Merge pull request #1061 from smallstep/name-constraints

Name Constraints Validation
This commit is contained in:
Mariano Cano 2022-09-27 10:26:46 -07:00 committed by GitHub
commit fa7c55a0ec
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GPG key ID: 4AEE18F83AFDEB23
9 changed files with 1055 additions and 34 deletions

View file

@ -1,6 +1,7 @@
package authority
import (
"bytes"
"context"
"crypto"
"crypto/sha256"
@ -24,6 +25,7 @@ import (
adminDBNosql "github.com/smallstep/certificates/authority/admin/db/nosql"
"github.com/smallstep/certificates/authority/administrator"
"github.com/smallstep/certificates/authority/config"
"github.com/smallstep/certificates/authority/internal/constraints"
"github.com/smallstep/certificates/authority/policy"
"github.com/smallstep/certificates/authority/provisioner"
"github.com/smallstep/certificates/cas"
@ -52,6 +54,7 @@ type Authority struct {
rootX509Certs []*x509.Certificate
rootX509CertPool *x509.CertPool
federatedX509Certs []*x509.Certificate
intermediateX509Certs []*x509.Certificate
certificates *sync.Map
x509Enforcers []provisioner.CertificateEnforcer
@ -80,7 +83,8 @@ type Authority struct {
authorizeRenewFunc provisioner.AuthorizeRenewFunc
authorizeSSHRenewFunc provisioner.AuthorizeSSHRenewFunc
// Policy engines
// Constraints and Policy engines
constraintsEngine *constraints.Engine
policyEngine *policy.Engine
adminMutex sync.RWMutex
@ -373,6 +377,12 @@ func (a *Authority) init() error {
if err != nil {
return err
}
// If not defined with an option, add intermediates to the list of
// certificates used for name constraints validation at issuance
// time.
if len(a.intermediateX509Certs) == 0 {
a.intermediateX509Certs = append(a.intermediateX509Certs, options.CertificateChain...)
}
}
a.x509CAService, err = cas.New(ctx, options)
if err != nil {
@ -610,6 +620,21 @@ func (a *Authority) init() error {
return err
}
// Load X509 constraints engine.
//
// This is currently only available in CA mode.
if size := len(a.intermediateX509Certs); size > 0 {
last := a.intermediateX509Certs[size-1]
constraintCerts := make([]*x509.Certificate, 0, size+1)
constraintCerts = append(constraintCerts, a.intermediateX509Certs...)
for _, root := range a.rootX509Certs {
if bytes.Equal(last.RawIssuer, root.RawSubject) && bytes.Equal(last.AuthorityKeyId, root.SubjectKeyId) {
constraintCerts = append(constraintCerts, root)
}
}
a.constraintsEngine = constraints.New(constraintCerts...)
}
// Load x509 and SSH Policy Engines
if err := a.reloadPolicyEngines(ctx); err != nil {
return err

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@ -0,0 +1,135 @@
package constraints
import (
"crypto/x509"
"fmt"
"net"
"net/http"
"net/url"
"github.com/smallstep/certificates/errs"
)
// ConstraintError is the typed error that will be returned if a constraint
// error is found.
type ConstraintError struct {
Type string
Name string
Detail string
}
// Error implements the error interface.
func (e ConstraintError) Error() string {
return e.Detail
}
// As implements the As(any) bool interface and allows to use "errors.As()" to
// convert the ConstraintError to an errs.Error.
func (e ConstraintError) As(v any) bool {
if err, ok := v.(**errs.Error); ok {
*err = &errs.Error{
Status: http.StatusForbidden,
Msg: e.Detail,
Err: e,
}
return true
}
return false
}
// Engine implements a constraint validator for DNS names, IP addresses, Email
// addresses and URIs.
type Engine struct {
hasNameConstraints bool
permittedDNSDomains []string
excludedDNSDomains []string
permittedIPRanges []*net.IPNet
excludedIPRanges []*net.IPNet
permittedEmailAddresses []string
excludedEmailAddresses []string
permittedURIDomains []string
excludedURIDomains []string
}
// New creates a constraint validation engine that contains the given chain of
// certificates.
func New(chain ...*x509.Certificate) *Engine {
e := new(Engine)
for _, crt := range chain {
e.permittedDNSDomains = append(e.permittedDNSDomains, crt.PermittedDNSDomains...)
e.excludedDNSDomains = append(e.excludedDNSDomains, crt.ExcludedDNSDomains...)
e.permittedIPRanges = append(e.permittedIPRanges, crt.PermittedIPRanges...)
e.excludedIPRanges = append(e.excludedIPRanges, crt.ExcludedIPRanges...)
e.permittedEmailAddresses = append(e.permittedEmailAddresses, crt.PermittedEmailAddresses...)
e.excludedEmailAddresses = append(e.excludedEmailAddresses, crt.ExcludedEmailAddresses...)
e.permittedURIDomains = append(e.permittedURIDomains, crt.PermittedURIDomains...)
e.excludedURIDomains = append(e.excludedURIDomains, crt.ExcludedURIDomains...)
}
e.hasNameConstraints = len(e.permittedDNSDomains) > 0 || len(e.excludedDNSDomains) > 0 ||
len(e.permittedIPRanges) > 0 || len(e.excludedIPRanges) > 0 ||
len(e.permittedEmailAddresses) > 0 || len(e.excludedEmailAddresses) > 0 ||
len(e.permittedURIDomains) > 0 || len(e.excludedURIDomains) > 0
return e
}
// Validate checks the given names with the name constraints defined in the
// service.
func (e *Engine) Validate(dnsNames []string, ipAddresses []net.IP, emailAddresses []string, uris []*url.URL) error {
if e == nil || !e.hasNameConstraints {
return nil
}
for _, name := range dnsNames {
if err := checkNameConstraints("DNS name", name, name, e.permittedDNSDomains, e.excludedDNSDomains,
func(parsedName, constraint any) (bool, error) {
return matchDomainConstraint(parsedName.(string), constraint.(string))
},
); err != nil {
return err
}
}
for _, ip := range ipAddresses {
if err := checkNameConstraints("IP address", ip.String(), ip, e.permittedIPRanges, e.excludedIPRanges,
func(parsedName, constraint any) (bool, error) {
return matchIPConstraint(parsedName.(net.IP), constraint.(*net.IPNet))
},
); err != nil {
return err
}
}
for _, email := range emailAddresses {
mailbox, ok := parseRFC2821Mailbox(email)
if !ok {
return fmt.Errorf("cannot parse rfc822Name %q", email)
}
if err := checkNameConstraints("Email address", email, mailbox, e.permittedEmailAddresses, e.excludedEmailAddresses,
func(parsedName, constraint any) (bool, error) {
return matchEmailConstraint(parsedName.(rfc2821Mailbox), constraint.(string))
},
); err != nil {
return err
}
}
for _, uri := range uris {
if err := checkNameConstraints("URI", uri.String(), uri, e.permittedURIDomains, e.excludedURIDomains,
func(parsedName, constraint any) (bool, error) {
return matchURIConstraint(parsedName.(*url.URL), constraint.(string))
},
); err != nil {
return err
}
}
return nil
}
// ValidateCertificate validates the DNS names, IP addresses, Email addresses
// and URIs present in the given certificate.
func (e *Engine) ValidateCertificate(cert *x509.Certificate) error {
return e.Validate(cert.DNSNames, cert.IPAddresses, cert.EmailAddresses, cert.URIs)
}

