Proposal to reduce anti-bundling requirements

[Michael Stahl]

On 15.09.2015 15:58, Simo Sorce wrote:
> On Tue, 2015-09-15 at 09:41 -0400, Carlos O'Donell wrote:
>> On 09/14/2015 08:29 AM, Florian Weimer wrote:

>>> I think the real issue here is the ELF model with backwards/forwards
>>> linking and symbol interposition.  Ideally, we should load each DSO
>>> exactly once, resolve object symbols only against explicit DT_NEEDED
>>> dependencies (not indirect dependencies), and make most symbols
>>> non-interposable by default.  At least this is my gut feeling.  This is
>>> a very difficult problem, especially at distribution scale.
>>
>> I'm not sure how difficult this would be because I'm not sure how many
>> symbols rely upon indirect dependencies. I think it would be a worthwhile
>> cleanup to turn on something like you suggest, and attempt to bootstrap
>> the OS using Fedora Bootstrap [1].
> 
> 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.

by my naive count we have 341k exported symbols in LibreOffice, and of
those, 4 of them used to be interposeable in a practically useful way
(to override the custom memory allocator for valgrind), but even those
are useless nowadays since the G_SLICE environment variable disables the
custom allocator.