open_by_handle_at(2)的用途是什么？

Question

我从CAP_DAC_READ_SEARCH的docker breakout技术那里学到了这个系统调用。

我想知道这个系统调用最初是为了什么而设计的？或者它还有其他典型和常见的用法吗？因为经过一段时间的搜索，我发现open_by_handle_at(2)最重要的用法是从容器中突围出来……

Answer 1

来自man open_by_handle

   These system calls are designed for use by user-space file
   servers.  For example, a user-space NFS server might generate a
   file handle and pass it to an NFS client.  Later, when the client
   wants to open the file, it could pass the handle back to the
   server.  This sort of functionality allows a user-space file
   server to operate in a stateless fashion with respect to the
   files it serves.