392 lines
14 KiB
Go
392 lines
14 KiB
Go
package main
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import (
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"encoding/json"
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"fmt"
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"log"
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"log/syslog"
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"net"
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"os"
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"os/exec"
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"os/signal"
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"path"
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"path/filepath"
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"runtime"
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"runtime/debug"
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"strings"
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"syscall"
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"time"
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"github.com/hanwen/go-fuse/fuse"
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"github.com/hanwen/go-fuse/fuse/nodefs"
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"github.com/hanwen/go-fuse/fuse/pathfs"
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"github.com/rfjakob/gocryptfs/internal/configfile"
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"github.com/rfjakob/gocryptfs/internal/contentenc"
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"github.com/rfjakob/gocryptfs/internal/cryptocore"
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"github.com/rfjakob/gocryptfs/internal/ctlsock"
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"github.com/rfjakob/gocryptfs/internal/exitcodes"
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"github.com/rfjakob/gocryptfs/internal/fusefrontend"
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"github.com/rfjakob/gocryptfs/internal/fusefrontend_reverse"
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"github.com/rfjakob/gocryptfs/internal/nametransform"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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// doMount mounts an encrypted directory.
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// Called from main.
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func doMount(args *argContainer) {
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// Check mountpoint
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var err error
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args.mountpoint, err = filepath.Abs(flagSet.Arg(1))
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if err != nil {
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tlog.Fatal.Printf("Invalid mountpoint: %v", err)
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os.Exit(exitcodes.MountPoint)
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}
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// We cannot mount "/home/user/.cipher" at "/home/user" because the mount
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// will hide ".cipher" also for us.
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if args.cipherdir == args.mountpoint || strings.HasPrefix(args.cipherdir, args.mountpoint+"/") {
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tlog.Fatal.Printf("Mountpoint %q would shadow cipherdir %q, this is not supported",
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args.mountpoint, args.cipherdir)
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os.Exit(exitcodes.MountPoint)
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}
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// Reverse-mounting "/foo" at "/foo/mnt" means we would be recursively
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// encrypting ourselves.
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if strings.HasPrefix(args.mountpoint, args.cipherdir+"/") {
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tlog.Fatal.Printf("Mountpoint %q is contained in cipherdir %q, this is not supported",
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args.mountpoint, args.cipherdir)
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os.Exit(exitcodes.MountPoint)
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}
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if args.nonempty {
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err = isDir(args.mountpoint)
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} else {
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err = isDirEmpty(args.mountpoint)
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// OSXFuse will create the mountpoint for us ( https://github.com/rfjakob/gocryptfs/issues/194 )
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if runtime.GOOS == "darwin" && os.IsNotExist(err) {
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tlog.Info.Printf("Mountpoint %q does not exist, but should be created by OSXFuse",
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args.mountpoint)
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err = nil
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}
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}
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if err != nil {
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tlog.Fatal.Printf("Invalid mountpoint: %v", err)
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os.Exit(exitcodes.MountPoint)
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}
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// Open control socket early so we can error out before asking the user
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// for the password
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if args.ctlsock != "" {
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// We must use an absolute path because we cd to / when daemonizing.
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// This messes up the delete-on-close logic in the unix socket object.
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args.ctlsock, _ = filepath.Abs(args.ctlsock)
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var sock net.Listener
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sock, err = net.Listen("unix", args.ctlsock)
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if err != nil {
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tlog.Fatal.Printf("ctlsock: %v", err)
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os.Exit(exitcodes.CtlSock)
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}
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args._ctlsockFd = sock
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// Close also deletes the socket file
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defer func() {
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err = sock.Close()
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if err != nil {
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tlog.Warn.Printf("ctlsock close: %v", err)
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}
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}()
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}
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// We cannot use JSON for pretty-printing as the fields are unexported
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tlog.Debug.Printf("cli args: %#v", args)
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// Initialize gocryptfs
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fs, wipeKeys := initFuseFrontend(args)
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// Initialize go-fuse FUSE server
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srv := initGoFuse(fs, args)
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// Try to wipe secrect keys from memory after unmount
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defer wipeKeys()
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tlog.Info.Println(tlog.ColorGreen + "Filesystem mounted and ready." + tlog.ColorReset)
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// We have been forked into the background, as evidenced by the set
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// "notifypid".
