feat(core): support argument constraints on permission overrides - #896
feat(core): support argument constraints on permission overrides#896thisisanubhav wants to merge 24 commits into
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Endpoint overrides answered "may the agent call messages.post at all?".
Real authorization needs "may it call it with these arguments?" — posting
to #general without approval while an external DM still escalates.
Widen the overrides value from PermissionPolicy to a union: either a flat
policy as before, or { policy, constraints, otherwise? }. Existing configs
keep compiling and behave identically; constraints are opt-in.
Constraints map dot-notation argument paths to a condition — match (regex),
equals, in, notIn. Evaluation happens in evaluatePermission, ahead of any
database work in enforcePermission, so a constraint-allowed call creates no
approval record rather than creating one and resolving it.
Rules fail closed. A constraint is unsatisfied when the argument is absent,
is the wrong type for the operator, the regex is malformed, or the
constraints map is empty — the last because {} reading as "matches
everything" would silently apply the loosened policy to every call. When
constraints do not hold the override contributes `otherwise`, or nothing,
leaving the mode matrix to decide.
Closes corsairdev#283
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Included review availability: Your plan provides up to 10 included reviews per hour; 5 remain after this review. 📝 WalkthroughWalkthroughAdded conditional permission overrides based on endpoint arguments. Constraints support nested paths, regex matching, equality, inclusion, and exclusion. Matching policies apply directly. Non-matching policies use ChangesConditional permission overrides
Estimated code review effort: 3 (Moderate) | ~25 minutes Merge Risk: 🔵 Low · up to The change adds configurable regular-expression constraints to permission checks; pathological patterns could cause excessive backtracking on agent-controlled input and temporarily block request handling. The PR is mergeable with explicit owner awareness or follow-up on regex safety. Sequence Diagram(s)sequenceDiagram
participant Caller
participant enforcePermission
participant evaluatePermission
participant resolveOverridePolicy
Caller->>enforcePermission: endpoint arguments and override
enforcePermission->>evaluatePermission: risk level, mode, override, arguments
evaluatePermission->>resolveOverridePolicy: evaluate constraints
resolveOverridePolicy-->>evaluatePermission: selected policy or undefined
evaluatePermission-->>enforcePermission: permission result
enforcePermission-->>Caller: allow, deny, or approval requirement
🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches 💡 1🛠️ Fix failing CI checks 💡
🧪 Generate unit tests (beta)
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Greptile SummaryThis PR adds argument-aware permission overrides, including nested-path constraints, structural comparison, fallback policies, runtime fail-closed handling, public types, documentation, and an extensive constraint test suite.
Confidence Score: 1/5The PR is not safe to merge until stateful arguments cannot diverge after authorization and malformed array constraint containers cannot activate permission overrides. The permission guard can authorize one getter result and execute another from the same mutable argument object, while a nonempty array supplied as a malformed constraints container can still resolve an allow policy instead of failing closed. Files Needing Attention: packages/corsair/core/permissions/constraints.ts and packages/corsair/core/endpoints/bind.ts
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| Filename | Overview |
|---|---|
| packages/corsair/core/permissions/constraints.ts | Implements constraint resolution and defensive structural matching, but does not bind the evaluated accessor value to execution and accepts nonempty arrays as constraint maps. |
| packages/corsair/core/permissions/index.ts | Integrates constrained override resolution into the existing permission matrix and enforcement flow. |
| packages/corsair/core/endpoints/bind.ts | Forwards arguments into permission enforcement but later executes the original mutable argument object, enabling evaluated and executed values to diverge. |
| packages/corsair/core/plugins/index.ts | Widens the public permission configuration types to support constrained overrides while preserving flat policies. |
| packages/corsair/tests/permission-constraints.test.ts | Adds broad operator and fail-closed regression coverage but does not cover stateful getters or nonempty array constraint containers. |
| docs/concepts/permissions.mdx | Documents the new operators, fallback behavior, nested paths, and fail-closed semantics. |
Sequence Diagram
sequenceDiagram
participant Agent
participant Bound as Bound endpoint
participant Guard as Constraint evaluator
participant Provider
Agent->>Bound: Call with args
Bound->>Guard: Evaluate override against args
Guard-->>Bound: allow / fallback policy
alt allowed
Bound->>Provider: Execute endpoint with args
Provider-->>Agent: Result
else blocked
Bound-->>Agent: Denial or approval requirement
end
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Inline comments:
In `@docs/concepts/permissions.mdx`:
- Around line 300-306: Update the constraints explanation to state that a
matching constrained override can replace the mode-matrix policy, including
allowing an operation the matrix would require approval for. Restrict the
fail-closed fallback statement to missing, invalid-type, invalid-regex, empty,
or otherwise non-matching constraints, which contribute nothing and defer to
otherwise or the mode matrix.
