cloudflare · rpoisel · Sep 2, 2022
diff --git a/config/config.go b/config/config.go
@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"io/ioutil"
+	"net"
 	"regexp"
 	"strconv"
 	"strings"
@@ -19,6 +20,7 @@ import (
 	"github.com/cloudflare/cfssl/helpers"
 	"github.com/cloudflare/cfssl/log"
 	ocspConfig "github.com/cloudflare/cfssl/ocsp/config"
+
 	// empty import of zlint/v3 required to have lints registered.
 	_ "github.com/zmap/zlint/v3"
 	"github.com/zmap/zlint/v3/lint"
@@ -67,9 +69,18 @@ type AuthRemote struct {
 // CAConstraint would verify against (and override) the CA
 // extensions in the given CSR.
 type CAConstraint struct {
-	IsCA           bool `json:"is_ca"`
-	MaxPathLen     int  `json:"max_path_len"`
-	MaxPathLenZero bool `json:"max_path_len_zero"`
+	IsCA                        bool         `json:"is_ca"`
+	MaxPathLen                  int          `json:"max_path_len"`
+	MaxPathLenZero              bool         `json:"max_path_len_zero"`
+	PermittedDNSDomainsCritical bool         `json:"permitted_dns_domains_critical"`
+	PermittedDNSDomains         []string     `json:"permitted_dns_domains"`
+	ExcludedDNSDomains          []string     `json:"excluded_dns_domains"`
+	PermittedIPRanges           []*net.IPNet `json:"permitted_ip_ranges"`
+	ExcludedIPRanges            []*net.IPNet `json:"excluded_ip_ranges"`
+	PermittedEmailAddresses     []string     `json:"permitted_email_addresses"`
+	ExcludedEmailAddresses      []string     `json:"excluded_email_addresses"`
+	PermittedURIDomains         []string     `json:"permitted_uri_domains"`
+	ExcludedURIDomains          []string     `json:"excluded_uri_domains"`
 }
 
 // A SigningProfile stores information that the CA needs to store

diff --git a/config/config_test.go b/config/config_test.go
@@ -255,6 +255,49 @@ var validLocalConfigsWithCAConstraint = []string{
 			}
 		}
 	}`,
+	`{
+		"signing": {
+			"default": {
+				"usages": ["digital signature", "email protection"],
+				"ca_constraint": {
+					"is_ca": true,
+					"max_path_len_zero": true,
+					"permitted_dns_domains_critical": true,
+					"permitted_dns_domains": [
+						".example.com"
+					],
+					"excluded_dns_domains": [
+						".example.com"
+					],
+					"permitted_ip_ranges": [
+						{
+							"IP": "192.168.0.0",
+							"Mask": "//8AAA=="
+						}
+					],
+					"excluded_ip_ranges": [
+						{
+							"IP": "172.16.0.0",
+							"Mask": "//AAAA=="
+						}
+					],
+					"permitted_email_addresses": [
+						"[email protected]"
+					],
+					"excluded_email_addresses": [
+						"[email protected]"
+					],
+					"permitted_uri_domains": [
+						".example.com"
+					],
+					"excluded_uri_domains": [
+						"host.hurzel.com"
+					]
+				},
+				"expiry": "8000h"
+			}
+		}
+	}`,
 }
 
 var copyExtensionWantedlLocalConfig = `
@@ -443,6 +486,7 @@ func TestLoadFile(t *testing.T) {
 		"testdata/valid_config.json",
 		"testdata/valid_config_auth.json",
 		"testdata/valid_config_no_default.json",
+		"testdata/valid_config_ca_constraints.json",
 		"testdata/valid_config_auth_no_default.json",
 	}
 

diff --git a/config/testdata/valid_config_ca_constraints.json b/config/testdata/valid_config_ca_constraints.json
@@ -0,0 +1,46 @@
+{
+	"signing": {
+		"default": {
+			"usages": [
+				"digital signature",
+				"email protection"
+			],
+			"ca_constraint": {
+				"is_ca": true,
+				"max_path_len_zero": true,
+				"permitted_dns_domains_critical": true,
+				"permitted_dns_domains": [
+					".example.com"
+				],
+				"excluded_dns_domains": [
+					".example.com"
+				],
+				"permitted_ip_ranges": [
+					{
+						"IP": "192.168.0.0",
+						"Mask": "//8AAA=="
+					}
+				],
+				"excluded_ip_ranges": [
+					{
+						"IP": "172.16.0.0",
+						"Mask": "//AAAA=="
+					}
+				],
+				"permitted_email_addresses": [
+					"[email protected]"
+				],
+				"excluded_email_addresses": [
+					"[email protected]"
+				],
+				"permitted_uri_domains": [
+					".example.com"
+				],
+				"excluded_uri_domains": [
+					"host.hurzel.com"
+				]
+			},
+			"expiry": "8000h"
+		}
+	}
+}
diff --git a/doc/cmd/cfssl.txt b/doc/cmd/cfssl.txt
@@ -130,6 +130,17 @@ blank.
       Notice the extra "max_path_len_zero" field: Without it, the
       intermediate CA certificate will have no pathlen constraint.
 
