mirror of
https://github.com/caddyserver/caddy.git
synced 2025-10-26 08:12:43 -04:00
303 lines
9.5 KiB
Go
303 lines
9.5 KiB
Go
// 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 (
|
|
"encoding/base64"
|
|
"encoding/hex"
|
|
"encoding/json"
|
|
"fmt"
|
|
weakrand "math/rand"
|
|
"net/http"
|
|
"strings"
|
|
"sync"
|
|
|
|
"golang.org/x/sync/singleflight"
|
|
|
|
"github.com/caddyserver/caddy/v2"
|
|
)
|
|
|
|
func init() {
|
|
caddy.RegisterModule(HTTPBasicAuth{})
|
|
}
|
|
|
|
// HTTPBasicAuth facilitates HTTP basic authentication.
|
|
type HTTPBasicAuth struct {
|
|
// The algorithm with which the passwords are hashed. Default: bcrypt
|
|
HashRaw json.RawMessage `json:"hash,omitempty" caddy:"namespace=http.authentication.hashes inline_key=algorithm"`
|
|
|
|
// The list of accounts to authenticate.
|
|
AccountList []Account `json:"accounts,omitempty"`
|
|
|
|
// The name of the realm. Default: restricted
|
|
Realm string `json:"realm,omitempty"`
|
|
|
|
// If non-nil, a mapping of plaintext passwords to their
|
|
// hashes will be cached in memory (with random eviction).
|
|
// This can greatly improve the performance of traffic-heavy
|
|
// servers that use secure password hashing algorithms, with
|
|
// the downside that plaintext passwords will be stored in
|
|
// memory for a longer time (this should not be a problem
|
|
// as long as your machine is not compromised, at which point
|
|
// all bets are off, since basicauth necessitates plaintext
|
|
// passwords being received over the wire anyway). Note that
|
|
// a cache hit does not mean it is a valid password.
|
|
HashCache *Cache `json:"hash_cache,omitempty"`
|
|
|
|
Accounts map[string]Account `json:"-"`
|
|
Hash Comparer `json:"-"`
|
|
|
|
// fakePassword is used when a given user is not found,
|
|
// so that timing side-channels can be mitigated: it gives
|
|
// us something to hash and compare even if the user does
|
|
// not exist, which should have similar timing as a user
|
|
// account that does exist.
|
|
fakePassword []byte
|
|
}
|
|
|
|
// CaddyModule returns the Caddy module information.
|
|
func (HTTPBasicAuth) CaddyModule() caddy.ModuleInfo {
|
|
return caddy.ModuleInfo{
|
|
ID: "http.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 {
|
|
hba.HashRaw = json.RawMessage(`{"algorithm": "bcrypt"}`)
|
|
}
|
|
|
|
// load password hasher
|
|
hasherIface, err := ctx.LoadModule(hba, "HashRaw")
|
|
if err != nil {
|
|
return fmt.Errorf("loading password hasher module: %v", err)
|
|
}
|
|
hba.Hash = hasherIface.(Comparer)
|
|
|
|
if hba.Hash == nil {
|
|
return fmt.Errorf("hash is required")
|
|
}
|
|
|
|
// if supported, generate a fake password we can compare against if needed
|
|
if hasher, ok := hba.Hash.(Hasher); ok {
|
|
hba.fakePassword = hasher.FakeHash()
|
|
}
|
|
|
|
repl := caddy.NewReplacer()
|
|
|
|
// load account list
|
|
hba.Accounts = make(map[string]Account)
|
|
for i, acct := range hba.AccountList {
|
|
if _, ok := hba.Accounts[acct.Username]; ok {
|
|
return fmt.Errorf("account %d: username is not unique: %s", i, acct.Username)
|
|
}
|
|
|
|
acct.Username = repl.ReplaceAll(acct.Username, "")
|
|
acct.Password = repl.ReplaceAll(acct.Password, "")
|
|
|
|
if acct.Username == "" || acct.Password == "" {
|
|
return fmt.Errorf("account %d: username and password are required", i)
|
|
}
|
|
|
|
// TODO: Remove support for redundantly-encoded b64-encoded hashes
|
|
// Passwords starting with '$' are likely in Modular Crypt Format,
|
|
// so we don't need to base64 decode them. But historically, we
|
|
// required redundant base64, so we try to decode it otherwise.
