** Description changed:
+ SRU Justification
+
+ [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.
+
+ ---- ORIGINAL BUG REPORT ----
+
Issue found on J-gcp-6.5.0-1015.15~22.04.1 and M-gcp-6.5.0-1015.15 in
cycle sru-20240205
And can be reproduced with generic kernel on GCP cloud.
This is not a regression but something emerges after the pmtu.sh result
parsing logic update, which landed via stable update in sru-20240205
cycle (bug 2043198)
Dive into test history, we can see this failure all the way back to
sru-20231030 with M-6.5.0-1010.10 on GCP cloud.
19:48:21 DEBUG| [stdout] # selftests: net: pmtu.sh
19:48:21 DEBUG| [stdout] # TEST: ipv4: PMTU exceptions
[ OK ]
19:48:21 DEBUG| [stdout] # TEST: ipv4: PMTU exceptions - nexthop objects
[ OK ]
19:48:22 DEBUG| [stdout] # TEST: ipv6: PMTU exceptions
[ OK ]
19:48:22 DEBUG| [stdout] # TEST: ipv6: PMTU exceptions - nexthop objects
[ OK ]
19:48:23 DEBUG| [stdout] # TEST: ICMPv4 with DSCP and ECN: PMTU exceptions
[FAIL]
19:48:23 DEBUG| [stdout] # PMTU exception wasn't created after exceeding MTU
19:48:24 DEBUG| [stdout] # TEST: ICMPv4 with DSCP and ECN: PMTU exceptions -
nexthop objects [FAIL]
19:48:24 DEBUG| [stdout] # PMTU exception wasn't created after exceeding MTU
19:48:25 DEBUG| [stdout] # TEST: UDPv4 with DSCP and ECN: PMTU exceptions
[FAIL]
19:48:25 DEBUG| [stdout] # PMTU exception wasn't created after exceeding MTU
19:48:25 DEBUG| [stdout] # TEST: UDPv4 with DSCP and ECN: PMTU exceptions -
nexthop objects [FAIL]
19:48:25 DEBUG| [stdout] # PMTU exception wasn't created after exceeding MTU
....
Logfile also attached (rt.log)
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https://bugs.launchpad.net/bugs/2055473
Title:
pmtu.sh net selftest fail with PMTU exception wasn't created after
exceeding MTU
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