package ca
import (
"bytes"
"context"
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
cryptorand "crypto/rand"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"encoding/asn1"
"encoding/pem"
"fmt"
"io"
"os"
"path/filepath"
"time"
cfcsr "github.com/cloudflare/cfssl/csr"
"github.com/cloudflare/cfssl/helpers"
"github.com/cloudflare/cfssl/initca"
cflog "github.com/cloudflare/cfssl/log"
cfsigner "github.com/cloudflare/cfssl/signer"
"github.com/cloudflare/cfssl/signer/local"
"github.com/docker/go-events"
"github.com/moby/swarmkit/v2/api"
"github.com/moby/swarmkit/v2/ca/pkcs8"
"github.com/moby/swarmkit/v2/connectionbroker"
"github.com/moby/swarmkit/v2/ioutils"
"github.com/opencontainers/go-digest"
"github.com/pkg/errors"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/status"
)
const (
// Security Strength Equivalence
//
// | ECC | DH/DSA/RSA |
// |----------|---------------|
// | 256 | 3072 |
// | 384 | 7680 |
// RootKeySize is the default size of the root CA key
// It would be ideal for the root key to use P-384, but in P-384 is not optimized in go yet :(
RootKeySize = 256
// RootKeyAlgo defines the default algorithm for the root CA Key
RootKeyAlgo = "ecdsa"
// RootCAExpiration represents the default expiration for the root CA in seconds (20 years)
RootCAExpiration = "630720000s"
// DefaultNodeCertExpiration represents the default expiration for node certificates (3 months)
DefaultNodeCertExpiration = 2160 * time.Hour
// CertBackdate represents the amount of time each certificate is backdated to try to avoid
// clock drift issues.
CertBackdate = 1 * time.Hour
// CertLowerRotationRange represents the minimum fraction of time that we will wait when randomly
// choosing our next certificate rotation
CertLowerRotationRange = 0.5
// CertUpperRotationRange represents the maximum fraction of time that we will wait when randomly
// choosing our next certificate rotation
CertUpperRotationRange = 0.8
// MinNodeCertExpiration represents the minimum expiration for node certificates
MinNodeCertExpiration = 1 * time.Hour
)
// BasicConstraintsOID is the ASN1 Object ID indicating a basic constraints extension
var BasicConstraintsOID = asn1.ObjectIdentifier{2, 5, 29, 19}
// A recoverableErr is a non-fatal error encountered signing a certificate,
// which means that the certificate issuance may be retried at a later time.
type recoverableErr struct {
err error
}
func (r recoverableErr) Error() string {
return r.err.Error()
}
// ErrNoLocalRootCA is an error type used to indicate that the local root CA
// certificate file does not exist.
var ErrNoLocalRootCA = errors.New("local root CA certificate does not exist")
// ErrNoValidSigner is an error type used to indicate that our RootCA doesn't have the ability to
// sign certificates.
var ErrNoValidSigner = recoverableErr{err: errors.New("no valid signer found")}
func init() {
cflog.Level = 5
}
// CertPaths is a helper struct that keeps track of the paths of a
// Cert and corresponding Key
type CertPaths struct {
Cert, Key string
}
// IssuerInfo contains the subject and public key of the issuer of a certificate
type IssuerInfo struct {
Subject []byte
PublicKey []byte
}
// LocalSigner is a signer that can sign CSRs
type LocalSigner struct {
cfsigner.Signer
// Key will only be used by the original manager to put the private
// key-material in raft, no signing operations depend on it.
Key []byte
// Cert is one PEM encoded Certificate used as the signing CA. It must correspond to the key.
Cert []byte
// just cached parsed values for validation, etc.
