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dex/connector/ldap/ldap.go
Eng Zer Jun f0186ff265
refactor: move from io/ioutil to io and os package
The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
2021-09-17 14:12:39 +08:00

633 lines
19 KiB
Go

// Package ldap implements strategies for authenticating using the LDAP protocol.
package ldap
import (
"context"
"crypto/tls"
"crypto/x509"
"encoding/json"
"fmt"
"net"
"os"
"github.com/go-ldap/ldap/v3"
"github.com/dexidp/dex/connector"
"github.com/dexidp/dex/pkg/log"
)
// Config holds the configuration parameters for the LDAP connector. The LDAP
// connectors require executing two queries, the first to find the user based on
// the username and password given to the connector. The second to use the user
// entry to search for groups.
//
// An example config:
//
// type: ldap
// config:
// host: ldap.example.com:636
// # The following field is required if using port 389.
// # insecureNoSSL: true
// rootCA: /etc/dex/ldap.ca
// bindDN: uid=serviceaccount,cn=users,dc=example,dc=com
// bindPW: password
// userSearch:
// # Would translate to the query "(&(objectClass=person)(uid=<username>))"
// baseDN: cn=users,dc=example,dc=com
// filter: "(objectClass=person)"
// username: uid
// idAttr: uid
// emailAttr: mail
// nameAttr: name
// preferredUsernameAttr: uid
// groupSearch:
// # Would translate to the separate query per user matcher pair and aggregate results into a single group list:
// # "(&(|(objectClass=posixGroup)(objectClass=groupOfNames))(memberUid=<user uid>))"
// # "(&(|(objectClass=posixGroup)(objectClass=groupOfNames))(member=<user DN>))"
// baseDN: cn=groups,dc=example,dc=com
// filter: "(|(objectClass=posixGroup)(objectClass=groupOfNames))"
// userMatchers:
// - userAttr: uid
// groupAttr: memberUid
// # Use if full DN is needed and not available as any other attribute
// # Will only work if "DN" attribute does not exist in the record:
// - userAttr: DN
// groupAttr: member
// nameAttr: name
//
// UserMatcher holds information about user and group matching.
type UserMatcher struct {
UserAttr string `json:"userAttr"`
GroupAttr string `json:"groupAttr"`
}
// Config holds configuration options for LDAP logins.
type Config struct {
// The host and optional port of the LDAP server. If port isn't supplied, it will be
// guessed based on the TLS configuration. 389 or 636.
Host string `json:"host"`
// Required if LDAP host does not use TLS.
InsecureNoSSL bool `json:"insecureNoSSL"`
// Don't verify the CA.
InsecureSkipVerify bool `json:"insecureSkipVerify"`
// Connect to the insecure port then issue a StartTLS command to negotiate a
// secure connection. If unsupplied secure connections will use the LDAPS
// protocol.
StartTLS bool `json:"startTLS"`
// Path to a trusted root certificate file.
RootCA string `json:"rootCA"`
// Path to a client cert file generated by rootCA.
ClientCert string `json:"clientCert"`
// Path to a client private key file generated by rootCA.
ClientKey string `json:"clientKey"`
// Base64 encoded PEM data containing root CAs.
RootCAData []byte `json:"rootCAData"`
// BindDN and BindPW for an application service account. The connector uses these
// credentials to search for users and groups.
BindDN string `json:"bindDN"`
BindPW string `json:"bindPW"`
// UsernamePrompt allows users to override the username attribute (displayed
// in the username/password prompt). If unset, the handler will use
// "Username".
UsernamePrompt string `json:"usernamePrompt"`
// User entry search configuration.
UserSearch struct {
// BaseDN to start the search from. For example "cn=users,dc=example,dc=com"
BaseDN string `json:"baseDN"`
// Optional filter to apply when searching the directory. For example "(objectClass=person)"
Filter string `json:"filter"`
// Attribute to match against the inputted username. This will be translated and combined
// with the other filter as "(<attr>=<username>)".
Username string `json:"username"`
// Can either be:
// * "sub" - search the whole sub tree
// * "one" - only search one level
Scope string `json:"scope"`
// A mapping of attributes on the user entry to claims.
