nsswitch implementation

[Michael A. Bushkov]

Greetings!

We are currently working on alternate nsswitch implementation for
FreeBSD. We want to make this implementation more flexible and powerful
than the current one.

Our idea is to make 3-level structure of nsswitch:

1) libc functions talking to the level2 daemon

2) Special daemon (nssd) accepting queries from
libc, passing them to level3 (modules) and sending answers
back to libc

3) DSO modules, containing functions doing real work
to obtain requested information from any source or
database (for example nss_files.so, nss_dns.so and so on)

The daemon (level 2) should be able do dynamically open modules - we
can't call dlopen() directly from libc.

At the moment we have a working alpha-version of daemon, nss_files 
module and
some rewritten libc functions. And there is one problem: behaviour of 
modules
should be different for regular users and for root. Currently (in libc) 
this
is done with the help of geteuid(). This is not applicable for modules
since their function are called by the daemon but not the originating
process itself.

We see two implementable solutions:

1. Run 2 daemons to separate root and non-root queries.

2. Pass uid information to the module functions and let them use it 
instead of
geteuid()

And another 'theoretical' solution: to intersept geteuid() calls from 
modules.

We defenitely need some suggesions and discussion. Any help will be 
greatly
appreciated.

Pleas keep CC lines in replies since we're not on the list.

Michael A. Bushkov
Computer Center of Rostov State University