Re: [PATCH][RFC] 2.5.44 (1/2): Filesystem capabilities kernel patch

[Olaf Dietsche <olaf.dietsche#list.linux-kernel@t-online.de>]

Olaf Dietsche <olaf.dietsche#list.linux-kernel@t-online.de> writes:

> <chris@scary.beasts.org> writes:
>
>> On Mon, 28 Oct 2002, Olaf Dietsche wrote:
>>
>>> If you're careful with giving away capabilities however, this patch
>>> can make your system more secure as it is. But this isn't fully
>>> explored, so you might achieve the opposite and open new security
>>> holes.

Famous last words :-(

>>
>> Have you checked how glibc handles an executable with filesystem
>> capabilities? e.g. can an LD_PRELOAD hack subvert the privileged
>> executable?
>
> No, I didn't check. Thanks for this hint, I will look into this.

I just downloaded glibc 2.3.1 and would say you can subvert a
privileged executable with LD_PRELOAD. There's no mention of
PR_GET_DUMPABLE anywhere and __libc_enable_secure is set according to
some euid/egid tests.

Hopefully, someone more fluent in glibc issues can shed some light?
Is there a way to switch LD_PRELOAD off completely or on a needed
basis?

Regards, Olaf.