Merge branch 'ipv4-address-protocol'

Petr Machata says:

====================
net: Allow changing IPv4 address protocol

IPv4 and IPv6 addresses can be assigned a protocol value that indicates the
provenance of the IP address. The attribute is modeled after ip route
protocols, and essentially allows the administrator or userspace stack to
tag addresses in some way that makes sense to the actor in question.

When IP address protocol field was added in commit 47f0bd50 ("net: Add
new protocol attribute to IP addresses"), the semantics included the
ability to change the protocol for IPv6 addresses, but not for IPv4
addresses. It seems this was not deliberate, but rather by accident.

One particular use case is tagging the addresses differently depending on
whether the routing stack should advertise them or not. Without support for
protocol replacement, this can not be done.

In this patchset, extend IPv4 to allow changing the protocol defined at an
address (in patch #1). Then in patches #2 and #3 add selftest coverage for
ip address protocols.

Currently the kernel simply ignores the new value. Thus allowing the
replacement changes the observable behavior. However, since IPv6 already
behaves like this anyway, and since the feature as such is relatively new,
it seems like the change is safe to make.

An example session with the feature in action:

	bash-5.2# ip address add dev d 192.0.2.1/28 proto 0xab
	bash-5.2# ip address show dev d
	4: d: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
	    link/ether 06:29:74:fd:1f:eb brd ff:ff:ff:ff:ff:ff
	    inet 192.0.2.1/28 scope global proto 0xab d
	       valid_lft forever preferred_lft forever

	bash-5.2# ip address replace dev d 192.0.2.1/28 proto 0x11
	bash-5.2# ip address show dev d
	4: d: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
	    link/ether 06:29:74:fd:1f:eb brd ff:ff:ff:ff:ff:ff
	    inet 192.0.2.1/28 scope global proto 0x11 d
	       valid_lft forever preferred_lft forever
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/devinet.c

@@ -962,6 +962,7 @@ static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
 					 extack);
 	} else {
 		u32 new_metric = ifa->ifa_rt_priority;
+		u8 new_proto = ifa->ifa_proto;
 
 		inet_free_ifa(ifa);
 
@@ -975,6 +976,8 @@ static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
 			ifa->ifa_rt_priority = new_metric;
 		}
 
+		ifa->ifa_proto = new_proto;
+
 		set_ifa_lifetime(ifa, valid_lft, prefered_lft);
 		cancel_delayed_work(&check_lifetime_work);
 		queue_delayed_work(system_power_efficient_wq,

tools/testing/selftests/net/rtnetlink.sh

@@ -4,6 +4,31 @@
 #
 # set -e
 
+ALL_TESTS="
+	kci_test_polrouting
+	kci_test_route_get
+	kci_test_addrlft
+	kci_test_promote_secondaries
+	kci_test_tc
+	kci_test_gre
+	kci_test_gretap
+	kci_test_ip6gretap
+	kci_test_erspan
+	kci_test_ip6erspan
+	kci_test_bridge
+	kci_test_addrlabel
+	kci_test_ifalias
+	kci_test_vrf
+	kci_test_encap
+	kci_test_macsec
+	kci_test_ipsec
+	kci_test_ipsec_offload
+	kci_test_fdb_get
+	kci_test_neigh_get
+	kci_test_bridge_parent_id
+	kci_test_address_proto
+"
+
 devdummy="test-dummy0"
 
 # Kselftest framework requirement - SKIP code is 4.
@@ -1225,62 +1250,126 @@ kci_test_bridge_parent_id()
 	echo "PASS: bridge_parent_id"
 }
 
-kci_test_rtnl()
+address_get_proto()
 {
+	local addr=$1; shift
+
+	ip -N -j address show dev "$devdummy" |
+	    jq -e -r --arg addr "${addr%/*}" \
+	       '.[].addr_info[] | select(.local == $addr) | .protocol'
+}
+
+address_count()
+{
+	ip -N -j address show dev "$devdummy" "$@" |
+	    jq -e -r '[.[].addr_info[] | .local | select(. != null)] | length'
+}
+
+do_test_address_proto()
+{
+	local what=$1; shift
+	local addr=$1; shift
+	local addr2=${addr%/*}2/${addr#*/}
+	local addr3=${addr%/*}3/${addr#*/}
+	local proto
+	local count
 	local ret=0
-	kci_add_dummy
-	if [ $ret -ne 0 ];then
-		echo "FAIL: cannot add dummy interface"
-		return 1
-	fi
+	local err
 
