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