933c60bc3a
Currently when connections to vault fail, client perpetually retries this leads to assumptions that the server has issues and masks the problem. Re-purpose *crypto.Error* type to send appropriate errors back to the client.
372 lines
11 KiB
Go
372 lines
11 KiB
Go
// MinIO Cloud Storage, (C) 2019 MinIO, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package crypto
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import (
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"bytes"
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"crypto/tls"
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"crypto/x509"
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"encoding/json"
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"fmt"
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"io"
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"io/ioutil"
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"net/http"
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"net/url"
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"os"
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"path/filepath"
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"strings"
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)
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// KesConfig contains the configuration required
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// to initialize and connect to a kes server.
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type KesConfig struct {
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Enabled bool
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// The kes server endpoint.
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Endpoint string
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// The path to the TLS private key used
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// by MinIO to authenticate to the kes
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// server during the TLS handshake (mTLS).
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KeyFile string
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// The path to the TLS certificate used
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// by MinIO to authenticate to the kes
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// server during the TLS handshake (mTLS).
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//
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// The kes server will also allow or deny
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// access based on this certificate.
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// In particular, the kes server will
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// lookup the policy that corresponds to
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// the identity in this certificate.
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CertFile string
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// Path to a file or directory containing
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// the CA certificate(s) that issued / will
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// issue certificates for the kes server.
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//
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// This is required if the TLS certificate
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// of the kes server has not been issued
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// (e.g. b/c it's self-signed) by a CA that
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// MinIO trusts.
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CAPath string
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// The default key ID returned by KMS.KeyID().
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DefaultKeyID string
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// The HTTP transport configuration for
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// the KES client.
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Transport *http.Transport
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}
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// Verify verifies if the kes configuration is correct
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func (k KesConfig) Verify() (err error) {
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switch {
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case k.Endpoint == "":
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err = Errorf("crypto: missing kes endpoint")
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case k.CertFile == "":
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err = Errorf("crypto: missing cert file")
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case k.KeyFile == "":
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err = Errorf("crypto: missing key file")
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case k.DefaultKeyID == "":
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err = Errorf("crypto: missing default key id")
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}
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return err
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}
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type kesService struct {
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client *kesClient
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endpoint string
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defaultKeyID string
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}
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// NewKes returns a new kes KMS client. The returned KMS
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// uses the X.509 certificate to authenticate itself to
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// the kes server available at address.
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//
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// The defaultKeyID is the key ID returned when calling
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// KMS.KeyID().
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func NewKes(cfg KesConfig) (KMS, error) {
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cert, err := tls.LoadX509KeyPair(cfg.CertFile, cfg.KeyFile)
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if err != nil {
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return nil, err
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}
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certPool, err := loadCACertificates(cfg.CAPath)
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if err != nil {
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return nil, err
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}
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cfg.Transport.TLSClientConfig = &tls.Config{
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Certificates: []tls.Certificate{cert},
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RootCAs: certPool,
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}
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return &kesService{
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client: &kesClient{
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addr: cfg.Endpoint,
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httpClient: http.Client{
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Transport: cfg.Transport,
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},
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},
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endpoint: cfg.Endpoint,
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defaultKeyID: cfg.DefaultKeyID,
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}, nil
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}
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// KeyID returns the default key ID.
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func (kes *kesService) KeyID() string {
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return kes.defaultKeyID
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}
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// Info returns some status information about the KMS.
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func (kes *kesService) Info() KMSInfo {
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return KMSInfo{
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Endpoint: kes.endpoint,
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Name: kes.KeyID(),
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AuthType: "TLS",
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}
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}
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// GenerateKey returns a new plaintext key, generated by the KMS,
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// and a sealed version of this plaintext key encrypted using the
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// named key referenced by keyID. It also binds the generated key
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// cryptographically to the provided context.
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func (kes *kesService) GenerateKey(keyID string, ctx Context) (key [32]byte, sealedKey []byte, err error) {
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var context bytes.Buffer
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ctx.WriteTo(&context)
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var plainKey []byte
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plainKey, sealedKey, err = kes.client.GenerateDataKey(keyID, context.Bytes())
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if err != nil {
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return key, nil, err
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}
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if len(plainKey) != len(key) {
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return key, nil, Errorf("crypto: received invalid plaintext key size from KMS")
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}
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copy(key[:], plainKey)
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return key, sealedKey, nil
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}
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// UnsealKey returns the decrypted sealedKey as plaintext key.
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// Therefore it sends the sealedKey to the KMS which decrypts
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// it using the named key referenced by keyID and responses with
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// the plaintext key.
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//
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// The context must be same context as the one provided while
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// generating the plaintext key / sealedKey.
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func (kes *kesService) UnsealKey(keyID string, sealedKey []byte, ctx Context) (key [32]byte, err error) {
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var context bytes.Buffer
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ctx.WriteTo(&context)
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var plainKey []byte
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plainKey, err = kes.client.DecryptDataKey(keyID, sealedKey, context.Bytes())
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if err != nil {
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return key, err
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}
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if len(plainKey) != len(key) {
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return key, Errorf("crypto: received invalid plaintext key size from KMS")
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}
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copy(key[:], plainKey)
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return key, nil
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}
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// UpdateKey re-wraps the sealedKey if the master key referenced by the keyID
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// has been changed by the KMS operator - i.e. the master key has been rotated.
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// If the master key hasn't changed since the sealedKey has been created / updated
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// it may return the same sealedKey as rotatedKey.
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//
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// The context must be same context as the one provided while
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// generating the plaintext key / sealedKey.
