[PATCH] capabilities: Introduce CAP_RESTORE

[Nicolas Viennot]

> > If I understand part of CRIU correctly, then we only need read-access 
> > for the current user. I am sure Andrei, Pavel or Cyrill will correct 
> > me if I am wrong concerning map_files.
> If I do "ls -l /proc/self/map_files" I get the link name and link content.
> While I can't open /proc/self/map_files/7fbde0c3200-7fbde0c3300 I can read that it points to /usr/lib64/ld-2.30.so, which is something I can open and read. Sure, it's an extra step, but it's no big deal. It does raise the question of what value comes from disallowing open via the symlink.

Reading the symlink doesn't work in two cases:
1) The file has been deleted
2) The file is a memfd file