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First ACL implementation

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This commit is contained in:
Alex 2020-01-26 18:42:04 +01:00
parent 2ad9bce75c
commit 82402749e6
3 changed files with 320 additions and 102 deletions
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131
acl.go Normal file
View file

@ -0,0 +1,131 @@
package main
import (
"fmt"
"path"
"strings"
)
type Login struct {
user string
groups []string
}
type ACL []ACLEntry
type ACLEntry struct {
// The authenticated user (or ANONYMOUS if not authenticated) must match this string
user string
// For each of this groups, the authenticated user must belong to one group that matches
reqGroups []string
// The action requested must match one of these strings
actions []string
// The requested target must match this string. The special word SELF is replaced in the pattern by the user's dn before matching
target string
// All attributes requested must match one of these patterns
attributes []string
// All attributes requested must not match any of these patterns
exclAttributes []string
}
func splitNoEmpty(s string) []string {
if len(s) == 0 {
return []string{}
}
return strings.Split(s, " ")
}
func ParseACL(def []string) (ACL, error) {
acl := []ACLEntry{}
for _, item := range def {
parts := strings.Split(item, ":")
if len(parts) != 5 {
return nil, fmt.Errorf("Invalid ACL entry: %s", item)
}
attr, exclAttr := []string{}, []string{}
for _, s := range splitNoEmpty(parts[4]) {
if s[0] == '!' {
exclAttr = append(exclAttr, s)
} else {
attr = append(attr, s)
}
}
item_def := ACLEntry{
user: parts[0],
reqGroups: splitNoEmpty(parts[1]),
actions: splitNoEmpty(parts[2]),
target: parts[3],
attributes: attr,
exclAttributes: exclAttr,
}
acl = append(acl, item_def)
}
return acl, nil
}
func (acl ACL) Check(login *Login, action string, target string, attributes []string) bool {
for _, item := range acl {
if item.Check(login, action, target, attributes) {
return true
}
}
return false
}
func (entry *ACLEntry) Check(login *Login, action string, target string, attributes []string) bool {
if !match(entry.user, login.user) {
return false
}
for _, grp := range entry.reqGroups {
if !matchAny(grp, login.groups) {
return false
}
}
rule_target_with_self := strings.ReplaceAll(entry.target, "SELF", login.user)
if !match(rule_target_with_self, target) {
return false
}
if !anyMatch(entry.actions, action) {
return false
}
for _, attrib := range attributes {
if !anyMatch(entry.attributes, attrib) {
return false
}
}
for _, exclAttr := range entry.exclAttributes {
if matchAny(exclAttr, attributes) {
return false
}
}
return true
}
func match(pattern string, val string) bool {
rv, err := path.Match(strings.ToLower(pattern), strings.ToLower(val))
return err == nil && rv
}
func matchAny(pattern string, vals []string) bool {
for _, val := range vals {
if match(pattern, val) {
return true
}
}
return false
}
func anyMatch(patterns []string, val string) bool {
for _, pattern := range patterns {
if match(pattern, val) {
return true
}
}
return false
}

188
main.go
View file

@ -3,6 +3,7 @@ package main
// @FIXME: Implement a real permission system: limit read/write scope/attributes, possibly based on group membership
// @FIXME: Implement missing search filters (in applyFilter)
// @FIXME: Add an initial prefix to the consul key value
// @FIXME: Add TLS connections
import (
"encoding/base64"
@ -20,100 +21,9 @@ import (
message "github.com/vjeantet/goldap/message"
)
func dnToConsul(dn string) (string, error) {