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func (kes *kesService) UpdateKey(keyID string, sealedKey []byte, ctx Context) ([]byte, error) {
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_, err := kes.UnsealKey(keyID, sealedKey, ctx)
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if err != nil {
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return nil, err
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}
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// Currently a kes server does not support key rotation (of the same key)
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// Therefore, we simply return the same sealedKey.
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return sealedKey, nil
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}
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// kesClient implements the bare minimum functionality needed for
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// MinIO to talk to a KES server. In particular, it implements
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// GenerateDataKey (API: /v1/key/generate/) and
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// DecryptDataKey (API: /v1/key/decrypt/).
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type kesClient struct {
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addr string
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httpClient http.Client
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}
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// GenerateDataKey requests a new data key from the KES server.
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// On success, the KES server will respond with the plaintext key
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// and the ciphertext key as the plaintext key encrypted with
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// the key specified by name.
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//
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// The optional context is crytpo. bound to the generated data key
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// such that you have to provide the same context when decrypting
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// the data key.
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func (c *kesClient) GenerateDataKey(name string, context []byte) ([]byte, []byte, error) {
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type Request struct {
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Context []byte `json:"context"`
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}
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body, err := json.Marshal(Request{
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Context: context,
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})
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if err != nil {
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return nil, nil, err
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}
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url := fmt.Sprintf("%s/v1/key/generate/%s", c.addr, url.PathEscape(name))
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resp, err := c.httpClient.Post(url, "application/json", bytes.NewReader(body))
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if err != nil {
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return nil, nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, nil, c.parseErrorResponse(resp)
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}
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defer resp.Body.Close()
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type Response struct {
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Plaintext []byte `json:"plaintext"`
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Ciphertext []byte `json:"ciphertext"`
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}
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const limit = 1 << 20 // A plaintext/ciphertext key pair will never be larger than 1 MB
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var response Response
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if err = json.NewDecoder(io.LimitReader(resp.Body, limit)).Decode(&response); err != nil {
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return nil, nil, err
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}
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return response.Plaintext, response.Ciphertext, nil
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}
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// GenerateDataKey decrypts an encrypted data key with the key
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// specified by name by talking to the KES server.
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// On success, the KES server will respond with the plaintext key.
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//
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// The optional context must match the value you provided when
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// generating the data key.
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func (c *kesClient) DecryptDataKey(name string, ciphertext, context []byte) ([]byte, error) {
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type Request struct {
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Ciphertext []byte `json:"ciphertext"`
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Context []byte `json:"context"`
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}
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body, err := json.Marshal(Request{
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Ciphertext: ciphertext,
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Context: context,
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})
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if err != nil {
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return nil, err
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}
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url := fmt.Sprintf("%s/v1/key/decrypt/%s", c.addr, url.PathEscape(name))
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resp, err := c.httpClient.Post(url, "application/json", bytes.NewReader(body))
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, c.parseErrorResponse(resp)
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}
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defer resp.Body.Close()
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type Response struct {
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Plaintext []byte `json:"plaintext"`
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}
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const limit = 32 * 1024 // A data key will never be larger than 32 KB
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var response Response
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if err = json.NewDecoder(io.LimitReader(resp.Body, limit)).Decode(&response); err != nil {
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return nil, err
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}
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return response.Plaintext, nil
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}
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func (c *kesClient) parseErrorResponse(resp *http.Response) error {
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if resp.Body == nil {
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return nil
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}
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defer resp.Body.Close()
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const limit = 32 * 1024 // A (valid) error response will not be greater than 32 KB
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var errMsg strings.Builder
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if _, err := io.Copy(&errMsg, io.LimitReader(resp.Body, limit)); err != nil {
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return err
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}
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return Errorf("%s: %s", http.StatusText(resp.StatusCode), errMsg.String())
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}
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// loadCACertificates returns a new CertPool
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// that contains all system root CA certificates
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// and any PEM-encoded certificate(s) found at
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// path.
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//
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// If path is a file, loadCACertificates will
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// try to parse it as PEM-encoded certificate.
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// If this fails, it returns an error.
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//
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// If path is a directory it tries to parse each
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// file as PEM-encoded certificate and add it to
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// the CertPool. If a file is not a PEM certificate
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// it will be ignored.
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func loadCACertificates(path string) (*x509.CertPool, error) {
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rootCAs, _ := x509.SystemCertPool()
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if rootCAs == nil {
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// In some systems (like Windows) system cert pool is
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// not supported or no certificates are present on the
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// system - so we create a new cert pool.
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rootCAs = x509.NewCertPool()
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}
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if path == "" {
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return rootCAs, nil
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}
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stat, err := os.Stat(path)
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if err != nil {
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if os.IsNotExist(err) || os.IsPermission(err) {
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return rootCAs, nil
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}
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return nil, Errorf("crypto: cannot open '%s': %v", path, err)
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}
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// If path is a file, parse as PEM-encoded certifcate
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// and try to add it to the CertPool. If this fails
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// return an error.
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if !stat.IsDir() {
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cert, err := ioutil.ReadFile(path)
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if err != nil {
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return nil, err
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}
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if !rootCAs.AppendCertsFromPEM(cert) {
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return nil, Errorf("crypto: '%s' is not a valid PEM-encoded certificate", path)
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}
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return rootCAs, nil
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}
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// If path is a directory then try
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// to parse each file as PEM-encoded
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// certificate and add it to the CertPool.
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// If a file is not a PEM-encoded certificate
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// we ignore it.
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files, err := ioutil.ReadDir(path)
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if err != nil {
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return nil, err
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}
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for _, file := range files {
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cert, err := ioutil.ReadFile(filepath.Join(path, file.Name()))
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if err != nil {
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continue // ignore files which are not readable
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}
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rootCAs.AppendCertsFromPEM(cert) // ignore files which are not PEM certtificates
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}
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return rootCAs, nil
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}
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