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rbac.go
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rbac.go
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package rbac
import (
"context"
"encoding/csv"
"errors"
"fmt"
"strings"
"sync"
"time"
"github.com/argoproj/argo-cd/v2/util/assets"
"github.com/argoproj/argo-cd/v2/util/glob"
jwtutil "github.com/argoproj/argo-cd/v2/util/jwt"
"github.com/Knetic/govaluate"
"github.com/casbin/casbin/v2"
"github.com/casbin/casbin/v2/model"
"github.com/casbin/casbin/v2/util"
jwt "github.com/golang-jwt/jwt/v4"
gocache "github.com/patrickmn/go-cache"
log "github.com/sirupsen/logrus"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
apiv1 "k8s.io/api/core/v1"
apierr "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/fields"
v1 "k8s.io/client-go/informers/core/v1"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/tools/cache"
)
const (
ConfigMapPolicyCSVKey = "policy.csv"
ConfigMapPolicyDefaultKey = "policy.default"
ConfigMapScopesKey = "scopes"
ConfigMapMatchModeKey = "policy.matchMode"
GlobMatchMode = "glob"
RegexMatchMode = "regex"
defaultRBACSyncPeriod = 10 * time.Minute
)
// CasbinEnforcer represents methods that must be implemented by a Casbin enforces
type CasbinEnforcer interface {
EnableLog(bool)
Enforce(rvals ...interface{}) (bool, error)
LoadPolicy() error
EnableEnforce(bool)
AddFunction(name string, function govaluate.ExpressionFunction)
GetGroupingPolicy() [][]string
}
// Enforcer is a wrapper around an Casbin enforcer that:
// * is backed by a kubernetes config map
// * has a predefined RBAC model
// * supports a built-in policy
// * supports a user-defined policy
// * supports a custom JWT claims enforce function
type Enforcer struct {
lock sync.Mutex
enforcerCache *gocache.Cache
adapter *argocdAdapter
enableLog bool
enabled bool
clientset kubernetes.Interface
namespace string
configmap string
claimsEnforcerFunc ClaimsEnforcerFunc
model model.Model
defaultRole string
matchMode string
}
// cachedEnforcer holds the Casbin enforcer instances and optional custom project policy
type cachedEnforcer struct {
enforcer CasbinEnforcer
policy string
}
func (e *Enforcer) invalidateCache(actions ...func()) {
e.lock.Lock()
defer e.lock.Unlock()
for _, action := range actions {
action()
}
e.enforcerCache.Flush()
}
func (e *Enforcer) getCabinEnforcer(project string, policy string) CasbinEnforcer {
res, err := e.tryGetCabinEnforcer(project, policy)
if err != nil {
panic(err)
}
return res
}
// tryGetCabinEnforcer returns the cached enforcer for the given optional project and project policy.
func (e *Enforcer) tryGetCabinEnforcer(project string, policy string) (CasbinEnforcer, error) {
e.lock.Lock()
defer e.lock.Unlock()
var cached *cachedEnforcer
val, ok := e.enforcerCache.Get(project)
if ok {
if c, ok := val.(*cachedEnforcer); ok && c.policy == policy {
cached = c
}
}
if cached != nil {
return cached.enforcer, nil
}
matchFunc := globMatchFunc
if e.matchMode == RegexMatchMode {
matchFunc = util.RegexMatchFunc
}
var err error
var enforcer CasbinEnforcer
if policy != "" {
if enforcer, err = newEnforcerSafe(matchFunc, e.model, newAdapter(e.adapter.builtinPolicy, e.adapter.userDefinedPolicy, policy)); err != nil {
// fallback to default policy if project policy is invalid
log.Errorf("Failed to load project '%s' policy", project)
enforcer, err = newEnforcerSafe(matchFunc, e.model, e.adapter)
}
} else {
enforcer, err = newEnforcerSafe(matchFunc, e.model, e.adapter)
}
if err != nil {
return nil, err
}
enforcer.AddFunction("globOrRegexMatch", matchFunc)
enforcer.EnableLog(e.enableLog)
enforcer.EnableEnforce(e.enabled)
e.enforcerCache.SetDefault(project, &cachedEnforcer{enforcer: enforcer, policy: policy})
return enforcer, nil
}
// ClaimsEnforcerFunc is func template to enforce a JWT claims. The subject is replaced
type ClaimsEnforcerFunc func(claims jwt.Claims, rvals ...interface{}) bool
func newEnforcerSafe(matchFunction govaluate.ExpressionFunction, params ...interface{}) (e CasbinEnforcer, err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("%v", r)
e = nil
}
}()
enfs, err := casbin.NewCachedEnforcer(params...)
