Use Custom Cert Extensions as Cert Auth Constraint (#3634)

builtin/credential/cert/backend_test.go

@@ -619,9 +619,9 @@ func TestBackend_CertWrites(t *testing.T) {
 	tc := logicaltest.TestCase{
 		Backend: testFactory(t),
 		Steps: []logicaltest.TestStep{
-			testAccStepCert(t, "aaa", ca1, "foo", "", false),
-			testAccStepCert(t, "bbb", ca2, "foo", "", false),
-			testAccStepCert(t, "ccc", ca3, "foo", "", true),
+			testAccStepCert(t, "aaa", ca1, "foo", "", "", false),
+			testAccStepCert(t, "bbb", ca2, "foo", "", "", false),
+			testAccStepCert(t, "ccc", ca3, "foo", "", "", true),
 		},
 	}
 	tc.Steps = append(tc.Steps, testAccStepListCerts(t, []string{"aaa", "bbb"})...)
@@ -642,16 +642,16 @@ func TestBackend_basic_CA(t *testing.T) {
 	logicaltest.Test(t, logicaltest.TestCase{
 		Backend: testFactory(t),
 		Steps: []logicaltest.TestStep{
-			testAccStepCert(t, "web", ca, "foo", "", false),
+			testAccStepCert(t, "web", ca, "foo", "", "", false),
 			testAccStepLogin(t, connState),
 			testAccStepCertLease(t, "web", ca, "foo"),
 			testAccStepCertTTL(t, "web", ca, "foo"),
 			testAccStepLogin(t, connState),
 			testAccStepCertNoLease(t, "web", ca, "foo"),
 			testAccStepLoginDefaultLease(t, connState),
-			testAccStepCert(t, "web", ca, "foo", "*.example.com", false),
+			testAccStepCert(t, "web", ca, "foo", "*.example.com", "", false),
 			testAccStepLogin(t, connState),
-			testAccStepCert(t, "web", ca, "foo", "*.invalid.com", false),
+			testAccStepCert(t, "web", ca, "foo", "*.invalid.com", "", false),
 			testAccStepLoginInvalid(t, connState),
 		},
 	})
@@ -700,11 +700,68 @@ func TestBackend_basic_singleCert(t *testing.T) {
 	logicaltest.Test(t, logicaltest.TestCase{
 		Backend: testFactory(t),
 		Steps: []logicaltest.TestStep{
-			testAccStepCert(t, "web", ca, "foo", "", false),
+			testAccStepCert(t, "web", ca, "foo", "", "", false),
 			testAccStepLogin(t, connState),
-			testAccStepCert(t, "web", ca, "foo", "example.com", false),
+			testAccStepCert(t, "web", ca, "foo", "example.com", "", false),
 			testAccStepLogin(t, connState),
-			testAccStepCert(t, "web", ca, "foo", "invalid", false),
+			testAccStepCert(t, "web", ca, "foo", "invalid", "", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "", "1.2.3.4:invalid", false),
+			testAccStepLoginInvalid(t, connState),
+		},
+	})
+}
+
+// Test a self-signed client with custom extensions (root CA) that is trusted
+func TestBackend_extensions_singleCert(t *testing.T) {
+	connState, err := testConnState(
+		"test-fixtures/root/rootcawextcert.pem",
+		"test-fixtures/root/rootcawextkey.pem",
+		"test-fixtures/root/rootcacert.pem",
+	)
+	if err != nil {
+		t.Fatalf("error testing connection state: %v", err)
+	}
+	ca, err := ioutil.ReadFile("test-fixtures/root/rootcacert.pem")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	logicaltest.Test(t, logicaltest.TestCase{
+		Backend: testFactory(t),
+		Steps: []logicaltest.TestStep{
+			testAccStepCert(t, "web", ca, "foo", "", "2.1.1.1:A UTF8String Extension", false),
+			testAccStepLogin(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "", "2.1.1.1:*,2.1.1.2:A UTF8*", false),
+			testAccStepLogin(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "", "1.2.3.45:*", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "", "2.1.1.1:The Wrong Value", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "", "2.1.1.1:*,2.1.1.2:The Wrong Value", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "", "2.1.1.1:", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "", "2.1.1.1:,2.1.1.2:*", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "example.com", "2.1.1.1:A UTF8String Extension", false),
+			testAccStepLogin(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "example.com", "2.1.1.1:*,2.1.1.2:A UTF8*", false),
+			testAccStepLogin(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "example.com", "1.2.3.45:*", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "example.com", "2.1.1.1:The Wrong Value", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "example.com", "2.1.1.1:*,2.1.1.2:The Wrong Value", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "invalid", "2.1.1.1:A UTF8String Extension", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "invalid", "2.1.1.1:*,2.1.1.2:A UTF8*", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "invalid", "1.2.3.45:*", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "invalid", "2.1.1.1:The Wrong Value", false),
+			testAccStepLoginInvalid(t, connState),
+			testAccStepCert(t, "web", ca, "foo", "invalid", "2.1.1.1:*,2.1.1.2:The Wrong Value", false),
 			testAccStepLoginInvalid(t, connState),
 		},
 	})
@@ -724,9 +781,9 @@ func TestBackend_mixed_constraints(t *testing.T) {
 	logicaltest.Test(t, logicaltest.TestCase{
 		Backend: testFactory(t),
 		Steps: []logicaltest.TestStep{
-			testAccStepCert(t, "1unconstrained", ca, "foo", "", false),
-			testAccStepCert(t, "2matching", ca, "foo", "*.example.com,whatever", false),
-			testAccStepCert(t, "3invalid", ca, "foo", "invalid", false),
+			testAccStepCert(t, "1unconstrained", ca, "foo", "", "", false),
+			testAccStepCert(t, "2matching", ca, "foo", "*.example.com,whatever", "", false),
+			testAccStepCert(t, "3invalid", ca, "foo", "invalid", "", false),
 			testAccStepLogin(t, connState),
 			// Assumes CertEntries are processed in alphabetical order (due to store.List), so we only match 2matching if 1unconstrained doesn't match
 			testAccStepLoginWithName(t, connState, "2matching"),
@@ -906,17 +963,18 @@ func testAccStepListCerts(
 }
 
