Mariano Cano
2 years ago
parent
fcb9d88223
commit
0263468424
@ -0,0 +1,106 @@
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package constraints
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import (
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"crypto/x509"
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"fmt"
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"net"
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"net/url"
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)
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var oidExtensionNameConstraints = []int{2, 5, 29, 30}
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type ConstraintError struct {
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Type string
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Name string
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}
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func (e ConstraintError) Error() string {
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return fmt.Sprintf("%s %q is not allowed", e.Type, e.Name)
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}
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type service struct {
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hasNameConstraints bool
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permittedDNSDomains []string
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excludedDNSDomains []string
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permittedIPRanges []*net.IPNet
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excludedIPRanges []*net.IPNet
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permittedEmailAddresses []string
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excludedEmailAddresses []string
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permittedURIDomains []string
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excludedURIDomains []string
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}
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func New(chain ...*x509.Certificate) *service {
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s := new(service)
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for _, crt := range chain {
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s.permittedDNSDomains = append(s.permittedDNSDomains, crt.PermittedDNSDomains...)
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s.excludedDNSDomains = append(s.excludedDNSDomains, crt.ExcludedDNSDomains...)
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s.permittedIPRanges = append(s.permittedIPRanges, crt.PermittedIPRanges...)
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s.excludedIPRanges = append(s.excludedIPRanges, crt.ExcludedIPRanges...)
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s.permittedEmailAddresses = append(s.permittedEmailAddresses, crt.PermittedEmailAddresses...)
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s.excludedEmailAddresses = append(s.excludedEmailAddresses, crt.ExcludedEmailAddresses...)
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s.permittedURIDomains = append(s.permittedURIDomains, crt.PermittedURIDomains...)
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s.excludedURIDomains = append(s.excludedURIDomains, crt.ExcludedURIDomains...)
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if !s.hasNameConstraints {
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for _, ext := range crt.Extensions {
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if ext.Id.Equal(oidExtensionNameConstraints) {
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s.hasNameConstraints = true
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break
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}
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}
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}
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}
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return s
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}
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// Validates
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func (s *service) Validate(dnsNames []string, ipAddresses []*net.IP, emailAddresses []string, uris []*url.URL) error {
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if !s.hasNameConstraints {
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return nil
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}
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for _, name := range dnsNames {
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if err := checkNameConstraints("DNS name", name, name, s.permittedDNSDomains, s.excludedDNSDomains,
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func(parsedName, constraint any) (bool, error) {
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return matchDomainConstraint(parsedName.(string), constraint.(string))
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},
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); err != nil {
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return err
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}
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}
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for _, ip := range ipAddresses {
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if err := checkNameConstraints("IP address", ip.String(), ip, s.permittedIPRanges, s.excludedIPRanges,
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func(parsedName, constraint any) (bool, error) {
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return matchIPConstraint(parsedName.(net.IP), constraint.(*net.IPNet))
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}); err != nil {
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return err
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}
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}
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for _, email := range emailAddresses {
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mailbox, ok := parseRFC2821Mailbox(email)
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if !ok {
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return fmt.Errorf("cannot parse rfc822Name %q", email)
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}
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if err := checkNameConstraints("Email address", email, mailbox, s.permittedEmailAddresses, s.excludedEmailAddresses,
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func(parsedName, constraint any) (bool, error) {
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return matchEmailConstraint(parsedName.(rfc2821Mailbox), constraint.(string))
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},
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); err != nil {
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return err
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}
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}
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for _, uri := range uris {
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if err := checkNameConstraints("URI", uri.String(), uri, s.permittedURIDomains, s.excludedURIDomains,
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func(parsedName, constraint any) (bool, error) {
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return matchURIConstraint(parsedName.(*url.URL), constraint.(string))
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}); err != nil {
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return err
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}
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}
