package acl import ( "github.com/armon/go-radix" ) var ( // allowAll is a singleton policy which allows all // non-management actions allowAll ACL // denyAll is a singleton policy which denies all actions denyAll ACL // manageAll is a singleton policy which allows all // actions, including management manageAll ACL ) func init() { // Setup the singletons allowAll = &StaticACL{ allowManage: false, defaultAllow: true, } denyAll = &StaticACL{ allowManage: false, defaultAllow: false, } manageAll = &StaticACL{ allowManage: true, defaultAllow: true, } } // ACL is the interface for policy enforcement. type ACL interface { // KeyRead checks for permission to read a given key KeyRead(string) bool // KeyWrite checks for permission to write a given key KeyWrite(string) bool // KeyWritePrefix checks for permission to write to an // entire key prefix. This means there must be no sub-policies // that deny a write. KeyWritePrefix(string) bool // ACLList checks for permission to list all the ACLs ACLList() bool // ACLModify checks for permission to manipulate ACLs ACLModify() bool } // StaticACL is used to implement a base ACL policy. It either // allows or denies all requests. This can be used as a parent // ACL to act in a blacklist or whitelist mode. type StaticACL struct { allowManage bool defaultAllow bool } func (s *StaticACL) KeyRead(string) bool { return s.defaultAllow } func (s *StaticACL) KeyWrite(string) bool { return s.defaultAllow } func (s *StaticACL) KeyWritePrefix(string) bool { return s.defaultAllow } func (s *StaticACL) ACLList() bool { return s.allowManage } func (s *StaticACL) ACLModify() bool { return s.allowManage } // AllowAll returns an ACL rule that allows all operations func AllowAll() ACL { return allowAll } // DenyAll returns an ACL rule that denies all operations func DenyAll() ACL { return denyAll } // ManageAll returns an ACL rule that can manage all resources func ManageAll() ACL { return manageAll } // RootACL returns a possible ACL if the ID matches a root policy func RootACL(id string) ACL { switch id { case "allow": return allowAll case "deny": return denyAll case "manage": return manageAll default: return nil } } // PolicyACL is used to wrap a set of ACL policies to provide // the ACL interface. type PolicyACL struct { // parent is used to resolve policy if we have // no matching rule. parent ACL // keyRules contains the key policies keyRules *radix.Tree } // New is used to construct a policy based ACL from a set of policies // and a parent policy to resolve missing cases. func New(parent ACL, policy *Policy) (*PolicyACL, error) { p := &PolicyACL{ parent: parent, keyRules: radix.New(), } // Load the key policy for _, kp := range policy.Keys { p.keyRules.Insert(kp.Prefix, kp.Policy) } return p, nil } // KeyRead returns if a key is allowed to be read func (p *PolicyACL) KeyRead(key string) bool { // Look for a matching rule _, rule, ok := p.keyRules.LongestPrefix(key) if ok { switch rule.(string) { case KeyPolicyRead: return true case KeyPolicyWrite: return true default: return false } } // No matching rule, use the parent. return p.parent.KeyRead(key) } // KeyWrite returns if a key is allowed to be written func (p *PolicyACL) KeyWrite(key string) bool { // Look for a matching rule _, rule, ok := p.keyRules.LongestPrefix(key) if ok { switch rule.(string) { case KeyPolicyWrite: return true default: return false } } // No matching rule, use the parent. return p.parent.KeyWrite(key) } // KeyWritePrefix returns if a prefix is allowed to be written func (p *PolicyACL) KeyWritePrefix(prefix string) bool { // Look for a matching rule that denies _, rule, ok := p.keyRules.LongestPrefix(prefix) if ok && rule.(string) != KeyPolicyWrite { return false } // Look if any of our children have a deny policy deny := false p.keyRules.WalkPrefix(prefix, func(path string, rule interface{}) bool { // We have a rule to prevent a write in a sub-directory! if rule.(string) != KeyPolicyWrite { deny = true return true } return false }) // Deny the write if any sub-rules may be violated if deny { return false } // If we had a matching rule, done if ok { return true } // No matching rule, use the parent. return p.parent.KeyWritePrefix(prefix) } // ACLList checks if listing of ACLs is allowed func (p *PolicyACL) ACLList() bool { return p.parent.ACLList() } // ACLModify checks if modification of ACLs is allowed func (p *PolicyACL) ACLModify() bool { return p.parent.ACLModify() }