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Tobias Urdin [Tue, 6 Feb 2024 07:50:55 +0000 (07:50 +0000)]

rgw/auth: ignoring signatures for HTTP OPTIONS calls

Before [1] we always sent all HTTP OPTIONS requests to
the S3AnonymousEngine and ignored any provided AWSv4
credentials sent in the request.

That PR changed so that if we got credentials in the
request we instead sent it through the authentication
code in order to solve HTTP OPTIONS requests on tenanted
users to start working (because we need to resolve the
tenant, also called bucket tenant in the code, and we can't
only rely on the bucket name since it will not be found).

We solved this by modifying the canonical HTTP method used
when calculating the AWSv4 signature by instead using the
access-control-request-method header which worked good.

This change did not take into account that when you generated
a presigned URL for a put_object request you can also pass in
extra parameters like a canned ACL [2] to the Params variable
in for example boto3's generated_presigned_url().

Doing that will cause the client to add the x-amz-acl header
to x-amz-signedheaders and also use that in their signature
calculation.

When doing a HTTP OPTIONS calls for CORS on that presigned URL
the browser will never send a x-amz-acl header with the correct
data since that is something that the actual PUT request should
include later, so that HTTP OPTIONS call should pass even though
the signature can never be calculated correctly server-side like
verified against AWS S3 in tracker [3].

This patch as a result skips the signature calculation when doing
EC2 auth using the LocalEngine but we still need to pass the request
there in order to lookup the user to support buckets in a tenant.

For the Keystone EC2 auth we're pretty out of luck in the sense that
Keystone's API itself requires us to send the AWSv4 signature in the
request with the access_key in order to obtain a token, and we cannot
leave the signature out, we also cannot spoof the signature from
rgw -> keystone since we don't have access to the secret_key if it's
not in our cache.

For that approach we simply pass on to get_access_token() that if it's
an HTTP OPTIONS and we find the access_key in the cache we pull that
and ignore verifying signature and pass it on for validation. This means
that the cache must be warm if using Keystone auth and adding extra
params to a presigned URL.

This partly makes some of the commits in [1] redundant for EC2
LocalEngine auth but we still need it for tenanted bucket support.

[1] https://github.com/ceph/ceph/pull/52673
[2] https://docs.aws.amazon.com/AmazonS3/latest/userguide/acl-overview.html#canned-acl
[3] https://tracker.ceph.com/issues/64308

Fixes: https://tracker.ceph.com/issues/64308
Signed-off-by: Tobias Urdin <tobias.urdin@binero.se>
(cherry picked from commit fe15b52edb5d228d2ed56679c62cf48493ae2d54)

Conflicts: no optional_yield argument in quincy
src/rgw/rgw_auth_keystone.cc
src/rgw/rgw_auth_keystone.h