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唐小鸭
d20476a66c
SSE-C ciphertext passthrough replicates via X-Rustfs-Replication-* transport
headers. A MinIO/generic-S3 target silently discards them, storing bare
ciphertext with no decryption material — yet the PUT succeeded, so the object
reported COMPLETED with a silently unreadable replica (backlog#1675 N2).
Fail-closed design:
- SsecPassthroughCapability {Unknown, Supported, Unsupported} cached in
BucketTargetSys per target ARN with a recording timestamp. Entries reset
whenever the target is rebuilt, edited, or removed (arn_remotes_map
lifecycle) and expire after SSEC_PASSTHROUGH_CAPABILITY_TTL (10 minutes):
an expired verdict in either direction is re-earned through the audit, so
an Unsupported target recovers automatically after an upgrade (at most one
wasted PUT+HEAD audit per bad target per TTL window) and a Supported
verdict cannot outlive a backend swapped behind the same endpoint.
- Replication worker (replicate_object and replicate_all): fresh Unsupported
targets never receive the PUT — the attempt fails immediately into the
normal MRF retry channel with a "run ?replication-check to re-probe" hint.
Unknown or expired verdicts are audited: after the PUT the worker HEADs
the replica back through the replication-check channel (source version id
mapped through resolve_read_api_version_id, so null-version objects audit
correctly) and requires SSE-C evidence (the echoed customer-algorithm
header); missing evidence records Unsupported and fails the attempt.
Convergence HEADs are audited the same way, so a broken ciphertext replica
from an earlier attempt can never launder itself into COMPLETED via an
ETag match. The gate/evidence policy is pure (replication_target_boundary,
staleness folded in as an input) for the M2 worker migration.
- replication-check grows an SsecPassthrough probe phase: a probe PUT
carrying the live transport-header shape, HEAD-back for evidence, and a
machine-readable Code BucketRemoteSsecPassthroughUnsupported on failure.
The probe verdict is synced into the runtime capability cache. Unlike
VersionFidelity, a failed SsecPassthrough phase does NOT fail the target
overall — it is a capability limit, not a broken replication contract,
and a plaintext-only deployment against such a target must not turn red.
- fake_s3_target: default mode now models a RustFS target (stores the
transport headers, echoes SSE-C evidence); the new
drop_unlisted_replication_headers mode models MinIO. The journal records
whether a request carried transport headers.
Receiver-echo verification: the replication-check HEAD exemption only skips
SSE-C key validation; the response has always built sse-customer-algorithm
from stored metadata (rustfs/src/app/object_usecase.rs), so no receiver
change was needed — pinned end to end by the replication-check e2e against
a real RustFS target.
Rolling-upgrade constraint: RustFS targets older than the replication-check
HEAD exemption (#5898) answer the audit HEAD without SSE-C evidence (or fail
it outright), so SSE-C replication to such targets reports FAILED. This is
deliberate — FAILED-and-retryable beats a silently undecryptable replica —
and self-heals: once the target is upgraded, the next TTL expiry (or a
manual ?replication-check re-probe) re-audits and records Supported.
Plaintext and managed-SSE replication are unaffected. The capability cache
is per-node; each node audits independently.
Known limitations:
- The audit judges evidence from the echoed customer-algorithm header only.
A hypothetical target that preserves that one header while dropping other
transport headers (partial-drop) would pass the audit; no known target
behaves this way — observed targets drop the whole unknown-header family.
- A mixed-version target cluster can flap the verdict between audits routed
to different target nodes until the rollout completes; the TTL bounds how
long each stale verdict persists.
New e2e (backlog#1675 C1 + N2, red-first): fail-closed against a
header-dropping fake (FAILED + no second PUT via the capability cache,
journal-asserted; red run showed the old COMPLETED), replication-check
reports the SsecPassthrough phase Code while the target stays OK overall,
SSE-C heal convergence after a real target outage, and SSE-C
existing-object resync landing a REPLICA readable with the customer key.
TTL expiry in both directions is pinned at the cache and gate seams.