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certificate_flow.go
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certificate_flow.go
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package cautils
import (
"crypto"
"crypto/rand"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"net"
"os"
"strings"
"time"
"github.com/pkg/errors"
"github.com/smallstep/certificates/api"
"github.com/smallstep/certificates/authority/provisioner"
"github.com/smallstep/certificates/ca"
"github.com/smallstep/cli/crypto/keys"
"github.com/smallstep/cli/crypto/pemutil"
"github.com/smallstep/cli/crypto/pki"
"github.com/smallstep/cli/crypto/x509util"
"github.com/smallstep/cli/errs"
"github.com/smallstep/cli/token"
"github.com/smallstep/cli/ui"
"github.com/smallstep/cli/utils"
"github.com/urfave/cli"
)
// CertificateFlow manages the flow to retrieve a new certificate.
type CertificateFlow struct {
offlineCA *OfflineCA
offline bool
}
// sharedContext is used to share information between commands.
var sharedContext = struct {
DisableCustomSANs bool
}{}
// NewCertificateFlow initializes a cli flow to get a new certificate.
func NewCertificateFlow(ctx *cli.Context) (*CertificateFlow, error) {
var err error
var offlineClient *OfflineCA
offline := ctx.Bool("offline")
if offline {
caConfig := ctx.String("ca-config")
if caConfig == "" {
return nil, errs.InvalidFlagValue(ctx, "ca-config", "", "")
}
offlineClient, err = NewOfflineCA(caConfig)
if err != nil {
return nil, err
}
}
return &CertificateFlow{
offlineCA: offlineClient,
offline: offline,
}, nil
}
// GetClient returns the client used to send requests to the CA.
func (f *CertificateFlow) GetClient(ctx *cli.Context, subject, tok string) (CaClient, error) {
if f.offline {
return f.offlineCA, nil
}
// Create online client
root := ctx.String("root")
caURL := ctx.String("ca-url")
jwt, err := token.ParseInsecure(tok)
if err != nil {
return nil, errors.Wrap(err, "error parsing flag '--token'")
}
// Prepare client for bootstrap or provisioning tokens
var options []ca.ClientOption
if len(jwt.Payload.SHA) > 0 && len(jwt.Payload.Audience) > 0 && strings.HasPrefix(strings.ToLower(jwt.Payload.Audience[0]), "http") {
if len(caURL) == 0 {
caURL = jwt.Payload.Audience[0]
}
options = append(options, ca.WithRootSHA256(jwt.Payload.SHA))
} else {
if len(caURL) == 0 {
return nil, errs.RequiredFlag(ctx, "ca-url")
}
if len(root) == 0 {
root = pki.GetRootCAPath()
if _, err := os.Stat(root); err != nil {
return nil, errs.RequiredFlag(ctx, "root")
}
}
options = append(options, ca.WithRootFile(root))
}
ui.PrintSelected("CA", caURL)
return ca.NewClient(caURL, options...)
}
// GenerateToken generates a token for immediate use (therefore only default
// validity values will be used). The token is generated either with the offline
// token flow or the online mode.
func (f *CertificateFlow) GenerateToken(ctx *cli.Context, subject string, sans []string) (string, error) {
if f.offline {
return f.offlineCA.GenerateToken(ctx, SignType, subject, sans, time.Time{}, time.Time{}, provisioner.TimeDuration{}, provisioner.TimeDuration{})
}
// Use online CA to get the provisioners and generate the token
caURL := ctx.String("ca-url")
if len(caURL) == 0 {
return "", errs.RequiredUnlessFlag(ctx, "ca-url", "token")
}
root := ctx.String("root")
if len(root) == 0 {
root = pki.GetRootCAPath()
if _, err := os.Stat(root); err != nil {
return "", errs.RequiredUnlessFlag(ctx, "root", "token")
}
}
var err error
if subject == "" {
subject, err = ui.Prompt("What DNS names or IP addresses would you like to use? (e.g. internal.smallstep.com)", ui.WithValidateNotEmpty())
if err != nil {
return "", err
}
}
return NewTokenFlow(ctx, SignType, subject, sans, caURL, root, time.Time{}, time.Time{}, provisioner.TimeDuration{}, provisioner.TimeDuration{})
}
// GenerateSSHToken generates a token used to authorize the sign of an SSH
// certificate.
func (f *CertificateFlow) GenerateSSHToken(ctx *cli.Context, subject, certType string, principals []string, validAfter, validBefore provisioner.TimeDuration) (string, error) {
var typ int
switch certType {
case provisioner.SSHUserCert:
typ = SSHUserSignType
case provisioner.SSHHostCert:
typ = SSHHostSignType
default:
return "", errors.Errorf("unsupported cert type %s", certType)
}
if f.offline {
return f.offlineCA.GenerateToken(ctx, typ, subject, principals, time.Time{}, time.Time{}, validAfter, validBefore)
}
// Use online CA to get the provisioners and generate the token
caURL := ctx.String("ca-url")
if len(caURL) == 0 {
return "", errs.RequiredUnlessFlag(ctx, "ca-url", "token")
}
root := ctx.String("root")
if len(root) == 0 {
root = pki.GetRootCAPath()
if _, err := os.Stat(root); err != nil {
return "", errs.RequiredUnlessFlag(ctx, "root", "token")
}
}
var err error
if subject == "" {
subject, err = ui.Prompt("What DNS names or IP addresses would you like to use? (e.g. internal.smallstep.com)", ui.WithValidateNotEmpty())
if err != nil {
return "", err
}
}
return NewTokenFlow(ctx, typ, subject, principals, caURL, root, time.Time{}, time.Time{}, validAfter, validBefore)
}
// Sign signs the CSR using the online or the offline certificate authority.