parsedCert *x509.Certificate
cryptoSigner crypto.Signer
}
type x509UnknownAuthError struct {
error
failedLeafCert *x509.Certificate
}
// RootCA is the representation of everything we need to sign certificates and/or to verify certificates
//
// RootCA.Cert: [CA cert1][CA cert2]
// RootCA.Intermediates: [intermediate CA1][intermediate CA2][intermediate CA3]
// RootCA.signer.Cert: [signing CA cert]
// RootCA.signer.Key: [signing CA key]
//
// Requirements:
//
// - [signing CA key] must be the private key for [signing CA cert], and either both or none must be provided
// - [intermediate CA1] must have the same public key and subject as [signing CA cert], because otherwise when
// appended to a leaf certificate, the intermediates will not form a chain (because [intermediate CA1] won't because
// the signer of the leaf certificate)
// - [intermediate CA1] must be signed by [intermediate CA2], which must be signed by [intermediate CA3]
// - When we issue a certificate, the intermediates will be appended so that the certificate looks like:
// [leaf signed by signing CA cert][intermediate CA1][intermediate CA2][intermediate CA3]
// - [leaf signed by signing CA cert][intermediate CA1][intermediate CA2][intermediate CA3] is guaranteed to form a
// valid chain from [leaf signed by signing CA cert] to one of the root certs ([signing CA cert], [CA cert1], [CA cert2])
// using zero or more of the intermediate certs ([intermediate CA1][intermediate CA2][intermediate CA3]) as intermediates
//
// Example 1: Simple root rotation
//
// - Initial state:
// - RootCA.Cert: [Root CA1 self-signed]
// - RootCA.Intermediates: []
// - RootCA.signer.Cert: [Root CA1 self-signed]
// - Issued TLS cert: [leaf signed by Root CA1]
//
// - Intermediate state (during root rotation):
// - RootCA.Cert: [Root CA1 self-signed]
// - RootCA.Intermediates: [Root CA2 signed by Root CA1]
// - RootCA.signer.Cert: [Root CA2 signed by Root CA1]
// - Issued TLS cert: [leaf signed by Root CA2][Root CA2 signed by Root CA1]
//
// - Final state:
// - RootCA.Cert: [Root CA2 self-signed]
// - RootCA.Intermediates: []
// - RootCA.signer.Cert: [Root CA2 self-signed]
// - Issued TLS cert: [leaf signed by Root CA2]
type RootCA struct {
// Certs contains a bundle of self-signed, PEM encoded certificates for the Root CA to be used
// as the root of trust.
Certs []byte
// Intermediates contains a bundle of PEM encoded intermediate CA certificates to append to any
// issued TLS (leaf) certificates. The first one must have the same public key and subject as the
// signing root certificate, and the rest must form a chain, each one certifying the one above it,
// as per RFC5246 section 7.4.2.
Intermediates []byte
// Pool is the root pool used to validate TLS certificates
Pool *x509.CertPool
// Digest of the serialized bytes of the certificate(s)
Digest digest.Digest
// This signer will be nil if the node doesn't have the appropriate key material
signer *LocalSigner
}
// Signer is an accessor for the local signer that returns an error if this root cannot sign.
func (rca *RootCA) Signer() (*LocalSigner, error) {
if rca.Pool == nil || rca.signer == nil || len(rca.signer.Cert) == 0 || rca.signer.Signer == nil {
return nil, ErrNoValidSigner
}
return rca.signer, nil
}
// IssueAndSaveNewCertificates generates a new key-pair, signs it with the local root-ca, and returns a
// TLS certificate and the issuer information for the certificate.
func (rca *RootCA) IssueAndSaveNewCertificates(kw KeyWriter, cn, ou, org string) (*tls.Certificate, *IssuerInfo, error) {
csr, key, err := GenerateNewCSR()
if err != nil {
return nil, nil, errors.Wrap(err, "error when generating new node certs")
}
// Obtain a signed Certificate
certChain, err := rca.ParseValidateAndSignCSR(csr, cn, ou, org)
if err != nil {
return nil, nil, errors.Wrap(err, "failed to sign node certificate")
}
signer, err := rca.Signer()
if err != nil { // should never happen, since if ParseValidateAndSignCSR did not fail this root CA must have a signer
return nil, nil, err
}
// Create a valid TLSKeyPair out of the PEM encoded private key and certificate
tlsKeyPair, err := tls.X509KeyPair(certChain, key)
if err != nil {
return nil, nil, err
}
if err := kw.Write(NormalizePEMs(certChain), key, nil); err != nil {
return nil, nil, err
}
return &tlsKeyPair, &IssuerInfo{
PublicKey: signer.parsedCert.RawSubjectPublicKeyInfo,
Subject: signer.parsedCert.RawSubject,
}, nil
}
// RequestAndSaveNewCertificates gets new certificates issued, either by signing them locally if a signer is
// available, or by requesting them from the remote server at remoteAddr. This function returns the TLS
// certificate and the issuer information for the certificate.
func (rca *RootCA) RequestAndSaveNewCertificates(ctx context.Context, kw KeyWriter, config CertificateRequestConfig) (*tls.Certificate, *IssuerInfo, error) {
// Create a new key/pair and CSR
csr, key, err := GenerateNewCSR()
if err != nil {
return nil, nil, errors.Wrap(err, "error when generating new node certs")
}
// Get the remote manager to issue a CA signed certificate for this node
// Retry up to 5 times in case the manager we first try to contact isn't
// responding properly (for example, it may have just been demoted).
