acme_server: Configurable default lifetime for issued certificates (#5232)

* acme_server: add certificate lifetime configuration option

Signed-off-by: Kyle McCullough <kylemcc@gmail.com>

* pki: allow intermediate cert lifetime to be configured

Signed-off-by: Kyle McCullough <kylemcc@gmail.com>

Signed-off-by: Kyle McCullough <kylemcc@gmail.com>

4 files changed, 43 insertions, 4 deletions

diff --git a/modules/caddypki/acmeserver/acmeserver.go b/modules/caddypki/acmeserver/acmeserver.go
index 921d0b8..6ecdfdc 100644
--- a/modules/caddypki/acmeserver/acmeserver.go
+++ b/modules/caddypki/acmeserver/acmeserver.go
@@ -48,6 +48,9 @@ type Handler struct {
 	// the default ID is "local".
 	CA string `json:"ca,omitempty"`
 
+	// The lifetime for issued certificates
+	Lifetime caddy.Duration `json:"lifetime,omitempty"`
+
 	// The hostname or IP address by which ACME clients
 	// will access the server. This is used to populate
 	// the ACME directory endpoint. If not set, the Host
@@ -95,6 +98,9 @@ func (ash *Handler) Provision(ctx caddy.Context) error {
 	if ash.PathPrefix == "" {
 		ash.PathPrefix = defaultPathPrefix
 	}
+	if ash.Lifetime == 0 {
+		ash.Lifetime = caddy.Duration(12 * time.Hour)
+	}
 
 	// get a reference to the configured CA
 	appModule, err := ctx.App("pki")
@@ -107,6 +113,12 @@ func (ash *Handler) Provision(ctx caddy.Context) error {
 		return err
 	}
 
+	// make sure leaf cert lifetime is less than the intermediate cert lifetime. this check only
+	// applies for caddy-managed intermediate certificates
+	if ca.Intermediate == nil && ash.Lifetime >= ca.IntermediateLifetime {
+		return fmt.Errorf("certificate lifetime (%s) should be less than intermediate certificate lifetime (%s)", time.Duration(ash.Lifetime), time.Duration(ca.IntermediateLifetime))
+	}
+
 	database, err := ash.openDatabase()
 	if err != nil {
 		return err
@@ -122,7 +134,7 @@ func (ash *Handler) Provision(ctx caddy.Context) error {
 					Claims: &provisioner.Claims{
 						MinTLSDur:     &provisioner.Duration{Duration: 5 * time.Minute},
 						MaxTLSDur:     &provisioner.Duration{Duration: 24 * time.Hour * 365},
-						DefaultTLSDur: &provisioner.Duration{Duration: 12 * time.Hour},
+						DefaultTLSDur: &provisioner.Duration{Duration: time.Duration(ash.Lifetime)},
 					},
 				},
 			},
diff --git a/modules/caddypki/acmeserver/caddyfile.go b/modules/caddypki/acmeserver/caddyfile.go
index fe12712..ae2d8ef 100644
--- a/modules/caddypki/acmeserver/caddyfile.go
+++ b/modules/caddypki/acmeserver/caddyfile.go
@@ -15,6 +15,9 @@
 package acmeserver
 
