Add LDAP group sync to Teams, fixes #1395 (#16299)

* Add setting for a JSON that maps LDAP groups to Org Teams.
* Add log when removing or adding team members.
* Sync is being run on login and periodically.
* Existing group filter settings are reused.
* Adding and removing team members.
* Sync not existing LDAP group.
* Login with broken group map JSON.

6 files changed, 244 insertions, 27 deletions

diff --git a/services/auth/source/ldap/README.md b/services/auth/source/ldap/README.md
index 3a839fa314..59fc5cabad 100644
--- a/services/auth/source/ldap/README.md
+++ b/services/auth/source/ldap/README.md
@@ -120,3 +120,11 @@ share the following fields:
 * Group Attribute for User (optional)
   * Which group LDAP attribute contains an array above user attribute names.
   * Example: memberUid
+
+* Team group map (optional)
+  * Automatically add users to Organization teams, depending on LDAP group memberships.
+  * Note: this function only adds users to teams, it never removes users.
+  * Example: {"cn=MyGroup,cn=groups,dc=example,dc=org": {"MyGiteaOrganization": ["MyGiteaTeam1", "MyGiteaTeam2", ...], ...}, ...}
+
+* Team group map removal (optional)
+  * If set to true, users will be removed from teams if they are not members of the corresponding group.
diff --git a/services/auth/source/ldap/source.go b/services/auth/source/ldap/source.go
index fc778b0114..ad97e2dd49 100644
--- a/services/auth/source/ldap/source.go
+++ b/services/auth/source/ldap/source.go
@@ -52,6 +52,8 @@ type Source struct {
 	GroupDN               string // Group Search Base
 	GroupFilter           string // Group Name Filter
 	GroupMemberUID        string // Group Attribute containing array of UserUID
+	GroupTeamMap          string // Map LDAP groups to teams
+	GroupTeamMapRemoval   bool   // Remove user from teams which are synchronized and user is not a member of the corresponding LDAP group
 	UserUID               string // User Attribute listed in Group
 	SkipLocalTwoFA        bool   `json:",omitempty"` // Skip Local 2fa for users authenticated with this source
 
diff --git a/services/auth/source/ldap/source_authenticate.go b/services/auth/source/ldap/source_authenticate.go
index 52971bb87e..e804e32e84 100644
--- a/services/auth/source/ldap/source_authenticate.go
+++ b/services/auth/source/ldap/source_authenticate.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"strings"
 
+	"code.gitea.io/gitea/models"
 	asymkey_model "code.gitea.io/gitea/models/asymkey"
 	"code.gitea.io/gitea/models/auth"
 	"code.gitea.io/gitea/models/db"
@@ -59,10 +60,14 @@ func (source *Source) Authenticate(user *user_model.User, userName, password str
 	}
 
 	if user != nil {
+		if source.GroupsEnabled && (source.GroupTeamMap != "" || source.GroupTeamMapRemoval) {
+			orgCache := make(map[string]*models.Organization)
+			teamCache := make(map[string]*models.Team)
+			source.SyncLdapGroupsToTeams(user, sr.LdapTeamAdd, sr.LdapTeamRemove, orgCache, teamCache)
+		}
 		if isAttributeSSHPublicKeySet && asymkey_model.SynchronizePublicKeys(user, source.authSource, sr.SSHPublicKey) {
 			return user, asymkey_model.RewriteAllPublicKeys()
 		}
-
 		return user, nil
 	}
 
@@ -98,10 +103,14 @@ func (source *Source) Authenticate(user *user_model.User, userName, password str
 	if isAttributeSSHPublicKeySet && asymkey_model.AddPublicKeysBySource(user, source.authSource, sr.SSHPublicKey) {
 		err = asymkey_model.RewriteAllPublicKeys()
 	}
-
 	if err == nil && len(source.AttributeAvatar) > 0 {
 		_ = user_service.UploadAvatar(user, sr.Avatar)
 	}
+	if source.GroupsEnabled && (source.GroupTeamMap != "" || source.GroupTeamMapRemoval) {
+		orgCache := make(map[string]*models.Organization)
+		teamCache := make(map[string]*models.Team)
+		source.SyncLdapGroupsToTeams(user, sr.LdapTeamAdd, sr.LdapTeamRemove, orgCache, teamCache)
+	}
 
