Case insensitive behavior for LDAP (#4238)

CHANGELOG.md

@@ -15,6 +15,11 @@ DEPRECATIONS/CHANGES:
    accommodate this as best as possible, and users of other tools may have to
    make adjustments, but in the end we felt that the ends did not justify the
    means and we needed to prioritize security over operational convenience.
+ * LDAP auth method case sensitivity: We now treat usernames and groups
+   configured locally for policy assignment in a case insensitive fashion by
+   default. Existing configurations will continue to work as they do now;
+   however, the next time a configuration is written `case_sensitive_names`
+   will need to be explicitly set to `true`.
 
 FEATURES:
 

builtin/credential/ldap/backend.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"math"
+	"strings"
 	"text/template"
 
 	"github.com/go-ldap/ldap"
@@ -173,8 +174,13 @@ func (b *backend) Login(ctx context.Context, req *logical.Request, username stri
 	}
 
 	var allGroups []string
+	canonicalUsername := username
+	cs := *cfg.CaseSensitiveNames
+	if !cs {
+		canonicalUsername = strings.ToLower(username)
+	}
 	// Import the custom added groups from ldap backend
-	user, err := b.User(ctx, req.Storage, username)
+	user, err := b.User(ctx, req.Storage, canonicalUsername)
 	if err == nil && user != nil && user.Groups != nil {
 		if b.Logger().IsDebug() {
 			b.Logger().Debug("adding local groups", "num_local_groups", len(user.Groups), "local_groups", user.Groups)
@@ -184,9 +190,18 @@ func (b *backend) Login(ctx context.Context, req *logical.Request, username stri
 	// Merge local and LDAP groups
 	allGroups = append(allGroups, ldapGroups...)
 
+	canonicalGroups := allGroups
+	// If not case sensitive, lowercase all
+	if !cs {
+		canonicalGroups = make([]string, len(allGroups))
+		for i, v := range allGroups {
+			canonicalGroups[i] = strings.ToLower(v)
+		}
+	}
+
 	// Retrieve policies
 	var policies []string
-	for _, groupName := range allGroups {
+	for _, groupName := range canonicalGroups {
 		group, err := b.Group(ctx, req.Storage, groupName)
 		if err == nil && group != nil {
 			policies = append(policies, group.Policies...)

builtin/credential/ldap/backend_test.go

@@ -31,6 +31,182 @@ func createBackendWithStorage(t *testing.T) (*backend, logical.Storage) {
 	return b, config.StorageView
 }
 
