ossl(4) contains an implementation of AES-GCM for amd64. This implementation did not properly implement some aspects of the OCF interface. In particular, ossl(4) AES-GCM sessions were not thread-safe, and did not handle an AAD buffer outside of the main plaintext/ciphertext buffer. The former bug affects consumers which dispatch multiple requests in parallel on a single session, such as ZFS when encrypted datasets are configured. External AAD buffers are used by some network features such as ktls(4).
