Allow configuring old verify keys (#1443)

* Allow configuring old verify keys

* Update sample config

* Update sample config

* Fix config population

* Key ID formatting validity of old_verify_keys

* Update comment
This commit is contained in:
Neil Alexander 2020-09-25 10:58:53 +01:00 committed by GitHub
parent 6fbf89a166
commit 145db37d89
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 62 additions and 6 deletions

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@ -38,6 +38,14 @@ global:
# The path to the signing private key file, used to sign requests and events.
private_key: matrix_key.pem
# The paths and expiry timestamps (as a UNIX timestamp in millisecond precision)
# to old signing private keys that were formerly in use on this domain. These
# keys will not be used for federation request or event signing, but will be
# provided to any other homeserver that asks when trying to verify old events.
# old_private_keys:
# - private_key: old_matrix_key.pem
# expired_at: 1601024554498
# How long a remote server can cache our server signing key before requesting it
# again. Increasing this number will reduce the number of requests made by other
# servers for our key but increases the period that a compromised key will be

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@ -136,6 +136,8 @@ func localKeys(cfg *config.FederationAPI, validUntil time.Time) (*gomatrixserver
var keys gomatrixserverlib.ServerKeys
keys.ServerName = cfg.Matrix.ServerName
keys.TLSFingerprints = cfg.TLSFingerPrints
keys.ValidUntilTS = gomatrixserverlib.AsTimestamp(validUntil)
publicKey := cfg.Matrix.PrivateKey.Public().(ed25519.PublicKey)
@ -145,9 +147,15 @@ func localKeys(cfg *config.FederationAPI, validUntil time.Time) (*gomatrixserver
},
}
keys.TLSFingerprints = cfg.TLSFingerPrints
keys.OldVerifyKeys = map[gomatrixserverlib.KeyID]gomatrixserverlib.OldVerifyKey{}
keys.ValidUntilTS = gomatrixserverlib.AsTimestamp(validUntil)
for _, oldVerifyKey := range cfg.Matrix.OldVerifyKeys {
keys.OldVerifyKeys[oldVerifyKey.KeyID] = gomatrixserverlib.OldVerifyKey{
VerifyKey: gomatrixserverlib.VerifyKey{
Key: gomatrixserverlib.Base64Bytes(oldVerifyKey.PrivateKey),
},
ExpiredTS: oldVerifyKey.ExpiredAt,
}
}
toSign, err := json.Marshal(keys.ServerKeyFields)
if err != nil {

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@ -228,10 +228,30 @@ func loadConfig(
return nil, err
}
if c.Global.KeyID, c.Global.PrivateKey, err = readKeyPEM(privateKeyPath, privateKeyData); err != nil {
if c.Global.KeyID, c.Global.PrivateKey, err = readKeyPEM(privateKeyPath, privateKeyData, true); err != nil {
return nil, err
}
for i, oldPrivateKey := range c.Global.OldVerifyKeys {
var oldPrivateKeyData []byte
oldPrivateKeyPath := absPath(basePath, oldPrivateKey.PrivateKeyPath)
oldPrivateKeyData, err = readFile(oldPrivateKeyPath)
if err != nil {
return nil, err
}
// NOTSPEC: Ordinarily we should enforce key ID formatting, but since there are
// a number of private keys out there with non-compatible symbols in them due
// to lack of validation in Synapse, we won't enforce that for old verify keys.
keyID, privateKey, perr := readKeyPEM(oldPrivateKeyPath, oldPrivateKeyData, false)
if perr != nil {
return nil, perr
}
c.Global.OldVerifyKeys[i].KeyID, c.Global.OldVerifyKeys[i].PrivateKey = keyID, privateKey
}
for _, certPath := range c.FederationAPI.FederationCertificatePaths {
absCertPath := absPath(basePath, certPath)
var pemData []byte
@ -444,7 +464,7 @@ func absPath(dir string, path Path) string {
return filepath.Join(dir, string(path))
}
func readKeyPEM(path string, data []byte) (gomatrixserverlib.KeyID, ed25519.PrivateKey, error) {
func readKeyPEM(path string, data []byte, enforceKeyIDFormat bool) (gomatrixserverlib.KeyID, ed25519.PrivateKey, error) {
for {
var keyBlock *pem.Block
keyBlock, data = pem.Decode(data)
@ -462,7 +482,7 @@ func readKeyPEM(path string, data []byte) (gomatrixserverlib.KeyID, ed25519.Priv
if !strings.HasPrefix(keyID, "ed25519:") {
return "", nil, fmt.Errorf("key ID %q doesn't start with \"ed25519:\" in %q", keyID, path)
}
if !keyIDRegexp.MatchString(keyID) {
if enforceKeyIDFormat && !keyIDRegexp.MatchString(keyID) {
return "", nil, fmt.Errorf("key ID %q in %q contains illegal characters (use a-z, A-Z, 0-9 and _ only)", keyID, path)
}
_, privKey, err := ed25519.GenerateKey(bytes.NewReader(keyBlock.Bytes))

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@ -22,6 +22,11 @@ type Global struct {
// prefix "ed25519:".
KeyID gomatrixserverlib.KeyID `yaml:"-"`
// Information about old private keys that used to be used to sign requests and
// events on this domain. They will not be used but will be advertised to other
// servers that ask for them to help verify old events.
OldVerifyKeys []OldVerifyKeys `yaml:"old_private_keys"`
// How long a remote server can cache our server key for before requesting it again.
// Increasing this number will reduce the number of requests made by remote servers
// for our key, but increases the period a compromised key will be considered valid
@ -60,6 +65,21 @@ func (c *Global) Verify(configErrs *ConfigErrors, isMonolith bool) {
c.Metrics.Verify(configErrs, isMonolith)
}
type OldVerifyKeys struct {
// Path to the private key.
PrivateKeyPath Path `yaml:"private_key"`
// The private key itself.
PrivateKey ed25519.PrivateKey `yaml:"-"`
// The key ID of the private key.
KeyID gomatrixserverlib.KeyID `yaml:"-"`
// When the private key was designed as "expired", as a UNIX timestamp
// in millisecond precision.
ExpiredAt gomatrixserverlib.Timestamp `yaml:"expired_at"`
}
// The configuration to use for Prometheus metrics
type Metrics struct {
// Whether or not the metrics are enabled

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@ -234,7 +234,7 @@ func (m mockReadFile) readFile(path string) ([]byte, error) {
}
func TestReadKey(t *testing.T) {
keyID, _, err := readKeyPEM("path/to/key", []byte(testKey))
keyID, _, err := readKeyPEM("path/to/key", []byte(testKey), true)
if err != nil {
t.Error("failed to load private key:", err)
}