linux/net/rxrpc/local_object.c
David Howells 1e9e5c9521 rxrpc: Reduce the rxrpc_local::services list to a pointer
Reduce the rxrpc_local::services list to just a pointer as we don't permit
multiple service endpoints to bind to a single transport endpoints (this is
excluded by rxrpc_lookup_local()).

The reason we don't allow this is that if you send a request to an AFS
filesystem service, it will try to talk back to your cache manager on the
port you sent from (this is how file change notifications are handled).  To
prevent someone from stealing your CM callbacks, we don't let AF_RXRPC
sockets share a UDP socket if at least one of them has a service bound.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-29 22:57:47 +01:00

380 lines
9.2 KiB
C

/* Local endpoint object management
*
* Copyright (C) 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 Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, 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/slab.h>
#include <linux/udp.h>
#include <linux/ip.h>
#include <linux/hashtable.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"
static void rxrpc_local_processor(struct work_struct *);
static void rxrpc_local_rcu(struct rcu_head *);
static DEFINE_MUTEX(rxrpc_local_mutex);
static LIST_HEAD(rxrpc_local_endpoints);
/*
* Compare a local to an address. Return -ve, 0 or +ve to indicate less than,
* same or greater than.
*
* We explicitly don't compare the RxRPC service ID as we want to reject
* conflicting uses by differing services. Further, we don't want to share
* addresses with different options (IPv6), so we don't compare those bits
* either.
*/
static long rxrpc_local_cmp_key(const struct rxrpc_local *local,
const struct sockaddr_rxrpc *srx)
{
long diff;
diff = ((local->srx.transport_type - srx->transport_type) ?:
(local->srx.transport_len - srx->transport_len) ?:
(local->srx.transport.family - srx->transport.family));
if (diff != 0)
return diff;
switch (srx->transport.family) {
case AF_INET:
/* If the choice of UDP port is left up to the transport, then
* the endpoint record doesn't match.
*/
return ((u16 __force)local->srx.transport.sin.sin_port -
(u16 __force)srx->transport.sin.sin_port) ?:
memcmp(&local->srx.transport.sin.sin_addr,
&srx->transport.sin.sin_addr,
sizeof(struct in_addr));
#ifdef CONFIG_AF_RXRPC_IPV6
case AF_INET6:
/* If the choice of UDP6 port is left up to the transport, then
* the endpoint record doesn't match.
*/
return ((u16 __force)local->srx.transport.sin6.sin6_port -
(u16 __force)srx->transport.sin6.sin6_port) ?:
memcmp(&local->srx.transport.sin6.sin6_addr,
&srx->transport.sin6.sin6_addr,
sizeof(struct in6_addr));
#endif
default:
BUG();
}
}
/*
* Allocate a new local endpoint.
*/
static struct rxrpc_local *rxrpc_alloc_local(const struct sockaddr_rxrpc *srx)
{
struct rxrpc_local *local;
local = kzalloc(sizeof(struct rxrpc_local), GFP_KERNEL);
if (local) {
atomic_set(&local->usage, 1);
INIT_LIST_HEAD(&local->link);
INIT_WORK(&local->processor, rxrpc_local_processor);
init_rwsem(&local->defrag_sem);
skb_queue_head_init(&local->reject_queue);
skb_queue_head_init(&local->event_queue);
local->client_conns = RB_ROOT;
spin_lock_init(&local->client_conns_lock);
spin_lock_init(&local->lock);
rwlock_init(&local->services_lock);
local->debug_id = atomic_inc_return(&rxrpc_debug_id);
memcpy(&local->srx, srx, sizeof(*srx));
}
_leave(" = %p", local);
return local;
}
/*
* create the local socket
* - must be called with rxrpc_local_mutex locked
*/
static int rxrpc_open_socket(struct rxrpc_local *local)
{
struct sock *sock;
int ret, opt;
_enter("%p{%d,%d}",
local, local->srx.transport_type, local->srx.transport.family);
/* create a socket to represent the local endpoint */
ret = sock_create_kern(&init_net, local->srx.transport.family,
local->srx.transport_type, 0, &local->socket);
if (ret < 0) {
_leave(" = %d [socket]", ret);
return ret;
}
/* if a local address was supplied then bind it */
if (local->srx.transport_len > sizeof(sa_family_t)) {
_debug("bind");
ret = kernel_bind(local->socket,
(struct sockaddr *)&local->srx.transport,
local->srx.transport_len);
if (ret < 0) {
_debug("bind failed %d", ret);
goto error;
}
}
/* we want to receive ICMP errors */
opt = 1;
ret = kernel_setsockopt(local->socket, SOL_IP, IP_RECVERR,
(char *) &opt, sizeof(opt));
if (ret < 0) {
_debug("setsockopt failed");
goto error;
}
/* we want to set the don't fragment bit */
opt = IP_PMTUDISC_DO;
ret = kernel_setsockopt(local->socket, SOL_IP, IP_MTU_DISCOVER,
(char *) &opt, sizeof(opt));
if (ret < 0) {
_debug("setsockopt failed");
goto error;
}
/* set the socket up */
sock = local->socket->sk;
sock->sk_user_data = local;