if strings.Contains(dn, "/") {
return "", fmt.Errorf("DN %s contains a /", dn)
}
rdns := strings.Split(dn, ",")
// Reverse rdns
for i, j := 0, len(rdns)-1; i < j; i, j = i+1, j-1 {
rdns[i], rdns[j] = rdns[j], rdns[i]
}
return strings.Join(rdns, "/"), nil
}
func consulToDN(key string) (string, string) {
path := strings.Split(key, "/")
dn := ""
for _, cpath := range path {
if cpath == "" {
continue
}
kv := strings.Split(cpath, "=")
if len(kv) == 2 && kv[0] == "attribute" {
return dn, kv[1]
}
if dn != "" {
dn = "," + dn
}
dn = cpath + dn
}
panic("Consul key " + key + " does not end with attribute=something")
}
func parseValue(value []byte) ([]string, error) {
val := []string{}
err := json.Unmarshal(value, &val)
if err == nil {
return val, nil
}
val2 := ""
err = json.Unmarshal(value, &val2)
if err == nil {
return []string{val2}, nil
}
return nil, fmt.Errorf("Not a string or list of strings: %s", value)
}
func parseConsulResult(data []*consul.KVPair) (map[string]Entry, error) {
aggregator := map[string]Entry{}
for _, kv := range data {
log.Printf("(parseConsulResult) %s %s", kv.Key, string(kv.Value))
dn, attr := consulToDN(kv.Key)
if _, exists := aggregator[dn]; !exists {
aggregator[dn] = Entry{}
}
value, err := parseValue(kv.Value)
if err != nil {
return nil, err
}
aggregator[dn][attr] = value
}
return aggregator, nil
}
type DNComponent struct {
Type string
Value string
}
func parseDN(dn string) ([]DNComponent, error) {
rdns := strings.Split(dn, ",")
ret := []DNComponent{}
for _, rdn := range rdns {
splits := strings.Split(rdn, "=")
if len(splits) != 2 {
return nil, fmt.Errorf("Wrong DN component: %s (expected type=value)", rdn)
}
ret = append(ret, DNComponent{
Type: splits[0],
Value: splits[1],
})
}
return ret, nil
}
type Config struct {
Suffix string
Acl ACL
}
type Server struct {
@ -122,7 +32,7 @@ type Server struct {
}
type State struct {
bindDn string
login Login
}
type Entry map[string][]string
@ -138,9 +48,29 @@ func main() {
}
kv := client.KV()
aclStr := []string{
// Anybody (before binding) can bind to an entity under ou=users,dc=gobottin,dc=eu
"ANONYMOUS::bind:*,ou=users,dc=gobottin,dc=eu:",
// Anybody (before binding) can bind to the specific admin entity
"ANONYMOUS::bind:cn=admin,dc=gobottin,dc=eu:",
// Anybody who is logged in can read anything that is not a userpassword attribute
"*,dc=gobottin,dc=eu::read:*:* !userpassword",
// Anybody can read and modify anything from their own entry
"*::read modify:SELF:*",
// The admin can add, modify, delete anything
"cn=admin,dc=gobottin,dc=eu::add modify delete:*:*",
// Members of the admin group can add, modify, delete anything
"*:cn=admin,ou=groups,dc=gobottin,dc=eu:add modify delete:*:*",
}
acl, err := ParseACL(aclStr)
if err != nil {
panic(err)
}
// TODO read config from somewhere
config := Config{
Suffix: "dc=gobottin,dc=eu",
Acl: acl,
}
gobottin := Server{config: config, kv: kv}
@ -152,7 +82,12 @@ func main() {
//Create a new LDAP Server
ldapserver := ldap.NewServer()
ldapserver.NewUserState = func() ldap.UserState {
return &State{}
return &State{
login: Login{
user: "ANONYMOUS",
groups: []string{},
},
}
}
routes := ldap.NewRouteMux()
@ -328,11 +263,16 @@ func (server *Server) handleBind(s ldap.UserState, w ldap.ResponseWriter, m *lda
}
func (server *Server) handleBindInternal(state *State, r *message.BindRequest) (int, error) {
// Check permissions
if !server.config.Acl.Check(&state.login, "bind", string(r.Name()), []string{}) {
return ldap.LDAPResultInsufficientAccessRights, nil
}
