/*
ValidateRoot receives a new root, validates its correctness and attempts to
do root key rotation if needed.
First we list the current trusted certificates we have for a particular GUN. If
that list is non-empty means that we've already seen this repository before, and
have a list of trusted certificates for it. In this case, we use this list of
certificates to attempt to validate this root file.
If the previous validation succeeds, or in the case where we found no trusted
certificates for this particular GUN, we check the integrity of the root by
making sure that it is validated by itself. This means that we will attempt to
validate the root data with the certificates that are included in the root keys
themselves.
If this last steps succeeds, we attempt to do root rotation, by ensuring that
we only trust the certificates that are present in the new root.
This mechanism of operation is essentially Trust On First Use (TOFU): if we
have never seen a certificate for a particular CN, we trust it. If later we see
a different certificate for that certificate, we return an ErrValidationFailed error.
Note that since we only allow trust data to be downloaded over an HTTPS channel
we are using the current public PKI to validate the first download of the certificate
adding an extra layer of security over the normal (SSH style) trust model.
We shall call this: TOFUS.
*/
func ValidateRoot(certStore trustmanager.X509Store, root *data.Signed, gun string) error {
logrus.Debugf("entered ValidateRoot with dns: %s", gun)
signedRoot, err := data.RootFromSigned(root)
if err != nil {
return err
}
// Retrieve all the leaf certificates in root for which the CN matches the GUN
allValidCerts, err := validRootLeafCerts(signedRoot, gun)
if err != nil {
logrus.Debugf("error retrieving valid leaf certificates for: %s, %v", gun, err)
return &ErrValidationFail{Reason: "unable to retrieve valid leaf certificates"}
}
// Retrieve all the trusted certificates that match this gun
certsForCN, err := certStore.GetCertificatesByCN(gun)
if err != nil {
// If the error that we get back is different than ErrNoCertificatesFound
// we couldn't check if there are any certificates with this CN already
// trusted. Let's take the conservative approach and return a failed validation
if _, ok := err.(*trustmanager.ErrNoCertificatesFound); !ok {
logrus.Debugf("error retrieving trusted certificates for: %s, %v", gun, err)
return &ErrValidationFail{Reason: "unable to retrieve trusted certificates"}
}
}
// If we have certificates that match this specific GUN, let's make sure to
// use them first to validate that this new root is valid.
if len(certsForCN) != 0 {
logrus.Debugf("found %d valid root certificates for %s", len(certsForCN), gun)
err = signed.VerifyRoot(root, 0, trustmanager.CertsToKeys(certsForCN))
if err != nil {
logrus.Debugf("failed to verify TUF data for: %s, %v", gun, err)
return &ErrValidationFail{Reason: "failed to validate data with current trusted certificates"}
}
} else {
logrus.Debugf("found no currently valid root certificates for %s", gun)
}
// Validate the integrity of the new root (does it have valid signatures)
err = signed.VerifyRoot(root, 0, trustmanager.CertsToKeys(allValidCerts))
if err != nil {
logrus.Debugf("failed to verify TUF data for: %s, %v", gun, err)
return &ErrValidationFail{Reason: "failed to validate integrity of roots"}
}
// Getting here means A) we had trusted certificates and both the
// old and new validated this root; or B) we had no trusted certificates but
// the new set of certificates has integrity (self-signed)
logrus.Debugf("entering root certificate rotation for: %s", gun)
// Do root certificate rotation: we trust only the certs present in the new root
// First we add all the new certificates (even if they already exist)
for _, cert := range allValidCerts {
err := certStore.AddCert(cert)
if err != nil {
// If the error is already exists we don't fail the rotation
if _, ok := err.(*trustmanager.ErrCertExists); ok {
logrus.Debugf("ignoring certificate addition to: %s", gun)
continue
}
logrus.Debugf("error adding new trusted certificate for: %s, %v", gun, err)
}
}
// Now we delete old certificates that aren't present in the new root
for certID, cert := range certsToRemove(certsForCN, allValidCerts) {
logrus.Debugf("removing certificate with certID: %s", certID)
err = certStore.RemoveCert(cert)
if err != nil {
logrus.Debugf("failed to remove trusted certificate with keyID: %s, %v", certID, err)
return &ErrRootRotationFail{Reason: "failed to rotate root keys"}
}
}
logrus.Debugf("Root validation succeeded for %s", gun)
return nil
}
/*
ValidateRoot receives a new root, validates its correctness and attempts to
do root key rotation if needed.
First we list the current trusted certificates we have for a particular GUN. If
that list is non-empty means that we've already seen this repository before, and
have a list of trusted certificates for it. In this case, we use this list of
certificates to attempt to validate this root file.
If the previous validation succeeds, we check the integrity of the root by
making sure that it is validated by itself. This means that we will attempt to
validate the root data with the certificates that are included in the root keys
themselves.
However, if we do not have any current trusted certificates for this GUN, we
check if there are any pinned certificates specified in the trust_pinning section
of the notary client config. If this section specifies a Certs section with this
GUN, we attempt to validate that the certificates present in the downloaded root
file match the pinned ID.
If the Certs section is empty for this GUN, we check if the trust_pinning
section specifies a CA section specified in the config for this GUN. If so, we check
that the specified CA is valid and has signed a certificate included in the downloaded
root file. The specified CA can be a prefix for this GUN.
