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There's a locking issue with the per-netns list of calls in rxrpc. The
pieces of code that add and remove a call from the list use write_lock()
and the calls procfile uses read_lock() to access it. However, the timer
callback function may trigger a removal by trying to queue a call for
processing and finding that it's already queued - at which point it has a
spare refcount that it has to do something with. Unfortunately, if it puts
the call and this reduces the refcount to 0, the call will be removed from
the list. Unfortunately, since the _bh variants of the locking functions
aren't used, this can deadlock.
================================
WARNING: inconsistent lock state
5.18.0-rc3-build4+ #10 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/2/25 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff888107ac4038 (&rxnet->call_lock){+.?.}-{2:2}, at: rxrpc_put_call+0x103/0x14b
{SOFTIRQ-ON-W} state was registered at:
...
Possible unsafe locking scenario:
CPU0
----
lock(&rxnet->call_lock);
<Interrupt>
lock(&rxnet->call_lock);
*** DEADLOCK ***
1 lock held by ksoftirqd/2/25:
#0: ffff8881008ffdb0 ((&call->timer)){+.-.}-{0:0}, at: call_timer_fn+0x5/0x23d
Changes
=======
ver #2)
- Changed to using list_next_rcu() rather than rcu_dereference() directly.
Fixes: 17926a7932 ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: David S. Miller <davem@davemloft.net>
136 lines
3.8 KiB
C
136 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* rxrpc network namespace handling.
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*
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* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/proc_fs.h>
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#include "ar-internal.h"
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unsigned int rxrpc_net_id;
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static void rxrpc_client_conn_reap_timeout(struct timer_list *timer)
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{
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struct rxrpc_net *rxnet =
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container_of(timer, struct rxrpc_net, client_conn_reap_timer);
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if (rxnet->live)
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rxrpc_queue_work(&rxnet->client_conn_reaper);
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}
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static void rxrpc_service_conn_reap_timeout(struct timer_list *timer)
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{
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struct rxrpc_net *rxnet =
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container_of(timer, struct rxrpc_net, service_conn_reap_timer);
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if (rxnet->live)
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rxrpc_queue_work(&rxnet->service_conn_reaper);
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}
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static void rxrpc_peer_keepalive_timeout(struct timer_list *timer)
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{
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struct rxrpc_net *rxnet =
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container_of(timer, struct rxrpc_net, peer_keepalive_timer);
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if (rxnet->live)
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rxrpc_queue_work(&rxnet->peer_keepalive_work);
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}
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/*
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* Initialise a per-network namespace record.
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*/
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static __net_init int rxrpc_init_net(struct net *net)
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{
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struct rxrpc_net *rxnet = rxrpc_net(net);
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int ret, i;
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rxnet->live = true;
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get_random_bytes(&rxnet->epoch, sizeof(rxnet->epoch));
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rxnet->epoch |= RXRPC_RANDOM_EPOCH;
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INIT_LIST_HEAD(&rxnet->calls);
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spin_lock_init(&rxnet->call_lock);
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atomic_set(&rxnet->nr_calls, 1);
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atomic_set(&rxnet->nr_conns, 1);
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INIT_LIST_HEAD(&rxnet->conn_proc_list);
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INIT_LIST_HEAD(&rxnet->service_conns);
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rwlock_init(&rxnet->conn_lock);
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INIT_WORK(&rxnet->service_conn_reaper,
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rxrpc_service_connection_reaper);
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timer_setup(&rxnet->service_conn_reap_timer,
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rxrpc_service_conn_reap_timeout, 0);
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atomic_set(&rxnet->nr_client_conns, 0);
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rxnet->kill_all_client_conns = false;
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spin_lock_init(&rxnet->client_conn_cache_lock);
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spin_lock_init(&rxnet->client_conn_discard_lock);
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INIT_LIST_HEAD(&rxnet->idle_client_conns);
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INIT_WORK(&rxnet->client_conn_reaper,
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rxrpc_discard_expired_client_conns);
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timer_setup(&rxnet->client_conn_reap_timer,
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rxrpc_client_conn_reap_timeout, 0);
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INIT_HLIST_HEAD(&rxnet->local_endpoints);
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mutex_init(&rxnet->local_mutex);
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hash_init(rxnet->peer_hash);
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spin_lock_init(&rxnet->peer_hash_lock);
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for (i = 0; i < ARRAY_SIZE(rxnet->peer_keepalive); i++)
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INIT_LIST_HEAD(&rxnet->peer_keepalive[i]);
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INIT_LIST_HEAD(&rxnet->peer_keepalive_new);
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timer_setup(&rxnet->peer_keepalive_timer,
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rxrpc_peer_keepalive_timeout, 0);
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INIT_WORK(&rxnet->peer_keepalive_work, rxrpc_peer_keepalive_worker);
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rxnet->peer_keepalive_base = ktime_get_seconds();
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ret = -ENOMEM;
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rxnet->proc_net = proc_net_mkdir(net, "rxrpc", net->proc_net);
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if (!rxnet->proc_net)
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goto err_proc;
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proc_create_net("calls", 0444, rxnet->proc_net, &rxrpc_call_seq_ops,
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sizeof(struct seq_net_private));
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proc_create_net("conns", 0444, rxnet->proc_net,
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&rxrpc_connection_seq_ops,
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sizeof(struct seq_net_private));
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proc_create_net("peers", 0444, rxnet->proc_net,
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&rxrpc_peer_seq_ops,
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sizeof(struct seq_net_private));
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proc_create_net("locals", 0444, rxnet->proc_net,
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&rxrpc_local_seq_ops,
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sizeof(struct seq_net_private));
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return 0;
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err_proc:
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rxnet->live = false;
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return ret;
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}
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/*
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* Clean up a per-network namespace record.
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*/
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static __net_exit void rxrpc_exit_net(struct net *net)
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{
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struct rxrpc_net *rxnet = rxrpc_net(net);
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rxnet->live = false;
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del_timer_sync(&rxnet->peer_keepalive_timer);
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cancel_work_sync(&rxnet->peer_keepalive_work);
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/* Remove the timer again as the worker may have restarted it. */
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del_timer_sync(&rxnet->peer_keepalive_timer);
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rxrpc_destroy_all_calls(rxnet);
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rxrpc_destroy_all_connections(rxnet);
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rxrpc_destroy_all_peers(rxnet);
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rxrpc_destroy_all_locals(rxnet);
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proc_remove(rxnet->proc_net);
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}
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struct pernet_operations rxrpc_net_ops = {
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.init = rxrpc_init_net,
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.exit = rxrpc_exit_net,
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.id = &rxrpc_net_id,
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.size = sizeof(struct rxrpc_net),
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};
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