+          + RFC 5280 4.2.1.10 Name Constraints
+              + permitted_dns_domains_critical
+              + permitted_dns_domains
+              + excluded_dns_domains
+              + permitted_ip_ranges
+              + excluded_ip_ranges
+              + permitted_email_addresses
+              + excluded_email_addresses
+              + permitted_uri_domains
+              + excluded_uri_domains
+
     + ocsp_no_check: this should be true if the id-pkix-ocsp-nocheck
       extension should be used (RFC 2560 4.2.2.2.1).
 

diff --git a/signer/local/local_test.go b/signer/local/local_test.go
@@ -31,7 +31,7 @@ import (
 	"github.com/cloudflare/cfssl/helpers"
 	"github.com/cloudflare/cfssl/log"
 	"github.com/cloudflare/cfssl/signer"
-	"github.com/google/certificate-transparency-go"
+	ct "github.com/google/certificate-transparency-go"
 	"github.com/zmap/zlint/v3/lint"
 )
 
@@ -963,6 +963,119 @@ func TestCASignPathlen(t *testing.T) {
 	}
 }
 
+func TestCAConstraints(t *testing.T) {
+	var caCerts = []string{testCaFile, testECDSACaFile}
+	var caKeys = []string{testCaKeyFile, testECDSACaKeyFile}
+	var interCSRs = []string{ecdsaInterCSR, rsaInterCSR}
+	var interKeys = []string{ecdsaInterKey, rsaInterKey}
+	var CAPolicy = &config.Signing{
+		Default: &config.SigningProfile{
+			Usage:        []string{"cert sign", "crl sign"},
+			ExpiryString: "1h",
+			Expiry:       1 * time.Hour,
+			CAConstraint: config.CAConstraint{
+				IsCA:                        true,
+				MaxPathLenZero:              true,
+				PermittedDNSDomainsCritical: true,
+				PermittedDNSDomains:         []string{".sub.cloudflare-inter.com"},
+				ExcludedDNSDomains:          []string{".forbidden.cloudflare-inter.com"},
+				PermittedIPRanges: []*net.IPNet{{
+					IP:   net.IP{0xc0, 0xa8, 0x0, 0x0},
+					Mask: net.IPMask{0xff, 0xff, 0x0, 0x0}}},
+				ExcludedIPRanges: []*net.IPNet{{
+					IP:   net.IP{172, 16, 0x0, 0x0},
+					Mask: net.IPMask{0xff, 0xf0, 0x0, 0x0}}},
+				PermittedEmailAddresses: []string{"[email protected]"},
+				ExcludedEmailAddresses:  []string{".illegal.com"},
+				PermittedURIDomains:     []string{".example.com"},
+				ExcludedURIDomains:      []string{"host.illegal.com"}},
+		},
+	}
+	var hostname = "cloudflare-inter.com"
+	// Each RSA or ECDSA root CA issues two intermediate CAs (one ECDSA and one RSA).
+	// For each intermediate CA, use it to issue additional RSA and ECDSA intermediate CSRs.
+	for i, caFile := range caCerts {
+		caKeyFile := caKeys[i]
+		s := newCustomSigner(t, caFile, caKeyFile)
+		s.policy = CAPolicy
+		for j, csr := range interCSRs {
+			csrBytes, _ := ioutil.ReadFile(csr)
+			certBytes, err := s.Sign(signer.SignRequest{Hosts: signer.SplitHosts(hostname), Request: string(csrBytes)})
+			if err != nil {
+				t.Fatal(err)
+			}
+			interCert, err := helpers.ParseCertificatePEM(certBytes)
+			if err != nil {
+				t.Fatal(err)
+			}
+			keyBytes, _ := ioutil.ReadFile(interKeys[j])
+			interKey, _ := helpers.ParsePrivateKeyPEM(keyBytes)
+			interSigner := &Signer{
+				ca:      interCert,
+				priv:    interKey,
+				policy:  CAPolicy,
+				sigAlgo: signer.DefaultSigAlgo(interKey),
+			}
+			for _, anotherCSR := range interCSRs {
+				anotherCSRBytes, _ := ioutil.ReadFile(anotherCSR)
