upstream: Hash challenge supplied by client during FIDO key enrollment

prior to passing it to libfido2, which does expect a hash.

There is no effect for users who are simply generating FIDO keys using
ssh-keygen - by default we generate a random 256 bit challenge, but
people building attestation workflows around our tools should now have
a more consistent experience (esp. fewer failures when they fail to
guess the magic 32-byte challenge length requirement).

ok markus@

OpenBSD-Commit-ID: b8d5363a6a7ca3b23dc28f3ca69470472959f2b5
This commit is contained in:
djm@openbsd.org 2021-05-31 06:48:42 +00:00 committed by Damien Miller
parent eb68e669bc
commit 59a194825f
1 changed files with 9 additions and 4 deletions

View File

@ -1,4 +1,4 @@
/* $OpenBSD: sk-usbhid.c,v 1.29 2021/02/18 02:15:07 djm Exp $ */
/* $OpenBSD: sk-usbhid.c,v 1.30 2021/05/31 06:48:42 djm Exp $ */
/*
* Copyright (c) 2019 Markus Friedl
* Copyright (c) 2020 Pedro Martelletto
@ -669,7 +669,7 @@ sk_enroll(uint32_t alg, const uint8_t *challenge, size_t challenge_len,
{
fido_cred_t *cred = NULL;
const uint8_t *ptr;
uint8_t user_id[32];
uint8_t user_id[32], chall_hash[32];
struct sk_usbhid *sk = NULL;
struct sk_enroll_response *response = NULL;
size_t len;
@ -721,8 +721,13 @@ sk_enroll(uint32_t alg, const uint8_t *challenge, size_t challenge_len,
skdebug(__func__, "fido_cred_set_type: %s", fido_strerr(r));
goto out;
}
if ((r = fido_cred_set_clientdata_hash(cred, challenge,
challenge_len)) != FIDO_OK) {
if (sha256_mem(challenge, challenge_len,
chall_hash, sizeof(chall_hash)) != 0) {
skdebug(__func__, "hash challenge failed");
goto out;
}
if ((r = fido_cred_set_clientdata_hash(cred, chall_hash,
sizeof(chall_hash))) != FIDO_OK) {
skdebug(__func__, "fido_cred_set_clientdata_hash: %s",
fido_strerr(r));
goto out;