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provider_vault.go
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provider_vault.go
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package ca
import (
"bytes"
"crypto/x509"
"encoding/pem"
"fmt"
"io/ioutil"
"net/http"
"strings"
"github.com/hashicorp/consul/agent/connect"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/go-uuid"
vaultapi "github.com/hashicorp/vault/api"
"github.com/mitchellh/mapstructure"
)
const VaultCALeafCertRole = "leaf-cert"
var ErrBackendNotMounted = fmt.Errorf("backend not mounted")
var ErrBackendNotInitialized = fmt.Errorf("backend not initialized")
type VaultProvider struct {
config *structs.VaultCAProviderConfig
client *vaultapi.Client
isRoot bool
clusterId string
}
func vaultTLSConfig(config *structs.VaultCAProviderConfig) *vaultapi.TLSConfig {
return &vaultapi.TLSConfig{
CACert: config.CAFile,
CAPath: config.CAPath,
ClientCert: config.CertFile,
ClientKey: config.KeyFile,
Insecure: config.TLSSkipVerify,
TLSServerName: config.TLSServerName,
}
}
// Configure sets up the provider using the given configuration.
func (v *VaultProvider) Configure(clusterId string, isRoot bool, rawConfig map[string]interface{}) error {
config, err := ParseVaultCAConfig(rawConfig)
if err != nil {
return err
}
clientConf := &vaultapi.Config{
Address: config.Address,
}
err = clientConf.ConfigureTLS(vaultTLSConfig(config))
if err != nil {
return err
}
client, err := vaultapi.NewClient(clientConf)
if err != nil {
return err
}
client.SetToken(config.Token)
v.config = config
v.client = client
v.isRoot = isRoot
v.clusterId = clusterId
return nil
}
// ActiveRoot returns the active root CA certificate.
func (v *VaultProvider) ActiveRoot() (string, error) {
return v.getCA(v.config.RootPKIPath)
}
// GenerateRoot mounts and initializes a new root PKI backend if needed.
func (v *VaultProvider) GenerateRoot() error {
if !v.isRoot {
return fmt.Errorf("provider is not the root certificate authority")
}
// Set up the root PKI backend if necessary.
_, err := v.ActiveRoot()
switch err {
case ErrBackendNotMounted:
err := v.client.Sys().Mount(v.config.RootPKIPath, &vaultapi.MountInput{
Type: "pki",
Description: "root CA backend for Consul Connect",
Config: vaultapi.MountConfigInput{
MaxLeaseTTL: "8760h",
},
})
if err != nil {
return err
}
fallthrough
case ErrBackendNotInitialized:
spiffeID := connect.SpiffeIDSigning{ClusterID: v.clusterId, Domain: "consul"}
uuid, err := uuid.GenerateUUID()
if err != nil {
return err
}
_, err = v.client.Logical().Write(v.config.RootPKIPath+"root/generate/internal", map[string]interface{}{
"common_name": fmt.Sprintf("Vault CA Root Authority %s", uuid),
"uri_sans": spiffeID.URI().String(),
})
if err != nil {
return err
}
default:
if err != nil {
return err
}
}
return nil
}
// GenerateIntermediateCSR creates a private key and generates a CSR
// for another datacenter's root to sign, overwriting the intermediate backend
// in the process.
func (v *VaultProvider) GenerateIntermediateCSR() (string, error) {
if v.isRoot {
return "", fmt.Errorf("provider is the root certificate authority, " +
"cannot generate an intermediate CSR")
}
return v.generateIntermediateCSR()
}
func (v *VaultProvider) generateIntermediateCSR() (string, error) {
mounts, err := v.client.Sys().ListMounts()
if err != nil {
return "", err
}
// Mount the backend if it isn't mounted already.
