distribution/docs/auth/basic/access.go
Stephen J Day 14f3b07db0 Harden basic auth implementation
After consideration, the basic authentication implementation has been
simplified to only support bcrypt entries in an htpasswd file. This greatly
increases the security of the implementation by reducing the possibility of
timing attacks and other problems trying to detect the password hash type.

Also, the htpasswd file is only parsed at startup, ensuring that the file can
be edited and not effect ongoing requests. Newly added passwords take effect on
restart. Subsequently, password hash entries are now stored in a map.

Test cases have been modified accordingly.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-06-10 19:38:56 -07:00

102 lines
2.6 KiB
Go

// Package basic 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 basic
import (
"errors"
"fmt"
"net/http"
"os"
ctxu "github.com/docker/distribution/context"
"github.com/docker/distribution/registry/auth"
"golang.org/x/net/context"
)
var (
// ErrInvalidCredential is returned when the auth token does not authenticate correctly.
ErrInvalidCredential = errors.New("invalid authorization credential")
// ErrAuthenticationFailure returned when authentication failure to be presented to agent.
ErrAuthenticationFailure = errors.New("authentication failured")
)
type accessController struct {
realm string
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 basic access controller`)
}
path, present := options["path"]
if _, ok := path.(string); !present || !ok {
return nil, fmt.Errorf(`"path" must be set for basic access controller`)
}
f, err := os.Open(path.(string))
if err != nil {
return nil, err
}
defer f.Close()
h, err := newHTPasswd(f)
if err != nil {
return nil, err
}
return &accessController{realm: realm.(string), htpasswd: h}, nil
}
func (ac *accessController) Authorized(ctx context.Context, accessRecords ...auth.Access) (context.Context, error) {
req, err := ctxu.GetRequest(ctx)
if err != nil {
return nil, err
}
username, password, ok := req.BasicAuth()
if !ok {
return nil, &challenge{
realm: ac.realm,
err: ErrInvalidCredential,
}
}
if err := ac.htpasswd.authenticateUser(username, password); err != nil {
ctxu.GetLogger(ctx).Errorf("error authenticating user %q: %v", username, err)
return nil, &challenge{
realm: ac.realm,
err: ErrAuthenticationFailure,
}
}
return auth.WithUser(ctx, auth.UserInfo{Name: username}), nil
}
// challenge implements the auth.Challenge interface.
type challenge struct {
realm string
err error
}
func (ch *challenge) ServeHTTP(w http.ResponseWriter, r *http.Request) {
header := fmt.Sprintf("Basic realm=%q", ch.realm)
w.Header().Set("WWW-Authenticate", header)
w.WriteHeader(http.StatusUnauthorized)
}
func (ch *challenge) Error() string {
return fmt.Sprintf("basic authentication challenge: %#v", ch)
}
func init() {
auth.Register("basic", auth.InitFunc(newAccessController))
}