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// Copyright 2022 The Sigstore Authors
//
// 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 cache
import (
"context"
"crypto"
"crypto/x509"
"encoding/asn1"
"fmt"
"net/rpc"
"os"
"time"
"github.com/sigstore/gitsign/internal/cache/api"
"github.com/sigstore/gitsign/internal/config"
"github.com/sigstore/sigstore/pkg/cryptoutils"
)
type Client struct {
Client *rpc.Client
Roots *x509.CertPool
Intermediates *x509.CertPool
}
func (c *Client) GetCredentials(_ context.Context, cfg *config.Config) (crypto.PrivateKey, []byte, []byte, error) {
id, err := id()
if err != nil {
return nil, nil, nil, fmt.Errorf("error getting credential ID: %w", err)
}
resp := new(api.Credential)
if err := c.Client.Call("Service.GetCredential", api.GetCredentialRequest{
ID: id,
Config: cfg,
}, resp); err != nil {
return nil, nil, nil, err
}
privateKey, err := cryptoutils.UnmarshalPEMToPrivateKey(resp.PrivateKey, cryptoutils.SkipPassword)
if err != nil {
return nil, nil, nil, fmt.Errorf("error unmarshalling private key: %w", err)
}
// Check that the cert is in fact still valid.
certs, err := cryptoutils.UnmarshalCertificatesFromPEM(resp.Cert)
if err != nil {
return nil, nil, nil, fmt.Errorf("error unmarshalling cert: %w", err)
}
// There should really only be 1 cert, but check them all anyway.
for _, cert := range certs {
if len(cert.UnhandledCriticalExtensions) > 0 {
var unhandledExts []asn1.ObjectIdentifier
for _, oid := range cert.UnhandledCriticalExtensions {
if !oid.Equal(cryptoutils.SANOID) {
unhandledExts = append(unhandledExts, oid)
}
}
cert.UnhandledCriticalExtensions = unhandledExts
}
if _, err := cert.Verify(x509.VerifyOptions{
Roots: c.Roots,
Intermediates: c.Intermediates,
KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageCodeSigning},
// We're going to be using this key immediately, so we don't need a long window.
// Just make sure it's not about to expire.
CurrentTime: time.Now().Add(30 * time.Second),
}); err != nil {
return nil, nil, nil, fmt.Errorf("stored cert no longer valid: %w", err)
}
}
return privateKey, resp.Cert, resp.Chain, nil
}
func (c *Client) StoreCert(_ context.Context, priv crypto.PrivateKey, cert, chain []byte) error {
id, err := id()
if err != nil {
return fmt.Errorf("error getting credential ID: %w", err)
}
privPEM, err := cryptoutils.MarshalPrivateKeyToPEM(priv)
if err != nil {
return err
}
if err := c.Client.Call("Service.StoreCredential", api.StoreCredentialRequest{
ID: id,
Credential: &api.Credential{
PrivateKey: privPEM,
Cert: cert,
Chain: chain,
},
}, new(api.Credential)); err != nil {
return err
}
return err
}
func id() (string, error) {
// Prefix host name in case cache socket is being shared over a SSH session.
host, err := os.Hostname()
if err != nil {
return "", fmt.Errorf("error getting hostname: %w", err)
}
wd, err := os.Getwd()
if err != nil {
return "", fmt.Errorf("error getting working directory: %w", err)
}
return fmt.Sprintf("%s@%s", host, wd), nil
}
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