Re: Doubt: core not dumped when binary give up root privileges.

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

On Gwe, 2003-08-22 at 20:25, Alexandre Pereira Nunes wrote:
> The program explicitly sets RLIMIT_CORE to RLIM_INFINITY when still 
> running with uid 0.

The kernel assumes a core image from something that was priviledged may
be unsafe.

> If instead of calling the program as root, I call it from the non-priv 
> uid in question, if it crashes, it dumps core on the mentioned dir. 
> That's the desired behaviour, since I can then take the core and debug. 
> But if I run it as root (in fact, I would have to), and it crashes (or 
> is forced to ,by means of kill -SEGV), after it gives up root 
> credentials, it won't leave a core dump file, which in turn means I 
> cannot debug it later.
> 
> Any ideas?

2.4-ac has support for enabling setuid core dumps and setting the dump
path, so you can write such dumps to /root/dumps and the kernel will
make them root accessible only.

The 2.6 test tree and Marcelo 2.4 don't currently support this