Merge pull request #12457 from donaldsharp/nexthop_free

bgpd: BGP fails to free the nexthop node

bgpd/bgp_nht.c

@@ -212,6 +212,37 @@ void bgp_replace_nexthop_by_peer(struct peer *from, struct peer *to)
 		bnct->nht_info = to;
 }
 
+/*
+ * Returns the bnc whose bnc->nht_info matches the LL peer by
+ * looping through the IPv6 nexthop table
+ */
+static struct bgp_nexthop_cache *
+bgp_find_ipv6_nexthop_matching_peer(struct peer *peer)
+{
+	struct bgp_nexthop_cache *bnc;
+
+	frr_each (bgp_nexthop_cache, &peer->bgp->nexthop_cache_table[AFI_IP6],
+		  bnc) {
+		if (bnc->nht_info == peer) {
+			if (BGP_DEBUG(nht, NHT)) {
+				zlog_debug(
+					"Found bnc: %pFX(%u)(%u)(%p) for peer: %s(%s) %p",
+					&bnc->prefix, bnc->ifindex,
+					bnc->srte_color, bnc, peer->host,
+					peer->bgp->name_pretty, peer);
+			}
+			return bnc;
+		}
+	}
+
+	if (BGP_DEBUG(nht, NHT))
+		zlog_debug(
+			"Could not find bnc for peer %s(%s) %p in v6 nexthop table",
+			peer->host, peer->bgp->name_pretty, peer);
+
+	return NULL;
+}
+
 void bgp_unlink_nexthop_by_peer(struct peer *peer)
 {
 	struct prefix p;
@@ -219,15 +250,30 @@ void bgp_unlink_nexthop_by_peer(struct peer *peer)
 	afi_t afi = family2afi(peer->su.sa.sa_family);
 	ifindex_t ifindex = 0;
 
-	if (!sockunion2hostprefix(&peer->su, &p))
-		return;
-	/*
-	 * Gather the ifindex for if up/down events to be
-	 * tagged into this fun
-	 */
-	if (afi == AFI_IP6 && IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
-		ifindex = peer->su.sin6.sin6_scope_id;
-	bnc = bnc_find(&peer->bgp->nexthop_cache_table[afi], &p, 0, ifindex);
+	if (!sockunion2hostprefix(&peer->su, &p)) {
+		/*
+		 * In scenarios where unnumbered BGP session is brought
+		 * down by shutting down the interface before unconfiguring
+		 * the BGP neighbor, neighbor information in peer->su.sa
+		 * will be cleared when the interface is shutdown. So
+		 * during the deletion of unnumbered bgp peer, above check
+		 * will return true. Therefore, in this case,BGP needs to
+		 * find the bnc whose bnc->nht_info matches the
+		 * peer being deleted and free it.
+		 */
+		bnc = bgp_find_ipv6_nexthop_matching_peer(peer);
+	} else {
+		/*
+		 * Gather the ifindex for if up/down events to be
+		 * tagged into this fun
+		 */
+		if (afi == AFI_IP6 &&
+		    IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
+			ifindex = peer->su.sin6.sin6_scope_id;
+		bnc = bnc_find(&peer->bgp->nexthop_cache_table[afi], &p, 0,
+			       ifindex);
+	}
+
 	if (!bnc)
 		return;
 
@@ -443,6 +489,15 @@ void bgp_delete_connected_nexthop(afi_t afi, struct peer *peer)
 	if (!peer)
 		return;
 
+	/*
+	 * In case the below check evaluates true and if
+	 * the bnc has not been freed at this point, then
+	 * we might have to do something similar to what's
+	 * done in bgp_unlink_nexthop_by_peer(). Since
+	 * bgp_unlink_nexthop_by_peer() loops through the
+	 * nodes of V6 nexthop cache to find the bnc, it is
+	 * currently not being called here.
+	 */
 	if (!sockunion2hostprefix(&peer->su, &p))
 		return;
 	/*

tests/topotests/bgp_unnumbered/r1/bgpd.conf

@@ -0,0 +1,9 @@
+!
+router bgp 65001
+  timers bgp 1 9
+  no bgp ebgp-requires-policy
+  neighbor r1-eth0 interface remote-as external
+  address-family ipv4 unicast
+  exit-address-family
+ !
+!