if err != nil {
return nil, err
}
enfs.AddFunction("globOrRegexMatch", matchFunction)
return enfs, nil
}
func NewEnforcer(clientset kubernetes.Interface, namespace, configmap string, claimsEnforcer ClaimsEnforcerFunc) *Enforcer {
adapter := newAdapter("", "", "")
builtInModel := newBuiltInModel()
return &Enforcer{
enforcerCache: gocache.New(time.Hour, time.Hour),
adapter: adapter,
clientset: clientset,
namespace: namespace,
configmap: configmap,
model: builtInModel,
claimsEnforcerFunc: claimsEnforcer,
enabled: true,
}
}
// EnableLog executes casbin.Enforcer functionality.
func (e *Enforcer) EnableLog(s bool) {
e.invalidateCache(func() {
e.enableLog = s
})
}
// EnableEnforce executes casbin.Enforcer functionality and will invalidate cache if required.
func (e *Enforcer) EnableEnforce(s bool) {
e.invalidateCache(func() {
e.enabled = s
})
}
// LoadPolicy executes casbin.Enforcer functionality and will invalidate cache if required.
func (e *Enforcer) LoadPolicy() error {
_, err := e.tryGetCabinEnforcer("", "")
return err
}
// Glob match func
func globMatchFunc(args ...interface{}) (interface{}, error) {
if len(args) < 2 {
return false, nil
}
val, ok := args[0].(string)
if !ok {
return false, nil
}
pattern, ok := args[1].(string)
if !ok {
return false, nil
}
return glob.Match(pattern, val), nil
}
// SetMatchMode set match mode on runtime, glob match or regex match
func (e *Enforcer) SetMatchMode(mode string) {
e.invalidateCache(func() {
if mode == RegexMatchMode {
e.matchMode = RegexMatchMode
} else {
e.matchMode = GlobMatchMode
}
})
}
// SetDefaultRole sets a default role to use during enforcement. Will fall back to this role if
// normal enforcement fails
func (e *Enforcer) SetDefaultRole(roleName string) {
e.defaultRole = roleName
}
// SetClaimsEnforcerFunc sets a claims enforce function during enforcement. The claims enforce function
// can extract claims from JWT token and do the proper enforcement based on user, group or any information
// available in the input parameter list
func (e *Enforcer) SetClaimsEnforcerFunc(claimsEnforcer ClaimsEnforcerFunc) {
e.claimsEnforcerFunc = claimsEnforcer
}
// Enforce is a wrapper around casbin.Enforce to additionally enforce a default role and a custom
// claims function
func (e *Enforcer) Enforce(rvals ...interface{}) bool {
return enforce(e.getCabinEnforcer("", ""), e.defaultRole, e.claimsEnforcerFunc, rvals...)
}
// EnforceErr is a convenience helper to wrap a failed enforcement with a detailed error about the request
func (e *Enforcer) EnforceErr(rvals ...interface{}) error {
if !e.Enforce(rvals...) {
errMsg := "permission denied"
if len(rvals) > 0 {
rvalsStrs := make([]string, len(rvals)-1)
for i, rval := range rvals[1:] {
rvalsStrs[i] = fmt.Sprintf("%s", rval)
}
switch s := rvals[0].(type) {
case jwt.Claims:
claims, err := jwtutil.MapClaims(s)
if err != nil {
break
}
if sub := jwtutil.StringField(claims, "sub"); sub != "" {
rvalsStrs = append(rvalsStrs, fmt.Sprintf("sub: %s", sub))
}
if issuedAtTime, err := jwtutil.IssuedAtTime(claims); err == nil {
rvalsStrs = append(rvalsStrs, fmt.Sprintf("iat: %s", issuedAtTime.Format(time.RFC3339)))
}
}
errMsg = fmt.Sprintf("%s: %s", errMsg, strings.Join(rvalsStrs, ", "))
}
return status.Error(codes.PermissionDenied, errMsg)
}
return nil
}
// EnforceRuntimePolicy enforces a policy defined at run-time which augments the built-in and
// user-defined policy. This allows any explicit denies of the built-in, and user-defined policies
// to override the run-time policy. Runs normal enforcement if run-time policy is empty.
func (e *Enforcer) EnforceRuntimePolicy(project string, policy string, rvals ...interface{}) bool {
enf := e.CreateEnforcerWithRuntimePolicy(project, policy)
return e.EnforceWithCustomEnforcer(enf, rvals...)