if _, ok := mounts[v.config.IntermediatePKIPath]; !ok {
err := v.client.Sys().Mount(v.config.IntermediatePKIPath, &vaultapi.MountInput{
Type: "pki",
Description: "intermediate CA backend for Consul Connect",
Config: vaultapi.MountConfigInput{
MaxLeaseTTL: "2160h",
},
})
if err != nil {
return "", err
}
}
// Create the role for issuing leaf certs if it doesn't exist yet
rolePath := v.config.IntermediatePKIPath + "roles/" + VaultCALeafCertRole
role, err := v.client.Logical().Read(rolePath)
if err != nil {
return "", err
}
spiffeID := connect.SpiffeIDSigning{ClusterID: v.clusterId, Domain: "consul"}
if role == nil {
_, err := v.client.Logical().Write(rolePath, map[string]interface{}{
"allow_any_name": true,
"allowed_uri_sans": "spiffe://*",
"key_type": "any",
"max_ttl": v.config.LeafCertTTL.String(),
"no_store": true,
"require_cn": false,
})
if err != nil {
return "", err
}
}
// Generate a new intermediate CSR for the root to sign.
data, err := v.client.Logical().Write(v.config.IntermediatePKIPath+"intermediate/generate/internal", map[string]interface{}{
"common_name": "Vault CA Intermediate Authority",
"key_bits": 224,
"key_type": "ec",
"uri_sans": spiffeID.URI().String(),
})
if err != nil {
return "", err
}
if data == nil || data.Data["csr"] == "" {
return "", fmt.Errorf("got empty value when generating intermediate CSR")
}
csr, ok := data.Data["csr"].(string)
if !ok {
return "", fmt.Errorf("csr result is not a string")
}
return csr, nil
}
// SetIntermediate writes the incoming intermediate and root certificates to the
// intermediate backend (as a chain).
func (v *VaultProvider) SetIntermediate(intermediatePEM, rootPEM string) error {
if v.isRoot {
return fmt.Errorf("cannot set an intermediate using another root in the primary datacenter")
}
_, err := v.client.Logical().Write(v.config.IntermediatePKIPath+"intermediate/set-signed", map[string]interface{}{
"certificate": fmt.Sprintf("%s\n%s", intermediatePEM, rootPEM),
})
if err != nil {
return err
}
return nil
}
// ActiveIntermediate returns the current intermediate certificate.
func (v *VaultProvider) ActiveIntermediate() (string, error) {
return v.getCA(v.config.IntermediatePKIPath)
}
// getCA returns the raw CA cert for the given endpoint if there is one.
// We have to use the raw NewRequest call here instead of Logical().Read
// because the endpoint only returns the raw PEM contents of the CA cert
// and not the typical format of the secrets endpoints.
func (v *VaultProvider) getCA(path string) (string, error) {
req := v.client.NewRequest("GET", "/v1/"+path+"/ca/pem")
resp, err := v.client.RawRequest(req)
if resp != nil {
defer resp.Body.Close()
}
if resp != nil && resp.StatusCode == http.StatusNotFound {
return "", ErrBackendNotMounted
}
if err != nil {
return "", err
}
bytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
return "", err
}
root := string(bytes)
if root == "" {
return "", ErrBackendNotInitialized
}
return root, nil
}
// GenerateIntermediate mounts the configured intermediate PKI backend if
// necessary, then generates and signs a new CA CSR using the root PKI backend
// and updates the intermediate backend to use that new certificate.
func (v *VaultProvider) GenerateIntermediate() (string, error) {
csr, err := v.generateIntermediateCSR()
if err != nil {
return "", err
}
// Sign the CSR with the root backend.
intermediate, err := v.client.Logical().Write(v.config.RootPKIPath+"root/sign-intermediate", map[string]interface{}{
"csr": csr,
"format": "pem_bundle",
})
if err != nil {
return "", err
}
if intermediate == nil || intermediate.Data["certificate"] == "" {
return "", fmt.Errorf("got empty value when generating intermediate certificate")
}
// Set the intermediate backend to use the new certificate.
_, err = v.client.Logical().Write(v.config.IntermediatePKIPath+"intermediate/set-signed", map[string]interface{}{
"certificate": intermediate.Data["certificate"],
})
if err != nil {
return "", err
}
return v.ActiveIntermediate()
}
// Sign calls the configured role in the intermediate PKI backend to issue
// a new leaf certificate based on the provided CSR, with the issuing
// intermediate CA cert attached.
func (v *VaultProvider) Sign(csr *x509.CertificateRequest) (string, error) {
var pemBuf bytes.Buffer
if err := pem.Encode(&pemBuf, &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: csr.Raw}); err != nil {
return "", err
}
// Use the leaf cert role to sign a new cert for this CSR.
