casbin

casbin

Another casbin implementation in golang.

Installation

go get github.com/sdcxtech/casbin

Quick start

package main

import (
	"fmt"
	"strings"

	"github.com/sdcxtech/casbin"
	"github.com/sdcxtech/casbin/core"
	"github.com/sdcxtech/casbin/effector"
	"github.com/sdcxtech/casbin/load"
)

func main() {
	policy, _ := core.NewAssertionSchema("sub, obj, act")
	request, _ := core.NewAssertionSchema("sub, obj, act")

	roles := core.RolesSchema{
		"g": {Type: core.RoleTypeWithoutDomain},
	}

	matchers, _ := core.MatchersConfig{
		Roles: roles,
		Define: map[string]string{
			"m": "g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act",
		},
	}.New()

	model := core.NewModel(policy, request, roles, effector.NewAllowOverride(), matchers)

	policies := strings.NewReader(`
p, staff, order, get
g, admin, staff
`)

	enforcer, _ := casbin.NewEnforcer(model, load.NewCSVIterator(policies))
	allow, _ := enforcer.Enforce(casbin.Request("admin", "order", "get"))

	fmt.Println(allow) // true
}

Model config

Models can also be loaded from a viper.Viper instance, so the concrete file format can be TOML, YAML, JSON, or anything else Viper supports.

[request_definition]
r = "sub, dom, obj, act"

[policy_definition]
p = "sub, obj, act, eft"

[role_definition]
g = "_, _, _"
g1 = "_, _"

[policy_effect]
type = "allow-and-deny"
key = "eft"

[matchers]
m = "g(r.sub, p.sub, r.dom) && r.obj == p.obj && r.act == p.act"

model, err := load.ModelFromViper(v)

Supported effect types:

• allow-override: allow when any policy matches. No effect field is required.
• deny-override: allow unless a matched policy has effect deny.
• allow-and-deny: allow when a policy with effect allow matches and no matched policy has effect deny.

deny-override and allow-and-deny require policy_effect.key to name a policy field whose value is allow or deny.

Policies

Use load.NewCSVIterator to load policy and role rows from an io.Reader. The first CSV column is the section key, such as p for policies or g for a role relation. Lines starting with # are comments.

p, staff, order, get
g, admin, staff

For a role definition with domain (g = "_, _, _"), role rows use from, to, domain:

g, alice, admin, tenant1

Matchers

Matchers are CEL expressions. Request values are available as r.<field>, policy values are available as p.<field>, and role functions use the names from [role_definition].

You can register string match helpers as CEL extension functions:

model, err := load.ModelFromViper(
	v,
	load.ExtensionFuncs(
		keymatch.ToExtensionFunc("globMatch", keymatch.GlobMatch),
		keymatch.ToExtensionFunc("regexMatch", keymatch.NewRegexMatch()),
		keymatch.ToExtensionFunc("ipMatch", keymatch.IPMatch),
	),
)

Then use them from a matcher:

[matchers]
m = "g(r.sub, p.sub) && globMatch(r.obj, p.obj) && r.act == p.act"

Per-request options

Enforce accepts options for one call without changing the enforcer:

• casbin.UseMatcher(name) selects a matcher other than the default m.
• casbin.WithRawPolicies(rows) injects extra raw policies for this call.
• casbin.WithPolicies(policies) injects parsed policies for this call.
• casbin.OnlyInjectedPolicies() ignores the enforcer's loaded policies.
• casbin.WithRoleGraphs(key, graphs...) injects role graphs for this call.

Difference with the official casbin implementation

• Use google Common Expression Language as the matcher expression language.
• Assertion field in policy and request only can be string type. So there is no support for ABAC model.
• Only implement the core feature checking permissions. Not include policies and roles management which should be implemented in a different Bounded Context.

License

Released under the MIT License.