Date: Fri, 30 Jun 2000 11:09:03 +0100 From: Brian Somers <brian@Awfulhak.org> To: Doug Barton <Doug@gorean.org> Cc: John Hay <jhay@mikom.csir.co.za>, Sheldon Hearn <sheldonh@uunet.co.za>, arch@FreeBSD.ORG, brian@hak.lan.Awfulhak.org Subject: Re: mergemaster: Change in description of envar handling Message-ID: <200006301009.LAA18177@hak.lan.Awfulhak.org> In-Reply-To: Message from Doug Barton <Doug@gorean.org> of "Thu, 29 Jun 2000 12:05:25 PDT." <Pine.BSF.4.21.0006291200110.7874-100000@dt052n3e.san.rr.com>
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> On Thu, 29 Jun 2000, John Hay wrote:
>
> > >
> > > No. I already conceded part of this point a while back when I developed
> > > the .mergemasterrc mechanism so that people could specify their own PATH
> > > (among other things), so there is already a way out of this for those
> > > who are not interested in specifying the full path to their PAGER. I'm
> > > definitely not going to support a text change which moves away from
> > > encouraging "best practice."
> >
> > Can you tell me why it is good practise to use full paths for environment
> > variables, because I don't understand it.
>
> Essentially, it's the same argument as not putting '.' in the
> PATH. Are there bigger, more important security holes to worry
> about? Absolutely. That doesn't mean that doing what you can to improve
> security isn't worthwhile.
Sorry to press the point, but it's not. Having a PAGER with an
unqualified program is exactly as secure as your PATH.
Looking at the mergemaster code, it looks wrong.
o It's ok if PAGER = more - what's so special about more ?
o It checks if -x ${PAGER%% *} - looking potentially for an
executable in the current directory.
I'm guilty of introducing that second bug...
Perhaps it should be this:
Index: mergemaster.sh
===================================================================
RCS file: /home/ncvs/src/usr.sbin/mergemaster/mergemaster.sh,v
retrieving revision 1.8
diff -u -r1.8 mergemaster.sh
--- mergemaster.sh 2000/05/12 03:09:57 1.8
+++ mergemaster.sh 2000/06/30 10:04:40
@@ -252,7 +252,7 @@
#
case "${DONT_CHECK_PAGER}" in
'')
- while [ "${PAGER}" != "more" -a -n "${PAGER}" -a ! -x "${PAGER%% *}" ]; do
+ while ! type "${PAGER%% *}" >/dev/null && [ -n "$PAGER" ]; do
echo " *** Your PAGER environment variable specifies '${PAGER}', but"
echo " I cannot execute it. In general it is good practice to"
echo " specify the full path for environment variables like"
Of course the more descriptive text stuff about PATH being altered
should still be added.
BTW, the [ -n "$PAGER" ] *should* be done first but isn't because
there seems to be a bug in sh where you can't say
while program1 && ! program2
but you can say
while ! program2 && program1
--
Brian <brian@Awfulhak.org> <brian@[uk.]FreeBSD.org>
<http://www.Awfulhak.org>; <brian@[uk.]OpenBSD.org>
Don't _EVER_ lose your sense of humour !
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