hydra-werther/internal/ldapclient/ldapclient.go

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/*
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Copyright (c) JSC iCore.
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This source code is licensed under the MIT license found in the
LICENSE file in the root directory of this source tree.
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*/
package ldapclient
import (
"context"
"encoding/json"
"fmt"
"net"
"strings"
"sync"
"time"
"github.com/coocood/freecache"
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"github.com/i-core/rlog"
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"github.com/pkg/errors"
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"go.uber.org/zap"
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ldap "gopkg.in/ldap.v2"
)
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var (
// errInvalidCredentials is an error that happens when a user's password is invalid.
errInvalidCredentials = fmt.Errorf("invalid credentials")
// errConnectionTimeout is an error that happens when no one LDAP endpoint responds.
errConnectionTimeout = fmt.Errorf("connection timeout")
// errMissedUsername is an error that happens
errMissedUsername = errors.New("username is missed")
// errUnknownUsername is an error that happens
errUnknownUsername = errors.New("unknown username")
)
type conn interface {
Bind(bindDN, password string) error
SearchUser(user string, attrs ...string) ([]map[string]interface{}, error)
SearchUserRoles(user string, attrs ...string) ([]map[string]interface{}, error)
Close()
}
type connector interface {
Connect(ctx context.Context, addr string) (conn, error)
}
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// Config is a LDAP configuration.
type Config struct {
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Endpoints []string `envconfig:"endpoints" required:"true" desc:"a LDAP's server URLs as \"<address>:<port>\""`
BindDN string `envconfig:"binddn" desc:"a LDAP bind DN"`
BindPass string `envconfig:"bindpw" json:"-" desc:"a LDAP bind password"`
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BaseDN string `envconfig:"basedn" required:"true" desc:"a LDAP base DN for searching users"`
AttrClaims map[string]string `envconfig:"attr_claims" default:"name:name,sn:family_name,givenName:given_name,mail:email" desc:"a mapping of LDAP attributes to OpenID connect claims"`
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RoleBaseDN string `envconfig:"role_basedn" required:"true" desc:"a LDAP base DN for searching roles"`
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RoleAttr string `envconfig:"role_attr" default:"description" desc:"a LDAP group's attribute that contains a role's name"`
RoleClaim string `envconfig:"role_claim" default:"https://github.com/i-core/werther/claims/roles" desc:"a name of an OpenID Connect claim that contains user roles"`
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CacheSize int `envconfig:"cache_size" default:"512" desc:"a user info cache's size in KiB"`
CacheTTL time.Duration `envconfig:"cache_ttl" default:"30m" desc:"a user info cache TTL"`
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}
// Client is a LDAP client (compatible with Active Directory).
type Client struct {
Config
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connector connector
cache *freecache.Cache
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}
// New creates a new LDAP client.
func New(cnf Config) *Client {
return &Client{
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Config: cnf,
connector: &ldapConnector{BaseDN: cnf.BaseDN, RoleBaseDN: cnf.RoleBaseDN},
cache: freecache.NewCache(cnf.CacheSize * 1024),
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}
}
// Authenticate authenticates a user with a username and password.
// If no username or password in LDAP it returns false and no error.
func (cli *Client) Authenticate(ctx context.Context, username, password string) (bool, error) {
if username == "" || password == "" {
return false, nil
}
var cancel context.CancelFunc
ctx, cancel = context.WithCancel(ctx)
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cn, ok := <-cli.connect(ctx)
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cancel()
if !ok {
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return false, errConnectionTimeout
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}
defer cn.Close()
// Find a user DN by his or her username.
details, err := cli.findBasicUserDetails(cn, username, []string{"dn"})
if err != nil {
return false, err
}
if details == nil {
return false, nil
}
if err := cn.Bind(details["dn"].(string), password); err != nil {
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if err == errInvalidCredentials {
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return false, nil
}
return false, err
}
// Clear the claims' cache because of possible re-authentication. We don't want stale claims after re-login.
