Adds the ReadFailed scenario (binary path resolves to a directory so
exists() succeeds but read() fails) and a scenarios coverage map at the
top of the test module. The map links each test to the audit fix
scenarios:
- valid CID, content matches: Allowed
- valid CID at admission, tampered content at execution: ContentMismatch
- missing binary where directory exists: Denied (sanity preserved)
- binary present but unreadable: ReadFailed (fail-closed)
Plus the existing sentinels for ungoverned-CID and corpus-not-mounted.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Tyler J King <tking@guildhouse.dev>
corpus_check() previously returned Allowed as soon as it found a file by
name in the corpus directory keyed by CID. The CID acted as a directory
label, not a content commitment. An attacker with write access to the
corpus directory could plant a malicious binary under a legitimate CID
and it would execute with that CID's authorization.
This change hashes the binary at the resolved path and compares to the
CID its directory is named for. Mismatches return a new ContentMismatch
variant; unreadable binaries return ReadFailed. Both are execution-denied
states — main.rs handles each explicitly with exit code 3 (previously
used only for Denied).
Both error classes emit Chronicle-shaped structured tracing events
(target: "chronicle") with stable event_type constants from
libgsh::chronicle_events. The field shape matches what substrate-chronicle's
post-io_uring emission API is expected to require; migration to direct
Chronicle emission becomes a mechanical translation once that API
stabilizes.
The tamper signal is that the binary and its directory name disagree.
This closes the execution-path half of the CID-content verification
audit fix — admission (corpus-operator) rejects CID forgery before the
enforcement ConfigMap is written; execution (libgsh) rejects any tamper
that landed after admission. Defense in depth across both layers.
Kernel-layer CID verification (the third layer, where eBPF LSM hooks
authorize by binary name via FNV-1a hash of comm) is explicit backlog,
deferred to Bifrost where in-kernel hashing or a ring-buffer userspace
verifier can be evaluated properly.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Tyler J King <tking@guildhouse.dev>
- corpus_check_with_base(): accepts explicit base directory
- corpus_check(): still defaults to /opt/substrate/corpus
- Improved corpus test with actual Allowed/Denied assertions
- Updated bascule-dev.toml with [gsap] section and shell_command
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
