Prevent SQL Injection in DBI

Prevent SQL Injection in DBI

[Jakub Jankiewicz]

Hi all,

I want to use guile-dbi with unsafe user input. I have code like this:

(dbi-query db-obj (string-append "SELECT * FROM users WHERE username = '"
                                 username
                                 "'"))

How can I escape username given from user to prevent sql injection?

I could validate username to only contain letters using [a-zA-Z] regex but
what about other languages that have non Latin letters and names like O'Conor?
This will also don't work for password that may have special characters.

--
Jakub Jankiewicz, Web Developer
http://jcubic.pl

Re: Prevent SQL Injection in DBI

[Christopher Allan Webber]

Jakub Jankiewicz writes:

> Hi all,
>
> I want to use guile-dbi with unsafe user input. I have code like this:
>
> (dbi-query db-obj (string-append "SELECT * FROM users WHERE username = '"
>                                  username
>                                  "'"))
>
> How can I escape username given from user to prevent sql injection?
>
> I could validate username to only contain letters using [a-zA-Z] regex but
> what about other languages that have non Latin letters and names like O'Conor?
> This will also don't work for password that may have special characters.

guile-squee is pretty immature but I do think it does this one bit
correctly... parameters to the procedure shouldn't be substituted in the
string, they should be provided as additional arguments, like

  (exec-query db-obj "SELECT * FROM users WHERE username=$1"
              '("alice"))

I seem to remember trying to find out if this was possible to do in
dbi-query, and not succeeding at finding such a route?  (guile-dbi,
unlike guile-squee, has some maturity though...)

Re: Prevent SQL Injection in DBI

[Linas Vepstas]

I don't think guile-dbi does this safety check.  You are welcome to add it.

Since gna.org is dead, I moved everything over to
https://github.com/opencog/guile-dbi

--linas

On Mon, Mar 27, 2017 at 1:24 PM, Christopher Allan Webber <
cwebber@dustycloud.org> wrote:

> Jakub Jankiewicz writes:
>
> > Hi all,
> >
> > I want to use guile-dbi with unsafe user input. I have code like this:
> >
> > (dbi-query db-obj (string-append "SELECT * FROM users WHERE username = '"
> >                                  username
> >                                  "'"))
> >
> > How can I escape username given from user to prevent sql injection?
> >
> > I could validate username to only contain letters using [a-zA-Z] regex
> but
> > what about other languages that have non Latin letters and names like
> O'Conor?
> > This will also don't work for password that may have special characters.
>
> guile-squee is pretty immature but I do think it does this one bit
> correctly... parameters to the procedure shouldn't be substituted in the
> string, they should be provided as additional arguments, like
>
>   (exec-query db-obj "SELECT * FROM users WHERE username=$1"
>               '("alice"))
>
> I seem to remember trying to find out if this was possible to do in
> dbi-query, and not succeeding at finding such a route?  (guile-dbi,
> unlike guile-squee, has some maturity though...)
>
>