mirror of https://github.com/hashicorp/consul
383 lines
10 KiB
Go
383 lines
10 KiB
Go
package ca
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import (
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"bytes"
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"crypto/rand"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/pem"
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"fmt"
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"math/big"
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"net/url"
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"sync"
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"time"
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"github.com/hashicorp/consul/agent/connect"
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"github.com/hashicorp/consul/agent/consul/state"
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"github.com/hashicorp/consul/agent/structs"
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)
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type ConsulProvider struct {
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config *structs.ConsulCAProviderConfig
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id string
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delegate ConsulProviderStateDelegate
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sync.RWMutex
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}
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type ConsulProviderStateDelegate interface {
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State() *state.Store
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ApplyCARequest(*structs.CARequest) error
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}
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// NewConsulProvider returns a new instance of the Consul CA provider,
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// bootstrapping its state in the state store necessary
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func NewConsulProvider(rawConfig map[string]interface{}, delegate ConsulProviderStateDelegate) (*ConsulProvider, error) {
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conf, err := ParseConsulCAConfig(rawConfig)
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if err != nil {
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return nil, err
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}
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provider := &ConsulProvider{
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config: conf,
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delegate: delegate,
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id: fmt.Sprintf("%s,%s", conf.PrivateKey, conf.RootCert),
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}
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// Check if this configuration of the provider has already been
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// initialized in the state store.
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state := delegate.State()
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_, providerState, err := state.CAProviderState(provider.id)
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if err != nil {
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return nil, err
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}
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// Exit early if the state store has already been populated for this config.
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if providerState != nil {
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return provider, nil
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}
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newState := structs.CAConsulProviderState{
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ID: provider.id,
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}
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// Write the initial provider state to get the index to use for the
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// CA serial number.
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{
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args := &structs.CARequest{
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Op: structs.CAOpSetProviderState,
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ProviderState: &newState,
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}
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if err := delegate.ApplyCARequest(args); err != nil {
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return nil, err
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}
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}
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idx, _, err := state.CAProviderState(provider.id)
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if err != nil {
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return nil, err
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}
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// Generate a private key if needed
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if conf.PrivateKey == "" {
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_, pk, err := connect.GeneratePrivateKey()
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if err != nil {
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return nil, err
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}
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newState.PrivateKey = pk
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} else {
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newState.PrivateKey = conf.PrivateKey
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}
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// Generate the root CA if necessary
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if conf.RootCert == "" {
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ca, err := provider.generateCA(newState.PrivateKey, idx+1)
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if err != nil {
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return nil, fmt.Errorf("error generating CA: %v", err)
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}
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newState.RootCert = ca
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} else {
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newState.RootCert = conf.RootCert
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}
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// Write the provider state
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args := &structs.CARequest{
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Op: structs.CAOpSetProviderState,
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ProviderState: &newState,
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}
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if err := delegate.ApplyCARequest(args); err != nil {
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return nil, err
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}
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return provider, nil
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}
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// Return the active root CA and generate a new one if needed
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func (c *ConsulProvider) ActiveRoot() (string, error) {
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state := c.delegate.State()
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_, providerState, err := state.CAProviderState(c.id)
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if err != nil {
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return "", err
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}
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return providerState.RootCert, nil
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}
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// We aren't maintaining separate root/intermediate CAs for the builtin
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// provider, so just return the root.
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func (c *ConsulProvider) ActiveIntermediate() (string, error) {
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return c.ActiveRoot()
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}
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// We aren't maintaining separate root/intermediate CAs for the builtin
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// provider, so just return the root.
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func (c *ConsulProvider) GenerateIntermediate() (string, error) {
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return c.ActiveIntermediate()
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}
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// Remove the state store entry for this provider instance.
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func (c *ConsulProvider) Cleanup() error {
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args := &structs.CARequest{
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Op: structs.CAOpDeleteProviderState,
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ProviderState: &structs.CAConsulProviderState{ID: c.id},
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}
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if err := c.delegate.ApplyCARequest(args); err != nil {
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return err
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}
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return nil
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}
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// Sign returns a new certificate valid for the given SpiffeIDService
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// using the current CA.
