[FILEUPLOAD-297] Default maximum sizes for requests and files

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Flags: Patch
• Assignee: Jochen Wiedmann
• Reporter: Artem Smotrakov
• Created: 05/Apr/19 16:16
• Updated: 27/May/20 10:43
• Resolved: 27/May/20 10:43

Description

Currently FileUpload allows setting the maximum allowed size of a complete request and the maximum allowed size of a file to be uploaded. However the library doesn't set any default limitations. Introducing default values may be a little defense-in-depth measure to reduce a risk of (D)DoS attacks for applications which forgot to set such limits.

Here is how other libraries/servers set such default values:

1. nginx sets the maximum allowed size of the client request body to 1MB
   1. http://nginx.org/en/docs/http/ngx_http_core_module.html#client_max_body_size
2. By default, the IIS 7 upload limit is 30MB
   1. https://docs.microsoft.com/en-us/windows/desktop/bits/upload-limits
3. PHP sets max size of post data allowed to 8MB. PHP also sets the maximum size of an uploaded file to 2MB
   1. https://www.php.net/manual/en/ini.core.php#ini.post-max-size
   2. https://www.php.net/manual/en/ini.core.php#ini.upload-max-filesize
4. Spring Boot specifies the maximum size permitted for uploaded files. The default is 1MB. It also specifies the maximum size allowed for multipart/form-data requests. The default is 10MB.
   1. https://docs.spring.io/spring-boot/docs/current/api/org/springframework/boot/autoconfigure/web/servlet/MultipartProperties.html

As you can see, default values look pretty different. I am attaching a patch which sets the maximum file size to 2MB and the maximum size of a request to 10MB. Adding such limits by default introduces a risk that some applications may break, so maybe the numbers should be higher. Please let me know if such an update is okay, and I'll create a pull request.