tests/topotests/bgp_unnumbered/r1/zebra.conf

@@ -0,0 +1,10 @@
+!
+interface lo
+ ip address 172.16.250.254/32
+!
+interface r1-eth0
+ ip address 192.168.0.1/24
+!
+ip forwarding
+!
+

tests/topotests/bgp_unnumbered/r2/bgpd.conf

@@ -0,0 +1,9 @@
+!
+router bgp 65002
+  no bgp network import-check
+  no bgp ebgp-requires-policy
+  timers bgp 1 9
+  neighbor r2-eth0 interface remote-as external
+  address-family ipv4 uni
+    network 172.16.255.254/32
+!

tests/topotests/bgp_unnumbered/r2/zebra.conf

@@ -0,0 +1,12 @@
+!
+interface r2-eth0
+ ip address 192.168.0.2/24
+!
+interface r2-eth1
+ ip address 192.168.1.1/24
+!
+interface r2-eth2
+ ip address 192.168.2.1/24
+!
+ip forwarding
+!

tests/topotests/bgp_unnumbered/test_bgp_unnumbered.py

@@ -0,0 +1,132 @@
+#!/usr/bin/env python
+#
+# Copyright (c) 2022 by
+# Donald Sharp
+#
+# Permission to use, copy, modify, and/or distribute this software
+# for any purpose with or without fee is hereby granted, provided
+# that the above copyright notice and this permission notice appear
+# in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NETDEF DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NETDEF BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+#
+
+"""
+Test some bgp interface based issues that show up
+"""
+
+import os
+import sys
+import json
+import pytest
+import functools
+
+CWD = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(CWD, "../"))
+
+# pylint: disable=C0413
+from lib import topotest
+from lib.topogen import Topogen, TopoRouter, get_topogen
+from lib.common_config import step
+
+pytestmark = [pytest.mark.bgpd]
+
+
+def build_topo(tgen):
+
+    tgen.add_router("r1")
+    tgen.add_router("r2")
+
+    switch = tgen.add_switch("s1")
+    switch.add_link(tgen.gears["r1"])
+    switch.add_link(tgen.gears["r2"])
+
+
+def setup_module(mod):
+    tgen = Topogen(build_topo, mod.__name__)
+    tgen.start_topology()
+
+    router_list = tgen.routers()
+
+    for i, (rname, router) in enumerate(router_list.items(), 1):
+        router.load_config(
+            TopoRouter.RD_ZEBRA, os.path.join(CWD, "{}/zebra.conf".format(rname))
+        )
+        router.load_config(
+            TopoRouter.RD_BGP, os.path.join(CWD, "{}/bgpd.conf".format(rname))
+        )
+
+    tgen.start_router()
+
+
+def teardown_module(mod):
+    tgen = get_topogen()
+    tgen.stop_topology()
+
+
+#
+# Test these events:
+# a) create an unnumbered neighbor
+# b) shutdown the interface
+# c) remove the unnumbered peer in bgp and bgp does not crash
+def test_bgp_unnumbered_removal():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _bgp_nexthop_cache():
+        output = tgen.gears["r1"].vtysh_cmd("show bgp nexthop")
+        expected = "Current BGP nexthop cache:\n"
+        return output == expected
+
+    def _bgp_converge():
+        output = json.loads(
+            tgen.gears["r1"].vtysh_cmd("show ip bgp 172.16.255.254/32 json")
+        )
+        expected = {"prefix": "172.16.255.254/32"}
+
+        return topotest.json_cmp(output, expected)
+
+    step("Ensure Convergence of BGP")
+    test_func = functools.partial(_bgp_converge)
+    success, result = topotest.run_and_expect(test_func, None, count=60, wait=1)
+
+    assert result is None, 'Failed bgp convergence in "{}"'.format(tgen.gears["r2"])
+
+    step("Shutdown interface r1-eth0")
+
+    tgen.gears["r1"].vtysh_cmd(
+        """
+           configure
+           int r1-eth0
+             shutdown
+        """
+    )
+
+    step("Remove the neighbor from r1")
+    tgen.gears["r1"].vtysh_cmd(
+        """
+           configure
+           router bgp
+            no neighbor r1-eth0 interface remote-as external
+       """
+    )
+
+    step("Ensure that BGP does not crash")
+    test_func = functools.partial(_bgp_nexthop_cache)
+    success, result = topotest.run_and_expect(test_func, True, count=10, wait=1)
+
+    assert result is True, "BGP did not crash on r1"
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))