sock->sk_data_ready = rxrpc_data_ready;
sock->sk_error_report = rxrpc_error_report;
_leave(" = 0");
return 0;
error:
kernel_sock_shutdown(local->socket, SHUT_RDWR);
local->socket->sk->sk_user_data = NULL;
sock_release(local->socket);
local->socket = NULL;
_leave(" = %d", ret);
return ret;
}
/*
* Look up or create a new local endpoint using the specified local address.
*/
struct rxrpc_local *rxrpc_lookup_local(const struct sockaddr_rxrpc *srx)
{
struct rxrpc_local *local;
struct list_head *cursor;
const char *age;
long diff;
int ret;
_enter("{%d,%d,%pISp}",
srx->transport_type, srx->transport.family, &srx->transport);
mutex_lock(&rxrpc_local_mutex);
for (cursor = rxrpc_local_endpoints.next;
cursor != &rxrpc_local_endpoints;
cursor = cursor->next) {
local = list_entry(cursor, struct rxrpc_local, link);
diff = rxrpc_local_cmp_key(local, srx);
if (diff < 0)
continue;
if (diff > 0)
break;
/* Services aren't allowed to share transport sockets, so
* reject that here. It is possible that the object is dying -
* but it may also still have the local transport address that
* we want bound.
*/
if (srx->srx_service) {
local = NULL;
goto addr_in_use;
}
/* Found a match. We replace a dying object. Attempting to
* bind the transport socket may still fail if we're attempting
* to use a local address that the dying object is still using.
*/
if (!rxrpc_get_local_maybe(local)) {
cursor = cursor->next;
list_del_init(&local->link);
break;
}
age = "old";
goto found;
}
local = rxrpc_alloc_local(srx);
if (!local)
goto nomem;
ret = rxrpc_open_socket(local);
if (ret < 0)
goto sock_error;
list_add_tail(&local->link, cursor);
age = "new";
found:
mutex_unlock(&rxrpc_local_mutex);
_net("LOCAL %s %d {%pISp}",
age, local->debug_id, &local->srx.transport);
_leave(" = %p", local);
return local;
nomem:
ret = -ENOMEM;
sock_error:
mutex_unlock(&rxrpc_local_mutex);
kfree(local);
_leave(" = %d", ret);
return ERR_PTR(ret);
addr_in_use:
mutex_unlock(&rxrpc_local_mutex);
_leave(" = -EADDRINUSE");
return ERR_PTR(-EADDRINUSE);
}
/*
* A local endpoint reached its end of life.
*/
void __rxrpc_put_local(struct rxrpc_local *local)
{
_enter("%d", local->debug_id);
rxrpc_queue_work(&local->processor);
}
/*
* Destroy a local endpoint's socket and then hand the record to RCU to dispose
* of.
*
* Closing the socket cannot be done from bottom half context or RCU callback
* context because it might sleep.
*/
static void rxrpc_local_destroyer(struct rxrpc_local *local)
{
struct socket *socket = local->socket;
_enter("%d", local->debug_id);
/* We can get a race between an incoming call packet queueing the
* processor again and the work processor starting the destruction
* process which will shut down the UDP socket.
*/
if (local->dead) {
_leave(" [already dead]");
return;
}
local->dead = true;
mutex_lock(&rxrpc_local_mutex);
list_del_init(&local->link);
mutex_unlock(&rxrpc_local_mutex);
ASSERT(RB_EMPTY_ROOT(&local->client_conns));
ASSERT(!local->service);
if (socket) {
local->socket = NULL;
kernel_sock_shutdown(socket, SHUT_RDWR);
socket->sk->sk_user_data = NULL;
sock_release(socket);
}
/* At this point, there should be no more packets coming in to the
* local endpoint.
*/
rxrpc_purge_queue(&local->reject_queue);
rxrpc_purge_queue(&local->event_queue);
_debug("rcu local %d", local->debug_id);
call_rcu(&local->rcu, rxrpc_local_rcu);
}
/*
* Process events on an endpoint
*/
static void rxrpc_local_processor(struct work_struct *work)
{
struct rxrpc_local *local =
container_of(work, struct rxrpc_local, processor);
bool again;
_enter("%d", local->debug_id);
do {
again = false;
if (atomic_read(&local->usage) == 0)
return rxrpc_local_destroyer(local);
if (!skb_queue_empty(&local->reject_queue)) {
rxrpc_reject_packets(local);
again = true;
}
if (!skb_queue_empty(&local->event_queue)) {
rxrpc_process_local_events(local);
again = true;
}
} while (again);
}
/*
* Destroy a local endpoint after the RCU grace period expires.
*/
static void rxrpc_local_rcu(struct rcu_head *rcu)
{
struct rxrpc_local *local = container_of(rcu, struct rxrpc_local, rcu);
_enter("%d", local->debug_id);
ASSERT(!work_pending(&local->processor));
_net("DESTROY LOCAL %d", local->debug_id);
kfree(local);
_leave("");
}
/*
* Verify the local endpoint list is empty by this point.
*/
void __exit rxrpc_destroy_all_locals(void)
{
struct rxrpc_local *local;
_enter("");
flush_workqueue(rxrpc_workqueue);
if (!list_empty(&rxrpc_local_endpoints)) {
mutex_lock(&rxrpc_local_mutex);
list_for_each_entry(local, &rxrpc_local_endpoints, link) {
pr_err("AF_RXRPC: Leaked local %p {%d}\n",
local, atomic_read(&local->usage));
}
mutex_unlock(&rxrpc_local_mutex);
BUG();
}
rcu_barrier();
}