DockerCLI/vendor/github.com/theupdateframework/notary/trustmanager/keys.go

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package trustmanager
import (
"encoding/pem"
"errors"
"fmt"
"io"
"io/ioutil"
"path/filepath"
"sort"
"strings"
"github.com/sirupsen/logrus"
"github.com/theupdateframework/notary"
tufdata "github.com/theupdateframework/notary/tuf/data"
"github.com/theupdateframework/notary/tuf/utils"
)
// Exporter is a simple interface for the two functions we need from the Storage interface
type Exporter interface {
Get(string) ([]byte, error)
ListFiles() []string
}
// Importer is a simple interface for the one function we need from the Storage interface
type Importer interface {
Set(string, []byte) error
}
// ExportKeysByGUN exports all keys filtered to a GUN
func ExportKeysByGUN(to io.Writer, s Exporter, gun string) error {
keys := s.ListFiles()
sort.Strings(keys) // ensure consistency. ListFiles has no order guarantee
for _, loc := range keys {
keyFile, err := s.Get(loc)
if err != nil {
logrus.Warn("Could not parse key file at ", loc)
continue
}
block, _ := pem.Decode(keyFile)
keyGun := block.Headers["gun"]
if keyGun == gun { // must be full GUN match
if err := ExportKeys(to, s, loc); err != nil {
return err
}
}
}
return nil
}
// ExportKeysByID exports all keys matching the given ID
func ExportKeysByID(to io.Writer, s Exporter, ids []string) error {
want := make(map[string]struct{})
for _, id := range ids {
want[id] = struct{}{}
}
keys := s.ListFiles()
for _, k := range keys {
id := filepath.Base(k)
if _, ok := want[id]; ok {
if err := ExportKeys(to, s, k); err != nil {
return err
}
}
}
return nil
}
// ExportKeys copies a key from the store to the io.Writer
func ExportKeys(to io.Writer, s Exporter, from string) error {
// get PEM block
k, err := s.Get(from)
if err != nil {
return err
}
// parse PEM blocks if there are more than one
for block, rest := pem.Decode(k); block != nil; block, rest = pem.Decode(rest) {
// add from path in a header for later import
block.Headers["path"] = from
// write serialized PEM
err = pem.Encode(to, block)
if err != nil {
return err
}
}
return nil
}
// ImportKeys expects an io.Reader containing one or more PEM blocks.
// It reads PEM blocks one at a time until pem.Decode returns a nil
// block.
// Each block is written to the subpath indicated in the "path" PEM
// header. If the file already exists, the file is truncated. Multiple
// adjacent PEMs with the same "path" header are appended together.
func ImportKeys(from io.Reader, to []Importer, fallbackRole string, fallbackGUN string, passRet notary.PassRetriever) error {
// importLogic.md contains a small flowchart I made to clear up my understand while writing the cases in this function
// it is very rough, but it may help while reading this piece of code
data, err := ioutil.ReadAll(from)
if err != nil {
return err
}
var (
writeTo string
toWrite []byte
errBlocks []string
)
for block, rest := pem.Decode(data); block != nil; block, rest = pem.Decode(rest) {
handleLegacyPath(block)
setFallbacks(block, fallbackGUN, fallbackRole)
loc, err := checkValidity(block)
if err != nil {
// already logged in checkValidity
errBlocks = append(errBlocks, err.Error())
continue
}
// the path header is not of any use once we've imported the key so strip it away
delete(block.Headers, "path")
// we are now all set for import but let's first encrypt the key
blockBytes := pem.EncodeToMemory(block)
// check if key is encrypted, note: if it is encrypted at this point, it will have had a path header
if privKey, err := utils.ParsePEMPrivateKey(blockBytes, ""); err == nil {
// Key is not encrypted- ask for a passphrase and encrypt this key
var chosenPassphrase string
for attempts := 0; ; attempts++ {
var giveup bool
chosenPassphrase, giveup, err = passRet(loc, block.Headers["role"], true, attempts)
if err == nil {
break
}
if giveup || attempts > 10 {
return errors.New("maximum number of passphrase attempts exceeded")
}
}
blockBytes, err = utils.ConvertPrivateKeyToPKCS8(privKey, tufdata.RoleName(block.Headers["role"]), tufdata.GUN(block.Headers["gun"]), chosenPassphrase)
if err != nil {
return errors.New("failed to encrypt key with given passphrase")
}
}
if loc != writeTo {
// next location is different from previous one. We've finished aggregating
// data for the previous file. If we have data, write the previous file,
// clear toWrite and set writeTo to the next path we're going to write
if toWrite != nil {
if err = importToStores(to, writeTo, toWrite); err != nil {
return err
}
}
// set up for aggregating next file's data
toWrite = nil
writeTo = loc
}
toWrite = append(toWrite, blockBytes...)
