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Re: Ksh Shell script security question.( SOLVED)



On 2/15/07, Dan Nelson <dnelson_(_at_)_allantgroup_(_dot_)_com> wrote:

In the last episode (Feb 15), Thomas Dickey said:
> On Wed, Feb 14, 2007 at 10:57:12PM -0600, Dan Nelson wrote:
> > In the last episode (Feb 14), Dak Ghatikachalam said:
> > > I am am puzzled how to secure this code when this shell script is
> > > being executed.
> > >
> > > ${ORACLE_HOME}/bin/sqlplus -s  <<EOF | tee -a  ${RESTOREFILE}
[...]
> > > EOF
> > >
> > > When I run this code from shell script in /tmp directory it spews
> > > file called /tmp/sh03400.000 in that I have this entire code
> > > visible.
> >
> > I bet if you check the permissions you'll find the file has mode
> > 0600, which means only the user running the script can read the
> > file (at least that's what a test using the pdksh port does on my
> > system).  ksh93 does have a problem, though: it opens a file and
> > immediately unlinks it, but the file is world-readable for a short
> > time.
>
> Doesn't it (ksh93, etc) pay attention to umask?
> If it does, the script should use that feature.

It does honor umask, but I think temp files should be created mode 0600
in all cases.  A person may have a umask of 022 to allow normal files
to be read by group members but still not want them to see
here-document contents.  They may not even realize that their shell is
using tempfiles.  Some shells use pipes (bash and ash do; zsh uses an
0600 tempfile that it immediately unlinks; Solaris sh uses an 0600
tempfile).

> > Both ksh variants honor the TMPDIR variable, though, so if you create
a
> > ~/tmp directory, chmod it so only you can access it, then set
> > TMPDIR=~/tmp , you will be secure even if you're using ksh93.
>
> relatively (it's not a given that people haven't opened up ~/tmp)

I think if someone has gone to the trouble of creating a private ~/tmp
directory, they probably know what they're doing and know the
consequences of opening it up.



I appreciate all your response.

Thanks a lot for  insight  on unix fundementals

The issue I had is solved by doing  umask 077  at the start  of the script,
so what it did was it created the temporary files with  read+write  for
owner of the file , and in my process I also create directories while RMAN
backup is being run, so that umask 077 for directory gave  rwx for
directories while creation

This problem I had is solved now, it is secure

Thanks
Dak

--
        Dan Nelson
        dnelson_(_at_)_allantgroup_(_dot_)_com
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