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Diffstat (limited to 'routers/api/v1/activitypub/reqsignature.go')
-rw-r--r--routers/api/v1/activitypub/reqsignature.go99
1 files changed, 99 insertions, 0 deletions
diff --git a/routers/api/v1/activitypub/reqsignature.go b/routers/api/v1/activitypub/reqsignature.go
new file mode 100644
index 0000000..6003f66
--- /dev/null
+++ b/routers/api/v1/activitypub/reqsignature.go
@@ -0,0 +1,99 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package activitypub
+
+import (
+ "crypto"
+ "crypto/x509"
+ "encoding/pem"
+ "fmt"
+ "io"
+ "net/http"
+ "net/url"
+
+ "code.gitea.io/gitea/modules/activitypub"
+ "code.gitea.io/gitea/modules/httplib"
+ "code.gitea.io/gitea/modules/log"
+ "code.gitea.io/gitea/modules/setting"
+ gitea_context "code.gitea.io/gitea/services/context"
+
+ ap "github.com/go-ap/activitypub"
+ "github.com/go-fed/httpsig"
+)
+
+func getPublicKeyFromResponse(b []byte, keyID *url.URL) (p crypto.PublicKey, err error) {
+ person := ap.PersonNew(ap.IRI(keyID.String()))
+ err = person.UnmarshalJSON(b)
+ if err != nil {
+ return nil, fmt.Errorf("ActivityStreams type cannot be converted to one known to have publicKey property: %w", err)
+ }
+ pubKey := person.PublicKey
+ if pubKey.ID.String() != keyID.String() {
+ return nil, fmt.Errorf("cannot find publicKey with id: %s in %s", keyID, string(b))
+ }
+ pubKeyPem := pubKey.PublicKeyPem
+ block, _ := pem.Decode([]byte(pubKeyPem))
+ if block == nil || block.Type != "PUBLIC KEY" {
+ return nil, fmt.Errorf("could not decode publicKeyPem to PUBLIC KEY pem block type")
+ }
+ p, err = x509.ParsePKIXPublicKey(block.Bytes)
+ return p, err
+}
+
+func fetch(iri *url.URL) (b []byte, err error) {
+ req := httplib.NewRequest(iri.String(), http.MethodGet)
+ req.Header("Accept", activitypub.ActivityStreamsContentType)
+ req.Header("User-Agent", "Gitea/"+setting.AppVer)
+ resp, err := req.Response()
+ if err != nil {
+ return nil, err
+ }
+ defer resp.Body.Close()
+
+ if resp.StatusCode != http.StatusOK {
+ return nil, fmt.Errorf("url IRI fetch [%s] failed with status (%d): %s", iri, resp.StatusCode, resp.Status)
+ }
+ b, err = io.ReadAll(io.LimitReader(resp.Body, setting.Federation.MaxSize))
+ return b, err
+}
+
+func verifyHTTPSignatures(ctx *gitea_context.APIContext) (authenticated bool, err error) {
+ r := ctx.Req
+
+ // 1. Figure out what key we need to verify
+ v, err := httpsig.NewVerifier(r)
+ if err != nil {
+ return false, err
+ }
+ ID := v.KeyId()
+ idIRI, err := url.Parse(ID)
+ if err != nil {
+ return false, err
+ }
+ // 2. Fetch the public key of the other actor
+ b, err := fetch(idIRI)
+ if err != nil {
+ return false, err
+ }
+ pubKey, err := getPublicKeyFromResponse(b, idIRI)
+ if err != nil {
+ return false, err
+ }
+ // 3. Verify the other actor's key
+ algo := httpsig.Algorithm(setting.Federation.Algorithms[0])
+ authenticated = v.Verify(pubKey, algo) == nil
+ return authenticated, err
+}
+
+// ReqHTTPSignature function
+func ReqHTTPSignature() func(ctx *gitea_context.APIContext) {
+ return func(ctx *gitea_context.APIContext) {
+ if authenticated, err := verifyHTTPSignatures(ctx); err != nil {
+ log.Warn("verifyHttpSignatures failed: %v", err)
+ ctx.Error(http.StatusBadRequest, "reqSignature", "request signature verification failed")
+ } else if !authenticated {
+ ctx.Error(http.StatusForbidden, "reqSignature", "request signature verification failed")
+ }
+ }
+}