path: root/net/rxrpc/input.c

/* RxRPC packet reception
 *
 * 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 <linux/gfp.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <net/ip.h>
#include <net/udp.h>
#include <net/net_namespace.h>
#include "ar-internal.h"

/*
 * queue a packet for recvmsg to pass to userspace
 * - the caller must hold a lock on call->lock
 * - must not be called with interrupts disabled (sk_filter() disables BH's)
 * - eats the packet whether successful or not
 * - there must be just one reference to the packet, which the caller passes to
 *   this function
 */
int rxrpc_queue_rcv_skb(struct rxrpc_call *call, struct sk_buff *skb,
			bool force, bool terminal)
{
	struct rxrpc_skb_priv *sp;
	struct rxrpc_sock *rx = call->socket;
	struct sock *sk;
	int ret;

	_enter(",,%d,%d", force, terminal);

	ASSERT(!irqs_disabled());

	sp = rxrpc_skb(skb);
	ASSERTCMP(sp->call, ==, call);

	/* if we've already posted the terminal message for a call, then we
	 * don't post any more */
	if (test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags)) {
		_debug("already terminated");
		ASSERTCMP(call->state, >=, RXRPC_CALL_COMPLETE);
		skb->destructor = NULL;
		sp->call = NULL;
		rxrpc_put_call(call);
		rxrpc_free_skb(skb);
		return 0;
	}

	sk = &rx->sk;

	if (!force) {
		/* cast skb->rcvbuf to unsigned...  It's pointless, but
		 * reduces number of warnings when compiling with -W
		 * --ANK */
//		ret = -ENOBUFS;
//		if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
//		    (unsigned int) sk->sk_rcvbuf)
//			goto out;

		ret = sk_filter(sk, skb);
		if (ret < 0)
			goto out;
	}

	spin_lock_bh(&sk->sk_receive_queue.lock);
	if (!test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags) &&
	    !test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
	    call->socket->sk.sk_state != RXRPC_CLOSE) {
		skb->destructor = rxrpc_packet_destructor;
		skb->dev = NULL;
		skb->sk = sk;
		atomic_add(skb->truesize, &sk->sk_rmem_alloc);

		if (terminal) {
			_debug("<<<< TERMINAL MESSAGE >>>>");
			set_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags);
		}

		/* allow interception by a kernel service */
		if (rx->interceptor) {
			rx->interceptor(sk, call->user_call_ID, skb);
			spin_unlock_bh(&sk->sk_receive_queue.lock);
		} else {
			_net("post skb %p", skb);
			__skb_queue_tail(&sk->sk_receive_queue, skb);
			spin_unlock_bh(&sk->sk_receive_queue.lock);

			if (!sock_flag(sk, SOCK_DEAD))
				sk->sk_data_ready(sk);
		}
		skb = NULL;
	} else {
		spin_unlock_bh(&sk->sk_receive_queue.lock);
	}
	ret = 0;

out:
	/* release the socket buffer */
	if (skb) {
		skb->destructor = NULL;
		sp->call = NULL;
		rxrpc_put_call(call);
		rxrpc_free_skb(skb);
	}

	_leave(" = %d", ret);
	return ret;
}

/*
 * process a DATA packet, posting the packet to the appropriate queue
 * - eats the packet if successful
 */
static int rxrpc_fast_process_data(struct rxrpc_call *call,
				   struct sk_buff *skb, u32 seq)
{
	struct rxrpc_skb_priv *sp;
	bool terminal;
	int ret, ackbit, ack;

	_enter("{%u,%u},,{%u}", call->rx_data_post, call->rx_first_oos, seq);

	sp = rxrpc_skb(skb);
	ASSERTCMP(sp->call, ==, NULL);

	spin_lock(&call->lock);

	if (call->state > RXRPC_CALL_COMPLETE)
		goto discard;

	ASSERTCMP(call->rx_data_expect, >=, call->rx_data_post);
	ASSERTCMP(call->rx_data_post, >=, call->rx_data_recv);
	ASSERTCMP(call->rx_data_recv, >=, call->rx_data_eaten);

	if (seq < call->rx_data_post) {
		_debug("dup #%u [-%u]", seq, call->rx_data_post);
		ack = RXRPC_ACK_DUPLICATE;
		ret = -ENOBUFS;
		goto discard_and_ack;
	}

	/* we may already have the packet in the out of sequence queue */
	ackbit = seq - (call->rx_data_eaten + 1);
	ASSERTCMP(ackbit, >=, 0);
	if (__test_and_set_bit(ackbit, call->ackr_window)) {
		_debug("dup oos #%u [%u,%u]",
		       seq, call->rx_data_eaten, call->rx_data_post);
		ack = RXRPC_ACK_DUPLICATE;
		goto discard_and_ack;
	}

	if (seq >= call->ackr_win_top) {
		_debug("exceed #%u [%u]", seq, call->ackr_win_top);
		__clear_bit(ackbit, call->ackr_window);
		ack = RXRPC_ACK_EXCEEDS_WINDOW;
		goto discard_and_ack;
	}

	if (seq == call->rx_data_expect) {
		clear_bit(RXRPC_CALL_EXPECT_OOS, &call->flags);
		call->rx_data_expect++;
	} else if (seq > call->rx_data_expect) {
		_debug("oos #%u [%u]", seq, call->rx_data_expect);
		call->rx_data_expect = seq + 1;
		if (test_and_set_bit(RXRPC_CALL_EXPECT_OOS, &call->flags)) {
			ack = RXRPC_ACK_OUT_OF_SEQUENCE;
			goto enqueue_and_ack;
		}
		goto enqueue_packet;
	}

	if (seq != call->rx_data_post) {
		_debug("ahead #%u [%u]", seq, call->