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caddy/modules/caddyhttp/caddyauth/command.go
Matthew Holt 937ec34201
caddyauth: Prevent user enumeration by timing
Always follow the code path of hashing and comparing a plaintext
password even if the account is not found by the given username; this
ensures that similar CPU cycles are spent for both valid and invalid
usernames.

Thanks to @tylerlm for helping and looking into this!
2020-10-31 10:51:05 -06:00

134 lines
3.6 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 (
"bufio"
"bytes"
"encoding/base64"
"flag"
"fmt"
"os"
"os/signal"
"github.com/caddyserver/caddy/v2"
caddycmd "github.com/caddyserver/caddy/v2/cmd"
"golang.org/x/crypto/ssh/terminal"
)
func init() {
caddycmd.RegisterCommand(caddycmd.Command{
Name: "hash-password",
Func: cmdHashPassword,
Usage: "[--algorithm <name>] [--salt <string>] [--plaintext <password>]",
Short: "Hashes a password and writes base64",
Long: `
Convenient way to hash a plaintext password. The resulting
hash is written to stdout as a base64 string.
--plaintext, when omitted, will be read from stdin. If
Caddy is attached to a controlling tty, the plaintext will
not be echoed.
--algorithm may be bcrypt or scrypt. If script, the default
parameters are used.
Use the --salt flag for algorithms which require a salt to
be provided (scrypt).
`,
Flags: func() *flag.FlagSet {
fs := flag.NewFlagSet("hash-password", flag.ExitOnError)
fs.String("algorithm", "bcrypt", "Name of the hash algorithm")
fs.String("plaintext", "", "The plaintext password")
fs.String("salt", "", "The password salt")
return fs
}(),
})
}
func cmdHashPassword(fs caddycmd.Flags) (int, error) {
var err error
algorithm := fs.String("algorithm")
plaintext := []byte(fs.String("plaintext"))
salt := []byte(fs.String("salt"))
if len(plaintext) == 0 {
fd := int(os.Stdin.Fd())
if terminal.IsTerminal(fd) {
// ensure the terminal state is restored on SIGINT
state, _ := terminal.GetState(fd)
c := make(chan os.Signal)
signal.Notify(c, os.Interrupt)
go func() {
<-c
_ = terminal.Restore(fd, state)
os.Exit(caddy.ExitCodeFailedStartup)
}()
defer signal.Stop(c)
fmt.Fprint(os.Stderr, "Enter password: ")
plaintext, err = terminal.ReadPassword(fd)
fmt.Fprintln(os.Stderr)
if err != nil {
return caddy.ExitCodeFailedStartup, err
}
fmt.Fprint(os.Stderr, "Confirm password: ")
confirmation, err := terminal.ReadPassword(fd)
fmt.Fprintln(os.Stderr)
if err != nil {
return caddy.ExitCodeFailedStartup, err
}
if !bytes.Equal(plaintext, confirmation) {
return caddy.ExitCodeFailedStartup, fmt.Errorf("password does not match")
}
} else {
rd := bufio.NewReader(os.Stdin)
plaintext, err = rd.ReadBytes('\n')
if err != nil {
return caddy.ExitCodeFailedStartup, err
}
plaintext = plaintext[:len(plaintext)-1] // Trailing newline
}
if len(plaintext) == 0 {
return caddy.ExitCodeFailedStartup, fmt.Errorf("plaintext is required")
}
}
var hash []byte
switch algorithm {
case "bcrypt":
hash, err = BcryptHash{}.Hash(plaintext, nil)
case "scrypt":
def := ScryptHash{}
def.SetDefaults()
hash, err = def.Hash(plaintext, salt)
default:
return caddy.ExitCodeFailedStartup, fmt.Errorf("unrecognized hash algorithm: %s", algorithm)
}
if err != nil {
return caddy.ExitCodeFailedStartup, err
}
hashBase64 := base64.StdEncoding.EncodeToString(hash)
fmt.Println(hashBase64)
return 0, nil
}