Symbolic Links VS. Security

John Bruner jdb at mordor.UUCP
Thu Nov 22 06:35:47 AEST 1984


Symbolic links DO create additional security problems.  The presence
of symbolic links in 4.2BSD widens a security hole that existed in
4.1BSD (and I believe also exists in System V) into a yawning chasm.
I don't want to elaborate on this, other than to say that sometimes
it was indeed a feature that you could not hard link across filesystems.

I'm not opposed to symbolic links, but I do believe that more thought
should have been given to their implementation.  As just one example, 
the implementation of "chown" and "chmod" with respect to links is
inconsistent.  "chown" changes the owner of a link, but "chmod"
changes the mode of the file that the link points to.
-- 
  John Bruner (S-1 Project, Lawrence Livermore National Laboratory)
  MILNET: jdb at mordor.ARPA [jdb at s1-c]	(415) 422-0758
  UUCP: ...!ucbvax!dual!mordor!jdb 	...!decvax!decwrl!mordor!jdb



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