From: Tuong Lien tuong.t.lien@dektech.com.au
[ Upstream commit 49afb806cb650dd1f06f191994f3aa657d264009 ]
When a socket is suddenly shutdown or released, it will reject all the unreceived messages in its receive queue. This applies to a connected socket too, whereas there is only one 'FIN' message required to be sent back to its peer in this case.
In case there are many messages in the queue and/or some connections with such messages are shutdown at the same time, the link layer will easily get overflowed at the 'TIPC_SYSTEM_IMPORTANCE' backlog level because of the message rejections. As a result, the link will be taken down. Moreover, immediately when the link is re-established, the socket layer can continue to reject the messages and the same issue happens...
The commit refactors the '__tipc_shutdown()' function to only send one 'FIN' in the situation mentioned above. For the connectionless case, it is unavoidable but usually there is no rejections for such socket messages because they are 'dest-droppable' by default.
In addition, the new code makes the other socket states clear (e.g.'TIPC_LISTEN') and treats as a separate case to avoid misbehaving.
Acked-by: Ying Xue ying.xue@windriver.com Acked-by: Jon Maloy jon.maloy@ericsson.com Signed-off-by: Tuong Lien tuong.t.lien@dektech.com.au Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/tipc/socket.c | 53 ++++++++++++++++++++++++++++------------------- 1 file changed, 32 insertions(+), 21 deletions(-)
diff --git a/net/tipc/socket.c b/net/tipc/socket.c index 5318bb6611abc..592c6b19aca72 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -260,12 +260,12 @@ static void tipc_sk_respond(struct sock *sk, struct sk_buff *skb, int err) * * Caller must hold socket lock */ -static void tsk_rej_rx_queue(struct sock *sk) +static void tsk_rej_rx_queue(struct sock *sk, int error) { struct sk_buff *skb;
while ((skb = __skb_dequeue(&sk->sk_receive_queue))) - tipc_sk_respond(sk, skb, TIPC_ERR_NO_PORT); + tipc_sk_respond(sk, skb, error); }
static bool tipc_sk_connected(struct sock *sk) @@ -515,34 +515,45 @@ static void __tipc_shutdown(struct socket *sock, int error) /* Remove any pending SYN message */ __skb_queue_purge(&sk->sk_write_queue);
- /* Reject all unreceived messages, except on an active connection - * (which disconnects locally & sends a 'FIN+' to peer). - */ - while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) { - if (TIPC_SKB_CB(skb)->bytes_read) { - kfree_skb(skb); - continue; - } - if (!tipc_sk_type_connectionless(sk) && - sk->sk_state != TIPC_DISCONNECTING) { - tipc_set_sk_state(sk, TIPC_DISCONNECTING); - tipc_node_remove_conn(net, dnode, tsk->portid); - } - tipc_sk_respond(sk, skb, error); + /* Remove partially received buffer if any */ + skb = skb_peek(&sk->sk_receive_queue); + if (skb && TIPC_SKB_CB(skb)->bytes_read) { + __skb_unlink(skb, &sk->sk_receive_queue); + kfree_skb(skb); }
- if (tipc_sk_type_connectionless(sk)) + /* Reject all unreceived messages if connectionless */ + if (tipc_sk_type_connectionless(sk)) { + tsk_rej_rx_queue(sk, error); return; + }
- if (sk->sk_state != TIPC_DISCONNECTING) { + switch (sk->sk_state) { + case TIPC_CONNECTING: + case TIPC_ESTABLISHED: + tipc_set_sk_state(sk, TIPC_DISCONNECTING); + tipc_node_remove_conn(net, dnode, tsk->portid); + /* Send a FIN+/- to its peer */ + skb = __skb_dequeue(&sk->sk_receive_queue); + if (skb) { + __skb_queue_purge(&sk->sk_receive_queue); + tipc_sk_respond(sk, skb, error); + break; + } skb = tipc_msg_create(TIPC_CRITICAL_IMPORTANCE, TIPC_CONN_MSG, SHORT_H_SIZE, 0, dnode, tsk_own_node(tsk), tsk_peer_port(tsk), tsk->portid, error); if (skb) tipc_node_xmit_skb(net, skb, dnode, tsk->portid); - tipc_node_remove_conn(net, dnode, tsk->portid); - tipc_set_sk_state(sk, TIPC_DISCONNECTING); + break; + case TIPC_LISTEN: + /* Reject all SYN messages */ + tsk_rej_rx_queue(sk, error); + break; + default: + __skb_queue_purge(&sk->sk_receive_queue); + break; } }
@@ -2564,7 +2575,7 @@ static int tipc_accept(struct socket *sock, struct socket *new_sock, int flags, * Reject any stray messages received by new socket * before the socket lock was taken (very, very unlikely) */ - tsk_rej_rx_queue(new_sk); + tsk_rej_rx_queue(new_sk, TIPC_ERR_NO_PORT);
/* Connect new socket to it's peer */ tipc_sk_finish_conn(new_tsock, msg_origport(msg), msg_orignode(msg));