IDAttr string `json:"idAttr"` // Defaults to "uid"
EmailAttr string `json:"emailAttr"` // Defaults to "mail"
NameAttr string `json:"nameAttr"` // No default.
PreferredUsernameAttrAttr string `json:"preferredUsernameAttr"` // No default.
// If this is set, the email claim of the id token will be constructed from the idAttr and
// value of emailSuffix. This should not include the @ character.
EmailSuffix string `json:"emailSuffix"` // No default.
} `json:"userSearch"`
// Group search configuration.
GroupSearch struct {
// BaseDN to start the search from. For example "cn=groups,dc=example,dc=com"
BaseDN string `json:"baseDN"`
// Optional filter to apply when searching the directory. For example "(objectClass=posixGroup)"
Filter string `json:"filter"`
Scope string `json:"scope"` // Defaults to "sub"
// DEPRECATED config options. Those are left for backward compatibility.
// See "UserMatchers" below for the current group to user matching implementation
// TODO: should be eventually removed from the code
UserAttr string `json:"userAttr"`
GroupAttr string `json:"groupAttr"`
// Array of the field pairs used to match a user to a group.
// See the "UserMatcher" struct for the exact field names
//
// Each pair adds an additional requirement to the filter that an attribute in the group
// match the user's attribute value. For example that the "members" attribute of
// a group matches the "uid" of the user. The exact filter being added is:
//
// (userMatchers[n].<groupAttr>=userMatchers[n].<userAttr value>)
//
UserMatchers []UserMatcher `json:"userMatchers"`
// The attribute of the group that represents its name.
NameAttr string `json:"nameAttr"`
} `json:"groupSearch"`
}
func scopeString(i int) string {
switch i {
case ldap.ScopeBaseObject:
return "base"
case ldap.ScopeSingleLevel:
return "one"
case ldap.ScopeWholeSubtree:
return "sub"
default:
return ""
}
}
func parseScope(s string) (int, bool) {
// NOTE(ericchiang): ScopeBaseObject doesn't really make sense for us because we
// never know the user's or group's DN.
switch s {
case "", "sub":
return ldap.ScopeWholeSubtree, true
case "one":
return ldap.ScopeSingleLevel, true
}
return 0, false
}
// Build a list of group attr name to user attr value matchers.
// Function exists here to allow backward compatibility between old and new
// group to user matching implementations.
// See "Config.GroupSearch.UserMatchers" comments for the details
func (c *ldapConnector) userMatchers() []UserMatcher {
if len(c.GroupSearch.UserMatchers) > 0 && c.GroupSearch.UserMatchers[0].UserAttr != "" {
return c.GroupSearch.UserMatchers
}
return []UserMatcher{
{
UserAttr: c.GroupSearch.UserAttr,
GroupAttr: c.GroupSearch.GroupAttr,
},
}
}
// Open returns an authentication strategy using LDAP.
func (c *Config) Open(id string, logger log.Logger) (connector.Connector, error) {
conn, err := c.OpenConnector(logger)
if err != nil {
return nil, err
}
return connector.Connector(conn), nil
}
type refreshData struct {
Username string `json:"username"`
Entry ldap.Entry `json:"entry"`
}
// OpenConnector is the same as Open but returns a type with all implemented connector interfaces.
