connector/ldap: add multiple user to group mapping

Add an ability to fetch user's membership from
  groups of a different type by specifying multiple
  group attribute to user attribute value matchers
  in the Dex config:

    userMatchers:
    - userAttr: uid
      groupAttr: memberUid
    - userAttr: DN
      groupAttr: member

  In other words the user's groups can be fetched now from
  ldap structure similar to the following:

    dn: cn=john,ou=People,dc=example,dc=org
    objectClass: person
    objectClass: inetOrgPerson
    sn: doe
    cn: john
    uid: johndoe
    mail: johndoe@example.com
    userpassword: bar

    dn: cn=qa,ou=Groups,ou=Portland,dc=example,dc=org
    objectClass: groupOfNames
    cn: qa
    member: cn=john,ou=People,dc=example,dc=org

    dn: cn=logger,ou=UnixGroups,ou=Portland,dc=example,dc=org
    objectClass: posixGroup
    gidNumber: 1000
    cn: logger
    memberUid: johndoe

Signed-off-by: Vitaliy Dmitriev <vi7alya@gmail.com>

Documentation/connectors/ldap.md

@@ -123,10 +123,11 @@ connectors:
       # Optional filter to apply when searching the directory.
       filter: "(objectClass=group)"
 
-      # Following two fields are used to match a user to a group. It adds an additional
+      # Following list contains field pairs that are used to match a user to a group. It adds an additional
       # requirement to the filter that an attribute in the group must match the user's
       # attribute value.
-      userAttr: uid
+      userMatchers:
+      - userAttr: uid
         groupAttr: member
 
       # Represents group name.
@@ -215,7 +216,8 @@ groupSearch:
 
   # The group search needs to match the "uid" attribute on
   # the user with the "memberUid" attribute on the group.
-  userAttr: uid
+  userMatchers:
+  - userAttr: uid
     groupAttr: memberUid
 
   # Unique name of the group.
@@ -242,7 +244,26 @@ groupSearch:
   # Optional filter to apply when searching the directory.
   filter: "(objectClass=group)"
 
-  userAttr: DN # Use "DN" here not "uid"
+  userMatchers:
+  - userAttr: DN # Use "DN" here not "uid"
+    groupAttr: member
+
+  nameAttr: name
+```
+
+There are cases when different types (objectClass) of groups use different attributes to keep a list of members. Below is an example of group query for such case:
+
+```yaml
+groupSearch:
+  baseDN: cn=groups,cn=compat,dc=example,dc=com
+  # Optional filter to search for different group types
+  filter: "(|(objectClass=posixGroup)(objectClass=group))"
+
+  # Use multiple user matchers so Dex will know which attribute names should be used to search for group members
+  userMatchers:
+  - userAttr: uid
+    groupAttr: memberUid
+  - userAttr: DN
     groupAttr: member
 
   nameAttr: name
@@ -275,7 +296,8 @@ connectors:
       # Would translate to the query "(&(objectClass=group)(member=<user uid>))".
       baseDN: cn=groups,dc=freeipa,dc=example,dc=com
       filter: "(objectClass=group)"
-      userAttr: uid
+      userMatchers:
+      - userAttr: uid
         groupAttr: member
       nameAttr: name
 ```
@@ -315,7 +337,8 @@ connectors:
     groupSearch:
       baseDN: cn=Users,dc=example,dc=com
       filter: "(objectClass=group)"
-      userAttr: DN
+      userMatchers:
+      - userAttr: DN
         groupAttr: member
       nameAttr: cn
 ```

connector/ldap/ldap.go

@@ -41,16 +41,26 @@ import (
 //         nameAttr: name
 //         preferredUsernameAttr: uid
 //       groupSearch:
-//         # Would translate to the query "(&(objectClass=group)(member=<user uid>))"
+//         # 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=group)"
+//         filter: "(|(objectClass=posixGroup)(objectClass=groupOfNames))"
-//         userAttr: uid
+//         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
+//           # Will only work if "DN" attribute does not exist in the record:
-//         # userAttr: DN
+//         - userAttr: DN
 //           groupAttr: member
 //         nameAttr: name
 //
+
+type UserMatcher struct {
+	UserAttr  string `json:"userAttr"`
+	GroupAttr string `json:"groupAttr"`
+}
+
 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.
@@ -124,16 +134,16 @@ type Config struct {
 
 		Scope string `json:"scope"` // Defaults to "sub"
 
