Thread: How to configer the pg_hba record which the database name with "\n" ?

Hi all,

I've come across an issue within pg_hba configuration which it seems
cannot not set the record of a database name where there is a
newline(\n) in the name.

I created the database whihin psql like this:
create database "ab
cd";

I have tried all the following records, but seems not to work:
local "ab\ncd "user auth-method
local "ab\\\ncd "user auth-method
local "ab
cd "user auth-method

Does PostgreSQL 9.2's client authentication support to match the
database name with "\n" ?

Cheers
-- 
--------------------------------------------------
Hu Xiaoming
MAIL : huxm@cn.fujitsu.com
--------------------------------------------------

huxm wrote
>  where there is a
> newline(\n) in the name.

I can't imagine why you would want to use non-printing characters in a name,
especially a database name.  Even if the hba.conf file was able to interpret
it (which it probably cannot but I do not know for certain) client
interfaces are likely to have problems as well.  Most of these would not
think of interpolating a database identifier in that manner but instead
treat the name as a literal value.  Even when line-continuations are allowed
they are often cosmetic in nature and the resultant newline is discarded
during the pre-execution phase of the command interpreter.

Arguably having a check constraint on the catalog to prohibit such a name
would be more useful than trying to make such a construct functional.

I'd guess in the immediate term the users accessing this database would need
to have "all" as their target and then you use role-based authorization to
limit which specific databases are accessible.

David J.





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On Thu, Aug  1, 2013 at 07:26:38AM -0700, David Johnston wrote:
> huxm wrote
> >  where there is a
> > newline(\n) in the name.
> 
> I can't imagine why you would want to use non-printing characters in a name,
> especially a database name.  Even if the hba.conf file was able to interpret
> it (which it probably cannot but I do not know for certain) client
> interfaces are likely to have problems as well.  Most of these would not
> think of interpolating a database identifier in that manner but instead
> treat the name as a literal value.  Even when line-continuations are allowed
> they are often cosmetic in nature and the resultant newline is discarded
> during the pre-execution phase of the command interpreter.
> 
> Arguably having a check constraint on the catalog to prohibit such a name
> would be more useful than trying to make such a construct functional.
> 
> I'd guess in the immediate term the users accessing this database would need
> to have "all" as their target and then you use role-based authorization to
> limit which specific databases are accessible.

I suppose the cleanest solution would be to allow a \n or a backslash
for line continuation, but I don't think pg_hba.conf supports those.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +

On 08/07/2013 04:12 PM, Bruce Momjian wrote:
> On Thu, Aug  1, 2013 at 07:26:38AM -0700, David Johnston wrote:
>> huxm wrote
>>>   where there is a
>>> newline(\n) in the name.
>> I can't imagine why you would want to use non-printing characters in a name,
>> especially a database name.  Even if the hba.conf file was able to interpret
>> it (which it probably cannot but I do not know for certain) client
>> interfaces are likely to have problems as well.  Most of these would not
>> think of interpolating a database identifier in that manner but instead
>> treat the name as a literal value.  Even when line-continuations are allowed
>> they are often cosmetic in nature and the resultant newline is discarded
>> during the pre-execution phase of the command interpreter.
>>
>> Arguably having a check constraint on the catalog to prohibit such a name
>> would be more useful than trying to make such a construct functional.
>>
>> I'd guess in the immediate term the users accessing this database would need
>> to have "all" as their target and then you use role-based authorization to
>> limit which specific databases are accessible.
> I suppose the cleanest solution would be to allow a \n or a backslash
> for line continuation, but I don't think pg_hba.conf supports those.
>


It doesn't. I really think this comes into the category of "don't do 
that!" The most we should do is document the pain that names with 
embedded newlines can cause.

cheers

andrew