fix(security): redesign password reset tokens using crypto/rand with server-side storage

- Replace SHA512-based deterministic token with 32-byte crypto/rand token
- Store tokens server-side with 1-hour expiry and single-use semantics
- Remove genToken (previously broken due to time.Add immutability bug)
- Add CSRF double-submit cookie protection to change/lost/reset forms
- Remove token from form action URL (use hidden fields only, POST body)
- Add MailFrom field and SMTP_FROM env var for configurable sender address
- Add SMTP_PASSWORD_FILE env var for secure SMTP password loading
- Add PUBLIC_URL env var and --public-url flag for configurable reset link domain
- Use generic error messages in handlers to avoid information disclosure

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
nemunaire 2026-03-06 14:44:29 +07:00
commit 57775bbf89
9 changed files with 193 additions and 83 deletions

111
lost.go
View file

@ -1,54 +1,64 @@
package main
import (
"crypto/sha512"
"crypto/rand"
"encoding/base64"
"encoding/binary"
"io"
"log"
"net/http"
"os"
"os/exec"
"sync"
"time"
"gopkg.in/gomail.v2"
)
func (l LDAPConn) genToken(dn string, previous bool) string {
hour := time.Now()
// Generate the previous token?
if previous {
hour.Add(time.Hour * -1)
type resetTokenEntry struct {
dn string
expiresAt time.Time
}
var resetTokenStore = struct {
mu sync.Mutex
tokens map[string]resetTokenEntry
}{tokens: make(map[string]resetTokenEntry)}
func generateResetToken() (string, error) {
b := make([]byte, 32)
if _, err := rand.Read(b); err != nil {
return "", err
}
return base64.URLEncoding.EncodeToString(b), nil
}
b := make([]byte, binary.MaxVarintLen64)
binary.PutVarint(b, hour.Round(time.Hour).Unix())
func storeResetToken(token string, dn string) {
resetTokenStore.mu.Lock()
defer resetTokenStore.mu.Unlock()
// Search the email address and current password
entries, err := l.GetEntry(dn)
if err != nil {
log.Println("Unable to generate token:", err)
return "#err"
}
email := ""
curpasswd := ""
for _, e := range entries {
if e.Name == "mail" {
email += e.Values[0]
} else if e.Name == "userPassword" {
curpasswd += e.Values[0]
// Clean expired tokens
now := time.Now()
for t, e := range resetTokenStore.tokens {
if now.After(e.expiresAt) {
delete(resetTokenStore.tokens, t)
}
}
resetTokenStore.tokens[token] = resetTokenEntry{
dn: dn,
expiresAt: now.Add(time.Hour),
}
}
// Hash that
hash := sha512.New()
hash.Write(b)
hash.Write([]byte(dn))
hash.Write([]byte(email))
hash.Write([]byte(curpasswd))
return base64.StdEncoding.EncodeToString(hash.Sum(nil)[:])
func consumeResetToken(token string) (string, bool) {
resetTokenStore.mu.Lock()
defer resetTokenStore.mu.Unlock()
entry, ok := resetTokenStore.tokens[token]
if !ok || time.Now().After(entry.expiresAt) {
delete(resetTokenStore.tokens, token)
return "", false
}
delete(resetTokenStore.tokens, token)
return entry.dn, true
}
func lostPasswordToken(conn *LDAPConn, login string) (string, string, error) {
@ -64,15 +74,31 @@ func lostPasswordToken(conn *LDAPConn, login string) (string, string, error) {
return "", "", err
}
// Generate the token
token := conn.genToken(dn, false)
// Generate a cryptographically random token
token, err := generateResetToken()
if err != nil {
return "", "", err
}
// Store token server-side with expiration
storeResetToken(token, dn)
return token, dn, nil
}
func lostPassword(w http.ResponseWriter, r *http.Request) {
if r.Method != "POST" {
displayTmpl(w, "lost.html", map[string]interface{}{})
csrfToken, err := setCSRFToken(w)
if err != nil {
http.Error(w, "Internal server error", http.StatusInternalServerError)
return
}
displayTmpl(w, "lost.html", map[string]interface{}{"csrf_token": csrfToken})
return
}