}
// CreateEnforcerWithRuntimePolicy creates an enforcer with a policy defined at run-time which augments the built-in and
// user-defined policy. This allows any explicit denies of the built-in, and user-defined policies
// to override the run-time policy. Runs normal enforcement if run-time policy is empty.
func (e *Enforcer) CreateEnforcerWithRuntimePolicy(project string, policy string) CasbinEnforcer {
return e.getCabinEnforcer(project, policy)
}
// EnforceWithCustomEnforcer wraps enforce with an custom enforcer
func (e *Enforcer) EnforceWithCustomEnforcer(enf CasbinEnforcer, rvals ...interface{}) bool {
return enforce(enf, e.defaultRole, e.claimsEnforcerFunc, rvals...)
}
// enforce is a helper to additionally check a default role and invoke a custom claims enforcement function
func enforce(enf CasbinEnforcer, defaultRole string, claimsEnforcerFunc ClaimsEnforcerFunc, rvals ...interface{}) bool {
// check the default role
if defaultRole != "" && len(rvals) >= 2 {
if ok, err := enf.Enforce(append([]interface{}{defaultRole}, rvals[1:]...)...); ok && err == nil {
return true
}
}
if len(rvals) == 0 {
return false
}
// check if subject is jwt.Claims vs. a normal subject string and run custom claims
// enforcement func (if set)
sub := rvals[0]
switch s := sub.(type) {
case string:
// noop
case jwt.Claims:
if claimsEnforcerFunc != nil && claimsEnforcerFunc(s, rvals...) {
return true
}
rvals = append([]interface{}{""}, rvals[1:]...)
default:
rvals = append([]interface{}{""}, rvals[1:]...)
}
ok, err := enf.Enforce(rvals...)
return ok && err == nil
}
// SetBuiltinPolicy sets a built-in policy, which augments any user defined policies
func (e *Enforcer) SetBuiltinPolicy(policy string) error {
e.invalidateCache(func() {
e.adapter.builtinPolicy = policy
})
return e.LoadPolicy()
}
// SetUserPolicy sets a user policy, augmenting the built-in policy
func (e *Enforcer) SetUserPolicy(policy string) error {
e.invalidateCache(func() {
e.adapter.userDefinedPolicy = policy
})
return e.LoadPolicy()
}
// newInformers returns an informer which watches updates on the rbac configmap
func (e *Enforcer) newInformer() cache.SharedIndexInformer {
tweakConfigMap := func(options *metav1.ListOptions) {
cmFieldSelector := fields.ParseSelectorOrDie(fmt.Sprintf("metadata.name=%s", e.configmap))
options.FieldSelector = cmFieldSelector.String()
}
indexers := cache.Indexers{cache.NamespaceIndex: cache.MetaNamespaceIndexFunc}
return v1.NewFilteredConfigMapInformer(e.clientset, e.namespace, defaultRBACSyncPeriod, indexers, tweakConfigMap)
}
// RunPolicyLoader runs the policy loader which watches policy updates from the configmap and reloads them
func (e *Enforcer) RunPolicyLoader(ctx context.Context, onUpdated func(cm *apiv1.ConfigMap) error) error {
cm, err := e.clientset.CoreV1().ConfigMaps(e.namespace).Get(ctx, e.configmap, metav1.GetOptions{})
if err != nil {
if !apierr.IsNotFound(err) {
return err
}
} else {
err = e.syncUpdate(cm, onUpdated)
if err != nil {
return err
}
}
e.runInformer(ctx, onUpdated)
return nil
}
func (e *Enforcer) runInformer(ctx context.Context, onUpdated func(cm *apiv1.ConfigMap) error) {
cmInformer := e.newInformer()
cmInformer.AddEventHandler(
cache.ResourceEventHandlerFuncs{
AddFunc: func(obj interface{}) {
if cm, ok := obj.(*apiv1.ConfigMap); ok {
err := e.syncUpdate(cm, onUpdated)
if err != nil {
log.Error(err)
} else {
log.Infof("RBAC ConfigMap '%s' added", e.configmap)
}
}
},