View file

@ -0,0 +1,334 @@
package constraints
import (
"crypto/x509"
"net"
"net/url"
"reflect"
"testing"
"go.step.sm/crypto/minica"
)
func TestNew(t *testing.T) {
ca1, err := minica.New()
if err != nil {
t.Fatal(err)
}
ca2, err := minica.New(
minica.WithIntermediateTemplate(`{
"subject": {{ toJson .Subject }},
"keyUsage": ["certSign", "crlSign"],
"basicConstraints": {
"isCA": true,
"maxPathLen": 0
},
"nameConstraints": {
"critical": true,
"permittedDNSDomains": ["internal.example.org"],
"excludedDNSDomains": ["internal.example.com"],
"permittedIPRanges": ["192.168.1.0/24", "192.168.2.1/32"],
"excludedIPRanges": ["192.168.3.0/24", "192.168.4.0/28"],
"permittedEmailAddresses": ["root@example.org", "example.org", ".acme.org"],
"excludedEmailAddresses": ["root@example.com", "example.com", ".acme.com"],
"permittedURIDomains": ["host.example.org", ".acme.org"],
"excludedURIDomains": ["host.example.com", ".acme.com"]
}
}`),
)
if err != nil {
t.Fatal(err)
}
type args struct {
chain []*x509.Certificate
}
tests := []struct {
name string
args args
want *Engine
}{
{"ok", args{[]*x509.Certificate{ca1.Intermediate, ca1.Root}}, &Engine{
hasNameConstraints: false,
}},
{"ok with constraints", args{[]*x509.Certificate{ca2.Intermediate, ca2.Root}}, &Engine{
hasNameConstraints: true,
permittedDNSDomains: []string{"internal.example.org"},
excludedDNSDomains: []string{"internal.example.com"},
permittedIPRanges: []*net.IPNet{
{IP: net.ParseIP("192.168.1.0").To4(), Mask: net.IPMask{255, 255, 255, 0}},
{IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}},
},
excludedIPRanges: []*net.IPNet{
{IP: net.ParseIP("192.168.3.0").To4(), Mask: net.IPMask{255, 255, 255, 0}},
{IP: net.ParseIP("192.168.4.0").To4(), Mask: net.IPMask{255, 255, 255, 240}},
},
permittedEmailAddresses: []string{"root@example.org", "example.org", ".acme.org"},
excludedEmailAddresses: []string{"root@example.com", "example.com", ".acme.com"},
permittedURIDomains: []string{"host.example.org", ".acme.org"},
excludedURIDomains: []string{"host.example.com", ".acme.com"},
}},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if got := New(tt.args.chain...); !reflect.DeepEqual(got, tt.want) {
t.Errorf("New() = %v, want %v", got, tt.want)
}
})
}
}
func TestNew_hasNameConstraints(t *testing.T) {
tests := []struct {
name string
fn func(c *x509.Certificate)
want bool
}{
{"no constraints", func(c *x509.Certificate) {}, false},
{"permittedDNSDomains", func(c *x509.Certificate) { c.PermittedDNSDomains = []string{"constraint"} }, true},
{"excludedDNSDomains", func(c *x509.Certificate) { c.ExcludedDNSDomains = []string{"constraint"} }, true},
{"permittedIPRanges", func(c *x509.Certificate) {
c.PermittedIPRanges = []*net.IPNet{{IP: net.ParseIP("192.168.3.0").To4(), Mask: net.IPMask{255, 255, 255, 0}}}
}, true},
{"excludedIPRanges", func(c *x509.Certificate) {
c.ExcludedIPRanges = []*net.IPNet{{IP: net.ParseIP("192.168.3.0").To4(), Mask: net.IPMask{255, 255, 255, 0}}}
}, true},
{"permittedEmailAddresses", func(c *x509.Certificate) { c.PermittedEmailAddresses = []string{"constraint"} }, true},
{"excludedEmailAddresses", func(c *x509.Certificate) { c.ExcludedEmailAddresses = []string{"constraint"} }, true},
{"permittedURIDomains", func(c *x509.Certificate) { c.PermittedURIDomains = []string{"constraint"} }, true},
{"excludedURIDomains", func(c *x509.Certificate) { c.ExcludedURIDomains = []string{"constraint"} }, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
cert := &x509.Certificate{}
tt.fn(cert)
if e := New(cert); e.hasNameConstraints != tt.want {
t.Errorf("Engine.hasNameConstraints = %v, want %v", e.hasNameConstraints, tt.want)
}
})
}
}
func TestEngine_Validate(t *testing.T) {
type fields struct {
hasNameConstraints bool
permittedDNSDomains []string
excludedDNSDomains []string
permittedIPRanges []*net.IPNet
excludedIPRanges []*net.IPNet
permittedEmailAddresses []string
excludedEmailAddresses []string
permittedURIDomains []string
excludedURIDomains []string
}
type args struct {
dnsNames []string
ipAddresses []net.IP
emailAddresses []string
uris []*url.URL
}
tests := []struct {
name string
fields fields
args args
wantErr bool
}{
{"ok", fields{hasNameConstraints: false}, args{
dnsNames: []string{"example.com", "host.example.com"},
