diff options
Diffstat (limited to 'main.go')
| -rw-r--r-- | main.go | 328 |
1 files changed, 328 insertions, 0 deletions
@@ -0,0 +1,328 @@ +package main + +import ( + "encoding/json" + "errors" + "flag" + "fmt" + "github.com/msteinert/pam" + "github.com/nmcclain/asn1-ber" + "github.com/nmcclain/ldap" + "log" + "net" + "os" + "os/user" + "strings" +) + +type Backend struct { + ldap.Binder + ldap.Searcher + ldap.Closer + logger *log.Logger + Listen string + PAMServiceName string + PeopleDN string + GroupsDN string + BindAdminDN string + BindAdminPassword string +} + +func main() { + var configfile = flag.String("c", "pamldapd.json", "Configuration file") + var logfile = flag.String("l", "", "Log file (STDOUT if blank)") + flag.Parse() + var backend = Backend{} + { + confighandle, err := os.Open(*configfile) + if err != nil { + fmt.Printf("Could not read: %s\n", err) + os.Exit(1) + } + decoder := json.NewDecoder(confighandle) + if err := decoder.Decode(&backend); err != nil { + fmt.Printf("Could not decode configuration configfile %s: %s\n", *configfile, err) + confighandle.Close() + os.Exit(1) + } + confighandle.Close() + } + if *logfile == "" { + backend.logger = log.New(os.Stdout, "", log.LstdFlags) + } else { + loghandle, err := os.OpenFile(*logfile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0600) + if err != nil { + fmt.Printf("Could not open log file: %s\n", err) + os.Exit(1) + } + defer loghandle.Close() + log.SetOutput(loghandle) + backend.logger = log.New(loghandle, "", log.LstdFlags) + } + + current_user, err := user.Current() + if err != nil { + fmt.Printf("Could not get current user: %s\n", err) + os.Exit(1) + } + if current_user.Uid != "0" { + backend.logger.Printf("WARNING: PAM authentication will fail because not running as root user") + } + + l := ldap.NewServer() + l.EnforceLDAP = true + l.BindFunc("", backend) + l.SearchFunc("", backend) + l.CloseFunc("", backend) + backend.logger.Printf("LDAP server listen: %s", backend.Listen) + if err := l.ListenAndServe(backend.Listen); err != nil { + backend.logger.Printf("LDAP server listen failed: %s", err.Error()) + os.Exit(1) + } +} + +func (b Backend) Bind(bindDN, bindSimplePw string, conn net.Conn) (resultCode ldap.LDAPResultCode, err error) { + var logger_title = fmt.Sprintf("Bind addr=%s bindDN=%s", conn.RemoteAddr().String(), bindDN) + b.logger.Printf("%s begin", logger_title) + if bindDN == b.BindAdminDN { + if bindSimplePw != b.BindAdminPassword { + return ldap.LDAPResultInvalidCredentials, errors.New("Password Incorrect") + } + b.logger.Printf("%s success as administrator", logger_title) + return ldap.LDAPResultSuccess, nil + } else { + var username string + if username, err = b.getUserNameFromBindDN(bindDN); err != nil { + return ldap.LDAPResultInvalidCredentials, err + } + if err := PAMAuth(b.PAMServiceName, username, bindSimplePw); err != nil { + return ldap.LDAPResultInvalidCredentials, err + } + b.logger.Printf("%s success as normal user", logger_title) + return ldap.LDAPResultSuccess, nil + } +} + +func (b Backend) Search(bindDN string, req ldap.SearchRequest, conn net.Conn) (result ldap.ServerSearchResult, err error) { + var logger_title = fmt.Sprintf("Search bindDN=%s baseDN=%s filter=%s addr=%s", bindDN, req.BaseDN, req.Filter, conn.RemoteAddr().String()) + b.logger.Printf("%s begin", logger_title) + filterObjectClass, err := ldap.GetFilterObjectClass(req.Filter) + if err != nil { + return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, fmt.Errorf("%s error parsing ObjectClass: %s", logger_title, req.Filter) + } + var username string + var user_entity_name string + if filterObjectClass == "posixaccount" || filterObjectClass == "" { + user_entity_name = "uid" + } else if filterObjectClass == "posixgroup" { + user_entity_name = "memberUid" + } else { + return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, fmt.Errorf("%s error: Filter does not contain objectclass=posixaccount nor objectclass=posixgroup", logger_title) + } + + if bindDN == b.BindAdminDN { + filterUid, err := GetFilterEntity(user_entity_name, req.Filter) + if err != nil { + return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, fmt.Errorf("%s error find condition uid: %s", logger_title, req.Filter) + } + if binddn_username, err := b.getUserNameFromBaseDN(req.BaseDN); err == nil { + username = binddn_username + } else { + username = filterUid + } + } else { + if username, err = b.getUserNameFromBindDN(bindDN); err != nil { + return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, err + } + } + if req.BaseDN == "" { + return ldap.ServerSearchResult{make([]*ldap.Entry, 0), []string{}, []ldap.Control{}, ldap.LDAPResultSuccess}, nil + } + var entry *ldap.Entry + if filterObjectClass == "posixaccount" || filterObjectClass == "" { + if entry, err = b.makeSearchEntryAccount("cn="+username+","+b.PeopleDN, username); err != nil { + return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, err + } + } else if filterObjectClass == "posixgroup" { + if entry, err = b.makeSearchEntryGroup(b.GroupsDN, username); err != nil { + return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, err + } + } else { + return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, fmt.Errorf("%s error: Filter does not contain objectclass=posixaccount nor objectclass=posixgroup", logger_title) + } + return ldap.ServerSearchResult{[]*ldap.Entry{entry}, []string{}, []ldap.Control{}, ldap.LDAPResultSuccess}, nil + + return ldap.ServerSearchResult{make([]*ldap.Entry, 0), []string{}, []ldap.Control{}, ldap.LDAPResultSuccess}, nil +} + +func (b Backend) Close(bindDN string, conn net.Conn) (err error) { + b.logger.Printf("Close addr=%s", conn.RemoteAddr().String()) + return nil +} + +func PAMAuth(serviceName, userName, passwd string) error { + t, err := pam.StartFunc(serviceName, userName, func(s pam.Style, msg string) (string, error) { + switch s { + case pam.PromptEchoOff: + return passwd, nil + case pam.PromptEchoOn, pam.ErrorMsg, pam.TextInfo: + return "", nil + } + return "", errors.New("Unrecognized PAM message style") + }) + + if err != nil { + return err + } + + if err = t.Authenticate(0); err != nil { + return err + } + + return nil +} + +func (b Backend) getUserNameFromBindDN(bindDN string) (username string, err error) { + if bindDN == "" { + return "", errors.New("bindDN not specified") + } + if !strings.HasSuffix(bindDN, ","+b.PeopleDN) { + return "", errors.New("bindDN not matched") + } + rest := strings.TrimSuffix(bindDN, ","+b.PeopleDN) + if rest == "" { + return "", errors.New("bindDN format error") + } + if strings.Contains(rest, ",") { + return "", errors.New("bindDN has too much entities") + } + if strings.HasPrefix(rest, "uid=") { + username = strings.TrimPrefix(rest, "uid=") + } else if strings.HasPrefix(rest, "cn=") { + username = strings.TrimPrefix(rest, "cn=") + } else { + return "", errors.New("bindDN contains no cn/uid entry") + } + return username, nil +} + +func (b Backend) getUserNameFromBaseDN(baseDN string) (username string, err error) { + if baseDN == "" { + return "", errors.New("baseDN not specified") + } + if !strings.HasSuffix(baseDN, ","+b.PeopleDN) { + return "", errors.New("baseDN not matched") + } + rest := strings.TrimSuffix(baseDN, ","+b.PeopleDN) + if rest == "" { + return "", errors.New("baseDN format error") + } + if strings.Contains(rest, ",") { + return "", errors.New("baseDN has too much entities") + } + if strings.HasPrefix(rest, "uid=") { + username = strings.TrimPrefix(rest, "uid=") + } else if strings.HasPrefix(rest, "cn=") { + username = strings.TrimPrefix(rest, "cn=") + } else { + return "", errors.New("baseDN contains no cn/uid entry") + } + return username, nil +} + +func (b Backend) makeSearchEntryAccount(dn string, username string) (entry *ldap.Entry, err error) { + attrs := []*ldap.EntryAttribute{} + var u *user.User + if u, err = user.Lookup(username); err != nil { + return entry, err + } + attrs = append(attrs, &ldap.EntryAttribute{"objectClass", []string{"posixAccount"}}) + attrs = append(attrs, &ldap.EntryAttribute{"cn", []string{username}}) + attrs = append(attrs, &ldap.EntryAttribute{"uid", []string{username}}) + attrs = append(attrs, &ldap.EntryAttribute{"uidNumber", []string{u.Uid}}) + attrs = append(attrs, &ldap.EntryAttribute{"givenName", []string{u.Name}}) + attrs = append(attrs, &ldap.EntryAttribute{"gidNumber", []string{u.Gid}}) + attrs = append(attrs, &ldap.EntryAttribute{"homeDirectory", []string{u.HomeDir}}) + + entry = &ldap.Entry{dn, attrs} + return entry, nil +} + +func (b Backend) makeSearchEntryGroup(basedn string, username string) (entry *ldap.Entry, err error) { + attrs := []*ldap.EntryAttribute{} + var ( + u *user.User + g *user.Group + ) + if u, err = user.Lookup(username); err != nil { + return entry, err + } + if g, err = user.LookupGroupId(u.Gid); err != nil { + return entry, err + } + + attrs = append(attrs, &ldap.EntryAttribute{"objectClass", []string{"posixGroup"}}) + attrs = append(attrs, &ldap.EntryAttribute{"cn", []string{g.Name}}) + attrs = append(attrs, &ldap.EntryAttribute{"gidNumber", []string{u.Gid}}) + attrs = append(attrs, &ldap.EntryAttribute{"memberUid", []string{username}}) + + dn := "cn=" + g.Name + "," + basedn + entry = &ldap.Entry{dn, attrs} + return entry, nil +} + +func GetFilterEntity(entity string, filter string) (string, error) { + f, err := ldap.CompileFilter(filter) + if err != nil { + return "", err + } + return parseFilterEntity(entity, f) +} + +func parseFilterEntity(entity string, f *ber.Packet) (string, error) { + foundEntity := "" + switch ldap.FilterMap[f.Tag] { + case "Equality Match": + if len(f.Children) != 2 { + return "", errors.New("Equality match must have only two children") + } + attribute := strings.ToLower(f.Children[0].Value.(string)) + value := f.Children[1].Value.(string) + if attribute == entity { + foundEntity = strings.ToLower(value) + } + case "And": + for _, child := range f.Children { + subType, err := parseFilterEntity(entity, child) + if err != nil { + return "", err + } + if len(subType) > 0 { + foundEntity = subType + } + } + case "Or": + for _, child := range f.Children { + subType, err := parseFilterEntity(entity, child) + if err != nil { + return "", err + } + if len(subType) > 0 { + foundEntity = subType + } + } + case "Not": + if len(f.Children) != 1 { + return "", errors.New("Not filter must have only one child") + } + subType, err := parseFilterEntity(entity, f.Children[0]) + if err != nil { + return "", err + } + if len(subType) > 0 { + foundEntity = subType + } + + } + return strings.ToLower(foundEntity), nil +} |