[SRU][J/N][PATCH 0/2] Set rp_filter to 0 during kselftest/net/pmtu.sh test

[Ian Whitfield]

BugLink: https://bugs.launchpad.net/bugs/2055473

[Impact]

During ubuntu_kselftests_net/net:pmtu.sh on 5.15 and 6.8 kernels, if the network
interface in use has rp_filter=1, 4 test cases fail unexpectedly:

# TEST: ICMPv4 with DSCP and ECN: PMTU exceptions [FAIL]
# PMTU exception wasn't created after exceeding MTU
# TEST: ICMPv4 with DSCP and ECN: PMTU exceptions - nexthop objects [FAIL]
# PMTU exception wasn't created after exceeding MTU
# TEST: UDPv4 with DSCP and ECN: PMTU exceptions [FAIL]
# PMTU exception wasn't created after exceeding MTU
# TEST: UDPv4 with DSCP and ECN: PMTU exceptions - nexthop objects [FAIL]
# PMTU exception wasn't created after exceeding MTU

This happens because the exception is being filtered by the strict rp_filter
setting, so the test believes one was not received. Because this is dependent
on the test environment's configuration, this failure would only happen on some
clouds, particularly GCE. Clouds which set rp_filter=2 (loose) are not affected.

This issue was fixed upstream by always disabling rp_filter during the test,
to improve consistency. With this upstream fix, 7.0 kernels are unaffected.
The affected tests were added after 5.4 so kernels earlier than 5.15 are also
unaffected.

[Fix]

Backport the fix commit:
ce17831f8e970 ("selftests: net: disable rp_filter after namespace initialization")
to 5.15 and 6.8, as well as any needed dependencies.

Backport notes in the commits should explain any conflict resolutions, but I
should particularly note that in jammy, net/lib.sh was added in our backport of
d83a580675927 ("selftests: net: use slowwait to stabilize vrf_route_leaking test")
by including some parts of
25ae948b44788 ("selftests/net: add lib.sh")
which we then finish backporting in this patchset.

[Test plan]

Ran the pmtu.sh ubuntu_kselftests_net test through autotest on jammy and noble,
then applied the patchsets to the kernel source and reran the tests. The failure
is resolved after applying. For jammy I also ran unicast_extensions.sh because
it was also touched during the backport.

[Where problems could occur]

All changes are within the selftests code, so problems should only show up as
invalid test results after applying the fix.

Hangbin Liu (5):
  selftests/net: add lib.sh
  selftests/net: add variable NS_LIST for lib.sh
  selftests/net: convert pmtu.sh to run it in unique namespace
  selftests: net: disable rp_filter after namespace initialization
  selftests/net: convert unicast_extensions.sh to run it in unique
    namespace

Yujie Liu (1):
  selftests/net: change shebang to bash to support "source"

 tools/testing/selftests/net/Makefile          |   2 +-
 tools/testing/selftests/net/forwarding/lib.sh |  27 +----
 tools/testing/selftests/net/lib.sh            |  69 ++++++++++++
 tools/testing/selftests/net/pmtu.sh           |  29 ++---
 .../selftests/net/unicast_extensions.sh       | 101 ++++++++----------
 5 files changed, 128 insertions(+), 100 deletions(-)

-- 
2.43.0