Date: Mon, 22 Apr 2002 16:07:42 -0400 From: Mike Barcroft <mike@FreeBSD.ORG> To: Garrett Wollman <wollman@lcs.mit.edu> Cc: "M. Warner Losh" <imp@village.org>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern kern_descrip.c kern_exec.c src/sys/sys filedesc.h Message-ID: <20020422160742.B8421@espresso.q9media.com> In-Reply-To: <200204190420.g3J4KMC69617@khavrinen.lcs.mit.edu>; from wollman@lcs.mit.edu on Fri, Apr 19, 2002 at 12:20:22AM -0400 References: <200204190045.g3J0jUY59526@freefall.freebsd.org> <200204190309.g3J39tE69057@khavrinen.lcs.mit.edu> <20020418.220125.06947209.imp@village.org> <200204190420.g3J4KMC69617@khavrinen.lcs.mit.edu>
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[Sorry for the late reply.]
Garrett Wollman <wollman@lcs.mit.edu> writes:
> <<On Thu, 18 Apr 2002 22:01:25 -0600 (MDT), "M. Warner Losh" <imp@village.org> said:
>
> > There is no other way to fix this than in the kernel...
>
> Sure there is -- make sure that every privileged process has something
> on every fd. You could do it in csu (although from a standards
> perspective that would make no difference). Or, alternatively, rather
> than changing exec(), you could change fdalloc() to never return fd 0,
> 1, or 2 except when explicitly requested by dup2() -- although this
> would break some seriously old programs that expect to be able to do
>
> fd = open(...)
> close(1);
> dup(fd);
>
> and have it work. (These programs are broken anyway -- the Standard
> does not guarantee any particular order of fd allocation.)
I agree that the current solution to this problem is wrong. I think
the most correct solution would be to fix each set[ug]id program to
ensure that it has a working set of the basic std{in,out,err}
descriptors by making a series of fstat() calls and watching for a
EBADF.
Best regards,
Mike Barcroft
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