certificates/authority/linkedca.go
2022-03-21 19:24:05 -07:00

503 lines
14 KiB
Go

package authority
import (
"context"
"crypto"
"crypto/sha256"
"crypto/tls"
"crypto/x509"
"encoding/hex"
"encoding/pem"
"fmt"
"net/url"
"regexp"
"strings"
"time"
"github.com/pkg/errors"
"github.com/smallstep/certificates/authority/provisioner"
"github.com/smallstep/certificates/db"
"go.step.sm/crypto/jose"
"go.step.sm/crypto/keyutil"
"go.step.sm/crypto/tlsutil"
"go.step.sm/crypto/x509util"
"go.step.sm/linkedca"
"golang.org/x/crypto/ssh"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"
)
const uuidPattern = "^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}$"
type linkedCaClient struct {
renewer *tlsutil.Renewer
client linkedca.MajordomoClient
authorityID string
}
type linkedCAClaims struct {
jose.Claims
SANs []string `json:"sans"`
SHA string `json:"sha"`
}
func newLinkedCAClient(token string) (*linkedCaClient, error) {
tok, err := jose.ParseSigned(token)
if err != nil {
return nil, errors.Wrap(err, "error parsing token")
}
var claims linkedCAClaims
if err := tok.UnsafeClaimsWithoutVerification(&claims); err != nil {
return nil, errors.Wrap(err, "error parsing token")
}
// Validate claims
if len(claims.Audience) != 1 {
return nil, errors.New("error parsing token: invalid aud claim")
}
if claims.SHA == "" {
return nil, errors.New("error parsing token: invalid sha claim")
}
// Get linkedCA endpoint from audience.
u, err := url.Parse(claims.Audience[0])
if err != nil {
return nil, errors.New("error parsing token: invalid aud claim")
}
// Get authority from SANs
authority, err := getAuthority(claims.SANs)
if err != nil {
return nil, err
}
// Create csr to login with
signer, err := keyutil.GenerateDefaultSigner()
if err != nil {
return nil, err
}
csr, err := x509util.CreateCertificateRequest(claims.Subject, claims.SANs, signer)
if err != nil {
return nil, err
}
// Get and verify root certificate
root, err := getRootCertificate(u.Host, claims.SHA)
if err != nil {
return nil, err
}
pool := x509.NewCertPool()
pool.AddCert(root)
// Login with majordomo and get certificates
cert, tlsConfig, err := login(authority, token, csr, signer, u.Host, pool)
if err != nil {
return nil, err
}
// Start TLS renewer and set the GetClientCertificate callback to it.
renewer, err := tlsutil.NewRenewer(cert, tlsConfig, func() (*tls.Certificate, *tls.Config, error) {
return login(authority, token, csr, signer, u.Host, pool)
})
if err != nil {
return nil, err
}
tlsConfig.GetClientCertificate = renewer.GetClientCertificate
// Start mTLS client
conn, err := grpc.Dial(u.Host, grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)))
if err != nil {
return nil, errors.Wrapf(err, "error connecting %s", u.Host)
}
return &linkedCaClient{
renewer: renewer,
client: linkedca.NewMajordomoClient(conn),
authorityID: authority,
}, nil
}
func (c *linkedCaClient) Run() {
c.renewer.Run()
}
func (c *linkedCaClient) Stop() {
c.renewer.Stop()
}
func (c *linkedCaClient) CreateProvisioner(ctx context.Context, prov *linkedca.Provisioner) error {
resp, err := c.client.CreateProvisioner(ctx, &linkedca.CreateProvisionerRequest{
Type: prov.Type,
Name: prov.Name,
Details: prov.Details,
Claims: prov.Claims,
X509Template: prov.X509Template,
SshTemplate: prov.SshTemplate,
})
if err != nil {
return errors.Wrap(err, "error creating provisioner")
}
prov.Id = resp.Id
