On 07.05.2021 21:40, Nick Humrich wrote:
> PEP 501 was deferred because more learning and time was wanted after introducing
> f-strings. Now that it has been 5 years, I wonder what the possibilities of
> revisiting PEP 501 are.
>
> I recently had the experience of using javascript "tagged template literals" and
> was able to build a SQL string parser that is impossible to have SQL injection
> with. This is done by having the database connection object only accept a
> certain type of object, and all sql tagged template literals become that object.
> Because variables are lazy evaluated, the template function can turn all dynamic
> inputs into parameters in a SQL query. It is impossible for a dev to
> accidentally add a user imputed string as a literal.
> PEP 501 already mentions how templates (i-strings?) can solve injection. This is
> a very incredible goal. Injection has been the #1 vulnerability on OWASP for
> over 10 years, and has been in the top 5 the entire time OWASP has existed
> (almost 20 years now).
> We have an opportunity to completely remove injection attacks.
I think you ought to not use SQL injection as the primary argument
for i-strings.
The DB API highly recommends passing any arguments
to a SQL to the database via binding parameters and let the database
do the binding of the SQL template on the server side.
Sending those SQL templates and the parameters separately to the
database is not only safer, but also a lot more efficient and allows
for the database to much better manage query plan caching and reuse.
Interesting. When you do that in Python, does that mean something like %s in the SQL query, and then after the query a list of arguments in the same order as the %s tokens? Because if that's the case, maybe it'll be better to use an i-string there, and NOT have the Python layer format the string, but use that i-string to send the parameters separately to the database. It might be easier to read that way.
Even with i-strings we should *not* recommend doing the binding
of SQL strings in the Python application.
There are other use cases where lazy binding can be useful, though,
e.g. when you don't know whether the interpolation will actually
get used (logging) or where you may want to render the template
in a different or extended namespace.
--
Marc-Andre Lemburg
eGenix.com
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