Re: /tmp topic

[Tollef Fog Heen <tollef () ADD NO>]

* Max Gribov

| Mount /tmp with noexec option in /etc/fstab is a pretty secure
| thingto do...

At least under Linux, noexec is not very useful:  (I know this has
been disclosed on bugtraq before, but, obviously, not everybody knows
about it)

$cat hello.c
#include <stdio.h>

int main() {
  printf("hello world\n");
  return 0;
}
$gcc -o hello hello.c
$./hello
bash: ./hello: Permission denied
$/lib/ld-linux.so.2 ./hello
hello world

Basically - it all boils down to:

don't use /tmp, use $TMPDIR or $TMP, failing that use $HOME/tmp.  If
that fails, use /tmp with mkstemp/mkdtemp (like Kris Kennaway wrote)
or open(2) with O_EXCL.  If everything fails, bail out or give the
user warning and option to retry. (Whatever's appropriate for the
program)

--

Tollef Fog Heen
Unix _IS_ user friendly... It's just selective about who its friends are.