prov.AuthorityId = resp.AuthorityId
return nil
}
func (c *linkedCaClient) GetProvisioner(ctx context.Context, id string) (*linkedca.Provisioner, error) {
resp, err := c.client.GetProvisioner(ctx, &linkedca.GetProvisionerRequest{
Id: id,
})
if err != nil {
return nil, errors.Wrap(err, "error getting provisioners")
}
return resp, nil
}
func (c *linkedCaClient) GetProvisioners(ctx context.Context) ([]*linkedca.Provisioner, error) {
resp, err := c.client.GetConfiguration(ctx, &linkedca.ConfigurationRequest{
AuthorityId: c.authorityID,
})
if err != nil {
return nil, errors.Wrap(err, "error getting provisioners")
}
return resp.Provisioners, nil
}
func (c *linkedCaClient) UpdateProvisioner(ctx context.Context, prov *linkedca.Provisioner) error {
_, err := c.client.UpdateProvisioner(ctx, &linkedca.UpdateProvisionerRequest{
Id: prov.Id,
Name: prov.Name,
Details: prov.Details,
Claims: prov.Claims,
X509Template: prov.X509Template,
SshTemplate: prov.SshTemplate,
})
return errors.Wrap(err, "error updating provisioner")
}
func (c *linkedCaClient) DeleteProvisioner(ctx context.Context, id string) error {
_, err := c.client.DeleteProvisioner(ctx, &linkedca.DeleteProvisionerRequest{
Id: id,
})
return errors.Wrap(err, "error deleting provisioner")
}
func (c *linkedCaClient) CreateAdmin(ctx context.Context, adm *linkedca.Admin) error {
resp, err := c.client.CreateAdmin(ctx, &linkedca.CreateAdminRequest{
Subject: adm.Subject,
ProvisionerId: adm.ProvisionerId,
Type: adm.Type,
})
if err != nil {
return errors.Wrap(err, "error creating admin")
}
adm.Id = resp.Id
adm.AuthorityId = resp.AuthorityId
return nil
}
func (c *linkedCaClient) GetAdmin(ctx context.Context, id string) (*linkedca.Admin, error) {
resp, err := c.client.GetAdmin(ctx, &linkedca.GetAdminRequest{
Id: id,
})
if err != nil {
return nil, errors.Wrap(err, "error getting admins")
}
return resp, nil
}
func (c *linkedCaClient) GetAdmins(ctx context.Context) ([]*linkedca.Admin, error) {
resp, err := c.client.GetConfiguration(ctx, &linkedca.ConfigurationRequest{
AuthorityId: c.authorityID,
})
if err != nil {
return nil, errors.Wrap(err, "error getting admins")
}
return resp.Admins, nil
}
func (c *linkedCaClient) UpdateAdmin(ctx context.Context, adm *linkedca.Admin) error {
_, err := c.client.UpdateAdmin(ctx, &linkedca.UpdateAdminRequest{
Id: adm.Id,
Type: adm.Type,
})
return errors.Wrap(err, "error updating admin")
}
func (c *linkedCaClient) DeleteAdmin(ctx context.Context, id string) error {
_, err := c.client.DeleteAdmin(ctx, &linkedca.DeleteAdminRequest{
Id: id,
})
return errors.Wrap(err, "error deleting admin")
}
func (c *linkedCaClient) StoreCertificateChain(prov provisioner.Interface, fullchain ...*x509.Certificate) error {
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
_, err := c.client.PostCertificate(ctx, &linkedca.CertificateRequest{
PemCertificate: serializeCertificateChain(fullchain[0]),
PemCertificateChain: serializeCertificateChain(fullchain[1:]...),
Provisioner: createProvisionerIdentity(prov),
})
return errors.Wrap(err, "error posting certificate")
}
func (c *linkedCaClient) StoreRenewedCertificate(parent *x509.Certificate, fullchain ...*x509.Certificate) error {
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
_, err := c.client.PostCertificate(ctx, &linkedca.CertificateRequest{
PemCertificate: serializeCertificateChain(fullchain[0]),
