improve the testing of credentials against inserted FIDO keys a little

more: ask the token whether a particular key belongs to it in cases
where the token support on-token user- verification (e.g. biometrics)
rather than just assuming that it will accept it.

Will reduce spurious "Confirm user presence" notifications for key
handles that relate to FIDO keys that are not currently inserted in at
least some cases.

Motivated by bz3366; by Pedro Martelletto

diff --git a/usr.bin/ssh/sk-usbhid.c b/usr.bin/ssh/sk-usbhid.c
index 95930b9..8deebf4 100644 (file)
--- a/usr.bin/ssh/sk-usbhid.c
+++ b/usr.bin/ssh/sk-usbhid.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sk-usbhid.c,v 1.35 2021/12/02 22:40:05 djm Exp $ */
+/* $OpenBSD: sk-usbhid.c,v 1.36 2021/12/02 23:23:13 djm Exp $ */
 /*
  * Copyright (c) 2019 Markus Friedl
  * Copyright (c) 2020 Pedro Martelletto
@@ -396,12 +396,14 @@ sk_select_by_cred(const fido_dev_info_t *devlist, size_t ndevs,
 {
        struct sk_usbhid **skv, *sk;
        size_t skvcnt, i;
+       int internal_uv;
 
        if ((skv = sk_openv(devlist, ndevs, &skvcnt)) == NULL) {
                skdebug(__func__, "sk_openv failed");
                return NULL;
        }
-       if (skvcnt == 1) {
+       if (skvcnt == 1 && check_sk_options(skv[0]->dev, "uv",
+           &internal_uv) == 0 && internal_uv != -1) {
                sk = skv[0];
                skv[0] = NULL;
                goto out;