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return nil
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}
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@ -0,0 +1,140 @@
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package constraints
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import (
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"crypto/x509"
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"net"
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"net/url"
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"reflect"
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"testing"
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"go.step.sm/crypto/minica"
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)
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func TestNew(t *testing.T) {
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ca1, err := minica.New()
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if err != nil {
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t.Fatal(err)
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}
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ca2, err := minica.New(
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minica.WithIntermediateTemplate(`{
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"subject": {{ toJson .Subject }},
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"keyUsage": ["certSign", "crlSign"],
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"basicConstraints": {
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"isCA": true,
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"maxPathLen": 0
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},
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"nameConstraints": {
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"critical": true,
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"permittedDNSDomains": ["internal.example.org"],
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"excludedDNSDomains": ["internal.example.com"],
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"permittedIPRanges": ["192.168.1.0/24", "192.168.2.1/32"],
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"excludedIPRanges": ["192.168.3.0/24", "192.168.4.0/28"],
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"permittedEmailAddresses": ["root@example.org", "example.org", ".acme.org"],
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"excludedEmailAddresses": ["root@example.com", "example.com", ".acme.com"],
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"permittedURIDomains": ["host.example.org", ".acme.org"],
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"excludedURIDomains": ["host.example.com", ".acme.com"]
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}
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}`),
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)
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if err != nil {
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t.Fatal(err)
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}
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type args struct {
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chain []*x509.Certificate
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}
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tests := []struct {
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name string
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args args
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want *service
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}{
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{"ok", args{[]*x509.Certificate{ca1.Intermediate, ca1.Root}}, &service{
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hasNameConstraints: false,
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}},
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{"ok with constraints", args{[]*x509.Certificate{ca2.Intermediate, ca2.Root}}, &service{
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hasNameConstraints: true,
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permittedDNSDomains: []string{"internal.example.org"},
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excludedDNSDomains: []string{"internal.example.com"},
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permittedIPRanges: []*net.IPNet{
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{IP: net.ParseIP("192.168.1.0").To4(), Mask: net.IPMask{255, 255, 255, 0}},
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{IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}},
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},
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excludedIPRanges: []*net.IPNet{
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{IP: net.ParseIP("192.168.3.0").To4(), Mask: net.IPMask{255, 255, 255, 0}},
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{IP: net.ParseIP("192.168.4.0").To4(), Mask: net.IPMask{255, 255, 255, 240}},
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},
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permittedEmailAddresses: []string{"root@example.org", "example.org", ".acme.org"},
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excludedEmailAddresses: []string{"root@example.com", "example.com", ".acme.com"},
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permittedURIDomains: []string{"host.example.org", ".acme.org"},
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excludedURIDomains: []string{"host.example.com", ".acme.com"},
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}},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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if got := New(tt.args.chain...); !reflect.DeepEqual(got, tt.want) {
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t.Errorf("New() = %v, want %v", got, tt.want)
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}
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})
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}
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}
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func Test_service_Validate(t *testing.T) {
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type fields struct {
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hasNameConstraints bool
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permittedDNSDomains []string
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excludedDNSDomains []string
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permittedIPRanges []*net.IPNet
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excludedIPRanges []*net.IPNet
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permittedEmailAddresses []string
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excludedEmailAddresses []string
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permittedURIDomains []string
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excludedURIDomains []string
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}
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type args struct {
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dnsNames []string
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ipAddresses []*net.IP
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emailAddresses []string
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uris []*url.URL
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}
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tests := []struct {
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name string
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fields fields
