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platform: drop workaround for deleting IPv4 routes with metric zero

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Deleting an IPv4 route with metric zero will either delete the intended route,
or if no such route exists, it will delete another existing route with different
metric (but otherwise matching parameters).

I think this is a shortcoming of the kernel API. It allows omitting
the metric during delete. However, it gives not way to express to
explicitly delete an IPv4 route with metric zero, but no other.

Since we only delete routes that we obtain from the platform cache
in the first place, we don't need the workaround. Of course, there
is still a race that platform cache might be out of date at the
moment we attempt to delete the route. Or the cache might be
inconsistent, both cases leading to deletion of the wrong route.
But such cases should be very rare, and only present when the user
changes the routing table outside of NM.
This commit is contained in:
Thomas Haller
2017-08-11 09:44:15 +02:00
parent cdd8c65799
commit 3ec110b67e
1 changed files with 0 additions and 31 deletions
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31
src/platform/nm-linux-platform.c
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@@ -5879,37 +5879,6 @@ ip_route_delete (NMPlatform *platform,
if (!NMP_OBJECT_IS_STACKINIT (obj))
obj_keep_alive = nmp_object_ref (obj);
if ( NMP_OBJECT_GET_TYPE (obj) == NMP_OBJECT_TYPE_IP4_ROUTE
&& obj->ip_route.metric == 0) {
NMPCache *cache = nm_platform_get_cache (platform);
/* Deleting an IPv4 route with metric 0 does not only delete an exectly matching route.
* If no route with metric 0 exists, it might delete another route to the same destination.
* For nm_platform_ip4_route_delete() we don't want this semantic.
*
* Instead, make sure that we have the most recent state and process all
* delayed actions (including re-reading data from netlink). */
/* FIXME: later, we only want to pass in here @obj instances that originate
* from the cache, and where we know that the route with metric 0 exists. */
delayed_action_handle_all (platform, TRUE);
if (!nmp_cache_lookup_obj (cache, obj)) {
/* hmm... we are about to delete an IP4 route with metric 0. We must only
* send the delete request if such a route really exists. Above we refreshed
* the platform cache, still no such route exists.
*
* Be extra careful and reload the routes. We must be sure that such a
* route doesn't exists, because when we add an IPv4 address, we immediately
* afterwards try to delete the kernel-added device route with metric 0.
* It might be, that we didn't yet get the notification about that route. */
do_request_one_type (platform, NMP_OBJECT_TYPE_IP4_ROUTE);
if (!nmp_cache_lookup_obj (cache, obj))
return TRUE;
}
}
nlmsg = _nl_msg_new_route (RTM_DELROUTE, 0, obj);
if (!nlmsg)
g_return_val_if_reached (FALSE);