[PATCH v4] Add check that username is identical to multi float

From: Arne Schwabe <[email protected]>

This adds an additional safe guard for setups that do not use
client certificates.

Change-Id: Ie552084638320b3bace76be2f589013f12af3c46
Signed-off-by: Arne Schwabe <[email protected]>
Acked-by: Frank Lichtenheld <[email protected]>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1724
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1724
This mail reflects revision 4 of this Change.

Acked-by according to Gerrit (reflected above):
Frank Lichtenheld <[email protected]>

        
diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index c40ebe4..ce6807e 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -3115,6 +3115,18 @@
         goto done;
     }
 
+    /* do not allow if target address has a different username */
+    if (m1->locked_username || m2->locked_username)
+    {
+        if (!m1->locked_username || !m2->locked_username
+            || strcmp(m1->locked_username, m2->locked_username) != 0)
+        {
+            msg(D_MULTI_LOW, "Disallow float to an address taken by another client %s",
+                multi_instance_string(ex_mi, false, &gc));
+            goto done;
+        }
+    }
+
     /* It doesn't make sense to let a peer float to the address it already
      * has, so we disallow it. This can happen if a DCO netlink notification
      * gets lost and we miss a floating step.
@@ -3131,7 +3143,7 @@
 
     msg(D_MULTI_LOW,
         "closing instance %s due to float collision with %s "
-        "using the same certificate",
+        "using the same certificate and username",
         multi_instance_string(ex_mi, false, &gc), multi_instance_string(mi, false, &gc));
     multi_close_instance(m, ex_mi, false);
     ret = true;