fix: 修复权限边界与安全问题

- JWT 密钥改为环境变量/配置文件/随机生成注入，移除硬编码
- AuthMiddleware 用数据库 role 覆盖 claims，降级/禁用即时生效
- 改 role/status 时主动失效目标用户会话
- /ws 支持 JWT 认证（?token=），兼容密码认证，CheckOrigin 改同源校验
- 默认管理员改用随机密码，stdout 与文件双交付
- 登录与 WS 密码认证加限流（5次/分钟）
- role 字段白名单校验（仅 admin/user）
- socket/目录权限可配置（sock_mode/sock_group/sock_dir_mode），默认兼容现状
- 配置文件权限收紧 0644→0600，目录 0755→0700
- 静态文件改用 http.Dir.Open + NoRoute，移除手动路径拼接
- 隧道加 SetReadLimit(1MB) 与单用户连接数上限(3)
- README 补充安全配置与生产部署说明

internal/middleware/auth.go

@@ -12,10 +12,13 @@ import (
 	"github.com/golang-jwt/jwt/v5"
 )
 
-const (
-	jwtSecret   = "lmvpn-jwt-secret-key-2024"
-	tokenExpire = 24 * time.Hour
-)
+const tokenExpire = 24 * time.Hour
+
+var jwtSecret []byte
+
+func SetJWTSecret(secret string) {
+	jwtSecret = []byte(secret)
+}
 
 type Claims struct {
 	SessionID string `json:"session_id,omitempty"`
@@ -38,12 +41,12 @@ func GenerateToken(sessionID string, userID uint, username, role string) (string
 	}
 
 	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
-	return token.SignedString([]byte(jwtSecret))
+	return token.SignedString(jwtSecret)
 }
 
 func ParseToken(tokenStr string) (*Claims, error) {
 	token, err := jwt.ParseWithClaims(tokenStr, &Claims{}, func(token *jwt.Token) (interface{}, error) {
-		return []byte(jwtSecret), nil
+		return jwtSecret, nil
 	})
 	if err != nil {
 		return nil, err
@@ -131,7 +134,7 @@ func AuthMiddleware() gin.HandlerFunc {
 
 		c.Set("user_id", claims.UserID)
 		c.Set("username", claims.Username)
-		c.Set("role", claims.Role)
+		c.Set("role", user.Role)
 		c.Set("session_id", claims.SessionID)
 		c.Next()
 	}

internal/middleware/ratelimit.go

@@ -0,0 +1,86 @@
+package middleware
+
+import (
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/gin-gonic/gin"
+)
+
+type RateLimiter struct {
+	mu       sync.Mutex
+	attempts map[string][]time.Time
+	limit    int
+	window   time.Duration
+}
+
+func NewRateLimiter(limit int, window time.Duration) *RateLimiter {
+	rl := &RateLimiter{
+		attempts: make(map[string][]time.Time),
+		limit:    limit,
+		window:   window,
+	}
+	go rl.cleanup()
+	return rl
+}
+
+func (rl *RateLimiter) Allow(key string) bool {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	now := time.Now()
+	cutoff := now.Add(-rl.window)
+
+	var recent []time.Time
+	for _, t := range rl.attempts[key] {
+		if t.After(cutoff) {
+			recent = append(recent, t)
+		}
+	}
+
+	if len(recent) >= rl.limit {
+		rl.attempts[key] = recent
+		return false
+	}
+
+	recent = append(recent, now)
+	rl.attempts[key] = recent
+	return true
+}
+
+func (rl *RateLimiter) cleanup() {
+	ticker := time.NewTicker(rl.window)
+	defer ticker.Stop()
+	for range ticker.C {
+		rl.mu.Lock()
+		cutoff := time.Now().Add(-rl.window)
+		for key, times := range rl.attempts {
+			var recent []time.Time
+			for _, t := range times {
+				if t.After(cutoff) {
+					recent = append(recent, t)
+				}
+			}
+			if len(recent) == 0 {
+				delete(rl.attempts, key)
+			} else {
+				rl.attempts[key] = recent
+			}
+		}
+		rl.mu.Unlock()
+	}
+}
+
+func LoginRateLimit() gin.HandlerFunc {
+	limiter := NewRateLimiter(5, time.Minute)
+	return func(c *gin.Context) {
+		key := c.ClientIP()
+		if !limiter.Allow(key) {
+			c.JSON(http.StatusTooManyRequests, gin.H{"error": "请求过于频繁，请稍后再试"})
+			c.Abort()
+			return
+		}
+		c.Next()
+	}
+}