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