+func TestLdapAuthBackend_CaseSensitivity(t *testing.T) {
+	var resp *logical.Response
+	var err error
+	b, storage := createBackendWithStorage(t)
+
+	ctx := context.Background()
+
+	testVals := func(caseSensitive bool) {
+		// Clear storage
+		userList, err := storage.List(ctx, "user/")
+		if err != nil {
+			t.Fatal(err)
+		}
+		for _, user := range userList {
+			err = storage.Delete(ctx, "user/"+user)
+			if err != nil {
+				t.Fatal(err)
+			}
+		}
+		groupList, err := storage.List(ctx, "group/")
+		if err != nil {
+			t.Fatal(err)
+		}
+		for _, group := range groupList {
+			err = storage.Delete(ctx, "group/"+group)
+			if err != nil {
+				t.Fatal(err)
+			}
+		}
+
+		configReq := &logical.Request{
+			Path:      "config",
+			Operation: logical.ReadOperation,
+			Storage:   storage,
+		}
+		resp, err = b.HandleRequest(ctx, configReq)
+		if err != nil || (resp != nil && resp.IsError()) {
+			t.Fatalf("err:%v resp:%#v", err, resp)
+		}
+		if resp == nil {
+			t.Fatal("nil response")
+		}
+		if resp.Data["case_sensitive_names"].(bool) != caseSensitive {
+			t.Fatalf("expected case sensitivity %t, got %t", caseSensitive, resp.Data["case_sensitive_names"].(bool))
+		}
+
+		groupReq := &logical.Request{
+			Operation: logical.UpdateOperation,
+			Data: map[string]interface{}{
+				"policies": "grouppolicy",
+			},
+			Path:    "groups/EngineerS",
+			Storage: storage,
+		}
+		resp, err = b.HandleRequest(ctx, groupReq)
+		if err != nil || (resp != nil && resp.IsError()) {
+			t.Fatalf("err:%v resp:%#v", err, resp)
+		}
+		keys, err := storage.List(ctx, "group/")
+		if err != nil {
+			t.Fatal(err)
+		}
+		switch caseSensitive {
+		case true:
+			if keys[0] != "EngineerS" {
+				t.Fatalf("bad: %s", keys[0])
+			}
+		default:
+			if keys[0] != "engineers" {
+				t.Fatalf("bad: %s", keys[0])
+			}
+		}
+
+		userReq := &logical.Request{
+			Operation: logical.UpdateOperation,
+			Data: map[string]interface{}{
+				"groups":   "EngineerS",
+				"policies": "userpolicy",
+			},
+			Path:    "users/teSlA",
+			Storage: storage,
+		}
+		resp, err = b.HandleRequest(ctx, userReq)
+		if err != nil || (resp != nil && resp.IsError()) {
+			t.Fatalf("err:%v resp:%#v", err, resp)
+		}
+		keys, err = storage.List(ctx, "user/")
+		if err != nil {
+			t.Fatal(err)
+		}
+		switch caseSensitive {
+		case true:
+			if keys[0] != "teSlA" {
+				t.Fatalf("bad: %s", keys[0])
+			}
+		default:
+			if keys[0] != "tesla" {
+				t.Fatalf("bad: %s", keys[0])
+			}
+		}
+
+		if caseSensitive {
+			// The online test server is actually case sensitive so we need to
+			// write again so it works
+			userReq = &logical.Request{
+				Operation: logical.UpdateOperation,
+				Data: map[string]interface{}{
+					"groups":   "EngineerS",
+					"policies": "userpolicy",
+				},
+				Path:    "users/tesla",
+				Storage: storage,
+			}
+			resp, err = b.HandleRequest(ctx, userReq)
+			if err != nil || (resp != nil && resp.IsError()) {
+				t.Fatalf("err:%v resp:%#v", err, resp)
+			}
+		}
+
+		loginReq := &logical.Request{
+			Operation: logical.UpdateOperation,
+			Path:      "login/tesla",
+			Data: map[string]interface{}{
+				"password": "password",
+			},
+			Storage: storage,
+		}
+		resp, err = b.HandleRequest(ctx, loginReq)
+		if err != nil || (resp != nil && resp.IsError()) {
+			t.Fatalf("err:%v resp:%#v", err, resp)
+		}
+		expected := []string{"grouppolicy", "userpolicy"}
+		if !reflect.DeepEqual(expected, resp.Auth.Policies) {
+			t.Fatalf("bad: policies: expected: %q, actual: %q", expected, resp.Auth.Policies)
+		}
+	}
+
+	configReq := &logical.Request{
+		Operation: logical.UpdateOperation,
+		Path:      "config",
+		Data: map[string]interface{}{
+			// Online LDAP test server
