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From "Alexander Shorin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (COUCHDB-1838) Specifying public_fields parameter discloses all user docs
Date Thu, 18 Jul 2013 02:00:50 GMT

    [ https://issues.apache.org/jira/browse/COUCHDB-1838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13711926#comment-13711926
] 

Alexander Shorin commented on COUCHDB-1838:
-------------------------------------------

[~rnewson], I have two ideas how to solve this problem:

1. Via special list function

What if we replace /_users/_all_docs resource internally will be not a system _all_docs view,
but a special list function that wraps this view?

I call list function special, because regular lists couldn't make any config lookups to get
list of public fields. Also, this special list function have always to call _all_docs view
with include_docs=true options, regardless the user request, but the returned result respects
the request query parameters.

I still call it list function because it acts as list function customizing view's result.

Previously you'd noted, that calling _all_docs view without include_docs=true parameter makes
impossible to lookup document stuff. So the big and only profit of this method is not to expose
internal CouchDB implementation "routines" outside. 


2. Special design document

More tricky and complex solution: there is special design document with special view function
that emits results only for documents with public fields. The view's code autoupdates after
each public_fields option change.

Problems: 
- additional view index; 
- need to cleanup public_fields values to prevent code injections ; 
- stale=ok ruins everything ;

But it worth to try.

                
> Specifying public_fields parameter discloses all user docs
> ----------------------------------------------------------
>
>                 Key: COUCHDB-1838
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-1838
>             Project: CouchDB
>          Issue Type: Bug
>            Reporter: Alexander Shorin
>
> When public_fields are specified it's possible to retrieve all available user docs, no
matter does they contains specified public fields or not.
> 0. Setup some users:
> {code}
> curl -X PUT http://localhost:5984/_users/org.couchdb.user:abc -d '{"name":"abc", "roles":[],
"type":"user", "password": "cba"}'  -H "Content-Type: application/json"  
> curl -X PUT http://localhost:5984/_users/org.couchdb.user:def -d '{"name":"def", "roles":[],
"type":"user", "password": "fed"}'  -H "Content-Type: application/json" 
> {code}
> 1. Check the old behavior without public_fields:
> {code}
> curl -v http://abc:cba@localhost:5984/_users/_all_docs
> HTTP/1.1 403 Forbidden
> Server: CouchDB/1.4.0+build.8d7ab8b (Erlang OTP/R16B)
> Date: Fri, 21 Jun 2013 23:12:13 GMT
> Content-Type: text/plain; charset=utf-8
> Content-Length: 87
> Cache-Control: must-revalidate
> {"error":"forbidden","reason":"Only admins can access _all_docs of system databases."}
> {code}
> 2. Specify some public fields that no one actually has:
> {code}
> curl -X PUT http://localhost:5984/_config/couch_httpd_auth/public_fields -d '"no_user_will_never_has_ziz_field_in_his_doc"'
-H "Content-Type: application/json" --user couch_admin
> {code}
> 3. Try step 1 one more time:
> {code}
> curl -v http://abc:cba@localhost:5984/_users/_all_docs
> HTTP/1.1 200 OK
> Transfer-Encoding: chunked
> Server: CouchDB/1.4.0+build.8d7ab8b (Erlang OTP/R16B)
> ETag: "55N0CA8VM2Z0DQO85L1PM20XS"
> Date: Fri, 21 Jun 2013 23:15:05 GMT
> Content-Type: text/plain; charset=utf-8
> Cache-Control: must-revalidate
> {"total_rows":6,"offset":0,"rows":[
> {"id":"_design/_auth","key":"_design/_auth","value":{"rev":"1-619db7ba8551c0de3f3a178775509611"}},
> {"id":"org.couchdb.user:abc","key":"org.couchdb.user:abc","value":{"rev":"1-64d299987b4df59c048171a8ab8ba951"}},
> {"id":"org.couchdb.user:def","key":"org.couchdb.user:def","value":{"rev":"1-479a3e8a66652838706cc49544730a34"}},
> {"id":"org.couchdb.user:foo","key":"org.couchdb.user:foo","value":{"rev":"1-3859ee3742314dcb4b4f1ffaba398c91"}},
> {"id":"org.couchdb.user:mia","key":"org.couchdb.user:mia","value":{"rev":"1-f87f5003323e705d8c7a533cdd0a267c"}},
> {"id":"org.couchdb.user:root","key":"org.couchdb.user:root","value":{"rev":"1-f43dadbe5e780f392a6bd283686b3704"}}
> ]}
> {code}
> Same for anonymous user:
> {code}
> curl -v http://localhost:5984/_users/_all_docs
> HTTP/1.1 200 OK
> Transfer-Encoding: chunked
> Server: CouchDB/1.4.0+build.8d7ab8b (Erlang OTP/R16B)
> ETag: "55N0CA8VM2Z0DQO85L1PM20XS"
> Date: Sat, 22 Jun 2013 00:04:17 GMT
> Content-Type: text/plain; charset=utf-8
> Cache-Control: must-revalidate
> {"total_rows":6,"offset":0,"rows":[
> {"id":"_design/_auth","key":"_design/_auth","value":{"rev":"1-619db7ba8551c0de3f3a178775509611"}},
> {"id":"org.couchdb.user:abc","key":"org.couchdb.user:abc","value":{"rev":"1-64d299987b4df59c048171a8ab8ba951"}},
> {"id":"org.couchdb.user:def","key":"org.couchdb.user:def","value":{"rev":"1-479a3e8a66652838706cc49544730a34"}},
> {"id":"org.couchdb.user:foo","key":"org.couchdb.user:foo","value":{"rev":"1-3859ee3742314dcb4b4f1ffaba398c91"}},
> {"id":"org.couchdb.user:mia","key":"org.couchdb.user:mia","value":{"rev":"1-f87f5003323e705d8c7a533cdd0a267c"}},
> {"id":"org.couchdb.user:root","key":"org.couchdb.user:root","value":{"rev":"1-f43dadbe5e780f392a6bd283686b3704"}}
> ]}
> {code}
> The problem is that with specified public_fields it's possible to retrieve all user's
names no matter has their public field or not. This behaviour a bit violates implemented [System
Database Security|https://git-wip-us.apache.org/repos/asf?p=couchdb.git;a=commit;h=e5503ff]:
> [CouchDB 1.2.0 release notes|https://blogs.apache.org/couchdb/entry/apache_couchdb_1_2_0]:
> {quote}
> Documents in the _users database can no longer be read by everyone
> Documents in the _users databases can now only be read by the respective authenticated
user and administrators. Before, all docs were world-readable including their password hashes
and salts.
> {quote}
> [Security Features Overview|http://wiki.apache.org/couchdb/Security_Features_Overview#Authentication%20database]:
> {quote}
> In addition, the _users database is now treated different from other databases:
>     An anonymous user can only create a new document.
>     An authenticated user can only update their own document.
>     A server or database admin can access and update all documents.
>     Only server or database admins can create design documents and access views and _all_docs
and _changes. 
> {quote}
> Expected behaviour when `public_fields` specified:
> `_all_docs` should returns only those user docs, that are actually contains public fields.
Users that has no such fields has nothing to publish. If user doc has public fields it shouldn't
be mentioned in `_all_docs` response.

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