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authorJon Paul Maloy <jon.maloy@ericsson.com>2016-10-27 18:51:55 -0400
committerDavid S. Miller <davem@davemloft.net>2016-10-29 17:21:09 -0400
commit06bd2b1ed04ca9fdbc767859885944a1e8b86b40 (patch)
tree7e7d6b57da043b23bde4b7e72a5cfeaa8294dd39 /net/tipc/bcast.c
parent8bf371e6adff29758cc3c57c17df4486513081f8 (diff)
downloadlinux-06bd2b1ed04ca9fdbc767859885944a1e8b86b40.tar.bz2
tipc: fix broadcast link synchronization problem
In commit 2d18ac4ba745 ("tipc: extend broadcast link initialization criteria") we tried to fix a problem with the initial synchronization of broadcast link acknowledge values. Unfortunately that solution is not sufficient to solve the issue. We have seen it happen that LINK_PROTOCOL/STATE packets with a valid non-zero unicast acknowledge number may bypass BCAST_PROTOCOL initialization, NAME_DISTRIBUTOR and other STATE packets with invalid broadcast acknowledge numbers, leading to premature opening of the broadcast link. When the bypassed packets finally arrive, they are inadvertently accepted, and the already correctly initialized acknowledge number in the broadcast receive link is overwritten by the invalid (zero) value of the said packets. After this the broadcast link goes stale. We now fix this by marking the packets where we know the acknowledge value is or may be invalid, and then ignoring the acks from those. To this purpose, we claim an unused bit in the header to indicate that the value is invalid. We set the bit to 1 in the initial BCAST_PROTOCOL synchronization packet and all initial ("bulk") NAME_DISTRIBUTOR packets, plus those LINK_PROTOCOL packets sent out before the broadcast links are fully synchronized. This minor protocol update is fully backwards compatible. Reported-by: John Thompson <thompa.atl@gmail.com> Tested-by: John Thompson <thompa.atl@gmail.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc/bcast.c')
-rw-r--r--net/tipc/bcast.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 753f774cb46f..aa1babbea385 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -247,11 +247,17 @@ int tipc_bcast_rcv(struct net *net, struct tipc_link *l, struct sk_buff *skb)
*
* RCU is locked, no other locks set
*/
-void tipc_bcast_ack_rcv(struct net *net, struct tipc_link *l, u32 acked)
+void tipc_bcast_ack_rcv(struct net *net, struct tipc_link *l,
+ struct tipc_msg *hdr)
{
struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq;
+ u16 acked = msg_bcast_ack(hdr);
struct sk_buff_head xmitq;
+ /* Ignore bc acks sent by peer before bcast synch point was received */
+ if (msg_bc_ack_invalid(hdr))
+ return;
+
__skb_queue_head_init(&xmitq);
tipc_bcast_lock(net);
@@ -279,11 +285,11 @@ int tipc_bcast_sync_rcv(struct net *net, struct tipc_link *l,
__skb_queue_head_init(&xmitq);
tipc_bcast_lock(net);
- if (msg_type(hdr) == STATE_MSG) {
+ if (msg_type(hdr) != STATE_MSG) {
+ tipc_link_bc_init_rcv(l, hdr);
+ } else if (!msg_bc_ack_invalid(hdr)) {
tipc_link_bc_ack_rcv(l, msg_bcast_ack(hdr), &xmitq);
rc = tipc_link_bc_sync_rcv(l, hdr, &xmitq);
- } else {
- tipc_link_bc_init_rcv(l, hdr);
}
tipc_bcast_unlock(net);