On 22/07/2019 17:44, Lynch, Andrew wrote:
> Hi,
>
> I am wondering whether it is ok to update a key's ex data from within an
> engine method that is using the key. This is with both OpenSSL 1.1.1a and
> 1.0.2j.
>
> In my engine's load_privkey() method I connect to the HSM and obtain handles
> for a session and the key object. Both handles are then stored in the key's
> ex data using RSA_set_ex_data() or EC_KEY_set_ex_data(). They will later be
> released by the registered free_func. The sign and/or encrypt methods use
> these handles when making their calls to the HSM API.
>
> This works fine for single operations like an openssl x509 command line, but
> not for long running applications such as stunnel. It appears that stunnel
> loads all configured keys and certs at startup and then waits for clients to
> connect. If there is no activity for a while the HSM will time out my
> session handle and the next sign operation using that session fails. I can
> catch the error and reconnect, but this results in a new session handle. The
> next time a client calls the same service, that key's ex data still contains
> the old outdated session handle resulting in the same error all over again.
>
> So whenever I renew a session handle in the sign method I need to update the
> ex data of the affected key with the new value.
>
> This appears to work fine for EC keys by calling EC_KEY_set_ex_data() from
> within the engine's ecdsa_do_sign() method. The same goes for RSA keys in
> rsa_private_decrypt() and rsa_private_encrypt(), but with rsa_sign() I have a
> problem in that the key parameter is const RSA *.
>
> Is the lack of const in rsa_private_encrypt() and ecdsa_do_sign() an
> oversight and I should not be manipulating ex data of the provided key in
> this way?
> Or is the const in rsa_sign() too strict and it is actually ok to modify the
> ex data of the key?
I can't see a problem with modifying the ex_data like that.
Matt