 	return user, err
 }
diff --git a/services/auth/source/ldap/source_group_sync.go b/services/auth/source/ldap/source_group_sync.go
new file mode 100644
index 0000000000..7c62af705e
--- /dev/null
+++ b/services/auth/source/ldap/source_group_sync.go
@@ -0,0 +1,100 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package ldap
+
+import (
+	"code.gitea.io/gitea/models"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/log"
+)
+
+// SyncLdapGroupsToTeams maps LDAP groups to organization and team memberships
+func (source *Source) SyncLdapGroupsToTeams(user *user_model.User, ldapTeamAdd, ldapTeamRemove map[string][]string, orgCache map[string]*models.Organization, teamCache map[string]*models.Team) {
+	var err error
+	if source.GroupsEnabled && source.GroupTeamMapRemoval {
+		// when the user is not a member of configs LDAP group, remove mapped organizations/teams memberships
+		removeMappedMemberships(user, ldapTeamRemove, orgCache, teamCache)
+	}
+	for orgName, teamNames := range ldapTeamAdd {
+		org, ok := orgCache[orgName]
+		if !ok {
+			org, err = models.GetOrgByName(orgName)
+			if err != nil {
+				// organization must be created before LDAP group sync
+				log.Warn("LDAP group sync: Could not find organisation %s: %v", orgName, err)
+				continue
+			}
+			orgCache[orgName] = org
+		}
+		if isMember, err := models.IsOrganizationMember(org.ID, user.ID); !isMember && err == nil {
+			log.Trace("LDAP group sync: adding user [%s] to organization [%s]", user.Name, org.Name)
+			err = org.AddMember(user.ID)
+			if err != nil {
+				log.Error("LDAP group sync: Could not add user to organization: %v", err)
+				continue
+			}
+		}
+		for _, teamName := range teamNames {
+			team, ok := teamCache[orgName+teamName]
+			if !ok {
+				team, err = org.GetTeam(teamName)
+				if err != nil {
+					// team must be created before LDAP group sync
+					log.Warn("LDAP group sync: Could not find team %s: %v", teamName, err)
+					continue
+				}
+				teamCache[orgName+teamName] = team
+			}
+			if isMember, err := models.IsTeamMember(org.ID, team.ID, user.ID); !isMember && err == nil {
+				log.Trace("LDAP group sync: adding user [%s] to team [%s]", user.Name, org.Name)
+			} else {
+				continue
+			}
+			err := team.AddMember(user.ID)
+			if err != nil {
+				log.Error("LDAP group sync: Could not add user to team: %v", err)
+			}
+		}
+	}
+}
+
+// remove membership to organizations/teams if user is not member of corresponding LDAP group
+// e.g. lets assume user is member of LDAP group "x", but LDAP group team map contains LDAP groups "x" and "y"
+// then users membership gets removed for all organizations/teams mapped by LDAP group "y"
+func removeMappedMemberships(user *user_model.User, ldapTeamRemove map[string][]string, orgCache map[string]*models.Organization, teamCache map[string]*models.Team) {
+	var err error
+	for orgName, teamNames := range ldapTeamRemove {
+		org, ok := orgCache[orgName]
+		if !ok {
+			org, err = models.GetOrgByName(orgName)
+			if err != nil {
+				// organization must be created before LDAP group sync
+				log.Warn("LDAP group sync: Could not find organisation %s: %v", orgName, err)
+				continue
+			}
+			orgCache[orgName] = org
+		}
+		for _, teamName := range teamNames {
+			team, ok := teamCache[orgName+teamName]
+			if !ok {
+				team, err = org.GetTeam(teamName)
+				if err != nil {
+					// team must must be created before LDAP group sync
+					log.Warn("LDAP group sync: Could not find team %s: %v", teamName, err)
+					continue
+				}
+			}
+			if isMember, err := models.IsTeamMember(org.ID, team.ID, user.ID); isMember && err == nil {
+				log.Trace("LDAP group sync: removing user [%s] from team [%s]", user.Name, org.Name)
+			} else {
+				continue
+			}
+			err = team.RemoveMember(user.ID)
+			if err != nil {
+				log.Error("LDAP group sync: Could not remove user from team: %v", err)
+			}
+		}
+	}
+}
diff --git a/services/auth/source/ldap/source_search.go b/services/auth/source/ldap/source_search.go
index 1f1cca270d..f2b940cabe 100644
--- a/services/auth/source/ldap/source_search.go
+++ b/services/auth/source/ldap/source_search.go
@@ -12,22 +12,26 @@ import (
 	"strconv"
 	"strings"
 
+	"code.gitea.io/gitea/modules/json"
 	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/util"
 
 	"github.com/go-ldap/ldap/v3"
 )
 
