437 lines
13 KiB
Go
437 lines
13 KiB
Go
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// Package signer implements certificate signature functionality for CFSSL.
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package signer
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import (
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"crypto"
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rsa"
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"crypto/sha1"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/asn1"
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"errors"
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"math/big"
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"net/http"
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"strings"
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"time"
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"github.com/cloudflare/cfssl/certdb"
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"github.com/cloudflare/cfssl/config"
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"github.com/cloudflare/cfssl/csr"
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cferr "github.com/cloudflare/cfssl/errors"
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"github.com/cloudflare/cfssl/info"
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)
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// Subject contains the information that should be used to override the
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// subject information when signing a certificate.
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type Subject struct {
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CN string
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Names []csr.Name `json:"names"`
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SerialNumber string
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}
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// Extension represents a raw extension to be included in the certificate. The
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// "value" field must be hex encoded.
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type Extension struct {
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ID config.OID `json:"id"`
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Critical bool `json:"critical"`
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Value string `json:"value"`
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}
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// SignRequest stores a signature request, which contains the hostname,
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// the CSR, optional subject information, and the signature profile.
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//
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// Extensions provided in the signRequest are copied into the certificate, as
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// long as they are in the ExtensionWhitelist for the signer's policy.
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// Extensions requested in the CSR are ignored, except for those processed by
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// ParseCertificateRequest (mainly subjectAltName).
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type SignRequest struct {
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Hosts []string `json:"hosts"`
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Request string `json:"certificate_request"`
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Subject *Subject `json:"subject,omitempty"`
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Profile string `json:"profile"`
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CRLOverride string `json:"crl_override"`
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Label string `json:"label"`
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Serial *big.Int `json:"serial,omitempty"`
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Extensions []Extension `json:"extensions,omitempty"`
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// If provided, NotBefore will be used without modification (except
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// for canonicalization) as the value of the notBefore field of the
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// certificate. In particular no backdating adjustment will be made
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// when NotBefore is provided.
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NotBefore time.Time
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// If provided, NotAfter will be used without modification (except
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// for canonicalization) as the value of the notAfter field of the
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// certificate.
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NotAfter time.Time
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// If ReturnPrecert is true a certificate with the CT poison extension
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// will be returned from the Signer instead of attempting to retrieve
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// SCTs and populate the tbsCert with them itself. This precert can then
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// be passed to SignFromPrecert with the SCTs in order to create a
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// valid certificate.
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ReturnPrecert bool
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}
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// appendIf appends to a if s is not an empty string.
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func appendIf(s string, a *[]string) {
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if s != "" {
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*a = append(*a, s)
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}
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}
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// Name returns the PKIX name for the subject.
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func (s *Subject) Name() pkix.Name {
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var name pkix.Name
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name.CommonName = s.CN
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for _, n := range s.Names {
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appendIf(n.C, &name.Country)
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appendIf(n.ST, &name.Province)
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appendIf(n.L, &name.Locality)
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appendIf(n.O, &name.Organization)
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appendIf(n.OU, &name.OrganizationalUnit)
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}
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name.SerialNumber = s.SerialNumber
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return name
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}
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// SplitHosts takes a comma-spearated list of hosts and returns a slice
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// with the hosts split
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func SplitHosts(hostList string) []string {
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if hostList == "" {
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return nil
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}
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return strings.Split(hostList, ",")
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}
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// A Signer contains a CA's certificate and private key for signing
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// certificates, a Signing policy to refer to and a SignatureAlgorithm.
