ceph/doc/radosgw/s3/authentication.rst

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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.
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: http://en.wikipedia.org/wiki/HMAC