1987: Enhancement to the rate limits r=mergify[bot] a=nextgens
## What type of PR?
enhancement
## What does this PR do?
Turn the rate-limiters into something useful (that won't fire for no reason).
- fix rate-limiting on /webdav/
- it changes the rate-limiting behaviour from limiting a single IP address to a subnet of a reasonable size (/24 on v4 and /56 on v6 both are now configurable) : AUTH_RATELIMIT_IP / AUTH_RATELIMIT_IP_V4_MASK / AUTH_RATELIMIT_IP_V6_MASK
- It ensures we only use IP-based rate-limits for attempts on accounts that do not exist
- it creates a new rate limit preventing attackers from targetting a specific user account (separate from what's above) : AUTH_RATELIMIT_USER
- it introduces a rate limiting exemption mechanism whereby, upon authentication, users will see their source-ip address being exempt for a specific amount of time AUTH_RATELIMIT_EXEMPTION_LENGTH. A similar mechanism is available for web-based sessions (see below)
- It introduces in AUTH_RATELIMIT_EXEMPTION a comma separated list of network CIDRs that will be exempt from both types of rate limiting
- it implements device-tokens, as described on https://owasp.org/www-community/Slow_Down_Online_Guessing_Attacks_with_Device_Cookies to ensure that genuine users aren't locked-out by a malicious attacker abusing the rate-limit feature.
Things that could be improved include:
- the IP-based rate limiter flags attempts against "non-existing" accounts: it could go further and flag the number of unique non-existing accounts attempted (to prevent the case of a user making a typo in his MUA configuration)
- the IP address exemption mechanism doesn't pin the exemption to a specific username: any real user can trivially bypass the rate limits (and attempt to brute-force someone else's account)
### Related issue(s)
- close#1926
- close#1745
- close#1915
## Prerequisites
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.
- [x] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/workflow.html#changelog) entry file.
Co-authored-by: Florent Daigniere <nextgens@freenetproject.org>
Co-authored-by: Diman0 <diman@huisman.xyz>
Co-authored-by: Florent Daigniere <nextgens@users.noreply.github.com>
Florent Daigniere