Re: [PATCH v4 2/5] pid: Add PIDFD_IOCTL_GETFD to fetch file descriptors from processes

On Thu, Dec 19, 2019 at 5:43 PM Andy Lutomirski [off-list ref] wrote:

I don't think this is MODE_READ.  By copying an fd from the task, you
can easily change its state.

Would PTRACE_MODE_ATTACH_REALCREDS  work? I'm curious what
kind of state change you can cause by borrowing an FD?

IMO it would be really nice if pidfd could act more like a capability
here and carry a ptrace mode, for example.  But I guess it doesn't
right now.


--Andy