upstream: support for user-verified FIDO keys

FIDO2 supports a notion of "user verification" where the user is
required to demonstrate their identity to the token before particular
operations (e.g. signing). Typically this is done by authenticating
themselves using a PIN that has been set on the token.

This adds support for generating and using user verified keys where
the verification happens via PIN (other options might be added in the
future, but none are in common use now). Practically, this adds
another key generation option "verify-required" that yields a key that
requires a PIN before each authentication.

feedback markus@ and Pedro Martelletto; ok markus@

OpenBSD-Commit-ID: 57fd461e4366f87c47502c5614ec08573e6d6a15

1 files changed, 3 insertions, 2 deletions

diff --git a/ssh-agent.c b/ssh-agent.c
index 5f7ac8b91..d24a63089 100644
--- a/ssh-agent.c
+++ b/ssh-agent.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-agent.c,v 1.262 2020/07/05 23:59:45 djm Exp $ */
+/* $OpenBSD: ssh-agent.c,v 1.263 2020/08/27 01:06:18 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -407,9 +407,10 @@ process_sign_request2(SocketEntry *e)
                             sshkey_type(id->key), fp);
                 }
         }
+        /* XXX support PIN required FIDO keys */
         if ((r = sshkey_sign(id->key, &signature, &slen,
             data, dlen, agent_decode_alg(key, flags),
-            id->sk_provider, compat)) != 0) {
+            id->sk_provider, NULL, compat)) != 0) {
                 error("%s: sshkey_sign: %s", __func__, ssh_err(r));
                 goto send;
         }