Linux共享内存只允许读取访问

I have a parent process that allocates shared memory and writes to it. It also starts child processes that only read the shared memory. However I don't have any control over the insights of those child processes. They are written by other programmers. These child processes are not supposed to write on the shared memory. So I wondered if I can allow them read permissions, but not write access.I have a parent process that allocates shared m