ar-error.c

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/* Error message handling (ICMP)
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * 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/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"

/*
 * handle an error received on the local endpoint
 */
void rxrpc_UDP_error_report(struct sock *sk)
{
    struct sock_exterr_skb *serr;
    struct rxrpc_transport *trans;
    struct rxrpc_local *local = sk->sk_user_data;
    struct rxrpc_peer *peer;
    struct sk_buff *skb;
    __be32 addr;
    __be16 port;

    _enter("%p{%d}", sk, local->debug_id);

    skb = skb_dequeue(&sk->sk_error_queue);
    if (!skb) {
        _leave("UDP socket errqueue empty");
        return;
    }

    rxrpc_new_skb(skb);

    serr = SKB_EXT_ERR(skb);
    addr = *(__be32 *)(skb_network_header(skb) + serr->addr_offset);
    port = serr->port;

    _net("Rx UDP Error from %pI4:%hu", &addr, ntohs(port));
    _debug("Msg l:%d d:%d", skb->len, skb->data_len);

    peer = rxrpc_find_peer(local, addr, port);
    if (IS_ERR(peer)) {
        rxrpc_free_skb(skb);
        _leave(" [no peer]");
        return;
    }

    trans = rxrpc_find_transport(local, peer);
    if (!trans) {
        rxrpc_put_peer(peer);
        rxrpc_free_skb(skb);
        _leave(" [no trans]");
        return;
    }

    if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP &&
        serr->ee.ee_type == ICMP_DEST_UNREACH &&
        serr->ee.ee_code == ICMP_FRAG_NEEDED
        ) {
        u32 mtu = serr->ee.ee_info;

        _net("Rx Received ICMP Fragmentation Needed (%d)", mtu);

        /* wind down the local interface MTU */
        if (mtu > 0 && peer->if_mtu == 65535 && mtu < peer->if_mtu) {
            peer->if_mtu = mtu;
            _net("I/F MTU %u", mtu);
        }

        if (mtu == 0) {
            /* they didn't give us a size, estimate one */
            if (mtu > 1500) {
                mtu >>= 1;
                if (mtu < 1500)
                    mtu = 1500;
            } else {
                mtu -= 100;
                if (mtu < peer->hdrsize)
                    mtu = peer->hdrsize + 4;
            }
        }

        if (mtu < peer->mtu) {
            spin_lock_bh(&peer->lock);
            peer->mtu = mtu;
            peer->maxdata = peer->mtu - peer->hdrsize;
            spin_unlock_bh(&peer->lock);
            _net("Net MTU %u (maxdata %u)",
                 peer->mtu, peer->maxdata);
        }
    }

    rxrpc_put_peer(peer);

    /* pass the transport ref to error_handler to release */
    skb_queue_tail(&trans->error_queue, skb);
    rxrpc_queue_work(&trans->error_handler);

    /* reset and regenerate socket error */
    spin_lock_bh(&sk->sk_error_queue.lock);
    sk->sk_err = 0;
    skb = skb_peek(&sk->sk_error_queue);
    if (skb) {
        sk->sk_err = SKB_EXT_ERR(skb)->ee.ee_errno;
        spin_unlock_bh(&sk->sk_error_queue.lock);
        sk->sk_error_report(sk);
    } else {
        spin_unlock_bh(&sk->sk_error_queue.lock);
    }

    _leave("");
}

/*
 * deal with UDP error messages
 */
void rxrpc_UDP_error_handler(struct work_struct *work)
{
    struct sock_extended_err *ee;
    struct sock_exterr_skb *serr;
    struct rxrpc_transport *trans =
        container_of(work, struct rxrpc_transport, error_handler);
    struct sk_buff *skb;
    int err;

    _enter("");

    skb = skb_dequeue(&trans->error_queue);
    if (!skb)
        return;

    serr = SKB_EXT_ERR(skb);
    ee = &serr->ee;

    _net("Rx Error o=%d t=%d c=%d e=%d",
         ee->ee_origin, ee->ee_type, ee->ee_code, ee->ee_errno);

    err = ee->ee_errno;

    switch (ee->ee_origin) {
    case SO_EE_ORIGIN_ICMP:
        switch (ee->ee_type) {
        case ICMP_DEST_UNREACH:
            switch (ee->ee_code) {
            case ICMP_NET_UNREACH:
                _net("Rx Received ICMP Network Unreachable");
                err = ENETUNREACH;
                break;
            case ICMP_HOST_UNREACH:
                _net("Rx Received ICMP Host Unreachable");
                err = EHOSTUNREACH;
                break;
            case ICMP_PORT_UNREACH:
                _net("Rx Received ICMP Port Unreachable");
                err = ECONNREFUSED;
                break;
            case ICMP_FRAG_NEEDED:
                _net("Rx Received ICMP Fragmentation Needed (%d)",
                     ee->ee_info);
                err = 0; /* dealt with elsewhere */
                break;
            case ICMP_NET_UNKNOWN:
                _net("Rx Received ICMP Unknown Network");
                err = ENETUNREACH;
                break;
            case ICMP_HOST_UNKNOWN:
                _net("Rx Received ICMP Unknown Host");
                err = EHOSTUNREACH;
                break;
            default:
                _net("Rx Received ICMP DestUnreach code=%u",
                     ee->ee_code);
                break;
            }
            break;

        case ICMP_TIME_EXCEEDED:
            _net("Rx Received ICMP TTL Exceeded");
            break;

        default:
            _proto("Rx Received ICMP error { type=%u code=%u }",
                   ee->ee_type, ee->ee_code);
            break;
        }
        break;

    case SO_EE_ORIGIN_LOCAL:
        _proto("Rx Received local error { error=%d }",
               ee->ee_errno);
        break;

    case SO_EE_ORIGIN_NONE:
    case SO_EE_ORIGIN_ICMP6:
    default:
        _proto("Rx Received error report { orig=%u }",
               ee->ee_origin);
        break;
    }

    /* terminate all the affected calls if there's an unrecoverable
     * error */
    if (err) {
        struct rxrpc_call *call, *_n;

        _debug("ISSUE ERROR %d", err);

        spin_lock_bh(&trans->peer->lock);
        trans->peer->net_error = err;

        list_for_each_entry_safe(call, _n, &trans->peer->error_targets,
                     error_link) {
            write_lock(&call->state_lock);
            if (call->state != RXRPC_CALL_COMPLETE &&
                call->state < RXRPC_CALL_NETWORK_ERROR) {
                call->state = RXRPC_CALL_NETWORK_ERROR;
                set_bit(RXRPC_CALL_RCVD_ERROR, &call->events);
                rxrpc_queue_call(call);
            }
            write_unlock(&call->state_lock);
            list_del_init(&call->error_link);
        }

        spin_unlock_bh(&trans->peer->lock);
    }

    if (!skb_queue_empty(&trans->error_queue))
        rxrpc_queue_work(&trans->error_handler);

    rxrpc_free_skb(skb);
    rxrpc_put_transport(trans);
    _leave("");
}