// Try to retrieve password and check for match
passwd, err := server.getAttribute(string(r.Name()), "userpassword")
if err != nil {
return ldap.LDAPResultOperationsError, err
}
if passwd == nil {
return ldap.LDAPResultNoSuchObject, nil
}
@ -340,7 +280,14 @@ func (server *Server) handleBindInternal(state *State, r *message.BindRequest) (
for _, hash := range passwd {
valid := SSHAMatches(hash, []byte(r.AuthenticationSimple()))
if valid {
state.bindDn = string(r.Name())
groups, err := server.getAttribute(string(r.Name()), "memberOf")
if err != nil {
return ldap.LDAPResultOperationsError, err
}
state.login = Login{
user: string(r.Name()),
groups: groups,
}
return ldap.LDAPResultSuccess, nil
}
}
@ -368,7 +315,9 @@ func (server *Server) handleSearchInternal(state *State, w ldap.ResponseWriter,
log.Printf("Request Attributes=%s", r.Attributes())
log.Printf("Request TimeLimit=%d", r.TimeLimit().Int())
// TODO check authorizations
if !server.config.Acl.Check(&state.login, "read", string(r.BaseObject()), []string{}) {
return ldap.LDAPResultInsufficientAccessRights, fmt.Errorf("Please specify a base object on which you have read rights")
}
baseObject, err := server.checkSuffix(string(r.BaseObject()), true)
if err != nil {
@ -392,7 +341,7 @@ func (server *Server) handleSearchInternal(state *State, w ldap.ResponseWriter,
log.Printf("%#v", entries)
for dn, entry := range entries {
// TODO filter out if no permission to read this
// Filter out if we don't match requested filter
matched, err := applyFilter(entry, r.Filter())
if err != nil {
return ldap.LDAPResultUnwillingToPerform, err
@ -401,6 +350,11 @@ func (server *Server) handleSearchInternal(state *State, w ldap.ResponseWriter,
continue
}
// Filter out if user is not allowed to read this
if !server.config.Acl.Check(&state.login, "read", dn, []string{}) {
continue
}
e := ldap.NewSearchResultEntry(dn)
for attr, val := range entry {
// If attribute is not in request, exclude it from returned entry
@ -416,6 +370,10 @@ func (server *Server) handleSearchInternal(state *State, w ldap.ResponseWriter,
continue
}
}
// If we are not allowed to read attribute, exclude it from returned entry
if !server.config.Acl.Check(&state.login, "read", dn, []string{attr}) {
continue
}
// Send result
for _, v := range val {
e.AddAttribute(message.AttributeDescription(attr),
@ -507,6 +465,16 @@ func (server *Server) handleAddInternal(state *State, r *message.AddRequest) (in
return ldap.LDAPResultInvalidDNSyntax, err
}
// Check permissions
attrListStr := []string{}
for _, attribute := range r.Attributes() {
attrListStr = append(attrListStr, string(attribute.Type_()))
}
if !server.config.Acl.Check(&state.login, "add", dn, attrListStr) {
return ldap.LDAPResultInsufficientAccessRights, nil
}
// Check that object does not already exist
exists, err := server.objectExists(dn)
if err != nil {
return ldap.LDAPResultOperationsError, err
@ -515,8 +483,9 @@ func (server *Server) handleAddInternal(state *State, r *message.AddRequest) (in
return ldap.LDAPResultEntryAlreadyExists, nil
}
// TODO check permissions
// Add object
// If adding a group, track of who the members will be so that their memberOf field can be updated later
var members []string = nil
entry := Entry{}
@ -617,8 +586,12 @@ func (server *Server) handleCompareInternal(state *State, r *message.CompareRequ
return ldap.LDAPResultInvalidDNSyntax, err
}
// TODO check user for permissions to read dn
// Check permissions
if !server.config.Acl.Check(&state.login, dn, "read", []string{attr}) {
