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fix(api-server): handle Keycloak service-account- prefix in OIDC username matching #1465

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mergify merged 1 commit into from
Apr 24, 2026
Merged

fix(api-server): handle Keycloak service-account- prefix in OIDC username matching #1465

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14 changes: 12 additions & 2 deletions components/ambient-api-server/pkg/middleware/bearer_token_grpc.go
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@ func bearerTokenGRPCUnaryInterceptor(expectedToken, serviceAccountUsername strin
return handler(withCallerType(ctx, CallerTypeService), req)
}
if username := usernameFromJWT(token); username != "" {
if serviceAccountUsername != "" && username == serviceAccountUsername {
if isServiceAccount(username, serviceAccountUsername) {
ctx = withCallerType(ctx, CallerTypeService)
}
return handler(auth.SetUsernameContext(ctx, username), req)
Expand All @@ -56,7 +56,7 @@ func bearerTokenGRPCStreamInterceptor(expectedToken, serviceAccountUsername stri
}
if username := usernameFromJWT(token); username != "" {
ctx := auth.SetUsernameContext(ss.Context(), username)
if serviceAccountUsername != "" && username == serviceAccountUsername {
if isServiceAccount(username, serviceAccountUsername) {
ctx = withCallerType(ctx, CallerTypeService)
}
return handler(srv, &serviceCallerStream{ServerStream: ss, ctx: ctx})
Expand Down Expand Up @@ -93,6 +93,16 @@ func usernameFromJWT(tokenString string) string {
return ""
}

const keycloakServiceAccountPrefix = "service-account-"

func isServiceAccount(jwtUsername, configuredAccount string) bool {
if configuredAccount == "" {
return false
}
return jwtUsername == configuredAccount ||
jwtUsername == keycloakServiceAccountPrefix+configuredAccount
}
Comment on lines +98 to +104
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@coderabbitai coderabbitai Bot Apr 24, 2026

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⚠️ Potential issue | 🟠 Major

Service caller attribution is tied only to username text, which is too weak for authz.

At Line 102-Line 103, isServiceAccount grants service caller status from preferred_username pattern alone. Since CallerTypeService gates privileged paths (e.g., inbox stream access), this should also bind to a client identity claim (e.g., azp/client_id) rather than username shape only.

Proposed hardening 
-func isServiceAccount(jwtUsername, configuredAccount string) bool {
+func isServiceAccount(jwtUsername, jwtAZP, configuredAccount string) bool {
 	if configuredAccount == "" {
 		return false
 	}
+	if jwtAZP != configuredAccount {
+		return false
+	}
 	return jwtUsername == configuredAccount ||
 		jwtUsername == keycloakServiceAccountPrefix+configuredAccount
}

Then pass azp extracted from JWT at the two call sites (Line 32 and Line 59).

🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@components/ambient-api-server/pkg/middleware/bearer_token_grpc.go` around
lines 98 - 104, isServiceAccount currently treats a JWT as a service account
solely by preferred_username pattern; change its signature to accept and
validate the client identity (azp/client_id) as well and require that azp
matches the configuredAccount (or a configured service client id) in addition to
the username check. Update the two call sites that invoke isServiceAccount (the
handlers that extract preferred_username) to also extract the azp/client_id
claim from the parsed JWT and pass it into the revised isServiceAccount
signature (adjust any variable names such as jwtUsername and configuredAccount
to include jwtAzp/jwtClientID), and ensure the logic enforces both username
pattern OR explicit client id match before returning true.


type serviceCallerStream struct {
grpc.ServerStream
ctx context.Context
Expand Down
23 changes: 23 additions & 0 deletions components/ambient-api-server/pkg/middleware/bearer_token_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,29 @@ func TestExtractBearerToken(t *testing.T) {
}
}

func TestIsServiceAccount(t *testing.T) {
tests := []struct {
name string
jwtUsername string
configuredAccount string
want bool
}{
{"exact match", "ocm-ams-service", "ocm-ams-service", true},
{"keycloak prefixed match", "service-account-ocm-ams-service", "ocm-ams-service", true},
{"no match", "other-user", "ocm-ams-service", false},
{"empty configured", "service-account-ocm-ams-service", "", false},
{"empty jwt username", "", "ocm-ams-service", false},
{"partial prefix no match", "service-account-other", "ocm-ams-service", false},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if got := isServiceAccount(tt.jwtUsername, tt.configuredAccount); got != tt.want {
t.Errorf("isServiceAccount(%q, %q) = %v, want %v", tt.jwtUsername, tt.configuredAccount, got, tt.want)
}
})
}
}

func TestBearerTokenAuth(t *testing.T) {
const validToken = "test-secret-token"
handler := BearerTokenAuth(validToken)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
Expand Down
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