In `@packages/corsair/core/permissions/constraints.ts`:
- Around line 23-25: Update the path resolution and constraint evaluation around
the visible path traversal and operator handling so only own argument properties
are traversed, unresolved paths yielding undefined are rejected, and each
constraint contains exactly one own recognized operator with a valid operand
type before evaluation; preserve fail-closed behavior for missing notIn paths
and malformed or multiple operators, and add regression tests covering missing
paths, inherited paths such as constructor.name, and malformed operators.
- Around line 56-57: Update the permission constraint matching around
RegExp.prototype.test to prevent agent-controlled patterns from causing
event-loop blocking: validate and reject unsafe backtracking expressions during
configuration loading, or replace the matcher with a linear-time regex engine.
Do not rely on a pattern-length limit alone, and preserve the existing
constraint match behavior for accepted patterns.
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docs/concepts/permissions.mdxpackages/corsair/core/client/index.tspackages/corsair/core/endpoints/bind.tspackages/corsair/core/index.tspackages/corsair/core/permissions/constraints.tspackages/corsair/core/permissions/index.tspackages/corsair/core/plugins/index.tspackages/corsair/tests/permission-constraints.test.ts
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Three ways a constraint could read as satisfied without actually gating the call, each of which applied the override's (typically looser) policy: - notIn on a missing argument. "undefined is not in the denylist" evaluated true, so an agent could bypass a notIn-guarded allow by omitting the field entirely. This contradicted the documented contract that an absent argument never satisfies a constraint. - A constraint carrying several operators enforced only the first one checked, leaving the developer believing both gated the call. - A non-array operand for in/notIn threw a TypeError out through enforcePermission into the endpoint call rather than failing closed, and a non-string match operand was silently coerced into a pattern. Resolve paths through own properties only: an inherited member such as toString is not an argument the agent passed, and resolving one would judge something other than the actual call. Also corrects the docs, which claimed constraints "never grant access the mode matrix wouldn't" — the opposite of the feature's purpose and of the #general example directly above it.
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Inline comments:
In `@packages/corsair/core/permissions/constraints.ts`:
- Around line 63-70: Update soleOperator to require exactly one own key on the
constraint and ensure that key is a supported operator, returning null for any
additional or unrecognized key; add a regression test covering one valid
operator plus an unknown key and verify it is rejected.
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soleOperator scanned for known operators and ignored everything else, so a
constraint with one valid operator plus an unrecognized key evaluated on the
valid one alone.
That is not inert. A misspelled operator is the likely real case:
{ match: '.*', notin: ['bad@evil.com'] }
'notin' was dropped, '.*' matched everything, and a policy:'allow' override
permitted exactly the address the developer meant to deny. A misspelled
operator on its own already failed closed; only the pairing slipped through.
Require exactly one own key and require it to be a supported operator, via
Reflect.ownKeys so an unrecognized key is seen rather than skipped. Symbol
keys are never operators.
sameValue compared non-primitives with JSON.stringify, which makes equality
depend on key insertion order. For notIn that inverts into a bypass: an
argument written {b, a} was not recognised in a denylist holding {a, b}, so a
policy:'allow' override permitted the payload it was configured to deny.
JSON.stringify also throws outright on a circular argument, sending a
TypeError out through enforcePermission into the endpoint call.
Replace it with a structural comparison that is key-order independent, stays
order-sensitive for arrays, compares dates by value (the one exotic type the
JSON form handled meaningfully), and terminates on cycles. Objects on the
current comparison path are tracked and released on the way out, so a value
legitimately repeated across two branches is still compared rather than
short-circuiting to equal.
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Inline comments:
In `@packages/corsair/core/permissions/constraints.ts`:
- Around line 65-68: Update the cycle-tracking logic around the relevant
constraint comparison function: store each active object pair as an a-to-b
mapping, and when a repeats, return true only if it is mapped to the same b;
otherwise continue or reject the comparison as appropriate. Preserve cleanup of
active mappings when unwinding recursion, and add a regression test covering the
non-isomorphic cyclic values described.
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The cycle guard tracked only the left-hand object, so any repeat of `a`
returned true without confirming `b` was the object `a` had been paired with.
A circular argument therefore compared equal to a structurally different
value — {self: <cycle>} matched {self: {}} — letting a non-matching call
satisfy an equals or in constraint and take a policy:'allow' override.
Track the a -> b pairing and require the same b when a recurs. Isomorphic
cyclic values still compare equal; non-isomorphic ones no longer do.
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Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>
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Greptile AI correctly identified that null overrides crash permission checks. If unchecked JavaScript configuration supplies null for an endpoint override, resolveOverridePolicy would dereference null.constraints, causing a TypeError instead of falling back to the permission matrix. The fix adds || override === null to the existing undefined guard so null is handled the same way as undefined — returning undefined to fall through to the mode matrix.
