selftests: forwarding: Fix packet matching in mirroring selftests

In commit 6de6e46d27ef ("cls_flower: Fix inability to match GRE/IPIP
packets"), cls_flower was fixed to match an outer packet of a tunneled
packet as would be expected, rather than dissecting to the inner packet and
matching on that.

This fix uncovered several issues in packet matching in mirroring
selftests:

- in mirror_gre_bridge_1d_vlan.sh and mirror_gre_vlan_bridge_1q.sh, the
vlan_ethtype match is copied around as "ip", even as some of the tests
are running over ip6gretap. This is fixed by using an "ipv6" for
vlan_ethtype in the ip6gretap tests.

- in mirror_gre_changes.sh, a filter to count GRE packets is set up to
match TTL of 50. This used to trigger in the offloaded datapath, where
the envelope TTL was matched, but not in the software datapath, which
considered TTL of the inner packet. Now that both match consistently, all
the packets were double-counted. This is fixed by marking the filter as
skip_hw, leaving only the SW datapath component active.

Fixes: 6de6e46d27ef ("cls_flower: Fix inability to match GRE/IPIP packets")
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: forwarding: mirror_vlan: Change test description

The test description is displayed with the PASS/FAIL resolution after
the test is ran. There however already is one other test described
exactly like this, which makes it unclear which of the tests passed or
failed. Make the description unique.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: forwarding: mirror_vlan: Uninstall trap

Instead of installing a trap before tests run and uninstalling it after
they run, mirror_vlan.sh installs it twice due to a typo. Fix the typo.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: forwarding: mirror_lib: Move here do_test_span_vlan_dir_ips()

Move the function do_test_span_vlan_dir_ips() from mirror_vlan.sh test
to a library file mirror_lib.sh to allow reuse. Fill in other entry
points similar to other testing functions in mirror_lib.sh, they will be
useful in following patches.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: forwarding: lib: Move here vlan_capture_{, un}install()

Move vlan_capture_install() and vlan_capture_uninstall() from
mirror_vlan.sh test to lib.sh so that it can be reused in other tests.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: forwarding: Test mirror-to-vlan

Test for "tc action mirred egress mirror" that mirrors to a vlan device.
- test_vlan() tests that the packets get mirrored
- test_tagged_vlan() tests that the mirrored packets have correct inner
VLAN tag.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>