if ok := cli.cache.Del([]byte(username)); ok {
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log := rlog.FromContext(ctx)
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log.Debug("Cleared user's OIDC claims in the cache")
}
return true, nil
}
// FindOIDCClaims finds all OIDC claims for a user.
func (cli *Client) FindOIDCClaims(ctx context.Context, username string) (map[string]interface{}, error) {
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if username == "" {
return nil, errMissedUsername
}
log := rlog.FromContext(ctx).Sugar()
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// Retrieving from LDAP is slow. So, we try to get claims for the given username from the cache.
switch cdata, err := cli.cache.Get([]byte(username)); err {
case nil:
var claims map[string]interface{}
if err = json.Unmarshal(cdata, &claims); err != nil {
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log.Info("Failed to unmarshal user's OIDC claims", zap.Error(err), "data", cdata)
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return nil, err
}
log.Debug("Retrieved user's OIDC claims from the cache", "claims", claims)
return claims, nil
case freecache.ErrNotFound:
log.Debug("User's OIDC claims is not found in the cache")
default:
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log.Infow("Failed to retrieve user's OIDC claims from the cache", zap.Error(err))
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}
// Try to make multiple TCP connections to the LDAP server for getting claims.
// Accept the first one, and cancel others.
var cancel context.CancelFunc
ctx, cancel = context.WithCancel(ctx)
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cn, ok := <-cli.connect(ctx)
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cancel()
if !ok {
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return nil, errConnectionTimeout
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}
defer cn.Close()
// We need to find LDAP attribute's names for all required claims.
attrs := []string{"dn"}
for k := range cli.AttrClaims {
attrs = append(attrs, k)
}
// Find the attributes in the LDAP server.
details, err := cli.findBasicUserDetails(cn, username, attrs)
if err != nil {
return nil, err
}
if details == nil {
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return nil, errUnknownUsername
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}
log.Infow("Retrieved user's info from LDAP", "details", details)
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// Transform the retrieved attributes to corresponding claims.
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claims := make(map[string]interface{})
for attr, v := range details {
if claim, ok := cli.AttrClaims[attr]; ok {
claims[claim] = v
}
}
// User's roles is stored in LDAP as groups. We find all groups in a role's DN
// that include the user as a member.
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entries, err := cn.SearchUserRoles(fmt.Sprintf("%s", details["dn"]), "dn", cli.RoleAttr)
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if err != nil {
return nil, err
}
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roles := make(map[string]interface{})
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for _, entry := range entries {
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roleDN, ok := entry["dn"].(string)
if !ok || roleDN == "" {
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log.Infow("No required LDAP attribute for a role", "ldapAttribute", "dn", "entry", entry)
continue
}
if entry[cli.RoleAttr] == nil {
log.Infow("No required LDAP attribute for a role", "ldapAttribute", cli.RoleAttr, "roleDN", roleDN)
continue
}
// Ensure that a role's DN is inside of the role's base DN.
// It's sufficient to compare the DN's suffix with the base DN.
n, k := len(roleDN), len(cli.RoleBaseDN)
if n < k || !strings.EqualFold(roleDN[n-k:], cli.RoleBaseDN) {
panic("You should never see that")
}
// The DN without the role's base DN must contain a CN and OU
// where the CN is for uniqueness only, and the OU is an application id.
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path := strings.Split(roleDN[:n-k-1], ",")
if len(path) != 2 {
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log.Infow("A role's DN without the role's base DN must contain two nodes only",
"roleBaseDN", cli.RoleBaseDN, "roleDN", roleDN)
continue
}
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appID := path[1][len("OU="):]
var appRoles []interface{}
if v := roles[appID]; v != nil {
appRoles = v.([]interface{})
}
roles[appID] = append(appRoles, entry[cli.RoleAttr])
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}
claims[cli.RoleClaim] = roles
// Save the claims in the cache for future queries.