}
if toWrite != nil { // close out final iteration if there's data left
return importToStores(to, writeTo, toWrite)
}
if len(errBlocks) > 0 {
return fmt.Errorf("failed to import all keys: %s", strings.Join(errBlocks, ", "))
}
return nil
}
func handleLegacyPath(block *pem.Block) {
// if there is a legacy path then we set the gun header from this path
// this is the case when a user attempts to import a key bundle generated by an older client
if rawPath := block.Headers["path"]; rawPath != "" && rawPath != filepath.Base(rawPath) {
// this is a legacy filepath and we should try to deduce the gun name from it
pathWOFileName := filepath.Dir(rawPath)
if strings.HasPrefix(pathWOFileName, notary.NonRootKeysSubdir) {
// remove the notary keystore-specific segment of the path, and any potential leading or trailing slashes
gunName := strings.Trim(strings.TrimPrefix(pathWOFileName, notary.NonRootKeysSubdir), "/")
if gunName != "" {
block.Headers["gun"] = gunName
}
}
block.Headers["path"] = filepath.Base(rawPath)
}
}
func setFallbacks(block *pem.Block, fallbackGUN, fallbackRole string) {
if block.Headers["gun"] == "" {
if fallbackGUN != "" {
block.Headers["gun"] = fallbackGUN
}
}
if block.Headers["role"] == "" {
if fallbackRole == "" {
block.Headers["role"] = notary.DefaultImportRole
} else {
block.Headers["role"] = fallbackRole
}
}
}
// checkValidity ensures the fields in the pem headers are valid and parses out the location.
// While importing a collection of keys, errors from this function should result in only the
// current pem block being skipped.
func checkValidity(block *pem.Block) (string, error) {
// A root key or a delegations key should not have a gun
// Note that a key that is not any of the canonical roles (except root) is a delegations key and should not have a gun
switch block.Headers["role"] {
case tufdata.CanonicalSnapshotRole.String(), tufdata.CanonicalTargetsRole.String(), tufdata.CanonicalTimestampRole.String():
// check if the key is missing a gun header or has an empty gun and error out since we don't know what gun it belongs to
if block.Headers["gun"] == "" {
logrus.Warnf("failed to import key (%s) to store: Cannot have canonical role key without a gun, don't know what gun it belongs to", block.Headers["path"])
return "", errors.New("invalid key pem block")
}
default:
delete(block.Headers, "gun")
}
loc, ok := block.Headers["path"]
// only if the path isn't specified do we get into this parsing path logic
if !ok || loc == "" {
// if the path isn't specified, we will try to infer the path rel to trust dir from the role (and then gun)
// parse key for the keyID which we will save it by.
// if the key is encrypted at this point, we will generate an error and continue since we don't know the ID to save it by
decodedKey, err := utils.ParsePEMPrivateKey(pem.EncodeToMemory(block), "")
if err != nil {
logrus.Warn("failed to import key to store: Invalid key generated, key may be encrypted and does not contain path header")
return "", errors.New("invalid key pem block")
}
loc = decodedKey.ID()
}
return loc, nil
}
func importToStores(to []Importer, path string, bytes []byte) error {
var err error
for _, i := range to {
if err = i.Set(path, bytes); err != nil {
logrus.Errorf("failed to import key to store: %s", err.Error())
continue
}
break
}
return err
}