samples/bpf: ensure ipv6 is enabled before running tests

Currently, a few of BPF tests use ipv6 functionality. The problem here
is that if ipv6 is disabled, these tests will fail, and even if the
test fails, it will not tell you why it failed.

    $ sudo ./test_cgrp2_sock2.sh
    RTNETLINK answers: Permission denied

In order to fix this, this commit ensures ipv6 is enabled prior to
running tests.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Link: https://lore.kernel.org/r/20230115071613.125791-2-danieltimlee@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf/tc_l2_redirect.sh

@@ -8,6 +8,7 @@ REDIRECT_USER='./tc_l2_redirect'
 REDIRECT_BPF='./tc_l2_redirect_kern.o'
 
 RP_FILTER=$(< /proc/sys/net/ipv4/conf/all/rp_filter)
+IPV6_DISABLED=$(< /proc/sys/net/ipv6/conf/all/disable_ipv6)
 IPV6_FORWARDING=$(< /proc/sys/net/ipv6/conf/all/forwarding)
 
 function config_common {
@@ -64,6 +65,7 @@ function config_common {
 
 	sysctl -q -w net.ipv4.conf.all.rp_filter=0
 	sysctl -q -w net.ipv6.conf.all.forwarding=1
+	sysctl -q -w net.ipv6.conf.all.disable_ipv6=0
 }
 
 function cleanup {
@@ -77,6 +79,7 @@ function cleanup {
 	$IP link del ip6t >& /dev/null
 	sysctl -q -w net.ipv4.conf.all.rp_filter=$RP_FILTER
 	sysctl -q -w net.ipv6.conf.all.forwarding=$IPV6_FORWARDING
+	sysctl -q -w net.ipv6.conf.all.disable_ipv6=$IPV6_DISABLED
 	rm -f /sys/fs/bpf/tc/globals/tun_iface
 	[[ -z $DEBUG ]] || set -x
 	set -e

samples/bpf/test_cgrp2_sock2.sh

@@ -7,13 +7,15 @@ LINK_PIN=$BPFFS/test_cgrp2_sock2
 function config_device {
 	ip netns add at_ns0
 	ip link add veth0 type veth peer name veth0b
-	ip link set veth0b up
 	ip link set veth0 netns at_ns0
+	ip netns exec at_ns0 sysctl -q net.ipv6.conf.veth0.disable_ipv6=0
 	ip netns exec at_ns0 ip addr add 172.16.1.100/24 dev veth0
 	ip netns exec at_ns0 ip addr add 2401:db00::1/64 dev veth0 nodad
 	ip netns exec at_ns0 ip link set dev veth0 up
+	sysctl -q net.ipv6.conf.veth0b.disable_ipv6=0
 	ip addr add 172.16.1.101/24 dev veth0b
 	ip addr add 2401:db00::2/64 dev veth0b nodad
+	ip link set veth0b up
 }
 
 function config_cgroup {

samples/bpf/test_cgrp2_tc.sh

@@ -73,11 +73,13 @@ setup_net() {
 	start)
 	    $IP link add $HOST_IFC type veth peer name $NS_IFC || return $?
 	    $IP link set dev $HOST_IFC up || return $?
+	    sysctl -q net.ipv6.conf.$HOST_IFC.disable_ipv6=0
 	    sysctl -q net.ipv6.conf.$HOST_IFC.accept_dad=0
 
 	    $IP netns add ns || return $?
 	    $IP link set dev $NS_IFC netns ns || return $?
 	    $IP -n $NS link set dev $NS_IFC up || return $?
+	    $IP netns exec $NS sysctl -q net.ipv6.conf.$NS_IFC.disable_ipv6=0
 	    $IP netns exec $NS sysctl -q net.ipv6.conf.$NS_IFC.accept_dad=0
 	    $TC qdisc add dev $HOST_IFC clsact || return $?
 	    $TC filter add dev $HOST_IFC egress bpf da obj $BPF_PROG sec $BPF_SECTION || return $?