boulder/ca/certificate-authority.go

434 lines
14 KiB
Go

// Copyright 2014 ISRG. All rights reserved
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
package ca
import (
"crypto"
"crypto/x509"
"encoding/json"
"encoding/pem"
"errors"
"fmt"
"io/ioutil"
"time"
"github.com/letsencrypt/boulder/Godeps/_workspace/src/github.com/jmhodges/clock"
"github.com/letsencrypt/boulder/cmd"
"github.com/letsencrypt/boulder/core"
blog "github.com/letsencrypt/boulder/log"
cfsslConfig "github.com/letsencrypt/boulder/Godeps/_workspace/src/github.com/cloudflare/cfssl/config"
"github.com/letsencrypt/boulder/Godeps/_workspace/src/github.com/cloudflare/cfssl/crypto/pkcs11key"
"github.com/letsencrypt/boulder/Godeps/_workspace/src/github.com/cloudflare/cfssl/helpers"
"github.com/letsencrypt/boulder/Godeps/_workspace/src/github.com/cloudflare/cfssl/ocsp"
"github.com/letsencrypt/boulder/Godeps/_workspace/src/github.com/cloudflare/cfssl/signer"
"github.com/letsencrypt/boulder/Godeps/_workspace/src/github.com/cloudflare/cfssl/signer/local"
)
// This map is used to detect algorithms in crypto/x509 that
// are no longer considered sufficiently strong.
// * No MD2, MD5, or SHA-1
// * No DSA
//
// SHA1WithRSA is allowed because there's still a fair bit of it
// out there, but we should try to remove it soon.
var badSignatureAlgorithms = map[x509.SignatureAlgorithm]bool{
x509.UnknownSignatureAlgorithm: true,
x509.MD2WithRSA: true,
x509.MD5WithRSA: true,
x509.DSAWithSHA1: true,
x509.DSAWithSHA256: true,
x509.ECDSAWithSHA1: true,
}
// CertificateAuthorityImpl represents a CA that signs certificates, CRLs, and
// OCSP responses.
type CertificateAuthorityImpl struct {
profile string
Signer signer.Signer
OCSPSigner ocsp.Signer
SA core.StorageAuthority
PA core.PolicyAuthority
DB core.CertificateAuthorityDatabase
Clk clock.Clock // TODO(jmhodges): should be private, like log
log *blog.AuditLogger
Prefix int // Prepended to the serial number
ValidityPeriod time.Duration
NotAfter time.Time
MaxNames int
}
// NewCertificateAuthorityImpl creates a CA that talks to a remote CFSSL
// instance. (To use a local signer, simply instantiate CertificateAuthorityImpl
// directly.) Communications with the CA are authenticated with MACs,
// using CFSSL's authenticated signature scheme. A CA created in this way
// issues for a single profile on the remote signer, which is indicated
// by name in this constructor.
func NewCertificateAuthorityImpl(cadb core.CertificateAuthorityDatabase, config cmd.CAConfig, clk clock.Clock, issuerCert string) (*CertificateAuthorityImpl, error) {
var ca *CertificateAuthorityImpl
var err error
logger := blog.GetAuditLogger()
logger.Notice("Certificate Authority Starting")
if config.SerialPrefix <= 0 || config.SerialPrefix >= 256 {
err = errors.New("Must have a positive non-zero serial prefix less than 256 for CA.")
return nil, err
}
// CFSSL requires processing JSON configs through its own LoadConfig, so we
// serialize and then deserialize.
cfsslJSON, err := json.Marshal(config.CFSSL)
if err != nil {
return nil, err
}
cfsslConfigObj, err := cfsslConfig.LoadConfig(cfsslJSON)
if err != nil {
return nil, err
}
// Load the private key, which can be a file or a PKCS#11 key.
priv, err := loadKey(config.Key)
if err != nil {
return nil, err
}
issuer, err := loadIssuer(issuerCert)
if err != nil {
return nil, err
}
signer, err := local.NewSigner(priv, issuer, x509.SHA256WithRSA, cfsslConfigObj.Signing)
if err != nil {
return nil, err
}
if config.LifespanOCSP == "" {
return nil, errors.New("Config must specify an OCSP lifespan period.")