+			// http://www.forumsys.com/tutorials/integration-how-to/ldap/online-ldap-test-server/
+			"url":      "ldap://ldap.forumsys.com",
+			"userattr": "uid",
+			"userdn":   "dc=example,dc=com",
+			"groupdn":  "dc=example,dc=com",
+			"binddn":   "cn=read-only-admin,dc=example,dc=com",
+		},
+		Storage: storage,
+	}
+	resp, err = b.HandleRequest(ctx, configReq)
+	if err != nil || (resp != nil && resp.IsError()) {
+		t.Fatalf("err:%v resp:%#v", err, resp)
+	}
+
+	testVals(false)
+
+	// Check that if the value is nil, on read it is case sensitive
+	configEntry, err := b.Config(ctx, configReq)
+	if err != nil {
+		t.Fatal(err)
+	}
+	configEntry.CaseSensitiveNames = nil
+	entry, err := logical.StorageEntryJSON("config", configEntry)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = configReq.Storage.Put(ctx, entry)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testVals(true)
+}
+
 func TestLdapAuthBackend_UserPolicies(t *testing.T) {
 	var resp *logical.Response
 	var err error
@@ -278,10 +454,11 @@ func testAccStepConfigUrl(t *testing.T) logicaltest.TestStep {
 		Data: map[string]interface{}{
 			// Online LDAP test server
 			// http://www.forumsys.com/tutorials/integration-how-to/ldap/online-ldap-test-server/
-			"url":      "ldap://ldap.forumsys.com",
+			"url":                  "ldap://ldap.forumsys.com",
-			"userattr": "uid",
+			"userattr":             "uid",
-			"userdn":   "dc=example,dc=com",
+			"userdn":               "dc=example,dc=com",
-			"groupdn":  "dc=example,dc=com",
+			"groupdn":              "dc=example,dc=com",
+			"case_sensitive_names": true,
 		},
 	}
 }
@@ -294,12 +471,13 @@ func testAccStepConfigUrlWithAuthBind(t *testing.T) logicaltest.TestStep {
 			// Online LDAP test server
 			// http://www.forumsys.com/tutorials/integration-how-to/ldap/online-ldap-test-server/
 			// In this test we also exercise multiple URL support
-			"url":      "foobar://ldap.example.com,ldap://ldap.forumsys.com",
+			"url":                  "foobar://ldap.example.com,ldap://ldap.forumsys.com",
-			"userattr": "uid",
+			"userattr":             "uid",
-			"userdn":   "dc=example,dc=com",
+			"userdn":               "dc=example,dc=com",
-			"groupdn":  "dc=example,dc=com",
+			"groupdn":              "dc=example,dc=com",
-			"binddn":   "cn=read-only-admin,dc=example,dc=com",
+			"binddn":               "cn=read-only-admin,dc=example,dc=com",
-			"bindpass": "password",
+			"bindpass":             "password",
+			"case_sensitive_names": true,
 		},
 	}
 }
@@ -311,11 +489,12 @@ func testAccStepConfigUrlWithDiscover(t *testing.T) logicaltest.TestStep {
 		Data: map[string]interface{}{
 			// Online LDAP test server
 			// http://www.forumsys.com/tutorials/integration-how-to/ldap/online-ldap-test-server/
-			"url":        "ldap://ldap.forumsys.com",
+			"url":                  "ldap://ldap.forumsys.com",
-			"userattr":   "uid",
+			"userattr":             "uid",
-			"userdn":     "dc=example,dc=com",
+			"userdn":               "dc=example,dc=com",
-			"groupdn":    "dc=example,dc=com",
+			"groupdn":              "dc=example,dc=com",
-			"discoverdn": true,
+			"discoverdn":           true,
+			"case_sensitive_names": true,
 		},
 	}
 }
@@ -327,10 +506,11 @@ func testAccStepConfigUrlNoGroupDN(t *testing.T) logicaltest.TestStep {
 		Data: map[string]interface{}{
 			// Online LDAP test server
 			// http://www.forumsys.com/tutorials/integration-how-to/ldap/online-ldap-test-server/
-			"url":        "ldap://ldap.forumsys.com",
+			"url":                  "ldap://ldap.forumsys.com",
-			"userattr":   "uid",
+			"userattr":             "uid",
-			"userdn":     "dc=example,dc=com",
+			"userdn":               "dc=example,dc=com",
-			"discoverdn": true,
+			"discoverdn":           true,
+			"case_sensitive_names": true,
 		},
 	}
 }

