> On Jul 11, 2018, at 12:22 AM, David Howells <dhowe...@redhat.com> wrote: > > Andy Lutomirski <l...@amacapital.net> wrote: > >>> sfd = fsopen("ext4", FSOPEN_CLOEXEC); >>> write(sfd, "s /dev/sdb1"); // note I'm ignoring write's length arg >> >> Imagine some malicious program passes sfd as stdout to a setuid >> program. That program gets persuaded to write "s /etc/shadow". What >> happens? You’re okay as long as *every single fs* gets it right, but that’s >> asking a lot. > > Do note that you must already have CAP_SYS_ADMIN to be able to call fsopen().
If you’re not allowing it already, someone will want user namespace root to be able to use this very, very soon.