ipAddresses: []net.IP{{192, 168, 1, 1}, {0x26, 0x00, 0x1f, 0x1c, 0x47, 0x01, 0x9d, 0x00, 0xc3, 0xa7, 0x66, 0x94, 0x87, 0x0f, 0x20, 0x72}},
emailAddresses: []string{"root@example.com"},
uris: []*url.URL{{Scheme: "https", Host: "example.com", Path: "/uuid/c6d1a755-0c12-431e-9136-b64cb3173ec7"}},
}, false},
{"ok permitted dns", fields{
hasNameConstraints: true,
permittedDNSDomains: []string{"example.com"},
}, args{dnsNames: []string{"example.com", "www.example.com"}}, false},
{"ok not excluded dns", fields{
hasNameConstraints: true,
excludedDNSDomains: []string{"example.org"},
}, args{dnsNames: []string{"example.com", "www.example.com"}}, false},
{"ok permitted ip", fields{
hasNameConstraints: true,
permittedIPRanges: []*net.IPNet{
{IP: net.ParseIP("192.168.1.0"), Mask: net.IPMask{255, 255, 255, 0}},
{IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}},
{IP: net.ParseIP("2600:1700:22f8:2600:e559:bd88:350a:34d6"), Mask: net.IPMask{255, 255, 255, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}},
},
}, args{ipAddresses: []net.IP{{192, 168, 1, 10}, {192, 168, 2, 1}, {0x26, 0x0, 0x17, 0x00, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, 0xb, 0xc}}}, false},
{"ok not excluded ip", fields{
hasNameConstraints: true,
excludedIPRanges: []*net.IPNet{
{IP: net.ParseIP("192.168.1.0"), Mask: net.IPMask{255, 255, 255, 0}},
{IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}},
},
}, args{ipAddresses: []net.IP{{192, 168, 2, 2}, {192, 168, 3, 1}}}, false},
{"ok permitted emails", fields{
hasNameConstraints: true,
permittedEmailAddresses: []string{"root@example.com", "acme.org", ".acme.com"},
}, args{emailAddresses: []string{"root@example.com", "name@acme.org", "name@coyote.acme.com", `"(quoted)"@www.acme.com`}}, false},
{"ok not excluded emails", fields{
hasNameConstraints: true,
excludedEmailAddresses: []string{"root@example.com", "acme.org", ".acme.com"},
}, args{emailAddresses: []string{"name@example.com", "root@acme.com", "root@other.com"}}, false},
{"ok permitted uris", fields{
hasNameConstraints: true,
permittedURIDomains: []string{"example.com", ".acme.com"},
}, args{uris: []*url.URL{{Scheme: "https", Host: "example.com", Path: "/path"}, {Scheme: "https", Host: "www.acme.com", Path: "/path"}}}, false},
{"ok not excluded uris", fields{
hasNameConstraints: true,
excludedURIDomains: []string{"example.com", ".acme.com"},
}, args{uris: []*url.URL{{Scheme: "https", Host: "example.org", Path: "/path"}, {Scheme: "https", Host: "acme.com", Path: "/path"}}}, false},
{"fail permitted dns", fields{
hasNameConstraints: true,
permittedDNSDomains: []string{"example.com"},
}, args{dnsNames: []string{"www.example.com", "www.example.org"}}, true},
{"fail not excluded dns", fields{
hasNameConstraints: true,
excludedDNSDomains: []string{"example.org"},
}, args{dnsNames: []string{"example.com", "www.example.org"}}, true},
{"fail permitted ip", fields{
hasNameConstraints: true,
permittedIPRanges: []*net.IPNet{
{IP: net.ParseIP("192.168.1.0").To4(), Mask: net.IPMask{255, 255, 255, 0}},
{IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}},
},
}, args{ipAddresses: []net.IP{{192, 168, 1, 10}, {192, 168, 2, 10}}}, true},
{"fail not excluded ip", fields{
hasNameConstraints: true,
excludedIPRanges: []*net.IPNet{
{IP: net.ParseIP("192.168.1.0").To4(), Mask: net.IPMask{255, 255, 255, 0}},
{IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}},
},
}, args{ipAddresses: []net.IP{{192, 168, 2, 2}, {192, 168, 1, 1}}}, true},
{"fail permitted emails", fields{
hasNameConstraints: true,
permittedEmailAddresses: []string{"root@example.com", "acme.org", ".acme.com"},
}, args{emailAddresses: []string{"root@example.com", "name@acme.org", "name@acme.com"}}, true},
{"fail not excluded emails", fields{
hasNameConstraints: true,
excludedEmailAddresses: []string{"root@example.com", "acme.org", ".acme.com"},
}, args{emailAddresses: []string{"name@example.com", "root@example.com"}}, true},
{"fail permitted uris", fields{
hasNameConstraints: true,
permittedURIDomains: []string{"example.com", ".acme.com"},
}, args{uris: []*url.URL{{Scheme: "https", Host: "example.com", Path: "/path"}, {Scheme: "https", Host: "acme.com", Path: "/path"}}}, true},
{"fail not excluded uris", fields{
hasNameConstraints: true,
excludedURIDomains: []string{"example.com", ".acme.com"},