var signedCert []byte
for i := 0; i != 5; i++ {
signedCert, err = GetRemoteSignedCertificate(ctx, csr, rca.Pool, config)
if err == nil {
break
}
// If the first attempt fails, we should try a remote
// connection. The local node may be a manager that was
// demoted, so the local connection (which is preferred) may
// not work. If we are successful in renewing the certificate,
// the local connection will not be returned by the connection
// broker anymore.
config.ForceRemote = true
// Wait a moment, in case a leader election was taking place.
select {
case <-time.After(config.RetryInterval):
case <-ctx.Done():
return nil, nil, ctx.Err()
}
}
if err != nil {
return nil, nil, err
}
// ÐовеÑÑй, но пÑовеÑÑй.
// Before we overwrite our local key + certificate, let's make sure the server gave us one that is valid
// Create an X509Cert so we can .Verify()
// Check to see if this certificate was signed by our CA, and isn't expired
parsedCerts, chains, err := ValidateCertChain(rca.Pool, signedCert, false)
// TODO(cyli): - right now we need the invalid certificate in order to determine whether or not we should
// download a new root, because we only want to do that in the case of workers. When we have a single
// codepath for updating the root CAs for both managers and workers, this snippet can go.
if _, ok := err.(x509.UnknownAuthorityError); ok {
if parsedCerts, parseErr := helpers.ParseCertificatesPEM(signedCert); parseErr == nil && len(parsedCerts) > 0 {
return nil, nil, x509UnknownAuthError{
error: err,
failedLeafCert: parsedCerts[0],
}
}
}
if err != nil {
return nil, nil, err
}
// ValidateChain, if successful, will always return at least 1 parsed cert and at least 1 chain containing
// at least 2 certificates: the leaf and the root.
leafCert := parsedCerts[0]
issuer := chains[0][1]
// Create a valid TLSKeyPair out of the PEM encoded private key and certificate
tlsKeyPair, err := tls.X509KeyPair(signedCert, key)
if err != nil {
return nil, nil, err
}
var kekUpdate *KEKData
for i := 0; i < 5; i++ {
// ValidateCertChain will always return at least 1 cert, so indexing at 0 is safe
kekUpdate, err = rca.getKEKUpdate(ctx, leafCert, tlsKeyPair, config)
if err == nil {
break
}
config.ForceRemote = true
// Wait a moment, in case a leader election was taking place.
select {
case <-time.After(config.RetryInterval):
case <-ctx.Done():
return nil, nil, ctx.Err()
}
}
if err != nil {
return nil, nil, err
}
if err := kw.Write(NormalizePEMs(signedCert), key, kekUpdate); err != nil {
return nil, nil, err
}
return &tlsKeyPair, &IssuerInfo{
PublicKey: issuer.RawSubjectPublicKeyInfo,
Subject: issuer.RawSubject,
}, nil
}
func (rca *RootCA) getKEKUpdate(ctx context.Context, leafCert *x509.Certificate, keypair tls.Certificate, config CertificateRequestConfig) (*KEKData, error) {
var managerRole bool
for _, ou := range leafCert.Subject.OrganizationalUnit {
if ou == ManagerRole {
managerRole = true
break
}
}
if managerRole {
mtlsCreds := credentials.NewTLS(&tls.Config{ServerName: CARole, RootCAs: rca.Pool, Certificates: []tls.Certificate{keypair}})
conn, err := getGRPCConnection(mtlsCreds, config.ConnBroker, config.ForceRemote)
if err != nil {
return nil, err
}
client := api.NewCAClient(conn.ClientConn)
ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
defer cancel()
response, err := client.GetUnlockKey(ctx, &api.GetUnlockKeyRequest{})
if err != nil {
s, _ := status.FromError(err)
if s.Code() == codes.Unimplemented { // if the server does not support keks, return as if no encryption key was specified
conn.Close(true)
return &KEKData{}, nil
}
conn.Close(false)
return nil, err
}
conn.Close(true)
return &KEKData{KEK: response.UnlockKey, Version: response.Version.Index}, nil
}
// If this is a worker, set to never encrypt. We always want to set to the lock key to nil,
// in case this was a manager that was demoted to a worker.
return &KEKData{}, nil
}
// PrepareCSR creates a CFSSL Sign Request based on the given raw CSR and
// overrides the Subject and Hosts with the given extra args.
func PrepareCSR(csrBytes []byte, cn, ou, org string) cfsigner.SignRequest {
// All managers get added the subject-alt-name of CA, so they can be
// used for cert issuance.
hosts := []string{ou, cn}
if ou == ManagerRole {
hosts = append(hosts, CARole)
}
return cfsigner.SignRequest{
Request: string(csrBytes),
// OU is used for Authentication of the node type. The CN has the random
// node ID.