 import (
+	"time"
+
+	"github.com/caddyserver/caddy/v2"
 	"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
 	"github.com/caddyserver/caddy/v2/modules/caddypki"
 )
@@ -27,6 +30,7 @@ func init() {
 //
 //	acme_server [<matcher>] {
 //	    ca <id>
+//	    lifetime <duration>
 //	}
 func parseACMEServer(h httpcaddyfile.Helper) ([]httpcaddyfile.ConfigValue, error) {
 	if !h.Next() {
@@ -55,6 +59,21 @@ func parseACMEServer(h httpcaddyfile.Helper) ([]httpcaddyfile.ConfigValue, error
 					ca = new(caddypki.CA)
 				}
 				ca.ID = acmeServer.CA
+			case "lifetime":
+				if !h.NextArg() {
+					return nil, h.ArgErr()
+				}
+
+				dur, err := caddy.ParseDuration(h.Val())
+				if err != nil {
+					return nil, err
+				}
+
+				if d := time.Duration(ca.IntermediateLifetime); d > 0 && dur > d {
+					return nil, h.Errf("certificate lifetime (%s) exceeds intermediate certificate lifetime (%s)", dur, d)
+				}
+
+				acmeServer.Lifetime = caddy.Duration(dur)
 			}
 		}
 	}
diff --git a/modules/caddypki/ca.go b/modules/caddypki/ca.go
index 914eddf..1ba0890 100644
--- a/modules/caddypki/ca.go
+++ b/modules/caddypki/ca.go
@@ -48,6 +48,9 @@ type CA struct {
 	// intermediate certificates.
 	IntermediateCommonName string `json:"intermediate_common_name,omitempty"`
 
+	// The lifetime for the intermediate certificates
+	IntermediateLifetime caddy.Duration `json:"intermediate_lifetime,omitempty"`
+
 	// Whether Caddy will attempt to install the CA's root
 	// into the system trust store, as well as into Java
 	// and Mozilla Firefox trust stores. Default: true.
@@ -118,6 +121,11 @@ func (ca *CA) Provision(ctx caddy.Context, id string, log *zap.Logger) error {
 	if ca.IntermediateCommonName == "" {
 		ca.IntermediateCommonName = defaultIntermediateCommonName
 	}
+	if ca.IntermediateLifetime == 0 {
+		ca.IntermediateLifetime = caddy.Duration(defaultIntermediateLifetime)
+	} else if time.Duration(ca.IntermediateLifetime) >= defaultRootLifetime {
+		return fmt.Errorf("intermediate certificate lifetime must be less than root certificate lifetime (%s)", defaultRootLifetime)
+	}
 
 	// load the certs and key that will be used for signing
 	var rootCert, interCert *x509.Certificate
@@ -341,7 +349,7 @@ func (ca CA) loadOrGenIntermediate(rootCert *x509.Certificate, rootKey crypto.Si
 func (ca CA) genIntermediate(rootCert *x509.Certificate, rootKey crypto.Signer) (interCert *x509.Certificate, interKey crypto.Signer, err error) {
 	repl := ca.newReplacer()
 
-	interCert, interKey, err = generateIntermediate(repl.ReplaceAll(ca.IntermediateCommonName, ""), rootCert, rootKey)
+	interCert, interKey, err = generateIntermediate(repl.ReplaceAll(ca.IntermediateCommonName, ""), rootCert, rootKey, time.Duration(ca.IntermediateLifetime))
 	if err != nil {
 		return nil, nil, fmt.Errorf("generating CA intermediate: %v", err)
 	}
diff --git a/modules/caddypki/certificates.go b/modules/caddypki/certificates.go
index c3b88a1..e300429 100644
--- a/modules/caddypki/certificates.go
+++ b/modules/caddypki/certificates.go
@@ -35,8 +35,8 @@ func generateRoot(commonName string) (*x509.Certificate, crypto.Signer, error) {
 	return root, signer, nil
 }
 
-func generateIntermediate(commonName string, rootCrt *x509.Certificate, rootKey crypto.Signer) (*x509.Certificate, crypto.Signer, error) {
-	template, signer, err := newCert(commonName, x509util.DefaultIntermediateTemplate, defaultIntermediateLifetime)
+func generateIntermediate(commonName string, rootCrt *x509.Certificate, rootKey crypto.Signer, lifetime time.Duration) (*x509.Certificate, crypto.Signer, error) {
+	template, signer, err := newCert(commonName, x509util.DefaultIntermediateTemplate, lifetime)
 	if err != nil {
 		return nil, nil, err
 	}