oss-sec mailing list archives
Re: Fixing the glibc runtime linker
From: Tim Brown <tmb () 65535 com>
Date: Fri, 20 Feb 2015 06:30:41 +0000
On Friday 20 February 2015 01:38:31 Paul Pluzhnikov wrote:
On Thu, Feb 19, 2015 at 2:19 PM, Tim Brown <tmb () 65535 com> wrote:More often than not, the underlying issue is an empty element within the DT_RPATH header or equivalent. Sometimes it's not, but even in those cases, it is largely that one or more elements isn't qualifed (i.e. it doesn't start with /). The attached patch fixes this, by ignoring any elements of DT_RPATH, LD_LIBRARY_PATH that do not start with a /, and/or junking any use of dlopen where the filename is likewise unqualified. Won't this break stuff?FWIW, relative RPATHs are quite fundamental to our test execution environment, and any patch that unconditionally ignores them would have to be reverted in our tree.
That's useful to know. Is that for setuid binaries or more generally? As I noted, it would be dead easy only to use the part of the patch that rejects them for the former only. Although as I said, that offers less protection. Would that make the patch more consumable? Another option would be to have something like /etc/suid-debug which could flag that an override is in operation.
Also, don't you want to discuss this on libc-alpha? oss-security could be all for it, but without buy-in from libc-alpha your patch is unlikely to be going anywhere.
I'm intending to, but getting security folk, who may well wear slightly more positive hats to begin with, to review it, seemed like a safe place to start. I can well imagine pursuading the glibc folk will be more difficult :/. Tim -- Tim Brown <mailto:tmb () 65535 com>
Attachment:
signature.asc
Description: This is a digitally signed message part.
Current thread:
- Fixing the glibc runtime linker Tim Brown (Feb 19)
- Re: Fixing the glibc runtime linker Stuart Gathman (Feb 19)
- Re: Fixing the glibc runtime linker Tim Brown (Feb 19)
- Re: Fixing the glibc runtime linker Paul Pluzhnikov (Feb 19)
- Re: Fixing the glibc runtime linker Tim Brown (Feb 19)
- Re: Fixing the glibc runtime linker Paul Pluzhnikov (Feb 19)
- Re: Fixing the glibc runtime linker Rich Felker (Feb 19)
- Re: Fixing the glibc runtime linker Paul Pluzhnikov (Feb 19)
- Re: Fixing the glibc runtime linker Rich Felker (Feb 19)
- Re: Fixing the glibc runtime linker Paul Pluzhnikov (Feb 20)
- Re: Fixing the glibc runtime linker Tim Brown (Feb 20)
- Re: Fixing the glibc runtime linker Rich Felker (Feb 20)
- Re: Fixing the glibc runtime linker Paul Pluzhnikov (Feb 20)
- Re: Fixing the glibc runtime linker Rich Felker (Feb 20)
- Re: Fixing the glibc runtime linker Tim Brown (Feb 19)
- Re: Fixing the glibc runtime linker Stuart Gathman (Feb 19)