tipc: guarantee group unicast doesn't bypass group broadcast

Group unicast messages don't follow the same path as broadcast messages,
and there is a high risk that unicasts sent from a socket might bypass
previously sent broadcasts from the same socket.

We fix this by letting all unicast messages carry the sequence number of
the next sent broadcast from the same node, but without updating this
number at the receiver. This way, a receiver can check and if necessary
re-order such messages before they are added to the socket receive buffer.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 8fdd969e12bd..3276b7a0d445 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -830,6 +830,7 @@ static int tipc_send_group_msg(struct net *net, struct tipc_sock *tsk,
                                struct msghdr *m, struct tipc_member *mb,
                                u32 dnode, u32 dport, int dlen)
 {
+        u16 bc_snd_nxt = tipc_group_bc_snd_nxt(tsk->group);
         int blks = tsk_blocks(GROUP_H_SIZE + dlen);
         struct tipc_msg *hdr = &tsk->phdr;
         struct sk_buff_head pkts;
@@ -840,6 +841,7 @@ static int tipc_send_group_msg(struct net *net, struct tipc_sock *tsk,
         msg_set_hdr_sz(hdr, GROUP_H_SIZE);
         msg_set_destport(hdr, dport);
         msg_set_destnode(hdr, dnode);
+        msg_set_grp_bc_seqno(hdr, bc_snd_nxt);
 
         /* Build message as chain of buffers */
         skb_queue_head_init(&pkts);