This bug requires manual review: We are only 11 days from stable.
Please contact the milestone owner if you have questions.
Owners: amineer@(Android), kariahda@(iOS), cindyb@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

(For merge reviewers) The upshot of this bug is a severe violation of user privacy. Relying Parties should not be able to query, without user consent, whether a device does or does not contain a known credential. This can let a malicious RP identify a user via probing.

https://w3c.github.io/webauthn/#sec-assertion-privacy

crrev.com/c/1185220 is not in canary yet, pls update bug with canary result tommrow. Also how safe is the change to merge to M69 this late in release cycle?

The NextAction date has arrived: 2018-08-24

How is the change looking in canary so far?

The change made it into canary today. 

It's a safe change that only affects security key devices that return a certain type of error code in response to a request for which the device doesn't have a matching credential. We tested this scenario on affected devices this morning in Canary, and it now shows the behavior that we intended to achieve with the change. 

Approving merge for crrev.com/c/1185220  to M69 branch 3497 based on comments #3 and #8.

Merge to M69 has been landed in https://chromium.googlesource.com/chromium/src/+/36eaaa643f3076f5b80b83f2516760a39799c8aa.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/36eaaa643f3076f5b80b83f2516760a39799c8aa

commit 36eaaa643f3076f5b80b83f2516760a39799c8aa
Author: Martin Kreichgauer <martinkr@google.com>
Date: Mon Aug 27 16:25:41 2018

[M69] device/fido: fix an issue in authenticator error response handling

1) Change FidoRequestHandler to not terminate a WebAuthn request when a
request handler replies with the CTAP2_ERR_INVALID_CREDENTIAL or
CTAP2_ERR_CREDENTIAL_NOT_VALID CTAP2 error codes. These error codes do
not indicate that the user has interacted with the authenticator and
we therefore must not resolve the  WebAuthN request promise upon
receiving such an error.

2) Remove kCtap2ErrCredentialNotValid since
CTAP2_ERR_CREDENTIAL_NOT_VALID has recently been dropped from the CTAP2
spec.

3) Change references to kCtap2ErrCredentialNotValid in U2F code to
kCtap2ErrNoCredentials in order to not change behavior of that code with
regards to request canceling.

(cherry picked from commit 52f4995e5f4c3db27916274d20bc54aa78db13b7)

Bug:  877226 
Change-Id: Ied8dd2c8b4af939d6b922c0007520b90d3a92388
Reviewed-on: https://chromium-review.googlesource.com/1185220
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Reviewed-by: Kim Paulhamus <kpaulhamus@chromium.org>
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Reviewed-by: Jun Choi <hongjunchoi@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#585575}
Reviewed-on: https://chromium-review.googlesource.com/1189183
Cr-Commit-Position: refs/branch-heads/3497@{#814}
Cr-Branched-From: 271eaf50594eb818c9295dc78d364aea18c82ea8-refs/heads/master@{#576753}
[modify] https://crrev.com/36eaaa643f3076f5b80b83f2516760a39799c8aa/device/fido/fido_constants.h
[modify] https://crrev.com/36eaaa643f3076f5b80b83f2516760a39799c8aa/device/fido/fido_request_handler.h
[modify] https://crrev.com/36eaaa643f3076f5b80b83f2516760a39799c8aa/device/fido/get_assertion_task_unittest.cc
[modify] https://crrev.com/36eaaa643f3076f5b80b83f2516760a39799c8aa/device/fido/u2f_sign_operation.cc
[modify] https://crrev.com/36eaaa643f3076f5b80b83f2516760a39799c8aa/device/fido/u2f_sign_operation_unittest.cc