GitHub user hanm opened a pull request:
https://github.com/apache/zookeeper/pull/118
ZOOKEEPER-1634: hardening security by teaching server to enforce client
authentication.
## Motivation
Previously ZooKeeper server is open to the world as the server does not
enforce client authentication - anonymous clients are allowed to establish
session with server. This behavior raises a couple of issues from the
perspective of performance and security for example:
* It is easy to launch a DDoS attack to server, by having a fleet of
anonymous clients connect to the ensemble, as each session would consume
valuable resources (socket, memory, etc) from server.
* It is cumbersome to enforce certain security models with the presence of
anonymous clients login - for example as clients are not trusted the root ACL
has to be disabled for writes to world, among other configurations an admin has
to do to secure a cluster in a multi-tenant environment.
So the goal here is to address such issue by hardening ZooKeeper security
to provide a more confined access option that user could opt-in, which in
addition to the existing ACLs together could lead to more secured / resource
optimal ensemble.
## Design Abstract
* Introduce a new server side Java property that if set, ZooKeeper server
will only accept connections and requests from clients that have authenticated
with server via SASL.
* Clients that are not configured with SASL authentication, or configured
with SASL but fail authentication (i.e. with invalid credential) will not be
able to establish a session with server. A typed error code (-124) will be
delivered in such case, both Java and C client will close the session with
server thereafter, without further attempts on retrying to reconnect.
* This feature overrules the server property
"zookeeper.allowSaslFailedClients". So even if server is configured to allow
clients that fail SASL authentication to login, client will not be able to
establish a session with server if this feature is enabled.
* Only support SASL because only SASL authentication has the property that
no operations will happen until SASL authentication process finished. Thus, the
decision of whether to close the session or not can be quickly made on server
side upon receiving a client connection request. We could later add support for
other auth scheme via add_auth_info if that's desired (if we do, then a session
has to be maintained until add_auth_info is invoked.).
* As a side benefit, this PR fixes an issue mentioned in ZOOKEEPER-2346 by
correctly propagate events from server to client side so a SASL auth failure
will manifest as an auth / config failure rather than generic ConnectionLoss
event.
JIRA: https://issues.apache.org/jira/browse/ZOOKEEPER-1634
The PR also covers (or part of):
https://issues.apache.org/jira/browse/ZOOKEEPER-2462
https://issues.apache.org/jira/browse/ZOOKEEPER-2526
https://issues.apache.org/jira/browse/ZOOKEEPER-2346
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/hanm/zookeeper ZOOKEEPER-1634
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/zookeeper/pull/118.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #118
----
commit 90beaa0396cb2238b40e4b93764bd1a396b9047b
Author: Michael Han <h...@cloudera.com>
Date: 2016-11-29T23:19:38Z
ZOOKEEPER-1634: teach server to enforce client authentication.
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