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func (c *ConsulProvider) Sign(csr *x509.CertificateRequest) (string, error) {
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// Lock during the signing so we don't use the same index twice
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// for different cert serial numbers.
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c.Lock()
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defer c.Unlock()
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// Get the provider state
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state := c.delegate.State()
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idx, providerState, err := state.CAProviderState(c.id)
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if err != nil {
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return "", err
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}
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// Create the keyId for the cert from the signing private key.
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signer, err := connect.ParseSigner(providerState.PrivateKey)
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if err != nil {
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return "", err
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}
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if signer == nil {
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return "", fmt.Errorf("error signing cert: Consul CA not initialized yet")
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}
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keyId, err := connect.KeyId(signer.Public())
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if err != nil {
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return "", err
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}
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// Parse the SPIFFE ID
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spiffeId, err := connect.ParseCertURI(csr.URIs[0])
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if err != nil {
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return "", err
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}
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serviceId, ok := spiffeId.(*connect.SpiffeIDService)
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if !ok {
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return "", fmt.Errorf("SPIFFE ID in CSR must be a service ID")
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}
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// Parse the CA cert
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caCert, err := connect.ParseCert(providerState.RootCert)
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if err != nil {
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return "", fmt.Errorf("error parsing CA cert: %s", err)
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}
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// Cert template for generation
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sn := &big.Int{}
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sn.SetUint64(idx + 1)
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// Sign the certificate valid from 1 minute in the past, this helps it be
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// accepted right away even when nodes are not in close time sync accross the
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// cluster. A minute is more than enough for typical DC clock drift.
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effectiveNow := time.Now().Add(-1 * time.Minute)
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template := x509.Certificate{
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SerialNumber: sn,
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Subject: pkix.Name{CommonName: serviceId.Service},
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URIs: csr.URIs,
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Signature: csr.Signature,
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SignatureAlgorithm: csr.SignatureAlgorithm,
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PublicKeyAlgorithm: csr.PublicKeyAlgorithm,
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PublicKey: csr.PublicKey,
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BasicConstraintsValid: true,
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KeyUsage: x509.KeyUsageDataEncipherment |
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x509.KeyUsageKeyAgreement |
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x509.KeyUsageDigitalSignature |
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x509.KeyUsageKeyEncipherment,
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ExtKeyUsage: []x509.ExtKeyUsage{
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x509.ExtKeyUsageClientAuth,
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x509.ExtKeyUsageServerAuth,
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},
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// todo(kyhavlov): add a way to set the cert lifetime here from the CA config
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NotAfter: effectiveNow.Add(3 * 24 * time.Hour),
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NotBefore: effectiveNow,
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AuthorityKeyId: keyId,
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SubjectKeyId: keyId,
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}
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// Create the certificate, PEM encode it and return that value.
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var buf bytes.Buffer
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bs, err := x509.CreateCertificate(
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rand.Reader, &template, caCert, csr.PublicKey, signer)
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if err != nil {
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return "", fmt.Errorf("error generating certificate: %s", err)
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}
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err = pem.Encode(&buf, &pem.Block{Type: "CERTIFICATE", Bytes: bs})
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if err != nil {
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return "", fmt.Errorf("error encoding certificate: %s", err)
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}
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err = c.incrementProviderIndex(providerState)
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if err != nil {
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return "", err
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}
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// Set the response
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return buf.String(), nil
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}
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// CrossSignCA returns the given intermediate CA cert signed by the current active root.