-	kci_test_polrouting
+	ip address add dev "$devdummy" "$addr3"
 	check_err $?
-	kci_test_route_get
-	check_err $?
-	kci_test_addrlft
+	proto=$(address_get_proto "$addr3")
+	[[ "$proto" == null ]]
 	check_err $?
-	kci_test_promote_secondaries
-	check_err $?
-	kci_test_tc
-	check_err $?
-	kci_test_gre
-	check_err $?
-	kci_test_gretap
-	check_err $?
-	kci_test_ip6gretap
-	check_err $?
-	kci_test_erspan
+
+	ip address add dev "$devdummy" "$addr2" proto 0x99
 	check_err $?
-	kci_test_ip6erspan
+	proto=$(address_get_proto "$addr2")
+	[[ "$proto" == 0x99 ]]
 	check_err $?
-	kci_test_bridge
+
+	ip address add dev "$devdummy" "$addr" proto 0xab
 	check_err $?
-	kci_test_addrlabel
+	proto=$(address_get_proto "$addr")
+	[[ "$proto" == 0xab ]]
 	check_err $?
-	kci_test_ifalias
+
+	ip address replace dev "$devdummy" "$addr" proto 0x11
+	proto=$(address_get_proto "$addr")
 	check_err $?
-	kci_test_vrf
+	[[ "$proto" == 0x11 ]]
 	check_err $?
-	kci_test_encap
+
+	count=$(address_count)
 	check_err $?
-	kci_test_macsec
+	(( count == 3 )) # $addr, $addr2 and $addr3
+
+	count=$(address_count proto 0)
 	check_err $?
-	kci_test_ipsec
+	(( count == 1 )) # just $addr2
+
+	count=$(address_count proto 0x11)
 	check_err $?
-	kci_test_ipsec_offload
+	(( count == 2 )) # $addr and $addr2
+
+	count=$(address_count proto 0xab)
 	check_err $?
-	kci_test_fdb_get
+	(( count == 1 )) # just $addr2
+
+	ip address del dev "$devdummy" "$addr"
+	ip address del dev "$devdummy" "$addr2"
+	ip address del dev "$devdummy" "$addr3"
+
+	if [ $ret -ne 0 ]; then
+		echo "FAIL: address proto $what"
+		return 1
+	fi
+	echo "PASS: address proto $what"
+}
+
+kci_test_address_proto()
+{
+	local ret=0
+
+	do_test_address_proto IPv4 192.0.2.1/28
 	check_err $?
-	kci_test_neigh_get
+
+	do_test_address_proto IPv6 2001:db8:1::1/64
 	check_err $?
-	kci_test_bridge_parent_id
+
+	return $ret
+}
+
+kci_test_rtnl()
+{
+	local current_test
+	local ret=0
+
+	kci_add_dummy
+	if [ $ret -ne 0 ];then
+		echo "FAIL: cannot add dummy interface"
+		return 1
+	fi
+
+	for current_test in ${TESTS:-$ALL_TESTS}; do
+		$current_test
 		check_err $?
+	done
 
 	kci_del_dummy
 	return $ret
 }
 
+usage()
+{
+	cat <<EOF
+usage: ${0##*/} OPTS
+
+        -t <test>   Test(s) to run (default: all)
+                    (options: $(echo $ALL_TESTS))
+EOF
+}
+
 #check for needed privileges
 if [ "$(id -u)" -ne 0 ];then
 	echo "SKIP: Need root privileges"
@@ -1295,6 +1384,14 @@ for x in ip tc;do
 	fi
 done
 
+while getopts t:h o; do
+	case $o in
+		t) TESTS=$OPTARG;;
+		h) usage; exit 0;;
+		*) usage; exit 1;;
+	esac
+done
+
 kci_test_rtnl
 
 exit $?