UpdateFunc: func(old, new interface{}) {
oldCM := old.(*apiv1.ConfigMap)
newCM := new.(*apiv1.ConfigMap)
if oldCM.ResourceVersion == newCM.ResourceVersion {
return
}
err := e.syncUpdate(newCM, onUpdated)
if err != nil {
log.Error(err)
} else {
log.Infof("RBAC ConfigMap '%s' updated", e.configmap)
}
},
},
)
log.Info("Starting rbac config informer")
cmInformer.Run(ctx.Done())
log.Info("rbac configmap informer cancelled")
}
// syncUpdate updates the enforcer
func (e *Enforcer) syncUpdate(cm *apiv1.ConfigMap, onUpdated func(cm *apiv1.ConfigMap) error) error {
e.SetDefaultRole(cm.Data[ConfigMapPolicyDefaultKey])
e.SetMatchMode(cm.Data[ConfigMapMatchModeKey])
policyCSV, ok := cm.Data[ConfigMapPolicyCSVKey]
if !ok {
policyCSV = ""
}
if err := onUpdated(cm); err != nil {
return err
}
return e.SetUserPolicy(policyCSV)
}
// ValidatePolicy verifies a policy string is acceptable to casbin
func ValidatePolicy(policy string) error {
_, err := newEnforcerSafe(globMatchFunc, newBuiltInModel(), newAdapter("", "", policy))
if err != nil {
return fmt.Errorf("policy syntax error: %s", policy)
}
return nil
}
// newBuiltInModel is a helper to return a brand new casbin model from the built-in model string.
// This is needed because it is not safe to re-use the same casbin Model when instantiating new
// casbin enforcers.
func newBuiltInModel() model.Model {
m, err := model.NewModelFromString(assets.ModelConf)
if err != nil {
panic(err)
}
return m
}
// Casbin adapter which satisfies persist.Adapter interface
type argocdAdapter struct {
builtinPolicy string
userDefinedPolicy string
runtimePolicy string
}
func newAdapter(builtinPolicy, userDefinedPolicy, runtimePolicy string) *argocdAdapter {
return &argocdAdapter{
builtinPolicy: builtinPolicy,
userDefinedPolicy: userDefinedPolicy,
runtimePolicy: runtimePolicy,
}
}
func (a *argocdAdapter) LoadPolicy(model model.Model) error {
for _, policyStr := range []string{a.builtinPolicy, a.userDefinedPolicy, a.runtimePolicy} {
for _, line := range strings.Split(policyStr, "\n") {
if err := loadPolicyLine(strings.TrimSpace(line), model); err != nil {
return err
}
}
}
return nil
}
// The modified version of LoadPolicyLine function defined in "persist" package of github.com/casbin/casbin.
// Uses CVS parser to correctly handle quotes in policy line.
func loadPolicyLine(line string, model model.Model) error {
if line == "" || strings.HasPrefix(line, "#") {
return nil
}
reader := csv.NewReader(strings.NewReader(line))
reader.TrimLeadingSpace = true
tokens, err := reader.Read()
if err != nil {
return err
}
if len(tokens) < 2 || len(tokens[0]) < 1 {
return fmt.Errorf("invalid RBAC policy: %s", line)
}
key := tokens[0]
sec := key[:1]
if _, ok := model[sec]; !ok {
return fmt.Errorf("invalid RBAC policy: %s", line)
}
if _, ok := model[sec][key]; !ok {
return fmt.Errorf("invalid RBAC policy: %s", line)
}
model[sec][key].Policy = append(model[sec][key].Policy, tokens[1:])
return nil
}
func (a *argocdAdapter) SavePolicy(model model.Model) error {
return errors.New("not implemented")
}
func (a *argocdAdapter) AddPolicy(sec string, ptype string, rule []string) error {
return errors.New("not implemented")
}
func (a *argocdAdapter) RemovePolicy(sec string, ptype string, rule []string) error {
return errors.New("not implemented")
}
func (a *argocdAdapter) RemoveFilteredPolicy(sec string, ptype string, fieldIndex int, fieldValues ...string) error {
return errors.New("not implemented")
}