}
lifespanOCSP, err := time.ParseDuration(config.LifespanOCSP)
if err != nil {
return nil, err
}
// Set up our OCSP signer. Note this calls for both the issuer cert and the
// OCSP signing cert, which are the same in our case.
ocspSigner, err := ocsp.NewSigner(issuer, issuer, priv, lifespanOCSP)
if err != nil {
return nil, err
}
ca = &CertificateAuthorityImpl{
Signer: signer,
OCSPSigner: ocspSigner,
profile: config.Profile,
DB: cadb,
Prefix: config.SerialPrefix,
Clk: clk,
log: logger,
NotAfter: issuer.NotAfter,
}
if config.Expiry == "" {
return nil, errors.New("Config must specify an expiry period.")
}
ca.ValidityPeriod, err = time.ParseDuration(config.Expiry)
if err != nil {
return nil, err
}
ca.MaxNames = config.MaxNames
return ca, nil
}
func loadKey(keyConfig cmd.KeyConfig) (priv crypto.Signer, err error) {
if keyConfig.File != "" {
var keyBytes []byte
keyBytes, err = ioutil.ReadFile(keyConfig.File)
if err != nil {
return nil, fmt.Errorf("Could not read key file %s", keyConfig.File)
}
priv, err = helpers.ParsePrivateKeyPEM(keyBytes)
return
}
pkcs11Config := keyConfig.PKCS11
priv, err = pkcs11key.New(pkcs11Config.Module,
pkcs11Config.Token, pkcs11Config.PIN, pkcs11Config.Label)
return
}
func loadIssuer(filename string) (issuerCert *x509.Certificate, err error) {
if filename == "" {
err = errors.New("Issuer certificate was not provided in config.")
return
}
issuerCertPEM, err := ioutil.ReadFile(filename)
if err != nil {
return
}
issuerCert, err = helpers.ParseCertificatePEM(issuerCertPEM)
return
}
// GenerateOCSP produces a new OCSP response and returns it
func (ca *CertificateAuthorityImpl) GenerateOCSP(xferObj core.OCSPSigningRequest) ([]byte, error) {
cert, err := x509.ParseCertificate(xferObj.CertDER)
if err != nil {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.AuditErr(err)
return nil, err
}
signRequest := ocsp.SignRequest{
Certificate: cert,
Status: xferObj.Status,
Reason: int(xferObj.Reason),
RevokedAt: xferObj.RevokedAt,
}
ocspResponse, err := ca.OCSPSigner.Sign(signRequest)
return ocspResponse, err
}
// RevokeCertificate revokes the trust of the Cert referred to by the provided Serial.
func (ca *CertificateAuthorityImpl) RevokeCertificate(serial string, reasonCode core.RevocationCode) (err error) {
coreCert, err := ca.SA.GetCertificate(serial)
if err != nil {
// AUDIT[ Revocation Requests ] 4e85d791-09c0-4ab3-a837-d3d67e945134
ca.log.AuditErr(err)
return err
}
cert, err := x509.ParseCertificate(coreCert.DER)
if err != nil {
// AUDIT[ Revocation Requests ] 4e85d791-09c0-4ab3-a837-d3d67e945134
ca.log.AuditErr(err)
return err
}
signRequest := ocsp.SignRequest{
Certificate: cert,
Status: string(core.OCSPStatusRevoked),
Reason: int(reasonCode),
RevokedAt: ca.Clk.Now(),
}
ocspResponse, err := ca.OCSPSigner.Sign(signRequest)
if err != nil {
// AUDIT[ Revocation Requests ] 4e85d791-09c0-4ab3-a837-d3d67e945134
ca.log.AuditErr(err)
return err
}
err = ca.SA.MarkCertificateRevoked(serial, ocspResponse, reasonCode)
return err
}
// IssueCertificate attempts to convert a CSR into a signed Certificate, while
// enforcing all policies.