builtin/credential/ldap/path_config.go

@@ -14,6 +14,7 @@ import (
 	"github.com/go-ldap/ldap"
 	log "github.com/hashicorp/go-hclog"
 	multierror "github.com/hashicorp/go-multierror"
+	"github.com/hashicorp/vault/helper/consts"
 	"github.com/hashicorp/vault/helper/tlsutil"
 	"github.com/hashicorp/vault/logical"
 	"github.com/hashicorp/vault/logical/framework"
@@ -109,11 +110,17 @@ Default: cn`,
 				Default:     "tls12",
 				Description: "Maximum TLS version to use. Accepted values are 'tls10', 'tls11' or 'tls12'. Defaults to 'tls12'",
 			},
+
 			"deny_null_bind": &framework.FieldSchema{
 				Type:        framework.TypeBool,
 				Default:     true,
 				Description: "Denies an unauthenticated LDAP bind request if the user's password is empty; defaults to true",
 			},
+
+			"case_sensitive_names": &framework.FieldSchema{
+				Type:        framework.TypeBool,
+				Description: "If true, case sensitivity will be used when comparing usernames and groups for matching policies.",
+			},
 		},
 
 		Callbacks: map[logical.Operation]framework.OperationFunc{
@@ -149,6 +156,9 @@ func (b *backend) Config(ctx context.Context, req *logical.Request) (*ConfigEntr
 
 	if storedConfig == nil {
 		// No user overrides, return default configuration
+		result.CaseSensitiveNames = new(bool)
+		*result.CaseSensitiveNames = false
+
 		return result, nil
 	}
 
@@ -158,6 +168,24 @@ func (b *backend) Config(ctx context.Context, req *logical.Request) (*ConfigEntr
 		return nil, err
 	}
 
+	var persistNeeded bool
+	if result.CaseSensitiveNames == nil {
+		// Upgrade from before switching to case-insensitive
+		result.CaseSensitiveNames = new(bool)
+		*result.CaseSensitiveNames = true
+		persistNeeded = true
+	}
+
+	if persistNeeded && (b.System().LocalMount() || !b.System().ReplicationState().HasState(consts.ReplicationPerformanceSecondary)) {
+		entry, err := logical.StorageEntryJSON("config", result)
+		if err != nil {
+			return nil, err
+		}
+		if err := req.Storage.Put(ctx, entry); err != nil {
+			return nil, err
+		}
+	}
+
 	result.logger = b.Logger()
 
 	return result, nil
@@ -174,21 +202,22 @@ func (b *backend) pathConfigRead(ctx context.Context, req *logical.Request, d *f
 
 	resp := &logical.Response{
 		Data: map[string]interface{}{
-			"url":             cfg.Url,
+			"url":                  cfg.Url,
-			"userdn":          cfg.UserDN,
+			"userdn":               cfg.UserDN,
-			"groupdn":         cfg.GroupDN,
+			"groupdn":              cfg.GroupDN,
-			"groupfilter":     cfg.GroupFilter,
+			"groupfilter":          cfg.GroupFilter,
-			"groupattr":       cfg.GroupAttr,
+			"groupattr":            cfg.GroupAttr,
-			"upndomain":       cfg.UPNDomain,
+			"upndomain":            cfg.UPNDomain,
-			"userattr":        cfg.UserAttr,
+			"userattr":             cfg.UserAttr,
-			"certificate":     cfg.Certificate,
+			"certificate":          cfg.Certificate,
-			"insecure_tls":    cfg.InsecureTLS,
+			"insecure_tls":         cfg.InsecureTLS,
-			"starttls":        cfg.StartTLS,
+			"starttls":             cfg.StartTLS,
-			"binddn":          cfg.BindDN,
+			"binddn":               cfg.BindDN,
-			"deny_null_bind":  cfg.DenyNullBind,
+			"deny_null_bind":       cfg.DenyNullBind,
-			"discoverdn":      cfg.DiscoverDN,
+			"discoverdn":           cfg.DiscoverDN,
-			"tls_min_version": cfg.TLSMinVersion,
+			"tls_min_version":      cfg.TLSMinVersion,
-			"tls_max_version": cfg.TLSMaxVersion,
+			"tls_max_version":      cfg.TLSMaxVersion,
+			"case_sensitive_names": *cfg.CaseSensitiveNames,
 		},
 	}
 	return resp, nil
@@ -282,23 +311,33 @@ func (b *backend) newConfigEntry(d *framework.FieldData) (*ConfigEntry, error) {
 	if startTLS {
 		cfg.StartTLS = startTLS
 	}
+
 	bindDN := d.Get("binddn").(string)
 	if bindDN != "" {
 		cfg.BindDN = bindDN
 	}
+
 	bindPass := d.Get("bindpass").(string)
 	if bindPass != "" {
 		cfg.BindPassword = bindPass
 	}
+
 	denyNullBind := d.Get("deny_null_bind").(bool)
 	if denyNullBind {
 		cfg.DenyNullBind = denyNullBind
 	}
+
 	discoverDN := d.Get("discoverdn").(bool)
 	if discoverDN {
 		cfg.DiscoverDN = discoverDN
 	}
 