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type Signer interface {
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Info(info.Req) (*info.Resp, error)
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Policy() *config.Signing
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SetDBAccessor(certdb.Accessor)
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GetDBAccessor() certdb.Accessor
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SetPolicy(*config.Signing)
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SigAlgo() x509.SignatureAlgorithm
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Sign(req SignRequest) (cert []byte, err error)
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SetReqModifier(func(*http.Request, []byte))
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}
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// Profile gets the specific profile from the signer
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func Profile(s Signer, profile string) (*config.SigningProfile, error) {
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var p *config.SigningProfile
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policy := s.Policy()
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if policy != nil && policy.Profiles != nil && profile != "" {
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p = policy.Profiles[profile]
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}
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if p == nil && policy != nil {
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p = policy.Default
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}
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if p == nil {
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return nil, cferr.Wrap(cferr.APIClientError, cferr.ClientHTTPError, errors.New("profile must not be nil"))
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}
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return p, nil
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}
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// DefaultSigAlgo returns an appropriate X.509 signature algorithm given
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// the CA's private key.
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func DefaultSigAlgo(priv crypto.Signer) x509.SignatureAlgorithm {
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pub := priv.Public()
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switch pub := pub.(type) {
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case *rsa.PublicKey:
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keySize := pub.N.BitLen()
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switch {
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case keySize >= 4096:
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return x509.SHA512WithRSA
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case keySize >= 3072:
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return x509.SHA384WithRSA
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case keySize >= 2048:
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return x509.SHA256WithRSA
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default:
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return x509.SHA1WithRSA
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}
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case *ecdsa.PublicKey:
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switch pub.Curve {
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case elliptic.P256():
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return x509.ECDSAWithSHA256
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case elliptic.P384():
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return x509.ECDSAWithSHA384
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case elliptic.P521():
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return x509.ECDSAWithSHA512
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default:
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return x509.ECDSAWithSHA1
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}
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default:
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return x509.UnknownSignatureAlgorithm
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}
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}
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// ParseCertificateRequest takes an incoming certificate request and
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// builds a certificate template from it.
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func ParseCertificateRequest(s Signer, csrBytes []byte) (template *x509.Certificate, err error) {
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csrv, err := x509.ParseCertificateRequest(csrBytes)
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if err != nil {
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err = cferr.Wrap(cferr.CSRError, cferr.ParseFailed, err)
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return
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}
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err = csrv.CheckSignature()
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if err != nil {
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err = cferr.Wrap(cferr.CSRError, cferr.KeyMismatch, err)
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return
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}
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template = &x509.Certificate{
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Subject: csrv.Subject,
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PublicKeyAlgorithm: csrv.PublicKeyAlgorithm,
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PublicKey: csrv.PublicKey,
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SignatureAlgorithm: s.SigAlgo(),
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DNSNames: csrv.DNSNames,
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IPAddresses: csrv.IPAddresses,
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EmailAddresses: csrv.EmailAddresses,
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}
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for _, val := range csrv.Extensions {
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// Check the CSR for the X.509 BasicConstraints (RFC 5280, 4.2.1.9)
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// extension and append to template if necessary
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if val.Id.Equal(asn1.ObjectIdentifier{2, 5, 29, 19}) {
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var constraints csr.BasicConstraints
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var rest []byte
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if rest, err = asn1.Unmarshal(val.Value, &constraints); err != nil {
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return nil, cferr.Wrap(cferr.CSRError, cferr.ParseFailed, err)
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} else if len(rest) != 0 {
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return nil, cferr.Wrap(cferr.CSRError, cferr.ParseFailed, errors.New("x509: trailing data after X.509 BasicConstraints"))
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}
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template.BasicConstraintsValid = true
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template.IsCA = constraints.IsCA
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template.MaxPathLen = constraints.MaxPathLen
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template.MaxPathLenZero = template.MaxPathLen == 0
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}
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}
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return
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}
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type subjectPublicKeyInfo struct {
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Algorithm pkix.AlgorithmIdentifier
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SubjectPublicKey asn1.BitString
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}
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// ComputeSKI derives an SKI from the certificate's public key in a
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// standard manner. This is done by computing the SHA-1 digest of the
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// SubjectPublicKeyInfo component of the certificate.