+				bytes, err := interSigner.Sign(
+					signer.SignRequest{
+						Hosts:   signer.SplitHosts(hostname),
+						Request: string(anotherCSRBytes),
+					})
+				if err != nil {
+					t.Fatal(err)
+				}
+				cert, err := helpers.ParseCertificatePEM(bytes)
+				if err != nil {
+					t.Fatal(err)
+				}
+				if cert.SignatureAlgorithm != interSigner.SigAlgo() {
+					t.Fatal("Cert Signature Algorithm does not match the issuer.")
+				}
+				if cert.MaxPathLen != 0 {
+					t.Fatal("CA Cert Max Path is not zero.")
+				}
+				if cert.MaxPathLenZero != true {
+					t.Fatal("CA Cert Max Path is not zero.")
+				}
+				if cert.PermittedDNSDomainsCritical != true {
+					t.Fatal("CA Cert Permitted DNS Domains Critical is not true..")
+				}
+				if !reflect.DeepEqual(cert.PermittedDNSDomains, []string{".sub.cloudflare-inter.com"}) {
+					t.Fatal("CA Cert Permitted DNS Domains is not equal.")
+				}
+				if !reflect.DeepEqual(cert.ExcludedDNSDomains, []string{".forbidden.cloudflare-inter.com"}) {
+					t.Fatal("CA Cert Excluded DNS Domains is not equal.")
+				}
+				if !reflect.DeepEqual(cert.PermittedIPRanges, []*net.IPNet{{
+					IP:   net.IP{0xc0, 0xa8, 0x0, 0x0},
+					Mask: net.IPMask{0xff, 0xff, 0x0, 0x0}}}) {
+					t.Fatal("CA Cert Permitted IP Ranges is not equal.")
+				}
+				if !reflect.DeepEqual(cert.ExcludedIPRanges, []*net.IPNet{{
+					IP:   net.IP{172, 16, 0x0, 0x0},
+					Mask: net.IPMask{0xff, 0xf0, 0x0, 0x0}}}) {
+					t.Fatal("CA Cert Excluded IP Ranges is not equal.")
+				}
+				if !reflect.DeepEqual(cert.PermittedEmailAddresses, []string{"[email protected]"}) {
+					t.Fatal("CA Cert Permitted Email Addresses is not equal.")
+				}
+				if !reflect.DeepEqual(cert.ExcludedEmailAddresses, []string{".illegal.com"}) {
+					t.Fatal("CA Cert Excluded Email Addresses is not equal.")
+				}
+				if !reflect.DeepEqual(cert.PermittedURIDomains, []string{".example.com"}) {
+					t.Fatal("CA Cert Permitted URI Domains is not equal.")
+				}
+				if !reflect.DeepEqual(cert.ExcludedURIDomains, []string{"host.illegal.com"}) {
+					t.Fatal("CA Cert Excluded URI Domains is not equal.")
+				}
+			}
+		}
+	}
+
+}
+
 func TestNoWhitelistSign(t *testing.T) {
 	csrPEM, err := ioutil.ReadFile(fullSubjectCSR)
 	if err != nil {

diff --git a/signer/signer.go b/signer/signer.go
@@ -358,6 +358,15 @@ func FillTemplate(template *x509.Certificate, defaultProfile, profile *config.Si
 		template.DNSNames = nil
 		template.EmailAddresses = nil
 		template.URIs = nil
+		template.PermittedDNSDomainsCritical = profile.CAConstraint.PermittedDNSDomainsCritical
+		template.PermittedDNSDomains = profile.CAConstraint.PermittedDNSDomains
+		template.ExcludedDNSDomains = profile.CAConstraint.ExcludedDNSDomains
+		template.PermittedIPRanges = profile.CAConstraint.PermittedIPRanges
+		template.ExcludedIPRanges = profile.CAConstraint.ExcludedIPRanges
+		template.PermittedEmailAddresses = profile.CAConstraint.PermittedEmailAddresses
+		template.ExcludedEmailAddresses = profile.CAConstraint.ExcludedEmailAddresses
+		template.PermittedURIDomains = profile.CAConstraint.PermittedURIDomains
+		template.ExcludedURIDomains = profile.CAConstraint.ExcludedURIDomains
 	}
 	template.SubjectKeyId = ski