minio/cmd/certs.go
Andreas Auernhammer 21a3c0f482 disable elliptic curves P-384 and P-521 for TLS. (#5845)
This change disables the non-constant-time implementations of P-384 and P-521.
As a consequence a client using just these curves cannot connect to the server.
This should be no real issues because (all) clients at least support P-256.

Further this change also rejects ECDSA private keys of P-384 and P-521.
While non-constant-time implementations for the ECDHE exchange don't expose an
obvious vulnerability, using P-384 or P-521 keys for the ECDSA signature may allow
pratical timing attacks.

Fixes #5844
2018-04-24 15:47:30 -07:00

167 lines
4.9 KiB
Go

/*
* Minio Cloud Storage, (C) 2015, 2016, 2017 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"crypto"
"crypto/ecdsa"
"crypto/tls"
"crypto/x509"
"encoding/pem"
"fmt"
"io/ioutil"
"os"
)
// TLSPrivateKeyPassword is the environment variable which contains the password used
// to decrypt the TLS private key. It must be set if the TLS private key is
// password protected.
const TLSPrivateKeyPassword = "MINIO_CERT_PASSWD"
func parsePublicCertFile(certFile string) (x509Certs []*x509.Certificate, err error) {
// Read certificate file.
var data []byte
if data, err = ioutil.ReadFile(certFile); err != nil {
return nil, err
}
// Parse all certs in the chain.
current := data
for len(current) > 0 {
var pemBlock *pem.Block
if pemBlock, current = pem.Decode(current); pemBlock == nil {
return nil, fmt.Errorf("Could not read PEM block from file %s", certFile)
}
var x509Cert *x509.Certificate
if x509Cert, err = x509.ParseCertificate(pemBlock.Bytes); err != nil {
return nil, err
}
x509Certs = append(x509Certs, x509Cert)
}
if len(x509Certs) == 0 {
return nil, fmt.Errorf("Empty public certificate file %s", certFile)
}
return x509Certs, nil
}
func getRootCAs(certsCAsDir string) (*x509.CertPool, error) {
// Get all CA file names.
var caFiles []string
fis, err := readDir(certsCAsDir)
if err != nil {
return nil, err
}
for _, fi := range fis {
// Skip all directories.
if hasSuffix(fi, slashSeparator) {
continue
}
// We are only interested in regular files here.
caFiles = append(caFiles, pathJoin(certsCAsDir, fi))
}
if len(caFiles) == 0 {
return nil, nil
}
rootCAs, err := x509.SystemCertPool()
if err != nil {
// In some systems like Windows, system cert pool is not supported.
// Hence we create a new cert pool.
rootCAs = x509.NewCertPool()
}
// Load custom root CAs for client requests
for _, caFile := range caFiles {
caCert, err := ioutil.ReadFile(caFile)
if err != nil {
return nil, err
}
rootCAs.AppendCertsFromPEM(caCert)
}
return rootCAs, nil
}
// load an X509 key pair (private key , certificate) from the provided
// paths. The private key may be encrypted and is decrypted using the
// ENV_VAR: MINIO_CERT_PASSWD.
func loadX509KeyPair(certFile, keyFile string) (tls.Certificate, error) {
certPEMBlock, err := ioutil.ReadFile(certFile)
if err != nil {
return tls.Certificate{}, fmt.Errorf("TLS: failed to read cert file: %v", err)
}
keyPEMBlock, err := ioutil.ReadFile(keyFile)
if err != nil {
return tls.Certificate{}, fmt.Errorf("TLS: failed to read private key: %v", err)
}
key, rest := pem.Decode(keyPEMBlock)
if len(rest) > 0 {
return tls.Certificate{}, fmt.Errorf("TLS: private key contains additional data")
}
if x509.IsEncryptedPEMBlock(key) {
password, ok := os.LookupEnv(TLSPrivateKeyPassword)
if !ok {
return tls.Certificate{}, fmt.Errorf("TLS: private key is encrypted but no password is present - set env var: %s", TLSPrivateKeyPassword)
}
decryptedKey, decErr := x509.DecryptPEMBlock(key, []byte(password))
if decErr != nil {
return tls.Certificate{}, fmt.Errorf("TLS: failed to decrypt private key: %v", decErr)
}
keyPEMBlock = pem.EncodeToMemory(&pem.Block{Type: key.Type, Bytes: decryptedKey})
}
return tls.X509KeyPair(certPEMBlock, keyPEMBlock)
}
func getSSLConfig() (x509Certs []*x509.Certificate, rootCAs *x509.CertPool, tlsCert *tls.Certificate, secureConn bool, err error) {
if !(isFile(getPublicCertFile()) && isFile(getPrivateKeyFile())) {
return nil, nil, nil, false, nil
}
if x509Certs, err = parsePublicCertFile(getPublicCertFile()); err != nil {
return nil, nil, nil, false, err
}
var cert tls.Certificate
if cert, err = loadX509KeyPair(getPublicCertFile(), getPrivateKeyFile()); err != nil {
return nil, nil, nil, false, err
}
// Ensure that the private key is not a P-384 or P-521 EC key.
// The Go TLS stack does not provide constant-time implementations of P-384 and P-521.
if priv, ok := cert.PrivateKey.(crypto.Signer); ok {
if pub, ok := priv.Public().(*ecdsa.PublicKey); ok {
if name := pub.Params().Name; name == "P-384" || name == "P-521" { // unfortunately there is no cleaner way to check
return nil, nil, nil, false, fmt.Errorf("TLS: the ECDSA curve '%s' is not supported", name)
}
}
}
tlsCert = &cert
if rootCAs, err = getRootCAs(getCADir()); err != nil {
return nil, nil, nil, false, err
}
secureConn = true
return x509Certs, rootCAs, tlsCert, secureConn, nil
}