mirror of https://github.com/go-gitea/gitea.git
activitypub: implement the ReqSignature middleware
Signed-off-by: Loïc Dachary <loic@dachary.org>pull/19981/head
Loïc Dachary
3 years ago
committed by
Anthony Wang
parent
15c1f6218c
commit
97fedf2616
@ -0,0 +1,158 @@
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// Copyright 2021 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package activitypub
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import (
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"context"
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"crypto"
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"crypto/x509"
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"encoding/pem"
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"fmt"
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"io"
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"net/http"
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"net/url"
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"code.gitea.io/gitea/modules/activitypub"
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gitea_context "code.gitea.io/gitea/modules/context"
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"code.gitea.io/gitea/modules/json"
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"code.gitea.io/gitea/modules/setting"
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"github.com/go-fed/activity/pub"
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"github.com/go-fed/activity/streams"
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"github.com/go-fed/activity/streams/vocab"
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"github.com/go-fed/httpsig"
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)
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type publicKeyer interface {
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GetW3IDSecurityV1PublicKey() vocab.W3IDSecurityV1PublicKeyProperty
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}
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func getPublicKeyFromResponse(ctx context.Context, b []byte, keyID *url.URL) (p crypto.PublicKey, err error) {
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m := make(map[string]interface{})
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err = json.Unmarshal(b, &m)
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if err != nil {
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return
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}
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var t vocab.Type
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t, err = streams.ToType(ctx, m)
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if err != nil {
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return
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}
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pker, ok := t.(publicKeyer)
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if !ok {
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err = fmt.Errorf("ActivityStreams type cannot be converted to one known to have publicKey property: %T", t)
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return
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}
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pkp := pker.GetW3IDSecurityV1PublicKey()
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if pkp == nil {
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err = fmt.Errorf("publicKey property is not provided")
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return
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}
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var pkpFound vocab.W3IDSecurityV1PublicKey
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for pkpIter := pkp.Begin(); pkpIter != pkp.End(); pkpIter = pkpIter.Next() {
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if !pkpIter.IsW3IDSecurityV1PublicKey() {
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continue
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}
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pkValue := pkpIter.Get()
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var pkID *url.URL
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pkID, err = pub.GetId(pkValue)
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if err != nil {
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return
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}
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if pkID.String() != keyID.String() {
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continue
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}
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pkpFound = pkValue
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break
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}
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if pkpFound == nil {
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err = fmt.Errorf("cannot find publicKey with id: %s in %s", keyID, b)
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return
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}
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pkPemProp := pkpFound.GetW3IDSecurityV1PublicKeyPem()
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if pkPemProp == nil || !pkPemProp.IsXMLSchemaString() {
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err = fmt.Errorf("publicKeyPem property is not provided or it is not embedded as a value")
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return
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}
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pubKeyPem := pkPemProp.Get()
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var block *pem.Block
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block, _ = pem.Decode([]byte(pubKeyPem))
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if block == nil || block.Type != "PUBLIC KEY" {
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err = fmt.Errorf("could not decode publicKeyPem to PUBLIC KEY pem block type")
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return
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}
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p, err = x509.ParsePKIXPublicKey(block.Bytes)
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return
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}
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func fetch(iri *url.URL) (b []byte, err error) {
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var req *http.Request
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req, err = http.NewRequest(http.MethodGet, iri.String(), nil)
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if err != nil {
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return
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}
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req.Header.Add("Accept", activitypub.ActivityStreamsContentType)
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req.Header.Add("Accept-Charset", "utf-8")
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clock, err := activitypub.NewClock()
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if err != nil {
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return
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}
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req.Header.Add("Date", fmt.Sprintf("%s GMT", clock.Now().UTC().Format("Mon, 02 Jan 2006 15:04:05")))
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var resp *http.Response
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client := &http.Client{}
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resp, err = client.Do(req)
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if err != nil {
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return
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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err = fmt.Errorf("url IRI fetch [%s] failed with status (%d): %s", iri, resp.StatusCode, resp.Status)
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return
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}
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b, err = io.ReadAll(resp.Body)
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return
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}
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func verifyHTTPSignatures(ctx *gitea_context.APIContext) (authenticated bool, err error) {
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r := ctx.Req
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// 1. Figure out what key we need to verify
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var v httpsig.Verifier
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v, err = httpsig.NewVerifier(r)
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if err != nil {
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return
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}
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ID := v.KeyId()
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var idIRI *url.URL
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idIRI, err = url.Parse(ID)
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if err != nil {
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return
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}
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// 2. Fetch the public key of the other actor
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var b []byte
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b, err = fetch(idIRI)
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if err != nil {
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return
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}
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pKey, err := getPublicKeyFromResponse(*ctx, b, idIRI)
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if err != nil {
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return
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}
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// 3. Verify the other actor's key
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algo := httpsig.Algorithm(setting.Federation.Algorithms[0])
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authenticated = nil == v.Verify(pKey, algo)
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return
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}
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// ReqSignature function
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func ReqSignature() func(ctx *gitea_context.APIContext) {
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return func(ctx *gitea_context.APIContext) {
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if authenticated, err := verifyHTTPSignatures(ctx); err != nil {
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ctx.Error(http.StatusInternalServerError, "verifyHttpSignatures", err)
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} else if !authenticated {
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ctx.Error(http.StatusForbidden, "reqSignature", "request signature verification failed")
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}
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}
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}
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