Kenneth Downs wrote:
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.
Ah, that's exactly what I was trying to say. Apologies if I phrased it
badly, but you seem to have the gist anyway.
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.
You might want to allow inserts and have a "validated" flag that you can
check. Failing that, make sure you log the values on a failed insert -
always useful to have an audit trail if there are problems.
--
Richard Huxton
Archonet Ltd
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