 // SearchResult : user data
 type SearchResult struct {
-	Username     string   // Username
-	Name         string   // Name
-	Surname      string   // Surname
-	Mail         string   // E-mail address
-	SSHPublicKey []string // SSH Public Key
-	IsAdmin      bool     // if user is administrator
-	IsRestricted bool     // if user is restricted
-	LowerName    string   // Lowername
-	Avatar       []byte
+	Username       string   // Username
+	Name           string   // Name
+	Surname        string   // Surname
+	Mail           string   // E-mail address
+	SSHPublicKey   []string // SSH Public Key
+	IsAdmin        bool     // if user is administrator
+	IsRestricted   bool     // if user is restricted
+	LowerName      string   // LowerName
+	Avatar         []byte
+	LdapTeamAdd    map[string][]string // organizations teams to add
+	LdapTeamRemove map[string][]string // organizations teams to remove
 }
 
 func (ls *Source) sanitizedUserQuery(username string) (string, bool) {
@@ -192,6 +196,71 @@ func checkRestricted(l *ldap.Conn, ls *Source, userDN string) bool {
 	return false
 }
 
+// List all group memberships of a user
+func (ls *Source) listLdapGroupMemberships(l *ldap.Conn, uid string) []string {
+	var ldapGroups []string
+	groupFilter := fmt.Sprintf("(%s=%s)", ls.GroupMemberUID, uid)
+	result, err := l.Search(ldap.NewSearchRequest(
+		ls.GroupDN,
+		ldap.ScopeWholeSubtree,
+		ldap.NeverDerefAliases,
+		0,
+		0,
+		false,
+		groupFilter,
+		[]string{},
+		nil,
+	))
+	if err != nil {
+		log.Error("Failed group search using filter[%s]: %v", groupFilter, err)
+		return ldapGroups
+	}
+
+	for _, entry := range result.Entries {
+		if entry.DN == "" {
+			log.Error("LDAP search was successful, but found no DN!")
+			continue
+		}
+		ldapGroups = append(ldapGroups, entry.DN)
+	}
+
+	return ldapGroups
+}
+
+// parse LDAP groups and return map of ldap groups to organizations teams
+func (ls *Source) mapLdapGroupsToTeams() map[string]map[string][]string {
+	ldapGroupsToTeams := make(map[string]map[string][]string)
+	err := json.Unmarshal([]byte(ls.GroupTeamMap), &ldapGroupsToTeams)
+	if err != nil {
+		log.Error("Failed to unmarshall LDAP teams map: %v", err)
+		return ldapGroupsToTeams
+	}
+	return ldapGroupsToTeams
+}
+
+// getMappedMemberships : returns the organizations and teams to modify the users membership
+func (ls *Source) getMappedMemberships(l *ldap.Conn, uid string) (map[string][]string, map[string][]string) {
+	// get all LDAP group memberships for user
+	usersLdapGroups := ls.listLdapGroupMemberships(l, uid)
+	// unmarshall LDAP group team map from configs
+	ldapGroupsToTeams := ls.mapLdapGroupsToTeams()
+	membershipsToAdd := map[string][]string{}
+	membershipsToRemove := map[string][]string{}
+	for group, memberships := range ldapGroupsToTeams {
+		isUserInGroup := util.IsStringInSlice(group, usersLdapGroups)
+		if isUserInGroup {
+			for org, teams := range memberships {
+				membershipsToAdd[org] = teams
+			}
+		} else if !isUserInGroup {
+			for org, teams := range memberships {
+				membershipsToRemove[org] = teams
+			}
+		}
+	}
+	return membershipsToAdd, membershipsToRemove
+}
+
 // SearchEntry : search an LDAP source if an entry (name, passwd) is valid and in the specific filter
 func (ls *Source) SearchEntry(name, passwd string, directBind bool) *SearchResult {
 	// See https://tools.ietf.org/search/rfc4513#section-5.1.2
@@ -308,9 +377,12 @@ func (ls *Source) SearchEntry(name, passwd string, directBind bool) *SearchResul
 	surname := sr.Entries[0].GetAttributeValue(ls.AttributeSurname)
 	mail := sr.Entries[0].GetAttributeValue(ls.AttributeMail)
 	uid := sr.Entries[0].GetAttributeValue(ls.UserUID)
+	if ls.UserUID == "dn" || ls.UserUID == "DN" {
+		uid = sr.Entries[0].DN
+	}
 
 	// Check group membership
-	if ls.GroupsEnabled {
+	if ls.GroupsEnabled && ls.GroupFilter != "" {
 		groupFilter, ok := ls.sanitizedGroupFilter(ls.GroupFilter)
 		if !ok {
 			return nil
@@ -373,16 +445,24 @@ func (ls *Source) SearchEntry(name, passwd string, directBind bool) *SearchResul
 		Avatar = sr.Entries[0].GetRawAttributeValue(ls.AttributeAvatar)
 	}
 
