netlink: workaround veth being peered together through IFLA_LINK

This is a change introduced in Linux 4.1. It's easy to detect, so,
workaround it. See:

    commit a45253bf32bf49cdb2807bad212b84f5ab51ac26
    Author: Nicolas Dichtel <nicolas.dichtel@6wind.com>
    Date:   Thu Apr 2 17:07:11 2015 +0200

        veth: set iflink to the peer veth

        Now that the peer netns is advertised in rtnl messages, we can set this property
        so that IFLA_LINK will advertise the peer ifindex. It allows the userland to get
        the full veth configuration.

        Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
        Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/src/daemon/netlink.c b/src/daemon/netlink.c
index 694e4e34f0266a21d92feca9b2c0da457460a72c..1bc606a30d316f39e99fe439bfea12220754bf5a 100644 (file)
--- a/src/daemon/netlink.c
+++ b/src/daemon/netlink.c
@@ -267,9 +267,17 @@ netlink_get_interfaces(struct lldpd *cfg)
                if (iface1->lower_idx != 0 && iface1->lower_idx != iface1->index)
                        TAILQ_FOREACH(iface2, ifs, next) {
                                if (iface1->lower_idx == iface2->index) {
-                                       log_debug("netlink", "%s is lower iface for %s",
-                                           iface2->name, iface1->name);
-                                       iface1->lower = iface2;
+                                       if (iface2->lower_idx == iface1->index) {
+                                               log_debug("netlink", "%s and %s are peered together",
+                                                   iface1->name, iface2->name);
+                                               /* Workaround a bug introduced in Linux 4.1 */
+                                               iface2->lower_idx = iface2->index;
+                                               iface1->lower_idx = iface1->index;
+                                       } else {
+                                               log_debug("netlink", "%s is lower iface for %s",
+                                                   iface2->name, iface1->name);
+                                               iface1->lower = iface2;
+                                       }
                                        break;
                                }
                        }