mirror of https://github.com/docker/docs.git
119 lines
4.0 KiB
Go
119 lines
4.0 KiB
Go
package trustpinning
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import (
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"crypto/x509"
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"fmt"
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"github.com/docker/notary/trustmanager"
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"github.com/docker/notary/tuf/utils"
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"strings"
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)
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// TrustPinConfig represents the configuration under the trust_pinning section of the config file
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// This struct represents the preferred way to bootstrap trust for this repository
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type TrustPinConfig struct {
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CA map[string]string
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Certs map[string][]string
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DisableTOFU bool
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}
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type trustPinChecker struct {
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gun string
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config TrustPinConfig
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pinnedCAPool *x509.CertPool
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pinnedCertIDs []string
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}
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// CertChecker is a function type that will be used to check leaf certs against pinned trust
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type CertChecker func(leafCert *x509.Certificate, intCerts []*x509.Certificate) bool
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// NewTrustPinChecker returns a new certChecker function from a TrustPinConfig for a GUN
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func NewTrustPinChecker(trustPinConfig TrustPinConfig, gun string) (CertChecker, error) {
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t := trustPinChecker{gun: gun, config: trustPinConfig}
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// Determine the mode, and if it's even valid
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if pinnedCerts, ok := trustPinConfig.Certs[gun]; ok {
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t.pinnedCertIDs = pinnedCerts
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return t.certsCheck, nil
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}
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if caFilepath, err := getPinnedCAFilepathByPrefix(gun, trustPinConfig); err == nil {
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// Try to add the CA certs from its bundle file to our certificate store,
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// and use it to validate certs in the root.json later
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caCerts, err := trustmanager.LoadCertBundleFromFile(caFilepath)
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if err != nil {
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return nil, fmt.Errorf("could not load root cert from CA path")
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}
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// Now only consider certificates that are direct children from this CA cert chain
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caRootPool := x509.NewCertPool()
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for _, caCert := range caCerts {
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if err = trustmanager.ValidateCertificate(caCert); err != nil {
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continue
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}
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caRootPool.AddCert(caCert)
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}
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// If we didn't have any valid CA certs, error out
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if len(caRootPool.Subjects()) == 0 {
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return nil, fmt.Errorf("invalid CA certs provided")
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}
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t.pinnedCAPool = caRootPool
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return t.caCheck, nil
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}
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if !trustPinConfig.DisableTOFU {
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return t.tofusCheck, nil
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}
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return nil, fmt.Errorf("invalid trust pinning specified")
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}
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func (t trustPinChecker) certsCheck(leafCert *x509.Certificate, intCerts []*x509.Certificate) bool {
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// reconstruct the leaf + intermediate cert chain, which is bundled as {leaf, intermediates...},
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// in order to get the matching id in the root file
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leafCertID, err := trustmanager.FingerprintCert(leafCert)
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if err != nil {
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return false
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}
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rootKeys := trustmanager.CertsToKeys([]*x509.Certificate{leafCert}, map[string][]*x509.Certificate{leafCertID: intCerts})
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for keyID := range rootKeys {
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if utils.StrSliceContains(t.pinnedCertIDs, keyID) {
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return true
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}
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}
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return false
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}
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func (t trustPinChecker) caCheck(leafCert *x509.Certificate, intCerts []*x509.Certificate) bool {
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// Use intermediate certificates included in the root TUF metadata for our validation
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caIntPool := x509.NewCertPool()
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for _, intCert := range intCerts {
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caIntPool.AddCert(intCert)
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}
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// Attempt to find a valid certificate chain from the leaf cert to CA root
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// Use this certificate if such a valid chain exists (possibly using intermediates)
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if _, err := leafCert.Verify(x509.VerifyOptions{Roots: t.pinnedCAPool, Intermediates: caIntPool}); err == nil {
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return true
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}
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return false
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}
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func (t trustPinChecker) tofusCheck(leafCert *x509.Certificate, intCerts []*x509.Certificate) bool {
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return true
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}
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// Will return the CA filepath corresponding to the most specific (longest) entry in the map that is still a prefix
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// of the provided gun. Returns an error if no entry matches this GUN as a prefix.
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func getPinnedCAFilepathByPrefix(gun string, t TrustPinConfig) (string, error) {
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specificGUN := ""
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specificCAFilepath := ""
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foundCA := false
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for gunPrefix, caFilepath := range t.CA {
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if strings.HasPrefix(gun, gunPrefix) && len(gunPrefix) >= len(specificGUN) {
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specificGUN = gunPrefix
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specificCAFilepath = caFilepath
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foundCA = true
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}
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}
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if !foundCA {
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return "", fmt.Errorf("could not find pinned CA for GUN: %s\n", gun)
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}
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return specificCAFilepath, nil
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}
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