On 09/16/2015 03:47 PM, Dave Love wrote: > Michael Stahl <mstahl@xxxxxxxxxx> writes: > >>> Symbol interposition is used a lot for very useful features, blocking >>> interposition would break a lot of stuff. >> >> really? i've always thought that it was only useful for libc symbols, >> but maybe that's because i don't work on base OS stuff. > > I'd guess most uses are not to do with base OS stuff. It's important in > a lot of cases in research-type computing support, though that doesn't > seem to count for much. > > Profiling and other instrumentation in the high performance computing > world (where it's taken quite seriously) typically uses LD_PRELOAD > libraries. I think it is important to keep the LD_PRELOAD case separate from implicit interposition between the main program (if linked with -E) and DSOs or between different DSOs. LD_PRELOAD is quite explicit in what it wants to do. What I'm really interested in is a use case where something pulls in a library with DT_NEEDED and relies on predictable linking order to override a specific symbol. We have cases where this happens, but they all seem accidents to me. -- Florian Weimer / Red Hat Product Security -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
