ceph/doc/radosgw/s3/authentication.rst
Florian Haas d730820a48 Improve OpenStack integration and multitenancy docs for radosgw
Add explanatory information on:

* "rgw swift account in url" (including the Swift account in the Swift
  API url and Keystone endpoint)
* "rgw swift versioning enabled" (enabling Swift object versioning)
* "rgw s3 auth use keystone" (enabling S3 authentication against
  Keystone)
* "rgw keystone implicit tenants" (multi-tenancy via Keystone, including
  its implications for the Swift and S3 APIs)

Fixes: http://tracker.ceph.com/issues/36765
Signed-off-by: Florian Haas <florian@citynetwork.eu>
2018-12-19 17:46:56 +01:00

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=========================
Authentication and ACLs
=========================
Requests to the RADOS Gateway (RGW) can be either authenticated or
unauthenticated. RGW assumes unauthenticated requests are sent by an anonymous
user. RGW supports canned ACLs.
Authentication
--------------
Authenticating a request requires including an access key and a Hash-based
Message Authentication Code (HMAC) in the request before it is sent to the
RGW server. RGW uses an S3-compatible authentication approach.
::
HTTP/1.1
PUT /buckets/bucket/object.mpeg
Host: cname.domain.com
Date: Mon, 2 Jan 2012 00:01:01 +0000
Content-Encoding: mpeg
Content-Length: 9999999
Authorization: AWS {access-key}:{hash-of-header-and-secret}
In the foregoing example, replace ``{access-key}`` with the value for your access
key ID followed by a colon (``:``). Replace ``{hash-of-header-and-secret}`` with
a hash of the header string and the secret corresponding to the access key ID.
To generate the hash of the header string and secret, you must:
#. Get the value of the header string.
#. Normalize the request header string into canonical form.
#. Generate an HMAC using a SHA-1 hashing algorithm.
See `RFC 2104`_ and `HMAC`_ for details.
#. Encode the ``hmac`` result as base-64.
To normalize the header into canonical form:
#. Get all fields beginning with ``x-amz-``.
#. Ensure that the fields are all lowercase.
#. Sort the fields lexicographically.
#. Combine multiple instances of the same field name into a
single field and separate the field values with a comma.
#. Replace white space and line breaks in field values with a single space.
#. Remove white space before and after colons.
#. Append a new line after each field.
#. Merge the fields back into the header.
Replace the ``{hash-of-header-and-secret}`` with the base-64 encoded HMAC string.
Authentication against OpenStack Keystone
-----------------------------------------
In a radosgw instance that is configured with authentication against
OpenStack Keystone, it is possible to use Keystone as an authoritative
source for S3 API authentication. To do so, you must set:
* the ``rgw keystone`` configuration options explained in :doc:`../keystone`,
* ``rgw s3 auth use keystone = true``.
In addition, a user wishing to use the S3 API must obtain an AWS-style
access key and secret key. They can do so with the ``openstack ec2
credentials create`` command::
$ openstack --os-interface public ec2 credentials create
+------------+---------------------------------------------------------------------------------------------------------------------------------------------+
| Field | Value |
+------------+---------------------------------------------------------------------------------------------------------------------------------------------+
| access | c921676aaabbccdeadbeef7e8b0eeb2c |
| links | {u'self': u'https://auth.example.com:5000/v3/users/7ecbebaffeabbddeadbeefa23267ccbb24/credentials/OS-EC2/c921676aaabbccdeadbeef7e8b0eeb2c'} |
| project_id | 5ed51981aab4679851adeadbeef6ebf7 |
| secret | ******************************** |
| trust_id | None |
| user_id | 7ecbebaffeabbddeadbeefa23267cc24 |
+------------+---------------------------------------------------------------------------------------------------------------------------------------------+
The thus-generated access and secret key can then be used for S3 API
access to radosgw.
.. note:: Consider that most production radosgw deployments
authenticating against OpenStack Keystone are also set up
for :doc:`../multitenancy`, for which special
considerations apply with respect to S3 signed URLs and
public read ACLs.
Access Control Lists (ACLs)
---------------------------
RGW supports S3-compatible ACL functionality. An ACL is a list of access grants
that specify which operations a user can perform on a bucket or on an object.
Each grant has a different meaning when applied to a bucket versus applied to
an object:
+------------------+--------------------------------------------------------+----------------------------------------------+
| Permission | Bucket | Object |
+==================+========================================================+==============================================+
| ``READ`` | Grantee can list the objects in the bucket. | Grantee can read the object. |
+------------------+--------------------------------------------------------+----------------------------------------------+
| ``WRITE`` | Grantee can write or delete objects in the bucket. | N/A |
+------------------+--------------------------------------------------------+----------------------------------------------+
| ``READ_ACP`` | Grantee can read bucket ACL. | Grantee can read the object ACL. |
+------------------+--------------------------------------------------------+----------------------------------------------+
| ``WRITE_ACP`` | Grantee can write bucket ACL. | Grantee can write to the object ACL. |
+------------------+--------------------------------------------------------+----------------------------------------------+
| ``FULL_CONTROL`` | Grantee has full permissions for object in the bucket. | Grantee can read or write to the object ACL. |
+------------------+--------------------------------------------------------+----------------------------------------------+
.. _RFC 2104: http://www.ietf.org/rfc/rfc2104.txt
.. _HMAC: https://en.wikipedia.org/wiki/HMAC