+	caseSensitiveNames, ok := d.GetOk("case_sensitive_names")
+	if ok {
+		cfg.CaseSensitiveNames = new(bool)
+		*cfg.CaseSensitiveNames = caseSensitiveNames.(bool)
+	}
+
 	return cfg, nil
 }
 
@@ -309,6 +348,13 @@ func (b *backend) pathConfigWrite(ctx context.Context, req *logical.Request, d *
 		return logical.ErrorResponse(err.Error()), nil
 	}
 
+	// On write, if not specified, use false. We do this here so upgrade logic
+	// works since it calls the same newConfigEntry function
+	if cfg.CaseSensitiveNames == nil {
+		cfg.CaseSensitiveNames = new(bool)
+		*cfg.CaseSensitiveNames = false
+	}
+
 	entry, err := logical.StorageEntryJSON("config", cfg)
 	if err != nil {
 		return nil, err
@@ -321,23 +367,24 @@ func (b *backend) pathConfigWrite(ctx context.Context, req *logical.Request, d *
 }
 
 type ConfigEntry struct {
-	logger        log.Logger
+	logger             log.Logger
-	Url           string `json:"url" structs:"url" mapstructure:"url"`
+	Url                string `json:"url"`
-	UserDN        string `json:"userdn" structs:"userdn" mapstructure:"userdn"`
+	UserDN             string `json:"userdn"`
-	GroupDN       string `json:"groupdn" structs:"groupdn" mapstructure:"groupdn"`
+	GroupDN            string `json:"groupdn"`
-	GroupFilter   string `json:"groupfilter" structs:"groupfilter" mapstructure:"groupfilter"`
+	GroupFilter        string `json:"groupfilter"`
-	GroupAttr     string `json:"groupattr" structs:"groupattr" mapstructure:"groupattr"`
+	GroupAttr          string `json:"groupattr"`
-	UPNDomain     string `json:"upndomain" structs:"upndomain" mapstructure:"upndomain"`
+	UPNDomain          string `json:"upndomain"`
-	UserAttr      string `json:"userattr" structs:"userattr" mapstructure:"userattr"`
+	UserAttr           string `json:"userattr"`
-	Certificate   string `json:"certificate" structs:"certificate" mapstructure:"certificate"`
+	Certificate        string `json:"certificate"`
-	InsecureTLS   bool   `json:"insecure_tls" structs:"insecure_tls" mapstructure:"insecure_tls"`
+	InsecureTLS        bool   `json:"insecure_tls"`
-	StartTLS      bool   `json:"starttls" structs:"starttls" mapstructure:"starttls"`
+	StartTLS           bool   `json:"starttls"`
-	BindDN        string `json:"binddn" structs:"binddn" mapstructure:"binddn"`
+	BindDN             string `json:"binddn"`
-	BindPassword  string `json:"bindpass" structs:"bindpass" mapstructure:"bindpass"`
+	BindPassword       string `json:"bindpass"`
-	DenyNullBind  bool   `json:"deny_null_bind" structs:"deny_null_bind" mapstructure:"deny_null_bind"`
+	DenyNullBind       bool   `json:"deny_null_bind"`
-	DiscoverDN    bool   `json:"discoverdn" structs:"discoverdn" mapstructure:"discoverdn"`
+	DiscoverDN         bool   `json:"discoverdn"`
-	TLSMinVersion string `json:"tls_min_version" structs:"tls_min_version" mapstructure:"tls_min_version"`
+	TLSMinVersion      string `json:"tls_min_version"`
-	TLSMaxVersion string `json:"tls_max_version" structs:"tls_max_version" mapstructure:"tls_max_version"`
+	TLSMaxVersion      string `json:"tls_max_version"`
+	CaseSensitiveNames *bool  `json:"case_sensitive_names,omitempty`
 }
 
 func (c *ConfigEntry) GetTLSConfig(host string) (*tls.Config, error) {

builtin/credential/ldap/path_groups.go

@@ -2,6 +2,7 @@ package ldap
 
 import (
 	"context"
+	"strings"
 
