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Message-Id: <1516827819-133806-1-git-send-email-sowmini.varadhan@oracle.com>
Date: Wed, 24 Jan 2018 13:03:39 -0800
From: Sowmini Varadhan <sowmini.varadhan@...cle.com>
To: sowmini.varadhan@...cle.com
Cc: davem@...emloft.net, sowmini.varadhan@...cle.com,
santosh.shilimkar@...cle.com
Subject: [PATCH net-next] rds: tcp: per-netns flag to stop new connection creation when rds-tcp is being dismantled
An rds_connection can get added during netns deletion between lines 528
and 529 of
506 static void rds_tcp_kill_sock(struct net *net)
:
/* code to pull out all the rds_connections that should be destroyed */
:
528 spin_unlock_irq(&rds_tcp_conn_lock);
529 list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
530 rds_conn_destroy(tc->t_cpath->cp_conn);
Such an rds_connection would miss out the rds_conn_destroy()
loop (that cancels all pending work) and (if it was scheduled
after netns deletion) could trigger the use-after-free.
A similar race-window exists for the module unload path
in rds_tcp_exit -> rds_tcp_destroy_conns
To avoid the addition of new rds_connections during kill_sock
or netns_delete, this patch introduces a per-netns flag,
RTN_DELETE_PENDING, that will cause RDS connection creation to fail.
RCU is used to make sure that we wait for the critical
section of __rds_conn_create threads (that may have started before
the setting of RTN_DELETE_PENDING) to complete before starting
the connection destruction.
Reported-by: syzbot+bbd8e9a06452cc48059b@...kaller.appspotmail.com
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
---
net/rds/connection.c | 3 ++
net/rds/tcp.c | 82 ++++++++++++++++++++++++++++++++-----------------
net/rds/tcp.h | 1 +
3 files changed, 57 insertions(+), 29 deletions(-)
diff --git a/net/rds/connection.c b/net/rds/connection.c
index b10c0ef..2ae539d 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -220,8 +220,10 @@ static void __rds_conn_path_init(struct rds_connection *conn,
is_outgoing);
conn->c_path[i].cp_index = i;
}
+ rcu_read_lock();
ret = trans->conn_alloc(conn, gfp);
if (ret) {
+ rcu_read_unlock();
kfree(conn->c_path);
kmem_cache_free(rds_conn_slab, conn);
conn = ERR_PTR(ret);
@@ -283,6 +285,7 @@ static void __rds_conn_path_init(struct rds_connection *conn,
}
}
spin_unlock_irqrestore(&rds_conn_lock, flags);
+ rcu_read_unlock();
out:
return conn;
diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index 9920d2f..2bdd3cc 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -274,14 +274,13 @@ static int rds_tcp_laddr_check(struct net *net, __be32 addr)
static void rds_tcp_conn_free(void *arg)
{
struct rds_tcp_connection *tc = arg;
- unsigned long flags;
rdsdebug("freeing tc %p\n", tc);
- spin_lock_irqsave(&rds_tcp_conn_lock, flags);
+ spin_lock_bh(&rds_tcp_conn_lock);
if (!tc->t_tcp_node_detached)
list_del(&tc->t_tcp_node);
- spin_unlock_irqrestore(&rds_tcp_conn_lock, flags);
+ spin_unlock_bh(&rds_tcp_conn_lock);
kmem_cache_free(rds_tcp_conn_slab, tc);
}
@@ -296,7 +295,7 @@ static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)
tc = kmem_cache_alloc(rds_tcp_conn_slab, gfp);
if (!tc) {
ret = -ENOMEM;
- break;
+ goto fail;
}
mutex_init(&tc->t_conn_path_lock);
tc->t_sock = NULL;
@@ -306,14 +305,25 @@ static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)
conn->c_path[i].cp_transport_data = tc;
tc->t_cpath = &conn->c_path[i];
+ tc->t_tcp_node_detached = true;
- spin_lock_irq(&rds_tcp_conn_lock);
- tc->t_tcp_node_detached = false;
- list_add_tail(&tc->t_tcp_node, &rds_tcp_conn_list);
- spin_unlock_irq(&rds_tcp_conn_lock);
rdsdebug("rds_conn_path [%d] tc %p\n", i,
conn->c_path[i].cp_transport_data);
}
+ spin_lock_bh(&rds_tcp_conn_lock);
+ if (rds_tcp_netns_delete_pending(rds_conn_net(conn))) {
+ rdsdebug("RTN_DELETE_PENDING\n");
+ ret = -ENETDOWN;
+ spin_unlock_bh(&rds_tcp_conn_lock);
+ goto fail;
+ }
+ for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+ tc = conn->c_path[i].cp_transport_data;
