Re: [tpm2] dlopen()'ing raw .so files considered bad

[Philip Tricca <philip.b.tricca at intel.com>]

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On Thu, May 31, 2018 at 09:12:45PM +0000, Roberts, William C wrote:
> 
> 
> > -----Original Message-----
> > From: tpm2 [mailto:tpm2-bounces(a)lists.01.org] On Behalf Of Trevor Woerner
> > Sent: Thursday, May 31, 2018 1:47 PM
> > To: tpm2(a)lists.01.org
> > Subject: [tpm2] dlopen()'ing raw .so files considered bad
> > 
> > Hey everyone,
> > 
> > I was playing around with the latest tpm2 tools (i.e. the git master) and I noticed
> > that this code is now dlopen()'ing the libraries at runtime.
> > 
> > That's a very nice feature, but the way it's been implemented is not entirely
> > correct.
> > 
> > The filename parameter to dlopen() should be a library's SONAME, not the raw
> > .so file. The raw .so file is considered a -dev or -devel package component, not a
> > component of the library package itself. The raw .so exists as a develop crutch,
> > but shouldn't be used in production.
> > 
> > The raw .so will always point to the latest shared library object. But in an ideal
> > world, the shared library's API should be denoted by the first number after ".so.".
> > It would be extremely unlikely that the programs linking to today's TSS (with its
> > current API) would continue to work should an API-breaking change occur in the
> > future (thus requiring the first number after ".so." to be incremented).
> 
> Per the spec we work on, we can't break it.
> 
> > 
> > In other words, programs should dlopen() a specific API (e.g. ".so.0") and not just
> > "the latest" (i.e. ".so").
> 
> Good to know, well make this change in the tools:
> https://github.com/tpm2-software/tpm2-tools/pull/1052

Have one up for tabrmd as well:
https://github.com/tpm2-software/tpm2-abrmd/pull/471

Philip

> > 
> > Please see https://lists.debian.org/debian-policy/2002/12/msg00041.html, for
> > example.
> > 
> > As is, this is going to mess up people packaging this software for various distros,
> > and users trying to use this software (since they'll have to install the -dev
> > packages for it to work, which can get messy for non-developer users).
> > 
> > 
> > Thanks and best regards,
> >     Trevor
> 
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