if !validateCSRF(r) {
displayTmplError(w, http.StatusForbidden, "lost.html", map[string]interface{}{"error": "Invalid or missing CSRF token. Please try again."})
return
}
@ -80,7 +106,7 @@ func lostPassword(w http.ResponseWriter, r *http.Request) {
conn, err := myLDAP.Connect()
if err != nil || conn == nil {
log.Println(err)
displayTmplError(w, http.StatusInternalServerError, "lost.html", map[string]interface{}{"error": err.Error()})
displayTmplError(w, http.StatusInternalServerError, "lost.html", map[string]interface{}{"error": "Unable to process your request. Please try again later."})
return
}
@ -88,7 +114,8 @@ func lostPassword(w http.ResponseWriter, r *http.Request) {
token, dn, err := lostPasswordToken(conn, r.PostFormValue("login"))
if err != nil {
log.Println(err)
displayTmplError(w, http.StatusInternalServerError, "lost.html", map[string]interface{}{"error": err.Error()})
// Return generic message to avoid user enumeration
displayMsg(w, "If an account with that login exists, a password recovery email has been sent.", http.StatusOK)
return
}
@ -96,7 +123,7 @@ func lostPassword(w http.ResponseWriter, r *http.Request) {
entries, err := conn.GetEntry(dn)
if err != nil {
log.Println(err)
displayTmplError(w, http.StatusInternalServerError, "lost.html", map[string]interface{}{"error": err.Error()})
displayMsg(w, "If an account with that login exists, a password recovery email has been sent.", http.StatusOK)
return
}
@ -113,16 +140,16 @@ func lostPassword(w http.ResponseWriter, r *http.Request) {
if email == "" {
log.Println("Unable to find a valid adress for user " + dn)
displayTmplError(w, http.StatusBadRequest, "lost.html", map[string]interface{}{"error": "We were unable to find a valid email address associated with your account. Please contact an administrator."})
displayMsg(w, "If an account with that login exists, a password recovery email has been sent.", http.StatusOK)
return
}
// Send the email
m := gomail.NewMessage()
m.SetHeader("From", "noreply@nemunai.re")
m.SetHeader("From", myLDAP.MailFrom)
m.SetHeader("To", email)
m.SetHeader("Subject", "SSO nemunai.re: password recovery")
m.SetBody("text/plain", "Hello "+cn+"!\n\nSomeone, and we hope it's you, requested to reset your account password. \nIn order to continue, go to:\n"+BASEURL+"/reset?l="+r.PostFormValue("login")+"&t="+token+"\n\nBest regards,\n-- \nnemunai.re SSO")
m.SetBody("text/plain", "Hello "+cn+"!\n\nSomeone, and we hope it's you, requested to reset your account password. \nIn order to continue, go to:\n"+myPublicURL+"/reset?l="+r.PostFormValue("login")+"&t="+token+"\n\nThis link expires in 1 hour and can only be used once.\n\nBest regards,\n-- \nnemunai.re SSO")
var s gomail.Sender
if myLDAP.MailHost != "" {
@ -130,7 +157,7 @@ func lostPassword(w http.ResponseWriter, r *http.Request) {
s, err = d.Dial()
if err != nil {
log.Println("Unable to connect to email server: " + err.Error())
displayTmplError(w, http.StatusInternalServerError, "lost.html", map[string]interface{}{"error": "Unable to connect to email server: " + err.Error()})
displayTmplError(w, http.StatusInternalServerError, "lost.html", map[string]interface{}{"error": "Unable to send password recovery email. Please try again later."})
return
}
} else {
@ -165,7 +192,7 @@ func lostPassword(w http.ResponseWriter, r *http.Request) {
if err := gomail.Send(s, m); err != nil {
log.Println("Unable to send email: " + err.Error())
displayTmplError(w, http.StatusInternalServerError, "lost.html", map[string]interface{}{"error": "Unable to send email: " + err.Error()})
displayTmplError(w, http.StatusInternalServerError, "lost.html", map[string]interface{}{"error": "Unable to send password recovery email. Please try again later."})
return
}