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ftpd.go
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ftpd.go
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// Copyright (C) 2019 Nicola Murino
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, version 3.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
// Package ftpd implements the FTP protocol
package ftpd
import (
"context"
"errors"
"fmt"
"net"
"os"
"path/filepath"
"strings"
"time"
ftpserver "github.com/fclairamb/ftpserverlib"
"github.com/drakkan/sftpgo/v2/internal/common"
"github.com/drakkan/sftpgo/v2/internal/dataprovider"
"github.com/drakkan/sftpgo/v2/internal/logger"
"github.com/drakkan/sftpgo/v2/internal/util"
)
const (
logSender = "ftpd"
)
var (
certMgr *common.CertManager
serviceStatus ServiceStatus
)
// PassiveIPOverride defines an exception for the configured passive IP
type PassiveIPOverride struct {
Networks []string `json:"networks" mapstructure:"networks"`
// if empty the local address will be returned
IP string `json:"ip" mapstructure:"ip"`
parsedNetworks []func(net.IP) bool
}
// GetNetworksAsString returns the configured networks as string
func (p *PassiveIPOverride) GetNetworksAsString() string {
return strings.Join(p.Networks, ", ")
}
// Binding defines the configuration for a network listener
type Binding struct {
// The address to listen on. A blank value means listen on all available network interfaces.
Address string `json:"address" mapstructure:"address"`
// The port used for serving requests
Port int `json:"port" mapstructure:"port"`
// Apply the proxy configuration, if any, for this binding
ApplyProxyConfig bool `json:"apply_proxy_config" mapstructure:"apply_proxy_config"`
// Set to 1 to require TLS for both data and control connection.
// Set to 2 to enable implicit TLS
TLSMode int `json:"tls_mode" mapstructure:"tls_mode"`
// 0 disabled, 1 required
TLSSessionReuse int `json:"tls_session_reuse" mapstructure:"tls_session_reuse"`
// Certificate and matching private key for this specific binding, if empty the global
// ones will be used, if any
CertificateFile string `json:"certificate_file" mapstructure:"certificate_file"`
CertificateKeyFile string `json:"certificate_key_file" mapstructure:"certificate_key_file"`
// Defines the minimum TLS version. 13 means TLS 1.3, default is TLS 1.2
MinTLSVersion int `json:"min_tls_version" mapstructure:"min_tls_version"`
// External IP address for passive connections.
ForcePassiveIP string `json:"force_passive_ip" mapstructure:"force_passive_ip"`
// PassiveIPOverrides allows to define different IP addresses for passive connections
// based on the client IP address
PassiveIPOverrides []PassiveIPOverride `json:"passive_ip_overrides" mapstructure:"passive_ip_overrides"`
// Hostname for passive connections. This hostname will be resolved each time a passive
// connection is requested and this can, depending on the DNS configuration, take a noticeable
// amount of time. Enable this setting only if you have a dynamic IP address
PassiveHost string `json:"passive_host" mapstructure:"passive_host"`
// Set to 1 to require client certificate authentication.
// Set to 2 to require a client certificate and verfify it if given. In this mode
// the client is allowed not to send a certificate.
// You need to define at least a certificate authority for this to work
ClientAuthType int `json:"client_auth_type" mapstructure:"client_auth_type"`
// TLSCipherSuites is a list of supported cipher suites for TLS version 1.2.
// If CipherSuites is nil/empty, a default list of secure cipher suites
// is used, with a preference order based on hardware performance.
// Note that TLS 1.3 ciphersuites are not configurable.
// The supported ciphersuites names are defined here:
//
// https://github.com/golang/go/blob/master/src/crypto/tls/cipher_suites.go#L53
//
// any invalid name will be silently ignored.
// The order matters, the ciphers listed first will be the preferred ones.
TLSCipherSuites []string `json:"tls_cipher_suites" mapstructure:"tls_cipher_suites"`
// PassiveConnectionsSecurity defines the security checks for passive data connections.
// Supported values:
// - 0 require matching peer IP addresses of control and data connection. This is the default
// - 1 disable any checks
PassiveConnectionsSecurity int `json:"passive_connections_security" mapstructure:"passive_connections_security"`
// ActiveConnectionsSecurity defines the security checks for active data connections.
// The supported values are the same as described for PassiveConnectionsSecurity.