Subject: &cfsigner.Subject{CN: cn, Names: []cfcsr.Name{{OU: ou, O: org}}},
// Adding ou as DNS alt name, so clients can connect to ManagerRole and CARole
Hosts: hosts,
}
}
// ParseValidateAndSignCSR returns a signed certificate from a particular rootCA and a CSR.
func (rca *RootCA) ParseValidateAndSignCSR(csrBytes []byte, cn, ou, org string) ([]byte, error) {
signRequest := PrepareCSR(csrBytes, cn, ou, org)
signer, err := rca.Signer()
if err != nil {
return nil, err
}
cert, err := signer.Sign(signRequest)
if err != nil {
return nil, errors.Wrap(err, "failed to sign node certificate")
}
return append(cert, rca.Intermediates...), nil
}
// CrossSignCACertificate takes a CA root certificate and generates an intermediate CA from it signed with the current root signer
func (rca *RootCA) CrossSignCACertificate(otherCAPEM []byte) ([]byte, error) {
signer, err := rca.Signer()
if err != nil {
return nil, err
}
// create a new cert with exactly the same parameters, including the public key and exact NotBefore and NotAfter
template, err := helpers.ParseCertificatePEM(otherCAPEM)
if err != nil {
return nil, errors.New("could not parse new CA certificate")
}
if !template.IsCA {
return nil, errors.New("certificate not a CA")
}
template.SignatureAlgorithm = signer.parsedCert.SignatureAlgorithm // make sure we can sign with the signer key
derBytes, err := x509.CreateCertificate(cryptorand.Reader, template, signer.parsedCert, template.PublicKey, signer.cryptoSigner)
if err != nil {
return nil, errors.Wrap(err, "could not cross-sign new CA certificate using old CA material")
}
return pem.EncodeToMemory(&pem.Block{
Type: "CERTIFICATE",
Bytes: derBytes,
}), nil
}
func validateSignatureAlgorithm(cert *x509.Certificate) error {
switch cert.SignatureAlgorithm {
case x509.SHA256WithRSA, x509.SHA384WithRSA, x509.SHA512WithRSA, x509.ECDSAWithSHA256, x509.ECDSAWithSHA384, x509.ECDSAWithSHA512:
return nil
default:
return fmt.Errorf("unsupported signature algorithm: %s", cert.SignatureAlgorithm.String())
}
}
// NewRootCA creates a new RootCA object from unparsed PEM cert bundle and key byte
// slices. key may be nil, and in this case NewRootCA will return a RootCA
// without a signer.
func NewRootCA(rootCertBytes, signCertBytes, signKeyBytes []byte, certExpiry time.Duration, intermediates []byte) (RootCA, error) {
// Parse all the certificates in the cert bundle
parsedCerts, err := helpers.ParseCertificatesPEM(rootCertBytes)
if err != nil {
return RootCA{}, errors.Wrap(err, "invalid root certificates")
}
// Check to see if we have at least one valid cert
if len(parsedCerts) < 1 {
return RootCA{}, errors.New("no valid root CA certificates found")
}
// Create a Pool with all of the certificates found
pool := x509.NewCertPool()
for _, cert := range parsedCerts {
if err := validateSignatureAlgorithm(cert); err != nil {
return RootCA{}, err
}
// Check to see if all of the certificates are valid, self-signed root CA certs
selfpool := x509.NewCertPool()
selfpool.AddCert(cert)
if _, err := cert.Verify(x509.VerifyOptions{Roots: selfpool}); err != nil {
return RootCA{}, errors.Wrap(err, "error while validating Root CA Certificate")
}
pool.AddCert(cert)
}
// Calculate the digest for our Root CA bundle
digest := digest.FromBytes(rootCertBytes)
// The intermediates supplied must be able to chain up to the root certificates, so that when they are appended to
// a leaf certificate, the leaf certificate can be validated through the intermediates to the root certificates.