 func testAccStepCert(
-	t *testing.T, name string, cert []byte, policies string, allowedNames string, expectError bool) logicaltest.TestStep {
+	t *testing.T, name string, cert []byte, policies string, allowedNames string, requiredExtensions string, expectError bool) logicaltest.TestStep {
 	return logicaltest.TestStep{
 		Operation: logical.UpdateOperation,
 		Path:      "certs/" + name,
 		ErrorOk:   expectError,
 		Data: map[string]interface{}{
-			"certificate":   string(cert),
-			"policies":      policies,
-			"display_name":  name,
-			"allowed_names": allowedNames,
-			"lease":         1000,
+			"certificate":         string(cert),
+			"policies":            policies,
+			"display_name":        name,
+			"allowed_names":       allowedNames,
+			"required_extensions": requiredExtensions,
+			"lease":               1000,
 		},
 		Check: func(resp *logical.Response) error {
 			if resp == nil && expectError {

builtin/credential/cert/path_certs.go

@@ -45,6 +45,13 @@ Must be x509 PEM encoded.`,
 At least one must exist in either the Common Name or SANs. Supports globbing.`,
 			},
 
+			"required_extensions": &framework.FieldSchema{
+				Type: framework.TypeCommaStringSlice,
+				Description: `A comma-separated string or array of extensions
+formatted as "oid:value". Expects the extension value to be some type of ASN1 encoded string.
+All values much match. Supports globbing on "value".`,
+			},
+
 			"display_name": &framework.FieldSchema{
 				Type: framework.TypeString,
 				Description: `The display name to use for clients using this
@@ -147,6 +154,7 @@ func (b *backend) pathCertWrite(
 	displayName := d.Get("display_name").(string)
 	policies := policyutil.ParsePolicies(d.Get("policies"))
 	allowedNames := d.Get("allowed_names").([]string)
+	requiredExtensions := d.Get("required_extensions").([]string)
 
 	// Default the display name to the certificate name if not given
 	if displayName == "" {
@@ -173,11 +181,12 @@ func (b *backend) pathCertWrite(
 	}
 
 	certEntry := &CertEntry{
-		Name:         name,
-		Certificate:  certificate,
-		DisplayName:  displayName,
-		Policies:     policies,
-		AllowedNames: allowedNames,
+		Name:               name,
+		Certificate:        certificate,
+		DisplayName:        displayName,
+		Policies:           policies,
+		AllowedNames:       allowedNames,
+		RequiredExtensions: requiredExtensions,
 	}
 
 	// Parse the lease duration or default to backend/system default
@@ -205,12 +214,13 @@ func (b *backend) pathCertWrite(
 }
 
 type CertEntry struct {
-	Name         string
-	Certificate  string
-	DisplayName  string
-	Policies     []string
-	TTL          time.Duration
-	AllowedNames []string
+	Name               string
+	Certificate        string
+	DisplayName        string
+	Policies           []string
+	TTL                time.Duration
+	AllowedNames       []string
+	RequiredExtensions []string
 }
 
 const pathCertHelpSyn = `

builtin/credential/cert/path_login.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto/tls"
 	"crypto/x509"
+	"encoding/asn1"
 	"encoding/base64"
 	"encoding/pem"
 	"errors"
@@ -237,28 +238,61 @@ func (b *backend) verifyCredentials(req *logical.Request, d *framework.FieldData
 }
 
