bpf: Add selftests to cover packet access corner cases
This commit adds BPF verifier selftests that cover all corner cases by
packet boundary checks. Specifically, 8-byte packet reads are tested at
the beginning of data and at the beginning of data_meta, using all kinds
of boundary checks (all comparison operators: <, >, <=, >=; both
permutations of operands: data + length compared to end, end compared to
data + length). For each case there are three tests:
1. Length is just enough for an 8-byte read. Length is either 7 or 8,
depending on the comparison.
2. Length is increased by 1 - should still pass the verifier. These
cases are useful, because they failed before commit 2fa7d94afc1a
("bpf: Fix the off-by-two error in range markings").
3. Length is decreased by 1 - should be rejected by the verifier.
Some existing tests are just renamed to avoid duplication.
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211207081521.41923-1-maximmi@nvidia.com
1 file changed
