RBAC - Simple, concurrent Role Based Access Control(GO)

RBAC is role based access control library for GOlang. At core uses sync.Map so, it can be used from multiple goroutines concurrently. "Keep it simple" is also in core.

It supports role inheritance.

It can be used in middleware(example for echo framework is given )

Go 1.9+ is required.

It is built on;

Type	Description	Example
Action	Defines what can possible for a permission	Create,Read,Update...
Permission	Defines permission related to a resource to be accessed	users
Role	Defines group of permissions with defined actions	admin

Usage

Library usage has 2 phases:

• Development
• Runtime

Development Phase

First get an instance for RBAC

import "github.com/euroteltr/rbac"

R := rbac.New(nil)
// you can pass a logger to constructor also:
// R := rbac.New(rbac.ConsoleLogger)

During development you will register your permissions for your each resource with valid actions for that permission:

// You can also use rbac.CRUD for those crud actions
usersPerm, err := R.RegisterPermission("users", "User resource", rbac.Create, rbac.Read, rbac.Update, rbac.Delete)
if err != nil {
    panic(err)
}

userPerm is defined with CRUD actions, which means that any action not in that list will be invalid. You can define your own actions( like ApproveAction := rbac.Action("approve")) and add them also.

Runtime Phase

At run time we define our roles and permit permissions to them.

adminRole, err := R.RegisterRole("admin", "Admin role")
if err != nil {
    fmt.Printf("can not add admin role, err: %v\n", err)
}
if err = R.Permit(adminRole.ID, usersPerm, rbac.CRUD, ApproveAction); err != nil {
    fmt.Errorf("can not permit crud and ApproveAction actions to role %s\n", adminRole.ID)
}

Now we can check if a role is granted some permission:

if !R.IsGranted(adminRole.ID, usersPerm, rbac.Write) {
    fmt.Printf("admin role does not have write grant on users\n")
}else{
    fmt.Printf("admin role does have write grant on users\n")
}

// You can also check by perm.ID also
if !R.IsGrantedStr("admin", "users", rbac.CRUD) {
    fmt.Printf("admin role does not have CRUD grants on users\n")
}else{
    fmt.Printf("admin role does have CRUD grants on users\n")
}

Persisting and Loading

rbac.RBAC is json compatible. You can dump all data in RBAC instance to JSON:

b, err := json.Marshal(R)
if err != nil {
    fmt.Printf("rback marshall failed with %v\n", err)
}else{
    fmt.Printf("RBAC: %s", b)
}

Also you can use builtin SaveJSON function to save to a io.Writer:

filename := "/tmp/rbac.json"
f, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
    fmt.Printf("can not create json file %s, err: %v\n", filename, err)
    return err
}
defer f.Close()
if err = R.SaveJSON(f); err != nil {
    fmt.Printf("unable to save to json file, err:%v\n", err)
}

And load it from file:

filename := "/tmp/rbac.json"
f, err := os.Open(filename)
if err != nil {
    return err
}
defer f.Close()
if err = R.LoadJSON(f); err != nil {
    fmt.Errorf("unable to load from json file, err:%v\n", err)
}

In dumped JSON root permissions part is just for reference. Root roles is the part you can modify in file and reload it to define Roles with Permissions.

{
  "permissions": [
    {
      "id": "users",
      "description": "User resource",
      "actions": [
        "create",
        "read",
        "update",
        "delete"
      ]
    }
  ],
  "roles": [
    {
      "id": "admin",
      "description": "Admin role",
      "grants": {
        "users": [
          "create",
          "read",
          "update",
          "delete"
        ]
      },
      "parents": []
    }
  ]
}

Role inheritance

A Role can have parent Roles. You can add a parent Role like this:

// Add a new role
sysAdmRole, err := R.RegisterRole("sysadm", "System admin role")
if err != nil {
    fmt.Printf("can not add agent role, err: %v\n", err)
}

// Now add adminRole as parent
if err = sysAdmRole.AddParent(adminRole); err != nil {
    fmt.Printf("adding parent role failed with: %v\n", err)
}

// Now all permissions in adminRole will be also valid for sysAdmRole
if R.IsGranted(sysAdmRole.ID, usersPerm, rbac.CRUD) {
    fmt.Printf("sysadmin role has all crud actions granted\n")
}

If circular parent reference is found, you'll get error while running AddParent.

Usage as middleware

You can check example middleware function for echo framework here

Middleware usage with granular permissions

If you want user role may modify his own user resource, but not others, you can build a wrapper for RBAC.IsGranted function like(example for echo framework:

// idParam is the parameter name where user_id for data will be gotten
func isGrantedResource(perm *rbac.Permission, action rbac.Action, idParam string) echo.MiddlewareFunc {
    return func(next echo.HandlerFunc) echo.HandlerFunc {
        return func(c echo.Context) error {
            rolesI := c.Get("roles")
            if rolesI == nil {
                log.Errorf("No rbac roles key %s", "roles")
            } else if config.RBAC.AnyGranted(rolesI.([]string), perm, actions...) {
                // Get id parameter from route,form... example from: "user/:id"
                userID, err := strconv.ParseInt(c.Param(idParam), 10, 64)
                if err != nil {
                    return http.StatusBadRequest
                }
                // Get current user_id and check if data belongs to current user
                userIDI := c.Get("user_id")
                if userIDI==nil || userIDI.(int64) != userID {
                    return http.StatusForbidden
                }
                return next(c)
            }
            return echo.ErrUnauthorized
        }
    }
}