Add option to provide signature for a token to verify key ownership (#14054)

* Add option to provide signed token to verify key ownership

Currently we will only allow a key to be matched to a user if it matches
an activated email address. This PR provides a different mechanism - if
the user provides a signature for automatically generated token (based
on the timestamp, user creation time, user ID, username and primary
email.

* Ensure verified keys can act for all active emails for the user

* Add code to mark keys as verified

* Slight UI adjustments

* Slight UI adjustments 2

* Simplify signature verification slightly

* fix postgres test

* add api routes

* handle swapped primary-keys

* Verify the no-reply address for verified keys

* Only add email addresses that are activated to keys

* Fix committer shortcut properly

* Restructure gpg_keys.go

* Use common Verification Token code

Signed-off-by: Andrew Thornton <art27@cantab.net>

models/gpg_key_add.go

@@ -0,0 +1,125 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package models
+
+import (
+	"strings"
+
+	"code.gitea.io/gitea/modules/log"
+
+	"github.com/keybase/go-crypto/openpgp"
+)
+
+//   __________________  ________   ____  __.
+//  /  _____/\______   \/  _____/  |    |/ _|____ ___.__.
+// /   \  ___ |     ___/   \  ___  |      <_/ __ <   |  |
+// \    \_\  \|    |   \    \_\  \ |    |  \  ___/\___  |
+//  \______  /|____|    \______  / |____|__ \___  > ____|
+//         \/                  \/          \/   \/\/
+//    _____       .___  .___
+//   /  _  \    __| _/__| _/
+//	/  /_\  \  / __ |/ __ |
+// /    |    \/ /_/ / /_/ |
+// \____|__  /\____ \____ |
+//         \/      \/    \/
+
+// This file contains functions relating to adding GPG Keys
+
+// addGPGKey add key, import and subkeys to database
+func addGPGKey(e Engine, key *GPGKey, content string) (err error) {
+	// Add GPGKeyImport
+	if _, err = e.Insert(GPGKeyImport{
+		KeyID:   key.KeyID,
+		Content: content,
+	}); err != nil {
+		return err
+	}
+	// Save GPG primary key.
+	if _, err = e.Insert(key); err != nil {
+		return err
+	}
+	// Save GPG subs key.
+	for _, subkey := range key.SubsKey {
+		if err := addGPGSubKey(e, subkey); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// addGPGSubKey add subkeys to database
+func addGPGSubKey(e Engine, key *GPGKey) (err error) {
+	// Save GPG primary key.
+	if _, err = e.Insert(key); err != nil {
+		return err
+	}
+	// Save GPG subs key.
+	for _, subkey := range key.SubsKey {
+		if err := addGPGSubKey(e, subkey); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// AddGPGKey adds new public key to database.
+func AddGPGKey(ownerID int64, content, token, signature string) ([]*GPGKey, error) {
+	ekeys, err := checkArmoredGPGKeyString(content)
+	if err != nil {
+		return nil, err
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+	if err = sess.Begin(); err != nil {
+		return nil, err
+	}
+	keys := make([]*GPGKey, 0, len(ekeys))
+
+	verified := false
+	// Handle provided signature
+	if signature != "" {
+		signer, err := openpgp.CheckArmoredDetachedSignature(ekeys, strings.NewReader(token), strings.NewReader(signature))
+		if err != nil {
+			signer, err = openpgp.CheckArmoredDetachedSignature(ekeys, strings.NewReader(token+"\n"), strings.NewReader(signature))
+		}
+		if err != nil {
+			signer, err = openpgp.CheckArmoredDetachedSignature(ekeys, strings.NewReader(token+"\r\n"), strings.NewReader(signature))
+		}
+		if err != nil {
+			log.Error("Unable to validate token signature. Error: %v", err)
+			return nil, ErrGPGInvalidTokenSignature{
+				ID:      ekeys[0].PrimaryKey.KeyIdString(),
+				Wrapped: err,
+			}
+		}
+		ekeys = []*openpgp.Entity{signer}
+		verified = true
+	}
+
+	for _, ekey := range ekeys {
+		// Key ID cannot be duplicated.
+		has, err := sess.Where("key_id=?", ekey.PrimaryKey.KeyIdString()).
+			Get(new(GPGKey))
+		if err != nil {
+			return nil, err
+		} else if has {
+			return nil, ErrGPGKeyIDAlreadyUsed{ekey.PrimaryKey.KeyIdString()}
+		}
+
+		// Get DB session
+
+		key, err := parseGPGKey(ownerID, ekey, verified)
+		if err != nil {
+			return nil, err
+		}
+
+		if err = addGPGKey(sess, key, content); err != nil {
+			return nil, err
+		}
+		keys = append(keys, key)
+	}
+	return keys, sess.Commit()
+}