Function sepgsql_fmgr_hook

contrib/sepgsql/label.c:310–395

* sepgsql_fmgr_hook * * It switches security label of the client on execution of trusted * procedures. */

 * procedures.
 */
static void
sepgsql_fmgr_hook(FmgrHookEventType event,
				  FmgrInfo *flinfo, Datum *private)
{
	struct
	{
		char	   *old_label;
		char	   *new_label;
		Datum		next_private;
	}		   *stack;

	switch (event)
	{
		case FHET_START:
			stack = (void *) DatumGetPointer(*private);
			if (!stack)
			{
				MemoryContext oldcxt;

				oldcxt = MemoryContextSwitchTo(flinfo->fn_mcxt);
				stack = palloc(sizeof(*stack));
				stack->old_label = NULL;
				stack->new_label = sepgsql_avc_trusted_proc(flinfo->fn_oid);
				stack->next_private = 0;

				MemoryContextSwitchTo(oldcxt);

				/*
				 * process:transition permission between old and new label,
				 * when user tries to switch security label of the client on
				 * execution of trusted procedure.
				 *
				 * Also, db_procedure:entrypoint permission should be checked
				 * whether this procedure can perform as an entrypoint of the
				 * trusted procedure, or not. Note that db_procedure:execute
				 * permission shall be checked individually.
				 */
				if (stack->new_label)
				{
					ObjectAddress object;

					object.classId = ProcedureRelationId;
					object.objectId = flinfo->fn_oid;
					object.objectSubId = 0;
					sepgsql_avc_check_perms(&object,
											SEPG_CLASS_DB_PROCEDURE,
											SEPG_DB_PROCEDURE__ENTRYPOINT,
											getObjectDescription(&object, false),
											true);

					sepgsql_avc_check_perms_label(stack->new_label,
												  SEPG_CLASS_PROCESS,
												  SEPG_PROCESS__TRANSITION,
												  NULL, true);
				}
				*private = PointerGetDatum(stack);
			}
			Assert(!stack->old_label);