auth: initial implementation + some filesystem checks

kernel-src/sys/auth.c

@@ -0,0 +1,36 @@
+#include <kernel/auth.h>
+
+static authscope_t scopes[AUTH_SCOPE_COUNT];
+
+void auth_registerlistener(int _scope, authlistener_t listener) {
+	authscope_t *scope = &scopes[_scope];
+	for (int i = 0; i < AUTH_LISTENER_LIMIT; ++i) {
+		if (scope->listeners[i])
+			continue;
+
+		scope->listeners[i] = listener;
+		break;
+	}
+}
+
+int auth_check(int _scope, cred_t *cred, int actions, void *arg0, void *arg1, void *arg2) {
+	if (cred == NULL || actions == 0)
+		return 0;
+
+	authscope_t *scope = &scopes[_scope];
+
+	int allow = 0;
+	for (int i = 0; i < AUTH_LISTENER_LIMIT; ++i) {
+		authlistener_t listener = scope->listeners[i];
+		if (listener == NULL)
+			continue;
+
+		int decision = listener(cred, actions, arg0, arg1, arg2);
+		if (decision == AUTH_DECISION_DENY)
+			return EPERM;
+
+		allow += decision;
+	}
+
+	return allow ? 0 : EPERM;
+}