/* 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 <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"

/*
 * pass a connection-level abort onto all calls on that connection
 */
static void rxrpc_abort_calls(struct rxrpc_connection *conn, int state,
			      u32 abort_code)
{
	struct rxrpc_call *call;
	struct rb_node *p;

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

	read_lock_bh(&conn->lock);

	for (p = rb_first(&conn->calls); p; p = rb_next(p)) {
		call = rb_entry(p, struct rxrpc_call, conn_node);
		write_lock(&call->state_lock);
		if (call->state <= RXRPC_CALL_COMPLETE) {
			call->state = state;
			if (state == RXRPC_CALL_LOCALLY_ABORTED) {
				call->local_abort = conn->local_abort;
				set_bit(RXRPC_CALL_EV_CONN_ABORT, &call->events);
			} else {
				call->remote_abort = conn->remote_abort;
				set_bit(RXRPC_CALL_EV_RCVD_ABORT, &call->events);
			}
			rxrpc_queue_call(call);
		}
		write_unlock(&call->state_lock);
	}

	read_unlock_bh(&conn->lock);
	_leave("");
}

/*
 * generate a connection-level abort
 */
static int rxrpc_abort_connection(struct rxrpc_connection *conn,
				  u32 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) {
		conn->state = RXRPC_CONN_LOCALLY_ABORTED;
		conn->error = error;
		spin_unlock_bh(&conn->state_lock);
	} else {
		spin_unlock_bh(&conn->state_lock);
		_leave(" = 0 [already dead]");
		return 0;
	}

	rxrpc_abort_calls(conn, RXRPC_CALL_LOCALLY_ABORTED, abort_code);

	msg.msg_name	= &conn->trans->peer->srx.transport;
	msg.msg_namelen	= conn->trans->peer->srx.transport_len;
	msg.msg_control	= NULL;
	msg.msg_controllen = 0;
	msg.msg_flags	= 0;

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

	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->local_abort);

	ret = kernel_sendmsg(conn->trans->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 softirqs disabled
 */
static void rxrpc_call_is_secure(struct rxrpc_call *call)
{
	_enter("%p", call);
	if (call) {
		read_lock(&call->state_lock);
		if (call->state < RXRPC_CALL_COMPLETE &&
		    !test_and_set_bit(RXRPC_CALL_EV_SECURED, &call->events))
			rxrpc_queue_call(call);
		read_unlock(&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) {
		kleave(" = -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_ABORT:
		if (skb_copy_bits(skb, 0, &wtmp, sizeof(wtmp)) < 0)
			return -EPROTO;
		abort_code = ntohl(wtmp);
		_proto("Rx ABORT %%%u { ac=%d }", sp->hdr.serial, abort_code);

		conn->state = RXRPC_CONN_REMOTELY_ABORTED;
		rxrpc_abort_calls(conn, RXRPC_CALL_REMOTELY_ABORTED,
				  abort_code);
		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;

		conn->security->prime_packet_security(conn);
		read_lock_bh(&conn->lock);
		spin_lock(&conn->state_lock);

		if (conn->state == RXRPC_CONN_SERVER_CHALLENGING) {
			conn->state = RXRPC_CONN_SERVER;
			for (loop = 0; loop < RXRPC_MAXCALLS; loop++)
				rxrpc_call_is_secure(conn->channels[loop]);
		}

		spin_unlock(&conn->state_lock);
		read_unlock_bh(&conn->lock);
		return 0;

	default:
		_leave(" = -EPROTO [%u]", sp->hdr.type);
		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->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;

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

	atomic_inc(&conn->usage);

	if (test_and_clear_bit(RXRPC_CONN_CHALLENGE, &conn->events)) {
		rxrpc_secure_connection(conn);
		rxrpc_put_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))) {
		ret = rxrpc_process_event(conn, skb, &abort_code);
		switch (ret) {
		case -EPROTO:
		case -EKEYEXPIRED:
		case -EKEYREJECTED:
			goto protocol_error;
		case -EAGAIN:
			goto requeue_and_leave;
		case -ECONNABORTED:
		default:
			rxrpc_put_connection(conn);
			rxrpc_free_skb(skb);
			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_put_connection(conn);
	rxrpc_free_skb(skb);
	_leave(" [EPROTO]");
	goto out;
}

/*
 * put a packet up for transport-level abort
 */
void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
{
	CHECK_SLAB_OKAY(&local->usage);

	skb_queue_tail(&local->reject_queue, skb);
	rxrpc_queue_work(&local->processor);
}

/*
 * reject packets through the local endpoint
 */
void rxrpc_reject_packets(struct rxrpc_local *local)
{
	union {
		struct sockaddr sa;
		struct sockaddr_in sin;
	} sa;
	struct rxrpc_skb_priv *sp;
	struct rxrpc_wire_header whdr;
	struct sk_buff *skb;
	struct msghdr msg;
	struct kvec iov[2];
	size_t size;
	__be32 code;

	_enter("%d", local->debug_id);

	iov[0].iov_base = &whdr;
	iov[0].iov_len = sizeof(whdr);
	iov[1].iov_base = &code;
	iov[1].iov_len = sizeof(code);
	size = sizeof(whdr) + sizeof(code);

	msg.msg_name = &sa;
	msg.msg_control = NULL;
	msg.msg_controllen = 0;
	msg.msg_flags = 0;

	memset(&sa, 0, sizeof(sa));
	sa.sa.sa_family = local->srx.transport.family;
	switch (sa.sa.sa_family) {
	case AF_INET:
		msg.msg_namelen = sizeof(sa.sin);
		break;
	default:
		msg.msg_namelen = 0;
		break;
	}

	memset(&whdr, 0, sizeof(whdr));
	whdr.type = RXRPC_PACKET_TYPE_ABORT;

	while ((skb = skb_dequeue(&local->reject_queue))) {
		sp = rxrpc_skb(skb);
		switch (sa.sa.sa_family) {
		case AF_INET:
			sa.sin.sin_port = udp_hdr(skb)->source;
			sa.sin.sin_addr.s_addr = ip_hdr(skb)->saddr;
			code = htonl(skb->priority);

			whdr.epoch	= htonl(sp->hdr.epoch);
			whdr.cid	= htonl(sp->hdr.cid);
			whdr.callNumber	= htonl(sp->hdr.callNumber);
			whdr.serviceId	= htons(sp->hdr.serviceId);
			whdr.flags	= sp->hdr.flags;
			whdr.flags	^= RXRPC_CLIENT_INITIATED;
			whdr.flags	&= RXRPC_CLIENT_INITIATED;

			kernel_sendmsg(local->socket, &msg, iov, 2, size);
			break;

		default:
			break;
		}

		rxrpc_free_skb(skb);
	}

	_leave("");
}