+ tc->t_tcp_node_detached = false;
+ list_add_tail(&tc->t_tcp_node, &rds_tcp_conn_list);
+ }
+ spin_unlock_bh(&rds_tcp_conn_lock);
+fail:
if (ret) {
for (j = 0; j < i; j++)
rds_tcp_conn_free(conn->c_path[j].cp_transport_data);
@@ -332,23 +342,6 @@ static bool list_has_conn(struct list_head *list, struct rds_connection *conn)
return false;
}
-static void rds_tcp_destroy_conns(void)
-{
- struct rds_tcp_connection *tc, *_tc;
- LIST_HEAD(tmp_list);
-
- /* avoid calling conn_destroy with irqs off */
- spin_lock_irq(&rds_tcp_conn_lock);
- list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
- if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
- list_move_tail(&tc->t_tcp_node, &tmp_list);
- }
- spin_unlock_irq(&rds_tcp_conn_lock);
-
- list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
- rds_conn_destroy(tc->t_cpath->cp_conn);
-}
-
static void rds_tcp_exit(void);
struct rds_transport rds_tcp_transport = {
@@ -382,8 +375,30 @@ struct rds_tcp_net {
struct ctl_table *ctl_table;
int sndbuf_size;
int rcvbuf_size;
+ unsigned long rtn_flags;
+#define RTN_DELETE_PENDING 0
};
+static void rds_tcp_destroy_conns(void)
+{
+ struct rds_tcp_connection *tc, *_tc;
+ struct rds_tcp_net *rtn = net_generic(&init_net, rds_tcp_netid);
+ LIST_HEAD(tmp_list);
+
+ /* avoid calling conn_destroy with irqs off */
+ set_bit(RTN_DELETE_PENDING, &rtn->rtn_flags);
+ synchronize_rcu();
+ spin_lock_bh(&rds_tcp_conn_lock);
+ list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
+ if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
+ list_move_tail(&tc->t_tcp_node, &tmp_list);
+ }
+ spin_unlock_bh(&rds_tcp_conn_lock);
+
+ list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
+ rds_conn_destroy(tc->t_cpath->cp_conn);
+}
+
/* All module specific customizations to the RDS-TCP socket should be done in
* rds_tcp_tune() and applied after socket creation.
*/
@@ -504,6 +519,13 @@ static void __net_exit rds_tcp_exit_net(struct net *net)
.size = sizeof(struct rds_tcp_net),
};
+bool rds_tcp_netns_delete_pending(struct net *net)
+{
+ struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+
+ return test_bit(RTN_DELETE_PENDING, &rtn->rtn_flags);
+}
+
static void rds_tcp_kill_sock(struct net *net)
{
struct rds_tcp_connection *tc, *_tc;
@@ -513,7 +535,9 @@ static void rds_tcp_kill_sock(struct net *net)
rtn->rds_tcp_listen_sock = NULL;
rds_tcp_listen_stop(lsock, &rtn->rds_tcp_accept_w);
- spin_lock_irq(&rds_tcp_conn_lock);
+ set_bit(RTN_DELETE_PENDING, &rtn->rtn_flags);
+ synchronize_rcu();
+ spin_lock_bh(&rds_tcp_conn_lock);
list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
@@ -526,7 +550,7 @@ static void rds_tcp_kill_sock(struct net *net)
tc->t_tcp_node_detached = true;
}
}
- spin_unlock_irq(&rds_tcp_conn_lock);
+ spin_unlock_bh(&rds_tcp_conn_lock);
list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
rds_conn_destroy(tc->t_cpath->cp_conn);
}
@@ -574,7 +598,7 @@ static void rds_tcp_sysctl_reset(struct net *net)
{
struct rds_tcp_connection *tc, *_tc;
- spin_lock_irq(&rds_tcp_conn_lock);
+ spin_lock_bh(&rds_tcp_conn_lock);
list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
@@ -584,7 +608,7 @@ static void rds_tcp_sysctl_reset(struct net *net)
/* reconnect with new parameters */
rds_conn_path_drop(tc->t_cpath, false);
}
- spin_unlock_irq(&rds_tcp_conn_lock);
+ spin_unlock_bh(&rds_tcp_conn_lock);
}
static int rds_tcp_skbuf_handler(struct ctl_table *ctl, int write,
diff --git a/net/rds/tcp.h b/net/rds/tcp.h
index c6fa080..b07dbd7 100644
--- a/net/rds/tcp.h
+++ b/net/rds/tcp.h
@@ -60,6 +60,7 @@ void rds_tcp_restore_callbacks(struct socket *sock,
u64 rds_tcp_map_seq(struct rds_tcp_connection *tc, u32 seq);
extern struct rds_transport rds_tcp_transport;
void rds_tcp_accept_work(struct sock *sk);
+bool rds_tcp_netns_delete_pending(struct net *net);
/* tcp_connect.c */
int rds_tcp_conn_path_connect(struct rds_conn_path *cp);
--
1.7.1
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