Merge branch 'ipv6-ipv4-nexthop-align'

Ido Schimmel says:

====================
ipv6: Align nexthop behaviour with IPv4

This set tries to eliminate some differences between IPv4's and IPv6's
treatment of nexthops. These differences are most likely a side effect
of IPv6's data structures (specifically 'rt6_info') that incorporate
both the route and the nexthop and the late addition of ECMP support in
commit 51ebd3181572 ("ipv6: add support of equal cost multipath
(ECMP)").

IPv4 and IPv6 do not react the same to certain netdev events. For
example, upon carrier change affected IPv4 nexthops are marked using the
RTNH_F_LINKDOWN flag and the nexthop group is rebalanced accordingly.
IPv6 on the other hand, does nothing which forces us to perform a
carrier check during route lookup and dump. This makes it difficult to
introduce features such as non-equal-cost multipath that are built on
top of this set [1].

In addition, when a netdev is put administratively down IPv4 nexthops
are marked using the RTNH_F_DEAD flag, whereas IPv6 simply flushes all
the routes using these nexthops. To be consistent with IPv4, multipath
routes should only be flushed when all nexthops in the group are
considered dead.

The first 12 patches introduce non-functional changes that store the
RTNH_F_DEAD and RTNH_F_LINKDOWN flags in IPv6 routes based on netdev
events, in a similar fashion to IPv4. This allows us to remove the
carrier check performed during route lookup and dump.

The next three patches make sure we only flush a multipath route when
all of its nexthops are dead.

Last three patches add test cases for IPv4/IPv6 FIB. These verify that
both address families react similarly to netdev events.

Finally, this series also serves as a good first step towards David
Ahern's goal of treating nexthops as standalone objects [2], as it makes
the code more in line with IPv4 where the nexthop and the nexthop group
are separate objects from the route itself.

1. https://github.com/idosch/linux/tree/ipv6-nexthops
2. http://vger.kernel.org/netconf2017_files/nexthop-objects.pdf

Changes since RFC (feedback from David Ahern):
* Remove redundant declaration of rt6_ifdown() in patch 4 and adjust
comment referencing it accordingly
* Drop patch to flush multipath routes upon NETDEV_UNREGISTER. Reword
cover letter accordingly
* Use a temporary variable to make code more readable in patch 15
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 430 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 500c74db746c..d7c30d366935 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -5,6 +5,7 @@ CFLAGS =  -Wall -Wl,--no-as-needed -O2 -g
 CFLAGS += -I../../../../usr/include/
 
 TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh rtnetlink.sh
+TEST_PROGS += fib_tests.sh
 TEST_GEN_FILES =  socket
 TEST_GEN_FILES += psock_fanout psock_tpacket msg_zerocopy
 TEST_GEN_PROGS = reuseport_bpf reuseport_bpf_cpu reuseport_bpf_numa
diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh
new file mode 100755
index 000000000000..a9154eefb2e2
--- /dev/null
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -0,0 +1,429 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# This test is for checking IPv4 and IPv6 FIB behavior in response to
+# different events.
+
+ret=0
+
+check_err()
+{
+	if [ $ret -eq 0 ]; then
+		ret=$1
+	fi
+}
+
+check_fail()
+{
+	if [ $1 -eq 0 ]; then
+		ret=1
+	fi
+}
+
+netns_create()
+{
+	local testns=$1
+
+	ip netns add $testns
+	ip netns exec $testns ip link set dev lo up
+}
+
+fib_unreg_unicast_test()
+{
+	ret=0
+
+	netns_create "testns"
+
+	ip netns exec testns ip link add dummy0 type dummy
+	ip netns exec testns ip link set dev dummy0 up
+
+	ip netns exec testns ip address add 198.51.100.1/24 dev dummy0
+	ip netns exec testns ip -6 address add 2001:db8:1::1/64 dev dummy0
+
+	ip netns exec testns ip route get fibmatch 198.51.100.2 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::2 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip link del dev dummy0
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 198.51.100.2 &> /dev/null
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::2 &> /dev/null
+	check_fail $?
+
+	ip netns del testns
+
+	if [ $ret -ne 0 ]; then
+		echo "FAIL: unicast route test"
+		return 1
+	fi
+	echo "PASS: unicast route test"
+}
+
+fib_unreg_multipath_test()
+{
+	ret=0
+
+	netns_create "testns"
+
+	ip netns exec testns ip link add dummy0 type dummy
+	ip netns exec testns ip link set dev dummy0 up
+
+	ip netns exec testns ip link add dummy1 type dummy
+	ip netns exec testns ip link set dev dummy1 up
+
+	ip netns exec testns ip address add 198.51.100.1/24 dev dummy0
+	ip netns exec testns ip -6 address add 2001:db8:1::1/64 dev dummy0
+
+	ip netns exec testns ip address add 192.0.2.1/24 dev dummy1
+	ip netns exec testns ip -6 address add 2001:db8:2::1/64 dev dummy1
+
+	ip netns exec testns ip route add 203.0.113.0/24 \
+		nexthop via 198.51.100.2 dev dummy0 \
+		nexthop via 192.0.2.2 dev dummy1
+	ip netns exec testns ip -6 route add 2001:db8:3::/64 \
+		nexthop via 2001:db8:1::2 dev dummy0 \
+		nexthop via 2001:db8:2::2 dev dummy1
+
+	ip netns exec testns ip route get fibmatch 203.0.113.1 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:3::1 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip link del dev dummy0
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 203.0.113.1 &> /dev/null
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:3::1 &> /dev/null
+	# In IPv6 we do not flush the entire multipath route.
+	check_err $?
+
+	ip netns exec testns ip link del dev dummy1
+
+	ip netns del testns
+
+	if [ $ret -ne 0 ]; then
+		echo "FAIL: multipath route test"
+		return 1
+	fi
+	echo "PASS: multipath route test"
+}
+
+fib_unreg_test()
+{
+	echo "Running netdev unregister tests"
+
+	fib_unreg_unicast_test
+	fib_unreg_multipath_test
+}
+
+fib_down_unicast_test()
+{
+	ret=0
+
+	netns_create "testns"
+
+	ip netns exec testns ip link add dummy0 type dummy
+	ip netns exec testns ip link set dev dummy0 up
+
+	ip netns exec testns ip address add 198.51.100.1/24 dev dummy0
+	ip netns exec testns ip -6 address add 2001:db8:1::1/64 dev dummy0
+
+	ip netns exec testns ip route get fibmatch 198.51.100.2 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::2 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip link set dev dummy0 down
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 198.51.100.2 &> /dev/null
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::2 &> /dev/null
+	check_fail $?
+
+	ip netns exec testns ip link del dev dummy0
+
+	ip netns del testns
+
+	if [ $ret -ne 0 ]; then
+		echo "FAIL: unicast route test"
+		return 1
+	fi
+	echo "PASS: unicast route test"
+}
+
+fib_down_multipath_test_do()
+{
+	local down_dev=$1
+	local up_dev=$2
+
+	ip netns exec testns ip route get fibmatch 203.0.113.1 \
+		oif $down_dev &> /dev/null
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:3::1 \
+		oif $down_dev &> /dev/null
+	check_fail $?
+
+	ip netns exec testns ip route get fibmatch 203.0.113.1 \
+		oif $up_dev &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:3::1 \
+		oif $up_dev &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 203.0.113.1 | \
+		grep $down_dev | grep -q "dead linkdown"
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:3::1 | \
+		grep $down_dev | grep -q "dead linkdown"
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 203.0.113.1 | \
+		grep $up_dev | grep -q "dead linkdown"
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:3::1 | \
+		grep $up_dev | grep -q "dead linkdown"
+	check_fail $?
+}
+
+fib_down_multipath_test()
+{
+	ret=0
+
+	netns_create "testns"
+
+	ip netns exec testns ip link add dummy0 type dummy
+	ip netns exec testns ip link set dev dummy0 up
+
+	ip netns exec testns ip link add dummy1 type dummy
+	ip netns exec testns ip link set dev dummy1 up
+
+	ip netns exec testns ip address add 198.51.100.1/24 dev dummy0
+	ip netns exec testns ip -6 address add 2001:db8:1::1/64 dev dummy0
+
+	ip netns exec testns ip address add 192.0.2.1/24 dev dummy1
