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authorAllan Stephens <allan.stephens@windriver.com>2011-10-29 01:30:08 +0400
committerPaul Gortmaker <paul.gortmaker@windriver.com>2012-02-25 02:05:13 +0400
commit97878a405c0ffe0f6433e1fb51834d4619ece025 (patch)
tree1893ca2ba6775bcac3cc336e41fe96dac10fd96f /net/tipc/discover.c
parentfc0eea691a06ba8516795fb7a198239fb9db1cfc (diff)
downloadlinux-97878a405c0ffe0f6433e1fb51834d4619ece025.tar.xz
tipc: Detect duplicate nodes using different network interfaces
Utilizes the new "node signature" field in neighbor discovery messages to ensure that all links TIPC associates with a given <Z.C.N> network address belong to the same neighboring node. (Previously, TIPC could not tell if link setup requests arriving on different interfaces were from the same node or from two different nodes that has mistakenly been assigned the same network address.) The revised algorithm for detecting a duplicate node considers both the node signature and the network interface adddress specified in a request message when deciding how to respond to a link setup request. This prevents false alarms that might otherwise arise during normal network operation under the following scenarios: a) A neighboring node reboots. (The node's signature changes, but the network interface address remains unchanged.) b) A neighboring node's network interface is replaced. (The node's signature remains unchanged, but the network interface address changes.) c) A neighboring node is completely replaced. (The node's signature and network interface address both change.) The algorithm also handles cases in which a node reboots and re-establishes its links to TIPC (or begins re-establishing those links) before TIPC detects that it is using a new node signature. In such cases of "delayed rediscovery" TIPC simply accepts the new signature without disrupting communication that is already underway over the links. Thanks to Laser [gotolaser@gmail.com] for his contributions to the development of this enhancement. Signed-off-by: Allan Stephens <allan.stephens@windriver.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Diffstat (limited to 'net/tipc/discover.c')
-rw-r--r--net/tipc/discover.c72
1 files changed, 58 insertions, 14 deletions
diff --git a/net/tipc/discover.c b/net/tipc/discover.c
index 7ae1b4c33aeb..f5f9bf7a0436 100644
--- a/net/tipc/discover.c
+++ b/net/tipc/discover.c
@@ -122,7 +122,7 @@ void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
{
struct tipc_node *n_ptr;
struct tipc_link *link;
- struct tipc_media_addr media_addr, *addr;
+ struct tipc_media_addr media_addr;
struct sk_buff *rbuf;
struct tipc_msg *msg = buf_msg(buf);
u32 dest = msg_dest_domain(msg);
@@ -130,13 +130,14 @@ void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
u32 net_id = msg_bc_netid(msg);
u32 type = msg_type(msg);
u32 signature = msg_node_sig(msg);
+ int addr_mismatch;
int link_fully_up;
media_addr.broadcast = 1;
b_ptr->media->msg2addr(&media_addr, msg_media_addr(msg));
buf_discard(buf);
- /* Validate discovery message from requesting node */
+ /* Ensure message from node is valid and communication is permitted */
if (net_id != tipc_net_id)
return;
if (media_addr.broadcast)
@@ -164,15 +165,50 @@ void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
}
tipc_node_lock(n_ptr);
+ /* Prepare to validate requesting node's signature and media address */
link = n_ptr->links[b_ptr->identity];
+ addr_mismatch = (link != NULL) &&
+ memcmp(&link->media_addr, &media_addr, sizeof(media_addr));
- /* Create a link endpoint for this bearer, if necessary */
- if (!link) {
- link = tipc_link_create(n_ptr, b_ptr, &media_addr);
- if (!link) {
+ /*
+ * Ensure discovery message's signature is correct
+ *
+ * If signature is incorrect and there is no working link to the node,
+ * accept the new signature but invalidate all existing links to the
+ * node so they won't re-activate without a new discovery message.
+ *
+ * If signature is incorrect and the requested link to the node is
+ * working, accept the new signature. (This is an instance of delayed
+ * rediscovery, where a link endpoint was able to re-establish contact
+ * with its peer endpoint on a node that rebooted before receiving a
+ * discovery message from that node.)
+ *
+ * If signature is incorrect and there is a working link to the node
+ * that is not the requested link, reject the request (must be from
+ * a duplicate node).
+ */
+ if (signature != n_ptr->signature) {
+ if (n_ptr->working_links == 0) {
+ struct tipc_link *curr_link;
+ int i;
+
+ for (i = 0; i < MAX_BEARERS; i++) {
+ curr_link = n_ptr->links[i];
+ if (curr_link) {
+ memset(&curr_link->media_addr, 0,
+ sizeof(media_addr));
+ tipc_link_reset(curr_link);
+ }
+ }
+ addr_mismatch = (link != NULL);
+ } else if (tipc_link_is_up(link) && !addr_mismatch) {
+ /* delayed rediscovery */
+ } else {
+ disc_dupl_alert(b_ptr, orig, &media_addr);
tipc_node_unlock(n_ptr);
return;
}
+ n_ptr->signature = signature;
}
/*
@@ -185,21 +221,29 @@ void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
* the new media address and reset the link to ensure it starts up
* cleanly.
*/
- addr = &link->media_addr;
- if (memcmp(addr, &media_addr, sizeof(*addr))) {
- if (tipc_link_is_up(link) || (!link->started)) {
+
+ if (addr_mismatch) {
+ if (tipc_link_is_up(link)) {
disc_dupl_alert(b_ptr, orig, &media_addr);
tipc_node_unlock(n_ptr);
return;
+ } else {
+ memcpy(&link->media_addr, &media_addr,
+ sizeof(media_addr));
+ tipc_link_reset(link);
+ }
+ }
+
+ /* Create a link endpoint for this bearer, if necessary */
+ if (!link) {
+ link = tipc_link_create(n_ptr, b_ptr, &media_addr);
+ if (!link) {
+ tipc_node_unlock(n_ptr);
+ return;
}
- warn("Resetting link <%s>, peer interface address changed\n",
- link->name);
- memcpy(addr, &media_addr, sizeof(*addr));
- tipc_link_reset(link);
}
/* Accept discovery message & send response, if necessary */
- n_ptr->signature = signature;
link_fully_up = link_working_working(link);
if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {