Re: Manage PostgreSQL Database for GITLAB Application?

Adrian Klaver <adrian.klaver@aklaver.com> writes:

> On 1/21/19 1:07 PM, Hilbert, Karin wrote:
> Please reply to list also.
> Ccing list.
>
>> Adrian,
>>
>>
>> You said:
>>
>> Would it not be easier to ask the application developer what his
>> permissions model is. I can see a game of Whack-a-Mole ahead otherwise.
>>
>>
>> I'm sorry, what do you mean by permissions model?
>
> What does the application enforce in the way of permissions on the database
> objects?
>
> The potential issue is the database being set up to run under one set of
> permissions rules and the application under another. This could lead to the
> application not running at all, secure but not useful:) From what has been
> posted so far I am betting that this problem is going to be have to be solved
> from both ends. It comes done to what balance of security and application ease
> of use is needed. That in turn depends on what the security guidelines are for
> your organization.
>
>>
>>
>>
>> In your first response to my post, you said:
>> Could you be more specific about the above?:
>>
>> 1) Are talking about installing GitLab as a self-managed server?
>> 2) Or an application that is running over top of GitLab?
>>
>> I don't know much about the application - I believe that Gitlab is a code
>> repository application.
>
> Yes it is. What I was trying to get at is whether this application you refer to
> is the stock one created by:
>
> https://about.gitlab.com/install/
>
> or is this some custom application over the GitLab install?
>
>>
>> I'm responsible for managing the database that supports Gitlab.
>>
>>
>> Regards, Karin
>>
>> ------------------------------------------------------------------------
>> *From:* Adrian Klaver <adrian.klaver@aklaver.com>
>> *Sent:* Monday, January 21, 2019 2:36:23 PM
>> *To:* Hilbert, Karin; Stephen Frost
>> *Cc:* pgsql-general@lists.postgresql.org
>> *Subject:* Re: Manage PostgreSQL Database for GITLAB Application?
>> On 1/21/19 11:23 AM, Hilbert, Karin wrote:
>>> Thanks Stephen,
>>>
>>>
>>> I'm under the gun to get this database restored & then tested with the
>>> application.
>>>
>>> I'll try changing the schema back from public to the original schema (the
>>> same as the application user account name).  If that doesn't work for the
>>> application, then I'll try leaving the schema as public.
>>
>> Would it not be easier to ask the application developer what his
>> permissions model is. I can see a game of Whack-a-Mole ahead otherwise.
>>
>>>
>>> I'll definitely remove the statements revoking privileges from the dbowner
>>> & change the grant statements back to the application account instead of
>>> PUBLIC.
>>>
>>>
>>> The only access to the database is from the gitlab application (I guess
>>> that's what you mean by "I'd definitely have the database be dedicated to
>>> gitlab.")
>>>
>>>
>>> I make the developer have his application connect in with the application
>>> user account for normal operations.  When his application undergoes an
>>> upgrade, it needs to also be able to update the database.  I always made
>>> him connect with the dbowner account for this & then switch the connection
>>> back the application user account when the upgrade was done.
>>>
>>>
>>> Thanks for confirming my thoughts about public.  I was starting to second
>>> guess myself.
>>>
>>>
>>> May I also ask your thoughts regarding something else for the gitlab
>>> database?
>>>
>>> We have two instances; one for development & one for production.  When we
>>> originally created the databases, we had separate names for the database,
>>> schema & application user:
>>>
>>>
>>> dbname_dev/dbname_prod
>>>
>>> sname/snamep
>>>
>>> username/usernamep
>>>
>>>
>>> The other year, we had to restore the prod database backup to dev & that
>>> changed the schema name.  I was thinking that it would be better have the
>>> same names used for dev & prod so that restores from one environment to
>>> another would be easier.  (That's a standard that our DBA team employs for
>>> our SQL Server databases.)  Does it make sense to also employ that standard
>>> for PostgreSQL databases?  Is there any reason to keep the names different
>>> between the environments?
>>>
>>>
>>> Thanks again for your help.
>>>
>>> Regards,
>>>
>>> Karin
>>>
>>> ------------------------------------------------------------------------
>>> *From:* Stephen Frost <sfrost@snowman.net>
>>> *Sent:* Monday, January 21, 2019 1:53:00 PM
>>> *To:* Hilbert, Karin
>>> *Cc:* pgsql-general@lists.postgresql.org
>>> *Subject:* Re: Manage PostgreSQL Database for GITLAB Application?
>>> Greetings,
>>>
>>> * Hilbert, Karin (ioh1@psu.edu) wrote:
>>>> Does anyone manage a PostgreSQL database for a GITLAB application?
>>>
>>> Yes.
>>>
>>>> I have PostgreSQL v9.6 installed on my server & we are trying to migrate a GITLAB database there.
>>>>
>>>> The developer says that we need to use the public schema instead of the schema of the same name as the application
user.
>>>
>>> Not sure this is really required but it also shouldn't hurt anything
>>> really- I'd definitely have the database be dedicated to gitlab.
>>>
>>>> The schema that he provided me to restore also is revoking all privileges from the database owner & instead
grantingall privileges to PUBLIC.
 
>>>
>>> That's terrible.
>>>
>>>> Has anyone else run across this?  I always thought that granting privileges to PUBLIC is a bad security thing to
do?
>>>
>>> Yes, that's bad from a security perspective and shouldn't be necessary.
>>> GRANT rights to the user(s) the application logs into, don't just grant
>>> them to PUBLIC- that would allow anyone on the system to have access.
>>>
>>>> If anyone can offer any thoughts regarding this, it would be greatly appreciated.
>>>
>>> Is this developer the only one who is going to be using this gitlab
>>> instance..?  Sounds like maybe they want direct database access which
>>> would only make sense if they're the one running it and should have full
>>> access- but even then, I'd create a role and grant access to that role
>>> and then grant them that role, if that's the requirement.  GRANT'ing
>>> things to public isn't a good idea if you're at all concerned about
>>> security.
>>>
>>> Thanks!
>>>
>>> Stephen
>>
>>
>> --
>> Adrian Klaver
>> adrian.klaver@aklaver.com

Joining discussion late, so apologise in advance if I repeat information
already provided.

Just wanted to mention that unfortunately, there are some libraries out
there which provide a layer of abstraction for working with databases
and postgres in particular, but which do not handle database schemas at
all well. I'm not defending or criticising such libraries, but want to
point out that sometimes, a developer, who is required to use specific
libraries or modules, may not have the freedom to fully use the power of
database schemas and that sometimes, limitations/restrictions are not
necessarily at the DB level. As DBA's we need to recognise such
restrictions exist, even if they seem misguided. As an example, there
have been issues with at least one of the commonly used db interface
libs/modules used by the Javascript SAILS framework (which I believe was
addressed in later versions) that made working with different schemas
very difficult.

I would agree that the description provided regarding changes to
permissions does raise concerns and hints of a developer under pressure
to make something work with insufficient understanding of the
underlying DB security and access control model. It is likely the
developer needs guidance in this area.

I also would argue that the PUBLIC schema is not in itself a security
risk. The problem is with inappropriate use of that schema. It depends
heavily on how the database is used. A database used for a single
application has a completely different security and risk profile from a
database used by multiple users for different applications. Arbitrary
rules such as 'you won't use PUBLIC' are almost always wrong and often
just make both developer and dba lives more complicated and harder to
maintain. Complexity is where things go wrong and where security tends
to break down.

Rather than requiring the developer to use a specific schema, I would

1. Ask them why they believe they have to use the PUBLIC schema
2. If the need to use the PUBLIC schema is confirmed, then work with the
developer to understand what the access requirements are and develop an
appropriate model.
3. If there is no dependency on using the PUBLIC schema, work with the
developer to assist them to resolve there access issues.

Depending on the size of the organisation and complexity of the
environment, choice of libraries and modules is not always as
straight-forward. It may not be easy to switch to another library/module
with better support for schemas etc or even to upgrade to a new
version. Often, such changes will need to be managed in stages and over
time. Work with the developers as complex environments will frequently
require a united voice in order to get changes approved or prioritised.

Tim

--
Tim Cross