}, args{uris: []*url.URL{{Scheme: "https", Host: "www.example.com", Path: "/path"}, {Scheme: "https", Host: "acme.com", Path: "/path"}}}, true},
{"fail parse emails", fields{
hasNameConstraints: true,
permittedEmailAddresses: []string{"example.com"},
}, args{emailAddresses: []string{`(notquoted)@example.com`}}, true},
{"fail match dns", fields{
hasNameConstraints: true,
permittedDNSDomains: []string{"example.com"},
}, args{dnsNames: []string{`www.example.com.`}}, true},
{"fail match email", fields{
hasNameConstraints: true,
excludedEmailAddresses: []string{`(notquoted)@example.com`},
}, args{emailAddresses: []string{`ok@example.com`}}, true},
{"fail match uri", fields{
hasNameConstraints: true,
permittedURIDomains: []string{"example.com"},
}, args{uris: []*url.URL{{Scheme: "urn", Opaque: "uuid:36efb1ae-6617-4b23-b799-874a37aaea1c"}}}, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
e := &Engine{
hasNameConstraints: tt.fields.hasNameConstraints,
permittedDNSDomains: tt.fields.permittedDNSDomains,
excludedDNSDomains: tt.fields.excludedDNSDomains,
permittedIPRanges: tt.fields.permittedIPRanges,
excludedIPRanges: tt.fields.excludedIPRanges,
permittedEmailAddresses: tt.fields.permittedEmailAddresses,
excludedEmailAddresses: tt.fields.excludedEmailAddresses,
permittedURIDomains: tt.fields.permittedURIDomains,
excludedURIDomains: tt.fields.excludedURIDomains,
}
if err := e.Validate(tt.args.dnsNames, tt.args.ipAddresses, tt.args.emailAddresses, tt.args.uris); (err != nil) != tt.wantErr {
t.Errorf("service.Validate() error = %v, wantErr %v", err, tt.wantErr)
}
})
}
}
func TestEngine_Validate_nil(t *testing.T) {
var e *Engine
if err := e.Validate([]string{"www.example.com"}, nil, nil, nil); err != nil {
t.Errorf("service.Validate() error = %v, wantErr false", err)
}
}
func TestEngine_ValidateCertificate(t *testing.T) {
type fields struct {
hasNameConstraints bool
permittedDNSDomains []string
excludedDNSDomains []string
permittedIPRanges []*net.IPNet
excludedIPRanges []*net.IPNet
permittedEmailAddresses []string
excludedEmailAddresses []string
permittedURIDomains []string
excludedURIDomains []string
}
type args struct {
cert *x509.Certificate
}
tests := []struct {
name string
fields fields
args args
wantErr bool
}{
{"ok", fields{hasNameConstraints: false}, args{&x509.Certificate{
DNSNames: []string{"example.com"},
IPAddresses: []net.IP{{127, 0, 0, 1}},
EmailAddresses: []string{"info@example.com"},
URIs: []*url.URL{{Scheme: "https", Host: "uuid.example.com", Path: "/dc4c76b5-5262-4551-a881-48094a604d63"}},
}}, false},
{"ok with constraints", fields{
hasNameConstraints: true,
permittedDNSDomains: []string{"example.com"},
permittedIPRanges: []*net.IPNet{
{IP: net.ParseIP("127.0.0.1").To4(), Mask: net.IPMask{255, 255, 255, 255}},
{IP: net.ParseIP("10.3.0.0").To4(), Mask: net.IPMask{255, 255, 0, 0}},
},
permittedEmailAddresses: []string{"example.com"},
permittedURIDomains: []string{".example.com"},
}, args{&x509.Certificate{
DNSNames: []string{"www.example.com"},
IPAddresses: []net.IP{{127, 0, 0, 1}, {10, 3, 1, 1}},
EmailAddresses: []string{"info@example.com"},
URIs: []*url.URL{{Scheme: "https", Host: "uuid.example.com", Path: "/dc4c76b5-5262-4551-a881-48094a604d63"}},
}}, false},
{"fail", fields{
hasNameConstraints: true,
permittedURIDomains: []string{".example.com"},
}, args{&x509.Certificate{
DNSNames: []string{"example.com"},
IPAddresses: []net.IP{{127, 0, 0, 1}},
EmailAddresses: []string{"info@example.com"},
URIs: []*url.URL{{Scheme: "https", Host: "uuid.example.org", Path: "/dc4c76b5-5262-4551-a881-48094a604d63"}},
}}, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
e := &Engine{
hasNameConstraints: tt.fields.hasNameConstraints,
permittedDNSDomains: tt.fields.permittedDNSDomains,
excludedDNSDomains: tt.fields.excludedDNSDomains,
permittedIPRanges: tt.fields.permittedIPRanges,
excludedIPRanges: tt.fields.excludedIPRanges,
permittedEmailAddresses: tt.fields.permittedEmailAddresses,
excludedEmailAddresses: tt.fields.excludedEmailAddresses,
permittedURIDomains: tt.fields.permittedURIDomains,
excludedURIDomains: tt.fields.excludedURIDomains,
}
if err := e.ValidateCertificate(tt.args.cert); (err != nil) != tt.wantErr {
t.Errorf("Engine.ValidateCertificate() error = %v, wantErr %v", err, tt.wantErr)
}
})
}
}

