;
  	iov[2].iov_len	= sizeof(ack_info);
  
  	pkt.whdr.epoch		= htonl(conn->proto.epoch);
  	pkt.whdr.cid		= htonl(conn->proto.cid | channel);
  	pkt.whdr.callNumber	= htonl(call_id);
  	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);
  		iov[0].iov_len += sizeof(pkt.abort_code);
  		len += sizeof(pkt.abort_code);
  		ioc = 1;
  		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 ? skb->priority : 0);
  		pkt.ack.firstPacket	= htonl(chan->last_seq + 1);
  		pkt.ack.previousPacket	= htonl(chan->last_seq);
  		pkt.ack.serial		= htonl(skb ? sp->hdr.serial : 0);
  		pkt.ack.reason		= skb ? RXRPC_ACK_DUPLICATE : RXRPC_ACK_IDLE;
  		pkt.ack.nAcks		= 0;
  		ack_info.rxMTU		= htonl(rxrpc_rx_mtu);
  		ack_info.maxMTU		= htonl(mtu);
  		ack_info.rwind		= htonl(rxrpc_rx_window_size);
  		ack_info.jumbo_max	= htonl(rxrpc_rx_jumbo_max);
  		pkt.whdr.flags		|= RXRPC_SLOW_START_OK;
  		padding			= 0;
  		iov[0].iov_len += sizeof(pkt.ack);
  		len += sizeof(pkt.ack) + 3 + sizeof(ack_info);
  		ioc = 3;
  		break;
  
  	default:
  		return;
  	}
  
  	/* 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;
  
  	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(chan->call_debug_id, serial,
  				   ntohl(pkt.ack.firstPacket),
  				   ntohl(pkt.ack.serial),
  				   pkt.ack.reason, 0);
  		_proto("Tx ACK %%%u [re]", serial);
  		break;
  	}
  
  	ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, ioc, len);
  	conn->params.peer->last_tx_at = ktime_get_seconds();
  	if (ret < 0)
  		trace_rxrpc_tx_fail(chan->call_debug_id, serial, ret,
  				    rxrpc_tx_point_call_final_resend);
  	else
  		trace_rxrpc_tx_packet(chan->call_debug_id, &pkt.whdr,
  				      rxrpc_tx_point_call_final_resend);
  
  	_leave("");
  }
  
  /*
   * 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,
  			      rxrpc_serial_t serial)
  {
  	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(call->debug_id,
  						  "CON", call->cid,
  						  call->call_id, 0,
  						  conn->abort_code,
  						  conn->error);
  			else
  				trace_rxrpc_rx_abort(call, serial,
  						     conn->abort_code);
  			rxrpc_set_call_completion(call, compl,
  						  conn->abort_code,
  						  conn->error);
  		}
  	}
  
  	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);
  
  	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);
  	rxrpc_abort_calls(conn, RXRPC_CALL_LOCALLY_ABORTED, 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) {
  		trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
  				    rxrpc_tx_point_conn_abort);
  		_debug("sendmsg failed: %d", ret);
  		return -EAGAIN;
  	}
  
  	trace_rxrpc_tx_packet(conn->debug_id, &whdr, rxrpc_tx_point_conn_abort);
  
  	conn->params.peer->last_tx_at = ktime_get_seconds();
  
  	_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,
  					   sp->hdr.cid & RXRPC_CHANNELMASK);
  		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, sp->hdr.serial);
  		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);
  	ASSERT(conn->server_key);
  
  	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]");
  }
  
  /*
   * Process delayed final ACKs that we haven't subsumed into a subsequent call.
   */
  static void rxrpc_process_delayed_final_acks(struct rxrpc_connection *conn)
  {
  	unsigned long j = jiffies, next_j;
  	unsigned int channel;
  	bool set;
  
  again:
  	next_j = j + LONG_MAX;
  	set = false;
  	for (channel = 0; channel < RXRPC_MAXCALLS; channel++) {
  		struct rxrpc_channel *chan = &conn->channels[channel];
  		unsigned long ack_at;
  
  		if (!test_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags))
  			continue;
  
  		smp_rmb(); /* vs rxrpc_disconnect_client_call */
  		ack_at = READ_ONCE(chan->final_ack_at);
  
  		if (time_before(j, ack_at)) {
  			if (time_before(ack_at, next_j)) {
  				next_j = ack_at;
  				set = true;
  			}
  			continue;
  		}
  
  		if (test_and_clear_bit(RXRPC_CONN_FINAL_ACK_0 + channel,
  				       &conn->flags))
  			rxrpc_conn_retransmit_call(conn, NULL, channel);
  	}
  
  	j = jiffies;
  	if (time_before_eq(next_j, j))
  		goto again;
  	if (set)
  		rxrpc_reduce_conn_timer(conn, next_j);
  }
  
  /*
   * connection-level event processor
   */
  static void rxrpc_do_process_connection(struct rxrpc_connection *conn)
  {
  	struct sk_buff *skb;
  	u32 abort_code = RX_PROTOCOL_ERROR;
  	int ret;
  
  	if (test_and_clear_bit(RXRPC_CONN_EV_CHALLENGE, &conn->events))
  		rxrpc_secure_connection(conn);
  
  	/* Process delayed ACKs whose time has come. */
  	if (conn->flags & RXRPC_CONN_FINAL_ACK_MASK)
  		rxrpc_process_delayed_final_acks(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_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_freed);
  			break;
  		}
  	}
  
  	return;
  
  requeue_and_leave:
  	skb_queue_head(&conn->rx_queue, skb);
  	return;
  
  protocol_error:
  	if (rxrpc_abort_connection(conn, ret, abort_code) < 0)
  		goto requeue_and_leave;
  	rxrpc_free_skb(skb, rxrpc_skb_freed);
  	return;
  }
  
  void rxrpc_process_connection(struct work_struct *work)
  {
  	struct rxrpc_connection *conn =
  		container_of(work, struct rxrpc_connection, processor);
  
  	rxrpc_see_connection(conn);
  
  	if (__rxrpc_use_local(conn->params.local)) {
  		rxrpc_do_process_connection(conn);
  		rxrpc_unuse_local(conn->params.local);
  	}
  
  	rxrpc_put_connection(conn);
  	_leave("");
  	return;
  }
  