func (ca *CertificateAuthorityImpl) IssueCertificate(csr x509.CertificateRequest, regID int64, earliestExpiry time.Time) (core.Certificate, error) {
emptyCert := core.Certificate{}
var err error
key, ok := csr.PublicKey.(crypto.PublicKey)
if !ok {
err = fmt.Errorf("Invalid public key in CSR.")
// AUDIT[ Certificate Requests ] 11917fa4-10ef-4e0d-9105-bacbe7836a3c
ca.log.AuditErr(err)
return emptyCert, err
}
if err = core.GoodKey(key); err != nil {
err = fmt.Errorf("Invalid public key in CSR: %s", err.Error())
// AUDIT[ Certificate Requests ] 11917fa4-10ef-4e0d-9105-bacbe7836a3c
ca.log.AuditErr(err)
return emptyCert, err
}
if badSignatureAlgorithms[csr.SignatureAlgorithm] {
err = fmt.Errorf("Invalid signature algorithm in CSR")
// AUDIT[ Certificate Requests ] 11917fa4-10ef-4e0d-9105-bacbe7836a3c
ca.log.AuditErr(err)
return emptyCert, err
}
// Pull hostnames from CSR
// Authorization is checked by the RA
commonName := ""
hostNames := make([]string, len(csr.DNSNames))
copy(hostNames, csr.DNSNames)
if len(csr.Subject.CommonName) > 0 {
commonName = csr.Subject.CommonName
hostNames = append(hostNames, csr.Subject.CommonName)
} else if len(hostNames) > 0 {
commonName = hostNames[0]
} else {
err = fmt.Errorf("Cannot issue a certificate without a hostname.")
// AUDIT[ Certificate Requests ] 11917fa4-10ef-4e0d-9105-bacbe7836a3c
ca.log.AuditErr(err)
return emptyCert, err
}
// Collapse any duplicate names. Note that this operation may re-order the names
hostNames = core.UniqueNames(hostNames)
if ca.MaxNames > 0 && len(hostNames) > ca.MaxNames {
err = fmt.Errorf("Certificate request has %d > %d names", len(hostNames), ca.MaxNames)
ca.log.WarningErr(err)
return emptyCert, err
}
// Verify that names are allowed by policy
identifier := core.AcmeIdentifier{Type: core.IdentifierDNS, Value: commonName}
if err = ca.PA.WillingToIssue(identifier); err != nil {
err = fmt.Errorf("Policy forbids issuing for name %s", commonName)
// AUDIT[ Certificate Requests ] 11917fa4-10ef-4e0d-9105-bacbe7836a3c
ca.log.AuditErr(err)
return emptyCert, err
}
for _, name := range hostNames {
identifier = core.AcmeIdentifier{Type: core.IdentifierDNS, Value: name}
if err = ca.PA.WillingToIssue(identifier); err != nil {
err = fmt.Errorf("Policy forbids issuing for name %s", name)
// AUDIT[ Certificate Requests ] 11917fa4-10ef-4e0d-9105-bacbe7836a3c
ca.log.AuditErr(err)
return emptyCert, err
}
}
notAfter := ca.Clk.Now().Add(ca.ValidityPeriod)
if ca.NotAfter.Before(notAfter) {
// AUDIT[ Certificate Requests ] 11917fa4-10ef-4e0d-9105-bacbe7836a3c
err = errors.New("Cannot issue a certificate that expires after the intermediate certificate.")
ca.log.AuditErr(err)
return emptyCert, err
}
// Note: We do not current enforce that certificate lifetimes match
// authorization lifetimes, because it was breaking integration tests.
