The "tampered arm64 binary is SIGKILLed (137)" premise is empirically false on
current macOS CI runners for an ad-hoc-signed CLI binary -- the binary has no
CS_KILL/hardened-runtime flag, so a tampered code page is not killed: it
executes the garbage and crashes with SIGILL (exit 132, run 28365724001), not
137. (remove-signature and corrupt-blob both ad-hoc re-sign on exec and run to
exit 0.) So no runtime exit code is a deterministic guard here, and
"tamper -> crash" is near-tautological (zeroed code crashes regardless of
signing).
Assert the real, deterministic integrity invariant instead: `codesign
--verify` REJECTS a tampered copy (the CodeDirectory page hashes no longer
match the modified code), while the untampered binary verifies cleanly (10a).
It is a pure userspace hash check -- no tampered code is executed. The copy is
separate, so the original binary stays intact for the 10e re-sign test.
Refs: github.com/garrytan/gstack#997, github.com/nodejs/node#40827
Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>
Martin Vogel
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