upstream: translate and return error codes; retry on bad PIN

Define some well-known error codes in the SK API and pass
them back via ssh-sk-helper.

Use the new "wrong PIN" error code to retry PIN prompting during
ssh-keygen of resident keys.

feedback and ok markus@

OpenBSD-Commit-ID: 9663c6a2bb7a0bc8deaccc6c30d9a2983b481620

1 files changed, 6 insertions, 1 deletions

diff --git a/sk-api.h b/sk-api.h
index 4f9f43ee6..dc786d556 100644
--- a/sk-api.h
+++ b/sk-api.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sk-api.h,v 1.5 2019/12/30 09:23:28 djm Exp $ */
+/* $OpenBSD: sk-api.h,v 1.6 2019/12/30 09:24:45 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -32,6 +32,11 @@
 #define SSH_SK_ECDSA                    0x00
 #define SSH_SK_ED25519                  0x01
 
+/* Error codes */
+#define SSH_SK_ERR_GENERAL              -1
+#define SSH_SK_ERR_UNSUPPORTED          -2
+#define SSH_SK_ERR_PIN_REQUIRED         -3
+
 struct sk_enroll_response {
         uint8_t *public_key;
         size_t public_key_len;