-		// These two fields are use to match a user to a group.
+		// Array of the field pairs used to match a user to a group.
+		// See the "UserMatcher" struct for the exact field names
 		//
-		// It adds an additional requirement to the filter that an attribute in the group
+		// 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:
 		//
-		//   (<groupAttr>=<userAttr value>)
+		//   (userMatchers[n].<groupAttr>=userMatchers[n].<userAttr value>)
 		//
-		UserAttr  string `json:"userAttr"`
+		UserMatchers []UserMatcher `json:"userMatchers"`
-		GroupAttr string `json:"groupAttr"`
 
 		// The attribute of the group that represents its name.
 		NameAttr string `json:"nameAttr"`
@@ -378,11 +388,14 @@ func (c *ldapConnector) userEntry(conn *ldap.Conn, username string) (user ldap.E
 		Attributes: []string{
 			c.UserSearch.IDAttr,
 			c.UserSearch.EmailAttr,
-			c.GroupSearch.UserAttr,
 			// TODO(ericchiang): what if this contains duplicate values?
 		},
 	}
 
+	for _, matcher := range c.GroupSearch.UserMatchers {
+		req.Attributes = append(req.Attributes, matcher.UserAttr)
+	}
+
 	if c.UserSearch.NameAttr != "" {
 		req.Attributes = append(req.Attributes, c.UserSearch.NameAttr)
 	}
@@ -536,8 +549,9 @@ func (c *ldapConnector) groups(ctx context.Context, user ldap.Entry) ([]string,
 	}
 
 	var groups []*ldap.Entry
-	for _, attr := range getAttrs(user, c.GroupSearch.UserAttr) {
+	for _, matcher := range c.GroupSearch.UserMatchers {
-		filter := fmt.Sprintf("(%s=%s)", c.GroupSearch.GroupAttr, ldap.EscapeFilter(attr))
+		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)
 			}
@@ -568,6 +582,7 @@ func (c *ldapConnector) groups(ctx context.Context, user ldap.Entry) ([]string,
 				c.logger.Errorf("ldap: groups search with filter %q returned no groups", filter)
 			}
 		}
+	}
 
 	var groupNames []string
 	for _, group := range groups {

connector/ldap/ldap_test.go

@@ -307,8 +307,12 @@ member: cn=jane,ou=People,dc=example,dc=org
 	c.UserSearch.IDAttr = "DN"
 	c.UserSearch.Username = "cn"
 	c.GroupSearch.BaseDN = "ou=Groups,dc=example,dc=org"
-	c.GroupSearch.UserAttr = "DN"
+	c.GroupSearch.UserMatchers = []UserMatcher{
-	c.GroupSearch.GroupAttr = "member"
+		{
+			UserAttr:  "DN",
+			GroupAttr: "member",
+		},
+	}
 	c.GroupSearch.NameAttr = "cn"
 
 	tests := []subtest{
@@ -400,8 +404,12 @@ gidNumber: 1002
 	c.UserSearch.IDAttr = "DN"
 	c.UserSearch.Username = "cn"
 	c.GroupSearch.BaseDN = "ou=Groups,dc=example,dc=org"
-	c.GroupSearch.UserAttr = "departmentNumber"
+	c.GroupSearch.UserMatchers = []UserMatcher{
-	c.GroupSearch.GroupAttr = "gidNumber"
+		{
+			UserAttr:  "departmentNumber",
+			GroupAttr: "gidNumber",
+		},
+	}
 	c.GroupSearch.NameAttr = "cn"
 	tests := []subtest{
 		{
@@ -497,8 +505,12 @@ member: cn=jane,ou=People,dc=example,dc=org
 	c.UserSearch.IDAttr = "DN"
 	c.UserSearch.Username = "cn"
 	c.GroupSearch.BaseDN = "dc=example,dc=org"
-	c.GroupSearch.UserAttr = "DN"
+	c.GroupSearch.UserMatchers = []UserMatcher{
-	c.GroupSearch.GroupAttr = "member"
+		{
+			UserAttr:  "DN",
+			GroupAttr: "member",
+		},
+	}
 	c.GroupSearch.NameAttr = "cn"
 	c.GroupSearch.Filter = "(ou:dn:=Seattle)" // ignore other groups
 
@@ -534,6 +546,136 @@ member: cn=jane,ou=People,dc=example,dc=org
 	runTests(t, schema, connectLDAP, c, tests)
 }
 
