selftests/net: convert arp_ndisc_evict_nocarrier.sh to run it in unique namespace

Here is the test result after conversion.

]# ./arp_ndisc_evict_nocarrier.sh
run arp_evict_nocarrier=1 test
ok
run arp_evict_nocarrier=0 test
ok
run all.arp_evict_nocarrier=0 test
ok
run ndisc_evict_nocarrier=1 test
ok
run ndisc_evict_nocarrier=0 test
ok
run all.ndisc_evict_nocarrier=0 test
ok

Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

selftests: net: return non-zero for failures reported in arp_ndisc_evict_nocarrier

Return non-zero return value if there is any failure reported in this
script during the test. Otherwise it can only reflect the status of
the last command.

Fixes: f86ca07eb531 ("selftests: net: add arp_ndisc_evict_nocarrier")
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: net: fix cleanup_v6() for arp_ndisc_evict_nocarrier

The cleanup_v6() will cause the arp_ndisc_evict_nocarrier script exit
with 255 (No such file or directory), even the tests are good:

# selftests: net: arp_ndisc_evict_nocarrier.sh
# run arp_evict_nocarrier=1 test
# RTNETLINK answers: File exists
# ok
# run arp_evict_nocarrier=0 test
# RTNETLINK answers: File exists
# ok
# run all.arp_evict_nocarrier=0 test
# RTNETLINK answers: File exists
# ok
# run ndisc_evict_nocarrier=1 test
# ok
# run ndisc_evict_nocarrier=0 test
# ok
# run all.ndisc_evict_nocarrier=0 test
# ok
not ok 1 selftests: net: arp_ndisc_evict_nocarrier.sh # exit=255

This is because it's trying to modify the parameter for ipv4 instead.

Also, tests for ipv6 (run_ndisc_evict_nocarrier_enabled() and
run_ndisc_evict_nocarrier_disabled() are working on veth1, reflect
this fact in cleanup_v6().

Fixes: f86ca07eb531 ("selftests: net: add arp_ndisc_evict_nocarrier")
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: net: add arp_ndisc_evict_nocarrier

This tests the sysctl options for ARP/ND:

/net/ipv4/conf/<iface>/arp_evict_nocarrier
/net/ipv4/conf/all/arp_evict_nocarrier
/net/ipv6/conf/<iface>/ndisc_evict_nocarrier
/net/ipv6/conf/all/ndisc_evict_nocarrier

Signed-off-by: James Prestwood <prestwoj@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>