var intermediatePool *x509.CertPool
var parsedIntermediates []*x509.Certificate
if len(intermediates) > 0 {
parsedIntermediates, _, err = ValidateCertChain(pool, intermediates, false)
if err != nil {
return RootCA{}, errors.Wrap(err, "invalid intermediate chain")
}
intermediatePool = x509.NewCertPool()
for _, cert := range parsedIntermediates {
intermediatePool.AddCert(cert)
}
}
var localSigner *LocalSigner
if len(signKeyBytes) != 0 || len(signCertBytes) != 0 {
localSigner, err = newLocalSigner(signKeyBytes, signCertBytes, certExpiry, pool, intermediatePool)
if err != nil {
return RootCA{}, err
}
// If a signer is provided and there are intermediates, then either the first intermediate would be the signer CA
// certificate (in which case it'd have the same subject and public key), or it would be a cross-signed
// intermediate with the same subject and public key as our signing CA certificate (which could be either an
// intermediate cert or a self-signed root cert).
if len(parsedIntermediates) > 0 && (!bytes.Equal(parsedIntermediates[0].RawSubject, localSigner.parsedCert.RawSubject) ||
!bytes.Equal(parsedIntermediates[0].RawSubjectPublicKeyInfo, localSigner.parsedCert.RawSubjectPublicKeyInfo)) {
return RootCA{}, errors.New(
"invalid intermediate chain - the first intermediate must have the same subject and public key as the signing cert")
}
}
return RootCA{signer: localSigner, Intermediates: intermediates, Digest: digest, Certs: rootCertBytes, Pool: pool}, nil
}
// ValidateCertChain checks checks that the certificates provided chain up to the root pool provided. In addition
// it also enforces that every cert in the bundle certificates form a chain, each one certifying the one above,
// as per RFC5246 section 7.4.2, and that every certificate (whether or not it is necessary to form a chain to the root
// pool) is currently valid and not yet expired (unless allowExpiry is set to true).
// This is additional validation not required by go's Certificate.Verify (which allows invalid certs in the
// intermediate pool), because this function is intended to be used when reading certs from untrusted locations such as
// from disk or over a network when a CSR is signed, so it is extra pedantic.
// This function always returns all the parsed certificates in the bundle in order, which means there will always be
// at least 1 certificate if there is no error, and the valid chains found by Certificate.Verify
func ValidateCertChain(rootPool *x509.CertPool, certs []byte, allowExpired bool) ([]*x509.Certificate, [][]*x509.Certificate, error) {
// Parse all the certificates in the cert bundle
parsedCerts, err := helpers.ParseCertificatesPEM(certs)
if err != nil {
return nil, nil, err
}
if len(parsedCerts) == 0 {
return nil, nil, errors.New("no certificates to validate")
}
now := time.Now()
// ensure that they form a chain, each one being signed by the one after it
var intermediatePool *x509.CertPool
for i, cert := range parsedCerts {
// Manual expiry validation because we want more information on which certificate in the chain is expired, and
// because this is an easier way to allow expired certs.
if now.Before(cert.NotBefore) {
return nil, nil, errors.Wrapf(
x509.CertificateInvalidError{
Cert: cert,
Reason: x509.Expired,
},
"certificate (%d - %s) not valid before %s, and it is currently %s",
i+1, cert.Subject.CommonName, cert.NotBefore.UTC().Format(time.RFC1123), now.Format(time.RFC1123))
}
if !allowExpired && now.After(cert.NotAfter) {
return nil, nil, errors.Wrapf(
x509.CertificateInvalidError{
Cert: cert,
Reason: x509.Expired,
},
"certificate (%d - %s) not valid after %s, and it is currently %s",
i+1, cert.Subject.CommonName, cert.NotAfter.UTC().Format(time.RFC1123), now.Format(time.RFC1123))
}
if i > 0 {
// check that the previous cert was signed by this cert
prevCert := parsedCerts[i-1]
if err := prevCert.CheckSignatureFrom(cert); err != nil {
return nil, nil, errors.Wrapf(err, "certificates do not form a chain: (%d - %s) is not signed by (%d - %s)",
i, prevCert.Subject.CommonName, i+1, cert.Subject.CommonName)
}
if intermediatePool == nil {
intermediatePool = x509.NewCertPool()
}
intermediatePool.AddCert(cert)
}
}
verifyOpts := x509.VerifyOptions{
Roots: rootPool,
Intermediates: intermediatePool,
CurrentTime: now,
}
var chains [][]*x509.Certificate
// If we accept expired certs, try to build a valid cert chain using some subset of the certs. We start off using the
// first certificate's NotAfter as the current time, thus ensuring that the first cert is not expired. If the chain
// still fails to validate due to expiry issues, continue iterating over the rest of the certs.