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@ -0,0 +1,383 @@
// Copyright (c) 2009 The Go Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package constraints
import (
"bytes"
"fmt"
"net"
"net/url"
"reflect"
"strings"
)
func checkNameConstraints(nameType, name string, parsedName, permitted, excluded any, match func(name, constraint any) (bool, error)) error {
excludedValue := reflect.ValueOf(excluded)
for i := 0; i < excludedValue.Len(); i++ {
constraint := excludedValue.Index(i).Interface()
match, err := match(parsedName, constraint)
if err != nil {
return ConstraintError{
Type: nameType,
Name: name,
Detail: err.Error(),
}
}
if match {
return ConstraintError{
Type: nameType,
Name: name,
Detail: fmt.Sprintf("%s %q is excluded by constraint %q", nameType, name, constraint),
}
}
}
var (
err error
ok = true
)
permittedValue := reflect.ValueOf(permitted)
for i := 0; i < permittedValue.Len(); i++ {
constraint := permittedValue.Index(i).Interface()
if ok, err = match(parsedName, constraint); err != nil {
return ConstraintError{
Type: nameType,
Name: name,
Detail: err.Error(),
}
}
if ok {
break
}
}
if !ok {
return ConstraintError{
Type: nameType,
Name: name,
Detail: fmt.Sprintf("%s %q is not permitted by any constraint", nameType, name),
}
}
return nil
}
func matchDomainConstraint(domain, constraint string) (bool, error) {
// The meaning of zero length constraints is not specified, but this
// code follows NSS and accepts them as matching everything.
if constraint == "" {
return true, nil
}
domainLabels, ok := domainToReverseLabels(domain)
if !ok {
return false, fmt.Errorf("internal error: cannot parse domain %q", domain)
}
// RFC 5280 says that a leading period in a domain name means that at least
// one label must be prepended, but only for URI and email constraints, not
// DNS constraints. The code also supports that behavior for DNS
// constraints.
mustHaveSubdomains := false
if constraint[0] == '.' {
mustHaveSubdomains = true
constraint = constraint[1:]
}
constraintLabels, ok := domainToReverseLabels(constraint)
if !ok {
return false, fmt.Errorf("internal error: cannot parse domain %q", constraint)
}
if len(domainLabels) < len(constraintLabels) ||
(mustHaveSubdomains && len(domainLabels) == len(constraintLabels)) {
return false, nil
}
for i, constraintLabel := range constraintLabels {
if !strings.EqualFold(constraintLabel, domainLabels[i]) {
return false, nil
}
}
return true, nil
}
func normalizeIP(ip net.IP) net.IP {
if ip4 := ip.To4(); ip4 != nil {
return ip4
}
return ip
}
func matchIPConstraint(ip net.IP, constraint *net.IPNet) (bool, error) {
ip = normalizeIP(ip)
constraintIP := normalizeIP(constraint.IP)
if len(ip) != len(constraintIP) {
return false, nil
}
for i := range ip {
if mask := constraint.Mask[i]; ip[i]&mask != constraintIP[i]&mask {
return false, nil
}
}
return true, nil
}
func matchEmailConstraint(mailbox rfc2821Mailbox, constraint string) (bool, error) {
// If the constraint contains an @, then it specifies an exact mailbox
// name.
if strings.Contains(constraint, "@") {
constraintMailbox, ok := parseRFC2821Mailbox(constraint)
if !ok {
return false, fmt.Errorf("internal error: cannot parse constraint %q", constraint)
}
return mailbox.local == constraintMailbox.local && strings.EqualFold(mailbox.domain, constraintMailbox.domain), nil
}
// Otherwise the constraint is like a DNS constraint of the domain part
// of the mailbox.
return matchDomainConstraint(mailbox.domain, constraint)
}
func matchURIConstraint(uri *url.URL, constraint string) (bool, error) {
// From RFC 5280, Section 4.2.1.10:
// “a uniformResourceIdentifier that does not include an authority
// component with a host name specified as a fully qualified domain
// name (e.g., if the URI either does not include an authority
// component or includes an authority component in which the host name
// is specified as an IP address), then the application MUST reject the
// certificate.”
host := uri.Host
if host == "" {
return false, fmt.Errorf("URI with empty host (%q) cannot be matched against constraints", uri.String())
}
if strings.Contains(host, ":") && !strings.HasSuffix(host, "]") {
var err error
host, _, err = net.SplitHostPort(uri.Host)
if err != nil {
return false, err
}
}
if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") ||
net.ParseIP(host) != nil {
return false, fmt.Errorf("URI with IP (%q) cannot be matched against constraints", uri.String())
