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Date: Wed, 29 Nov 2023 08:45:49 -0500
From: Carlos O'Donell <carlos@...hat.com>
To: musl@...ts.openwall.com, Fangrui Song <i@...kray.me>,
Eleanor Bartle <eleanor@...anor-nb.com>
Cc: Markus Wichmann <nullplan@....net>
Subject: Re: Care about Symbol Namespacing?
On 11/28/23 00:17, Fangrui Song wrote:
> GNU symbol versioning is actually a system that provides the import
> file information: vn_file. However, glibc rtld does not utilize
> vn_file to speed up symbol searches. In addition,
>
>> https://maskray.me/blog/2020-11-26-all-about-symbol-versioning#version-script
>> vn_file is essentially ignored for symbol search since glibc 2.30
>> https://sourceware.org/bugzilla/show_bug.cgi?id=24741 . Previously
>> during relocation resolving, after an object failed to provide a
>> match, if it matched vn_file, rtld would report an error `symbol %s
>> version %s not defined in file %s with link time reference`.
This change in glibc was intentional. I agree with Rich here that static linking
should be treated as a first class feature and glibc has moved towards ensuring
that dynamic and static linking behaviour is more similar. The exception here is
that in glibc the goal will be to give developers the option to disallow
dlopen() from a statically linked application; thus providing the developer
assurances that nothing else will be loaded (important when crossing namespace
boundaries, particularly mount namespaces).
--
Cheers,
Carlos.
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