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args args
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wantErr bool
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}{
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{"ok", fields{hasNameConstraints: false}, args{
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dnsNames: []string{"example.com", "host.example.com"},
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ipAddresses: []*net.IP{{192, 168, 1, 1}, {0x26, 0x00, 0x1f, 0x1c, 0x47, 0x1, 0x9d, 0x00, 0xc3, 0xa7, 0x66, 0x94, 0x87, 0x0f, 0x20, 0x72}},
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emailAddresses: []string{"root@example.com"},
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uris: []*url.URL{{Scheme: "https", Host: "example.com", Path: "/uuid/c6d1a755-0c12-431e-9136-b64cb3173ec7"}},
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}, false},
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// {"ok dns", fields{}, args{}, false},
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// {"ok ip", fields{}, args{}, false},
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// {"ok email", fields{}, args{}, false},
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// {"ok uri", fields{}, args{}, false},
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// {"fail dns", fields{}, args{}, true},
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// {"fail ip", fields{}, args{}, true},
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// {"fail email", fields{}, args{}, true},
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// {"fail uri", fields{}, args{}, true},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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s := &service{
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hasNameConstraints: tt.fields.hasNameConstraints,
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permittedDNSDomains: tt.fields.permittedDNSDomains,
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excludedDNSDomains: tt.fields.excludedDNSDomains,
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permittedIPRanges: tt.fields.permittedIPRanges,
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excludedIPRanges: tt.fields.excludedIPRanges,
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permittedEmailAddresses: tt.fields.permittedEmailAddresses,
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excludedEmailAddresses: tt.fields.excludedEmailAddresses,
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permittedURIDomains: tt.fields.permittedURIDomains,
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excludedURIDomains: tt.fields.excludedURIDomains,
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}
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if err := s.Validate(tt.args.dnsNames, tt.args.ipAddresses, tt.args.emailAddresses, tt.args.uris); (err != nil) != tt.wantErr {
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t.Errorf("service.Validate() error = %v, wantErr %v", err, tt.wantErr)
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}
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})
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}
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}
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@ -0,0 +1,358 @@
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// Copyright (c) 2009 The Go Authors. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package constraints
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import (
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"bytes"
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"fmt"
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"net"
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"net/url"
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"reflect"
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"strings"
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)
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func checkNameConstraints(nameType string, name string, parsedName any, permitted, excluded any, match func(name, constraint any) (bool, error)) error {
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excludedValue := reflect.ValueOf(excluded)
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for i := 0; i < excludedValue.Len(); i++ {
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constraint := excludedValue.Index(i).Interface()
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match, err := match(parsedName, constraint)
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if err != nil {
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return err
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}
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if match {
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return fmt.Errorf("%s %q is excluded by constraint %q", nameType, name, constraint)
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}
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}
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var (
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err error
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ok = true
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)
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permittedValue := reflect.ValueOf(permitted)
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for i := 0; i < permittedValue.Len(); i++ {
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constraint := permittedValue.Index(i).Interface()
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if ok, err = match(parsedName, constraint); err != nil {
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return err
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}
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if ok {
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break
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}
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}
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if !ok {
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return fmt.Errorf("%s %q is not permitted by any constraint", nameType, name)
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}
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return nil
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}
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func matchDomainConstraint(domain, constraint string) (bool, error) {
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// The meaning of zero length constraints is not specified, but this
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// code follows NSS and accepts them as matching everything.
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if len(constraint) == 0 {
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return true, nil
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}
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domainLabels, ok := domainToReverseLabels(domain)
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if !ok {
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return false, fmt.Errorf("x509: internal error: cannot parse domain %q", domain)
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}
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// RFC 5280 says that a leading period in a domain name means that at
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// least one label must be prepended, but only for URI and email
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// constraints, not DNS constraints. The code also supports that
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// behaviour for DNS constraints.
