tree 87118ebdf8527ae7e1eddc4dad78078373bc6d21
parent 1a118bbf76ab52698961a1c7ec717ab0080b037d
author David Benjamin <davidben@google.com> 1707581288 -0500
committer Boringssl LUCI CQ <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com> 1709849966 +0000

Add an SSL_CREDENTIAL API for ECDSA/RSA and delegated credentials

This adds a notion of "credentials" to BoringSSL's API, to support
certificate selection by key type (typically ECDSA vs RSA), though the
aim is for it to be generalizable to other certificate types and other
kinds of selection criteria, such as Trust Expressions, or Merkle Tree
Certificates. Since we already had some nascent delegated credentials
I've reworked that feature with SSL_CREDENTIALs as well.

The model is that you create an SSL_CREDENTIAL object containing all the
configuration for what you are authenticating as. An X.509
SSL_CREDENTIAL has a certificate chain, private key, optionally an OCSP
response and SCT list. Delegated credentials are similar. In the future,
we might use this for raw public keys, other certificate types, etc.
Once you set those up, you configure those on the SSL or SSL_CTX in
preference order, and BoringSSL will internally pick the first one that
is usable.

The current implementation ends up redundantly selecting the signature
algorithm a couple of times. This works but is a little goofy. A
follow-up change will remove this redundancy. The protocol between the
runner and shim for tests is also a little weird, but it was the easiest
way I could think of for injecting that. Long-term, I think we should
just replace that protocol with a JSON structure. (See
https://crbug.com/boringssl/704.)

As split handshakes are in the process of being replaced with handshake
hints, this won't work with split handshakes. It works with handshake
hints without any extra work.

Update-Note: The delegated credentials API has been revamped.
Previously, it worked by configuring an optional delegated credential
and key with your normal certificate chain. This has the side effect of
forcing your DC issuer and your fallback certificate to be the same. The
SSL_CREDENTIAL API lifts this restriction.

A delegated credential is now just a different kind of credential. It
may use the same certificate chain as an X.509 credential or be
completely separate. All the SSL_CREDENTIAL APIs take CRYPTO_BUFFERs,
so, if common, the buffers may be shared to reduce memory.

The SSL_delegated_credential_used API is also removed, in favor of the
more general SSL_get0_selected_credential API. Callers can use ex_data
or pointer equality to identify the credential.

Bug: 249
Change-Id: Ibc290df3b7b95f148df12625e41cf55c50566602
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/66690
Reviewed-by: Bob Beck <bbe@google.com>
Commit-Queue: David Benjamin <davidben@google.com>