Re: Ptrace hole / Linux 2.2.25

Ben Pfaff
2003-03-17T18:28:41Z

Alan Cox <alan@redhat.com> writes:

> A patch for Linux 2.4.20/Linux 2.4.21pre is attached. The patch also
> subtly changes the PR_SET_DUMPABLE prctl. We believe this is neccessary and
> that it will not affect any software. The functionality change is specific
> to unusual debugging situations.

I am concerned about this change because it will break sandboxing
software that I have written, which uses prctl() to turn
dumpability back on so that it can open a file, setuid(), and
then execve() through the open file via /proc/self/fd/#. Without
calling prctl(), the ownership of /proc/self/fd/* becomes root,
so the process cannot exec it after it drops privileges. It uses
prctl() in other places to get the same effect in /proc, but
that's one of the most critical.
--
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