linux/net/rxrpc/peer_object.c
David Howells f66d749019 rxrpc: Use the peer record to distribute network errors
Use the peer record to distribute network errors rather than the transport
object (which I want to get rid of).  An error from a particular peer
terminates all calls on that peer.

For future consideration:

 (1) For ICMP-induced errors it might be worth trying to extract the RxRPC
     header from the offending packet, if one is returned attached to the
     ICMP packet, to better direct the error.

     This may be overkill, though, since an ICMP packet would be expected
     to be relating to the destination port, machine or network.  RxRPC
     ABORT and BUSY packets give notice at RxRPC level.

 (2) To also abort connection-level communications (such as CHALLENGE
     packets) where indicted by an error - but that requires some revamping
     of the connection event handling first.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-06-15 10:15:16 +01:00

311 lines
7.4 KiB
C

/* RxRPC remote transport endpoint record management
*
* Copyright (C) 2007, 2016 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/udp.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <linux/hashtable.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <net/ip.h>
#include <net/route.h>
#include "ar-internal.h"
static DEFINE_HASHTABLE(rxrpc_peer_hash, 10);
static DEFINE_SPINLOCK(rxrpc_peer_hash_lock);
/*
* Hash a peer key.
*/
static unsigned long rxrpc_peer_hash_key(struct rxrpc_local *local,
const struct sockaddr_rxrpc *srx)
{
const u16 *p;
unsigned int i, size;
unsigned long hash_key;
_enter("");
hash_key = (unsigned long)local / __alignof__(*local);
hash_key += srx->transport_type;
hash_key += srx->transport_len;
hash_key += srx->transport.family;
switch (srx->transport.family) {
case AF_INET:
hash_key += (u16 __force)srx->transport.sin.sin_port;
size = sizeof(srx->transport.sin.sin_addr);
p = (u16 *)&srx->transport.sin.sin_addr;
break;
}
/* Step through the peer address in 16-bit portions for speed */
for (i = 0; i < size; i += sizeof(*p), p++)
hash_key += *p;
_leave(" 0x%lx", hash_key);
return hash_key;
}
/*
* Compare a peer to a key. Return -ve, 0 or +ve to indicate less than, same
* or greater than.
*
* Unfortunately, the primitives in linux/hashtable.h don't allow for sorted
* buckets and mid-bucket insertion, so we don't make full use of this
* information at this point.
*/
static long rxrpc_peer_cmp_key(const struct rxrpc_peer *peer,
struct rxrpc_local *local,
const struct sockaddr_rxrpc *srx,
unsigned long hash_key)
{
long diff;
diff = ((peer->hash_key - hash_key) ?:
((unsigned long)peer->local - (unsigned long)local) ?:
(peer->srx.transport_type - srx->transport_type) ?:
(peer->srx.transport_len - srx->transport_len) ?:
(peer->srx.transport.family - srx->transport.family));
if (diff != 0)
return diff;
switch (srx->transport.family) {
case AF_INET:
return ((u16 __force)peer->srx.transport.sin.sin_port -
(u16 __force)srx->transport.sin.sin_port) ?:
memcmp(&peer->srx.transport.sin.sin_addr,
&srx->transport.sin.sin_addr,
sizeof(struct in_addr));
default:
BUG();
}
}
/*
* Look up a remote transport endpoint for the specified address using RCU.
*/
static struct rxrpc_peer *__rxrpc_lookup_peer_rcu(
struct rxrpc_local *local,
const struct sockaddr_rxrpc *srx,
unsigned long hash_key)
{
struct rxrpc_peer *peer;
hash_for_each_possible_rcu(rxrpc_peer_hash, peer, hash_link, hash_key) {
if (rxrpc_peer_cmp_key(peer, local, srx, hash_key) == 0) {
if (atomic_read(&peer->usage) == 0)
return NULL;
return peer;
}
}
return NULL;
}
/*
* Look up a remote transport endpoint for the specified address using RCU.
*/
struct rxrpc_peer *rxrpc_lookup_peer_rcu(struct rxrpc_local *local,
const struct sockaddr_rxrpc *srx)
{
