Re: ver. 2.11.56 problems

[Chris Snyder]

Tom Cloyd wrote:
> Major lesson: the Unix/Linix command processor (or whatever - genie?) is
> disinterested in the fact that I'm already in the dir containing the
> referenced file. I have to tell it explicitly. Coming from Windows, I
> find this extremely confusing, nonsensical, etc., but I now suddenly
> understand why there are 75,000+ symlinks in my OS (unless, of course,
> I'm completely misunderstanding what symlinks are about).

I made the switch from DOS/Windows about six years ago, and remember the 
same confusion. There is a very good reason for this behavior: it 
provides a safeguard against malicious programs being accidentally 
executed. Consider the following example:

A user places an executable named "ls" in their home directory. This 
executable silently gives that user root-level access to the system, 
then calls the actual ls program. This program won't do anything if run 
by a normal user, of course. However, the malicious user asks the system 
administrator to take a look at their home directory to diagnose a 
problem they're having. The administrator changes to the user's home 
directory and runs ls to get a directory listing; unbeknownst to the 
administrator, the malicious ls has just given the user admin privileges 
using the privileges of the administrator that called it.

This isn't as big of a deal with single-user systems, but it still is a 
good way to make sure that users are aware that they're not executing 
system-supplied software.

Well, that explanation was longer than I thought it would be. Hopefully 
it's useful, or at least interesting.

-Chris