PKCS11 tokens that don't support RSA-PSS don't work. We should make sure the mechanism is supported or handle the error

[fliot]

Hi, first of all, congrats to committers, Ghostunnel is a very nice piece of software !

I had, very different and very explicit error messages until I found out the correct pkcs11 parameters (certificate, token label, etc...),
But I'm still facing issues trying to handle mTLS Client tunnel, based on HSM & PKCS11 token.

ghostunnel client 
    --listen localhost:8080 
    --target my.remote.service:443 
    --override-server-name my.remote.service
    --cert my-certificate-as-extracted-from-the-hsm-token.cer 
    --pkcs11-module my_pkcs11.dll 
    --pkcs11-token-label "token-label" 
    --pkcs11-pin 1234

[816] 2023/01/31 19:37:30.399578 starting ghostunnel in client mode
[816] 2023/01/31 19:37:30.400616 using PKCS#11 module as certificate source
[816] 2023/01/31 19:37:31.246722 using target address my.remote.service:443
[816] 2023/01/31 19:37:31.247721 listening for connections on localhost:8080
[816] 2023/01/31 19:37:33.773976 error on dial: pkcs11key: sign init: pkcs11: 0x70: CKR_MECHANISM_INVALID

My HSM token, seems to effectively provide signing for CKM_SHA256_RSA_PKCS or CKM_RSA_PKCS (just in case you were wondering...)

Any idea ?
Thanks in advance.

[mcpherrinm]

Is the pkcs11 DLL provided by your HSM vendor? Are you willing to share what vendor that is?

There's no flag for this, but I wonder if it has to do with RSA-PSS in TLS1.3. Do you know if the server you're connecting to supports TLS1.3?

If you've got any Go experience, can you try adding a MaxVersion: tls.TlsVersionTLS12 around here: https://github.com/ghostunnel/ghostunnel/blob/master/tls.go#L115 and see if that works?

Otherwise we might have to add a bit of debugging to log what parameters it's unhappy with.

[fliot]

Hi,
Thanks for your feedback,
Indeed, with this

MaxVersion:               tls.VersionTLS12,
Renegotiation: tls.RenegotiateOnceAsClient,

I got some success, and definitively TLS1.3 is blocking, due to my HSM/pkcs11 DLL functions.
Great thanks for your support.

[mcpherrinm]

I'm going to keep this open as a bug, as it would be reasonable to support these tokens but limited to TLS 1.2, or at least produce a better error message