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func ComputeSKI(template *x509.Certificate) ([]byte, error) {
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pub := template.PublicKey
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encodedPub, err := x509.MarshalPKIXPublicKey(pub)
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if err != nil {
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return nil, err
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}
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var subPKI subjectPublicKeyInfo
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_, err = asn1.Unmarshal(encodedPub, &subPKI)
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if err != nil {
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return nil, err
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}
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pubHash := sha1.Sum(subPKI.SubjectPublicKey.Bytes)
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return pubHash[:], nil
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}
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// FillTemplate is a utility function that tries to load as much of
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// the certificate template as possible from the profiles and current
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// template. It fills in the key uses, expiration, revocation URLs
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// and SKI.
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func FillTemplate(template *x509.Certificate, defaultProfile, profile *config.SigningProfile, notBefore time.Time, notAfter time.Time) error {
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ski, err := ComputeSKI(template)
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if err != nil {
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return err
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}
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var (
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eku []x509.ExtKeyUsage
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ku x509.KeyUsage
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backdate time.Duration
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expiry time.Duration
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crlURL, ocspURL string
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issuerURL = profile.IssuerURL
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)
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// The third value returned from Usages is a list of unknown key usages.
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// This should be used when validating the profile at load, and isn't used
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// here.
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ku, eku, _ = profile.Usages()
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if profile.IssuerURL == nil {
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issuerURL = defaultProfile.IssuerURL
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}
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if ku == 0 && len(eku) == 0 {
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return cferr.New(cferr.PolicyError, cferr.NoKeyUsages)
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}
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if expiry = profile.Expiry; expiry == 0 {
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expiry = defaultProfile.Expiry
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}
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if crlURL = profile.CRL; crlURL == "" {
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crlURL = defaultProfile.CRL
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}
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if ocspURL = profile.OCSP; ocspURL == "" {
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ocspURL = defaultProfile.OCSP
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}
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if notBefore.IsZero() {
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if !profile.NotBefore.IsZero() {
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notBefore = profile.NotBefore
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} else {
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if backdate = profile.Backdate; backdate == 0 {
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backdate = -5 * time.Minute
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} else {
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backdate = -1 * profile.Backdate
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}
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notBefore = time.Now().Round(time.Minute).Add(backdate)
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}
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}
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notBefore = notBefore.UTC()
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if notAfter.IsZero() {
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if !profile.NotAfter.IsZero() {
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notAfter = profile.NotAfter
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} else {
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notAfter = notBefore.Add(expiry)
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}
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}
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notAfter = notAfter.UTC()
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template.NotBefore = notBefore
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template.NotAfter = notAfter
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template.KeyUsage = ku
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template.ExtKeyUsage = eku
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template.BasicConstraintsValid = true
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template.IsCA = profile.CAConstraint.IsCA
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if template.IsCA {
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template.MaxPathLen = profile.CAConstraint.MaxPathLen
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if template.MaxPathLen == 0 {
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template.MaxPathLenZero = profile.CAConstraint.MaxPathLenZero
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}
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template.DNSNames = nil
