101 lines
2.6 KiB
Go
101 lines
2.6 KiB
Go
// Copyright 2022 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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"crypto"
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"crypto/x509"
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"encoding/pem"
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"fmt"
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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/setting"
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ap "github.com/go-ap/activitypub"
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"github.com/go-fed/httpsig"
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)
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func getPublicKeyFromResponse(b []byte, keyID *url.URL) (p crypto.PublicKey, err error) {
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person := ap.PersonNew(ap.IRI(keyID.String()))
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err = person.UnmarshalJSON(b)
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if err != nil {
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err = fmt.Errorf("ActivityStreams type cannot be converted to one known to have publicKey property: %v", err)
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return
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}
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pubKey := person.PublicKey
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if pubKey.ID.String() != keyID.String() {
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err = fmt.Errorf("cannot find publicKey with id: %s in %s", keyID, string(b))
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return
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}
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pubKeyPem := pubKey.PublicKeyPem
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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 p, err
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}
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func getKeyID(r *http.Request) (httpsig.Verifier, string, error) {
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v, err := httpsig.NewVerifier(r)
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if err != nil {
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return nil, "", err
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}
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return v, v.KeyId(), nil
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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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v, ID, err := getKeyID(r)
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if err != nil {
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return
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}
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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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b, err := activitypub.Fetch(idIRI)
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if err != nil {
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return
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}
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pubKey, err := getPublicKeyFromResponse(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 = v.Verify(pubKey, algo) == nil
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if !authenticated {
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return
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}
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// 4. Create a federated user for the actor
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var person ap.Person
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err = person.UnmarshalJSON(b)
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if err != nil {
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return
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}
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err = activitypub.FederatedUserNew(ctx, &person)
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return authenticated, err
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}
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// ReqHTTPSignature function
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func ReqHTTPSignature() 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.ServerError("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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