// Please note that disabling the security checks you will make the FTP service vulnerable to bounce attacks
// on active data connections, so change the default value only if you are on a trusted/internal network
ActiveConnectionsSecurity int `json:"active_connections_security" mapstructure:"active_connections_security"`
// Set to 1 to silently ignore any client requests to perform ASCII translations via the TYPE command.
// That is, FTP clients can request ASCII translations, and SFTPGo will respond as the client expects,
// but will not actually perform the translation for either uploads or downloads. This behavior can be
// useful in circumstances involving older/mainframe clients and EBCDIC files.
IgnoreASCIITransferType int `json:"ignore_ascii_transfer_type" mapstructure:"ignore_ascii_transfer_type"`
// Debug enables the FTP debug mode. In debug mode, every FTP command will be logged
Debug bool `json:"debug" mapstructure:"debug"`
ciphers []uint16
}
func (b *Binding) setCiphers() {
b.ciphers = util.GetTLSCiphersFromNames(b.TLSCipherSuites)
}
func (b *Binding) isMutualTLSEnabled() bool {
return b.ClientAuthType == 1 || b.ClientAuthType == 2
}
// GetAddress returns the binding address
func (b *Binding) GetAddress() string {
return fmt.Sprintf("%s:%d", b.Address, b.Port)
}
// IsValid returns true if the binding port is > 0
func (b *Binding) IsValid() bool {
return b.Port > 0
}
func (b *Binding) isTLSModeValid() bool {
return b.TLSMode >= 0 && b.TLSMode <= 2
}
func (b *Binding) isTLSSessionReuseValid() bool {
return b.TLSSessionReuse >= 0 && b.TLSSessionReuse <= 1
}
func (b *Binding) checkSecuritySettings() error {
if b.PassiveConnectionsSecurity < 0 || b.PassiveConnectionsSecurity > 1 {
return fmt.Errorf("invalid passive_connections_security: %v", b.PassiveConnectionsSecurity)
}
if b.ActiveConnectionsSecurity < 0 || b.ActiveConnectionsSecurity > 1 {
return fmt.Errorf("invalid active_connections_security: %v", b.ActiveConnectionsSecurity)
}
return nil
}
func (b *Binding) checkPassiveIP() error {
if b.ForcePassiveIP != "" {
ip, err := parsePassiveIP(b.ForcePassiveIP)
if err != nil {
return err
}
b.ForcePassiveIP = ip
}
for idx, passiveOverride := range b.PassiveIPOverrides {
var ip string
if passiveOverride.IP != "" {
var err error
ip, err = parsePassiveIP(passiveOverride.IP)
if err != nil {
return err
}
}
if len(passiveOverride.Networks) == 0 {
return errors.New("passive IP networks override cannot be empty")
}
checkFuncs, err := util.ParseAllowedIPAndRanges(passiveOverride.Networks)
if err != nil {
return fmt.Errorf("invalid passive IP networks override %+v: %w", passiveOverride.Networks, err)
}
b.PassiveIPOverrides[idx].IP = ip
b.PassiveIPOverrides[idx].parsedNetworks = checkFuncs
}
return nil
}
func (b *Binding) getPassiveIP(cc ftpserver.ClientContext) (string, error) {
if b.ForcePassiveIP != "" {
return b.ForcePassiveIP, nil
}
if b.PassiveHost != "" {
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
addrs, err := net.DefaultResolver.LookupIP(ctx, "ip4", b.PassiveHost)
if err != nil {
logger.Error(logSender, "", "unable to resolve hostname %q: %v", b.PassiveHost, err)
return "", fmt.Errorf("unable to resolve hostname %q: %w", b.PassiveHost, err)
}
if len(addrs) > 0 {
return addrs[0].String(), nil
}
}
return strings.Split(cc.LocalAddr().String(), ":")[0], nil
}
func (b *Binding) passiveIPResolver(cc ftpserver.ClientContext) (string, error) {
if len(b.PassiveIPOverrides) > 0 {
clientIP := net.ParseIP(util.GetIPFromRemoteAddress(cc.RemoteAddr().String()))
if clientIP != nil {
for _, override := range b.PassiveIPOverrides {
for _, fn := range override.parsedNetworks {