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if args.notifypid > 0 {
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// Chdir to the root directory so we don't block unmounting the CWD
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os.Chdir("/")
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// Switch to syslog
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if !args.nosyslog {
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// Switch all of our logs and the generic logger to syslog
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tlog.Info.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_INFO)
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tlog.Debug.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_DEBUG)
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tlog.Warn.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
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tlog.SwitchLoggerToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
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// Daemons should redirect stdin, stdout and stderr
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redirectStdFds()
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}
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// Disconnect from the controlling terminal by creating a new session.
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// This prevents us from getting SIGINT when the user presses Ctrl-C
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// to exit a running script that has called gocryptfs.
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_, err = syscall.Setsid()
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if err != nil {
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tlog.Warn.Printf("Setsid: %v", err)
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}
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// Send SIGUSR1 to our parent
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sendUsr1(args.notifypid)
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}
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// Increase the open file limit to 4096. This is not essential, so do it after
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// we have switched to syslog and don't bother the user with warnings.
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setOpenFileLimit()
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// Wait for SIGINT in the background and unmount ourselves if we get it.
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// This prevents a dangling "Transport endpoint is not connected"
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// mountpoint if the user hits CTRL-C.
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handleSigint(srv, args.mountpoint)
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// Return memory that was allocated for scrypt (64M by default!) and other
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// stuff that is no longer needed to the OS
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debug.FreeOSMemory()
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// Jump into server loop. Returns when it gets an umount request from the kernel.
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srv.Serve()
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}
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// setOpenFileLimit tries to increase the open file limit to 4096 (the default hard
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// limit on Linux).
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func setOpenFileLimit() {
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var lim syscall.Rlimit
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err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim)
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if err != nil {
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tlog.Warn.Printf("Getting RLIMIT_NOFILE failed: %v", err)
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return
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}
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if lim.Cur >= 4096 {
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return
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}
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lim.Cur = 4096
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err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &lim)
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if err != nil {
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tlog.Warn.Printf("Setting RLIMIT_NOFILE to %+v failed: %v", lim, err)
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// %+v output: "{Cur:4097 Max:4096}" ^
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}
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}
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// ctlsockFs satisfies both the pathfs.FileSystem and the ctlsock.Interface
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// interfaces
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type ctlsockFs interface {
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pathfs.FileSystem
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ctlsock.Interface
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}
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// initFuseFrontend - initialize gocryptfs/fusefrontend
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// Calls os.Exit on errors
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func initFuseFrontend(args *argContainer) (pfs pathfs.FileSystem, wipeKeys func()) {
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// Get master key (may prompt for the password) and read config file
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masterkey, confFile := getMasterKey(args)
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// Reconciliate CLI and config file arguments into a fusefrontend.Args struct
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// that is passed to the filesystem implementation
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cryptoBackend := cryptocore.BackendGoGCM
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if args.openssl {
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cryptoBackend = cryptocore.BackendOpenSSL
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}
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if args.aessiv {
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cryptoBackend = cryptocore.BackendAESSIV
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}
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// forceOwner implies allow_other, as documented.
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// Set this early, so args.allow_other can be relied on below this point.
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if args._forceOwner != nil {
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args.allow_other = true
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}
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frontendArgs := fusefrontend.Args{
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Cipherdir: args.cipherdir,
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PlaintextNames: args.plaintextnames,
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LongNames: args.longnames,
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ConfigCustom: args._configCustom,
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NoPrealloc: args.noprealloc,
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SerializeReads: args.serialize_reads,
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ForceDecode: args.forcedecode,
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ForceOwner: args._forceOwner,
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Exclude: args.exclude,
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}
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// confFile is nil when "-zerokey" or "-masterkey" was used
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if confFile != nil {
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// Settings from the config file override command line args
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frontendArgs.PlaintextNames = confFile.IsFeatureFlagSet(configfile.FlagPlaintextNames)
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args.raw64 = confFile.IsFeatureFlagSet(configfile.FlagRaw64)
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args.hkdf = confFile.IsFeatureFlagSet(configfile.FlagHKDF)
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if confFile.IsFeatureFlagSet(configfile.FlagAESSIV) {
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cryptoBackend = cryptocore.BackendAESSIV
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} else if args.reverse {
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tlog.Fatal.Printf("AES-SIV is required by reverse mode, but not enabled in the config file")
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os.Exit(exitcodes.Usage)
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}
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}
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// If allow_other is set and we run as root, try to give newly created files to
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// the right user.
