selftests/net: convert srv6_end_dt46_l3vpn_test.sh to run it in unique namespace

As the name \${rt-${rt}} may make reader confuse, convert the variable
hs/rt in setup_rt/hs to hid, rid. Here is the test result after conversion.

]# ./srv6_end_dt46_l3vpn_test.sh

################################################################################
TEST SECTION: IPv6 routers connectivity test
################################################################################

TEST: Routers connectivity: rt-1 -> rt-2 [ OK ]

TEST: Routers connectivity: rt-2 -> rt-1 [ OK ]

...

TEST: IPv4 Hosts isolation: hs-t200-4 -X-> hs-t100-2 [ OK ]

Tests passed: 34
Tests failed: 0

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20231213060856.4030084-3-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: srv6: make srv6_end_dt46_l3vpn_test more robust

On some distributions, the rp_filter is automatically set (=1) by
default on a netdev basis (also on VRFs).
In an SRv6 End.DT46 behavior, decapsulated IPv4 packets are routed using
the table associated with the VRF bound to that tunnel. During lookup
operations, the rp_filter can lead to packet loss when activated on the
VRF.
Therefore, we chose to make this selftest more robust by explicitly
disabling the rp_filter during tests (as it is automatically set by some
Linux distributions).

Fixes: 03a0b567a03d ("selftests: seg6: add selftest for SRv6 End.DT46 Behavior")
Reported-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Tested-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests/net: Use kselftest skip code for skipped tests

There are several test cases in the net directory are still using
exit 0 or exit 1 when they need to be skipped. Use kselftest
framework skip code instead so it can help us to distinguish the
return status.

Criterion to filter out what should be fixed in net directory:
grep -r "exit [01]" -B1 | grep -i skip

This change might cause some false-positives if people are running
these test scripts directly and only checking their return codes,
which will change from 0 to 4. However I think the impact should be
small as most of our scripts here are already using this skip code.
And there will be no such issue if running them with the kselftest
framework.

Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/20210823085854.40216-1-po-hsu.lin@canonical.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: seg6: add selftest for SRv6 End.DT46 Behavior

this selftest is designed for evaluating the new SRv6 End.DT46 Behavior
used, in this example, for implementing IPv4/IPv6 L3 VPN use cases.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Paolo Lungaroni <paolo.lungaroni@uniroma2.it>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>