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template.EmailAddresses = nil
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}
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template.SubjectKeyId = ski
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if ocspURL != "" {
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template.OCSPServer = []string{ocspURL}
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}
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if crlURL != "" {
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template.CRLDistributionPoints = []string{crlURL}
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}
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if len(issuerURL) != 0 {
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template.IssuingCertificateURL = issuerURL
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}
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if len(profile.Policies) != 0 {
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err = addPolicies(template, profile.Policies)
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if err != nil {
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return cferr.Wrap(cferr.PolicyError, cferr.InvalidPolicy, err)
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}
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}
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if profile.OCSPNoCheck {
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ocspNoCheckExtension := pkix.Extension{
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Id: asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 48, 1, 5},
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Critical: false,
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Value: []byte{0x05, 0x00},
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}
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template.ExtraExtensions = append(template.ExtraExtensions, ocspNoCheckExtension)
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}
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return nil
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}
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type policyInformation struct {
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PolicyIdentifier asn1.ObjectIdentifier
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Qualifiers []interface{} `asn1:"tag:optional,omitempty"`
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}
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type cpsPolicyQualifier struct {
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PolicyQualifierID asn1.ObjectIdentifier
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Qualifier string `asn1:"tag:optional,ia5"`
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}
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type userNotice struct {
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ExplicitText string `asn1:"tag:optional,utf8"`
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}
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type userNoticePolicyQualifier struct {
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PolicyQualifierID asn1.ObjectIdentifier
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Qualifier userNotice
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}
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var (
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// Per https://tools.ietf.org/html/rfc3280.html#page-106, this represents:
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// iso(1) identified-organization(3) dod(6) internet(1) security(5)
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// mechanisms(5) pkix(7) id-qt(2) id-qt-cps(1)
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iDQTCertificationPracticeStatement = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 2, 1}
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// iso(1) identified-organization(3) dod(6) internet(1) security(5)
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// mechanisms(5) pkix(7) id-qt(2) id-qt-unotice(2)
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|
|
iDQTUserNotice = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 2, 2}
|
||
|
|
|
||
|
|
// CTPoisonOID is the object ID of the critical poison extension for precertificates
|
||
|
|
// https://tools.ietf.org/html/rfc6962#page-9
|
||
|
|
CTPoisonOID = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 11129, 2, 4, 3}
|
||
|
|
|
||
|
|
// SCTListOID is the object ID for the Signed Certificate Timestamp certificate extension
|
||
|
|
// https://tools.ietf.org/html/rfc6962#page-14
|
||
|
|
SCTListOID = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 11129, 2, 4, 2}
|
||
|
|
)
|
||
|
|
|
||
|
|
// addPolicies adds Certificate Policies and optional Policy Qualifiers to a
|
||
|
|
// certificate, based on the input config. Go's x509 library allows setting
|
||
|
|
// Certificate Policies easily, but does not support nested Policy Qualifiers
|
||
|
|
// under those policies. So we need to construct the ASN.1 structure ourselves.
|
||
|
|
func addPolicies(template *x509.Certificate, policies []config.CertificatePolicy) error {
|
||
|
|
asn1PolicyList := []policyInformation{}
|
||
|
|
|
||
|
|
for _, policy := range policies {
|
||
|
|
pi := policyInformation{
|
||
|
|
// The PolicyIdentifier is an OID assigned to a given issuer.
|
||
|
|
PolicyIdentifier: asn1.ObjectIdentifier(policy.ID),
|
||
|
|
}
|
||
|
|
for _, qualifier := range policy.Qualifiers {
|
||
|
|
switch qualifier.Type {
|
||
|
|
case "id-qt-unotice":
|
||
|
|
pi.Qualifiers = append(pi.Qualifiers,
|
||
|
|
userNoticePolicyQualifier{
|
||
|
|
PolicyQualifierID: iDQTUserNotice,
|
||
|
|
Qualifier: userNotice{
|
||
|
|
ExplicitText: qualifier.Value,
|
||
|
|
},
|
||
|
|
})
|
||
|
|
case "id-qt-cps":
|
||
|
|
pi.Qualifiers = append(pi.Qualifiers,
|
||
|
|
cpsPolicyQualifier{
|
||
|
|
PolicyQualifierID: iDQTCertificationPracticeStatement,
|
||
|
|
Qualifier: qualifier.Value,
|
||
|
|
})
|
||
|
|
default:
|
||
|
|
return errors.New("Invalid qualifier type in Policies " + qualifier.Type)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
asn1PolicyList = append(asn1PolicyList, pi)
|
||
|
|
}
|
||
|
|
|
||
|
|
asn1Bytes, err := asn1.Marshal(asn1PolicyList)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
|
||
|
|
template.ExtraExtensions = append(template.ExtraExtensions, pkix.Extension{
|
||
|
|
Id: asn1.ObjectIdentifier{2, 5, 29, 32},
|
||
|
|
Critical: false,
|
||
|
|
Value: asn1Bytes,
|
||
|
|
})
|
||
|
|
return nil
|
||
|
|
}
|