[Openvpn-users] Re: OpenSSL / OpenVPN / Padlock anomaly with small blocks of data.

[Michal Ludvig <michal@xxxxxxxx>]

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Rolf Fokkens wrote:

> Using the VIA Advanced Encryption Engine (ACE, Padlock) with OpenSSL
> seems to work fine, except for small blocks of data, as may be
> illustrated by the following OpenVPN execution.
> [...]
> This is just a test run, but without the padlock engine no error shows
> up. Actually using OpenVPN with padlock works very well, except for
> small packets caused by the "ping" option.
> [...]
> Slowing down the ebove test process by intruducing printf's of usleep's
> in the test loop solves the problem. Given this fact I changed the
> OpenSSL padlock code instead of the OpenVPN code to reproduce this
> solution, and guess what: IT WORKS! Look at the following diff:

Rolf,

I have never seen this kind of problem neither in userspace (OpenSSL)
nor in the kernel (CryptoAPI) where the execution can't be interrupted.

Actually I wasn't able to reproduce it with your test case neither (just
tried in SuSE Linux 9.2 with OpenVPN 2.0-rc20 and OpenSSL openssl-0.9.7d
with PadLock patch).

I guess there might be a problem with your CPU - what model/stepping
have you got? Or perhaps a miscompilation of either OpenSSL or OpenVPN?

Michal Ludvig
- --
* Personal homepage: http://www.logix.cz/michal



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