func (c *Config) OpenConnector(logger log.Logger) (interface {
connector.Connector
connector.PasswordConnector
connector.RefreshConnector
}, error) {
return c.openConnector(logger)
}
func (c *Config) openConnector(logger log.Logger) (*ldapConnector, error) {
requiredFields := []struct {
name string
val string
}{
{"host", c.Host},
{"userSearch.baseDN", c.UserSearch.BaseDN},
{"userSearch.username", c.UserSearch.Username},
}
for _, field := range requiredFields {
if field.val == "" {
return nil, fmt.Errorf("ldap: missing required field %q", field.name)
}
}
var (
host string
err error
)
if host, _, err = net.SplitHostPort(c.Host); err != nil {
host = c.Host
if c.InsecureNoSSL {
c.Host += ":389"
} else {
c.Host += ":636"
}
}
tlsConfig := &tls.Config{ServerName: host, InsecureSkipVerify: c.InsecureSkipVerify}
if c.RootCA != "" || len(c.RootCAData) != 0 {
data := c.RootCAData
if len(data) == 0 {
var err error
if data, err = os.ReadFile(c.RootCA); err != nil {
return nil, fmt.Errorf("ldap: read ca file: %v", err)
}
}
rootCAs := x509.NewCertPool()
if !rootCAs.AppendCertsFromPEM(data) {
return nil, fmt.Errorf("ldap: no certs found in ca file")
}
tlsConfig.RootCAs = rootCAs
}
if c.ClientKey != "" && c.ClientCert != "" {
cert, err := tls.LoadX509KeyPair(c.ClientCert, c.ClientKey)
if err != nil {
return nil, fmt.Errorf("ldap: load client cert failed: %v", err)
}
tlsConfig.Certificates = append(tlsConfig.Certificates, cert)
}
userSearchScope, ok := parseScope(c.UserSearch.Scope)
if !ok {
return nil, fmt.Errorf("userSearch.Scope unknown value %q", c.UserSearch.Scope)
}
groupSearchScope, ok := parseScope(c.GroupSearch.Scope)
if !ok {
return nil, fmt.Errorf("groupSearch.Scope unknown value %q", c.GroupSearch.Scope)
}
return &ldapConnector{*c, userSearchScope, groupSearchScope, tlsConfig, logger}, nil
}
type ldapConnector struct {
Config
userSearchScope int
groupSearchScope int
tlsConfig *tls.Config
logger log.Logger
}
var (
_ connector.PasswordConnector = (*ldapConnector)(nil)
_ connector.RefreshConnector = (*ldapConnector)(nil)
)
// do initializes a connection to the LDAP directory and passes it to the
// provided function. It then performs appropriate teardown or reuse before
// returning.
func (c *ldapConnector) do(_ context.Context, f func(c *ldap.Conn) error) error {
// TODO(ericchiang): support context here
var (
conn *ldap.Conn
err error
)
switch {
case c.InsecureNoSSL:
conn, err = ldap.Dial("tcp", c.Host)
case c.StartTLS:
conn, err = ldap.Dial("tcp", c.Host)
if err != nil {
return fmt.Errorf("failed to connect: %v", err)
}
if err := conn.StartTLS(c.tlsConfig); err != nil {
return fmt.Errorf("start TLS failed: %v", err)
}
default:
conn, err = ldap.DialTLS("tcp", c.Host, c.tlsConfig)
}
if err != nil {
return fmt.Errorf("failed to connect: %v", err)
}
defer conn.Close()
// If bindDN and bindPW are empty this will default to an anonymous bind.
if c.BindDN == "" && c.BindPW == "" {
if err := conn.UnauthenticatedBind(""); err != nil {
return fmt.Errorf("ldap: initial anonymous bind failed: %v", err)
}
} else if err := conn.Bind(c.BindDN, c.BindPW); err != nil {
return fmt.Errorf("ldap: initial bind for user %q failed: %v", c.BindDN, err)
}
return f(conn)
}
func getAttrs(e ldap.Entry, name string) []string {
for _, a := range e.Attributes {
if a.Name != name {
continue
}
return a.Values
}
if name == "DN" {
return []string{e.DN}
}
return nil
}
func getAttr(e ldap.Entry, name string) string {
if a := getAttrs(e, name); len(a) > 0 {
return a[0]
}
return ""
}
func (c *ldapConnector) identityFromEntry(user ldap.Entry) (ident connector.Identity, err error) {
// If we're missing any attributes, such as email or ID, we want to report
// an error rather than continuing.
missing := []string{}
// Fill the identity struct using the attributes from the user entry.
