From owner-cvs-all  Thu Jan  4 10:14:57 2001
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To: Paul Richards <paul@freebsd-services.co.uk>
Cc: Dag-Erling Smorgrav <des@ofug.org>,
	Paul Richards <paul@FreeBSD.org>, cvs-committers@FreeBSD.org,
	cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/usr.sbin/pkg_install/update pkg_update.pl 
References: <3A54A329.3A84087F@freebsd-services.co.uk> 
In-Reply-To: <3A54A329.3A84087F@freebsd-services.co.uk> ; from Paul Richards <paul@freebsd-services.co.uk>  "Thu, 04 Jan 2001 16:22:01 GMT."
Date: Thu, 04 Jan 2001 20:14:02 +0200
From: Mark Murray <mark@grondar.za>
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> > > > >   "+REQUIRES" since ">+" is a valid open mode.
> > > > This would not be a problem if you used sysopen() instead of open().
> > > Even better - properly sanitise $file using taint-like checking.
> 
> Taint wouldn't actually solve this problem, since + is a valid part of
> the filename.

Aaaah! but you could deal with it by making sure there is a space in front
of it!

open FOO, "> $bar" or die "...";

is pretty darn safe, particularly if you have already sanitised $bar.

(say)
if (/^(+?[a-zA-Z0-9]+)$/) {
	open FOO, "< $1" or die "...";
	:
}

has very few (if any) nasty surprises waiting in the wings. Illegally
long file name is about the nastiest.

M
-- 
Mark Murray
Warning: this .sig is umop ap!sdn


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