open-consul/agent/consul/acl_authmethod.go

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package consul
import (
"fmt"
"github.com/hashicorp/consul/agent/consul/authmethod"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/go-bexpr"
// register this as a builtin auth method
_ "github.com/hashicorp/consul/agent/consul/authmethod/kubeauth"
)
type authMethodValidatorEntry struct {
Validator authmethod.Validator
ModifyIndex uint64 // the raft index when this last changed
}
// loadAuthMethodValidator returns an authmethod.Validator for the given auth
// method configuration. If the cache is up to date as-of the provided index
// then the cached version is returned, otherwise a new validator is created
// and cached.
func (s *Server) loadAuthMethodValidator(idx uint64, method *structs.ACLAuthMethod) (authmethod.Validator, error) {
if prevIdx, v, ok := s.getCachedAuthMethodValidator(method.Name); ok && idx <= prevIdx {
return v, nil
}
v, err := authmethod.NewValidator(method)
if err != nil {
return nil, fmt.Errorf("auth method validator for %q could not be initialized: %v", method.Name, err)
}
v = s.getOrReplaceAuthMethodValidator(method.Name, idx, v)
return v, nil
}
// getCachedAuthMethodValidator returns an AuthMethodValidator for
// the given name exclusively from the cache. If one is not found in the cache
// nil is returned.
func (s *Server) getCachedAuthMethodValidator(name string) (uint64, authmethod.Validator, bool) {
s.aclAuthMethodValidatorLock.RLock()
defer s.aclAuthMethodValidatorLock.RUnlock()
if s.aclAuthMethodValidators != nil {
v, ok := s.aclAuthMethodValidators[name]
if ok {
return v.ModifyIndex, v.Validator, true
}
}
return 0, nil, false
}
// getOrReplaceAuthMethodValidator updates the cached validator with the
// provided one UNLESS it has been updated by another goroutine in which case
// the updated one is returned.
func (s *Server) getOrReplaceAuthMethodValidator(name string, idx uint64, v authmethod.Validator) authmethod.Validator {
s.aclAuthMethodValidatorLock.Lock()
defer s.aclAuthMethodValidatorLock.Unlock()
if s.aclAuthMethodValidators == nil {
s.aclAuthMethodValidators = make(map[string]*authMethodValidatorEntry)
}
prev, ok := s.aclAuthMethodValidators[name]
if ok {
if prev.ModifyIndex >= idx {
return prev.Validator
}
}
s.logger.Printf("[DEBUG] acl: updating cached auth method validator for %q", name)
s.aclAuthMethodValidators[name] = &authMethodValidatorEntry{
Validator: v,
ModifyIndex: idx,
}
return v
}
// purgeAuthMethodValidators resets the cache of validators.
func (s *Server) purgeAuthMethodValidators() {
s.aclAuthMethodValidatorLock.Lock()
s.aclAuthMethodValidators = make(map[string]*authMethodValidatorEntry)
s.aclAuthMethodValidatorLock.Unlock()
}
// evaluateRoleBindings evaluates all current binding rules associated with the
// given auth method against the verified data returned from the authentication
// process.
//
// A list of role links and service identities are returned.
func (s *Server) evaluateRoleBindings(
validator authmethod.Validator,
verifiedFields map[string]string,
) ([]*structs.ACLServiceIdentity, []structs.ACLTokenRoleLink, error) {
// Only fetch rules that are relevant for this method.
_, rules, err := s.fsm.State().ACLBindingRuleList(nil, validator.Name())
if err != nil {
return nil, nil, err
} else if len(rules) == 0 {
return nil, nil, nil
}
// Convert the fields into something suitable for go-bexpr.
selectableVars := validator.MakeFieldMapSelectable(verifiedFields)
// Find all binding rules that match the provided fields.
var matchingRules []*structs.ACLBindingRule
for _, rule := range rules {
if doesBindingRuleMatch(rule, selectableVars) {
matchingRules = append(matchingRules, rule)
}
}
if len(matchingRules) == 0 {
return nil, nil, nil
}
// For all matching rules compute the attributes of a token.
var (
roleLinks []structs.ACLTokenRoleLink
serviceIdentities []*structs.ACLServiceIdentity
)
for _, rule := range matchingRules {
bindName, valid, err := computeBindingRuleBindName(rule.BindType, rule.BindName, verifiedFields)
if err != nil {
return nil, nil, fmt.Errorf("cannot compute %q bind name for bind target: %v", rule.BindType, err)
} else if !valid {
return nil, nil, fmt.Errorf("computed %q bind name for bind target is invalid: %q", rule.BindType, bindName)
}
switch rule.BindType {
case structs.BindingRuleBindTypeService:
serviceIdentities = append(serviceIdentities, &structs.ACLServiceIdentity{
ServiceName: bindName,
})
case structs.BindingRuleBindTypeRole:
_, role, err := s.fsm.State().ACLRoleGetByName(nil, bindName)
if err != nil {
return nil, nil, err
}
if role != nil {
roleLinks = append(roleLinks, structs.ACLTokenRoleLink{
ID: role.ID,
})
}
default:
// skip unknown bind type; don't grant privileges
}
}
return serviceIdentities, roleLinks, nil
}
// doesBindingRuleMatch checks that a single binding rule matches the provided
// vars.
func doesBindingRuleMatch(rule *structs.ACLBindingRule, selectableVars interface{}) bool {
if rule.Selector == "" {
return true // catch-all
}
eval, err := bexpr.CreateEvaluatorForType(rule.Selector, nil, selectableVars)
if err != nil {
return false // fails to match if selector is invalid
}
result, err := eval.Evaluate(selectableVars)
if err != nil {
return false // fails to match if evaluation fails
}
return result
}