PemCertificateChain: serializeCertificateChain(fullchain[1:]...),
PemParentCertificate: serializeCertificateChain(parent),
})
return errors.Wrap(err, "error posting certificate")
}
func (c *linkedCaClient) StoreSSHCertificate(crt *ssh.Certificate) error {
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
_, err := c.client.PostSSHCertificate(ctx, &linkedca.SSHCertificateRequest{
Certificate: string(ssh.MarshalAuthorizedKey(crt)),
})
return errors.Wrap(err, "error posting ssh certificate")
}
func (c *linkedCaClient) Revoke(crt *x509.Certificate, rci *db.RevokedCertificateInfo) error {
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
_, err := c.client.RevokeCertificate(ctx, &linkedca.RevokeCertificateRequest{
Serial: rci.Serial,
PemCertificate: serializeCertificate(crt),
Reason: rci.Reason,
ReasonCode: linkedca.RevocationReasonCode(rci.ReasonCode),
Passive: true,
})
return errors.Wrap(err, "error revoking certificate")
}
func (c *linkedCaClient) RevokeSSH(cert *ssh.Certificate, rci *db.RevokedCertificateInfo) error {
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
_, err := c.client.RevokeSSHCertificate(ctx, &linkedca.RevokeSSHCertificateRequest{
Serial: rci.Serial,
Certificate: serializeSSHCertificate(cert),
Reason: rci.Reason,
ReasonCode: linkedca.RevocationReasonCode(rci.ReasonCode),
Passive: true,
})
return errors.Wrap(err, "error revoking ssh certificate")
}
func (c *linkedCaClient) IsRevoked(serial string) (bool, error) {
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
resp, err := c.client.GetCertificateStatus(ctx, &linkedca.GetCertificateStatusRequest{
Serial: serial,
})
if err != nil {
return false, errors.Wrap(err, "error getting certificate status")
}
return resp.Status != linkedca.RevocationStatus_ACTIVE, nil
}
func (c *linkedCaClient) IsSSHRevoked(serial string) (bool, error) {
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
resp, err := c.client.GetSSHCertificateStatus(ctx, &linkedca.GetSSHCertificateStatusRequest{
Serial: serial,
})
if err != nil {
return false, errors.Wrap(err, "error getting certificate status")
}
return resp.Status != linkedca.RevocationStatus_ACTIVE, nil
}
func createProvisionerIdentity(prov provisioner.Interface) *linkedca.ProvisionerIdentity {
if prov == nil {
return nil
}
return &linkedca.ProvisionerIdentity{
Id: prov.GetID(),
Type: linkedca.Provisioner_Type(prov.GetType()),
Name: prov.GetName(),
}
}
func serializeCertificate(crt *x509.Certificate) string {
if crt == nil {
return ""
}
return string(pem.EncodeToMemory(&pem.Block{
Type: "CERTIFICATE",
Bytes: crt.Raw,
}))
}
func serializeCertificateChain(fullchain ...*x509.Certificate) string {
var chain string
for _, crt := range fullchain {
chain += string(pem.EncodeToMemory(&pem.Block{
Type: "CERTIFICATE",
Bytes: crt.Raw,
}))
}
return chain
}
func serializeSSHCertificate(crt *ssh.Certificate) string {
if crt == nil {
return ""
}
return string(ssh.MarshalAuthorizedKey(crt))
}
func getAuthority(sans []string) (string, error) {
for _, s := range sans {
if strings.HasPrefix(s, "urn:smallstep:authority:") {
if regexp.MustCompile(uuidPattern).MatchString(s[24:]) {
return s[24:], nil
}
}
}
return "", fmt.Errorf("error parsing token: invalid sans claim")
}
// getRootCertificate creates an insecure majordomo client and returns the
// verified root certificate.