if ident.UserID = getAttr(user, c.UserSearch.IDAttr); ident.UserID == "" {
missing = append(missing, c.UserSearch.IDAttr)
}
if c.UserSearch.NameAttr != "" {
if ident.Username = getAttr(user, c.UserSearch.NameAttr); ident.Username == "" {
missing = append(missing, c.UserSearch.NameAttr)
}
}
if c.UserSearch.PreferredUsernameAttrAttr != "" {
if ident.PreferredUsername = getAttr(user, c.UserSearch.PreferredUsernameAttrAttr); ident.PreferredUsername == "" {
missing = append(missing, c.UserSearch.PreferredUsernameAttrAttr)
}
}
if c.UserSearch.EmailSuffix != "" {
ident.Email = ident.Username + "@" + c.UserSearch.EmailSuffix
} else if ident.Email = getAttr(user, c.UserSearch.EmailAttr); ident.Email == "" {
missing = append(missing, c.UserSearch.EmailAttr)
}
// TODO(ericchiang): Let this value be set from an attribute.
ident.EmailVerified = true
if len(missing) != 0 {
err := fmt.Errorf("ldap: entry %q missing following required attribute(s): %q", user.DN, missing)
return connector.Identity{}, err
}
return ident, nil
}
func (c *ldapConnector) userEntry(conn *ldap.Conn, username string) (user ldap.Entry, found bool, err error) {
filter := fmt.Sprintf("(%s=%s)", c.UserSearch.Username, ldap.EscapeFilter(username))
if c.UserSearch.Filter != "" {
filter = fmt.Sprintf("(&%s%s)", c.UserSearch.Filter, filter)
}
// Initial search.
req := &ldap.SearchRequest{
BaseDN: c.UserSearch.BaseDN,
Filter: filter,
Scope: c.userSearchScope,
// We only need to search for these specific requests.
Attributes: []string{
c.UserSearch.IDAttr,
c.UserSearch.EmailAttr,
// TODO(ericchiang): what if this contains duplicate values?
},
}
for _, matcher := range c.userMatchers() {
req.Attributes = append(req.Attributes, matcher.UserAttr)
}
if c.UserSearch.NameAttr != "" {
req.Attributes = append(req.Attributes, c.UserSearch.NameAttr)
}
if c.UserSearch.PreferredUsernameAttrAttr != "" {
req.Attributes = append(req.Attributes, c.UserSearch.PreferredUsernameAttrAttr)
}
c.logger.Infof("performing ldap search %s %s %s",
req.BaseDN, scopeString(req.Scope), req.Filter)
resp, err := conn.Search(req)
if err != nil {
return ldap.Entry{}, false, fmt.Errorf("ldap: search with filter %q failed: %v", req.Filter, err)
}
switch n := len(resp.Entries); n {
case 0:
c.logger.Errorf("ldap: no results returned for filter: %q", filter)
return ldap.Entry{}, false, nil
case 1:
user = *resp.Entries[0]
c.logger.Infof("username %q mapped to entry %s", username, user.DN)
return user, true, nil
default:
return ldap.Entry{}, false, fmt.Errorf("ldap: filter returned multiple (%d) results: %q", n, filter)
}
}
func (c *ldapConnector) Login(ctx context.Context, s connector.Scopes, username, password string) (ident connector.Identity, validPass bool, err error) {
// make this check to avoid unauthenticated bind to the LDAP server.
if password == "" {
return connector.Identity{}, false, nil
}
var (
// We want to return a different error if the user's password is incorrect vs
// if there was an error.
incorrectPass = false
user ldap.Entry
)
err = c.do(ctx, func(conn *ldap.Conn) error {
entry, found, err := c.userEntry(conn, username)
if err != nil {
return err
}
if !found {
incorrectPass = true
return nil
}
user = entry
// Try to authenticate as the distinguished name.
if err := conn.Bind(user.DN, password); err != nil {
// Detect a bad password through the LDAP error code.
if ldapErr, ok := err.(*ldap.Error); ok {
switch ldapErr.ResultCode {
case ldap.LDAPResultInvalidCredentials:
c.logger.Errorf("ldap: invalid password for user %q", user.DN)
incorrectPass = true
return nil
case ldap.LDAPResultConstraintViolation:
c.logger.Errorf("ldap: constraint violation for user %q: %s", user.DN, ldapErr.Error())
incorrectPass = true
return nil
}
} // will also catch all ldap.Error without a case statement above
return fmt.Errorf("ldap: failed to bind as dn %q: %v", user.DN, err)
}
return nil
})
if err != nil {
return connector.Identity{}, false, err
}
if incorrectPass {
return connector.Identity{}, false, nil
}
if ident, err = c.identityFromEntry(user); err != nil {
return connector.Identity{}, false, err
}
if s.Groups {
groups, err := c.groups(ctx, user)
if err != nil {
return connector.Identity{}, false, fmt.Errorf("ldap: failed to query groups: %v", err)
}
ident.Groups = groups
}
if s.OfflineAccess {
refresh := refreshData{
Username: username,
Entry: user,
}
// Encode entry for follow up requests such as the groups query and
// refresh attempts.
