linux/net/rxrpc/ar-error.c
Willem de Bruijn 364a9e9324 sock: deduplicate errqueue dequeue
sk->sk_error_queue is dequeued in four locations. All share the
exact same logic. Deduplicate.

Also collapse the two critical sections for dequeue (at the top of
the recv handler) and signal (at the bottom).

This moves signal generation for the next packet forward, which should
be harmless.

It also changes the behavior if the recv handler exits early with an
error. Previously, a signal for follow-up packets on the errqueue
would then not be scheduled. The new behavior, to always signal, is
arguably a bug fix.

For rxrpc, the change causes the same function to be called repeatedly
for each queued packet (because the recv handler == sk_error_report).
It is likely that all packets will fail for the same reason (e.g.,
memory exhaustion).

This code runs without sk_lock held, so it is not safe to trust that
sk->sk_err is immutable inbetween releasing q->lock and the subsequent
test. Introduce int err just to avoid this potential race.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-01 21:49:08 -07:00

237 lines
5.4 KiB
C

/* Error message handling (ICMP)
*
* 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.
*/
#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 = sock_dequeue_err_skb(sk);
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 */
mtu = peer->if_mtu;
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);
_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("");
}