+	ip netns exec testns ip -6 address add 2001:db8:2::1/64 dev dummy1
+
+	ip netns exec testns ip route add 203.0.113.0/24 \
+		nexthop via 198.51.100.2 dev dummy0 \
+		nexthop via 192.0.2.2 dev dummy1
+	ip netns exec testns ip -6 route add 2001:db8:3::/64 \
+		nexthop via 2001:db8:1::2 dev dummy0 \
+		nexthop via 2001:db8:2::2 dev dummy1
+
+	ip netns exec testns ip route get fibmatch 203.0.113.1 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:3::1 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip link set dev dummy0 down
+	check_err $?
+
+	fib_down_multipath_test_do "dummy0" "dummy1"
+
+	ip netns exec testns ip link set dev dummy0 up
+	check_err $?
+	ip netns exec testns ip link set dev dummy1 down
+	check_err $?
+
+	fib_down_multipath_test_do "dummy1" "dummy0"
+
+	ip netns exec testns ip link set dev dummy0 down
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 203.0.113.1 &> /dev/null
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:3::1 &> /dev/null
+	check_fail $?
+
+	ip netns exec testns ip link del dev dummy1
+	ip netns exec testns ip link del dev dummy0
+
+	ip netns del testns
+
+	if [ $ret -ne 0 ]; then
+		echo "FAIL: multipath route test"
+		return 1
+	fi
+	echo "PASS: multipath route test"
+}
+
+fib_down_test()
+{
+	echo "Running netdev down tests"
+
+	fib_down_unicast_test
+	fib_down_multipath_test
+}
+
+fib_carrier_local_test()
+{
+	ret=0
+
+	# Local routes should not be affected when carrier changes.
+	netns_create "testns"
+
+	ip netns exec testns ip link add dummy0 type dummy
+	ip netns exec testns ip link set dev dummy0 up
+
+	ip netns exec testns ip link set dev dummy0 carrier on
+
+	ip netns exec testns ip address add 198.51.100.1/24 dev dummy0
+	ip netns exec testns ip -6 address add 2001:db8:1::1/64 dev dummy0
+
+	ip netns exec testns ip route get fibmatch 198.51.100.1 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::1 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 198.51.100.1 | \
+		grep -q "linkdown"
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::1 | \
+		grep -q "linkdown"
+	check_fail $?
+
+	ip netns exec testns ip link set dev dummy0 carrier off
+
+	ip netns exec testns ip route get fibmatch 198.51.100.1 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::1 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 198.51.100.1 | \
+		grep -q "linkdown"
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::1 | \
+		grep -q "linkdown"
+	check_fail $?
+
+	ip netns exec testns ip address add 192.0.2.1/24 dev dummy0
+	ip netns exec testns ip -6 address add 2001:db8:2::1/64 dev dummy0
+
+	ip netns exec testns ip route get fibmatch 192.0.2.1 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:2::1 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 192.0.2.1 | \
+		grep -q "linkdown"
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:2::1 | \
+		grep -q "linkdown"
+	check_fail $?
+
+	ip netns exec testns ip link del dev dummy0
+
+	ip netns del testns
+
+	if [ $ret -ne 0 ]; then
+		echo "FAIL: local route carrier test"
+		return 1
+	fi
+	echo "PASS: local route carrier test"
+}
+
+fib_carrier_unicast_test()
+{
+	ret=0
+
+	netns_create "testns"
+
+	ip netns exec testns ip link add dummy0 type dummy
+	ip netns exec testns ip link set dev dummy0 up
+
+	ip netns exec testns ip link set dev dummy0 carrier on
+
+	ip netns exec testns ip address add 198.51.100.1/24 dev dummy0
+	ip netns exec testns ip -6 address add 2001:db8:1::1/64 dev dummy0
+
+	ip netns exec testns ip route get fibmatch 198.51.100.2 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::2 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 198.51.100.2 | \
+		grep -q "linkdown"
+	check_fail $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::2 | \
+		grep -q "linkdown"
+	check_fail $?
+
+	ip netns exec testns ip link set dev dummy0 carrier off
+
+	ip netns exec testns ip route get fibmatch 198.51.100.2 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::2 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 198.51.100.2 | \
+		grep -q "linkdown"
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:1::2 | \
+		grep -q "linkdown"
+	check_err $?
+
+	ip netns exec testns ip address add 192.0.2.1/24 dev dummy0
+	ip netns exec testns ip -6 address add 2001:db8:2::1/64 dev dummy0
+
+	ip netns exec testns ip route get fibmatch 192.0.2.2 &> /dev/null
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:2::2 &> /dev/null
+	check_err $?
+
+	ip netns exec testns ip route get fibmatch 192.0.2.2 | \
+		grep -q "linkdown"
+	check_err $?
+	ip netns exec testns ip -6 route get fibmatch 2001:db8:2::2 | \
+		grep -q "linkdown"
+	check_err $?
+
+	ip netns exec testns ip link del dev dummy0
+
+	ip netns del testns
+
+	if [ $ret -ne 0 ]; then
+		echo "FAIL: unicast route carrier test"
+		return 1
+	fi
+	echo "PASS: unicast route carrier test"
+}
+
+fib_carrier_test()
+{
+	echo "Running netdev carrier change tests"
+
+	fib_carrier_local_test
+	fib_carrier_unicast_test
+}
+
+fib_test()
+{
+	fib_unreg_test
+	fib_down_test
+	fib_carrier_test
+}
+
+if [ "$(id -u)" -ne 0 ];then
+	echo "SKIP: Need root privileges"
+	exit 0
+fi
+
+if [ ! -x "$(command -v ip)" ]; then
+	echo "SKIP: Could not run test without ip tool"
+	exit 0
+fi
+
+ip route help 2>&1 | grep -q fibmatch
+if [ $? -ne 0 ]; then
+	echo "SKIP: iproute2 too old, missing fibmatch"
+	exit 0
+fi
+
+fib_test
+
+exit $ret