On Wed, 2005-06-08 at 21:39 +0300, Shachar Shemesh wrote: > Alon Altman wrote: > > > On Wed, 8 Jun 2005, Shachar Shemesh wrote: > > > >> Hi all, > >> > >> Does anyone know WHY only root can create hard links to directories? > >> What is the attack/problem this permission restriction is trying to > >> solve? > > > > > > Because only root can unlink a non-empty directory? > > I was hoping to learn something new from the answers, but I have to > admit that I didn't expect anything like that. > > WHY can root unlink a non-empty directory? Why is that useful? What's > the difference between that and "rm -r", and when would I want to use that? > > Congrats, Alon. Not only did you not answer my question, you've added to > the mystery :-)
My assumption: if you hard-link to a file not owned by you, inside a directory you do have write access to (otherwise you can't create the link), the file will of course be identical to the original file (it _is_ a hard-link). Meaning it will have the same owner, same permissions, and same bits in general. So... 1) I am in /home/shimi/test and my uid is 500 2) I do ln -d /sbin/ifconfig 3) If I do ls -li, I see "ifconfig" with the same inode of /sbin/ifconfig, owned by uid 0. 4) I try rm -rf ~/test - and I fail. I cannot erase the file "ifconfig" because it is not owned by me (even though I created it. bad!). I also can't erase the directory because it's non-empty (and I'm not root). Why can root erase a non-empty directory? If you want to dereference the directory but not the files. Why would you want to do that? I guess it could be related to hard-linked directories... ;) -- shimi <[EMAIL PROTECTED]> ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
