Permission Resolution

This document explains how Pragmatic.Authorization resolves permissions at runtime: the provider chain, caching layers, and wildcard matching internals.

Overview

Permission resolution is a three-phase process:

1. Provider chain — Multiple IPermissionProvider implementations run in order, each contributing permissions.
2. Caching — Results are cached per request (always) and optionally cross-request via ICacheStack (using CacheCategories.Permissions).
3. Matching — WildcardMatcher checks if any resolved permission matches the required one.

The Provider Chain

IPermissionProvider is the extension point. Each provider has an Order value that determines execution sequence. Results from all providers are merged with union semantics (additive only, no provider can remove permissions added by another).

public interface IPermissionProvider
{
    int Order { get; }
    ValueTask<IReadOnlySet<string>> ResolvePermissionsAsync(
        ICurrentUser user, CancellationToken ct = default);
}

Built-in Providers

Provider	Order	Source	Registered when
ClaimsPermissionProvider	0	ICurrentUser.Claims["permission"]	Always
RoleExpansionProvider	100	IRolePermissionStore	Roles are mapped or custom store registered
GroupExpansionProvider	200	IGroupRoleStore + IRolePermissionStore	Groups are mapped or custom store registered

ClaimsPermissionProvider

The base provider. Reads the "permission" claim from ICurrentUser.Claims and returns each value as a permission string.

User claims: { "permission": ["booking.reservation.read", "catalog.amenity.read"] }
Result: HashSet { "booking.reservation.read", "catalog.amenity.read" }

RoleExpansionProvider

For each "role" claim on the user, queries IRolePermissionStore.GetPermissionsForRoleAsync(roleName) and merges results.

User claims: { "role": ["booking-manager"] }

IRolePermissionStore lookup:
  "booking-manager" -> { "booking.reservation.*", "booking.guest.*", "catalog.property.read" }

Result: HashSet { "booking.reservation.*", "booking.guest.*", "catalog.property.read" }

GroupExpansionProvider

For each "group" claim on the user, queries IGroupRoleStore.GetRolesForGroupAsync(groupName) to get roles, then queries IRolePermissionStore.GetPermissionsForRoleAsync(roleName) for each role.

User claims: { "group": ["customer-care"] }

IGroupRoleStore lookup:
  "customer-care" -> { "booking-manager", "catalog-viewer" }

IRolePermissionStore lookup:
  "booking-manager" -> { "booking.reservation.*", "booking.guest.*", "catalog.property.read" }
  "catalog-viewer" -> { "catalog.amenity.read", "catalog.property.read" }

Result: HashSet { "booking.reservation.*", "booking.guest.*", "catalog.property.read", "catalog.amenity.read" }

Custom Providers

Register via AuthorizationBuilder:

authz.AddPermissionProvider<ExternalPermissionProvider>();

Or via CompositePermissionProvider, which aggregates multiple IPermissionProvider instances excluding itself (to avoid recursion). CompositePermissionProvider has Order -1, running before all others.

Resolution Flow

Request arrives
  |
  v
CachedPermissionResolver.ResolvePermissions()
  |
  +-- Cached? --> Return cached set
  |
  +-- ICacheStack enabled? --> Check ICacheStack (Permissions category)
  |   |
  |   +-- Cache hit? --> Return cached set
  |   |
  |   +-- Cache miss? --> Run provider chain, cache result
  |
  +-- No cross-request cache --> Run provider chain
  |
  v
For each IPermissionProvider (ordered by Order):
  Call ResolvePermissionsAsync(user)
  Merge into HashSet<string> (union)
  |
  v
Store result as _resolvedPermissions (request-scoped)
  |
  v
Return IReadOnlySet<string>

CachedPermissionResolver

CachedPermissionResolver implements IUserAuthorization and is the runtime bridge between the provider chain and permission checks. It is registered as Scoped (one per request).

Request-Scoped Caching

Permissions are resolved lazily on first access to Permissions, HasPermission, HasAnyPermission, or HasAllPermissions. The resolved set is stored in _resolvedPermissions and reused for all subsequent checks within the same request.

Cross-Request Caching

When UsePermissionCache is configured and ICacheStack is available in DI, the resolved permissions are cached cross-request via the CacheCategories.Permissions category.

Cache key format:

• Single-tenant: {prefix}:{userId}
• Multi-tenant: {prefix}:{tenantId}:{userId}

Cache tags: ["user:{userId}"] (for targeted invalidation).

