From f8366c2f09c77a55dc53038cae0b101263488867 Mon Sep 17 00:00:00 2001 From: Matthew Holt Date: Thu, 10 Oct 2019 14:37:27 -0600 Subject: http: authentication module; hash-password cmd; http_basic provider This implements HTTP basicauth into Caddy 2. The basic auth module will not work with passwords that are not securely hashed, so a subcommand hash-password was added to make it convenient to produce those hashes. Also included is Caddyfile support. Closes #2747. --- modules/caddyhttp/caddyauth/basicauth.go | 164 +++++++++++++++++++++++++++++++ 1 file changed, 164 insertions(+) create mode 100644 modules/caddyhttp/caddyauth/basicauth.go (limited to 'modules/caddyhttp/caddyauth/basicauth.go') diff --git a/modules/caddyhttp/caddyauth/basicauth.go b/modules/caddyhttp/caddyauth/basicauth.go new file mode 100644 index 0000000..b7c002b --- /dev/null +++ b/modules/caddyhttp/caddyauth/basicauth.go @@ -0,0 +1,164 @@ +// Copyright 2015 Matthew Holt and The Caddy 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 caddyauth + +import ( + "crypto/sha256" + "crypto/subtle" + "encoding/json" + "fmt" + "net/http" + + "github.com/caddyserver/caddy/v2" +) + +func init() { + caddy.RegisterModule(HTTPBasicAuth{}) +} + +// HTTPBasicAuth facilitates HTTP basic authentication. +type HTTPBasicAuth struct { + HashRaw json.RawMessage `json:"hash,omitempty"` + AccountList []Account `json:"accounts,omitempty"` + Realm string `json:"realm,omitempty"` + + Accounts map[string]Account `json:"-"` + Hash Comparer `json:"-"` +} + +// CaddyModule returns the Caddy module information. +func (HTTPBasicAuth) CaddyModule() caddy.ModuleInfo { + return caddy.ModuleInfo{ + Name: "http.handlers.authentication.providers.http_basic", + New: func() caddy.Module { return new(HTTPBasicAuth) }, + } +} + +// Provision provisions the HTTP basic auth provider. +func (hba *HTTPBasicAuth) Provision(ctx caddy.Context) error { + if hba.HashRaw == nil { + return fmt.Errorf("passwords must be hashed, so a hash must be defined") + } + + // load password hasher + hashIface, err := ctx.LoadModuleInline("algorithm", "http.handlers.authentication.hashes", hba.HashRaw) + if err != nil { + return fmt.Errorf("loading password hasher module: %v", err) + } + hba.Hash = hashIface.(Comparer) + hba.HashRaw = nil // allow GC to deallocate + + if hba.Hash == nil { + return fmt.Errorf("hash is required") + } + + // load account list + hba.Accounts = make(map[string]Account) + for _, acct := range hba.AccountList { + if _, ok := hba.Accounts[acct.Username]; ok { + return fmt.Errorf("username is not unique: %s", acct.Username) + } + hba.Accounts[acct.Username] = acct + } + hba.AccountList = nil // allow GC to deallocate + + return nil +} + +// Authenticate validates the user credentials in req and returns the user, if valid. +func (hba HTTPBasicAuth) Authenticate(w http.ResponseWriter, req *http.Request) (User, bool, error) { + username, plaintextPasswordStr, ok := req.BasicAuth() + + // if basic auth is missing or invalid, prompt for credentials + if !ok { + // browsers show a message that says something like: + // "The website says: " + // which is kinda dumb, but whatever. + realm := hba.Realm + if realm == "" { + realm = "restricted" + } + + w.Header().Set("WWW-Authenticate", fmt.Sprintf(`Basic realm="%s"`, realm)) + + return User{}, false, nil + } + + plaintextPassword := []byte(plaintextPasswordStr) + + account, accountExists := hba.Accounts[username] + // don't return early if account does not exist; we want + // to try to avoid side-channels that leak existence + + same, err := hba.Hash.Compare(account.Password, plaintextPassword, account.Salt) + if err != nil { + return User{}, false, err + } + if !same || !accountExists { + return User{}, false, nil + } + + return User{ID: username}, true, nil +} + +// Comparer is a type that can securely compare +// a plaintext password with a hashed password +// in constant-time. Comparers should hash the +// plaintext password and then use constant-time +// comparison. +type Comparer interface { + // Compare returns true if the result of hashing + // plaintextPassword with salt is hashedPassword, + // false otherwise. An error is returned only if + // there is a technical/configuration error. + Compare(hashedPassword, plaintextPassword, salt []byte) (bool, error) +} + +type quickComparer struct{} + +func (quickComparer) Compare(theirHash, plaintext, _ []byte) (bool, error) { + ourHash := quickHash(plaintext) + return hashesMatch(ourHash, theirHash), nil +} + +func hashesMatch(pwdHash1, pwdHash2 []byte) bool { + return subtle.ConstantTimeCompare(pwdHash1, pwdHash2) == 1 +} + +// quickHash returns the SHA-256 of v. It +// is not secure for password storage, but +// it is useful for efficiently normalizing +// the length of plaintext passwords for +// constant-time comparisons. +// +// Errors are discarded. +func quickHash(v []byte) []byte { + h := sha256.New() + h.Write([]byte(v)) + return h.Sum(nil) +} + +// Account contains a username, password, and salt (if applicable). +type Account struct { + Username string `json:"username"` + Password []byte `json:"password"` + Salt []byte `json:"salt,omitempty"` // for algorithms where external salt is needed +} + +// Interface guards +var ( + _ caddy.Provisioner = (*HTTPBasicAuth)(nil) + _ Authenticator = (*HTTPBasicAuth)(nil) +) -- cgit v1.2.3