tipc: add SYN bit to connection setup messages

Messages intended for intitating a connection are currently
indistinguishable from regular datagram messages. The TIPC
protocol specification defines bit 17 in word 0 as a SYN bit
to allow sanity check of such messages in the listening socket,
but this has so far never been implemented.

We do that in this commit.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 094cfdc1e2b6..89d6dc0f456d 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1319,6 +1319,7 @@ static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dlen)
                         tsk->conn_type = dest->addr.name.name.type;
                         tsk->conn_instance = dest->addr.name.name.instance;
                 }
+                msg_set_syn(hdr, 1);
         }
 
         seq = &dest->addr.nameseq;
@@ -1478,6 +1479,7 @@ static void tipc_sk_finish_conn(struct tipc_sock *tsk, u32 peer_port,
         struct net *net = sock_net(sk);
         struct tipc_msg *msg = &tsk->phdr;
 
+        msg_set_syn(msg, 0);
         msg_set_destnode(msg, peer_node);
         msg_set_destport(msg, peer_port);
         msg_set_type(msg, TIPC_CONN_MSG);
@@ -2006,6 +2008,9 @@ static bool tipc_sk_filter_connect(struct tipc_sock *tsk, struct sk_buff *skb)
                 return false;
         case TIPC_LISTEN:
                 /* Accept only SYN message */
+                if (!msg_is_syn(hdr) &&
+                    tipc_node_get_capabilities(net, onode) & TIPC_SYN_BIT)
+                        return false;
                 if (!con_msg && !err)
                         return true;
                 return false;