 	"github.com/hashicorp/vault/helper/policyutil"
 	"github.com/hashicorp/vault/logical"
@@ -74,7 +75,20 @@ func (b *backend) pathGroupDelete(ctx context.Context, req *logical.Request, d *
 }
 
 func (b *backend) pathGroupRead(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
-	group, err := b.Group(ctx, req.Storage, d.Get("name").(string))
+	groupname := d.Get("name").(string)
+
+	cfg, err := b.Config(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	if cfg == nil {
+		return logical.ErrorResponse("ldap backend not configured"), nil
+	}
+	if !*cfg.CaseSensitiveNames {
+		groupname = strings.ToLower(groupname)
+	}
+
+	group, err := b.Group(ctx, req.Storage, groupname)
 	if err != nil {
 		return nil, err
 	}
@@ -90,8 +104,21 @@ func (b *backend) pathGroupRead(ctx context.Context, req *logical.Request, d *fr
 }
 
 func (b *backend) pathGroupWrite(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
+	groupname := d.Get("name").(string)
+
+	cfg, err := b.Config(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	if cfg == nil {
+		return logical.ErrorResponse("ldap backend not configured"), nil
+	}
+	if !*cfg.CaseSensitiveNames {
+		groupname = strings.ToLower(groupname)
+	}
+
 	// Store it
-	entry, err := logical.StorageEntryJSON("group/"+d.Get("name").(string), &GroupEntry{
+	entry, err := logical.StorageEntryJSON("group/"+groupname, &GroupEntry{
 		Policies: policyutil.ParsePolicies(d.Get("policies")),
 	})
 	if err != nil {

builtin/credential/ldap/path_users.go

@@ -81,7 +81,20 @@ func (b *backend) pathUserDelete(ctx context.Context, req *logical.Request, d *f
 }
 
 func (b *backend) pathUserRead(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
-	user, err := b.User(ctx, req.Storage, d.Get("name").(string))
+	username := d.Get("name").(string)
+
+	cfg, err := b.Config(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	if cfg == nil {
+		return logical.ErrorResponse("ldap backend not configured"), nil
+	}
+	if !*cfg.CaseSensitiveNames {
+		username = strings.ToLower(username)
+	}
+
+	user, err := b.User(ctx, req.Storage, username)
 	if err != nil {
 		return nil, err
 	}
@@ -98,15 +111,29 @@ func (b *backend) pathUserRead(ctx context.Context, req *logical.Request, d *fra
 }
 
 func (b *backend) pathUserWrite(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
-	name := d.Get("name").(string)
+	lowercaseGroups := false
-	groups := strutil.RemoveDuplicates(strutil.ParseStringSlice(d.Get("groups").(string), ","), false)
+	username := d.Get("name").(string)
+
+	cfg, err := b.Config(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	if cfg == nil {
+		return logical.ErrorResponse("ldap backend not configured"), nil
+	}
+	if !*cfg.CaseSensitiveNames {
+		username = strings.ToLower(username)
+		lowercaseGroups = true
+	}
+
+	groups := strutil.RemoveDuplicates(strutil.ParseStringSlice(d.Get("groups").(string), ","), lowercaseGroups)
 	policies := policyutil.ParsePolicies(d.Get("policies"))
 	for i, g := range groups {
 		groups[i] = strings.TrimSpace(g)
 	}
 
 	// Store it
-	entry, err := logical.StorageEntryJSON("user/"+name, &UserEntry{
+	entry, err := logical.StorageEntryJSON("user/"+username, &UserEntry{
 		Groups:   groups,
 		Policies: policies,
 	})

website/source/api/auth/ldap/index.html.md

@@ -28,6 +28,11 @@ This endpoint configures the LDAP auth method.
 
 - `url` `(string: <required>)` – The LDAP server to connect to. Examples:
   `ldap://ldap.myorg.com`, `ldaps://ldap.myorg.com:636`
+- `case_sensitive_names` `(bool: false)` – If set, user and group names
+  assigned to policies within the backend will be case sensitive. Otherwise,
+  names will be normalized to lower case. Case will still be preserved when
+  sending the username to the LDAP server at login time; this is only for
+  matching local user/group definitions.
 - `starttls` `(bool: false)` – If true, issues a `StartTLS` command after
   establishing an unencrypted connection.
 - `tls_min_version` `(string: tls12)` – Minimum TLS version to use. Accepted