// If any of the other certs has an earlier NotAfter time, use that time as the current time instead. This insures that
// particular cert, and any that came before it, are not expired. Note that the root that the certs chain up to
// should also not be expired at that "current" time.
if allowExpired {
verifyOpts.CurrentTime = parsedCerts[0].NotAfter.Add(time.Hour)
for _, cert := range parsedCerts {
if !cert.NotAfter.Before(verifyOpts.CurrentTime) {
continue
}
verifyOpts.CurrentTime = cert.NotAfter
chains, err = parsedCerts[0].Verify(verifyOpts)
if err == nil {
return parsedCerts, chains, nil
}
}
if invalid, ok := err.(x509.CertificateInvalidError); ok && invalid.Reason == x509.Expired {
return nil, nil, errors.New("there is no time span for which all of the certificates, including a root, are valid")
}
return nil, nil, err
}
chains, err = parsedCerts[0].Verify(verifyOpts)
if err != nil {
return nil, nil, err
}
return parsedCerts, chains, nil
}
// newLocalSigner validates the signing cert and signing key to create a local signer, which accepts a crypto signer and a cert
func newLocalSigner(keyBytes, certBytes []byte, certExpiry time.Duration, rootPool, intermediatePool *x509.CertPool) (*LocalSigner, error) {
if len(keyBytes) == 0 || len(certBytes) == 0 {
return nil, errors.New("must provide both a signing key and a signing cert, or neither")
}
parsedCerts, err := helpers.ParseCertificatesPEM(certBytes)
if err != nil {
return nil, errors.Wrap(err, "invalid signing CA cert")
}
if len(parsedCerts) == 0 {
return nil, errors.New("no valid signing CA certificates found")
}
if err := validateSignatureAlgorithm(parsedCerts[0]); err != nil {
return nil, err
}
opts := x509.VerifyOptions{
Roots: rootPool,
Intermediates: intermediatePool,
}
if _, err := parsedCerts[0].Verify(opts); err != nil {
return nil, errors.Wrap(err, "error while validating signing CA certificate against roots and intermediates")
}
// The key should not be encrypted, but it could be in PKCS8 format rather than PKCS1
priv, err := helpers.ParsePrivateKeyPEM(keyBytes)
if err != nil {
return nil, errors.Wrap(err, "malformed private key")
}
// We will always use the first certificate inside of the root bundle as the active one
if err := ensureCertKeyMatch(parsedCerts[0], priv.Public()); err != nil {
return nil, err
}
signer, err := local.NewSigner(priv, parsedCerts[0], cfsigner.DefaultSigAlgo(priv), SigningPolicy(certExpiry))
if err != nil {
return nil, err
}
return &LocalSigner{Cert: certBytes, Key: keyBytes, Signer: signer, parsedCert: parsedCerts[0], cryptoSigner: priv}, nil
}
func ensureCertKeyMatch(cert *x509.Certificate, key crypto.PublicKey) error {
switch certPub := cert.PublicKey.(type) {
case *rsa.PublicKey:
if certPub.N.BitLen() < 2048 || certPub.E == 1 {
return errors.New("unsupported RSA key parameters")
}
rsaKey, ok := key.(*rsa.PublicKey)
if ok && certPub.E == rsaKey.E && certPub.N.Cmp(rsaKey.N) == 0 {
return nil
}
case *ecdsa.PublicKey:
switch certPub.Curve {
case elliptic.P256(), elliptic.P384(), elliptic.P521():
break
default:
return errors.New("unsupported ECDSA key parameters")
}
ecKey, ok := key.(*ecdsa.PublicKey)
if ok && certPub.X.Cmp(ecKey.X) == 0 && certPub.Y.Cmp(ecKey.Y) == 0 {
return nil
}
default:
return errors.New("unknown or unsupported certificate public key algorithm")
}
return errors.New("certificate key mismatch")
}
// GetLocalRootCA validates if the contents of the file are a valid self-signed
// CA certificate, and returns the PEM-encoded Certificate if so
func GetLocalRootCA(paths CertPaths) (RootCA, error) {
// Check if we have a Certificate file
cert, err := os.ReadFile(paths.Cert)
if err != nil {
if os.IsNotExist(err) {
err = ErrNoLocalRootCA
}
return RootCA{}, err
}
signingCert := cert
key, err := os.ReadFile(paths.Key)
if err != nil {
if !os.IsNotExist(err) {
return RootCA{}, err
}
// There may not be a local key. It's okay to pass in a nil
// key. We'll get a root CA without a signer.
key = nil
signingCert = nil
}
return NewRootCA(cert, signingCert, key, DefaultNodeCertExpiration, nil)
}
func getGRPCConnection(creds credentials.TransportCredentials, connBroker *connectionbroker.Broker, forceRemote bool) (*connectionbroker.Conn, error) {
dialOpts := []grpc.DialOption{
grpc.WithTransportCredentials(creds),
grpc.WithTimeout(5 * time.Second),
grpc.WithBackoffMaxDelay(5 * time.Second),
}
if forceRemote {
return connBroker.SelectRemote(dialOpts...)
