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

Here is the test result after conversion.

# ./icmp_redirect.sh

###########################################################################
Legacy routing
###########################################################################

TEST: IPv4: redirect exception [ OK ]

...

TEST: IPv4: mtu exception plus redirect [ OK ]
TEST: IPv6: mtu exception plus redirect [ OK ]

Tests passed: 40
Tests failed: 0
Tests xfailed: 0

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

selftests: icmp_redirect: pass xfail=0 to log_test()

If any sub-test in this icmp_redirect.sh is failing but not expected
to fail. The script will complain:
./icmp_redirect.sh: line 72: [: 1: unary operator expected

This is because when the sub-test is not expected to fail, we won't
pass any value for the xfail local variable in log_test() and thus
it's empty. Fix this by passing 0 as the 4th variable to log_test()
for non-xfail cases.

v2: added fixes tag

Fixes: 0a36a75c6818 ("selftests: icmp_redirect: support expected failures")
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: icmp_redirect: IPv6 PMTU info should be cleared after redirect

After redirecting, it's already a new path. So the old PMTU info should
be cleared. The IPv6 test "mtu exception plus redirect" should only
has redirect info without old PMTU.

The IPv4 test can not be changed because of legacy.

Fixes: ec8105352869 ("selftests: Add redirect tests")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: icmp_redirect: remove from checking for IPv6 route get

If the kernel doesn't enable option CONFIG_IPV6_SUBTREES, the RTA_SRC
info will not be exported to userspace in rt6_fill_node(). And ip cmd will
not print "from ::" to the route output. So remove this check.

Fixes: ec8105352869 ("selftests: Add redirect tests")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: icmp_redirect: support expected failures

According to a comment in commit 99513cfa16c6 ("selftest: Fixes for
icmp_redirect test") the test "IPv6: mtu exception plus redirect" is
expected to fail, because of a bug in the IPv6 logic that hasn't been
fixed yet apparently.

We should probably consider this failure as an "expected failure",
therefore change the script to return XFAIL for that particular test and
also report the total amount of expected failures at the end of the run.

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: disable rp_filter for icmp_redirect.sh

h1 is initially configured to reach h2 via r1 rather than the
more direct path through r2. If rp_filter is set and inherited
for r2, forwarding fails since the source address of h1 is
reachable from eth0 vs the packet coming to it via r1 and eth1.
Since rp_filter setting affects the test, explicitly reset it.

Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: icmp_redirect: Add support for routing via nexthop objects

Add a second pass to icmp_redirect.sh to use nexthop objects for
routes.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftest: Fixes for icmp_redirect test

I was really surprised that the IPv6 mtu exception followed by redirect
test was passing as nothing about the code suggests it should. The problem
is actually with the logic in the test script.

Fix the test cases as follows:
1. add debug function to dump the initial and redirect gateway addresses
for ipv6. This is shown only in verbose mode. It helps verify the
output of 'route get'.

2. fix the check_exception logic for the reset case to make sure that
for IPv4 neither mtu nor redirect appears in the 'route get' output.
For IPv6, make sure mtu is not present and the gateway is the initial
R1 lladdr.

3. fix the reset logic by using a function to delete the routes added by
initial_route_*. This format works better for the nexthop version of
the tests.

While improving the test cases, go ahead and ensure that forwarding is
disabled since IPv6 redirect requires it.

Also, runs with kernel debugging enabled sometimes show a failure with
one of the ipv4 tests, so spread the pings over longer time interval.

The end result is that 2 tests now show failures:

TEST: IPv6: mtu exception plus redirect [FAIL]

and the VRF version.

This is a bug in the IPv6 logic that will need to be fixed
separately. Redirect followed by MTU works because __ip6_rt_update_pmtu
hits the 'if (!rt6_cache_allowed_for_pmtu(rt6))' path and updates the
mtu on the exception rt6_info.

MTU followed by redirect does not have this logic. rt6_do_redirect
creates a new exception and then rt6_insert_exception removes the old
one which has the MTU exception.

Fixes: ec8105352869 ("selftests: Add redirect tests")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: Add redirect tests

Add test for ICMP redirects and exception processing. Test is setup
for later addition of tests using nexthop objects for routing.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>