Credential-less pulls of public images. /auth/token issues a pull-only
token with an empty subject when no Basic auth is present; the
destination hold still enforces captain.Public, and push or delete always
challenges.
- token.IsPullOnlyScope and AuthMethodAnonymous;
Handler.issueAnonymousToken skips the authorizer gate and the
service-auth pre-mint, since there is no identity to reconcile and no
AppView-to-hold service token to bind. The token is still stamped
with the resolved registry domain, so anonymous pull works on
secondary front doors whose access controller demands their own
audience.
- auth.allow_anonymous_pull (default true) turns it fully off, restoring
the previous always-challenge behavior. Mirrored into the deploy
template, since the default means existing deploys pick this up.
- RegistryContext.Anonymous is plumbed from the middleware.
- ProxyBlobStore sends no Authorization header when the service token is
empty, and returns 401 rather than 403 for anonymous denials so Docker
prompts for credentials, including when a stale captain cache lets the
request through and the hold says private.
- BearerChallenge wraps the /v2/ subtree so a 401 raised deep in the
stack via errcode.ServeJSON still carries WWW-Authenticate.
Distribution's own scoped challenges are left alone.
IsPullOnlyScope allowlists the pull action instead of denylisting push and
delete. Distribution's actionSet.contains treats "*" as *every* action, so
a scope of `repository:victim/img:*` names neither denied string and would
have handed an unauthenticated caller a token valid for push and delete on
someone else's repository — clearing the authgate entirely, since anonymous
tokens deliberately skip it. Writes would still have failed further down
(no PDS credential), but the gate itself was bypassable. Now every
requested action must be exactly "pull". Covered by new claims tests.
Unresolvable identities return NAME_UNKNOWN instead of a bare error that
distribution renders as 500. This path was previously unreachable without
credentials; anonymous pull opens it to the internet, and a 5xx on
arbitrary input both misreports a bad request as a server fault and sends
clients that retry 5xx into a retry loop. That loop was real: in the auth
matrix, regclient spent 83s on a single case before this fix, and the
suite now runs in 5s.
Stat preserves an authorization verdict from getPresignedURL rather than
flattening it to ErrBlobUnknown. Distribution calls Stat before ServeBlob
on GET and HEAD, so without this an anonymous pull from a private hold
answered 404 and BearerChallenge had no 401 to annotate — the 401 path
above could never actually reach a client.
The auth matrix is updated to match: anonymous pull of the seeded public
repo now succeeds, anonymous push is denied against a real identity's
namespace (rather than an unresolvable one, which was testing name
resolution rather than authorization), and a new case pins the
NAME_UNKNOWN behavior for an unknown identity.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The route was registered GET-only, so containerd and Docker, which try the
OAuth2 POST endpoint first whenever they hold a secret, ate a 405 and retried
on the GET form. Every authenticated pull paid two auth round trips, and in the
production logs the POST share of token traffic grew from 0.5% to 38% over six
weeks as more clients pulled from k8s with basic-auth imagePullSecrets.
Serve both specs on the same path. After credentials and scope are extracted
the two paths are identical, so this is an extraction branch plus a form-shaped
error writer.
Only grant_type=password is supported and no refresh token is issued: the
registry JWT's lifetime is pinned to the AppView<->hold service-auth, so a
refresh token would be a fourth long-lived credential with its own storage and
revocation. Clients handle its absence by continuing to use the credential they
already hold.
The refresh grant is refused with 401 rather than the 400 that RFC 6749 5.2
prescribes. containerd sends that grant only when it has no username, which is
the same condition that disables its 405 fallback, so a 400 would hard-fail
those clients. 401 is on its retry list and routes them to the GET form, where
a device secret authenticates off the password alone. That shape previously had
no working path at all.
resolveService now takes the requested service as an argument, since it arrives
in the query string on GET and in the form body on POST.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Evan JarrettandClaude Opus 5