a143cd065ba06e1a2bdc5143a19ec156e53650ef
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a143cd065b |
fix(transport): gate transport execution behind commissioning (review 635)
Addresses B1 and B2 from formal review 635 on PR #966. Both are one defect:
the seam conflated two questions that must stay separate.
recognition: "is this an identifier this system knows, and may it be
bound, pinned and recorded?"
execution: "is this entrypoint commissioned to actually serve on it?"
SUPPORTED_TRANSPORTS answered the first and was then used to answer the
second, so registering streamable-http was the same act as executing it.
With mcp.run fed the bound value, GITEA_MCP_TRANSPORT=streamable-http
reached FastMCP.run -> run_streamable_http_async and started a uvicorn
HTTP server over the whole tool surface with auth=None, no TLS and no
per-request principal. That endpoint is owned by #938 and is an explicit
non-goal of #931. B2 is why B1 was reachable: bound_transport was read
only by reporting sites, so no decision anywhere depended on it.
The fix adds an execution-authorization layer rather than removing the
identifier or mapping it to stdio, both of which would have destroyed the
seam #931 exists to create.
mcp_transport_config gains EXECUTABLE_TRANSPORTS, a strict subset of
SUPPORTED_TRANSPORTS containing only the local transport, plus
TRANSPORT_EXECUTION_OWNER recording that #938 commissions the remote
listener. assess_transport_execution returns a structured verdict:
transport, recognized, executable, allowed, blocker_kind, owner_issue,
reasons and exact_next_action.
mcp_daemon_guard gains assess_serve_authorization, which is the decision
that consumes bound_transport and is what stops it being reporting-only
metadata, and authorize_transport_execution, which enforces two ordered
boundaries: assert_transport_bound first, so an unbound runtime keeps its
pre-existing #695 failure and reason code; then execution authorization,
so a registered but uncommissioned transport is refused before any
listener exists and before any tool can dispatch. TransportExecutionError
subclasses UnsanctionedRuntimeError, so every existing fail-closed handler
still catches it while a caller that cares can distinguish the two cases.
native_runtime_status now reports executable_transports, serve_authorized
and the full serve_authorization verdict.
The entrypoint serves through authorize_transport_execution.
Net effect. stdio: unchanged, still binds and still reaches the runner.
streamable-http: still recognized, still validated, still pinned, still
recorded in decision-lock and audit provenance -- and refused at the serve
boundary with blocker transport_listener_not_commissioned naming #938.
Unregistered identifiers still fail earlier, at bind validation. Unbound
execution keeps the #695 contract. Rebind idempotence and conflict
rejection, session isolation, provenance and secret handling are untouched.
Tests: 63 in tests/test_issue_931_transport_bind_seam.py, up from 42. New
coverage proves stdio reaches the real runner; the remote identifier binds
and is recorded yet never reaches run(); no socket is bound during the
refusal, asserted with a socket.bind tripwire; the refusal names the
transport, the unmet requirement and #938; the decision genuinely consumes
bound_transport, proven by flipping only that value; no mutation is
authorized after denial; verdicts do not leak across runtimes; and the
refusal carries no credential material. Per review 635 the two file-list
scans are now globs over the production surface, and a new test asserts
there is exactly one mcp.run site and that it routes through the guard.
#956 anchors re-anchored for the two lines this change shifted,
mcp_daemon_guard.py 178->195 and 519->583. No other anchor moved.
Full suite from the branches/ worktree: 28 failed, 5864 passed, 6 skipped,
1047 subtests. Base
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2fb835a1aa |
docs(remote-mcp): stamp the commit the #956 anchors were re-derived at
The anchor fixture records the commit its anchors were taken at, and the threat model must state the same commit, so a reviewer can resolve every cited line at a named revision. Both still named |
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c162608175 |
feat(transport): add transport-neutral MCP bind seam
Closes #931.
