[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[bug#30386] [PATCH v2 cuirass] database: Prevent SQL injection.

From: Ludovic Courtès
Subject: [bug#30386] [PATCH v2 cuirass] database: Prevent SQL injection.
Date: Fri, 09 Feb 2018 17:05:34 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux)

Danny Milosavljevic <address@hidden> skribis:

>> optimization looks good, provided the extra conditions don’t make sqlite
>> slower.  
> Compared to parsing the SQL text again and again (which is dead slow), I think
> an extra NULL check *on the same field* is not going to matter at all.
> Even compared to using lots of main memory and thus not being able to use
> the processor's cache (if we had lots of prepared statements), I think an
> extra NULL check is still better :)
> Of course once we have a lot of data in the tables, the actual lookup costs
> will dwarf any setup costs.  Then still, it's checking the same field that's
> used anyway, so the extra cost should be neglible.

Sounds good, let’s do that then.

>> It might allow us to use ‘sqlite-exec’ directly, and thus
>> benefit from the binding support in there, as in:
>>   (sqlite-exec db "… WHERE " id " is NULL or …")
> I added sqlite-bind-arguments with keyword arguments specifically so 
> sqlite-exec
> doesn't suck.
> So it would be like (sqlite-exec db "SELECT … :a … :b … :a"
>                                     #:a 42
>                                     #:b 2)
> Before, it was:
> (sqlite-exec db "SELECT … ? … ? … ?"
>                 42
>                 2
>                 42)

Right, but now it’s as I wrote above: you can include arguments in the
middle of the SQL strings, and ‘sqlite-exec’ takes care of turning
that into question marks and so on:

Anyway, we can support both the keyword style you show above, and the
other thing I mention, and use whichever is most convenient for the code
at hand.

I find the ‘sqlite-exec’ convenient for simple cases where the query is
a literal, but the keyword style might be more convenient for complex
queries like ‘db-get-builds’.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]