 func (b *backend) matchesConstraints(clientCert *x509.Certificate, trustedChain []*x509.Certificate, config *ParsedCert) bool {
+	return !b.checkForChainInCRLs(trustedChain) &&
+		b.matchesNames(clientCert, config) &&
+		b.matchesCertificateExtenions(clientCert, config)
+}
+
+// matchesNames verifies that the certificate matches at least one configured
+// allowed name
+func (b *backend) matchesNames(clientCert *x509.Certificate, config *ParsedCert) bool {
 	// Default behavior (no names) is to allow all names
-	nameMatched := len(config.Entry.AllowedNames) == 0
+	if len(config.Entry.AllowedNames) == 0 {
+		return true
+	}
 	// At least one pattern must match at least one name if any patterns are specified
 	for _, allowedName := range config.Entry.AllowedNames {
 		if glob.Glob(allowedName, clientCert.Subject.CommonName) {
-			nameMatched = true
+			return true
 		}
 
 		for _, name := range clientCert.DNSNames {
 			if glob.Glob(allowedName, name) {
-				nameMatched = true
+				return true
 			}
 		}
 
 		for _, name := range clientCert.EmailAddresses {
 			if glob.Glob(allowedName, name) {
-				nameMatched = true
+				return true
 			}
 		}
 	}
+	return false
+}
 
-	return !b.checkForChainInCRLs(trustedChain) && nameMatched
+// matchesCertificateExtenions verifies that the certificate matches configured
+// required extensions
+func (b *backend) matchesCertificateExtenions(clientCert *x509.Certificate, config *ParsedCert) bool {
+	// Build Client Extensions Map for Constraint Matching
+	// x509 Writes Extensions in ASN1 with a bitstring tag, which results in the field
+	// including its ASN.1 type tag bytes. For the sake of simplicity, assume string type
+	// and drop the tag bytes. And get the number of bytes from the tag.
+	clientExtMap := make(map[string]string, len(clientCert.Extensions))
+	for _, ext := range clientCert.Extensions {
+		var parsedValue string
+		asn1.Unmarshal(ext.Value, &parsedValue)
+		clientExtMap[ext.Id.String()] = parsedValue
+	}
+	// If any of the required extensions don't match the constraint fails
+	for _, requiredExt := range config.Entry.RequiredExtensions {
+		reqExt := strings.SplitN(requiredExt, ":", 2)
+		clientExtValue, clientExtValueOk := clientExtMap[reqExt[0]]
+		if !clientExtValueOk || !glob.Glob(reqExt[1], clientExtValue) {
+			return false
+		}
+	}
+	return true
 }
 
 // loadTrustedCerts is used to load all the trusted certificates from the backend

builtin/credential/cert/test-fixtures/root/rootcacert.srl

@@ -0,0 +1 @@
+92223EAFBBEE17A3

builtin/credential/cert/test-fixtures/root/rootcawext.cnf

@@ -0,0 +1,21 @@
+[ req ]
+default_bits = 2048
+encrypt_key = no
+prompt = no
+default_md = sha256
+req_extensions = req_v3
+distinguished_name = dn
+
+[ dn ]
+CN = example.com
+
+[ req_v3 ]
+subjectAltName = @alt_names
+2.1.1.1=ASN1:UTF8String:A UTF8String Extension
+2.1.1.2=ASN1:UTF8:A UTF8 Extension
+2.1.1.3=ASN1:IA5:An IA5 Extension
+2.1.1.4=ASN1:VISIBLE:A Visible Extension
+
+[ alt_names ]
+DNS.1 = example.com
+IP.1 = 127.0.0.1

builtin/credential/cert/test-fixtures/root/rootcawext.csr

@@ -0,0 +1,19 @@
+-----BEGIN CERTIFICATE REQUEST-----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+-----END CERTIFICATE REQUEST-----

builtin/credential/cert/test-fixtures/root/rootcawextcert.pem

@@ -0,0 +1,20 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

builtin/credential/cert/test-fixtures/root/rootcawextkey.pem

@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----

website/source/api/auth/cert/index.html.md

@@ -33,6 +33,9 @@ Sets a CA cert and associated parameters in a role name.
   the client certificate with a [globbed pattern]
   (https://github.com/ryanuber/go-glob/blob/master/README.md#example). Value is 
   a comma-separated list of patterns.  Authentication requires at least one Name matching at least one pattern.  If not set, defaults to allowing all names.
+- `required_extensions` `(string: "" or array:[])` - Require specific Custom Extension OIDs to exist and match the pattern. 
+   Value is a comma separated string or array of `oid:value`. Expects the extension value to be some type of ASN1 encoded string.
+   All conditions _must_ be met. Supports globbing on `value`.
 - `policies` `(string: "")` - A comma-separated list of policies to set on tokens 
   issued when authenticating against this CA certificate.
 - `display_name` `(string: "")` -   The `display_name` to set on tokens issued 
@@ -93,6 +96,7 @@ $ curl \
     "display_name": "test",
     "policies": "",
     "allowed_names": "",
+    "required_extensions": "",
     "ttl": 2764800
   },
   "warnings": null,
@@ -327,4 +331,4 @@ $ curl \
     "renewable": true,
   }
 }
-```
+```