Re: [ANN] SE-PostgreSQL 8.2.3-1.0 alpha release

[KaiGai Kohei <kaigai@kaigai.gr.jp>]

Stephen Smalley wrote:
> On Wed, 2007-03-07 at 04:05 +0900, KaiGai Kohei wrote:
>>>> * There is no compatibility between SE-PostgreSQL and PostgreSQL.
>>>>   You have to pay attention not to destroy your database files
>>>>   for native PostgreSQL.
>>> Have you considered enabling "permissive mode" for the database server such 
>>> that it can run with unlabeled databases?
>>>
>>> Why can't "native PostgreSQL" just ignore the labelling?
>> We have to store a security context of tuple in anywhere, so modifying the file
>> format was not avoidable. The storage manager of PostgreSQL cannot handle different
>> file formats, so SE-PostgreSQL cannot run over the unlabeled databased generated
>> by native PostgreSQL.
>>
>> It might be possible, but I expect more hooks to the PostgreSQL is necessary.
>> It will prevent to follow the version-up of native one.
> 
> Do they provide any kind of attribute / metadata support at that
> granularity?  Along the lines of filesystem xattrs?

Any kind of database objects (like tables, columns) are stored as tuples within
special tables called as system catalog, so I think that associating a security
context with a tuple provides enough granularity.
# The meaning of your question was a bit unclear for me.
# If my response is miss the point, please tell me.

> Could you store the labels in a separate table?  Along the lines of the
> old persistent label mapping in SELinux (issues for consistency and
> performance, of course).

I think unique identification for all tuples are difficult, because we can
create a table without Oid (object id) or primary key to identify a tuple
from outside of the table...

BTW, the string representations of security contexts are stored in a separate
table named as 'pg_selinux', defined with Oid (which have 4-byte length).
In SE-PostgreSQL, any tuples have Oid of pg_selinux as a security context.
Thus, storage consumption is limited.

> Could you split the storage from the presentation such that you only
> store data of one context in a given underlying table and then compose a
> set of single context tables to present a multi-context virtual table?
--
KaiGai Kohei <kaigai@kaigai.gr.jp>

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