+	teamsToAdd := make(map[string][]string)
+	teamsToRemove := make(map[string][]string)
+	if ls.GroupsEnabled && (ls.GroupTeamMap != "" || ls.GroupTeamMapRemoval) {
+		teamsToAdd, teamsToRemove = ls.getMappedMemberships(l, uid)
+	}
+
 	return &SearchResult{
-		LowerName:    strings.ToLower(username),
-		Username:     username,
-		Name:         firstname,
-		Surname:      surname,
-		Mail:         mail,
-		SSHPublicKey: sshPublicKey,
-		IsAdmin:      isAdmin,
-		IsRestricted: isRestricted,
-		Avatar:       Avatar,
+		LowerName:      strings.ToLower(username),
+		Username:       username,
+		Name:           firstname,
+		Surname:        surname,
+		Mail:           mail,
+		SSHPublicKey:   sshPublicKey,
+		IsAdmin:        isAdmin,
+		IsRestricted:   isRestricted,
+		Avatar:         Avatar,
+		LdapTeamAdd:    teamsToAdd,
+		LdapTeamRemove: teamsToRemove,
 	}
 }
 
@@ -417,7 +497,7 @@ func (ls *Source) SearchEntries() ([]*SearchResult, error) {
 	isAttributeSSHPublicKeySet := len(strings.TrimSpace(ls.AttributeSSHPublicKey)) > 0
 	isAtributeAvatarSet := len(strings.TrimSpace(ls.AttributeAvatar)) > 0
 
-	attribs := []string{ls.AttributeUsername, ls.AttributeName, ls.AttributeSurname, ls.AttributeMail}
+	attribs := []string{ls.AttributeUsername, ls.AttributeName, ls.AttributeSurname, ls.AttributeMail, ls.UserUID}
 	if isAttributeSSHPublicKeySet {
 		attribs = append(attribs, ls.AttributeSSHPublicKey)
 	}
@@ -444,12 +524,23 @@ func (ls *Source) SearchEntries() ([]*SearchResult, error) {
 	result := make([]*SearchResult, len(sr.Entries))
 
 	for i, v := range sr.Entries {
+		teamsToAdd := make(map[string][]string)
+		teamsToRemove := make(map[string][]string)
+		if ls.GroupsEnabled && (ls.GroupTeamMap != "" || ls.GroupTeamMapRemoval) {
+			userAttributeListedInGroup := v.GetAttributeValue(ls.UserUID)
+			if ls.UserUID == "dn" || ls.UserUID == "DN" {
+				userAttributeListedInGroup = v.DN
+			}
+			teamsToAdd, teamsToRemove = ls.getMappedMemberships(l, userAttributeListedInGroup)
+		}
 		result[i] = &SearchResult{
-			Username: v.GetAttributeValue(ls.AttributeUsername),
-			Name:     v.GetAttributeValue(ls.AttributeName),
-			Surname:  v.GetAttributeValue(ls.AttributeSurname),
-			Mail:     v.GetAttributeValue(ls.AttributeMail),
-			IsAdmin:  checkAdmin(l, ls, v.DN),
+			Username:       v.GetAttributeValue(ls.AttributeUsername),
+			Name:           v.GetAttributeValue(ls.AttributeName),
+			Surname:        v.GetAttributeValue(ls.AttributeSurname),
+			Mail:           v.GetAttributeValue(ls.AttributeMail),
+			IsAdmin:        checkAdmin(l, ls, v.DN),
+			LdapTeamAdd:    teamsToAdd,
+			LdapTeamRemove: teamsToRemove,
 		}
 		if !result[i].IsAdmin {
 			result[i].IsRestricted = checkRestricted(l, ls, v.DN)
diff --git a/services/auth/source/ldap/source_sync.go b/services/auth/source/ldap/source_sync.go
index 398d9ef798..74a62ce4e7 100644
--- a/services/auth/source/ldap/source_sync.go
+++ b/services/auth/source/ldap/source_sync.go
@@ -10,6 +10,7 @@ import (
 	"sort"
 	"strings"
 
+	"code.gitea.io/gitea/models"
 	asymkey_model "code.gitea.io/gitea/models/asymkey"
 	"code.gitea.io/gitea/models/db"
 	user_model "code.gitea.io/gitea/models/user"
@@ -61,6 +62,8 @@ func (source *Source) Sync(ctx context.Context, updateExisting bool) error {
 	})
 
 	userPos := 0
+	orgCache := make(map[string]*models.Organization)
+	teamCache := make(map[string]*models.Team)
 
 	for _, su := range sr {
 		select {
@@ -166,6 +169,10 @@ func (source *Source) Sync(ctx context.Context, updateExisting bool) error {
 				}
 			}
 		}
+		// Synchronize LDAP groups with organization and team memberships
+		if source.GroupsEnabled && (source.GroupTeamMap != "" || source.GroupTeamMapRemoval) {
+			source.SyncLdapGroupsToTeams(usr, su.LdapTeamAdd, su.LdapTeamRemove, orgCache, teamCache)
+		}
 	}
 
 	// Rewrite authorized_keys file if LDAP Public SSH Key attribute is set and any key was added or removed