Re: New password hashing scheme as plugin

2 Aug 2016


      2016-08-01 15:58 GMT+02:00 aki.tuomi@dovecot.fi:
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On August 1, 2016 at 4:38 PM aki.tuomi@dovecot.fi wrote:
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On August 1, 2016 at 3:45 PM Andreas Meyer luckyfellow42@gmail.com
wrote:
2016-07-31 16:39 GMT+02:00 aki.tuomi@dovecot.fi:
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On July 27, 2016 at 2:08 AM Andreas Meyer 
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wrote:
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Hi,
I want to add a new password hashing scheme as plugin and provide
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the dovecot project, so that it will be included as optional
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future releases.
Yet the plugin compiles fine and the .so file gets created.
My approach is to call the functions password_scheme_register() and
password_scheme_unregister() (src/auth/password-scheme.c) inside
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plugin's _init() and _deinit() functions.
When a client tries to login via imap the log shows an error
message:
Error: Couldn't load required plugin
/usr/local/lib/dovecot/lib20_newauth_plugin.so: dlopen() failed:
/usr/local/lib/dovecot/lib20_newauth_plugin.so: undefined symbol:
password_scheme_unregister
That error obviously occurs, because the required lib is not
it for
plugin in
the
linked into
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the plugin.
Now my problem is to understand, whether this approach (via .so
file) can
be successful at all and if so, how?
Do I need to link libs into it? Which would that be and how do I
specify
them in the Makefile.am?
I assume, I don't need to link a lib, but need to use a hook to
register
the new hashing scheme, since the plugin is loaded into an already
existing
process, which needs to get extended. If this is true, which hook
would
that be and how do I register the new scheme?
Or is there no way to accomplish this via a separated .so plugin?
Should
I
extend the sources in /src/auth instead? (separat file for the
hashing
scheme with preprocessor instructions to include it only on demand)
Thank you very much,
Andreas
Can you publish your code in, say, github.com and provide link to
it?
New password scheme is doable as plugin but it needs to placed in
different
place and it will be autoloaded.
Aki
I created two branches. Both compile fine with the option:
--with-libsodium
Branch #1)
https://github.com/LuckyFellow/dovecot-core-libsodium/tree/2.2.25_libsodium_...
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This is my try to add libsodium support as plugin. When the plugin is
loaded, it exits with the mentioned error message "undefined symbol:
password_scheme_unregister"
Branch #2)
https://github.com/LuckyFellow/dovecot-core-libsodium/tree/2.2.25_libsodium_...
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This compiles fine and also works. The new hashing schemes SCRYPT and
ARGON2 are available to dovecot.
Libsodium support is not created as module, but only added if the
--with-libsodium option was passed to configure.
Regards,
Andreas
Hi!
I had a look at your code and noticed you had tried to put it in
dovecot's tree. I would recommend making completely separate plugin of it.
It's not very hard, I can help you out there. It does not need to be in
src/plugins, the source supports fully external plugins that you can then
install separately.
This would make it lot more easier to develop the plugin. I'll see if I
can make you a little skeleton to help you out with this, you can then use
it as basis for your auth plugin.
Aki
https://github.com/cmouse/dovecot-password-scheme-plugin
is the plugin template you can use. please see if it helps you out.
Aki
Thank you very much for the skeleton. It really helped a lot.
I created this repository and checked in my changes:
https://github.com/LuckyFellow/dovecot-libsodium-plugin
It compiles and installs fine. The auth module loads the plugin
automatically on demand, the hashing schemes are available and they work.
What do I need to do, so that you can include it as plugin?
Regards,
Andreas