struct rxrpc_peer *peer;
unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
if (peer) {
switch (srx->transport.family) {
case AF_INET:
_net("PEER %d {%d,%u,%pI4+%hu}",
peer->debug_id,
peer->srx.transport_type,
peer->srx.transport.family,
&peer->srx.transport.sin.sin_addr,
ntohs(peer->srx.transport.sin.sin_port));
break;
}
_leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
}
return peer;
}
/*
* assess the MTU size for the network interface through which this peer is
* reached
*/
static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
{
struct rtable *rt;
struct flowi4 fl4;
peer->if_mtu = 1500;
rt = ip_route_output_ports(&init_net, &fl4, NULL,
peer->srx.transport.sin.sin_addr.s_addr, 0,
htons(7000), htons(7001),
IPPROTO_UDP, 0, 0);
if (IS_ERR(rt)) {
_leave(" [route err %ld]", PTR_ERR(rt));
return;
}
peer->if_mtu = dst_mtu(&rt->dst);
dst_release(&rt->dst);
_leave(" [if_mtu %u]", peer->if_mtu);
}
/*
* Allocate a peer.
*/
struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp)
{
struct rxrpc_peer *peer;
_enter("");
peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
if (peer) {
atomic_set(&peer->usage, 1);
peer->local = local;
INIT_HLIST_HEAD(&peer->error_targets);
INIT_WORK(&peer->error_distributor,
&rxrpc_peer_error_distributor);
spin_lock_init(&peer->lock);
peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
}
_leave(" = %p", peer);
return peer;
}
/*
* Set up a new peer.
*/
static struct rxrpc_peer *rxrpc_create_peer(struct rxrpc_local *local,
struct sockaddr_rxrpc *srx,
unsigned long hash_key,
gfp_t gfp)
{
struct rxrpc_peer *peer;
_enter("");
peer = rxrpc_alloc_peer(local, gfp);
if (peer) {
peer->hash_key = hash_key;
memcpy(&peer->srx, srx, sizeof(*srx));
rxrpc_assess_MTU_size(peer);
peer->mtu = peer->if_mtu;
if (srx->transport.family == AF_INET) {
peer->hdrsize = sizeof(struct iphdr);
switch (srx->transport_type) {
case SOCK_DGRAM:
peer->hdrsize += sizeof(struct udphdr);
break;
default:
BUG();
break;
}
} else {
BUG();
}
peer->hdrsize += sizeof(struct rxrpc_wire_header);
peer->maxdata = peer->mtu - peer->hdrsize;
}
_leave(" = %p", peer);
return peer;
}
/*
* obtain a remote transport endpoint for the specified address
*/
struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *local,
struct sockaddr_rxrpc *srx, gfp_t gfp)
{
struct rxrpc_peer *peer, *candidate;
unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
_enter("{%d,%d,%pI4+%hu}",
srx->transport_type,
srx->transport_len,
&srx->transport.sin.sin_addr,
ntohs(srx->transport.sin.sin_port));
/* search the peer list first */
rcu_read_lock();
peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
if (peer && !rxrpc_get_peer_maybe(peer))
peer = NULL;
rcu_read_unlock();
if (!peer) {
/* The peer is not yet present in hash - create a candidate
* for a new record and then redo the search.
*/
candidate = rxrpc_create_peer(local, srx, hash_key, gfp);
if (!candidate) {
_leave(" = NULL [nomem]");
return NULL;
}
spin_lock(&rxrpc_peer_hash_lock);
/* Need to check that we aren't racing with someone else */
peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
if (peer && !rxrpc_get_peer_maybe(peer))
peer = NULL;
if (!peer)
hash_add_rcu(rxrpc_peer_hash,
&candidate->hash_link, hash_key);
spin_unlock(&rxrpc_peer_hash_lock);
if (peer)
kfree(candidate);
else
peer = candidate;
}
_net("PEER %d {%d,%pI4+%hu}",
peer->debug_id,
peer->srx.transport_type,
&peer->srx.transport.sin.sin_addr,
ntohs(peer->srx.transport.sin.sin_port));
_leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
return peer;
}
/*
* Discard a ref on a remote peer record.
*/
void __rxrpc_put_peer(struct rxrpc_peer *peer)
{
ASSERT(hlist_empty(&peer->error_targets));
spin_lock(&rxrpc_peer_hash_lock);
hash_del_rcu(&peer->hash_link);
spin_unlock(&rxrpc_peer_hash_lock);
kfree_rcu(peer, rcu);
}