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) {