response, err := v.client.Logical().Write(v.config.IntermediatePKIPath+"sign/"+VaultCALeafCertRole, map[string]interface{}{
"csr": pemBuf.String(),
"ttl": v.config.LeafCertTTL.String(),
})
if err != nil {
return "", fmt.Errorf("error issuing cert: %v", err)
}
if response == nil || response.Data["certificate"] == "" || response.Data["issuing_ca"] == "" {
return "", fmt.Errorf("certificate info returned from Vault was blank")
}
cert, ok := response.Data["certificate"].(string)
if !ok {
return "", fmt.Errorf("certificate was not a string")
}
ca, ok := response.Data["issuing_ca"].(string)
if !ok {
return "", fmt.Errorf("issuing_ca was not a string")
}
return fmt.Sprintf("%s\n%s", cert, ca), nil
}
// SignIntermediate returns a signed CA certificate with a path length constraint
// of 0 to ensure that the certificate cannot be used to generate further CA certs.
func (v *VaultProvider) SignIntermediate(csr *x509.CertificateRequest) (string, error) {
var pemBuf bytes.Buffer
err := pem.Encode(&pemBuf, &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: csr.Raw})
if err != nil {
return "", err
}
// Sign the CSR with the root backend.
data, err := v.client.Logical().Write(v.config.RootPKIPath+"root/sign-intermediate", map[string]interface{}{
"csr": pemBuf.String(),
"format": "pem_bundle",
"max_path_length": 0,
})
if err != nil {
return "", err
}
if data == nil || data.Data["certificate"] == "" {
return "", fmt.Errorf("got empty value when generating intermediate certificate")
}
intermediate, ok := data.Data["certificate"].(string)
if !ok {
return "", fmt.Errorf("signed intermediate result is not a string")
}
return intermediate, nil
}
// CrossSignCA takes a CA certificate and cross-signs it to form a trust chain
// back to our active root.
func (v *VaultProvider) CrossSignCA(cert *x509.Certificate) (string, error) {
var pemBuf bytes.Buffer
err := pem.Encode(&pemBuf, &pem.Block{Type: "CERTIFICATE", Bytes: cert.Raw})
if err != nil {
return "", err
}
// Have the root PKI backend sign this cert.
response, err := v.client.Logical().Write(v.config.RootPKIPath+"root/sign-self-issued", map[string]interface{}{
"certificate": pemBuf.String(),
})
if err != nil {
return "", fmt.Errorf("error having Vault cross-sign cert: %v", err)
}
if response == nil || response.Data["certificate"] == "" {
return "", fmt.Errorf("certificate info returned from Vault was blank")
}
xcCert, ok := response.Data["certificate"].(string)
if !ok {
return "", fmt.Errorf("certificate was not a string")
}
return xcCert, nil
}
// Cleanup unmounts the configured intermediate PKI backend. It's fine to tear
// this down and recreate it on small config changes because the intermediate
// certs get bundled with the leaf certs, so there's no cost to the CA changing.
func (v *VaultProvider) Cleanup() error {
return v.client.Sys().Unmount(v.config.IntermediatePKIPath)
}
func ParseVaultCAConfig(raw map[string]interface{}) (*structs.VaultCAProviderConfig, error) {
config := structs.VaultCAProviderConfig{
CommonCAProviderConfig: defaultCommonConfig(),
}
decodeConf := &mapstructure.DecoderConfig{
DecodeHook: structs.ParseDurationFunc(),
Result: &config,
WeaklyTypedInput: true,
}
decoder, err := mapstructure.NewDecoder(decodeConf)
if err != nil {
return nil, err
}
if err := decoder.Decode(raw); err != nil {
return nil, fmt.Errorf("error decoding config: %s", err)
}
if config.Token == "" {
return nil, fmt.Errorf("must provide a Vault token")
}
if config.RootPKIPath == "" {
return nil, fmt.Errorf("must provide a valid path to a root PKI backend")
}
if !strings.HasSuffix(config.RootPKIPath, "/") {
config.RootPKIPath += "/"
}
if config.IntermediatePKIPath == "" {
return nil, fmt.Errorf("must provide a valid path for the intermediate PKI backend")
}
if !strings.HasSuffix(config.IntermediatePKIPath, "/") {
config.IntermediatePKIPath += "/"
}
if err := config.CommonCAProviderConfig.Validate(); err != nil {
return nil, err
}
return &config, nil
}