• Korthrun
    3•15 days ago

    My dumbass can only come up with three:

    1. You are already root (ok, fine)
    2. You have made /dev/ writable by non-privileged users
    3. Your non-privileged user already owns the symlink /dev/nul. Which “ok, fine”, but also the point of command would have to be to functionally do nothing other than print out the error ln: failed to create symbolic link '/dev/nul': File exists

    I would love to understand the use case behind #2. I am also curious to see even 7 more cases, let alone your figurative million.

    In regards to #3 even if the behaviour of ln was to replace a symlink if it already existed, it’ll probably have to unlink() the existing symlink, which I’m pretty sure is gonna get you a permission denied error on any /dev filesystem with sane permissions.

    • Korthrun
      1•15 days ago

      Follow up, tested and confirmed #3:

      [korthrun@host]$ ls -l /dev/korth
.rw-r--r-- korthrun wheel 0 B Wed Jun 11 17:11:03 2025 /dev/korth
[korthrun@host]$ rm /dev/korth
rm: cannot remove '/dev/korth': Permission denied
    • @[email protected]
      1•15 days ago

      ln could be +s

      the kernel could have been modified

      I’m sure there is some way if using capabilities

      you don’t need to be ‘root’, uid 0 is enough :)