func (f *CertificateFlow) Sign(ctx *cli.Context, token string, csr api.CertificateRequest, crtFile string) error {
client, err := f.GetClient(ctx, csr.Subject.CommonName, token)
if err != nil {
return err
}
// parse times or durations
notBefore, notAfter, err := parseTimeDuration(ctx)
if err != nil {
return err
}
req := &api.SignRequest{
CsrPEM: csr,
OTT: token,
NotBefore: notBefore,
NotAfter: notAfter,
}
resp, err := client.Sign(req)
if err != nil {
return err
}
serverBlock, err := pemutil.Serialize(resp.ServerPEM.Certificate)
if err != nil {
return err
}
caBlock, err := pemutil.Serialize(resp.CaPEM.Certificate)
if err != nil {
return err
}
data := append(pem.EncodeToMemory(serverBlock), pem.EncodeToMemory(caBlock)...)
return utils.WriteFile(crtFile, data, 0600)
}
// CreateSignRequest is a helper function that given an x509 OTT returns a
// simple but secure sign request as well as the private key used.
func (f *CertificateFlow) CreateSignRequest(ctx *cli.Context, tok, subject string, sans []string) (*api.SignRequest, crypto.PrivateKey, error) {
jwt, err := token.ParseInsecure(tok)
if err != nil {
return nil, nil, err
}
kty, crv, size, err := utils.GetKeyDetailsFromCLI(ctx, false, "kty", "curve", "size")
if err != nil {
return nil, nil, err
}
pk, err := keys.GenerateKey(kty, crv, size)
if err != nil {
return nil, nil, err
}
dnsNames, ips, emails := splitSANs(sans, jwt.Payload.SANs)
switch jwt.Payload.Type() {
case token.AWS:
doc := jwt.Payload.Amazon.InstanceIdentityDocument
if len(ips) == 0 && len(dnsNames) == 0 {
defaultSANs := []string{
doc.PrivateIP,
fmt.Sprintf("ip-%s.%s.compute.internal", strings.Replace(doc.PrivateIP, ".", "-", -1), doc.Region),
}
if !sharedContext.DisableCustomSANs {
defaultSANs = append(defaultSANs, subject)
}
dnsNames, ips, emails = splitSANs(defaultSANs)
}
case token.GCP:
ce := jwt.Payload.Google.ComputeEngine
if len(ips) == 0 && len(dnsNames) == 0 {
defaultSANs := []string{
fmt.Sprintf("%s.c.%s.internal", ce.InstanceName, ce.ProjectID),
fmt.Sprintf("%s.%s.c.%s.internal", ce.InstanceName, ce.Zone, ce.ProjectID),
}
if !sharedContext.DisableCustomSANs {
defaultSANs = append(defaultSANs, subject)
}
dnsNames, ips, emails = splitSANs(defaultSANs)
}
case token.Azure:
if len(ips) == 0 && len(dnsNames) == 0 {
defaultSANs := []string{
jwt.Payload.Azure.VirtualMachine,
}
if !sharedContext.DisableCustomSANs {
defaultSANs = append(defaultSANs, subject)
}
dnsNames, ips, emails = splitSANs(defaultSANs)
}
case token.OIDC:
if jwt.Payload.Email != "" {
emails = append(emails, jwt.Payload.Email)
}
subject = jwt.Payload.Subject
default: // Use common name in the token
subject = jwt.Payload.Subject
}
template := &x509.CertificateRequest{
Subject: pkix.Name{
CommonName: subject,
},
DNSNames: dnsNames,
IPAddresses: ips,
EmailAddresses: emails,
}
csr, err := x509.CreateCertificateRequest(rand.Reader, template, pk)
if err != nil {
return nil, nil, errors.Wrap(err, "error creating certificate request")
}
cr, err := x509.ParseCertificateRequest(csr)
if err != nil {
return nil, nil, errors.Wrap(err, "error parsing certificate request")
}
if err := cr.CheckSignature(); err != nil {
return nil, nil, errors.Wrap(err, "error signing certificate request")
}
return &api.SignRequest{
CsrPEM: api.CertificateRequest{CertificateRequest: cr},
OTT: tok,
}, pk, nil
}
// splitSANs unifies the SAN collections passed as arguments and returns a list
// of DNS names, a list of IP addresses, and a list of emails.
func splitSANs(args ...[]string) (dnsNames []string, ipAddresses []net.IP, email []string) {
m := make(map[string]bool)
var unique []string
for _, sans := range args {
for _, san := range sans {
if ok := m[san]; !ok {
m[san] = true
unique = append(unique, san)
}
}
}
return x509util.SplitSANs(unique)
}
// parseTimeDuration parses the not-before and not-after flags as a timeDuration
func parseTimeDuration(ctx *cli.Context) (notBefore api.TimeDuration, notAfter api.TimeDuration, err error) {
var zero api.TimeDuration
notBefore, err = api.ParseTimeDuration(ctx.String("not-before"))
if err != nil {
return zero, zero, errs.InvalidFlagValue(ctx, "not-before", ctx.String("not-before"), "")
}
notAfter, err = api.ParseTimeDuration(ctx.String("not-after"))
if err != nil {
return zero, zero, errs.InvalidFlagValue(ctx, "not-after", ctx.String("not-after"), "")
}
return
}