if fn(clientIP) {
if override.IP == "" {
return strings.Split(cc.LocalAddr().String(), ":")[0], nil
}
return override.IP, nil
}
}
}
}
}
return b.getPassiveIP(cc)
}
// HasProxy returns true if the proxy protocol is active for this binding
func (b *Binding) HasProxy() bool {
return b.ApplyProxyConfig && common.Config.ProxyProtocol > 0
}
// GetTLSDescription returns the TLS mode as string
func (b *Binding) GetTLSDescription() string {
if certMgr == nil {
return util.I18nFTPTLSDisabled
}
switch b.TLSMode {
case 1:
return util.I18nFTPTLSExplicit
case 2:
return util.I18nFTPTLSImplicit
}
if certMgr.HasCertificate(common.DefaultTLSKeyPaidID) || certMgr.HasCertificate(b.GetAddress()) {
return util.I18nFTPTLSMixed
}
return util.I18nFTPTLSDisabled
}
// PortRange defines a port range
type PortRange struct {
// Range start
Start int `json:"start" mapstructure:"start"`
// Range end
End int `json:"end" mapstructure:"end"`
}
// ServiceStatus defines the service status
type ServiceStatus struct {
IsActive bool `json:"is_active"`
Bindings []Binding `json:"bindings"`
PassivePortRange PortRange `json:"passive_port_range"`
}
// Configuration defines the configuration for the ftp server
type Configuration struct {
// Addresses and ports to bind to
Bindings []Binding `json:"bindings" mapstructure:"bindings"`
// The contents of the specified file, if any, are diplayed when someone connects to the server.
BannerFile string `json:"banner_file" mapstructure:"banner_file"`
// If files containing a certificate and matching private key for the server are provided the server will accept
// both plain FTP an explicit FTP over TLS.
// Certificate and key files can be reloaded on demand sending a "SIGHUP" signal on Unix based systems and a
// "paramchange" request to the running service on Windows.
CertificateFile string `json:"certificate_file" mapstructure:"certificate_file"`
CertificateKeyFile string `json:"certificate_key_file" mapstructure:"certificate_key_file"`
// CACertificates defines the set of root certificate authorities to be used to verify client certificates.
CACertificates []string `json:"ca_certificates" mapstructure:"ca_certificates"`
// CARevocationLists defines a set a revocation lists, one for each root CA, to be used to check
// if a client certificate has been revoked
CARevocationLists []string `json:"ca_revocation_lists" mapstructure:"ca_revocation_lists"`
// Do not impose the port 20 for active data transfer. Enabling this option allows to run SFTPGo with less privilege
ActiveTransfersPortNon20 bool `json:"active_transfers_port_non_20" mapstructure:"active_transfers_port_non_20"`
// Set to true to disable active FTP
DisableActiveMode bool `json:"disable_active_mode" mapstructure:"disable_active_mode"`
// Set to true to enable the FTP SITE command.
// We support chmod and symlink if SITE support is enabled
EnableSite bool `json:"enable_site" mapstructure:"enable_site"`
// Set to 1 to enable FTP commands that allow to calculate the hash value of files.
// These FTP commands will be enabled: HASH, XCRC, MD5/XMD5, XSHA/XSHA1, XSHA256, XSHA512.
// Please keep in mind that to calculate the hash we need to read the whole file, for
// remote backends this means downloading the file, for the encrypted backend this means
// decrypting the file
HASHSupport int `json:"hash_support" mapstructure:"hash_support"`
// Set to 1 to enable support for the non standard "COMB" FTP command.
// Combine is only supported for local filesystem, for cloud backends it has
// no advantage as it will download the partial files and will upload the
// combined one. Cloud backends natively support multipart uploads.
