Fix EC public key export for provider keys

[anurag6569201]

Most of the explanation for this change is documented as comments in this pull request. However, before:

.NET 11.0.0-preview.6.26359.118
Unhandled exception. System.Security.Cryptography.CryptographicException: Error occurred during a cryptographic operation.
   at Interop.Crypto.EvpPKeyGetEcKeyParameters(SafeEvpPKeyHandle key, Boolean includePrivate)
   at System.Security.Cryptography.ECOpenSsl.ExportNamedCurveParametersFromEvpPKeyUsingParams(SafeEvpPKeyHandle pkey, String curveName, Boolean includePrivateParameters)
   at System.Security.Cryptography.X509Certificates.ECDsaCertificateExtensions.CopyWithPrivateKey(X509Certificate2 certificate, ECDsa privateKey)
   at Program.<Main>$(String[] args) in /home/vcsjones/ecdsa-pkcs11-repro/HsmPoc/Program.cs:line 17

After:

.NET 11.0.0-dev
Subject: CN=hsm-poc
Has private key: True
Public X: 1AE3DAFDDE6536E1FC23C7227ABA86E5A9F678BFBBF74674A0A75D29CDDB5770
Public Y: 97FB07F101E2E07D7D4828E3EB3C33B5B6DE4060CFA3D9EE9FF703700FFFA136
Signature valid: True

The general gist of the change is the the PKCS#11 OpenSSL provider does not "materialize" the public key until you go through an export KEYMGMT interface:

https://github.com/openssl-projects/pkcs11-provider/blob/c7a5c8b62a0ff012b16574f01651254ef7e664ee/src/kmgmt/common.c#L496-L498

Attempting to directly export the public key before this materialization happens results in an error.

We continue to try out existing way first - this is both performance and works in scenarios where a Provider has not implemented KEYMGMT APIs. If it fails, we attempt with EVP_PKEY_todata, which gives us the public key through a KEYMGMT API. It uses the same OSSL_PARAM OSSL_PKEY_PARAM_PUB_KEY as we were using before, so we can use the same point handling for the existing and fallback way.

Contributes to dotnet#133171

Source merge-base: 75cffcef7186a6a0b738f15a98d0b28c6c8e6507
Source head: 56562651f2f82b31d86d2869b922ee2e7b9bc834

[shipwright-agent]

⛔ Shipwright · Blocked

Recommendation: do not merge PR #13 · Tier T1
Checks: 0 total · 0 needing attention

Next step: resolve the blocking findings before merge.

Findings (3)

• CRITICAL The fallback path calls OSSL_PARAM_free(exportedParameters) unconditionally at exit, but exportedParameters is only initialized to NULL at declaration and only assigned by EVP_PKEY · src/native/libs/System.Security.Cryptography.Native/pal_ecc_import_export.c:867
  • Fix: Review the cited evidence, fix the risk if confirmed, and rerun Shipwright.
• CRITICAL The fallback path uses OSSL_PARAM_get_octet_string_ptr to obtain a pointer to the public key data and then passes it to EC_POINT_oct2point without copying. · src/native/libs/System.Security.Cryptography.Native/pal_ecc_import_export.c:814
  • Fix: Review the cited evidence, fix the risk if confirmed, and rerun Shipwright.
• HIGH The control flow uses a goto label public_key_exported that is placed after the fallback block, but the label is inside the function and the fallback block is conditionally compile · src/native/libs/System.Security.Cryptography.Native/pal_ecc_import_export.c:767
  • Fix: Review the cited evidence, fix the risk if confirmed, and rerun Shipwright.

Fireworks usage: 10,277 input · 709 output · 10,986 total tokens · $0.0027 · 11s · 0 fix iteration(s)

Open the Shipwright check for full evidence and the audit bundle. Use /shipwright rerun to verify again.

[shipwright-agent]

Shipwright · CRITICAL

The fallback path calls OSSL_PARAM_free(exportedParameters) unconditionally at exit, but exportedParameters is only initialized to NULL at declaration and only assigned by EVP_PKEY

Impact: The fallback path calls OSSL_PARAM_free(exportedParameters) unconditionally at exit, but exportedParameters is only initialized to NULL at declaration and only assigned by EVP_PKEY_todata. If EVP_PKEY_todata succeeds but returns a non-NULL pointer, this is fine; however, if the function is entered via the public_key_exported goto after the EVP_PKEY_get_octet_string_param path, exportedParameters remains NULL and OSS…

Suggested fix: Review the cited evidence, fix the risk if confirmed, and rerun Shipwright.

[shipwright-agent]

Shipwright · HIGH

The control flow uses a goto label public_key_exported that is placed after the fallback block, but the label is inside the function and the fallback block is conditionally compile

Impact: The control flow uses a goto label public_key_exported that is placed after the fallback block, but the label is inside the function and the fallback block is conditionally compiled with FEATURE_DISTRO_AGNOSTIC_SSL. On builds without FEATURE_DISTRO_AGNOSTIC_SSL, the fallback block is absent, but the goto public_key_exported from the first path still compiles because the label is present. This creates a confusing con…

Suggested fix: Review the cited evidence, fix the risk if confirmed, and rerun Shipwright.