topic problem with shl_load and pam in Operating System - HP-UX

problem with shl_load and pam

Bj_5 — Tue, 20 Aug 2002 19:26:09 GMT

Hello!

I try to port a self-written PAM module from Linux to HP-UX 11.00. The problem is, that i have to use some LDAP-functions from an third-party library (IBM SecureWay for HP-UX). Building a standalone-program with them works fine, but when compiled and linked as a shared library it gives the well-known error: Can't shl_load() a library containing Thread Local Storage: /usr/lib/libpthread.1

I've read a lot of stuff about that error and i've tried almost everything that was ever suggested...

I read, that libpthread must be loaded before that library to avoid the problem. So i've tried to link against "-lpthread" too, but no effect. I also tried a lot of combinations, including -ldld, -lc and so on. Nothing. I don't know any further now.

I would use the LD_PRELOAD feature too, but where to set an environment variable for the PAM-environment?

Here the output from "odump -sllibloadlist" for that module, if it helps:

0 libpam_test.1
1 ^ /usr/lib/libibmldap.sl
2 ^ ^ /usr/lib/libc.2
3 ^ ^ ^ /usr/lib/libdld.2
4 ^ ^ /usr/lib/libpthread.1

Is it right, that the load direction ist bottom up? So if libpam_test.1 should be loaded it would be: libpthread, libdld, libc, libibmldap?

Anyone able to help?

Many thanks in advance!!

Bjoern

Re: problem with shl_load and pam

Mike Stroyan — Wed, 21 Aug 2002 14:06:41 GMT

The only way to make libpthread.1 work in your shared library would be to have it linked into all a.outs that use your shared library. That is not practical with a PAM module.
(It is also really dangerous to think about introducing threading into a bunch of code that was not written or compiled as thread-safe.)
The simplest fix for your problem is to create a small a.out that your shared library communicates with to access the libibmldap.sl functions. You could either fork/exec that a.out for every startup of your shared library, or leave a daemon process that your library can connect to as needed. The best fit will depend on the performance and security requirements of your design.

Re: problem with shl_load and pam

Bj_5 — Thu, 22 Aug 2002 08:37:38 GMT

That would be a solution. I think i will try it that way.

Thanks,
Bjoern