upstream: preserve verify-required for resident FIDO keys

When downloading a resident, verify-required key from a FIDO token,
preserve the verify-required in the private key that is written to
disk. Previously we weren't doing that because of lack of support
in the middleware API.

from Pedro Martelletto; ok markus@ and myself

OpenBSD-Commit-ID: 201c46ccdd227cddba3d64e1bdbd082afa956517

sk-api.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: sk-api.h,v 1.9 2020/04/28 04:02:29 djm Exp $ */
+/* $OpenBSD: sk-api.h,v 1.10 2020/08/27 01:08:19 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -63,6 +63,7 @@ struct sk_resident_key {
 	size_t slot;
 	char *application;
 	struct sk_enroll_response key;
+	uint8_t flags;
 };
 
 struct sk_option {
@@ -71,7 +72,7 @@ struct sk_option {
 	uint8_t required;
 };
 
-#define SSH_SK_VERSION_MAJOR		0x00050000 /* current API version */
+#define SSH_SK_VERSION_MAJOR		0x00060000 /* current API version */
 #define SSH_SK_VERSION_MAJOR_MASK	0xffff0000
 
 /* Return the version of the middleware API */

sk-usbhid.c

@@ -1104,8 +1104,7 @@ read_rks(struct sk_usbhid *sk, const char *pin,
 			}
 
 			srk->key.key_handle_len = fido_cred_id_len(cred);
-			memcpy(srk->key.key_handle,
-			    fido_cred_id_ptr(cred),
+			memcpy(srk->key.key_handle, fido_cred_id_ptr(cred),
 			    srk->key.key_handle_len);
 
 			switch (fido_cred_type(cred)) {
@@ -1121,6 +1120,9 @@ read_rks(struct sk_usbhid *sk, const char *pin,
 				goto out; /* XXX free rk and continue */
 			}
 
+			if (fido_cred_prot(cred) == FIDO_CRED_PROT_UV_REQUIRED)
+				srk->flags |=  SSH_SK_USER_VERIFICATION_REQD;
+
 			if ((r = pack_public_key(srk->alg, cred,
 			    &srk->key)) != 0) {
 				skdebug(__func__, "pack public key failed");

ssh-sk.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-sk.c,v 1.30 2020/04/28 04:02:29 djm Exp $ */
+/* $OpenBSD: ssh-sk.c,v 1.31 2020/08/27 01:08:19 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -769,8 +769,9 @@ sshsk_load_resident(const char *provider_path, const char *device,
 		default:
 			continue;
 		}
-		/* XXX where to get flags? */
 		flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY;
+		if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD))
+			flags |= SSH_SK_USER_VERIFICATION_REQD;
 		if ((r = sshsk_key_from_response(rks[i]->alg,
 		    rks[i]->application, flags, &rks[i]->key, &key)) != 0)
 			goto out;