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secrets.go
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secrets.go
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package secrets
import (
"encoding/json"
"errors"
"fmt"
"io"
"io/fs"
"path/filepath"
)
const (
// SimpleType secrets are basic string secrets.
SimpleType = "simple"
// VersionedType secrets are secrets that can be rotated gracefully.
VersionedType = "versioned"
// CredentialType secrets are username/password pairs as a single secret
// in vault.
CredentialType = "credential"
)
// A Secret is the base type of secrets.
type Secret []byte
// IsEmpty returns true if the secret is empty.
func (s Secret) IsEmpty() bool {
return len(s) == 0
}
// CSIFile represents the raw parsed object of a file made by the Vault CSI provider
type CSIFile struct {
Secret GenericSecret `json:"data"`
}
// Secrets allows to access secrets based on their different type.
type Secrets struct {
simpleSecrets map[string]SimpleSecret
versionedSecrets map[string]VersionedSecret
credentialSecrets map[string]CredentialSecret
vault Vault
}
// GetSimpleSecret fetches a simple secret or error if the key is not present.
func (s *Secrets) GetSimpleSecret(path string) (SimpleSecret, error) {
if path == "" {
return SimpleSecret{}, ErrEmptySecretKey
}
secret, ok := s.simpleSecrets[path]
if !ok {
_, ok := s.versionedSecrets[path]
if ok {
return secret, SecretWrongTypeError{
Path: path,
DeclaredType: SimpleType,
CorrectType: VersionedType,
}
}
_, ok = s.credentialSecrets[path]
if ok {
return secret, SecretWrongTypeError{
Path: path,
DeclaredType: SimpleType,
CorrectType: CredentialType,
}
}
return secret, SecretNotFoundError(path)
}
return secret, nil
}
// GetVersionedSecret fetches a versioned secret or error if the key is not present.
func (s *Secrets) GetVersionedSecret(path string) (VersionedSecret, error) {
if path == "" {
return VersionedSecret{}, ErrEmptySecretKey
}
secret, ok := s.versionedSecrets[path]
if !ok {
_, ok := s.simpleSecrets[path]
if ok {
return secret, SecretWrongTypeError{
Path: path,
DeclaredType: VersionedType,
CorrectType: SimpleType,
}
}
_, ok = s.credentialSecrets[path]
if ok {
return secret, SecretWrongTypeError{
Path: path,
DeclaredType: VersionedType,
CorrectType: CredentialType,
}
}
return secret, SecretNotFoundError(path)
}
return secret, nil
}
// GetCredentialSecret fetches a credential secret or error if the key is not
// present.
func (s *Secrets) GetCredentialSecret(path string) (CredentialSecret, error) {
if path == "" {
return CredentialSecret{}, ErrEmptySecretKey
}
secret, ok := s.credentialSecrets[path]
if !ok {
_, ok := s.simpleSecrets[path]
if ok {
return secret, SecretWrongTypeError{
Path: path,
DeclaredType: CredentialType,
CorrectType: SimpleType,
}
}
_, ok = s.versionedSecrets[path]
if ok {
return secret, SecretWrongTypeError{
Path: path,
DeclaredType: CredentialType,
CorrectType: VersionedType,
}
}
return secret, SecretNotFoundError(path)
}
return secret, nil
}
// SimpleSecret represent basic secrets.
type SimpleSecret struct {
Value Secret
}
// Returns a new instance of SimpleSecret based on a
// GenericSecret from Document. If there is an encoding specified the
// raw secret will be decoded prior.
func newSimpleSecret(secret *GenericSecret) (SimpleSecret, error) {
var result SimpleSecret
value, err := secret.Encoding.decodeValue(secret.Value)
if err != nil {
return result, err
}
return SimpleSecret{
Value: value,
}, nil
}
// AsVersioned returns the SimpleSecret as a VersionedSecret.