The transport was a literal passed once at the bottom of the module,
bind_native_mcp_transport(transport="stdio"), and every guard that asks
"is this a trusted native session" resolves that question through the
value bound there. The string was a constant in the authorization chain
rather than configuration, so a remote transport had no way to be
expressed and no way to be told apart from an untrusted offline import.
mcp_transport_config becomes the single source of truth: it owns the
permitted set, the default, and the resolution of deployment
configuration (GITEA_MCP_TRANSPORT) into a validated identifier. Unset
configuration still yields stdio, so existing deployments are unchanged.
streamable-http is accepted so the bind is pluggable; standing up its
listener remains #938. sse is deliberately not registered.
bind_native_mcp_transport now resolves from configuration when no
transport argument is given, validates against that one permitted set
before writing the runtime record, and pins the result. bound_transport
is the shared accessor every transport-aware guard reads; it reports the
pinned value and never the environment, so a post-bind GITEA_MCP_TRANSPORT
change cannot move what a guard observes -- the rule already applied to
the session-state root under #695 AC2. Rebinding the same identifier is
idempotent; rebinding a different one is refused, so two guards can never
disagree within one process. assert_transport_bound fails closed before
mcp.run, so an absent or invalid bind stops the server instead of serving
tools over a transport no guard can name.
The bound identifier is now recorded in durable provenance:
mutation_provenance_fields gains bound_transport, which reaches the
decision lock through mcp_session_state.save_state and the audit records
that already spread those fields. The pre-existing transport field keeps
its trust-class values, so no durable record changes shape.
assess_transport_for_auth_mint reports the bound transport through the
same accessor; its verdict is unchanged.
#956's anchor fixture and threat model are re-anchored for the lines this
change shifts, and the two boundary claims that #931 makes false -- the
"literal stdio bind" in B1 and the stdio contract at mcp_server.py:4 --
are restated. Without this the #956 guard fails, which is what it is for.
Non-goals, untouched: the remote listener (#938), per-request principal
resolution (#932), client-managed provenance policy (#934), TLS and
remote client authentication, role capability sets, repository-binding
semantics.
Tests: tests/test_issue_931_transport_bind_seam.py, 42 tests, covering
default bind, explicit stdio, the accepted non-stdio identifier, an
unregistered identifier, no bind at all, one-value agreement across
guards, post-bind environment tampering, the durable decision-lock
record, the rebind contract, and the #695 protections that must not
regress.
Full suite from the branches/ worktree: 28 failed, 5843 passed, 6
skipped, 1047 subtests. The pinned base
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b3de9c941c |
docs(remote-mcp): threat model, trust boundaries, and decomposition ruling (Closes #956)
#930 inventoried stdio coupling; nothing stated what the adversary is, what each boundary protects, or why one process may hold credentials for several services. This adds that document as child 2 of epic #929. Adds docs/remote-mcp/threat-model.md covering 10 assets, the 5 adversaries #956 names, 9 trust boundaries, the data flows between them, a 14-entry per-boundary credential inventory, and an explicit decomposition ruling. Findings established from live native evidence at this commit: - Four prgs roles (reviewer, merger, reconciler, controller) resolve to one Gitea account, so separation of duty between approving and landing is enforced only by which process a call reaches. The mdcps tenant has no role separation at all: author, reviewer, and merger share one account. - Any one role process can resolve every other role's credential. gitea_list_profiles reports "credentials present" for other roles because it calls resolve_token on each one. - The Gitea server reads Jenkins and GlitchTip secrets out of the keychain to produce the "authenticated" word in gitea_audit_config's service summaries. - Jenkins and GlitchTip were already decomposed into separate MCP servers; the credential references were left behind in the Gitea configuration. Ruling D1 forbids a single integration process from holding credentials for unrelated services, with one time-boxed dual-run exception for the local fleet that expires with #939. D2 requires separation of duty to be credential-backed, D3 scopes credential resolution to the request principal, and D4 gives coordination state its own authority. Every #929 child from 2 through 10 is mapped to the boundary it implements. Anchors are enforced rather than asserted. #930's inventory anchors into gitea_mcp_server.py had already drifted between |