}
return matchDomainConstraint(host, constraint)
}
// domainToReverseLabels converts a textual domain name like foo.example.com to
// the list of labels in reverse order, e.g. ["com", "example", "foo"].
func domainToReverseLabels(domain string) (reverseLabels []string, ok bool) {
for len(domain) > 0 {
if i := strings.LastIndexByte(domain, '.'); i == -1 {
reverseLabels = append(reverseLabels, domain)
domain = ""
} else {
reverseLabels = append(reverseLabels, domain[i+1:])
domain = domain[:i]
}
}
if len(reverseLabels) > 0 && reverseLabels[0] == "" {
// An empty label at the end indicates an absolute value.
return nil, false
}
for _, label := range reverseLabels {
if label == "" {
// Empty labels are otherwise invalid.
return nil, false
}
for _, c := range label {
if c < 33 || c > 126 {
// Invalid character.
return nil, false
}
}
}
return reverseLabels, true
}
// rfc2821Mailbox represents a “mailbox” (which is an email address to most
// people) by breaking it into the “local” (i.e. before the '@') and “domain”
// parts.
type rfc2821Mailbox struct {
local, domain string
}
// parseRFC2821Mailbox parses an email address into local and domain parts,
// based on the ABNF for a “Mailbox” from RFC 2821. According to RFC 5280,
// Section 4.2.1.6 that's correct for an rfc822Name from a certificate: “The
// format of an rfc822Name is a "Mailbox" as defined in RFC 2821, Section 4.1.2”.
func parseRFC2821Mailbox(in string) (mailbox rfc2821Mailbox, ok bool) {
if in == "" {
return mailbox, false
}
localPartBytes := make([]byte, 0, len(in)/2)
if in[0] == '"' {
// Quoted-string = DQUOTE *qcontent DQUOTE
// non-whitespace-control = %d1-8 / %d11 / %d12 / %d14-31 / %d127
// qcontent = qtext / quoted-pair
// qtext = non-whitespace-control /
// %d33 / %d35-91 / %d93-126
// quoted-pair = ("\" text) / obs-qp
// text = %d1-9 / %d11 / %d12 / %d14-127 / obs-text
//
// (Names beginning with “obs-” are the obsolete syntax from RFC 2822,
// Section 4. Since it has been 16 years, we no longer accept that.)
in = in[1:]
QuotedString:
for {
if in == "" {
return mailbox, false
}
c := in[0]
in = in[1:]
switch {
case c == '"':
break QuotedString
case c == '\\':
// quoted-pair
if in == "" {
return mailbox, false
}
if in[0] == 11 ||
in[0] == 12 ||
(1 <= in[0] && in[0] <= 9) ||
(14 <= in[0] && in[0] <= 127) {
localPartBytes = append(localPartBytes, in[0])
in = in[1:]
} else {
return mailbox, false
}
case c == 11 ||
c == 12 ||
// Space (char 32) is not allowed based on the
// BNF, but RFC 3696 gives an example that
// assumes that it is. Several “verified”
// errata continue to argue about this point.
// We choose to accept it.
c == 32 ||
c == 33 ||
c == 127 ||
(1 <= c && c <= 8) ||
(14 <= c && c <= 31) ||
(35 <= c && c <= 91) ||
(93 <= c && c <= 126):
// qtext
localPartBytes = append(localPartBytes, c)
default:
return mailbox, false
}
}
} else {
// Atom ("." Atom)*
NextChar:
for len(in) > 0 {
// atext from RFC 2822, Section 3.2.4
c := in[0]
switch {
case c == '\\':
// Examples given in RFC 3696 suggest that
// escaped characters can appear outside of a
// quoted string. Several “verified” errata
// continue to argue the point. We choose to
// accept it.
in = in[1:]
if in == "" {
return mailbox, false
}
fallthrough
case ('0' <= c && c <= '9') ||
('a' <= c && c <= 'z') ||
('A' <= c && c <= 'Z') ||
c == '!' || c == '#' || c == '$' || c == '%' ||
c == '&' || c == '\'' || c == '*' || c == '+' ||
c == '-' || c == '/' || c == '=' || c == '?' ||
c == '^' || c == '_' || c == '`' || c == '{' ||
c == '|' || c == '}' || c == '~' || c == '.':
localPartBytes = append(localPartBytes, in[0])
in = in[1:]
default:
break NextChar
}
}
if len(localPartBytes) == 0 {
return mailbox, false
}
// From RFC 3696, Section 3:
// “period (".") may also appear, but may not be used to start
// or end the local part, nor may two or more consecutive
// periods appear.”
twoDots := []byte{'.', '.'}
if localPartBytes[0] == '.' ||
localPartBytes[len(localPartBytes)-1] == '.' ||
bytes.Contains(localPartBytes, twoDots) {
return mailbox, false
}
}
if in == "" || in[0] != '@' {
return mailbox, false
}
in = in[1:]
// The RFC species a format for domains, but that's known to be
// violated in practice so we accept that anything after an '@' is the
// domain part.
if _, ok := domainToReverseLabels(in); !ok {
return mailbox, false
}
mailbox.local = string(localPartBytes)
mailbox.domain = in
return mailbox, true
}

