From b53686c52a592e5edf0d89f92ec9a2b83fc4e470 Mon Sep 17 00:00:00 2001
From: Philippe Guibert <philippe.guibert@6wind.com>
Date: Fri, 16 Mar 2018 18:37:08 +0100
Subject: [PATCH] zebra: delete interface that disappeared

When moving interfaces to an other place, like other netns, the
remaining interface is still present, with inactive status.
Now, that interface is deleted from the list, if the interface appears
on an other netns. If not, the interface is kept.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
---
 zebra/if_netlink.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++
 zebra/interface.c  | 24 +++++++++++++++++++++
 zebra/interface.h  |  2 ++
 3 files changed, 80 insertions(+)

diff --git a/zebra/if_netlink.c b/zebra/if_netlink.c
index a37d74416b..47c99127c7 100644
--- a/zebra/if_netlink.c
+++ b/zebra/if_netlink.c
@@ -1008,6 +1008,54 @@ int netlink_interface_addr(struct sockaddr_nl *snl, struct nlmsghdr *h,
 	return 0;
 }
 
+/* helper function called by if_netlink_change
+ * to delete interfaces in case the interface moved
+ * to an other netns
+ */
+static void if_netlink_check_ifp_instance_consistency(uint16_t cmd,
+						     struct interface *ifp,
+						     ns_id_t ns_id)
+{
+	struct interface *old_ifp;
+
+	/*
+	 * look if interface name is also found on other netns
+	 * - only if vrf backend is netns
+	 * - do not concern lo interface
+	 * - then remove previous one
+	 * - for new link case, check found interface is not active
+	 */
+	if (!vrf_is_backend_netns() ||
+	    !strcmp(ifp->name, "lo"))
+		return;
+	old_ifp = if_lookup_by_name_not_ns(ns_id, ifp->name);
+	if (!old_ifp)
+		return;
+	if ((cmd == RTM_NEWLINK)
+	    && (CHECK_FLAG(old_ifp->status, ZEBRA_INTERFACE_ACTIVE)))
+		return;
+	if (IS_ZEBRA_DEBUG_KERNEL)
+		zlog_debug("%s %s(%u) %s VRF %u",
+			   cmd == RTM_DELLINK ?
+			   "RTM_DELLINK replaced by" :
+			   "RTM_NEWLINK replaces",
+			   ifp->name,
+			   old_ifp->ifindex,
+			   cmd == RTM_DELLINK ?
+			   "in" : "from",
+			   old_ifp->vrf_id);
+	/* the found interface replaces the current one
+	 * remove it
+	 */
+	if (cmd == RTM_DELLINK)
+		if_delete(ifp);
+	else
+		if_delete(old_ifp);
+	/* the found interface is replaced by the current one
+	 * suppress it
+	 */
+}
+
 int netlink_link_change(struct sockaddr_nl *snl, struct nlmsghdr *h,
 			ns_id_t ns_id, int startup)
 {
@@ -1169,6 +1217,8 @@ int netlink_link_change(struct sockaddr_nl *snl, struct nlmsghdr *h,
 			if (IS_ZEBRA_IF_BRIDGE_SLAVE(ifp))
 				zebra_l2if_update_bridge_slave(ifp,
 							       bridge_ifindex);
+			if_netlink_check_ifp_instance_consistency(RTM_NEWLINK,
+								  ifp, ns_id);
 		} else if (ifp->vrf_id != vrf_id) {
 			/* VRF change for an interface. */
 			if (IS_ZEBRA_DEBUG_KERNEL)
@@ -1236,6 +1286,8 @@ int netlink_link_change(struct sockaddr_nl *snl, struct nlmsghdr *h,
 			if (IS_ZEBRA_IF_BRIDGE_SLAVE(ifp) || was_bridge_slave)
 				zebra_l2if_update_bridge_slave(ifp,
 							       bridge_ifindex);
+			if_netlink_check_ifp_instance_consistency(RTM_NEWLINK,
+								  ifp, ns_id);
 		}
 	} else {
 		/* Delete interface notification from kernel */
@@ -1259,6 +1311,8 @@ int netlink_link_change(struct sockaddr_nl *snl, struct nlmsghdr *h,
 
 		if (!IS_ZEBRA_IF_VRF(ifp))
 			if_delete_update(ifp);
+		if_netlink_check_ifp_instance_consistency(RTM_DELLINK,
+							  ifp, ns_id);
 	}
 
 	return 0;
diff --git a/zebra/interface.c b/zebra/interface.c
index 01283f9122..8d3639b315 100644
--- a/zebra/interface.c
+++ b/zebra/interface.c
@@ -252,6 +252,30 @@ struct interface *if_lookup_by_name_per_ns(struct zebra_ns *ns,
 	return NULL;
 }
 
+/* this function must be used only if the vrf backend
+ * is a netns backend
+ */
+struct interface *if_lookup_by_name_not_ns(ns_id_t ns_id,
+					   const char *ifname)
+{
+	struct interface *ifp;
+	struct ns *ns;
+
+	RB_FOREACH (ns, ns_head, &ns_tree) {
+		if (ns->ns_id == ns_id)
+			continue;
+		/* if_delete_update has removed interface
+		 * from zns->if_table
+		 * so to look for interface, use the vrf list
+		 */
+		ifp = if_lookup_by_name(ifname, (vrf_id_t)ns->ns_id);
+		if (!ifp)
+			continue;
+		return ifp;
+	}
+	return NULL;
+}
+
 const char *ifindex2ifname_per_ns(struct zebra_ns *zns, unsigned int ifindex)
 {
 	struct interface *ifp;
diff --git a/zebra/interface.h b/zebra/interface.h
index 9f109fc05f..f01864c9fb 100644
--- a/zebra/interface.h
+++ b/zebra/interface.h
@@ -318,6 +318,8 @@ extern struct interface *if_lookup_by_index_per_ns(struct zebra_ns *,
 						   u_int32_t);
 extern struct interface *if_lookup_by_name_per_ns(struct zebra_ns *,
 						  const char *);
+extern struct interface *if_lookup_by_name_not_ns(ns_id_t ns_id,
+						  const char *ifname);
 extern struct interface *if_link_per_ns(struct zebra_ns *, struct interface *);
 extern const char *ifindex2ifname_per_ns(struct zebra_ns *, unsigned int);
 
-- 
2.39.5