linux-kernel - [PATCH 4.17 127/324] rds: clean up loopback rds

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Message-Id: <20180823075002.256801890@linuxfoundation.org>
Date:   Thu, 23 Aug 2018 09:53:13 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Santosh Shilimkar <santosh.shilimkar@...cle.com>,
        Sowmini Varadhan <sowmini.varadhan@...cle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.17 127/324] rds: clean up loopback rds_connections on netns deletion

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sowmini Varadhan <sowmini.varadhan@...cle.com>

[ Upstream commit c809195f5523dd4d09403bbb1c9732d548aa0d1e ]

The RDS core module creates rds_connections based on callbacks
from rds_loop_transport when sending/receiving packets to local
addresses.

These connections will need to be cleaned up when they are
created from a netns that is not init_net, and that netns is deleted.

Add the changes aligned with the changes from
commit ebeeb1ad9b8a ("rds: tcp: use rds_destroy_pending() to synchronize
netns/module teardown and rds connection/workq management") for
rds_loop_transport

Reported-and-tested-by: syzbot+4c20b3866171ce8441d2@...kaller.appspotmail.com
Acked-by: Santosh Shilimkar <santosh.shilimkar@...cle.com>
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/rds/connection.c |   11 +++++++++-
 net/rds/loop.c       |   56 +++++++++++++++++++++++++++++++++++++++++++++++++++
 net/rds/loop.h       |    2 +
 3 files changed, 68 insertions(+), 1 deletion(-)

--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -659,11 +659,19 @@ static void rds_conn_info(struct socket
 
 int rds_conn_init(void)
 {
+	int ret;
+
+	ret = rds_loop_net_init(); /* register pernet callback */
+	if (ret)
+		return ret;
+
 	rds_conn_slab = kmem_cache_create("rds_connection",
 					  sizeof(struct rds_connection),
 					  0, 0, NULL);
-	if (!rds_conn_slab)
+	if (!rds_conn_slab) {
+		rds_loop_net_exit();
 		return -ENOMEM;
+	}
 
 	rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 	rds_info_register_func(RDS_INFO_SEND_MESSAGES,
@@ -676,6 +684,7 @@ int rds_conn_init(void)
 
 void rds_conn_exit(void)
 {
+	rds_loop_net_exit(); /* unregister pernet callback */
 	rds_loop_exit();
 
 	WARN_ON(!hlist_empty(rds_conn_hash));
--- a/net/rds/loop.c
+++ b/net/rds/loop.c
@@ -33,6 +33,8 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/in.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
 
 #include "rds_single_path.h"
 #include "rds.h"
@@ -40,6 +42,17 @@
 
 static DEFINE_SPINLOCK(loop_conns_lock);
 static LIST_HEAD(loop_conns);
+static atomic_t rds_loop_unloading = ATOMIC_INIT(0);
+
+static void rds_loop_set_unloading(void)
+{
+	atomic_set(&rds_loop_unloading, 1);
+}
+
+static bool rds_loop_is_unloading(struct rds_connection *conn)
+{
+	return atomic_read(&rds_loop_unloading) != 0;
+}
 
 /*
  * This 'loopback' transport is a special case for flows that originate
@@ -165,6 +178,8 @@ void rds_loop_exit(void)
 	struct rds_loop_connection *lc, *_lc;
 	LIST_HEAD(tmp_list);
 
+	rds_loop_set_unloading();
+	synchronize_rcu();
 	/* avoid calling conn_destroy with irqs off */
 	spin_lock_irq(&loop_conns_lock);
 	list_splice(&loop_conns, &tmp_list);
@@ -177,6 +192,46 @@ void rds_loop_exit(void)
 	}
 }
 
+static void rds_loop_kill_conns(struct net *net)
+{
+	struct rds_loop_connection *lc, *_lc;
+	LIST_HEAD(tmp_list);
+
+	spin_lock_irq(&loop_conns_lock);
+	list_for_each_entry_safe(lc, _lc, &loop_conns, loop_node)  {
+		struct net *c_net = read_pnet(&lc->conn->c_net);
+
+		if (net != c_net)
+			continue;
+		list_move_tail(&lc->loop_node, &tmp_list);
+	}
+	spin_unlock_irq(&loop_conns_lock);
+
+	list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
+		WARN_ON(lc->conn->c_passive);
+		rds_conn_destroy(lc->conn);
+	}
+}
+
+static void __net_exit rds_loop_exit_net(struct net *net)
+{
+	rds_loop_kill_conns(net);
+}
+
+static struct pernet_operations rds_loop_net_ops = {
+	.exit = rds_loop_exit_net,
+};
+
+int rds_loop_net_init(void)
+{
+	return register_pernet_device(&rds_loop_net_ops);
+}
+
+void rds_loop_net_exit(void)
+{
+	unregister_pernet_device(&rds_loop_net_ops);
+}
+
 /*
  * This is missing .xmit_* because loop doesn't go through generic
  * rds_send_xmit() and doesn't call rds_recv_incoming().  .listen_stop and
@@ -194,4 +249,5 @@ struct rds_transport rds_loop_transport
 	.inc_free		= rds_loop_inc_free,
 	.t_name			= "loopback",
 	.t_type			= RDS_TRANS_LOOP,
+	.t_unloading		= rds_loop_is_unloading,
 };
--- a/net/rds/loop.h
+++ b/net/rds/loop.h
@@ -5,6 +5,8 @@
 /* loop.c */
 extern struct rds_transport rds_loop_transport;
 
+int rds_loop_net_init(void);
+void rds_loop_net_exit(void);
 void rds_loop_exit(void);
 
 #endif