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func (c *ConsulProvider) CrossSignCA(cert *x509.Certificate) (string, error) {
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c.Lock()
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defer c.Unlock()
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// Get the provider state
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state := c.delegate.State()
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idx, providerState, err := state.CAProviderState(c.id)
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if err != nil {
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return "", err
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}
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privKey, err := connect.ParseSigner(providerState.PrivateKey)
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if err != nil {
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return "", fmt.Errorf("error parsing private key %q: %s", providerState.PrivateKey, err)
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}
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rootCA, err := connect.ParseCert(providerState.RootCert)
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if err != nil {
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return "", err
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}
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keyId, err := connect.KeyId(privKey.Public())
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if err != nil {
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return "", err
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}
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// Create the cross-signing template from the existing root CA
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serialNum := &big.Int{}
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serialNum.SetUint64(idx + 1)
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template := *cert
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template.SerialNumber = serialNum
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template.SignatureAlgorithm = rootCA.SignatureAlgorithm
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template.SubjectKeyId = keyId
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template.AuthorityKeyId = keyId
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// Sign the certificate valid from 1 minute in the past, this helps it be
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// accepted right away even when nodes are not in close time sync accross the
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// cluster. A minute is more than enough for typical DC clock drift.
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effectiveNow := time.Now().Add(-1 * time.Minute)
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template.NotBefore = effectiveNow
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// This cross-signed cert is only needed during rotation, and only while old
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// leaf certs are still in use. They expire within 3 days currently so 7 is
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// safe. TODO(banks): make this be based on leaf expiry time when that is
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// configurable.
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template.NotAfter = effectiveNow.Add(7 * 24 * time.Hour)
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bs, err := x509.CreateCertificate(
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rand.Reader, &template, rootCA, cert.PublicKey, privKey)
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if err != nil {
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return "", fmt.Errorf("error generating CA certificate: %s", err)
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}
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var buf bytes.Buffer
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err = pem.Encode(&buf, &pem.Block{Type: "CERTIFICATE", Bytes: bs})
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if err != nil {
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return "", fmt.Errorf("error encoding private key: %s", err)
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}
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err = c.incrementProviderIndex(providerState)
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if err != nil {
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return "", err
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}
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return buf.String(), nil
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}
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// incrementProviderIndex does a write to increment the provider state store table index
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// used for serial numbers when generating certificates.
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func (c *ConsulProvider) incrementProviderIndex(providerState *structs.CAConsulProviderState) error {
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newState := *providerState
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args := &structs.CARequest{
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Op: structs.CAOpSetProviderState,
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ProviderState: &newState,
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}
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if err := c.delegate.ApplyCARequest(args); err != nil {
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return err
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}
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return nil
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}
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// generateCA makes a new root CA using the current private key
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func (c *ConsulProvider) generateCA(privateKey string, sn uint64) (string, error) {
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state := c.delegate.State()
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_, config, err := state.CAConfig()
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if err != nil {
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return "", err
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}
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privKey, err := connect.ParseSigner(privateKey)
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if err != nil {
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return "", fmt.Errorf("error parsing private key %q: %s", privateKey, err)
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}
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name := fmt.Sprintf("Consul CA %d", sn)
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// The URI (SPIFFE compatible) for the cert
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id := connect.SpiffeIDSigningForCluster(config)
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keyId, err := connect.KeyId(privKey.Public())
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if err != nil {
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return "", err
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}
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// Create the CA cert
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serialNum := &big.Int{}
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serialNum.SetUint64(sn)
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template := x509.Certificate{
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SerialNumber: serialNum,
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Subject: pkix.Name{CommonName: name},
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URIs: []*url.URL{id.URI()},
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PermittedDNSDomainsCritical: true,
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PermittedDNSDomains: []string{id.URI().Hostname()},
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BasicConstraintsValid: true,
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KeyUsage: x509.KeyUsageCertSign |
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x509.KeyUsageCRLSign |
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x509.KeyUsageDigitalSignature,
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IsCA: true,
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NotAfter: time.Now().Add(10 * 365 * 24 * time.Hour),
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NotBefore: time.Now(),
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AuthorityKeyId: keyId,
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SubjectKeyId: keyId,
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}
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bs, err := x509.CreateCertificate(
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rand.Reader, &template, &template, privKey.Public(), privKey)
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if err != nil {
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return "", fmt.Errorf("error generating CA certificate: %s", err)
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}
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var buf bytes.Buffer
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err = pem.Encode(&buf, &pem.Block{Type: "CERTIFICATE", Bytes: bs})
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if err != nil {
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return "", fmt.Errorf("error encoding private key: %s", err)
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}
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return buf.String(), nil
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}
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