//
// The Value of the SimpleSecret will be set as the Current value on the
// VersionedSecret.
func (s SimpleSecret) AsVersioned() VersionedSecret {
return VersionedSecret{Current: s.Value}
}
// VersionedSecret represent secrets like signing keys that can be rotated
// gracefully.
//
// The current property contains the active version of a secret. This should be
// used for any actions that generate new cryptographic data (e.g. signing a
// token).
//
// The previous and next fields contain old and not-yet-active versions of the
// secret respectively. These MAY be used by applications to give a grace
// period for cryptographic tokens generated during a rotation, but SHOULD NOT
// be used to generate new cryptographic tokens.
type VersionedSecret struct {
Current Secret
Previous Secret
Next Secret
}
// Returns a new instance of VersionedSecret based on a
// GenericSecret from Document. If there is an encoding specified the
// raw secrets will be decoded prior.
func newVersionedSecret(secret *GenericSecret) (VersionedSecret, error) {
var result VersionedSecret
current := secret.Current
previous := secret.Previous
next := secret.Next
currentSecret, err := secret.Encoding.decodeValue(current)
if err != nil {
return result, err
}
previousSecret, err := secret.Encoding.decodeValue(previous)
if err != nil {
return result, err
}
nextSecret, err := secret.Encoding.decodeValue(next)
if err != nil {
return result, err
}
return VersionedSecret{
Current: currentSecret,
Previous: previousSecret,
Next: nextSecret,
}, nil
}
// GetAll returns all versions that are not empty in the following order:
// current, previous, next.
func (v *VersionedSecret) GetAll() []Secret {
allVersions := []Secret{v.Current}
if !v.Previous.IsEmpty() {
allVersions = append(allVersions, v.Previous)
}
if !v.Next.IsEmpty() {
allVersions = append(allVersions, v.Next)
}
return allVersions
}
// CredentialSecret represent represent username/password pairs as a single
// secret in vault. Note that usernames are not generally considered secret,
// but they are tied to passwords.
type CredentialSecret struct {
Username string
Password string
}
// NewCredentialSecret returns a new instance of CredentialSecret based on a
// GenericSecret from Document.
func newCredentialSecret(secret *GenericSecret) (CredentialSecret, error) {
return CredentialSecret{
Username: secret.Username,
Password: secret.Password,
}, nil
}
// Document represents the raw parsed entity of a Secrets JSON and is
// not meant to be used other than instantiating Secrets.
type Document struct {
Secrets map[string]GenericSecret `json:"secrets"`
Vault Vault `json:"vault"`
}
// Validate checks the Document for any errors that violate the Baseplate
// specification.
//
// When this function returns a non-nil error, the error is either a
// TooManyFieldsError, or a BatchError containing multiple TooManyFieldsError.
func (s *Document) Validate() error {
errs := make([]error, 0, len(s.Secrets))
for key, value := range s.Secrets {
if value.Type == SimpleType && notOnlySimpleSecret(value) {
errs = append(errs, TooManyFieldsError{
SecretType: SimpleType,
Key: key,
})
}
if value.Type == VersionedType && notOnlyVersionedSecret(value) {
errs = append(errs, TooManyFieldsError{
SecretType: VersionedType,
Key: key,
})
}
if value.Type == CredentialType && notOnlyCredentialSecret(value) {
errs = append(errs, TooManyFieldsError{
SecretType: CredentialType,
Key: key,
})
}
}
return errors.Join(errs...)
