Re: Paypal and "going root"

Richard Huxton wrote:
> Kenneth Downs wrote:
>> The last one left that I have is the sticky issue of a paypal IPN
>> transaction coming in.  I believe it applies generally to financial
>> transactions.  The user is sent by our application to the Paypal
>> site.  When they pay, paypal sends a POST with various information
>> that we need.  The user does not see this, it is behind the scenes.
>> The POST request must run as an anonymous user because I have no
>> state whatsoever.  But the request must also commit financial data.
>> This creates a vulnerability, at least in theory.
>
> Well, your POST will be authenticating as some sort of PG user,
> presumably. Give it its own account and make sure the only permissions
> it has is to insert into the paypal_rcpt table (or call a function
> that does it for you). Obviously it will only connect from the
> webserver(s) and only from the apache user account (or IIS/whatever).
> So, you can use the ~/.pgpass password file to keep that password
> protected.
>
I think this is the answer that I need.  This goes to the heart of how
the user connects to PG.  The key concept that I'm taking away from your
answer is that instead of connecting as a powerful user, connect as a
severely limited user who can do only one thing: make that insert.  The
rest should be conducted from there.

I can put some rules on the receipts table that require the row to
contain various hashes and verification codes obtained from the invoice
table, and the user who inserts to this table must have no ability to
read any other table in the system, so they cannot obtain the codes by
any means.  In converse, I believe normal users should not be able to
read or write this table, it would be completely invisible to your
average Joe.


--
Kenneth Downs
Secure Data Software, Inc.
www.secdat.com    www.andromeda-project.org
631-689-7200   Fax: 631-689-0527
cell: 631-379-0010