Files
smallwebwaf/internal/proxy/bans.go
T
clawbot 163ce966ef
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Rule files, and bans for a clear sign of attack (closes #24)
Every *.rules file in SWWAF_RULES_DIR not named with a leading dot is
read at start, and again 2 seconds after the directory's last change.
Each request is checked against the rules after the rate limits: log
notes a match, block refuses with 403, ban refuses and bans the netblock
for SWWAF_ATTACK_BAN_DURATION, made permanent by its next request or
attack. path, query and uri are matched as the request line sent them;
header:Host and header:Transfer-Encoding are refused. Bans gain a cause.
The image ships 00-default.rules.

Judgement call: a header sent twice is matched with its values joined
by ", ".
Judgement call: SWWAF_MAX_BAN_DURATION does not cap a ban for an attack.
Not in this unit: offences for rule matches, with the error burst.

Model: opus-5-5
2026-10-06 18:20:02 +00:00

126 lines
3.4 KiB
Go

package proxy
import (
"net/netip"
"time"
"sneak.berlin/go/smallwebwaf/internal/bans"
"sneak.berlin/go/smallwebwaf/internal/requestlog"
"sneak.berlin/go/smallwebwaf/internal/rules"
)
// banResponse is a refusal answered with SWWAF_BAN_RESPONSE, and logged
// with action.
func (rq *request) banResponse(action string) *refusal {
return &refusal{status: rq.h.config.BanResponse, action: action}
}
// banned reports whether a ban on a netblock the client is in covers the
// request at now, and notes for the log line when that ban ends.
func (rq *request) banned(now time.Time) bool {
check := rq.h.ledger.Check
if rq.h.config.Observe {
check = rq.h.ledger.Find // in observe mode the ban refuses nothing
}
ban, banned := check(rq.client, now)
if banned {
rq.line.BanExpires = banExpires(ban)
}
return banned
}
// limitBroken counts the request for the rate limits at now, notes the
// client's counts for the log line, and reports whether the request takes
// the client over a limit. In enforce mode such a request bans the
// client's netblock, and sets the client's counters back to zero; in
// observe mode it does neither.
func (rq *request) limitBroken(now time.Time) bool {
group := clientGroup(rq.client)
counts, hit, over := rq.h.limiter.Count(group, now)
rq.line.Counts = counts
if !over {
return false
}
rq.line.LimitHit = hit.Window
rq.line.Offence = requestlog.OffenceLimit
if rq.h.config.Observe {
return true
}
netblock := rq.netblock()
ban := rq.h.ledger.BanForLimit(netblock, now, bans.Notes{
Country: rq.line.Country,
Limit: hit.Limit,
Window: hit.Window,
Count: hit.Requests,
Request: rq.noted(now),
Requests: rq.netblockRequests(netblock),
})
rq.h.limiter.Reset(group)
rq.line.BanExpires = banExpires(ban)
return true
}
// banForAttack bans the client's netblock at now for a clear sign of
// attack, the match of rule, a ban rule.
func (rq *request) banForAttack(now time.Time, rule rules.Rule) {
netblock := rq.netblock()
ban := rq.h.ledger.BanForAttack(netblock, now, bans.Notes{
Country: rq.line.Country,
RuleID: rule.ID,
Target: rule.Target,
Request: rq.noted(now),
Requests: rq.netblockRequests(netblock),
})
rq.line.BanExpires = banExpires(ban)
}
// noted is the request, refused at now with SWWAF_BAN_RESPONSE, as the
// notes of the ban it makes keep it.
func (rq *request) noted(now time.Time) bans.Request {
return bans.Request{
Time: now,
Method: rq.in.Method,
Host: rq.in.Host,
Path: rq.in.URL.RequestURI(),
Status: rq.h.config.BanResponse,
UserAgent: rq.in.UserAgent(),
}
}
// netblockRequests is how many requests netblock has sent since it was
// first seen, this one included: the histories count it only once it has
// ended.
func (rq *request) netblockRequests(netblock netip.Prefix) int64 {
return rq.h.limiter.Requests(netblock) + 1
}
// netblock is the netblock a ban on the client covers: its IPv4 address,
// widened to SWWAF_BAN_SCOPE_V4_PREFIX, or the IPv6 group clientGroup
// counts it in.
func (rq *request) netblock() netip.Prefix {
addr := rq.client.Unmap()
if addr.Is4() {
return netip.PrefixFrom(addr, rq.h.config.BanScopeV4Prefix).Masked()
}
return clientGroup(addr)
}
// banExpires is when ban ends, as the log line gives it: a time, or
// permanent.
func banExpires(ban bans.Ban) string {
if ban.Permanent() {
return "permanent"
}
return requestlog.FormatTime(ban.Expires)
}