+func TestGroupToUserMatchers(t *testing.T) {
+	schema := `
+dn: ou=People,dc=example,dc=org
+objectClass: organizationalUnit
+ou: People
+
+dn: cn=jane,ou=People,dc=example,dc=org
+objectClass: person
+objectClass: inetOrgPerson
+sn: doe
+cn: jane
+uid: janedoe
+mail: janedoe@example.com
+userpassword: foo
+
+dn: cn=john,ou=People,dc=example,dc=org
+objectClass: person
+objectClass: inetOrgPerson
+sn: doe
+cn: john
+uid: johndoe
+mail: johndoe@example.com
+userpassword: bar
+
+# Group definitions.
+
+dn: ou=Seattle,dc=example,dc=org
+objectClass: organizationalUnit
+ou: Seattle
+
+dn: ou=Portland,dc=example,dc=org
+objectClass: organizationalUnit
+ou: Portland
+
+dn: ou=Groups,ou=Seattle,dc=example,dc=org
+objectClass: organizationalUnit
+ou: Groups
+
+dn: ou=UnixGroups,ou=Seattle,dc=example,dc=org
+objectClass: organizationalUnit
+ou: UnixGroups
+
+dn: ou=Groups,ou=Portland,dc=example,dc=org
+objectClass: organizationalUnit
+ou: Groups
+
+dn: ou=UnixGroups,ou=Portland,dc=example,dc=org
+objectClass: organizationalUnit
+ou: UnixGroups
+
+dn: cn=qa,ou=Groups,ou=Portland,dc=example,dc=org
+objectClass: groupOfNames
+cn: qa
+member: cn=john,ou=People,dc=example,dc=org
+
+dn: cn=logger,ou=UnixGroups,ou=Portland,dc=example,dc=org
+objectClass: posixGroup
+gidNumber: 1000
+cn: logger
+memberUid: johndoe
+
+dn: cn=admins,ou=Groups,ou=Seattle,dc=example,dc=org
+objectClass: groupOfNames
+cn: admins
+member: cn=john,ou=People,dc=example,dc=org
+member: cn=jane,ou=People,dc=example,dc=org
+
+dn: cn=developers,ou=Groups,ou=Seattle,dc=example,dc=org
+objectClass: groupOfNames
+cn: developers
+member: cn=jane,ou=People,dc=example,dc=org
+
+dn: cn=frontend,ou=UnixGroups,ou=Seattle,dc=example,dc=org
+objectClass: posixGroup
+gidNumber: 1001
+cn: frontend
+memberUid: janedoe
+`
+	c := &Config{}
+	c.UserSearch.BaseDN = "ou=People,dc=example,dc=org"
+	c.UserSearch.NameAttr = "cn"
+	c.UserSearch.EmailAttr = "mail"
+	c.UserSearch.IDAttr = "DN"
+	c.UserSearch.Username = "cn"
+	c.GroupSearch.BaseDN = "dc=example,dc=org"
+	c.GroupSearch.UserMatchers = []UserMatcher{
+		{
+			UserAttr:  "DN",
+			GroupAttr: "member",
+		},
+		{
+			UserAttr:  "uid",
+			GroupAttr: "memberUid",
+		},
+	}
+	c.GroupSearch.NameAttr = "cn"
+	c.GroupSearch.Filter = "(|(objectClass=posixGroup)(objectClass=groupOfNames))" // search all group types
+
+	tests := []subtest{
+		{
+			name:     "validpassword",
+			username: "jane",
+			password: "foo",
+			groups:   true,
+			want: connector.Identity{
+				UserID:        "cn=jane,ou=People,dc=example,dc=org",
+				Username:      "jane",
+				Email:         "janedoe@example.com",
+				EmailVerified: true,
+				Groups:        []string{"admins", "developers", "frontend"},
+			},
+		},
+		{
+			name:     "validpassword2",
+			username: "john",
+			password: "bar",
+			groups:   true,
+			want: connector.Identity{
+				UserID:        "cn=john,ou=People,dc=example,dc=org",
+				Username:      "john",
+				Email:         "johndoe@example.com",
+				EmailVerified: true,
+				Groups:        []string{"qa", "admins", "logger"},
+			},
+		},
+	}
+
+	runTests(t, schema, connectLDAP, c, tests)
+}
+
 func TestStartTLS(t *testing.T) {
 	schema := `
 dn: ou=People,dc=example,dc=org

examples/config-ad-kubelogin.yaml

@@ -41,9 +41,10 @@ connectors:
       baseDN: cn=Users,dc=example,dc=com
       filter: "(objectClass=group)"
 
+      userMatchers:
       # A user is a member of a group when their DN matches
       # the value of a "member" attribute on the group entity.
-      userAttr: DN
+      - userAttr: DN
         groupAttr: member
 
       # The group name should be the "cn" value.

examples/config-ldap.yaml

@@ -37,9 +37,10 @@ connectors:
       baseDN: ou=Groups,dc=example,dc=org
       filter: "(objectClass=groupOfNames)"
 
+      userMatchers:
         # A user is a member of a group when their DN matches
         # the value of a "member" attribute on the group entity.
-      userAttr: DN
+      - userAttr: DN
         groupAttr: member
 
       # The group name should be the "cn" value.