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if args.allow_other && os.Getuid() == 0 {
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frontendArgs.PreserveOwner = true
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}
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jsonBytes, _ := json.MarshalIndent(frontendArgs, "", "\t")
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tlog.Debug.Printf("frontendArgs: %s", string(jsonBytes))
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// Init crypto backend
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cCore := cryptocore.New(masterkey, cryptoBackend, contentenc.DefaultIVBits, args.hkdf, args.forcedecode)
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cEnc := contentenc.New(cCore, contentenc.DefaultBS, args.forcedecode)
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nameTransform := nametransform.New(cCore.EMECipher, frontendArgs.LongNames, args.raw64)
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// After the crypto backend is initialized,
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// we can purge the master key from memory.
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for i := range masterkey {
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masterkey[i] = 0
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}
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masterkey = nil
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// Spawn fusefrontend
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var fs ctlsockFs
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if args.reverse {
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if cryptoBackend != cryptocore.BackendAESSIV {
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log.Panic("reverse mode must use AES-SIV, everything else is insecure")
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}
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fs = fusefrontend_reverse.NewFS(frontendArgs, cEnc, nameTransform)
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} else {
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fs = fusefrontend.NewFS(frontendArgs, cEnc, nameTransform)
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}
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// We have opened the socket early so that we cannot fail here after
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// asking the user for the password
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if args._ctlsockFd != nil {
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go ctlsock.Serve(args._ctlsockFd, fs)
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}
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return fs, func() { cCore.Wipe() }
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}
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func initGoFuse(fs pathfs.FileSystem, args *argContainer) *fuse.Server {
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// pathFsOpts are passed into go-fuse/pathfs
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pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
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if args.sharedstorage {
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// shared storage mode disables hard link tracking as the backing inode
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// numbers may change behind our back:
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// https://github.com/rfjakob/gocryptfs/issues/156
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pathFsOpts.ClientInodes = false
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}
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if args.reverse {
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// Reverse mode is read-only, so we don't need a working link().
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// Disable hard link tracking to avoid strange breakage on duplicate
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// inode numbers ( https://github.com/rfjakob/gocryptfs/issues/149 ).
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pathFsOpts.ClientInodes = false
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}
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pathFs := pathfs.NewPathNodeFs(fs, pathFsOpts)
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var fuseOpts *nodefs.Options
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if args.sharedstorage {
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// sharedstorage mode sets all cache timeouts to zero so changes to the
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// backing shared storage show up immediately.
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fuseOpts = &nodefs.Options{}
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} else {
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fuseOpts = &nodefs.Options{
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// These options are to be compatible with libfuse defaults,
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// making benchmarking easier.
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NegativeTimeout: time.Second,
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AttrTimeout: time.Second,
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EntryTimeout: time.Second,
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}
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}
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conn := nodefs.NewFileSystemConnector(pathFs.Root(), fuseOpts)
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mOpts := fuse.MountOptions{
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// Writes and reads are usually capped at 128kiB on Linux through
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// the FUSE_MAX_PAGES_PER_REQ kernel constant in fuse_i.h. Our
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// sync.Pool buffer pools are sized acc. to the default. Users may set
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// the kernel constant higher, and Synology NAS kernels are known to
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// have it >128kiB. We cannot handle more than 128kiB, so we tell
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// the kernel to limit the size explicitly.
