certificates/authority/internal/constraints/constraints.go
2022-09-20 12:33:03 -07:00

117 lines
3.5 KiB
Go

package constraints
import (
"crypto/x509"
"fmt"
"net"
"net/url"
)
var oidExtensionNameConstraints = []int{2, 5, 29, 30}
// 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
}
// 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 {
s := new(Engine)
for _, crt := range chain {
s.permittedDNSDomains = append(s.permittedDNSDomains, crt.PermittedDNSDomains...)
s.excludedDNSDomains = append(s.excludedDNSDomains, crt.ExcludedDNSDomains...)
s.permittedIPRanges = append(s.permittedIPRanges, crt.PermittedIPRanges...)
s.excludedIPRanges = append(s.excludedIPRanges, crt.ExcludedIPRanges...)
s.permittedEmailAddresses = append(s.permittedEmailAddresses, crt.PermittedEmailAddresses...)
s.excludedEmailAddresses = append(s.excludedEmailAddresses, crt.ExcludedEmailAddresses...)
s.permittedURIDomains = append(s.permittedURIDomains, crt.PermittedURIDomains...)
s.excludedURIDomains = append(s.excludedURIDomains, crt.ExcludedURIDomains...)
if !s.hasNameConstraints {
for _, ext := range crt.Extensions {
if ext.Id.Equal(oidExtensionNameConstraints) {
s.hasNameConstraints = true
break
}
}
}
}
return s
}
// Validate checks the given names with the name constraints defined in the
// service.
func (s *Engine) Validate(dnsNames []string, ipAddresses []net.IP, emailAddresses []string, uris []*url.URL) error {
if s == nil || !s.hasNameConstraints {
return nil
}
for _, name := range dnsNames {
if err := checkNameConstraints("DNS name", name, name, s.permittedDNSDomains, s.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, s.permittedIPRanges, s.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, s.permittedEmailAddresses, s.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, s.permittedURIDomains, s.excludedURIDomains,
func(parsedName, constraint any) (bool, error) {
return matchURIConstraint(parsedName.(*url.URL), constraint.(string))
},
); err != nil {
return err
}
}
return nil
}