func getRootCertificate(endpoint, fingerprint string) (*x509.Certificate, error) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
conn, err := grpc.DialContext(ctx, endpoint, grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{
InsecureSkipVerify: true,
})))
if err != nil {
return nil, errors.Wrapf(err, "error connecting %s", endpoint)
}
ctx, cancel = context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
client := linkedca.NewMajordomoClient(conn)
resp, err := client.GetRootCertificate(ctx, &linkedca.GetRootCertificateRequest{
Fingerprint: fingerprint,
})
if err != nil {
return nil, fmt.Errorf("error getting root certificate: %w", err)
}
var block *pem.Block
b := []byte(resp.PemCertificate)
for len(b) > 0 {
block, b = pem.Decode(b)
if block == nil {
break
}
if block.Type != "CERTIFICATE" || len(block.Headers) != 0 {
continue
}
cert, err := x509.ParseCertificate(block.Bytes)
if err != nil {
return nil, fmt.Errorf("error parsing certificate: %w", err)
}
// verify the sha256
sum := sha256.Sum256(cert.Raw)
if !strings.EqualFold(fingerprint, hex.EncodeToString(sum[:])) {
return nil, fmt.Errorf("error verifying certificate: SHA256 fingerprint does not match")
}
return cert, nil
}
return nil, fmt.Errorf("error getting root certificate: certificate not found")
}
// login creates a new majordomo client with just the root ca pool and returns
// the signed certificate and tls configuration.
func login(authority, token string, csr *x509.CertificateRequest, signer crypto.PrivateKey, endpoint string, rootCAs *x509.CertPool) (*tls.Certificate, *tls.Config, error) {
// Connect to majordomo
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
conn, err := grpc.DialContext(ctx, endpoint, grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{
RootCAs: rootCAs,
})))
if err != nil {
return nil, nil, errors.Wrapf(err, "error connecting %s", endpoint)
}
// Login to get the signed certificate
ctx, cancel = context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
client := linkedca.NewMajordomoClient(conn)
resp, err := client.Login(ctx, &linkedca.LoginRequest{
AuthorityId: authority,
Token: token,
PemCertificateRequest: string(pem.EncodeToMemory(&pem.Block{
Type: "CERTIFICATE REQUEST",
Bytes: csr.Raw,
})),
})
if err != nil {
return nil, nil, errors.Wrapf(err, "error logging in %s", endpoint)
}
// Parse login response
var block *pem.Block
var bundle []*x509.Certificate
rest := []byte(resp.PemCertificateChain)
for {
block, rest = pem.Decode(rest)
if block == nil {
break
}
if block.Type != "CERTIFICATE" {
return nil, nil, errors.New("error decoding login response: pemCertificateChain is not a certificate bundle")
}
crt, err := x509.ParseCertificate(block.Bytes)
if err != nil {
return nil, nil, errors.Wrap(err, "error parsing login response")
}
bundle = append(bundle, crt)
}
if len(bundle) == 0 {
return nil, nil, errors.New("error decoding login response: pemCertificateChain should not be empty")
}
// Build tls.Certificate with PemCertificate and intermediates in the
// PemCertificateChain
cert := &tls.Certificate{
PrivateKey: signer,
}
rest = []byte(resp.PemCertificate)
for {
block, rest = pem.Decode(rest)
if block == nil {
break
}
if block.Type == "CERTIFICATE" {
leaf, err := x509.ParseCertificate(block.Bytes)
if err != nil {
return nil, nil, errors.Wrap(err, "error parsing pemCertificate")
}
cert.Certificate = append(cert.Certificate, block.Bytes)
cert.Leaf = leaf
}
}
// Add intermediates to the tls.Certificate
last := len(bundle) - 1
for i := 0; i < last; i++ {
cert.Certificate = append(cert.Certificate, bundle[i].Raw)
}
// Add root to the pool if it's not there yet
rootCAs.AddCert(bundle[last])
return cert, &tls.Config{
RootCAs: rootCAs,
}, nil
}