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mustHaveSubdomains := false
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if constraint[0] == '.' {
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mustHaveSubdomains = true
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constraint = constraint[1:]
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}
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constraintLabels, ok := domainToReverseLabels(constraint)
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if !ok {
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return false, fmt.Errorf("x509: internal error: cannot parse domain %q", constraint)
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}
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if len(domainLabels) < len(constraintLabels) ||
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(mustHaveSubdomains && len(domainLabels) == len(constraintLabels)) {
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return false, nil
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}
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for i, constraintLabel := range constraintLabels {
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if !strings.EqualFold(constraintLabel, domainLabels[i]) {
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return false, nil
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}
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}
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return true, nil
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}
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func matchIPConstraint(ip net.IP, constraint *net.IPNet) (bool, error) {
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if len(ip) != len(constraint.IP) {
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return false, nil
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}
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for i := range ip {
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if mask := constraint.Mask[i]; ip[i]&mask != constraint.IP[i]&mask {
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return false, nil
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}
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}
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return true, nil
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}
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func matchEmailConstraint(mailbox rfc2821Mailbox, constraint string) (bool, error) {
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// If the constraint contains an @, then it specifies an exact mailbox
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// name.
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if strings.Contains(constraint, "@") {
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constraintMailbox, ok := parseRFC2821Mailbox(constraint)
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if !ok {
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return false, fmt.Errorf("x509: internal error: cannot parse constraint %q", constraint)
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}
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return mailbox.local == constraintMailbox.local && strings.EqualFold(mailbox.domain, constraintMailbox.domain), nil
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}
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// Otherwise the constraint is like a DNS constraint of the domain part
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// of the mailbox.
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return matchDomainConstraint(mailbox.domain, constraint)
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}
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func matchURIConstraint(uri *url.URL, constraint string) (bool, error) {
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// From RFC 5280, Section 4.2.1.10:
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// “a uniformResourceIdentifier that does not include an authority
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// component with a host name specified as a fully qualified domain
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// name (e.g., if the URI either does not include an authority
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// component or includes an authority component in which the host name
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// is specified as an IP address), then the application MUST reject the
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// certificate.”
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host := uri.Host
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if len(host) == 0 {
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return false, fmt.Errorf("URI with empty host (%q) cannot be matched against constraints", uri.String())
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}
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if strings.Contains(host, ":") && !strings.HasSuffix(host, "]") {
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var err error
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host, _, err = net.SplitHostPort(uri.Host)
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if err != nil {
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return false, err
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}
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}
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if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") ||
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net.ParseIP(host) != nil {
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return false, fmt.Errorf("URI with IP (%q) cannot be matched against constraints", uri.String())
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}
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return matchDomainConstraint(host, constraint)
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}
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// domainToReverseLabels converts a textual domain name like foo.example.com to
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// the list of labels in reverse order, e.g. ["com", "example", "foo"].
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func domainToReverseLabels(domain string) (reverseLabels []string, ok bool) {
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for len(domain) > 0 {
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if i := strings.LastIndexByte(domain, '.'); i == -1 {
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reverseLabels = append(reverseLabels, domain)
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domain = ""
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} else {
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reverseLabels = append(reverseLabels, domain[i+1:])
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domain = domain[:i]
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}
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}
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if len(reverseLabels) > 0 && len(reverseLabels[0]) == 0 {
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// An empty label at the end indicates an absolute value.
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return nil, false
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}
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for _, label := range reverseLabels {
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if len(label) == 0 {
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// Empty labels are otherwise invalid.
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return nil, false
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}
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for _, c := range label {
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if c < 33 || c > 126 {
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// Invalid character.
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return nil, false
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}
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}
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}
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return reverseLabels, true
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}
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// rfc2821Mailbox represents a “mailbox” (which is an email address to most
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// people) by breaking it into the “local” (i.e. before the '@') and “domain”
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// parts.
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type rfc2821Mailbox struct {
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local, domain string
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}
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// 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 len(in) == 0 {
|
||||
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 len(in) == 0 {
|
||||
return mailbox, false
|
||||
}
|
||||
c := in[0]
|
||||
in = in[1:]
|
||||
|
||||
switch {
|
||||
case c == '"':
|
||||
break QuotedString
|
||||
|
||||
case c == '\\':
|
||||
// quoted-pair
|
||||
if len(in) == 0 {
|
||||
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 len(in) == 0 {
|
||||
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 len(in) == 0 || 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
|
||||
}
|
||||
Loading…
Reference in New Issue