k3s/pkg/authenticator/passwordfile/passwordfile.go
Brad Davidson 239021e759 Consistently use constant-time comparison of password hashes
As per https://github.com/golang/go/issues/47001 even subtle.ConstantTimeCompare should never be used with variable-length inputs, as it will return 0 if the lengths do not match. Switch to consistently using constant-time comparisons of hashes for password checks to avoid any possible side-channel leaks that could be combined with other vectors to discover password lengths.

Signed-off-by: Brad Davidson <brad.davidson@rancher.com>
2023-05-09 13:54:50 -07:00

100 lines
2.8 KiB
Go

/*
Copyright 2015 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package passwordfile
import (
"context"
"encoding/csv"
"fmt"
"io"
"os"
"strings"
"github.com/k3s-io/k3s/pkg/nodepassword"
"k8s.io/klog/v2"
"k8s.io/apiserver/pkg/authentication/authenticator"
"k8s.io/apiserver/pkg/authentication/user"
)
// PasswordAuthenticator authenticates users by password
type PasswordAuthenticator struct {
users map[string]*userPasswordInfo
}
type userPasswordInfo struct {
info *user.DefaultInfo
hash string
}
// NewCSV returns a PasswordAuthenticator, populated from a CSV file.
// The CSV file must contain records in the format "password,username,useruid"
func NewCSV(path string) (*PasswordAuthenticator, error) {
file, err := os.Open(path)
if err != nil {
return nil, err
}
defer file.Close()
recordNum := 0
users := make(map[string]*userPasswordInfo)
reader := csv.NewReader(file)
reader.FieldsPerRecord = -1
for {
record, err := reader.Read()
if err == io.EOF {
break
}
if err != nil {
return nil, err
}
if len(record) < 3 {
return nil, fmt.Errorf("password file '%s' must have at least 3 columns (password, user name, user uid), found %d", path, len(record))
}
hash, err := nodepassword.Hasher.CreateHash(record[0])
if err != nil {
return nil, fmt.Errorf("failed to hash password for username '%s' in password file '%s': %v", record[1], path, err)
}
obj := &userPasswordInfo{
info: &user.DefaultInfo{Name: record[1], UID: record[2]},
hash: hash,
}
if len(record) >= 4 {
obj.info.Groups = strings.Split(record[3], ",")
}
recordNum++
if _, exist := users[obj.info.Name]; exist {
klog.Warningf("duplicate username '%s' has been found in password file '%s', record number '%d'", obj.info.Name, path, recordNum)
}
users[obj.info.Name] = obj
}
return &PasswordAuthenticator{users}, nil
}
// AuthenticatePassword returns user info if authentication is successful, nil otherwise
func (a *PasswordAuthenticator) AuthenticatePassword(ctx context.Context, username, password string) (*authenticator.Response, bool, error) {
user, ok := a.users[username]
if !ok {
return nil, false, nil
}
if err := nodepassword.Hasher.VerifyHash(user.hash, password); err != nil {
return nil, false, nil
}
return &authenticator.Response{User: user.info}, true, nil
}