View file

@ -151,16 +151,23 @@ func WithKeyManager(k kms.KeyManager) Option {
// WithX509Signer defines the signer used to sign X509 certificates.
func WithX509Signer(crt *x509.Certificate, s crypto.Signer) Option {
return WithX509SignerChain([]*x509.Certificate{crt}, s)
}
// WithX509SignerChain defines the signer used to sign X509 certificates. This
// option is similar to WithX509Signer but it supports a chain of intermediates.
func WithX509SignerChain(issuerChain []*x509.Certificate, s crypto.Signer) Option {
return func(a *Authority) error {
srv, err := cas.New(context.Background(), casapi.Options{
Type: casapi.SoftCAS,
Signer: s,
CertificateChain: []*x509.Certificate{crt},
CertificateChain: issuerChain,
})
if err != nil {
return err
}
a.x509CAService = srv
a.intermediateX509Certs = append(a.intermediateX509Certs, issuerChain...)
return nil
}
}
@ -233,6 +240,25 @@ func WithX509FederatedCerts(certs ...*x509.Certificate) Option {
}
}
// WithX509IntermediateCerts is an option that allows to define the list of
// intermediate certificates that the CA will be using. This option will replace
// any intermediate certificate defined before.
//
// Note that these certificates will not be bundled with the certificates signed
// by the CA, because the CAS service will take care of that. They should match,
// but that's not guaranteed. These certificates will be mainly used for name
// constraint validation before a certificate is issued.
//
// This option should only be used on specific configurations, for example when
// WithX509SignerFunc is used, as we don't know the list of intermediates in
// advance.
func WithX509IntermediateCerts(intermediateCerts ...*x509.Certificate) Option {
return func(a *Authority) error {
a.intermediateX509Certs = intermediateCerts
return nil
}
}
// WithX509RootBundle is an option that allows to define the list of root
// certificates. This option will replace any root certificate defined before.
func WithX509RootBundle(pemCerts []byte) Option {

View file

@ -6,7 +6,6 @@ import (
"crypto/x509"
"encoding/binary"
"errors"
"fmt"
"net/http"
"strings"
"time"
@ -20,7 +19,6 @@ import (
"github.com/smallstep/certificates/authority/provisioner"
"github.com/smallstep/certificates/db"
"github.com/smallstep/certificates/errs"
policy "github.com/smallstep/certificates/policy"
"github.com/smallstep/certificates/templates"
)
@ -255,15 +253,9 @@ func (a *Authority) SignSSH(ctx context.Context, key ssh.PublicKey, opts provisi
// Check if authority is allowed to sign the certificate
if err := a.isAllowedToSignSSHCertificate(certTpl); err != nil {
var pe *policy.NamePolicyError
if errors.As(err, &pe) && pe.Reason == policy.NotAllowed {
return nil, &errs.Error{
// NOTE: custom forbidden error, so that denied name is sent to client
// as well as shown in the logs.
Status: http.StatusForbidden,
Err: fmt.Errorf("authority not allowed to sign: %w", err),
Msg: fmt.Sprintf("The request was forbidden by the certificate authority: %s", err.Error()),
}
var ee *errs.Error
if errors.As(err, &ee) {
return nil, ee
}
return nil, errs.InternalServerErr(err,
errs.WithMessage("authority.SignSSH: error creating ssh certificate"),

View file

@ -28,7 +28,6 @@ import (
casapi "github.com/smallstep/certificates/cas/apiv1"
"github.com/smallstep/certificates/db"
"github.com/smallstep/certificates/errs"
"github.com/smallstep/certificates/policy"
)
// GetTLSOptions returns the tls options configured.
@ -213,15 +212,9 @@ func (a *Authority) Sign(csr *x509.CertificateRequest, signOpts provisioner.Sign
// Check if authority is allowed to sign the certificate
if err := a.isAllowedToSignX509Certificate(leaf); err != nil {
var pe *policy.NamePolicyError
if errors.As(err, &pe) && pe.Reason == policy.NotAllowed {
return nil, errs.ApplyOptions(&errs.Error{
// NOTE: custom forbidden error, so that denied name is sent to client
// as well as shown in the logs.
Status: http.StatusForbidden,
Err: fmt.Errorf("authority not allowed to sign: %w", err),
Msg: fmt.Sprintf("The request was forbidden by the certificate authority: %s", err.Error()),
}, opts...)
var ee *errs.Error
if errors.As(err, &ee) {
return nil, errs.ApplyOptions(ee, opts...)
}
return nil, errs.InternalServerErr(err,
errs.WithKeyVal("csr", csr),
@ -257,6 +250,9 @@ func (a *Authority) Sign(csr *x509.CertificateRequest, signOpts provisioner.Sign
// isAllowedToSignX509Certificate checks if the Authority is allowed
// to sign the X.509 certificate.
func (a *Authority) isAllowedToSignX509Certificate(cert *x509.Certificate) error {
if err := a.constraintsEngine.ValidateCertificate(cert); err != nil {
return err
}
return a.policyEngine.IsX509CertificateAllowed(cert)
}
@ -352,6 +348,22 @@ func (a *Authority) Rekey(oldCert *x509.Certificate, pk crypto.PublicKey) ([]*x5
newCert.ExtraExtensions = append(newCert.ExtraExtensions, ext)
}
// Check if the certificate is allowed to be renewed, name constraints might
// change over time.
//
// TODO(hslatman,maraino): consider adding policies too and consider if
// RenewSSH should check policies.
if err := a.constraintsEngine.ValidateCertificate(newCert); err != nil {
var ee *errs.Error
if errors.As(err, &ee) {
return nil, errs.ApplyOptions(ee, opts...)
}
return nil, errs.InternalServerErr(err,
errs.WithKeyVal("serialNumber", oldCert.SerialNumber.String()),
errs.WithMessage("error renewing certificate"),
)
}
resp, err := a.x509CAService.RenewCertificate(&casapi.RenewCertificateRequest{
Template: newCert,
Lifetime: lifetime,
@ -621,6 +633,18 @@ func (a *Authority) GetTLSCertificate() (*tls.Certificate, error) {
certTpl.NotBefore = now.Add(-1 * time.Minute)
certTpl.NotAfter = now.Add(24 * time.Hour)
// Policy and constraints require this fields to be set. At this moment they
// are only present in the extra extension.
certTpl.DNSNames = cr.DNSNames
certTpl.IPAddresses = cr.IPAddresses
certTpl.EmailAddresses = cr.EmailAddresses
certTpl.URIs = cr.URIs
// Fail if name constraints do not allow the server names.
if err := a.constraintsEngine.ValidateCertificate(certTpl); err != nil {
return fatal(err)
}
resp, err := a.x509CAService.CreateCertificate(&casapi.CreateCertificateRequest{
Template: certTpl,
CSR: cr,

