distribution/registry/auth/htpasswd/access.go

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// Package htpasswd provides a simple authentication scheme that checks for the
// user credential hash in an htpasswd formatted file in a configuration-determined
// location.
//
// This authentication method MUST be used under TLS, as simple token-replay attack is possible.
package htpasswd
import (
"context"
"crypto/rand"
"encoding/base64"
"fmt"
"net/http"
"os"
"path/filepath"
"sync"
"time"
"golang.org/x/crypto/bcrypt"
"github.com/distribution/distribution/v3/internal/dcontext"
"github.com/distribution/distribution/v3/registry/auth"
"github.com/sirupsen/logrus"
)
func init() {
if err := auth.Register("htpasswd", auth.InitFunc(newAccessController)); err != nil {
logrus.Errorf("failed to register htpasswd auth: %v", err)
}
}
type accessController struct {
realm string
path string
modtime time.Time
mu sync.Mutex
htpasswd *htpasswd
}
var _ auth.AccessController = &accessController{}
func newAccessController(options map[string]interface{}) (auth.AccessController, error) {
realm, present := options["realm"]
if _, ok := realm.(string); !present || !ok {
return nil, fmt.Errorf(`"realm" must be set for htpasswd access controller`)
}
pathOpt, present := options["path"]
path, ok := pathOpt.(string)
if !present || !ok {
return nil, fmt.Errorf(`"path" must be set for htpasswd access controller`)
}
if err := createHtpasswdFile(path); err != nil {
return nil, err
}
return &accessController{realm: realm.(string), path: path}, nil
}
func (ac *accessController) Authorized(req *http.Request, accessRecords ...auth.Access) (*auth.Grant, error) {
username, password, ok := req.BasicAuth()
if !ok {
return nil, &challenge{
realm: ac.realm,
err: auth.ErrInvalidCredential,
}
}
// Dynamically parsing the latest account list
fstat, err := os.Stat(ac.path)
if err != nil {
return nil, err
}
lastModified := fstat.ModTime()
ac.mu.Lock()
if ac.htpasswd == nil || !ac.modtime.Equal(lastModified) {
ac.modtime = lastModified
f, err := os.Open(ac.path)
if err != nil {
ac.mu.Unlock()
return nil, err
}
defer f.Close()
h, err := newHTPasswd(f)
if err != nil {
ac.mu.Unlock()
return nil, err
}
ac.htpasswd = h
}
localHTPasswd := ac.htpasswd
ac.mu.Unlock()
if err := localHTPasswd.authenticateUser(username, password); err != nil {
dcontext.GetLogger(req.Context()).Errorf("error authenticating user %q: %v", username, err)
return nil, &challenge{
realm: ac.realm,
err: auth.ErrAuthenticationFailure,
}
}
return &auth.Grant{User: auth.UserInfo{Name: username}}, nil
}
// challenge implements the auth.Challenge interface.
type challenge struct {
realm string
err error
}
var _ auth.Challenge = challenge{}
// SetHeaders sets the basic challenge header on the response.
func (ch challenge) SetHeaders(r *http.Request, w http.ResponseWriter) {
w.Header().Set("WWW-Authenticate", fmt.Sprintf("Basic realm=%q", ch.realm))
}
func (ch challenge) Error() string {
return fmt.Sprintf("basic authentication challenge for realm %q: %s", ch.realm, ch.err)
}
// createHtpasswdFile creates and populates htpasswd file with a new user in case the file is missing
func createHtpasswdFile(path string) error {
if f, err := os.Open(path); err == nil {
f.Close()
return nil
} else if !os.IsNotExist(err) {
return err
}
if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
return err
}
f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, 0o600)
if err != nil {
return fmt.Errorf("failed to open htpasswd path %s", err)
}
defer f.Close()
var secretBytes [32]byte
if _, err := rand.Read(secretBytes[:]); err != nil {
return err
}
pass := base64.RawURLEncoding.EncodeToString(secretBytes[:])
encryptedPass, err := bcrypt.GenerateFromPassword([]byte(pass), bcrypt.DefaultCost)
if err != nil {
return err
}
if _, err := f.Write([]byte(fmt.Sprintf("docker:%s", string(encryptedPass[:])))); err != nil {
return err
}
dcontext.GetLoggerWithFields(context.Background(), map[interface{}]interface{}{
"user": "docker",
"password": pass,
}).Warnf("htpasswd is missing, provisioning with default user")
return nil
}