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// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package caddytls
import (
"bytes"
"context"
"crypto/x509"
"encoding/pem"
"time"
"github.com/caddyserver/certmagic"
"github.com/smallstep/certificates/authority/provisioner"
"go.uber.org/zap"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
"github.com/caddyserver/caddy/v2/modules/caddypki"
)
func init() {
caddy.RegisterModule(InternalIssuer{})
}
// InternalIssuer is a certificate issuer that generates
// certificates internally using a locally-configured
// CA which can be customized using the `pki` app.
type InternalIssuer struct {
// The ID of the CA to use for signing. The default
// CA ID is "local". The CA can be configured with the
// `pki` app.
CA string `json:"ca,omitempty"`
// The validity period of certificates.
Lifetime caddy.Duration `json:"lifetime,omitempty"`
// If true, the root will be the issuer instead of
// the intermediate. This is NOT recommended and should
// only be used when devices/clients do not properly
// validate certificate chains.
SignWithRoot bool `json:"sign_with_root,omitempty"`
ca *caddypki.CA
logger *zap.Logger
}
// CaddyModule returns the Caddy module information.
func (InternalIssuer) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "tls.issuance.internal",
New: func() caddy.Module { return new(InternalIssuer) },
}
}
// Provision sets up the issuer.
func (iss *InternalIssuer) Provision(ctx caddy.Context) error {
iss.logger = ctx.Logger()
// set some defaults
if iss.CA == "" {
iss.CA = caddypki.DefaultCAID
}
// get a reference to the configured CA
appModule, err := ctx.App("pki")
if err != nil {
return err
}
pkiApp := appModule.(*caddypki.PKI)
ca, err := pkiApp.GetCA(ctx, iss.CA)
if err != nil {
return err
}
iss.ca = ca
// set any other default values
if iss.Lifetime == 0 {
iss.Lifetime = caddy.Duration(defaultInternalCertLifetime)
}
return nil
}
// IssuerKey returns the unique issuer key for the
// configured CA endpoint.
func (iss InternalIssuer) IssuerKey() string {
return iss.ca.ID
}
// Issue issues a certificate to satisfy the CSR.
func (iss InternalIssuer) Issue(ctx context.Context, csr *x509.CertificateRequest) (*certmagic.IssuedCertificate, error) {
// prepare the signing authority
authCfg := caddypki.AuthorityConfig{
SignWithRoot: iss.SignWithRoot,
}
auth, err := iss.ca.NewAuthority(authCfg)
if err != nil {
return nil, err
}
// get the cert (public key) that will be used for signing
var issuerCert *x509.Certificate
if iss.SignWithRoot {
issuerCert = iss.ca.RootCertificate()
} else {
issuerCert = iss.ca.IntermediateCertificate()
}
// ensure issued certificate does not expire later than its issuer
lifetime := time.Duration(iss.Lifetime)
if time.Now().Add(lifetime).After(issuerCert.NotAfter) {
lifetime = time.Until(issuerCert.NotAfter)
iss.logger.Warn("cert lifetime would exceed issuer NotAfter, clamping lifetime",
zap.Duration("orig_lifetime", time.Duration(iss.Lifetime)),
zap.Duration("lifetime", lifetime),
zap.Time("not_after", issuerCert.NotAfter),
)
}
certChain, err := auth.Sign(csr, provisioner.SignOptions{}, customCertLifetime(caddy.Duration(lifetime)))
if err != nil {
return nil, err
}
var buf bytes.Buffer
for _, cert := range certChain {
err := pem.Encode(&buf, &pem.Block{Type: "CERTIFICATE", Bytes: cert.Raw})
if err != nil {
return nil, err
}
}
return &certmagic.IssuedCertificate{
Certificate: buf.Bytes(),
}, nil
}
// UnmarshalCaddyfile deserializes Caddyfile tokens into iss.
//
// ... internal {
// ca <name>
// lifetime <duration>
// sign_with_root
// }
func (iss *InternalIssuer) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
d.Next() // consume issuer name
for d.NextBlock(0) {
switch d.Val() {
case "ca":
if !d.AllArgs(&iss.CA) {
return d.ArgErr()
}
case "lifetime":
if !d.NextArg() {
return d.ArgErr()
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return err
}
iss.Lifetime = caddy.Duration(dur)
case "sign_with_root":
if d.NextArg() {
return d.ArgErr()
}
iss.SignWithRoot = true
}
}
return nil
}
// customCertLifetime allows us to customize certificates that are issued
// by Smallstep libs, particularly the NotBefore & NotAfter dates.
type customCertLifetime time.Duration
func (d customCertLifetime) Modify(cert *x509.Certificate, _ provisioner.SignOptions) error {
cert.NotBefore = time.Now()
cert.NotAfter = cert.NotBefore.Add(time.Duration(d))
return nil
}
const defaultInternalCertLifetime = 12 * time.Hour
// Interface guards
var (
_ caddy.Provisioner = (*InternalIssuer)(nil)
_ certmagic.Issuer = (*InternalIssuer)(nil)
_ provisioner.CertificateModifier = (*customCertLifetime)(nil)
)
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