Dear Casper and Dan,
If you can control<pid>, then clearly you have access the file anyway
simply by controlling it using a debugger.
Sorry, but no. The "attacker" has the file opened O_RDONLY, and cannot
"upgrade" that to O_RDWR.
Paul Szabo psz () maths usyd edu au http://www.maths.usyd.edu.au/u/psz/
School of Mathematics and Statistics University of Sydney