Re: pgsql/src/bin/initdb initdb.sh

Bruce Momjian writes:

> This brings up a question.  If I have pid 333 and someone creates a file
> world-writable called /tmp/333, and I go and do:
>
>     cat file >/tmp/$$
>
> isn't another user now able to modify those temp file contents.  Is that
> the insecurity you mentioned Peter, and if so, how do you prevent this?

That is one possibility.  Another exploit is with a symlink from /tmp/333
to a file you want to overwrite.  This is more fun with root, but it's
still not a good idea here.

To securely create a temp file in shell you need to use mktemp(1), or do
something like (umask 077 && mkdir $TMPDIR/$$) to create a subdirectory.
Needless to say, it's tricky.

--
Peter Eisentraut   peter_e@gmx.net   http://funkturm.homeip.net/~peter