cdata, err := json.Marshal(claims)
if err != nil {
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log.Infow("Failed to marshal user's OIDC claims for caching", zap.Error(err), "claims", claims)
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}
if err = cli.cache.Set([]byte(username), cdata, int(cli.CacheTTL.Seconds())); err != nil {
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log.Infow("Failed to store user's OIDC claims into the cache", zap.Error(err), "claims", claims)
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}
return claims, nil
}
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func (cli *Client) connect(ctx context.Context) <-chan conn {
var (
wg sync.WaitGroup
ch = make(chan conn)
)
wg.Add(len(cli.Endpoints))
for _, addr := range cli.Endpoints {
go func(addr string) {
defer wg.Done()
log := rlog.FromContext(ctx).Sugar()
cn, err := cli.connector.Connect(ctx, addr)
if err != nil {
log.Debug("Failed to create a LDAP connection", "address", addr)
return
}
select {
case <-ctx.Done():
cn.Close()
log.Debug("a LDAP connection is cancelled", "address", addr)
return
case ch <- cn:
}
}(addr)
}
go func() {
wg.Wait()
close(ch)
}()
return ch
}
// findBasicUserDetails finds user's LDAP attributes that were specified. It returns nil if no such user.
func (cli *Client) findBasicUserDetails(cn conn, username string, attrs []string) (map[string]interface{}, error) {
if cli.BindDN != "" {
// We need to login to a LDAP server with a service account for retrieving user data.
if err := cn.Bind(cli.BindDN, cli.BindPass); err != nil {
return nil, errors.Wrap(err, "failed to login to a LDAP woth a service account")
}
}
entries, err := cn.SearchUser(username, attrs...)
if err != nil {
return nil, err
}
if len(entries) != 1 {
// We didn't find the user.
return nil, nil
}
var (
entry = entries[0]
details = make(map[string]interface{})
)
for _, attr := range attrs {
if v, ok := entry[attr]; ok {
details[attr] = v
}
}
return details, nil
}
type ldapConnector struct {
BaseDN string
RoleBaseDN string
}
func (c *ldapConnector) Connect(ctx context.Context, addr string) (conn, error) {
d := net.Dialer{Timeout: ldap.DefaultTimeout}
tcpcn, err := d.DialContext(ctx, "tcp", addr)
if err != nil {
return nil, err
}
ldapcn := ldap.NewConn(tcpcn, false)
ldapcn.Start()
return &ldapConn{Conn: ldapcn, BaseDN: c.BaseDN, RoleBaseDN: c.RoleBaseDN}, nil
}
type ldapConn struct {
*ldap.Conn
BaseDN string
RoleBaseDN string
}
func (c *ldapConn) Bind(bindDN, password string) error {
err := c.Conn.Bind(bindDN, password)
if ldapErr, ok := err.(*ldap.Error); ok && ldapErr.ResultCode == ldap.LDAPResultInvalidCredentials {
return errInvalidCredentials
}
return err
}
func (c *ldapConn) SearchUser(user string, attrs ...string) ([]map[string]interface{}, error) {
query := fmt.Sprintf(
"(&(|(objectClass=organizationalPerson)(objectClass=inetOrgPerson))"+
"(|(uid=%[1]s)(mail=%[1]s)(userPrincipalName=%[1]s)(sAMAccountName=%[1]s)))", user)
return c.searchEntries(c.BaseDN, query, attrs)
}
func (c *ldapConn) SearchUserRoles(user string, attrs ...string) ([]map[string]interface{}, error) {
query := fmt.Sprintf("(&(objectClass=group)(member=%s))", user)
return c.searchEntries(c.RoleBaseDN, query, attrs)
}
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// searchEntries executes a LDAP query, and returns a result as entries where each entry is mapping of LDAP attributes.
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func (c *ldapConn) searchEntries(baseDN, query string, attrs []string) ([]map[string]interface{}, error) {
req := ldap.NewSearchRequest(baseDN, ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false, query, attrs, nil)
res, err := c.Search(req)
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if err != nil {
return nil, err
}
var entries []map[string]interface{}
for _, v := range res.Entries {
entry := map[string]interface{}{"dn": v.DN}
for _, attr := range v.Attributes {
// We need the first value only for the named attribute.
entry[attr.Name] = attr.Values[0]
}
entries = append(entries, entry)
}
return entries, nil
}