Before signalling capture to revoke access to the tty device, change the

mode so no one can open it between the time capture does the revocation
and we change the group/mode to the new user.

tbsetup/console_setup.proxy

@@ -121,6 +121,15 @@ foreach my $node ( keys %nodepid ) {
     chmod(0640, $filename) or
 	die("Could not chmod(0640) $filename: $!");
 
+    #
+    # Remove group access from the tty device.  This renders the device
+    # inaccessible to both old and new users while we revoke access from
+    # any current tip user.
+    #
+    $tipdevname = "$TIPDEVDIR/$node";
+    chmod(0600, $tipdevname) or
+	die("Could not chmod(0600) $tipdevname: $!");
+
     #
     # Now send a USR2 signal to the capture process so that it closes down
     # any tip thats attached to it.
@@ -129,11 +138,10 @@ foreach my $node ( keys %nodepid ) {
 	die("Could not signal(USR2) process $procid for log $filename");
 
     #
-    # Set the mode and group for the tty that tip is going to use. This
-    # allows the user to access the tip line using a non-setuid version
-    # of tip.
+    # Set the mode and group on the tty that tip is going to use. This
+    # allows the new group to access the tip line using a non-setuid/gid
+    # program.
     #
-    $tipdevname = "$TIPDEVDIR/$node";
     chown(0, $gid, $tipdevname) or
 	die("Could not chown(0, $gid) $tipdevname: $!");
     chmod(0660, $tipdevname) or

tbsetup/console_setup.proxy.in

@@ -121,6 +121,15 @@ foreach my $node ( keys %nodepid ) {
     chmod(0640, $filename) or
 	die("Could not chmod(0640) $filename: $!");
 
+    #
+    # Remove group access from the tty device.  This renders the device
+    # inaccessible to both old and new users while we revoke access from
+    # any current tip user.
+    #
+    $tipdevname = "$TIPDEVDIR/$node";
+    chmod(0600, $tipdevname) or
+	die("Could not chmod(0600) $tipdevname: $!");
+
     #
     # Now send a USR2 signal to the capture process so that it closes down
     # any tip thats attached to it.
@@ -129,11 +138,10 @@ foreach my $node ( keys %nodepid ) {
 	die("Could not signal(USR2) process $procid for log $filename");
 
     #
-    # Set the mode and group for the tty that tip is going to use. This
-    # allows the user to access the tip line using a non-setuid version
-    # of tip.
+    # Set the mode and group on the tty that tip is going to use. This
+    # allows the new group to access the tip line using a non-setuid/gid
+    # program.
     #
-    $tipdevname = "$TIPDEVDIR/$node";
     chown(0, $gid, $tipdevname) or
 	die("Could not chown(0, $gid) $tipdevname: $!");
     chmod(0660, $tipdevname) or