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kubeadm: fix wrong check for keys/certs during "download-certs"

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During "join" of new control plane machines, kubeadm would
download shared certificates and keys from the cluster stored
in a Secret. Based on the contents of an entry in the Secret,
it would use helper functions from client-go to either write
it as public key, cert (mode 644) or as a private key (mode 600).

The existing logic is always writing both keys and certs with mode 600.
Allow detecting public readable data properly and writing some files
with mode 644.

First check the data with ParsePrivateKeyPEM(); if this passes
there must be at least one private key and the file should be written
with mode 600 as private. If that fails, validate if the data contains
public keys with ParsePublicKeysPEM() and write the file as public
(mode 644).

As a result of this new logic, and given the current set of managed
kubeadm files, .key files will end up with 600, while .crt and .pub
files will end up with 644.
This commit is contained in:
Lubomir I. Ivanov 2021-06-29 23:13:32 +03:00
parent 01819dd322
commit 5c00024c70
2 changed files with 4 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
cmd/kubeadm/app/phases/copycerts/copycerts.go
View File

@ -251,9 +251,9 @@ func DownloadCerts(client clientset.Interface, cfg *kubeadmapi.InitConfiguration
}
func writeCertOrKey(certOrKeyPath string, certOrKeyData []byte) error {
if _, err := keyutil.ParsePublicKeysPEM(certOrKeyData); err == nil {
if _, err := keyutil.ParsePrivateKeyPEM(certOrKeyData); err == nil {
return keyutil.WriteKey(certOrKeyPath, certOrKeyData)
} else if _, err := certutil.ParseCertsPEM(certOrKeyData); err == nil {
} else if _, err := keyutil.ParsePublicKeysPEM(certOrKeyData); err == nil {
return certutil.WriteCert(certOrKeyPath, certOrKeyData)
}
return errors.New("unknown data found in Secret entry")

5
cmd/kubeadm/app/phases/copycerts/copycerts_test.go
View File

@ -29,7 +29,6 @@ import (
v1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
fakeclient "k8s.io/client-go/kubernetes/fake"
certutil "k8s.io/client-go/util/cert"
keyutil "k8s.io/client-go/util/keyutil"
kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
@ -240,7 +239,7 @@ func TestDownloadCerts(t *testing.T) {
}
// Check that the written files are either certificates or keys, and that they have
// the expected permissions
if _, err := keyutil.ParsePublicKeysPEM(diskCertData); err == nil {
if _, err := keyutil.ParsePrivateKeyPEM(diskCertData); err == nil {
if stat, err := os.Stat(certPath); err == nil {
if stat.Mode() != keyFileMode {
t.Errorf("key %q should have mode %#o, has %#o", certName, keyFileMode, stat.Mode())
@ -248,7 +247,7 @@ func TestDownloadCerts(t *testing.T) {
} else {
t.Errorf("could not stat key %q: %v", certName, err)
}
} else if _, err := certutil.ParseCertsPEM(diskCertData); err == nil {
} else if _, err := keyutil.ParsePublicKeysPEM(diskCertData); err == nil {
if stat, err := os.Stat(certPath); err == nil {
if stat.Mode() != certFileMode {
t.Errorf("cert %q should have mode %#o, has %#o", certName, certFileMode, stat.Mode())