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MaxWrite: fuse.MAX_KERNEL_WRITE,
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Options: []string{fmt.Sprintf("max_read=%d", fuse.MAX_KERNEL_WRITE)},
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}
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if args.allow_other {
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tlog.Info.Printf(tlog.ColorYellow + "The option \"-allow_other\" is set. Make sure the file " +
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"permissions protect your data from unwanted access." + tlog.ColorReset)
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mOpts.AllowOther = true
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// Make the kernel check the file permissions for us
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mOpts.Options = append(mOpts.Options, "default_permissions")
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}
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if args.forcedecode {
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tlog.Info.Printf(tlog.ColorYellow + "THE OPTION \"-forcedecode\" IS ACTIVE. GOCRYPTFS WILL RETURN CORRUPT DATA!" +
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tlog.ColorReset)
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}
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if args.nonempty {
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mOpts.Options = append(mOpts.Options, "nonempty")
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}
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// Set values shown in "df -T" and friends
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// First column, "Filesystem"
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fsname := args.cipherdir
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if args.fsname != "" {
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fsname = args.fsname
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}
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mOpts.Options = append(mOpts.Options, "fsname="+fsname)
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// Second column, "Type", will be shown as "fuse." + Name
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mOpts.Name = "gocryptfs"
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if args.reverse {
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mOpts.Name += "-reverse"
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}
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// Add a volume name if running osxfuse. Otherwise the Finder will show it as
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// something like "osxfuse Volume 0 (gocryptfs)".
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if runtime.GOOS == "darwin" {
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mOpts.Options = append(mOpts.Options, "volname="+path.Base(args.mountpoint))
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}
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// The kernel enforces read-only operation, we just have to pass "ro".
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// Reverse mounts are always read-only.
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if args.ro || args.reverse {
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mOpts.Options = append(mOpts.Options, "ro")
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} else if args.rw {
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mOpts.Options = append(mOpts.Options, "rw")
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}
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// If both "nosuid" and "suid" were passed, the safer option wins.
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if args.nosuid {
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mOpts.Options = append(mOpts.Options, "nosuid")
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} else if args.suid {
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mOpts.Options = append(mOpts.Options, "suid")
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}
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if args.nodev {
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mOpts.Options = append(mOpts.Options, "nodev")
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} else if args.dev {
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mOpts.Options = append(mOpts.Options, "dev")
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}
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if args.noexec {
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mOpts.Options = append(mOpts.Options, "noexec")
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} else if args.exec {
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mOpts.Options = append(mOpts.Options, "exec")
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}
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// Add additional mount options (if any) after the stock ones, so the user has
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// a chance to override them.
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if args.ko != "" {
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parts := strings.Split(args.ko, ",")
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tlog.Debug.Printf("Adding -ko mount options: %v", parts)
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mOpts.Options = append(mOpts.Options, parts...)
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}
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srv, err := fuse.NewServer(conn.RawFS(), args.mountpoint, &mOpts)
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if err != nil {
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tlog.Fatal.Printf("fuse.NewServer failed: %s", strings.TrimSpace(err.Error()))
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if runtime.GOOS == "darwin" {
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tlog.Info.Printf("Maybe you should run: /Library/Filesystems/osxfuse.fs/Contents/Resources/load_osxfuse")
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}
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os.Exit(exitcodes.FuseNewServer)
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}
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srv.SetDebug(args.fusedebug)
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// All FUSE file and directory create calls carry explicit permission
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// information. We need an unrestricted umask to create the files and
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// directories with the requested permissions.
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syscall.Umask(0000)
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return srv
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}
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func handleSigint(srv *fuse.Server, mountpoint string) {
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ch := make(chan os.Signal, 1)
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signal.Notify(ch, os.Interrupt)
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signal.Notify(ch, syscall.SIGTERM)
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go func() {
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<-ch
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err := srv.Unmount()
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if err != nil {
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tlog.Warn.Printf("handleSigint: srv.Unmount returned %v", err)
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if runtime.GOOS == "linux" {
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// MacOSX does not support lazy unmount
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tlog.Info.Printf("Trying lazy unmount")
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cmd := exec.Command("fusermount", "-u", "-z", mountpoint)
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cmd.Stdout = os.Stdout
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cmd.Stderr = os.Stderr
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cmd.Run()
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}
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}
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os.Exit(exitcodes.SigInt)
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}()
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}
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