// Example: invalidate a specific user's cached permissions
await cacheStack.InvalidateByTagAsync($"user:{userId}");

Permission Matching

HasPermission(string required) checks in two steps:

1. Fast path: Exact match — resolved.Contains(required). This covers the most common case.
2. Slow path: Wildcard match — for each resolved permission that contains *, checks WildcardMatcher.Matches(granted, required).

// Example: user has ["booking.*"]
// HasPermission("booking.reservation.read")
//   Step 1: "booking.reservation.read" not in set (set contains "booking.*") -> false
//   Step 2: "booking.*" contains '*' -> WildcardMatcher.Matches("booking.*", "booking.reservation.read") -> true

Claims-Based Properties

CachedPermissionResolver also exposes claims-based properties:

Property	Claim type	Fallback
Roles	role	Empty array
Groups	group	Empty array
Scopes	scope	Empty array

These are read directly from ICurrentUser.Claims without provider chain resolution.

WildcardMatcher

WildcardMatcher is an internal static class that handles wildcard pattern matching for permissions. All matching is case-insensitive.

Matching Algorithm

Matches(string pattern, string permission) has three paths:

1. Exact match: string.Equals(pattern, permission, OrdinalIgnoreCase)
2. Global wildcard: pattern == "*" matches everything
3. Suffix wildcard: Pattern like "booking.*" (ends with .*, no *. inside) — checks if permission starts with the prefix ("booking.")
4. Segment wildcard: Pattern like "booking.*.read" or "*.reservation.read" — splits both strings on . and compares segment by segment, with * matching exactly one segment

Segment Matching Rules

When patterns and permissions have the same number of segments, each * matches any single segment:

Pattern:    booking.*.read
Permission: booking.reservation.read
Segments:   [booking, *, read] vs [booking, reservation, read]
Match:      booking=booking, *=reservation, read=read -> TRUE

When the pattern has a trailing * and fewer segments, it matches all remaining:

Pattern:    booking.*
Permission: booking.reservation.read
Trailing * detected -> check prefix: booking=booking -> TRUE

When segment counts differ and there is no trailing *, it does not match:

Pattern:    booking.*.read
Permission: booking.reservation
Segments:   3 vs 2, no trailing * -> FALSE

ExpandWildcards

ExpandWildcards(patterns, allKnownPermissions) expands wildcard patterns against a known permission set. This is used for admin tooling (catalog) and WithoutPermissions validation.

var patterns = new[] { "booking.*", "catalog.amenity.read" };
var allKnown = new HashSet<string>
{
    "booking.reservation.read",
    "booking.reservation.create",
    "booking.guest.read",
    "catalog.amenity.read",
    "catalog.property.read"
};

var expanded = WildcardMatcher.ExpandWildcards(patterns, allKnown);
// Result: { "booking.reservation.read", "booking.reservation.create",
//           "booking.guest.read", "catalog.amenity.read" }

Observability

CachedPermissionResolver emits metrics via AuthorizationDiagnostics:

Event	Counter
Permission check called	permission_checks +1
Permission check denied	permission_denied +1
Resolved set reused within request	cache_hits +1
Resolved set computed (provider chain ran)	cache_misses +1

Performance Characteristics

Operation	Complexity
First permission check (cold)	O(P * R) where P = providers, R = roles/groups per user
Subsequent checks (warm)	O(1) exact match, O(N) wildcard scan where N = resolved permissions
Cross-request cache hit	O(1) ICacheStack lookup
Wildcard suffix match	O(1) string prefix check
Wildcard segment match	O(S) where S = number of segments

In practice, the resolved permission set is small (tens to low hundreds), making the wildcard scan negligible.

Configuration Reference

AuthorizationOptions

Property	Type	Default	Description
EnablePermissionCaching	bool	true	Enable request-scoped caching
PermissionClaimType	string	"permission"	Claim type for direct permissions
CacheOptions	PermissionCacheOptions?	null	Cross-request cache settings (null = disabled)
DefaultEndpointPolicy	DefaultEndpointPolicy	AllowAnonymous	Default endpoint authorization mode

PermissionCacheOptions

Property	Type	Default	Description
Expiration	TimeSpan	5 minutes	Cache entry TTL
KeyPrefix	string	"permissions"	Prefix for cache keys