if ident.ConnectorData, err = json.Marshal(refresh); err != nil {
return connector.Identity{}, false, fmt.Errorf("ldap: marshal entry: %v", err)
}
}
return ident, true, nil
}
func (c *ldapConnector) Refresh(ctx context.Context, s connector.Scopes, ident connector.Identity) (connector.Identity, error) {
var data refreshData
if err := json.Unmarshal(ident.ConnectorData, &data); err != nil {
return ident, fmt.Errorf("ldap: failed to unmarshal internal data: %v", err)
}
var user ldap.Entry
err := c.do(ctx, func(conn *ldap.Conn) error {
entry, found, err := c.userEntry(conn, data.Username)
if err != nil {
return err
}
if !found {
return fmt.Errorf("ldap: user not found %q", data.Username)
}
user = entry
return nil
})
if err != nil {
return ident, err
}
if user.DN != data.Entry.DN {
return ident, fmt.Errorf("ldap: refresh for username %q expected DN %q got %q", data.Username, data.Entry.DN, user.DN)
}
newIdent, err := c.identityFromEntry(user)
if err != nil {
return ident, err
}
newIdent.ConnectorData = ident.ConnectorData
if s.Groups {
groups, err := c.groups(ctx, user)
if err != nil {
return connector.Identity{}, fmt.Errorf("ldap: failed to query groups: %v", err)
}
newIdent.Groups = groups
}
return newIdent, nil
}
func (c *ldapConnector) groups(ctx context.Context, user ldap.Entry) ([]string, error) {
if c.GroupSearch.BaseDN == "" {
c.logger.Debugf("No groups returned for %q because no groups baseDN has been configured.", getAttr(user, c.UserSearch.NameAttr))
return nil, nil
}
var groups []*ldap.Entry
for _, matcher := range c.userMatchers() {
for _, attr := range getAttrs(user, matcher.UserAttr) {
filter := fmt.Sprintf("(%s=%s)", matcher.GroupAttr, ldap.EscapeFilter(attr))
if c.GroupSearch.Filter != "" {
filter = fmt.Sprintf("(&%s%s)", c.GroupSearch.Filter, filter)
}
req := &ldap.SearchRequest{
BaseDN: c.GroupSearch.BaseDN,
Filter: filter,
Scope: c.groupSearchScope,
Attributes: []string{c.GroupSearch.NameAttr},
}
gotGroups := false
if err := c.do(ctx, func(conn *ldap.Conn) error {
c.logger.Infof("performing ldap search %s %s %s",
req.BaseDN, scopeString(req.Scope), req.Filter)
resp, err := conn.Search(req)
if err != nil {
return fmt.Errorf("ldap: search failed: %v", err)
}
gotGroups = len(resp.Entries) != 0
groups = append(groups, resp.Entries...)
return nil
}); err != nil {
return nil, err
}
if !gotGroups {
// TODO(ericchiang): Is this going to spam the logs?
c.logger.Errorf("ldap: groups search with filter %q returned no groups", filter)
}
}
}
groupNames := make([]string, 0, len(groups))
for _, group := range groups {
name := getAttr(*group, c.GroupSearch.NameAttr)
if name == "" {
// Be obnoxious about missing missing attributes. If the group entry is
// missing its name attribute, that indicates a misconfiguration.
//
// In the future we can add configuration options to just log these errors.
return nil, fmt.Errorf("ldap: group entity %q missing required attribute %q",
group.DN, c.GroupSearch.NameAttr)
}
groupNames = append(groupNames, name)
}
return groupNames, nil
}
func (c *ldapConnector) Prompt() string {
return c.UsernamePrompt
}