Enhancement: increase SecPcreMatchLimit for specific file

[Orgoth]

Is there a way to increase the SecPcreMatchLimit for a specific file?
Our Application has an API which receives very large amounts of data and I only want to increase the limit for this API.
The global limit should stay the same.

[airween]

Hi @Orgoth,

which version do you use?

If you use libmodsecurity3 and Nginx, you should try to put into a location block:

    location /api/endpoint {
        modsecurity_rules '
          SecPcreMatchLimit 1024
        ';
    }

See this part of documentation.

[Orgoth]

Sorry forgot to mention.
I am using libapache2-mod-security2 2.9.3-3+deb11u2.

I suspect, I can create a files block within the vhost and set the rule for this specific file.
Thank you very much.

[airween]

Please feel free to close this issue if you could solve that.

[Orgoth]

Sadly, this is not possible.

SecPcreMatchLimit not allowed in <Location> context
SecPcreMatchLimit not allowed in <FilesMatch> context
SecPcreMatchLimit not allowed in <Directory> context
ModSecurity: SecPcreMatchLimit not allowed in VirtualHost

[Orgoth]

I will disable modsecurity via exclude rule for this api, the coworker confirmed, he will take responsibility.

But could this behavior be changed?
That you allow Apache in the module/lib that this rule can be set in the VHOST?

https://github.com/owasp-modsecurity/ModSecurity/tree/v2/master

Or is this something you do not have control and can not be changed within the module, to tell apache, it is allowed within the vhost?

[airween]

I'm not sure if it's possible - @marcstern what do you think?

[marcstern]

It's currently a global setting, but nothing would forbid to set it at the location level, as the value is used in each msc_pregcomp_ex() individually.

[Orgoth]

but nothing would forbid to set it at the location level

How to do so?

[marcstern]

I mean we could implement a change in the code