if earliestExpiry.Before(notAfter) {
message := fmt.Sprintf("Issuing a certificate that expires after the shortest underlying authorization. [%v] [%v]", earliestExpiry, notAfter)
ca.log.Notice(message)
}
// Convert the CSR to PEM
csrPEM := string(pem.EncodeToMemory(&pem.Block{
Type: "CERTIFICATE REQUEST",
Bytes: csr.Raw,
}))
// Get the next serial number
tx, err := ca.DB.Begin()
if err != nil {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.AuditErr(err)
return emptyCert, err
}
serialDec, err := ca.DB.IncrementAndGetSerial(tx)
if err != nil {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.Audit(fmt.Sprintf("Serial increment failed, rolling back: err=[%v]", err))
tx.Rollback()
return emptyCert, err
}
serialHex := fmt.Sprintf("%02X%014X", ca.Prefix, serialDec)
// Send the cert off for signing
req := signer.SignRequest{
Request: csrPEM,
Profile: ca.profile,
Hosts: hostNames,
Subject: &signer.Subject{
CN: commonName,
},
SerialSeq: serialHex,
}
certPEM, err := ca.Signer.Sign(req)
if err != nil {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.Audit(fmt.Sprintf("Signer failed, rolling back: serial=[%s] err=[%v]", serialHex, err))
tx.Rollback()
return emptyCert, err
}
if len(certPEM) == 0 {
err = fmt.Errorf("No certificate returned by server")
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.Audit(fmt.Sprintf("PEM empty from Signer, rolling back: serial=[%s] err=[%v]", serialHex, err))
tx.Rollback()
return emptyCert, err
}
block, _ := pem.Decode(certPEM)
if block == nil || block.Type != "CERTIFICATE" {
err = fmt.Errorf("Invalid certificate value returned")
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.Audit(fmt.Sprintf("PEM decode error, aborting and rolling back issuance: pem=[%s] err=[%v]", certPEM, err))
tx.Rollback()
return emptyCert, err
}
certDER := block.Bytes
cert := core.Certificate{
DER: certDER,
}
// This is one last check for uncaught errors
if err != nil {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.Audit(fmt.Sprintf("Uncaught error, aborting and rolling back issuance: pem=[%s] err=[%v]", certPEM, err))
tx.Rollback()
return emptyCert, err
}
// Store the cert with the certificate authority, if provided
_, err = ca.SA.AddCertificate(certDER, regID)
if err != nil {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.Audit(fmt.Sprintf("Failed RPC to store at SA, orphaning certificate: pem=[%s] err=[%v]", certPEM, err))
tx.Rollback()
return emptyCert, err
}
if err = tx.Commit(); err != nil {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
ca.log.Audit(fmt.Sprintf("Failed to commit, orphaning certificate: pem=[%s] err=[%v]", certPEM, err))
return emptyCert, err
}
// Attempt to generate the OCSP Response now. If this raises an error, it is
// logged but is not returned to the caller, as an error at this point does
// not constitute an issuance failure.
certObj, err := x509.ParseCertificate(certDER)
if err != nil {
ca.log.Warning(fmt.Sprintf("Post-Issuance OCSP failed parsing Certificate: %s", err))
return cert, nil
}
serial := core.SerialToString(certObj.SerialNumber)
signRequest := ocsp.SignRequest{
Certificate: certObj,
Status: string(core.OCSPStatusGood),
}
ocspResponse, err := ca.OCSPSigner.Sign(signRequest)
if err != nil {
ca.log.Warning(fmt.Sprintf("Post-Issuance OCSP failed signing: %s", err))
return cert, nil
}
err = ca.SA.UpdateOCSP(serial, ocspResponse)
if err != nil {
ca.log.Warning(fmt.Sprintf("Post-Issuance OCSP failed storing: %s", err))
return cert, nil
}
// Do not return an err at this point; caller must know that the Certificate
// was issued. (Also, it should be impossible for err to be non-nil here)
return cert, nil
}