bpf: Hoist type checking for nullable arg types

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check_func_arg has a plethora of weird if statements with empty branches.
They work around the fact that *_OR_NULL argument types should accept a
SCALAR_VALUE register, as long as it's value is 0. These statements make
it difficult to reason about the type checking logic.

Instead, skip more detailed type checking logic iff the register is 0,
and the function expects a nullable type. This allows simplifying the type
checking itself.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200921121227.255763-11-lmb@cloudflare.com

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Lorenz Bauer 2020-09-21 13:12:26 +01:00 • committed by Alexei Starovoitov

parent c18f0b6aee

commit fd1b0d604c

1 changed files with 30 additions and 34 deletions

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kernel/bpf/verifier.c

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