}
return connBroker.Select(dialOpts...)
}
// GetRemoteCA returns the remote endpoint's CA certificate bundle
func GetRemoteCA(ctx context.Context, d digest.Digest, connBroker *connectionbroker.Broker) (RootCA, error) {
// This TLS Config is intentionally using InsecureSkipVerify. We use the
// digest instead to check the integrity of the CA certificate.
insecureCreds := credentials.NewTLS(&tls.Config{InsecureSkipVerify: true})
conn, err := getGRPCConnection(insecureCreds, connBroker, false)
if err != nil {
return RootCA{}, err
}
client := api.NewCAClient(conn.ClientConn)
ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
defer cancel()
defer func() {
conn.Close(err == nil)
}()
response, err := client.GetRootCACertificate(ctx, &api.GetRootCACertificateRequest{})
if err != nil {
return RootCA{}, err
}
// If a bundle of certificates are provided, the digest covers the entire bundle and not just
// one of the certificates in the bundle. Otherwise, a node can be MITMed while joining if
// the MITM CA provides a single certificate which matches the digest, and providing arbitrary
// other non-verified root certs that the manager certificate actually chains up to.
if d != "" {
verifier := d.Verifier()
if err != nil {
return RootCA{}, errors.Wrap(err, "unexpected error getting digest verifier")
}
io.Copy(verifier, bytes.NewReader(response.Certificate))
if !verifier.Verified() {
return RootCA{}, errors.Errorf("remote CA does not match fingerprint. Expected: %s", d.Encoded())
}
}
// NewRootCA will validate that the certificates are otherwise valid and create a RootCA object.
// Since there is no key, the certificate expiry does not matter and will not be used.
return NewRootCA(response.Certificate, nil, nil, DefaultNodeCertExpiration, nil)
}
// CreateRootCA creates a Certificate authority for a new Swarm Cluster, potentially
// overwriting any existing CAs.
func CreateRootCA(rootCN string) (RootCA, error) {
// Create a simple CSR for the CA using the default CA validator and policy
req := cfcsr.CertificateRequest{
CN: rootCN,
KeyRequest: &cfcsr.KeyRequest{A: RootKeyAlgo, S: RootKeySize},
CA: &cfcsr.CAConfig{Expiry: RootCAExpiration},
}
// Generate the CA and get the certificate and private key
cert, _, key, err := initca.New(&req)
if err != nil {
return RootCA{}, err
}
rootCA, err := NewRootCA(cert, cert, key, DefaultNodeCertExpiration, nil)
if err != nil {
return RootCA{}, err
}
return rootCA, nil
}
// GetRemoteSignedCertificate submits a CSR to a remote CA server address,
// and that is part of a CA identified by a specific certificate pool.
func GetRemoteSignedCertificate(ctx context.Context, csr []byte, rootCAPool *x509.CertPool, config CertificateRequestConfig) ([]byte, error) {
if rootCAPool == nil {
return nil, errors.New("valid root CA pool required")
}
creds := config.Credentials
if creds == nil {
// This is our only non-MTLS request, and it happens when we are boostraping our TLS certs
// We're using CARole as server name, so an external CA doesn't also have to have ManagerRole in the cert SANs
creds = credentials.NewTLS(&tls.Config{ServerName: CARole, RootCAs: rootCAPool})
}
conn, err := getGRPCConnection(creds, config.ConnBroker, config.ForceRemote)
if err != nil {
return nil, err
}
// Create a CAClient to retrieve a new Certificate
caClient := api.NewNodeCAClient(conn.ClientConn)
issueCtx, issueCancel := context.WithTimeout(ctx, 5*time.Second)
defer issueCancel()
// Send the Request and retrieve the request token
issueRequest := &api.IssueNodeCertificateRequest{CSR: csr, Token: config.Token, Availability: config.Availability}
issueResponse, err := caClient.IssueNodeCertificate(issueCtx, issueRequest)
if err != nil {
conn.Close(false)
return nil, err
}
statusRequest := &api.NodeCertificateStatusRequest{NodeID: issueResponse.NodeID}
expBackoff := events.NewExponentialBackoff(events.ExponentialBackoffConfig{
Base: time.Second,
Factor: time.Second,
Max: 30 * time.Second,
})
// Exponential backoff with Max of 30 seconds to wait for a new retry
for {
timeout := 5 * time.Second
if config.NodeCertificateStatusRequestTimeout > 0 {
timeout = config.NodeCertificateStatusRequestTimeout
}
// Send the Request and retrieve the certificate
stateCtx, cancel := context.WithTimeout(ctx, timeout)
defer cancel()
statusResponse, err := caClient.NodeCertificateStatus(stateCtx, statusRequest)
s, _ := status.FromError(err)
switch {
case err != nil && s.Code() != codes.DeadlineExceeded:
conn.Close(false)
// Because IssueNodeCertificate succeeded, if this call failed likely it is due to an issue with this
// particular connection, so we need to get another. We should try a remote connection - the local node
// may be a manager that was demoted, so the local connection (which is preferred) may not work.