View file

@ -22,6 +22,7 @@ import (
"go.step.sm/crypto/jose"
"go.step.sm/crypto/keyutil"
"go.step.sm/crypto/minica"
"go.step.sm/crypto/pemutil"
"go.step.sm/crypto/x509util"
@ -542,7 +543,7 @@ ZYtQ9Ot36qc=
notBefore: signOpts.NotBefore.Time().Truncate(time.Second),
notAfter: signOpts.NotAfter.Time().Truncate(time.Second),
extensionsCount: 6,
err: errors.New("authority not allowed to sign"),
err: errors.New("dns name \"test.smallstep.com\" not allowed"),
code: http.StatusForbidden,
}
},
@ -1589,3 +1590,86 @@ func TestAuthority_Revoke(t *testing.T) {
})
}
}
func TestAuthority_constraints(t *testing.T) {
ca, err := minica.New(
minica.WithIntermediateTemplate(`{
"subject": {{ toJson .Subject }},
"keyUsage": ["certSign", "crlSign"],
"basicConstraints": {
"isCA": true,
"maxPathLen": 0
},
"nameConstraints": {
"critical": true,
"permittedDNSDomains": ["internal.example.org"],
"excludedDNSDomains": ["internal.example.com"],
"permittedIPRanges": ["192.168.1.0/24", "192.168.2.1/32"],
"excludedIPRanges": ["192.168.3.0/24", "192.168.4.0/28"],
"permittedEmailAddresses": ["root@example.org", "example.org", ".acme.org"],
"excludedEmailAddresses": ["root@example.com", "example.com", ".acme.com"],
"permittedURIDomains": ["uuid.example.org", ".acme.org"],
"excludedURIDomains": ["uuid.example.com", ".acme.com"]
}
}`),
)
if err != nil {
t.Fatal(err)
}
auth, err := NewEmbedded(WithX509RootCerts(ca.Root), WithX509Signer(ca.Intermediate, ca.Signer))
if err != nil {
t.Fatal(err)
}
signer, err := keyutil.GenerateDefaultSigner()
if err != nil {
t.Fatal(err)
}
tests := []struct {
name string
sans []string
wantErr bool
}{
{"ok dns", []string{"internal.example.org", "host.internal.example.org"}, false},
{"ok ip", []string{"192.168.1.10", "192.168.2.1"}, false},
{"ok email", []string{"root@example.org", "info@example.org", "info@www.acme.org"}, false},
{"ok uri", []string{"https://uuid.example.org/b908d973-5167-4a62-abe3-6beda358d82a", "https://uuid.acme.org/1724aae1-1bb3-44fb-83c3-9a1a18df67c8"}, false},
{"fail permitted dns", []string{"internal.acme.org"}, true},
{"fail excluded dns", []string{"internal.example.com"}, true},
{"fail permitted ips", []string{"192.168.2.10"}, true},
{"fail excluded ips", []string{"192.168.3.1"}, true},
{"fail permitted emails", []string{"root@acme.org"}, true},
{"fail excluded emails", []string{"root@example.com"}, true},
{"fail permitted uris", []string{"https://acme.org/uuid/7848819c-9d0b-4e12-bbff-cd66079a3444"}, true},
{"fail excluded uris", []string{"https://uuid.example.com/d325eda7-6356-4d60-b8f6-3d64724afeb3"}, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
csr, err := x509util.CreateCertificateRequest(tt.sans[0], tt.sans, signer)
if err != nil {
t.Fatal(err)
}
cert, err := ca.SignCSR(csr)
if err != nil {
t.Fatal(err)
}
data := x509util.CreateTemplateData(tt.sans[0], tt.sans)
templateOption, err := provisioner.TemplateOptions(nil, data)
if err != nil {
t.Fatal(err)
}
_, err = auth.Sign(csr, provisioner.SignOptions{}, templateOption)
if (err != nil) != tt.wantErr {
t.Errorf("Authority.Sign() error = %v, wantErr %v", err, tt.wantErr)
}
_, err = auth.Renew(cert)
if (err != nil) != tt.wantErr {
t.Errorf("Authority.Renew() error = %v, wantErr %v", err, tt.wantErr)
}
})
}
}

View file

@ -4,11 +4,13 @@ import (
"crypto/x509"
"fmt"
"net"
"net/http"
"net/url"
"go.step.sm/crypto/x509util"
"golang.org/x/crypto/ssh"
"go.step.sm/crypto/x509util"
"github.com/smallstep/certificates/errs"
)
type NamePolicyReason int
@ -62,6 +64,22 @@ func (e *NamePolicyError) Error() string {
}
}
// As implements the As(any) bool interface and allows to use "errors.As()" to
// convert a NotAllowed NamePolicyError to an errs.Error.
func (e *NamePolicyError) As(v any) bool {
if e.Reason == NotAllowed {
if err, ok := v.(**errs.Error); ok {
*err = &errs.Error{
Status: http.StatusForbidden,
Msg: fmt.Sprintf("The request was forbidden by the certificate authority: %s", e.Error()),
Err: e,
}
return true
}
}
return false
}
func (e *NamePolicyError) Detail() string {
return e.detail
}