return ldap.LDAPResultInsufficientAccessRights, nil
}
// Do query
exists, err := server.objectExists(dn)
if err != nil {
return ldap.LDAPResultOperationsError, err
@ -662,7 +635,10 @@ func (server *Server) handleDeleteInternal(state *State, r *message.DelRequest)
return ldap.LDAPResultInvalidDNSyntax, err
}
// TODO check user for permissions to write dn
// Check for delete permission
if !server.config.Acl.Check(&state.login, "delete", dn, []string{}) {
return ldap.LDAPResultInsufficientAccessRights, nil
}
// Check that this LDAP entry exists and has no children
path, err := dnToConsul(dn)
@ -746,7 +722,10 @@ func (server *Server) handleModifyInternal(state *State, r *message.ModifyReques
return ldap.LDAPResultInvalidDNSyntax, err
}
// TODO check user for permissions to write dn
// First permission check with no particular attributes
if !server.config.Acl.Check(&state.login, "modify", dn, []string{}) {
return ldap.LDAPResultInsufficientAccessRights, nil
}
// Retrieve previous values (by the way, check object exists)
path, err := dnToConsul(dn)
@ -785,6 +764,11 @@ func (server *Server) handleModifyInternal(state *State, r *message.ModifyReques
attr := string(change.Modification().Type_())
values := change.Modification().Vals()
// Check for permission to modify this attribute
if !server.config.Acl.Check(&state.login, "modify", dn, []string{attr}) {
return ldap.LDAPResultInsufficientAccessRights, nil
}
if change.Operation() == ldap.ModifyRequestChangeOperationAdd {
newEntry[attr] = prevEntry[attr]
for _, val := range values {

103
util.go Normal file
View file

@ -0,0 +1,103 @@
package main
import (
"encoding/json"
"fmt"
"log"
"strings"
consul "github.com/hashicorp/consul/api"
)
func dnToConsul(dn string) (string, error) {
if strings.Contains(dn, "/") {
return "", fmt.Errorf("DN %s contains a /", dn)
}
rdns := strings.Split(dn, ",")
// Reverse rdns
for i, j := 0, len(rdns)-1; i < j; i, j = i+1, j-1 {
rdns[i], rdns[j] = rdns[j], rdns[i]
}
return strings.Join(rdns, "/"), nil
}
func consulToDN(key string) (string, string) {
path := strings.Split(key, "/")
dn := ""
for _, cpath := range path {
if cpath == "" {
continue
}
kv := strings.Split(cpath, "=")
if len(kv) == 2 && kv[0] == "attribute" {
return dn, kv[1]
}
if dn != "" {
dn = "," + dn
}
dn = cpath + dn
}
log.Printf("Consul key %s does not end with attribute=something", key)
panic("TODO don't panic handle this")
}
func parseValue(value []byte) ([]string, error) {
val := []string{}
err := json.Unmarshal(value, &val)
if err == nil {
return val, nil
}
val2 := ""
err = json.Unmarshal(value, &val2)
if err == nil {
return []string{val2}, nil
}
return nil, fmt.Errorf("Not a string or list of strings: %s", value)
}
func parseConsulResult(data []*consul.KVPair) (map[string]Entry, error) {
aggregator := map[string]Entry{}
for _, kv := range data {
log.Printf("(parseConsulResult) %s %s", kv.Key, string(kv.Value))
dn, attr := consulToDN(kv.Key)
if _, exists := aggregator[dn]; !exists {
aggregator[dn] = Entry{}
}
value, err := parseValue(kv.Value)
if err != nil {
return nil, err
}
aggregator[dn][attr] = value
}
return aggregator, nil
}
type DNComponent struct {
Type string
Value string
}
func parseDN(dn string) ([]DNComponent, error) {
rdns := strings.Split(dn, ",")
ret := []DNComponent{}
for _, rdn := range rdns {
splits := strings.Split(rdn, "=")
if len(splits) != 2 {
return nil, fmt.Errorf("Wrong DN component: %s (expected type=value)", rdn)
}
ret = append(ret, DNComponent{
Type: splits[0],
Value: splits[1],
})
}
return ret, nil
}