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Date:      11 Oct 2002 09:39:07 -0700
From:      Ricardo Anguiano <anguiano@codesourcery.com>
To:        Chris BeHanna <behanna@zbzoom.net>
Cc:        FreeBSD Security <security@FreeBSD.ORG>
Subject:   Re: access() is a security hole?
Message-ID:  <m3r8exszf8.fsf@mordack.codesourcery.com>
In-Reply-To: <20021011094935.I86274-100000@topperwein.pennasoft.com>
References:  <20021011094935.I86274-100000@topperwein.pennasoft.com>

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Chris BeHanna <behanna@zbzoom.net> writes:

> On Fri, 11 Oct 2002, Bruce Evans wrote:
> > Setuid programs should only use access() to check whether they will
> > have permission after they set[ug]id() to the real [ug]id.  Non-setuid
> > programs mostly don't need such checks.  They can just try the operation.
> 
>     Perhaps the way to avoid the race is to open the file, lock it,
> and *then* call access(), then close the file or proceed based upon
> the result.

What's wrong with opening the file, then using fstat to check the
properties of the file associated with the file descriptor?

-- 
Ricardo Anguiano
CodeSourcery, LLC

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