selftests/bpf: Add test for bpf_skb_change_tail on csum partial skbs

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Add a test which builds an ICMP error out of a TCP segment. A tcx prog
on the client's egress side trims the first data segment down to the
target size and pushes the ICMP error headers in front of it to then
reflect the packet back to the sender.

  # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t tc_change_tail
  [...]
  #509     tc_change_tail:OK
  #510     tc_change_tail_pmtu:OK
  Summary: 2/0 PASSED, 0 SKIPPED, 0/0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260907121025.1923656-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

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Daniel Borkmann 2026-09-07 14:10:25 +02:00 • committed by Alexei Starovoitov

parent 3b55f350c6

commit 15e2565f1c

2 changed files with 254 additions and 0 deletions

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125

tools/testing/selftests/bpf/prog_tests/tc_change_tail_pmtu.c

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129

tools/testing/selftests/bpf/progs/test_tc_change_tail_pmtu.c

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