CombineSupport int `json:"combine_support" mapstructure:"combine_support"`
// Port Range for data connections. Random if not specified
PassivePortRange PortRange `json:"passive_port_range" mapstructure:"passive_port_range"`
acmeDomain string
}
// ShouldBind returns true if there is at least a valid binding
func (c *Configuration) ShouldBind() bool {
for _, binding := range c.Bindings {
if binding.IsValid() {
return true
}
}
return false
}
func (c *Configuration) getKeyPairs(configDir string) []common.TLSKeyPair {
var keyPairs []common.TLSKeyPair
for _, binding := range c.Bindings {
certificateFile := getConfigPath(binding.CertificateFile, configDir)
certificateKeyFile := getConfigPath(binding.CertificateKeyFile, configDir)
if certificateFile != "" && certificateKeyFile != "" {
keyPairs = append(keyPairs, common.TLSKeyPair{
Cert: certificateFile,
Key: certificateKeyFile,
ID: binding.GetAddress(),
})
}
}
var certificateFile, certificateKeyFile string
if c.acmeDomain != "" {
certificateFile, certificateKeyFile = util.GetACMECertificateKeyPair(c.acmeDomain)
} else {
certificateFile = getConfigPath(c.CertificateFile, configDir)
certificateKeyFile = getConfigPath(c.CertificateKeyFile, configDir)
}
if certificateFile != "" && certificateKeyFile != "" {
keyPairs = append(keyPairs, common.TLSKeyPair{
Cert: certificateFile,
Key: certificateKeyFile,
ID: common.DefaultTLSKeyPaidID,
})
}
return keyPairs
}
func (c *Configuration) loadFromProvider() error {
configs, err := dataprovider.GetConfigs()
if err != nil {
return fmt.Errorf("unable to load config from provider: %w", err)
}
configs.SetNilsToEmpty()
if configs.ACME.Domain == "" || !configs.ACME.HasProtocol(common.ProtocolFTP) {
return nil
}
crt, key := util.GetACMECertificateKeyPair(configs.ACME.Domain)
if crt != "" && key != "" {
if _, err := os.Stat(crt); err != nil {
logger.Error(logSender, "", "unable to load acme cert file %q: %v", crt, err)
return nil
}
if _, err := os.Stat(key); err != nil {
logger.Error(logSender, "", "unable to load acme key file %q: %v", key, err)
return nil
}
c.acmeDomain = configs.ACME.Domain
logger.Info(logSender, "", "acme domain set to %q", c.acmeDomain)
return nil
}
return nil
}
// Initialize configures and starts the FTP server
func (c *Configuration) Initialize(configDir string) error {
if err := c.loadFromProvider(); err != nil {
return err
}
logger.Info(logSender, "", "initializing FTP server with config %+v", *c)
if !c.ShouldBind() {
return common.ErrNoBinding
}
keyPairs := c.getKeyPairs(configDir)
if len(keyPairs) > 0 {
mgr, err := common.NewCertManager(keyPairs, configDir, logSender)
if err != nil {
return err
}
mgr.SetCACertificates(c.CACertificates)
if err := mgr.LoadRootCAs(); err != nil {
return err
}
mgr.SetCARevocationLists(c.CARevocationLists)
if err := mgr.LoadCRLs(); err != nil {
return err
}
certMgr = mgr
}
serviceStatus = ServiceStatus{
Bindings: nil,
PassivePortRange: c.PassivePortRange,
}
exitChannel := make(chan error, 1)
for idx, binding := range c.Bindings {
if !binding.IsValid() {
continue
}
server := NewServer(c, configDir, binding, idx)
go func(s *Server) {
ftpLogger := logger.LeveledLogger{Sender: "ftpserverlib"}
ftpServer := ftpserver.NewFtpServer(s)
ftpServer.Logger = ftpLogger.With("server_id", fmt.Sprintf("FTP_%v", s.ID))
logger.Info(logSender, "", "starting FTP serving, binding: %v", s.binding.GetAddress())
util.CheckTCP4Port(s.binding.Port)
exitChannel <- ftpServer.ListenAndServe()
}(server)
serviceStatus.Bindings = append(serviceStatus.Bindings, binding)
}
serviceStatus.IsActive = true
return <-exitChannel
}
// ReloadCertificateMgr reloads the certificate manager
func ReloadCertificateMgr() error {
if certMgr != nil {
return certMgr.Reload()
}
return nil
}
// GetStatus returns the server status
func GetStatus() ServiceStatus {
return serviceStatus
}
func parsePassiveIP(passiveIP string) (string, error) {
ip := net.ParseIP(passiveIP)
if ip == nil {
return "", fmt.Errorf("the provided passive IP %q is not valid", passiveIP)
}
ip = ip.To4()
if ip == nil {
return "", fmt.Errorf("the provided passive IP %q is not a valid IPv4 address", passiveIP)
}
return ip.String(), nil
}
func getConfigPath(name, configDir string) string {
if !util.IsFileInputValid(name) {
return ""
}
if name != "" && !filepath.IsAbs(name) {
return filepath.Join(configDir, name)
}
return name
}