config.ForceRemote = true
conn, err = getGRPCConnection(creds, config.ConnBroker, config.ForceRemote)
if err != nil {
return nil, err
}
caClient = api.NewNodeCAClient(conn.ClientConn)
// If there was no deadline exceeded error, and the certificate was issued, return
case err == nil && (statusResponse.Status.State == api.IssuanceStateIssued || statusResponse.Status.State == api.IssuanceStateRotate):
if statusResponse.Certificate == nil {
conn.Close(false)
return nil, errors.New("no certificate in CertificateStatus response")
}
// The certificate in the response must match the CSR
// we submitted. If we are getting a response for a
// certificate that was previously issued, we need to
// retry until the certificate gets updated per our
// current request.
if bytes.Equal(statusResponse.Certificate.CSR, csr) {
conn.Close(true)
return statusResponse.Certificate.Certificate, nil
}
}
// If NodeCertificateStatus timed out, we're still pending, the issuance failed, or
// the state is unknown let's continue trying after an exponential backoff
expBackoff.Failure(nil, nil)
select {
case <-ctx.Done():
conn.Close(true)
return nil, err
case <-time.After(expBackoff.Proceed(nil)):
}
}
}
// readCertValidity returns the certificate issue and expiration time
func readCertValidity(kr KeyReader) (time.Time, time.Time, error) {
var zeroTime time.Time
// Read the Cert
cert, _, err := kr.Read()
if err != nil {
return zeroTime, zeroTime, err
}
// Create an x509 certificate out of the contents on disk
certBlock, _ := pem.Decode(cert)
if certBlock == nil {
return zeroTime, zeroTime, errors.New("failed to decode certificate block")
}
X509Cert, err := x509.ParseCertificate(certBlock.Bytes)
if err != nil {
return zeroTime, zeroTime, err
}
return X509Cert.NotBefore, X509Cert.NotAfter, nil
}
// SaveRootCA saves a RootCA object to disk
func SaveRootCA(rootCA RootCA, paths CertPaths) error {
// Make sure the necessary dirs exist and they are writable
err := os.MkdirAll(filepath.Dir(paths.Cert), 0o755)
if err != nil {
return err
}
// If the root certificate got returned successfully, save the rootCA to disk.
return ioutils.AtomicWriteFile(paths.Cert, rootCA.Certs, 0o644)
}
// GenerateNewCSR returns a newly generated key and CSR signed with said key
func GenerateNewCSR() ([]byte, []byte, error) {
req := &cfcsr.CertificateRequest{
KeyRequest: cfcsr.NewKeyRequest(),
}
csr, key, err := cfcsr.ParseRequest(req)
if err != nil {
return nil, nil, err
}
key, err = pkcs8.ConvertECPrivateKeyPEM(key)
return csr, key, err
}
// NormalizePEMs takes a bundle of PEM-encoded certificates in a certificate bundle,
// decodes them, removes headers, and re-encodes them to make sure that they have
// consistent whitespace. Note that this is intended to normalize x509 certificates
// in PEM format, hence the stripping out of headers.
func NormalizePEMs(certs []byte) []byte {
var (
results []byte
pemBlock *pem.Block
)
for {
pemBlock, certs = pem.Decode(bytes.TrimSpace(certs))
if pemBlock == nil {
return results
}
pemBlock.Headers = nil
results = append(results, pem.EncodeToMemory(pemBlock)...)
}
}