Benjamin Smith wrote:
On Tuesday 26 February 2008, Ralph Angenendt wrote:
There is no mechanism for escaping untrusted input?
Correct. At least there's no magic quoting function.
Ok. So I'm going to have to pull up my sleeves and do this with sed/awk pipes.
Got it. I'll quit looking for a simply solution to this (I thought) simple
problem.
Now for a more philosophical question....
WHY THE @!#! NOT?!?!?
The shell is 'supposed' to be run by a user that is allowed to run any
command he wants, and permission/trust issues are handled by the
login/authentication process that happens before you get to the shell.
If you give the shell a bad command under your own account, it's not
supposed to second guess what you wanted.
Bash is used, extensively in many cases, to deal with untrusted data.
Why?
This can
include random file names in user home directories, parameters on various
scripts, etc. It's highly sensitive to being passed characters that have,
over the past NN years, resulted in quite a number of security holes and
problems.
If it hurts, don't do it. Build your own argument list and exec
programs directly if you want to avoid shell command line parsing.
Yet there exists NO MECHANISM for simply ensuring that a given argument is an
escaped string?
What does that mean? If you can define it you can make it happen, but
who knows what characters at what depth of quoting will have some
special meaning?
How many "homebrew" ISP or hosting administration scripts could be compromised
by simply putting a file in your home directory called ";rm -rf /" ?
Probably none that are still in business.
This doesn't strike you as fundamentally borkeD?
No, if you stop bad things from happening, you'll also stop good things.
Why would we accept a work
environment that is effectively laden with randomly placed, loaded rat traps?
Not trying to bash (ahem) bash needlessly, but this is a problem that so
smacks of 1977...
The problem is that you aren't using the shell as intended. If you run
it under your own user id, it does exactly what you tell it to do and
there is no element of trust involved.
I guess I just hadn't noticed how bad this was, since I started using PHP as
shell scripts years ago to run everything, despite the mild performance hit.
escapeshallarg() and addslashes() combined with a few backticks provides easy
access to the power of the shell, and excellent "don't need to worry about
it" security.
Errr what??? Php has about the worst security history of any program
around.
This just blows my mind....
What would you like your computer to prevent you from doing to yourself?
--
Les Mikesell
lesmikesell@xxxxxxxxx
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