If both the Certs and CA configs do not match this GUN, we fall back to the TOFU
section in the config: if true, we trust certificates specified in the root for
this GUN. If later we see a different certificate for that certificate, we return
an ErrValidationFailed error.
Note that since we only allow trust data to be downloaded over an HTTPS channel
we are using the current public PKI to validate the first download of the certificate
adding an extra layer of security over the normal (SSH style) trust model.
We shall call this: TOFUS.
Validation failure at any step will result in an ErrValidationFailed error.
*/
func ValidateRoot(certStore trustmanager.X509Store, root *data.Signed, gun string, trustPinning TrustPinConfig) error {
logrus.Debugf("entered ValidateRoot with dns: %s", gun)
signedRoot, err := data.RootFromSigned(root)
if err != nil {
return err
}
rootRole, err := signedRoot.BuildBaseRole(data.CanonicalRootRole)
if err != nil {
return err
}
// Retrieve all the leaf and intermediate certificates in root for which the CN matches the GUN
allLeafCerts, allIntCerts := parseAllCerts(signedRoot)
certsFromRoot, err := validRootLeafCerts(allLeafCerts, gun)
if err != nil {
logrus.Debugf("error retrieving valid leaf certificates for: %s, %v", gun, err)
return &ErrValidationFail{Reason: "unable to retrieve valid leaf certificates"}
}
// Retrieve all the trusted certificates that match this gun
trustedCerts, err := certStore.GetCertificatesByCN(gun)
if err != nil {
// If the error that we get back is different than ErrNoCertificatesFound
// we couldn't check if there are any certificates with this CN already
// trusted. Let's take the conservative approach and return a failed validation
if _, ok := err.(*trustmanager.ErrNoCertificatesFound); !ok {
logrus.Debugf("error retrieving trusted certificates for: %s, %v", gun, err)
return &ErrValidationFail{Reason: "unable to retrieve trusted certificates"}
}
}
// If we have certificates that match this specific GUN, let's make sure to
// use them first to validate that this new root is valid.
if len(trustedCerts) != 0 {
logrus.Debugf("found %d valid root certificates for %s: %s", len(trustedCerts), gun,
prettyFormatCertIDs(trustedCerts))
err = signed.VerifySignatures(
root, data.BaseRole{Keys: trustmanager.CertsToKeys(trustedCerts, allIntCerts), Threshold: 1})
if err != nil {
logrus.Debugf("failed to verify TUF data for: %s, %v", gun, err)
return &ErrValidationFail{Reason: "failed to validate data with current trusted certificates"}
}
} else {
logrus.Debugf("found no currently valid root certificates for %s, using trust_pinning config to bootstrap trust", gun)
trustPinCheckFunc, err := NewTrustPinChecker(trustPinning, gun)
if err != nil {
return &ErrValidationFail{Reason: err.Error()}
}
validPinnedCerts := []*x509.Certificate{}
for _, cert := range certsFromRoot {
certID, err := trustmanager.FingerprintCert(cert)
if err != nil {
continue
}
if ok := trustPinCheckFunc(cert, allIntCerts[certID]); !ok {
continue
}
validPinnedCerts = append(validPinnedCerts, cert)
}
if len(validPinnedCerts) == 0 {
return &ErrValidationFail{Reason: "unable to match any certificates to trust_pinning config"}
}
certsFromRoot = validPinnedCerts
}
// Validate the integrity of the new root (does it have valid signatures)
// Note that certsFromRoot is guaranteed to be unchanged only if we had prior cert data for this GUN or enabled TOFUS
// If we attempted to pin a certain certificate or CA, certsFromRoot could have been pruned accordingly
err = signed.VerifySignatures(root, data.BaseRole{
Keys: trustmanager.CertsToKeys(certsFromRoot, allIntCerts), Threshold: rootRole.Threshold})
if err != nil {
logrus.Debugf("failed to verify TUF data for: %s, %v", gun, err)
return &ErrValidationFail{Reason: "failed to validate integrity of roots"}
}
// Getting here means:
// A) we had trusted certificates and both the old and new validated this root.
// or
// B) we had no trusted certificates but the new set of certificates has integrity (self-signed).
logrus.Debugf("entering root certificate rotation for: %s", gun)
// Do root certificate rotation: we trust only the certs present in the new root
// First we add all the new certificates (even if they already exist)
for _, cert := range certsFromRoot {
err := certStore.AddCert(cert)
if err != nil {
// If the error is already exists we don't fail the rotation
if _, ok := err.(*trustmanager.ErrCertExists); ok {
logrus.Debugf("ignoring certificate addition to: %s", gun)
continue
}
logrus.Debugf("error adding new trusted certificate for: %s, %v", gun, err)
}
}
// Now we delete old certificates that aren't present in the new root
oldCertsToRemove, err := certsToRemove(trustedCerts, certsFromRoot)
if err != nil {
logrus.Debugf("inconsistency when removing old certificates: %v", err)
return err
}
for certID, cert := range oldCertsToRemove {
logrus.Debugf("removing certificate with certID: %s", certID)
err = certStore.RemoveCert(cert)
if err != nil {
logrus.Debugf("failed to remove trusted certificate with keyID: %s, %v", certID, err)
return &ErrRootRotationFail{Reason: "failed to rotate root keys"}
}
}
logrus.Debugf("Root validation succeeded for %s", gun)
return nil
}