Verifies that resolveOverridePolicy returns undefined for null input instead of crashing with a TypeError. Uses resolveOverrideNullable wrapper that accepts PermissionOverride | null | undefined in its type signature to avoid any type assertion in test code, following CONTRIBUTING.md type safety guidelines.
Greptile AI identified that deepEqual's object branch compares by enumerable own keys (Object.keys). Exotic built-ins (RegExp, Map, Set, Promise, Error) and class instances have no enumerable own-key representation of their semantics, so two distinct instances compare as equal - bypassing the permission mode matrix. Adds isPlainObject() helper that checks Object.getPrototypeOf === Object.prototype for the object branch in deepEqual. Arrays and Date objects are already handled by their own paths before this check.
Verifies that exotic built-ins (RegExp, Map, Set) and class instances are never compared as equal in deepEqual. Includes three test cases: different RegExp instances, same-pattern RegExp instances, empty class instances, and Map-vs-plain-object cross comparison. These prevent a security bypass where a constraint using equals/in/notIn could be satisfied by a structurally different exotic argument.
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@greptileai review |
The previous cycle guard used Map tracking only the left-hand object (a). When a two-node cyclic graph {a1-a2} was compared against a one-node graph {b-b}, both a1 and a2 mapped to the same b, causing a recurring (a1, b) pair to return true - even though the topologies are different. Replaces with a Set of combined pair keys using WeakMap-assigned IDs. Each (a, b) pair gets a unique key, so (a1, b) and (a2, b) are tracked as separate entries. This ensures cyclic isomorphism checks are topology-aware.
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@greptileai review |
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All 9 fixes look correct. Working through each one against the implementation:
7–9. Cycle guard — The bidirectional partner tracking ( The runtime-validation approach in On the DAG limitation you flagged: keep the current behavior. The argument is correct: value equality (not reference equality) is the only sensible semantics for config operands that arrive through JSON. One thing worth confirming is intentional: This is ready to merge from a correctness standpoint. |
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All 9 P1 findings are verified fixed. Working through them against the current 1. 2. Key-order-dependent equality — 3. Malformed constraints silently dropping operators — 4. Non-record constraint containers throwing — 5. Null override crashing — 6. Exotic objects comparing as equal — 7. & 8. Cycle guard conflating nodes / single-direction pairing — 9. Asymmetric bidirectional pairing (55b5210) — Revisit now requires One implementation detail worth a note for future maintainers: The DAG aliasing caveat you flagged is the right call. Failing closed on any cycle would be overly conservative for JSON-parsed configs where reference sharing is unrepresentable, and strict aliasing semantics would break value equality for the most common case ( 69 tests, zero type assertions in |
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The implementation looks solid — all 9 P1 findings are confirmed fixed. Walking through the key ones:
Structural equality is key-order independent —
Bidirectional cycle guard — both
The acknowledged DAG limitation is the right call. Fail-closed-on-cyclic would be more conservative but would reject JSON-parsed configs that legitimately share references after a round-trip — not worth breaking the common case for a theoretical structural aliasing edge. One minor observation: 69 tests covering primitives, exotics, cycles through arrays and nested levels, hostile paths, and operator operand edges — this is thorough. The three design decisions in the PR description (fallback to mode matrix, empty-map-unsatisfied, and |
…ng them The bidirectional pairing guard still compared non-isomorphic cyclic graphs equal: a two-node ring matched a tail entering a two-node ring because the overwritten root pairing was never rechecked. This was the fourth successive counterexample to a pairing-based cycle guard. Cycles are now rejected outright: matchesConstraint returns false when either the value or the operand contains a reference cycle (path-based detection, so DAG-shared values are unaffected). JSON cannot express cycles, so config operands and MCP arguments are never cyclic in legitimate use; comparing cyclic graphs correctly requires graph isomorphism, not value equality, and a security boundary should refuse rather than approximate. This also closes the notIn inversion, where an uncomparable cyclic value would otherwise read as not-in the denylist. The cycle-guard machinery (pair keys, partner maps, visited set) is deleted; deepEqual is now a plain structural comparator. Tests updated to the new semantics plus new coverage for the notIn hole, cyclic operands, and cyclic list entries.
…overflow The recursive containsCycle scan threw RangeError (Maximum call stack size exceeded) on deeply nested acyclic arguments - depth ~10k in a measured reproduction - so the endpoint call rejected instead of falling back to otherwise or the mode matrix. The same unbounded recursion existed in deepEqual. Both are now iterative with explicit stacks: containsCycle uses a frame stack preserving the same path enter/leave discipline as recursive DFS, and deepEqual uses an explicit pair stack. Deep values now compare by value like any other structure, which also keeps notIn semantics honest - no overflow can silently produce a false that would read as not-in the denylist. Regression tests cover 20k-depth object and array structures under equals and notIn, with positive controls at normal depth.
Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>
…roperty Regression tests for the iterative containsCycle scan: an own enumerable property whose value is undefined is a real child, so frame exhaustion must be detected by length rather than by the popped value. Covers both key orders (the frame stack pops children in reverse insertion order) plus an equals case. Also documents in-code why the length check exists.
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Co-Authored-By: Claude <noreply@anthropic.com>
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@greptileai Fixed the shared-DAG exponential traversal finding in
Validation: 77/77 permission-constraint tests pass, Corsair TypeScript checking passes, Biome passes, and |
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When an agent-authored argument getter returns an allowlisted value during resolveArgPath and a disallowed value during endpoint execution, the constraint evaluator authorizes the first value while the provider receives the second, bypassing the required approval. How this was verified: Endpoint binding passes the same original argument object to permission enforcement and later to the provider endpoint.
Knowledge Base Used:
| if (!isRecord(constraints)) return false; | ||
| const entries = tryOwnEntries(constraints); |
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When unchecked configuration supplies a nonempty array such as [{ equals: "x" }] for constraints, Object.entries treats index 0 as an argument path, so an argument with a matching numeric property activates the configured allow policy instead of failing closed. How this was verified: The runtime config is cast without validation, arrays pass isRecord, and a satisfied numeric entry flows directly to the override policy.
| if (!isRecord(constraints)) return false; | |
| const entries = tryOwnEntries(constraints); | |
| if (!isRecord(constraints) || isUnknownArray(constraints)) return false; | |
| const entries = tryOwnEntries(constraints); |
Knowledge Base Used:
3 participants
Description
Closes #283. Design was proposed on the issue first (comment) — the three open questions from it are restated at the bottom, since they're shape decisions rather than implementation details and I'd rather they get reviewed explicitly than merged by default.
Endpoint overrides currently answer "may the agent call
messages.postat all?". Real authorization needs "may it call it with these arguments?" — posting to#generalwithout approval while an external DM still escalates.Config shape
overridesvalues widen fromPermissionPolicyto a union. Every existing config keeps compiling and behaves identically — constraints are opt-in:The motivating case from the issue:
Under
stricta write escalates torequire_approval. With that constraint,#generaland#alertsrun immediately; every other channel still escalates. Constraint keys are dot-notation paths into the endpoint's arguments, so'message.to': { match: '@corsair\\.dev$' }reaches nested payloads.Placement
Evaluation lives in
evaluatePermission, which runs before any database work inenforcePermission— so a constraint-allowed call creates no approval record at all, rather than creating one and immediately resolving it.Fails closed
A constraint is not satisfied when the argument is absent, is the wrong type for the operator (a number never matches a regex), the regex is malformed, or the constraints map is empty. When constraints don't hold the override contributes
otherwise, or nothing at all, leaving the mode matrix to decide — so a constraint can only narrow where a loosened policy applies, never widen it.Tests
packages/corsair/tests/permission-constraints.test.ts— 19 tests:matchand structural comparison for object operandsotherwisewhen specifiedstrict+ allowlisted channel →allow) and tightening (cautious+ denylisted recipient →deny)enforcePermission, asserting the allowed case returns{ result: 'allow' }with no approval recordChecklist
pnpm lintand all checks passpnpm typecheckand there are no TypeScript errorspnpm buildand all packages build successfullypnpm testand all tests passScreenshots / Demos (if applicable)
No UI or CLI surface — this is a core permission-evaluation change. The working proof is the test run on this PR:
https://github.com/corsairdev/corsair/pull/896/checks
(
postgres-js-database.test.tsneeds a live Postgres and is excluded locally; it is unaffected by this change.) Also clean locally:tsc --noEmit,tsc --build --force,biome checkacross 113 files, andvalidate:docs.Additional Notes
No breaking changes, no new dependencies, no schema or migration changes. Docs updated in
docs/concepts/permissions.mdxwith the operator table, the nested-path andotherwiseforms, and the fail-closed rules.Three decisions I'd like reviewed rather than assumed:
policy, so constraints can only narrow.otherwisecovers the tighten case.{}reading as "matches everything" would silently apply the loosened policy to every call, which seemed wrong for a security feature — but it is a judgement call.matchaccepts arbitrary regex from config. Patterns are developer-authored, but the values they test are agent-controlled, so a catastrophic-backtracking pattern could be made slow by a hostile argument. I documented it with a note to keep patterns anchored. If you'd rather not accept arbitrary regex at all,equals/in/notIncover the issue's examples and I'm happy to dropmatch.Summary by CodeRabbit
New Features
Documentation