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coraza.go
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coraza.go
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// Copyright 2023 The OWASP Coraza contributors
// SPDX-License-Identifier: Apache-2.0
package coraza
import (
"errors"
"net/http"
"path/filepath"
"strings"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
coreruleset "github.com/corazawaf/coraza-coreruleset/v4"
"github.com/corazawaf/coraza/v3"
"github.com/corazawaf/coraza/v3/types"
"github.com/jcchavezs/mergefs"
"github.com/jcchavezs/mergefs/io"
"go.uber.org/zap"
)
func init() {
caddy.RegisterModule(corazaModule{})
httpcaddyfile.RegisterHandlerDirective("coraza_waf", parseCaddyfile)
}
// corazaModule is a Web Application Firewall implementation for Caddy.
type corazaModule struct {
// deprecated
Include []string `json:"include"`
Directives string `json:"directives"`
LoadOWASPCRS bool `json:"load_owasp_crs"`
logger *zap.Logger
waf coraza.WAF
}
// CaddyModule returns the Caddy module information.
func (corazaModule) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.waf",
New: func() caddy.Module { return new(corazaModule) },
}
}
// Provision implements caddy.Provisioner.
func (m *corazaModule) Provision(ctx caddy.Context) error {
m.logger = ctx.Logger(m)
config := coraza.NewWAFConfig().
WithErrorCallback(newErrorCb(m.logger)).
WithDebugLogger(newLogger(m.logger))
if m.LoadOWASPCRS {
config = config.WithRootFS(mergefs.Merge(coreruleset.FS, io.OSFS))
}
if m.Directives != "" {
config = config.WithDirectives(m.Directives)
}
if len(m.Include) > 0 {
m.logger.Warn("'include' field is deprecated, please use the Include directive inside 'directives' field instead")
for _, file := range m.Include {
if strings.Contains(file, "*") {
m.logger.Debug("Preparing to expand glob", zap.String("pattern", file))
// we get files as expandables globs (with wildcard patterns)
fs, err := filepath.Glob(file)
if err != nil {
return err
}
m.logger.Debug("Glob expanded", zap.String("pattern", file), zap.Strings("files", fs))
for _, f := range fs {
config = config.WithDirectivesFromFile(f)
}
} else {
m.logger.Debug("File was not a pattern, compiling it", zap.String("file", file))
config = config.WithDirectivesFromFile(file)
}
}
}
var err error
m.waf, err = coraza.NewWAF(config)
return err
}
// Validate implements caddy.Validator.
func (m *corazaModule) Validate() error {
return nil
}
var errInterruptionTriggered = errors.New("interruption triggered")
// ServeHTTP implements caddyhttp.MiddlewareHandler.
func (m corazaModule) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
id := randomString(16)
tx := m.waf.NewTransactionWithID(id)
defer func() {
tx.ProcessLogging()
_ = tx.Close()
}()
// Early return, Coraza is not going to process any rule
if tx.IsRuleEngineOff() {
// response writer is not going to be wrapped, but used as-is
// to generate the response
return next.ServeHTTP(w, r)
}
repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
repl.Set("http.transaction_id", id)
// ProcessRequest is just a wrapper around ProcessConnection, ProcessURI,
// ProcessRequestHeaders and ProcessRequestBody.
// It fails if any of these functions returns an error and it stops on interruption.
if it, err := processRequest(tx, r); err != nil {
return caddyhttp.HandlerError{
StatusCode: http.StatusInternalServerError,
ID: tx.ID(),
Err: err,
}
} else if it != nil {
return caddyhttp.HandlerError{
StatusCode: obtainStatusCodeFromInterruptionOrDefault(it, http.StatusOK),
ID: tx.ID(),
Err: errInterruptionTriggered,
}
}
ww, processResponse := wrap(w, r, tx)
// We continue with the other middlewares by catching the response
if err := next.ServeHTTP(ww, r); err != nil {
return err
}
return processResponse(tx, r)
}
// Unmarshal Caddyfile implements caddyfile.Unmarshaler.
func (m *corazaModule) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
if !d.Next() {
return d.Err("expected token following filter")
}
m.Include = []string{}
for d.NextBlock(0) {
key := d.Val()
switch key {
case "load_owasp_crs":
if d.NextArg() {
return d.ArgErr()
}
m.LoadOWASPCRS = true
case "directives", "include":
var value string
if !d.Args(&value) {
// not enough args
return d.ArgErr()
}
if d.NextArg() {
// too many args
return d.ArgErr()
}
switch key {
case "include":
m.Include = append(m.Include, value)
case "directives":
m.Directives = value
}
default:
return d.Errf("invalid key %q", key)
}
}
return nil
}
// parseCaddyfile unmarshals tokens from h into a new Middleware.
func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
var m corazaModule
err := m.UnmarshalCaddyfile(h.Dispenser)
return m, err
}
func newErrorCb(logger *zap.Logger) func(types.MatchedRule) {
return func(mr types.MatchedRule) {
logMsg := mr.ErrorLog()
switch mr.Rule().Severity() {
case types.RuleSeverityEmergency,
types.RuleSeverityAlert,
types.RuleSeverityCritical,
types.RuleSeverityError:
logger.Error(logMsg)
case types.RuleSeverityWarning:
logger.Warn(logMsg)
case types.RuleSeverityNotice:
logger.Info(logMsg)
case types.RuleSeverityInfo:
logger.Info(logMsg)
case types.RuleSeverityDebug:
logger.Debug(logMsg)
}
}
}
// Interface guards
var (
_ caddy.Provisioner = (*corazaModule)(nil)
_ caddy.Validator = (*corazaModule)(nil)
_ caddyhttp.MiddlewareHandler = (*corazaModule)(nil)
_ caddyfile.Unmarshaler = (*corazaModule)(nil)
)