|
|
if strings.HasPrefix(acct.Password, "$") {
|
|
acct.password = []byte(acct.Password)
|
|
} else {
|
|
acct.password, err = base64.StdEncoding.DecodeString(acct.Password)
|
|
if err != nil {
|
|
return fmt.Errorf("base64-decoding password: %v", err)
|
|
}
|
|
}
|
|
|
|
hba.Accounts[acct.Username] = acct
|
|
}
|
|
hba.AccountList = nil // allow GC to deallocate
|
|
|
|
if hba.HashCache != nil {
|
|
hba.HashCache.cache = make(map[string]bool)
|
|
hba.HashCache.mu = new(sync.RWMutex)
|
|
hba.HashCache.g = new(singleflight.Group)
|
|
}
|
|
|
|
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 !ok {
|
|
return hba.promptForCredentials(w, nil)
|
|
}
|
|
|
|
account, accountExists := hba.Accounts[username]
|
|
if !accountExists {
|
|
// don't return early if account does not exist; we want
|
|
// to try to avoid side-channels that leak existence, so
|
|
// we use a fake password to simulate realistic CPU cycles
|
|
account.password = hba.fakePassword
|
|
}
|
|
|
|
same, err := hba.correctPassword(account, []byte(plaintextPasswordStr))
|
|
if err != nil || !same || !accountExists {
|
|
return hba.promptForCredentials(w, err)
|
|
}
|
|
|
|
return User{ID: username}, true, nil
|
|
}
|
|
|
|
func (hba HTTPBasicAuth) correctPassword(account Account, plaintextPassword []byte) (bool, error) {
|
|
compare := func() (bool, error) {
|
|
return hba.Hash.Compare(account.password, plaintextPassword)
|
|
}
|
|
|
|
// if no caching is enabled, simply return the result of hashing + comparing
|
|
if hba.HashCache == nil {
|
|
return compare()
|
|
}
|
|
|
|
// compute a cache key that is unique for these input parameters
|
|
cacheKey := hex.EncodeToString(append(account.password, plaintextPassword...))
|
|
|
|
// fast track: if the result of the input is already cached, use it
|
|
hba.HashCache.mu.RLock()
|
|
same, ok := hba.HashCache.cache[cacheKey]
|
|
hba.HashCache.mu.RUnlock()
|
|
if ok {
|
|
return same, nil
|
|
}
|
|
// slow track: do the expensive op, then add it to the cache
|
|
// but perform it in a singleflight group so that multiple
|
|
// parallel requests using the same password don't cause a
|
|
// thundering herd problem by all performing the same hashing
|
|
// operation before the first one finishes and caches it.
|
|
v, err, _ := hba.HashCache.g.Do(cacheKey, func() (any, error) {
|
|
return compare()
|
|
})
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
same = v.(bool)
|
|
hba.HashCache.mu.Lock()
|
|
if len(hba.HashCache.cache) >= 1000 {
|
|
hba.HashCache.makeRoom() // keep cache size under control
|
|
}
|
|
hba.HashCache.cache[cacheKey] = same
|
|
hba.HashCache.mu.Unlock()
|
|
|
|
return same, nil
|
|
}
|
|
|
|
func (hba HTTPBasicAuth) promptForCredentials(w http.ResponseWriter, err error) (User, bool, error) {
|
|
// browsers show a message that says something like:
|
|
// "The website says: <realm>"
|
|
// 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, err
|
|
}
|
|
|
|
// Cache enables caching of basic auth results. This is especially
|
|
// helpful for secure password hashes which can be expensive to
|
|
// compute on every HTTP request.
|
|
type Cache struct {
|
|
mu *sync.RWMutex
|
|
g *singleflight.Group
|
|
|
|
// map of concatenated hashed password + plaintext password, to result
|
|
cache map[string]bool
|
|
}
|
|
|
|
// makeRoom deletes about 1/10 of the items in the cache
|
|
// in order to keep its size under control. It must not be
|
|
// called without a lock on c.mu.
|
|
func (c *Cache) makeRoom() {
|
|
// we delete more than just 1 entry so that we don't have
|
|
// to do this on every request; assuming the capacity of
|
|
// the cache is on a long tail, we can save a lot of CPU
|
|
// time by doing a whole bunch of deletions now and then
|
|
// we won't have to do them again for a while
|
|
numToDelete := len(c.cache) / 10
|
|
if numToDelete < 1 {
|
|
numToDelete = 1
|
|
}
|
|
for deleted := 0; deleted <= numToDelete; deleted++ {
|
|
// Go maps are "nondeterministic" not actually random,
|
|
// so although we could just chop off the "front" of the
|
|
// map with less code, this is a heavily skewed eviction
|
|
// strategy; generating random numbers is cheap and
|
|
// ensures a much better distribution.
|
|
//nolint:gosec
|
|
rnd := weakrand.Intn(len(c.cache))
|
|
i := 0
|
|
for key := range c.cache {
|
|
if i == rnd {
|
|
delete(c.cache, key)
|
|
break
|
|
}
|
|
i++
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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 is hashedPassword, false
|
|
// otherwise. An error is returned only if
|
|
// there is a technical/configuration error.
|
|
Compare(hashedPassword, plaintextPassword []byte) (bool, error)
|
|
}
|
|
|
|
// Hasher is a type that can generate a secure hash
|
|
// given a plaintext. Hashing modules which implement
|
|
// this interface can be used with the hash-password
|
|
// subcommand as well as benefitting from anti-timing
|
|
// features. A hasher also returns a fake hash which
|
|
// can be used for timing side-channel mitigation.
|
|
type Hasher interface {
|
|
Hash(plaintext []byte) ([]byte, error)
|
|
FakeHash() []byte
|
|
}
|
|
|
|
// Account contains a username and password.
|
|
type Account struct {
|
|
// A user's username.
|
|
Username string `json:"username"`
|
|
|
|
// The user's hashed password, in Modular Crypt Format (with `$` prefix)
|
|
// or base64-encoded.
|
|
Password string `json:"password"`
|
|
|
|
password []byte
|
|
}
|
|
|
|
// Interface guards
|
|
var (
|
|
_ caddy.Provisioner = (*HTTPBasicAuth)(nil)
|
|
_ Authenticator = (*HTTPBasicAuth)(nil)
|
|
)
|