}
func notOnlySimpleSecret(secret GenericSecret) bool {
return secret.Current != "" || secret.Previous != "" || secret.Next != "" || secret.Username != "" || secret.Password != ""
}
func notOnlyVersionedSecret(secret GenericSecret) bool {
return secret.Value != "" || secret.Username != "" || secret.Password != ""
}
func notOnlyCredentialSecret(secret GenericSecret) bool {
return secret.Value != "" || secret.Current != "" || secret.Previous != "" || secret.Next != ""
}
// GenericSecret is a placeholder to fit all types of secrets when parsing the
// Secret JSON before processing them into their more typed equivalents.
type GenericSecret struct {
Type string `json:"type"`
Value string `json:"value"`
Encoding Encoding `json:"encoding"`
Current string `json:"current"`
Previous string `json:"previous"`
Next string `json:"next"`
Username string `json:"username"`
Password string `json:"password"`
}
// Vault provides authentication credentials so that applications can directly
// connect to Vault for more complicated use cases.
type Vault struct {
URL string `json:"url"`
Token string `json:"token"`
}
// NewSecrets parses and validates the secret JSON provided by the reader.
func NewSecrets(r io.Reader) (*Secrets, error) {
var secretsDocument Document
err := json.NewDecoder(r).Decode(&secretsDocument)
if err != nil {
return nil, err
}
return secretsValidate(secretsDocument)
}
// FromDir parses a directory and returns its secrets
func FromDir(dir fs.FS) (*Secrets, error) {
secretsDocument, err := walkCSIDirectory(dir)
if err != nil {
return nil, err
}
return secretsValidate(secretsDocument)
}
func secretsValidate(secretsDocument Document) (*Secrets, error) {
secrets := &Secrets{
simpleSecrets: make(map[string]SimpleSecret),
versionedSecrets: make(map[string]VersionedSecret),
credentialSecrets: make(map[string]CredentialSecret),
vault: secretsDocument.Vault,
}
if err := secretsDocument.Validate(); err != nil {
return nil, err
}
for key, secret := range secretsDocument.Secrets {
switch secret.Type {
case "simple":
simple, err := newSimpleSecret(&secret)
if err != nil {
return nil, err
}
secrets.simpleSecrets[key] = simple
case "versioned":
versioned, err := newVersionedSecret(&secret)
if err != nil {
return nil, err
}
secrets.versionedSecrets[key] = versioned
case "credential":
credential, err := newCredentialSecret(&secret)
if err != nil {
return nil, err
}
secrets.credentialSecrets[key] = credential
default:
return nil, fmt.Errorf(
"secrets.NewSecrets: encountered unknown secret type %q for secret %q",
secret.Type,
key,
)
}
}
return secrets, nil
}
type notCSIError struct {
err error
}
func (e notCSIError) Error() string {
return fmt.Sprintf("configured directory does not appear to be the root of a Vault CSI mount point: %v", e.err)
}
func (e notCSIError) Unwrap() error {
return e.err
}
// walkCSIDirectory parses a directory for vault secrets and merges them into one object
func walkCSIDirectory(dir fs.FS) (Document, error) {
const (
// This is where k8s actually writes the content,
// ref: https://pkg.go.dev/sigs.k8s.io/secrets-store-csi-driver/pkg/util/fileutil#AtomicWriter.Write
k8sSubdirectory = "..data"
)
secretsDocument := Document{
Secrets: make(map[string]GenericSecret),
}
err := fs.WalkDir(
dir,
k8sSubdirectory,
func(path string, d fs.DirEntry, err error) error {
if err != nil {
if path == k8sSubdirectory && errors.Is(err, fs.ErrNotExist) {
return notCSIError{err: err}
}
return err
}
if d.IsDir() {
return nil
}
relPath, err := filepath.Rel(k8sSubdirectory, path)
if err != nil {
// Should not happen as this means path is not under k8sSubdirectory,
// but just in case
return nil
}
file, err := dir.Open(path)
if err != nil {
return err
}
defer file.Close()
var secretFile CSIFile
err = json.NewDecoder(file).Decode(&secretFile)
if err != nil {
return fmt.Errorf("decoding %q: %w", path, err)
}
secretsDocument.Secrets[relPath] = secretFile.Secret
return nil
},
)
if err != nil {
return Document{}, fmt.Errorf("secrets.walkCSIDirectory: %w", err)
}
return secretsDocument, nil
}